Growing Risk
Addressing the Invasive
Potential of Bioenergy Feedstocks
Aviva Glaser
and
Patty Glick
2012
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
1
Growing Risk
Addressing the Invasive
Potential of Bioenergy
Feedstocks
Prepared by
Aviva Glaser, Legislative Representative, Agriculture Policy
Patty Glick, Senior Climate Change Specialist
Acknowledgements
This report was made possible due to the generous support of the Doris Duke Charitable Foundation.
The authors wish to thank many people for their time and contributions to this report. We would like
to thank the following National Wildlife Federation staff for providing valuable edits and feedback: Julie
Sibbing, Bruce Stein, Doug Inkley, and Lara Bryant. Additionally, we would like to thank several experts
for their time, input, and helpful review comments: Dr. Joseph DiTomaso, University of California,
Davis; Dr. Doria Gordon, The Nature Conservancy; Bryan Endres, J.D., University of Illinois; Dr. Lauren
Quinn, University of Illinois; Doug Johnson, California Invasive Plant Council; and Read Porter, J.D.,
Environmental Law Institute.
Designed by
Maja Smith, MajaDesign, Inc.
© 2012 National Wildlife Federation
Cover image: The highly-invasive giant reed (Arundo donax), a candidate species for bioenergy
production, has taken over vast areas along the Rio Grande, as seen in this aerial view near Eagle Pass,
Texas. Credit: John Goolsby, USDA.
Suggested citation: Glaser, A. and P. Glick. 2012. Growing Risk: Addressing the Invasive
Potential of Bioenergy Feedstocks. Washington, DC: National Wildlife Federation.
i
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Table of
Contents
Little bluestem, a native grass. Credit: NRCS.
1. Executive Summary
1
2. Overview 3
The Promise of Bioenergy 3
Risks from Bioenergy 4
A Focus on Invasiveness 4
3. Invasive Bioenergy Feedstocks: A Major Concern 7
7
Weediness: A Characteristic of a “Good” Biomass Plant 8
Harvesting Existing Invasive Plants: Win-Win or Pandora’s Box?
9
Adding Climate Change to the Mix10
Selective Breeding and Genetic Modification 11
The Myth of Total Sterility12
Invasive Plans Can Wreak Havoc on Ecosystems and Society
4. Case Studies of Feedstocks of Concern 14
Giant Reed (Arundo donax) 14
Miscanthus (Miscanthus species) 16
18
Reed Canarygrass (Phalaris arundinacea) 20
Algae 22
Napiergrass (Pennisetum purpureum) 24
Genetically Modified Eucalyptus (Eucalyptus grandis x Eucalyptus urophylla) 5. Minimizing the Risks: The Importance of Embracing Precaution 26
Current Regulation of Invasive Species26
Screening Tools 32
6. Conclusions and Recommendations
34
Concluding Thoughts 41
7. Endnotes 42
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
ii
1
Executive
Summary
W
ithout question, America needs to
transition to a cleaner, more sustainable
energy future. As we move forward with
our energy choices, we must be mindful of how shortterm economic decisions can come with unintended
consequences and high long-term costs to society and
the environment. Bioenergy is one homegrown source
of renewable energy that could help meet some of our
energy needs. However, in order to create a truly
clean energy future, bioenergy must be produced in a
way that has long-term economic viability, helps address
climate change, and protects and enhances native
habitats and ecosystems.
Parabel grows non-genetically modified, native aquatic
plants in Florida to use as a renewable energy feedstock.
Credit: Julie Sibbing.
In order to create a truly clean energy
future, bioenergy must be produced in a
way that has long-term economic viability,
helps address climate change, and
protects and enhances native habitats
and ecosystems.
4
The explosion in federal and state mandates and
incentives for renewable energy in recent years has
led to a greatly increased demand for cheap and
plentiful biomass from a variety of plants and microorganisms. This increased demand for bioenergy has
led to considerable interest in a number of non-native
and potentially invasive species that are currently being
cultivated or considered for use as bioenergy crops. In
fact, some of the very characteristics that make a plant
particularly useful as a source of biomass energy (e.g.,
rapid growth, competitiveness, tolerance of a range of
climate conditions) are the same characteristics that
make a plant a potentially highly invasive species.
Widespread cultivation of exotic and genetically modified
species for bioenergy is becoming increasingly likely.
Should these species escape cultivated areas and enter
nearby habitats, the results could be devastating for
native ecosystems as well as the economy. Very little is
known about the full potential scope of the problem, yet
the industry is moving full speed ahead. Already, there
are examples of intentional cultivation of biomass species
that are known to be invasive or have the potential to
become invasive. For instance:
• Giant reed (Arundo donax) is being used as a bioenergy
crop in Florida, despite the fact that it has been known
to invade important riparian ecosystems and displace
habitat for native species in states across the southern
half of the country.
• Reed canarygrass (Phalaris arundinacea), which is
considered to be one of the most harmful invasive species
in America’s wetlands, rivers, and lakes, is being proposed
for cultivation as a bioenergy feedstock in several areas,
including the Eastern Upper Peninsula of Michigan.
As a result, invasive species that we may have been able
to inhibit are causing widespread environmental and
economic harm.
We now have an opportunity to prevent irreparable harm
by heeding sensible precautions. With foresight and careful
screening, we have important opportunities to minimize
and, where possible, prevent negative impacts of biomass
feedstocks on the nation’s communities and ecosystems.
We recommend some key actions to help ensure that the
next generation of bioenergy does not fuel the next invasive
species problem.
• Cylindro (Cylindrospermopsis raciborskii), a type of
algae that is associated with toxic algal blooms in the Great
Lakes region, is just one of many non-native or modified
strains of algae under consideration for bioenergy, even
though the fast growth rate of algae and the inherent
difficulty in containing them is a major concern.
1. Future bioenergy development should encourage
ecological restoration and improve wildlife habitat through
the use of ecologically beneficial biomass feedstocks such
as waste materials and sustainably collected native plants
and forest residues.
• Napiergrass (Pennisetum purpureum), also called
2. Federal and state governments should conduct
coordinated efforts to restrict or prohibit the use of
known invasive species as dedicated bioenergy
feedstocks through rigorous Weed Risk Assessment
(WRA) screening protocols.
elephant grass, has been listed as an invasive plant
in Florida and described as one of the most problematic
weeds in the world, and yet BP is currently developing
a cultivated variety of it as an energy crop in the Gulf
Coast Region.
In addition, the use of already highly-destructive invasive
plants for bioenergy, including Chinese tallow (Triadica
sebifera), kudzu (Pueraria montana var. lobata), Eurasian
watermilfoil (Myriophyllum spicatum), and common reed
(Phragmites australis), is being proposed as a way to
capitalize on the potential benefits of the plants while
providing an opportunity for their control. While this
may allow for a win-win for ecosystem restoration and
renewable energy production, it also raises the concern
that the active re-establishment of the invasive species,
rather than their control, might be incentivized.
The severity of this threat is by no means trivial. Every
year, invasive species cost the United States billions of
dollars and affect countless acres of native ecosystems.
Researchers estimate that nearly half of the species listed
as threatened or endangered under the U.S. Endangered
Species Act are at risk, at least in part, due to the impacts
of invasive species. Despite this, few safeguards exist
in law and in practice to prevent the spread of invasive
species. To date, current laws and regulations dealing
with invasive species have been reactive and piecemeal.
3. State and federal governments should implement
rigorous monitoring, early detection, and rapid response
protocols, paid for by feedstock producers through
insurance bonding or other financial mechanisms.
4. Feedstock producers should adopt best management
plans for monitoring and mitigation to reduce the risk
of invasion.
5. The federal government should assign liability to
feedstock producers for damages from and remediation of
invasions by feedstock varieties that they develop.
6. Governments and businesses should better account
for the economic risks associated with invasiveness of
feedstocks when assessing relevant costs and benefits of
potential bioenergy projects.
Bioenergy can be an important part of a sustainable energy
future, but only if it is produced in a way that safeguards
native ecosystems and minimizes the risk of invasion.
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
2
2
Overview
A
s the world focuses greater attention on
finding alternatives to fossil fuels in order to
meet our growing energy demands, reduce
carbon emissions, and enhance global security,
interest in expanding the use of bioenergy has grown
considerably. Bioenergy – also called biomass energy –
refers to the energy resources derived from plants and
animals or their metabolic products. Sources of biomass
can include trees, annual and perennial crop plants,
algae, and other plants, as well as some organic waste
materials and byproducts from other manufacturing
processes (See Box 1, page 5). When these feedstocks
are used to produce energy in the form of liquid fuels,
such as ethanol and biodiesel, they are referred to as
biofuels. Biomass can also be used to produce energy
in the form of heat and electricity generation. Indeed, the
use of wood for cooking and heating has long been a
part of human history.
The Promise of Bioenergy
Native perennial grasses have great potential as energy crops.
Credit: ©iStockphoto.com/Prairie Art Project.
One of the attractions of bioenergy is
that unlike fossil fuels, which have a finite
global supply, bioenergy can be grown
and used repeatedly – and thus can be
considered a form of renewable energy.
3
One of the attractions of bioenergy is that unlike fossil
fuels, which have a finite global supply, bioenergy can
be grown and used repeatedly – and thus can be
considered a form of renewable energy. Renewable
energy (including wind, solar, geothermal, and biomass
energy) is becoming an increasingly important part
of America’s energy portfolio. According to the U.S.
Energy Information Administration, renewable energy’s
market share reached 8 percent of total U.S. energy
consumption in 2009.1 In addition, many states have
enacted minimum renewable energy requirements for
both transportation and electricity generation. Currently,
biomass is the largest contributor to renewable energy in
the United States and around the world, and accounts
for about 11 percent of total primary energy consumed.2
Research suggests that increased production of energy
from biomass resources may have the potential to
considerably offset the use of fossil fuels.3,4
Credit: DOE Office of Biological and Environmental Research.
In addition, the production and use of bioenergy is being
widely touted as a way to help mitigate climate change.5,6
Ideally, biomass fuel production and use would be at
least “carbon neutral.” In other words, feedstocks absorb
carbon dioxide (CO2) as they grow, and the carbon is
released back into the atmosphere when the plants
are harvested and used for energy, with no net gain in
atmospheric carbon. In principle, feedstocks have the
potential to even be “carbon negative” if more carbon is
taken up than is released, as root stocks develop and store
carbon. Ultimately, net increases in atmospheric CO2 would
slow if truly carbon neutral bioenergy resources displaced
the use of fossil fuels, which increase atmospheric carbon
by transferring carbon from subterranean reserves into
the atmosphere when combusted. However, it is critical
to acknowledge that the greenhouse gas implications of
bioenergy are complex, and that climate-related benefits
cannot automatically be assumed.7,8,9
Risks from Bioenergy
As with all energy resources, it is important to recognize
that development and use of bioenergy has both benefits
and costs, and there is potential for considerable societal,
economic, and environmental tradeoffs. There are a
number of environmental concerns associated with the
use of bioenergy, including the loss or degradation of
native ecosystems, declining soil and water quality, and
the invasive potential of the feedstocks themselves.10,11
One of the key issues related to bioenergy is land use.
As demand for bioenergy grows, so will the areas of
land needed for growing biomass feedstocks. The
implications of this for other current and potential uses of
land to meet competing needs, such as food production,
are significant.12 Of particular concern for biodiversity
conservation is the potential for natural areas such
as forests or grasslands to be converted to cultivated
bioenergy cropping systems or monocultures.
Furthermore, as mentioned above, research has found
that not all bioenergy is actually carbon neutral, and,
depending on a number of factors, some forms of
bioenergy may in fact lead to increased emissions of
CO213,14 For example, it can take more than 50
years for trees to regrow and recapture the total
carbon released when mature trees are used for
bioenergy. While bioenergy holds great promise for
meeting some of renewable energy needs, the impact
of unsustainable bioenergy development could be
devastating to natural resources.
A Focus on Invasiveness
While all of the concerns associated with the expansion
of bioenergy require careful consideration, this report
focuses on only one of these concerns – the potential
invasiveness of bioenergy feedstocks – an issue
that has only recently begun garnering significant
attention.25 Numerous studies have shown that some
of the plants considered most promising in terms of
bioenergy capacity may actually be extremely invasive
and potentially quite harmful to native species in areas
where they have been introduced.26,37,28,29 History has
repeatedly shown that introductions of invasive species,
even when well-intentioned, can lead to widespread
unintended environmental and economic consequences.
As Raghu et al. (2011) aptly state, “[t]he road to species
introductions is often paved with good intentions, but is
littered with their consequent legacy.”30
Invasive species (including plants, animals, and other
organisms) are one of the primary threats to North
America’s native species and ecosystems. An invasive
species is defined by the federal government as “an alien
species whose introduction does or is likely to cause
economic or environmental harm or harm to human
health.”31 While only a small percentage of the estimated
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
4
Box 1. The Importance of Fostering a New Generation of Bioenergy Feedstocks:
Moving Beyond Corn-based Ethanol
I
n the early stages of bioenergy development,
the primary feedstocks in the United States
have included corn, sugar cane, and other
annual food and feed crops for ethanol, wood for heat
and electricity, and to a lesser extent, palm, sunflower,
and rapeseed for biodiesel and other oils. Corn, in
particular, has been the predominant bioenergy crop.
In 2010, the United States produced 13.2 billion
gallons of corn-based ethanol, making it the
world’s top producer of the fuel at 57.5 percent of
global production.15
Production and use of bioenergy in America is
expected to continue to grow considerably over the
next decade. Under the 2007 Energy Independence
and Security Act, the nation has set a Renewable Fuel
Standard (RFS) to significantly increase the proportion
of bio-based fuels for transportation, from current
production levels of over 13 billion gallons a year to 36
billion gallons by 2022. This would account for about
7 percent of the expected annual gasoline and diesel
consumption above a business-as-usual scenario.16
Corn has been the predominant bioenergy crop in the U.S.
Credit: Fishhawk on flickr.
Under the law, the total use of ethanol from corn is
bird species.22 In addition, there are concerns that
capped at no higher than 15 billion gallons. Over
the expansion of corn production for bioenergy could
the last few years, some troubling ecological and
further exacerbate water quality problems in some
economic issues have arisen regarding the use
areas due to expansion in the use of agricultural
of corn as a bioenergy feedstock. For example, a
chemicals and nutrients such as nitrogen and
number of studies have found that the cultivation
phosphorous.23,24
and production of corn-based ethanol typically
consumes more energy than it ultimately generates,
While the nation’s demand for corn-based ethanol
given the relatively large amount of fertilizers,
will likely continue to grow in the near-term until
pesticides, and other energy-intensive inputs and
it reaches its cap, there has been strong interest
17,18,19,20,21
activities required.
Researchers have also
and effort to identify new “advanced” or “second
found that expansion of corn production has led to
generation” bioenergy feedstocks that can optimize
reduced populations of already declining grassland
energy outputs with fewer economic or environmental
(continued)
5
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
inputs. Particular emphasis is being placed on
cellulosic (defined as renewable fuel derived from plants
cellulosic bioenergy, which is produced from fibrous
that achieves a 60 percent reduction in greenhouse
plant material from such things as perennial grasses
gas emissions compared to gasoline) and advanced
[such as reed canarygrass (Phalaris arundinacea),
bioenergy (renewable fuel derived from biomass other
switchgrass (Panicum virgatum), miscanthus
than corn starch that achieves a 50 percent greenhouse
(Miscanthus spp.), and giant reed (Arundo donax)]
gas reduction requirement). As this report highlights,
and fast-growing trees [such as poplar (Populus spp.),
however, these next generation feedstocks are not
willows (Salix spp.) and eucalyptus (Eucalyptus spp.)].
necessarily more benign than their predecessors. While
Research is also being conducted on the potential for
they may be potentially more productive and efficient
so-called “third-generation” bioenergy resources from
than first generation feedstocks, next generation
algae and other “micro crops”. Ultimately, more than
feedstocks also pose a greater risk of becoming invasive.
half of the total volume of the RFS must come from
50,000 non-native (exotic, alien) species in the United
States are invasive, those that are can cause tremendous
ecological problems and often lead to considerable
economic impacts.32,33,34
damage by invasive species in the United States is at
least $120 billion annually.40 The annual cost associated
with plants alone is estimated at $34.5 billion.41
This report:
Once introduced into a new environment, invasive
plants can out-compete native species for limited
resources such as space to grow, light, nutrients and
water.35 Invasive animals (including insects) can harm
native forage or prey species, as well as compete with
native animals for forage and prey. Invasive diseases of
plants and animals can spread rapidly in native species
that have little or no resistance. Invasive species can
have a significant impact on ecosystems as well as
human societies by disrupting food webs, decreasing
biodiversity, altering important ecosystem functions such
as fire ecology, damaging agriculture and infrastructure,
and harming human health.36 In addition, researchers
estimate that nearly half of the species that are listed as
threatened or endangered under the U.S. Endangered
Species Act are at risk due, at least in part, to the
impacts of invasive species (including plants, animals,
and microorganisms).37,38
• Reviews the current state of knowledge on the
•
•
•
•
invasive potential of plants being considered
for use for bioenergy,
Profiles six of these potentially invasive
feedstocks,
Discusses methodologies for screening feedstocks
and mitigating potentially invasive properties,
Provides an overview of the legal and policy
framework within the United States that could
minimize or mitigate this risk, and
Offers a series of policy recommendations.
Efforts to control invasive species, combined with
economic losses due to the degradation or destruction of
critical ecosystem functions, can cost billions of dollars a
year in the United States.39 In fact, analysis suggests that
the economic damage associated with control of and
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
6
3
Invasive Bioenergy
Feedstocks: A
Major Concern
Invasive Plants Can Wreak Havoc
on Ecosystems and Society
Exactly how many invasive plants species currently exist
in the United States is unknown. However, we do know
that some of the most harmful plants were brought in
intentionally for horticultural, agricultural, and forestry
purposes.42,43,44,45 For example, three species originally
introduced for landscaping and erosion control purposes,
including purple loosestrife (Lythrum salicaria), kudzu
(Pueraria montana var. lobata), and saltcedar (Tamarix
spp.), have turned out to be among the most highly
invasive and damaging species in the country.46,47
Highly-invasive kudzu covering everything in its path.
Credit: James H. Miller, USDA Forest Service, Bugwood.org.
All too often, the extent of the
problems created by an invasive
species is not fully recognized until
a landscape or ecosystem has been
dramatically modified.
7
Other problematic species were purposefully introduced
for use as livestock forage [e.g., johnsongrass
(Sorghum halepense)] or were released by accident via
contaminated crop seed or other commodity imports
[e.g., cheatgrass (Bromus tectorum) and cogongrass
(Imperata cylindrica)].48 Even species that are native to
some parts of the country have proven to be harmful
invasives when introduced elsewhere. One notable
example is smooth cordgrass (Spartina alterniflora).
Smooth cordgrass is the predominant emergent salt
marsh species throughout much of the Atlantic and
Gulf coasts, where it plays an important role in the
coastal ecosystem. Given its ability to control erosion,
the species was introduced to parts of the Pacific
Coast, where it has out-competed native marsh plants
and significantly altered critical mudflats and other
coastal habitats.49
Very little attention has been given to the potential
for non-native bioenergy feedstocks to host harmful
diseases. The very real risk of disease in introduced
plants is demonstrated by the fact that kudzu is a host
species for Asian soybean rust (Phakopsora pachyrhizi),
which was first reported in the continental United States
in 2004. It is a serious disease that can cause significant
damage to soybean crops.50 Similarly, members of the
myrtle family (Myrtaceae), including eucalyptus trees,
which are potential bioenergy feedstocks, have been
found to host Puccinia psidii, a rust fungus that has
severely damaged an endangered native myrtle species
in Hawaii.51
All too often, the extent of the problems created by an
invasive species is not fully recognized until a landscape
or ecosystem has been dramatically modified.52 Studies
have found that there is often a time lag of several
decades or more between the time that a non-native
species has been introduced and when we realize it
has become a harmful invasive. By the time an invasive
species has become established, they are exceedingly
difficult to control, let alone eradicate.53 In fact, evidence
indicates that in most cases, species invasions are
essentially irreversible.54
Weediness: A Characteristic of a
“Good” Biomass Plant
Ultimately, the goal of bioenergy production is to create
the greatest amount of energy possible while minimizing
inputs such as fertilizer, agricultural chemicals, water,
and planting and tillage operations. Thus, the optimal
feedstock to maximize bioenergy production would
be one that is fast-growing, highly productive, highly
competitive, self-propagating or able to regrow rapidly,
resistant to pest and insect outbreaks, and able to
thrive in marginal environmental conditions – including
poor soil and drought. Unfortunately, many invasive
species, by their very nature, exhibit these qualities as
well (See Table 1).55 Accordingly, plants considered to
be good bioenergy candidates are often more likely
to become invasive; researchers found that in Hawaii,
for instance, approximately 70 percent of the plants
proposed for use as biofuel feedstocks had a high risk
of becoming invasive.56
In fact, evidence indicates that in
most cases, species invasions are
essentially irreversible.
Indeed, several exotic grass species that are currently
under consideration for use as bioenergy feedstocks,
including giant reed, reed canarygrass (Phalaris
arundinacea), and miscanthus (Miscanthus spp.),
are already considered invasive in some areas of the
United States.57 In California alone, more than $70
million dollars has been spent over the past 15 years to
control giant reed, which has caused extensive damage
to ecosystems and human infrastructure in many of
the state’s coastal and inland watersheds.58 Reed
canarygrass has displaced native species on thousands
Table 1. Characteristics of Ideal Biomass Crops vs. Invasive Weeds61
Characteristic of an
Ideal Biomass Crop
Characteristic Known to
Contribute to Invasiveness
Rapid growth rate
x
x
Resistent to pests and diseases
x
x
High water use efficiency
x
x
C4 photosynthesis*
x
x
Perennial
x
High yields
x
Sterility
x
Ability to grow in a wide range of climates and habitats
x
x
Rapid regrowth or self-propagation
x
x
x
* Plants with the C4 photosynthetic pathway use water more efficiently under arid conditions than plants with C3 photosynthesis.62
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
8
of acres of wetlands in southern Wisconsin.59 In addition,
some native species under consideration as bioenergy
feedstocks have the potential to become invasive if
introduced outside their native range.60
Harvesting Existing Invasive
Plants: Win-Win or Pandora’s Box?
Several studies suggest that some highly-problematic
invasive plant species could be used for biomass,
creating an economic incentive for controlling the
species. For example, Sage et al. (2009) estimate that
the amount of standing biomass of kudzu in naturally
infested areas of Maryland, Alabama, and Georgia is
high enough to significantly supplement existing biofuel
feedstocks, assuming economical harvesting and
processing techniques could be developed.63 Given its
invasive growth habit, the authors suggest that there
would be little in the way of input costs for fertilizers,
pesticides, planting, and stand management. Benefits
may also accrue by offsetting some of the estimated
$500 million per year cost to the nation from lost crop
and forest productivity, expenditures for control, and
property damage.
Water hyacinth, seen in this picture invading a stream, has been
suggested as a potential bioenergy feedstock. Credit: Kim Starr.
Two other species, Chinese tallow (Triadica sebifera or
Sapium sebiferum)64 and saltcedar,65 which are both
listed by The Nature Conservancy as among the nation’s
“Dirty Dozen” least wanted intruders, have also been
suggested as potential feedstocks for bioenergy.66
9
Chinese tallow, for example, has become widely
established across much of the South, and is known for
its prolific production of oil seeds. One study suggests
that conversion to commercial use of 500,000 acres of
non-crop upland areas in southwestern Louisiana that
currently host dense stands of tallow trees has potential
to produce 80-140 million barrels of biodiesel within a
decade.67 In addition, there is interest in using some
of the world’s most damaging aquatic invasive plants,
including water hyacinth (Eichhornia crassipes), hydrilla
(Hydrilla verticillata), Eurasian watermilfoil (Myriophyllum
spicatum) and common reed (Phragmites australis),
for bioenergy due to the desire for resource managers
to control overgrowth, as well as the fact that these
plants have significantly higher productivity rates than
many terrestrial bioenergy feedstock candidates.68,69
Researchers are also looking into the potential for using
several invasive algae species, including Gracilaria
salicornia, which is prevalent in coastal waters
throughout the Hawaiian Islands, and Didymosphenia
geminata, which is rapidly expanding in streams across
the United States.70,71.72,73
The primary issue regarding use of already-problematic
invasive plants for bioenergy production is whether such
uses will contribute to reducing the species’ invasion and
restoring the invaded ecosystem, or whether potential
economic gains from their use will encourage efforts to
maintain their presence on harvested landscapes, or
even lead to their cultivation and expansion into new
areas. In fact, some researchers suggest that, instead of
reduction, continued cultivation of the invasive species is
acceptable, particularly in cases where the plants have
become “naturalized” and where restoration to prior
ecosystem composition and/or function is no longer
feasible or possible – such as with Chinese tallow.74
However, Davis et al. (2010) describe such proposals as
a “Faustian bargain, with inadvertent creation of a lobby
dependent upon maintenance of infested areas for fuel
and employment.”75 It would likely be difficult for the
bioenergy industry to refrain from supporting expansion
of these feedstocks into new areas. Another issue of
concern is that the active use of invasive feedstocks
for bioenergy not only creates a sustained source of
origin for propagules, it also creates a transportation
infrastructure associated with harvest and use for
bioenergy, which will undoubtedly increase the pathways
for spread into other areas.
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Soil erosion due to flooding. Climate change is likely to contribute to an increase in extreme events such as flooding, which can help
spread invasive species long distances. Credit: NRCS.
Furthermore, efforts focused specifically on reduction
and control of currently-problematic plants must contend
with the fact that the use of the particular feedstock is
not sustainable – once the resource is depleted, other
feedstocks will be necessary to continue to support
bioenergy production. A potential avenue to get around
this dilemma would be through the creation of mobile
bioenergy production facilities, which could move
locations once a particular invasive species has been
harvested and processed. Mobile production units
may also help to reduce the risk of invasion created
by transportation of invasive feedstocks. A number
of companies are currently investigating this type of
technology. Another idea is to purposefully establish a
non-invasive, vigorously growing bioenergy feedstock in
an area on which an invasive has been removed, thus
preventing the invasive from becoming re-established
and ideally stopping its spread. This idea would be
particularly appropriate for areas in which the invasion
has destroyed much of the native vegetation and the
wildlife habitat value has been depleted.
Adding Climate Change to the Mix
Climate change is another issue that must be considered
when assessing the potential invasiveness of bioenergy
feedstocks. While bioenergy is often touted for its
potential to help mitigate climate change by reducing
net CO2 emissions, it is important to recognize that
changes in the earth’s climate system are already
underway and will continue into the future, even under
the best case scenario for mitigation. Several factors
associated with climate change are likely to exacerbate
the invasiveness of some bioenergy feedstocks. For
example, studies have found that some invasive species
may have a competitive advantage in systems disturbed
by extreme events such as floods, droughts, hurricanes,
and wildfires.76 Scientists project that climate change will
contribute to an increase in the frequency and intensity of
such events in the coming decades.77 Although impacts
will vary across different regions, understanding where
and how these changes might occur can help determine
whether certain feedstocks under consideration for
bioenergy production might have a potential to become
invasive as conditions warrant. For example, the
spread of several invasive species, including giant reed,
saltcedar, and Eurasian watermilfoil, has been directly
tied to flooding events, whereby their propagules can
travel over long distances downstream – well beyond the
capacity of land owners to control them.78,79
Furthermore, climate-related variables such as minimum
winter temperatures often serve as a natural barrier to
the expansion of invasive plants and animals into areas
that are climatically unsuitable for them. Indeed, climate
change is already contributing to an increase in average
temperatures across the United States. Reflecting this
change, the U.S. Department of Agriculture (USDA)
recently issued the first revision since 1990 of its map
of plant hardiness zones,80 showing a shift markedly
northward, consistent with climate change. In some
areas, these changes may enhance the ability for
potentially invasive plants to thrive where they may not
have in the past. For example, recent research suggests
that climate change is likely to contribute to a 2- to 10fold increase in highly suitable habitat for saltcedar in the
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
10
Northwest.81 Identifying areas with a suitable “climate
niche” is one of the primary factors that managers will
need to assess when locating bioenergy crops.82 It will
be important to consider not only the existing climate
conditions, but also how climate change is likely to affect
an area’s future climate and thus its long-term suitability
for specific biomass plants.
Another wild card is how competitive relationships
among plants will change with increases in atmospheric
CO2. Several of North America’s most noxious weeds,
including Canada thistle (Cirsium arvense), spotted
knapweed (Centaurea stoebe ssp. micranthos),
cheatgrass (Bromus tectorum), leafy spurge (Euphorbia
esula), and kudzu are more likely to benefit from changes
in atmospheric carbon dioxide concentrations than are
native plants, thereby giving them another competitive
advantage.83,84 As a general rule, plants with the C3
photosynthetic pathway (a trait associated with most
trees and shrubs, and some grasses and sedges) are
more likely to have enhanced growth from elevated
CO2 than plants using the C4 pathway (including many
feedstock candidates), assuming adequate water and
nutrients for growth. However, the C4 photosynthetic
pathway more efficiently uses water under warmer, drier
conditions than C3 plants. In areas where climate change
is projected to contribute to an increase in temperatures
and more extreme droughts, conditions for the C4
candidate feedstocks may become more favorable.
Selective Breeding and
Genetic Modification
Another issue of concern is the use of genetic
modification (GM) and selective breeding to enhance
or alter various characteristics, such as tolerance to
cold, flooding, or salinity, for both non-native and native
feedstocks, modifications that some studies suggest
could significantly increase the risk of invasiveness.85,86,87
In the agricultural industry, selective breeding and GM
have been used for a number of purposes, including:
increasing yield; enhancing nitrogen-use efficiency;
and increasing resistance to conditions such as
droughts, cold temperatures, pests, and diseases – all
characteristics that can give plants a competitive edge
over non-altered, native plants.88,89 Additionally, GM is
increasingly being used to alter the fertility of plants in an
effort to ensure that the plants are sterile. The purpose
11
of sterility is both to limit the chance of the GM plants
or their genes spreading outside of the area in which
they are being cultivated, and to ensure that farmers will
continue to purchase seeds for the modified crops.
...GM and conventionally altered
plants may pose a contamination
risk to the native ecosystems where
they reside, should the modified
versions spread.
There is considerable concern that GM and
conventionally altered plants may pose a contamination
risk to the native ecosystems where they reside,
should the modified versions spread. Research on the
potential impacts of modified species that become
established outside of target areas is still in its infancy,
and considerable uncertainty remains about the risks that
these species may pose relative to their wild relatives.
Just as non-native species are not all necessarily
invasive, modified plants do not all necessarily pose
a risk to native ecosystems. The risk depends on the
specific characteristics of the plant, where it is being
cultivated, and whether wild relatives of the plant are in
the region, among other considerations. One study of
the use of GM poplars as a biofuel feedstock suggests
that the scope of the ecological issues expected from
their use is likely to be no greater than for “conventional
plantation culture.”90 Other studies indicate that the
risks are likely much greater in cases where non-native
species are modified to improve their adaptability in areas
where they might otherwise not be able to survive.91,92
That is because modified plants may be able to breed
with wild relatives, resulting in potentially-invasive hybrids.
In fact, research has found that hybridization between
varieties or disparate source populations may promote
evolutionary changes that enhance the invasiveness of
exotic species over time.93,94 Hybrids are particularly
likely to occur in cases where there have been multiple
introductions of a species or variety into a new area
and where invasiveness has occurred after a lag period
during which hybridization could occur.
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Genetic modification has been used for many years for
food crops, and thus it may be useful to look to these
plants to better understand potential risks that GM
may pose to ecosystems. According to a Government
Accountability Office report, as of 2008 there were half
a dozen documented cases in which GM crops were
released into food, animal feed, or the environment
unintentionally, but the total number of unauthorized
releases into the environment was unknown.95 In a more
recent incident that was not included in the report, a
study found that herbicide resistant GM canola (Brassica
napus) has been found growing along roadsides
across North Dakota. Almost half of the roadside plants
sampled for the study were GM canola, indicating that
not only had the plants escaped from the areas in which
they were cultivated, but that they had become quite
common. Additionally, the researchers found that the
escaped plants could hybridize with each other, creating
entirely novel combinations of transgenic traits.96 Other
studies have documented the transmission of the
herbicide-tolerance gene from GM canola to wild
relatives of the crop, such as wild turnips (Brassica rapa
ssp. sylvestris).97
The Myth of Total Sterility
One way to reduce the risk of invasiveness is by
promoting plant species that are unable to breed
naturally. This can be achieved through several different
means, one of which is to alter the fertility of the
plants through genetic modification. In the case of GM
eucalyptus, for example, scientists spliced in a gene
known as the “Barnase gene” to limit the ability of the
trees to reproduce; eucalyptus trees with the Barnase
gene produce flowers without viable pollen.98 Other
times, companies rely on using hybrids between two
species. Hybrids between two plant species in the
same family are often sterile – but not always. In fact,
there have been a number of cases where species that
were thought to be sexually sterile have nonetheless
produced viable seed and become significant invaders.99
Sterility can, in fact, break down and a very small
number of viable seeds could be formed.100,101 Even if
this percentage is very small, the chance of reproduction
may become significant when considering the fact that
these species may be planted on a large scale. Giant
miscanthus (Miscanthus x giganteus), for instance, is a
sterile hybrid that is likely to be planted on hundreds of
Genetically modified canola plants have been found to escape
from the fields where they are cultivated.
Credit: Karl Naundorf/Bigstock.com.
...by scaling up, we are also scaling up
the chances of the “sterile” plant being
able to create enough viable seeds that
they may enter into nearby ecosystems.
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
12
thousands of acres in the next few years102 – by scaling
up, we are also scaling up the chances of the “sterile”
plant being able to create enough viable seeds that they
may enter into nearby ecosystems. As Low et al. (2011)
explain, “The large scale of proposed biofuels plantings
will ensure high propagule pressure, so that even plants
with low invasion potential will have many opportunities
to escape.”103
Indeed, there have been a number of examples of
so-called sterile plants becoming invasive. Townsend’s
cordgrass (Spartina x townsendii) was a sterile hybrid
developed in England that after a number of decades
began producing fertile plants.104 Similarly, the Bradford
pear (Pyrus calleryana), which was thought to be sterile,
ended up reproducing by seed and becoming invasive
through cross-pollination with other cultivars; individual
cultivars are not invasive themselves, but different
cultivars within a region can combine and produce
invasive plants.105 In 1994, the Bradford pear was
considered to have a very low invasion potential, but
after 10 years of ornamental plantings, it was found to
have invaded natural areas in at least 26 states. The
species is now considered an invasive plant in at least six
states, although it is not yet listed as a noxious weed in
any U.S. state.106
It is important to recognize that even if a plant is unable
to create viable seeds, it is not necessarily incapable
of reproduction. Many plants are very capable of
reproduction through the growth of new plants through
vegetative means, such as underground rhizomes.
For example, giant reed plants do not produce viable
seeds, but they propagate vegetatively (a form of asexual
reproduction in which a new plant can grow from a part
of the parent plant) from even small stem fragments – a
trait that enhances invasiveness.107,108 Giant miscanthus,
another sexually sterile plant, can spread through
underground rhizomes, although the rate of spread is
considered to be quite low.109
Feed stocks of concern
At least a dozen species of concern currently are being
used or considered for use as bioenergy feedstocks in
the United States. The following are just a few examples
of some of these species. While not exhaustive, this list
highlights some of the potential benefits as well as the
risks – both ecological and economic – that we must
consider as we continue to build our bioenergy economy.
Although the Bradford pear was thought to be sterile, the trees have become invasive in a number of states. Credit: Kenneth
Keith Stilger/Bigstock.com.
13
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Giant Reed (Arundo donax)
G
4
Case Studies
iant reed (Arundo donax), also known as giant
cane, is a large, fast-growing grass species native
to India. This perennial grass can grow between 9
and 30 feet tall.110 Originally introduced into the United States
in the 1800s for erosion control and windbreaks, giant reed
has become a nuisance weed in many states. However, its
fast growth and high yield have led to its consideration as
a biomass feedstock, and a number of projects across the
country are underway and others have been proposed, despite
the plant’s invasiveness.
Biomass Potential
Because it is fast growing and hardy, giant reed is considered
to be a high quality source of biomass, with the potential to
generate more than 20 tons of biomass per acre within two
years of initial planting. In some warmer areas, such as the
Aerial view of Arundo donax invading riparian areas near Big
Bend National Park, Texas. Credit: John Goolsby, USDA.
Gulf Coast, the plant may produce as much as 35 tons per
acre.111 In addition to its high yield, giant reed can remove
vegetative nodal fragment of giant reed floating downstream
toxins from the soil, and so may have the added benefit of soil
can become established and form a large weedy stand.120
or remediation in degraded or polluted lands.112
Giant reed has been ranked as a likely invasive species on at
Invasive Status and Risk of Spread
Researchers applying one such WRA to giant reed in Florida
Giant reed is considered to be an invasive plant in much of
crop, saying that “The combination of widespread distribution
its introduced range around the world; in fact, it has been
of giant reed propagules and inherent weedy characters
listed as one of the world’s 100 worst weeds.113 In the United
greatly increases the likelihood of escape and subsequent
least three published weed risk assessments (WRAs).121,122,123
concluded that the plant should be rejected for use as a biofuel
States, giant reed is listed as a noxious weed in Texas,114
environmental damage.”124 Furthermore, it is unknown how
California,115 Colorado,116 and Nevada.117 It has been noted as
propagules may be spread in hurricane-prone regions of the
either invasive or a serious risk in New Mexico, Alabama, and
country, where much of the production is proposed.
South Carolina.118 Giant reed in North America is not known
to produce viable seeds, so technically it is considered to
Potential Impacts
be sterile. However, the plant can spread through vegetative
reproduction, either through underground rhizomes or, more
Because giant reed plants need lots of water, they commonly
often, through culm (stem) fragments, which can grow roots
invade riverbanks, riparian areas, and floodplains, competing
and form new clones.119 Plant fragments can easily travel long
for scarce water supplies. In California as well as Texas, giant
distances downstream during storms, or become established
reed has formed virtual monocultures along streams and rivers,
along roadways after the grass has been harvested and
choking out native vegetation.125 Close to 30,000 hectares of
is being transferred for processing. In fact, even a small
riparian land in Texas are now estimated to be dominated by
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
14
giant reed.126 In California, a number of at-risk species, such
North Carolina: ChemTex International, LLC is currently
as the Least Bell’s Vireo (Vireo bellii pusillus), Southwestern
pursuing plans to cultivate giant reed and giant miscanthus for
Willow Flycatcher (Empidonax traillii extimus), and Yellow-
use as a biomass feedstock in North Carolina. The company
billed Cuckoo (Coccyzus americanus), could be significantly
applied for a loan guarantee under the Biorefinery Assistance
impacted by the displacement of native riparian vegetation
Program for construction and operation of a biofuels refinery
127
by giant reed.
Giant reed also provides less shade to
in Sampson County, North Carolina. According to the
streams than native woody vegetation, which can lead to
environmental assessment for the project, approximately 15-
increased water temperatures and invasion of other aquatic
20,000 acres would be used for growing giant reed and/or
plants, in turn affecting the habitat quality for aquatic wildlife
giant miscanthus, with a production capacity of approximately
128
species.
Additionally, leaf litter in streams from giant reed
20 million gallons a year.137 Additionally, the U.S. Environmental
that has invaded streambanks can lead to lower growth rates
Protection Agency (EPA) recently issued a direct final ruling
of aquatic invertebrates.129
in response to a petition from Chemtex allowing giant reed
Current or Planned Biomass
Uses and Risks
to qualify as a cellulosic biofuels under the Renewable Fuel
Standard.138 After environmental groups, including the
National Wildlife Federation, submitted public comments
raising concerns that the agency did not evaluate the invasive
Florida: Florida Statute 581.083 limits cultivation of nonnative
potential of the feedstock, EPA issued a notice withdrawing
plants, including GM plants, for purposes of fuel production
the final rule. EPA is currently in the process of addressing the
or other non-agricultural purposes in plantings greater in
concerns through the full rule-making process.139
size than two contiguous acres.130 However, the state has
granted several notable exceptions via special permits. In April
Methods of Control
2010, the state of Florida approved one such permit to White
Technology, LLC, to allow the planting of 80 acres of giant
131
reed for biomass energy.
In January 2011, another permit to
Once it has invaded an area, controlling giant reed is difficult
and costly. Manual removal techniques alone are often
White Technology was approved for an additional 87 acres.132
not effective, as the plant has deep rhizomes from which
Another company, Biomass Gas and Electric has also been
it propagates. Chemical control using pesticides is usually
interested in planting the species in Florida – particularly along
necessary, which can create pollution problems, particularly
the Gulf Coast – and has been funding a research project on
since so much of the habitat in which the plant has invaded
“genetic improvement” on giant reed.133,134 Giant reed has
is near streams and rivers. Other techniques for control
already invaded native plant communities in several parts
include burning and biological control, though neither is very
of Florida. While it is not currently classified as an invasive
effective. Officials in a number of states are spending millions
species in the state (it is considered “naturalized”), as of 2006,
of dollars in an attempt to control the species. In California, for
it was reported to be growing outside of areas where it was
example, costs range between $5,000 and $17,000 per acre
purposefully cultivated in 23 of the 67 counties in the state.135
to eradicate the weed. Other estimates put that cost as high
as $25,000 per acre.140 While the net revenues for alternative
Oregon: Around 100 acres of giant reed have been
bioenergy feedstocks will vary considerably based on their
planted in eastern Oregon for use as a biomass energy
respective yields, input costs, and commodity prices, and time
feedstock at the Boardman Power Plant. Based on the
needed for the plants to reach maturity, the general range is
success of this project, Portland General Electric will consider
likely to be in the area of a few hundred dollars per acre per
planting as much as 70,000 to 80,000 acres of giant reed per
year, by comparison.141
year.136 The town of Boardman is located along the Columbia
River, which raises concerns given the plant’s ability to invade
riparian areas.
15
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Miscanthus (Miscanthus species)
A
round 15 perennial species of grasses make up
ability to reproduce vegetatively is a characteristic that is
the genus Miscanthus. Because of their ability
particularly associated with invasiveness.150 Because it can
to thrive on marginal, non-crop lands and their
resprout from rhizomes, giant miscanthus could potentially
fast growth rates, a number of these species have been
spread during storm events, via transport to and from
considered for their biomass potential, including Miscanthus
production fields (e.g. falling off of trucks), through irrigation
sinensis and Miscanthus x giganteus, also known as giant
ditches and other waterways flowing near tilled field margins,
miscanthus. Giant miscanthus, which has shown greater
or even through animals that uproot plants in the fields, or a
promise as a bioenergy crop in the United States, is a sterile
host of other potential pathways. Studies have found that giant
hybrid cultivar of two miscanthus species, Miscanthus sinensis
miscanthus has a fairly low rate of spread,151 and has been
and Miscanthus sacchariflorus.
given a low-risk Weed Risk Assessment score by at least two
sets of authors.152,153
Biomass Potential
Of much greater concern than plantings of sterile giant
Giant miscanthus has been widely grown in Europe for a
miscanthus is research that is currently underway to field test a
number of years as a bioenergy source. Research in the
variety of giant miscanthus that produces viable seed.154 Giant
United States has found that it is far more efficient than corn
miscanthus that produces fertile seeds would significantly
grown for ethanol and requires less land and inputs to grow.142
lower planting and establishment costs,155 but would also
Additionally, giant miscanthus grown in Illinois was found to
significantly increase the risk of invasion to an extent that is
produce higher yields than switchgrass, a native grass that the
wholly unknown – the wind could easily spread viable seed
U.S. Department of Energy (DOE) has identified as a promising
into natural habitats. Seed dispersal experiments with sterile
feedstock for cellulosic biofuel.143
giant miscanthus indicate that the seeds can travel at least 400
Invasive Status and Risk of Spread
meters in the wind.156 Given the invasive status of the parent
species as well as the fast growth rate, large seed dispersal
Miscanthus sinensis, the parent species of the giant
miscanthus, is listed as invasive species in Connecticut.144
Similarly, Miscanthus sacchariflorus, the other parent species
of giant miscanthus, is listed on the Massachusetts prohibited
plant list.145 The invasive potential of giant miscanthus is not
yet fully understood; large scale production and field-size trials
of the plant have only begun to be implemented in the United
States.146 Giant miscanthus has been cultivated in Europe for
over 30 years, and there have been no documented cases of
the plant unintentionally spreading or escaping cultivation147,148
While giant miscanthus is a sterile hybrid cultivar, there is still
concern that it could reproduce vegetatively. A number of
features of giant miscanthus make it an ideal invasive weed—it
has the ability to resprout from below the ground, it grows
rapidly, and it has efficient photosynthetic pathways.149 The
MIscanthus. Credit: Hazel Proudlove/Bigstock.com.
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
16
range, and low input requirements of the hybrid plant, the risk
crops in the form of a cost-share and annual payments for five
of invasion for seeded giant miscanthus could be quite high.
years.160 As part of the BCAP program, USDA is funding a
Additional study is particularly needed on the potential for
project sponsored by Aloterra Energy and MFA Oil Biomass LLC
seeded giant miscanthus to escape and become invasive.
to establish and produce 200,000 acres of giant miscanthus in
Missouri, Arkansas, Ohio, and Pennsylvania.161 After the final
The way that giant miscanthus plantings are established has
environmental assessment was published, USDA issued an
major implications for how likely it is to become invasive.
addendum for the project, stating that farmers must only use the
Current projects in the United States mostly use giant
Illinois clone of giant miscanthus, which is sterile. Additionally,
miscanthus that is vegetatively propagated, due to the fact
the addendum states that farmers must agree to a number of
that the seeds of the plants are sterile. However, this method
practices to reduce the potential for giant miscanthus to spread;
leads to expensive planting costs, so other possibilities are
for instance, farmers must monitor and report on the potential
being considered, including the creation of seed production
spread of giant miscanthus beyond the perimeters of the field,
fields which could be planted with the two parent species
and they must not plant giant miscanthus within 1300 feet of
of giant miscanthus, M. sinensis and M. sacchariflorus. The
any known M. sinensis or M. sacchariflorus plants to prevent
fields would then generate the hybrid giant miscanthus seeds,
cross-pollination.162 Additionally, the USDA recently released
157
which could in turn be planted by farmers.
The risk of viable
a draft environmental assessment for another BCAP project,
seed production by the giant miscanthus plants would still
sponsored by the company REPREVE Renewables LLC, to pay
be the same since they would still be sterile hybrid plants.
farmers to plant an additional 58,000 acres in Georgia, South
Although the fields will be harvested for seed before the seeds
Carolina, and North Carolina.163 All of these acres would be
disseminate, the creation of such seed production fields still
planted with vegetatively propagated giant miscanthus.
creates an invasion risk, particularly given the invasive nature of
In addition to the giant miscanthus projects, there are field
the parent species.
Potential Impacts
trials underway across the country of a seeded variety
of giant miscanthus. Mendel Biotechnology has created
the PowerCaneTM seeded miscanthus. The company is
Miscanthus sinensis can displace native grasses and
currently undergoing testing at sites across the country and
dominate roadsides and pastures, likely because of its
development trials in Georgia, Tennessee, Kentucky, Indiana,
ability to tolerate harsh conditions such as poor soils, cold
and California, as well as creating a series of best management
158
temperatures, and shade.
Studies have demonstrated that
giant miscanthus may be more efficient and have higher yields
than native, locally adapted varieties of switchgrass.159
Should seeded giant miscanthus escape into natural
protocols for monitoring, reporting, and eradication.164
Mendel is aiming for a commercial launch in 2014 or 2015.
Methods of Control
ecosystems, it is certainly possible that it could outcompete
native grass species.
Current or Planned Biomass
Uses and Risks
Giant miscanthus is only beginning to be planted in the United
States and the economic costs of eradication are not yet
known. Eradication studies indicate that 95 percent of the
aboveground biomass can be successfully eliminated
through spring tillage, followed by an application of the
In the spring of 2011, USDA made several announcements
herbicide glyphosate; however, complete control of mature
regarding funding for projects to grow biomass feedstocks
stands of giant miscanthus are likely to require more than
through the Biomass Crop Assistance Program (BCAP), which
one growing season.165
was established as part of the 2008 Farm Bill. The program
provides financial assistance to farmers in establishing energy
17
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Genetically Modified Eucalyptus
(Eucalyptus grandis x Eucalyptus urophylla)
N
ative to Australia, eucalyptus trees are extremely
eucalyptus species have a potential to produce over 15
fast growing, making them a potentially ideal
dry tons of biomass per acre per year. Within 27 months,
source for woody biomass. However, many of the
eucalyptus trees can grow as high as 55 feet - which is
varieties of eucalyptus that are highly productive are very
extremely fast, particularly when compared with the pine
sensitive to freezing temperatures, particularly when they occur
plantations that are currently growing in the Southeast.168
as cold snaps rather than as progressively colder temperatures
in a winter season. To get around this problem, researchers
Invasive Status and Risk of Spread
have genetically modified eucalyptus to improve the trees’
tolerance of cold temperatures as well as droughts.166 These
Genetically modified hybrid eucalyptus has not been grown
genetically modified, hybrid eucalyptus trees (Eucalyptus
in the United States until recently; the invasive potential of the
grandis x Eucalyptus urophylla) also include a gene splice that
species is unknown. One of the parents of the hybrid species,
restricts the ability of the trees to reproduce.
Eucalyptus grandis, is “predicted to be invasive” according
to an assessment by the University of Florida.169 Additionally,
Biomass Potential
a number of other eucalyptus species are invasive in parts
of the United States, including Eucalyptus globulus, which
Certain eucalyptus species make ideal woody energy crops
is listed in the California Invasive Plant Inventory.170 Because
because they have high biomass productivity, a short rotation
GM eucalyptus trees are spliced with a gene that restricts
time, and relatively high levels of cellulosic carbohydrates
their ability to reproduce, the companies that are producing
(the primary resource for energy production).167 Some hybrid
the trees believe that there is little to no risk that the trees will
Eucalyptus trees in Hawaii. Credit: Mike Brake/Bigstock.com.
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
18
become invasive and overtake natural forests. Yet field trials
are just beginning for these trees, so there is no real proof that
the trees and their offspring will be 100 percent sterile.
Upon granting the biotech company ArborGen a permit to
begin field trials of GM eucalyptus trees in the southeastern
United States, the USDA issued a Finding of No Significant
Impact on the environment, noting in particular the small
scale of the field trials and the specific conditions necessary
for tree growth.171 However, thousands of comments were
submitted to the agency expressing concern about the
potential environmental impacts of genetically modified
eucalyptus, including comments from the Georgia Department
of Natural Resources opposing the project in part because
of concerns about invasiveness.172 One such concern is
whether there is a chance for the transfer of the cold-tolerance
gene to non-sterile varieties of eucalyptus, which would
increase its potential to inhabit areas previously considered
too cold. While the conditions associated with gene transfer
are complex and uncertain and would likely depend on the
mechanism of sterility, the potential for such hybridization is not
unprecedented between GM crops and their wild relatives.173
Potential Impacts
Because so little is known about GM eucalyptus, the potential
impacts on biodiversity should the plants escape into the wild
are uncertain. One concern is the potential for increased and
widespread forest fires should the GM eucalyptus become
widespread, due to the fact that the oils in eucalyptus trees
may make the vegetation flammable and the bark of many can
form fire brands that can spread fire far beyond the flaming
Current or Planned Biomass
Uses and Risks
In 2010, the USDA granted a permit to ArborGen, LLC to
grow GM eucalyptus trees in field trials on 330 acres in 28
sites. The sites are spread out in seven states throughout
the south: Texas, Louisiana, Alabama, Mississippi, Florida,
Georgia, and South Carolina. This permit is in addition to a
previous permit given to Arborgen to grow GM eucalyptus on
37 acres on 15 sites in the same seven states.177 The new
permit was granted after the USDA’s Animal and Plant Health
Inspection Service (APHIS) completed an environmental
assessment for the controlled field trial and issued a Finding of
No Significant Impact.178 A number of environmental groups
who were concerned that the environmental assessment was
not thorough enough took legal action against the USDA, but
the action ultimately failed.179,180 Additionally, it should be noted
that multiple other non-GM species and hybrids of eucalyptus
are being developed for cultivation particularly in the southeast,
some of which may be potentially invasive.
Methods of Control
Because genetically modified eucalyptus has not yet been
widely adopted, the economic costs of control are unknown.
However, invasions by other species of eucalyptus have been
costly and difficult to control. For example, efforts to eradicate
Eucalyptus globulus through logging and other measures in
Angel Island State Park in California took ten years; however,
with logging and herbicide treatments, along with extensive
restoration of native communities, the efforts were successful.181
front.174 Additional concerns have been raised that widespread
invasion or plantings of GM eucalyptus in the southeast
could have serious hydrological impacts, including altered
groundwater levels and/or stream flow, which could potentially
impact aquatic and terrestrial species.175 Furthermore, some
eucalyptus species are known to have allelopathic qualities
(i.e., they produce chemicals that impede the germination
and growth of surrounding vegetation), which would limit the
potential value of groves as wildlife habitat.176
19
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Reed Canarygrass (Phalaris arundinacea)
Reed canarygrass invading a riparian area in Alaska. Credit: Tom Heutte, USDA Forest Service, Bugwood.org.
A
native of Europe, Asia, and North Africa, reed
canarygrass was first introduced to the Pacific
Northwest in the early 1900s. Over the years, this
Biomass Potential
Reed canarygrass is a particularly hardy species due to its
tall perennial grass, which can reach up to heights of nine feet,
ability to grow in wet soils and to tolerate droughts better
has been used as a “breaking in” crop to help prepare former
than most wetland species.184 Combined with high yields (in
forested land for cropping, as forage for livestock, and more
some states it has been found to produce higher yields than
recently as a water management tool.182 There are different
switchgrass) reed canarygrass is a particularly good candidate
ecotypes of reed canarygrass, and some speculate that there
for biomass production.185 Additionally, reed canarygrass is
may be an ecotype of the species that is in fact native to parts
a cool-season grass, while many other grasses cultivated for
of the northwest United States, although there has not been
biomass like miscanthus and switchgrass are warm season
scientific consensus on the issue.183
grasses. Thus, it can be harvested in early summer when
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
20
warm-season grass biomass is not available, allowing for a
186
more constant biomass supply for a region.
potential in the Eastern Upper Peninsula (EUP) of Michigan,
for instance, looked at both the use of currently existing acres
Invasive Status and Risk of Spread
of the invasive weed as well as the possibility of planting more
and concluded that, “Reed canarygrass thus represents an
economic potential for the EUP both in terms of reducing
187
Reed canarygrass is currently present in 43 U.S. states.
fuel costs and providing another source of income for area
It is considered to be an invasive or noxious species in three
farmers.”197 Reed canarygrass has also been tested for use as
188
states: Connecticut, Massachusetts, and Washington.
a biomass feedstock in Pennsylvania,198 Ohio,199 Wisconsin,200
Researchers at the University of Vermont have described reed
and Iowa,201 among other places.
canarygrass as “one of the most noxious invasive species
in North American wetlands, rivers, and lakes.”189 Reed
Methods of Control
canarygrass can spread through seeds or plant fragments, or
vegetatively through rhizomes. The latter pathway is typically
Because it is such a hardy species, reed canarygrass is
credited for its remarkable ability to spread. Reed canarygrass
particularly expensive and difficult to control. It is resistant to
spreads particularly well in disturbed areas, although it has also
burning and flooding202 and has an abundant seedbank that
been known to invade native wetlands.
can last for years.203 Typical management regimes to eradicate
Potential Impacts
stands of reed canarygrass include a combination of hand
pulling, mowing, burning, and chemical treatment over a few
years, followed by monitoring for many more years.
Reed canarygrass can be particularly problematic in wetlands
and disturbed areas, outcompeting native species, forming
dense mats, clogging shallow streams and ditches, and even
impeding water flow.190,191 Once it has taken over wetland
areas, the dense stands offer poor quality habitat for wildlife,
such as waterfowl, that depend on wetlands for cover, habitat,
and food.192 Reed canarygrass is estimated to have invaded
thousands of acres of wetlands throughout the country.193 The
weed is a particular problem for wet meadows in the Upper
Midwest, where the grass forms dense monocultures and
shades out native grasses and forbs.194 Native species that
begin to grow in the late spring are particularly impacted by
reed canarygrass.195
Current or Planned Biomass
Uses and Risks
Reed canarygrass is currently being cultivated on thousands
of acres for biofuel production in Europe,196 but it has yet
to be adopted in the United States as a biomass feedstock
in any capacity beyond research studies. However, there
have been a number of studies devoted to assessing the
potential of growing reed canarygrass in the United States for
bioenergy production. A study looking at the weedy plant’s
21
A field of reed canarygrass. Credit: Chris Evans
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Algae
O
ne of the fastest growing fields in biofuels research
approximately two dozen
is that of algae, including both microalgae (small
non-native macroalgae
unicellular organisms, including diatoms and
species found in Hawaiian
cyanobacteria) and macroalgae (e.g. seaweeds such as
204
Laminaria, Sargassum, and Gracilaria species).
This
waters, about half of which
are reported as invasive.212
explosive growth has been driven in large part by the federal
Statewide, the economic
government, particularly the DOE, which has invested
cost of controlling these
millions of dollars in algae biofuels research and created a
invasive algae is estimated
National Algal Biofuels Technology Roadmap towards the
at well over $20 million
commercialization of algal biofuels. Algae are especially
per year.213
promising sources of bioenergy because they do not require
soil or arable land for growth – rather, they are cultivated in
Given the vast number of
freshwater or saltwater, either in open-air ponds or contained
algae species in existence
systems. There are thousands of species of algae, and both
and the rapid pace of
native and non-native algae species are being considered as
algae research and
205
biomass feedstocks in the United States.
Additionally, there
genetic modification, there
Algae being processed for biofuel.
Credit: Sandia National Laboratories.
has been considerable interest in genetically modifying algae
is very little known about
to optimize biofuel production.206
the invasion potential of the species that are currently being
cultivated in labs and commercial facilities. However, several
Biomass Potential
traits specific to algae suggest the potential for invasiveness.
For example, microalgae can easily aerosolize and spread,
Algae are being evaluated and tested for use as a feedstock for
leading to a high potential for such algae to escape from a
production of starches for alcohol (i.e. cellulosic ethanol), lipids
biomass production facility; indeed, and there have already
for diesel fuel, as well as a source of hydrogen (H2) for fuel cells.
been cases of algae escaping into the environment from
Compared to terrestrial plants used for biomass, both microalgae
research labs.214 Natural strains of algae from a California-
and macroalgae more efficiently convert solar energy into usable
based bioenergy company, for instance, “have been carried
energy.207,208 For example, per unit area, microalgae can produce
out on skin, on hair, and all sort of other ways, like being blown
up to 250 times more oil than soybeans. According to some
on a breeze out the air conditioning system.”215 According to
researchers, “…(p)roducing biodiesel from algae may be the
a researcher at University of Kentucky, “complete containment
only way to produce enough automotive fuel to replace current
of algae is completely impossible.”216 This raises particular
210
gasoline usage.”
Additionally, algae are a particularly attractive
concerns regarding the use of invasive, exotic, and genetically
feedstock for biofuels because some species can be grown in
modified strains of microalgae. While open ponds will likely
saltwater or wastewater, and can be used to produce a variety
pose considerably higher risk, even in a closed system, algae
211
of fuel types.
might be able to escape through ventilation systems or even
Invasive Status and Risk of Spread
on the clothes of workers. Macroalgae, which grow from
spores, also may be transported unknowingly to new areas
and remain dormant for some time before their growth is
A number of species of algae are listed on various invasive
spurred by favorable environmental conditions.217
species lists in the United States. For example, there are
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
22
Potential Impacts
Little research has been conducted on potential for nonnative or modified strains of algae cultivated for biomass
energy to escape into natural ecosystems, and the potential
impacts on biodiversity are not well understood. Proponents of
genetically modified algae believe that the risks posed to native
ecosystems are low and that the algae are unlikely to survive
or thrive outside of highly controlled labs or facilities. However,
the extraordinarily fast growth rate of algae as compared to
other genetically modified crops, combined with their ability to
adapt to a variety of environments, concerns many others.218
Should algae cultivated for biomass escape and become
invasive, the impacts on biological diversity, and particularly on
aquatic habitats, could be devastating. For example, across
the United States, the once-scarce Didyomosphenia geminata
(also known as Didymo and “rock snot”) has been rapidly
expanding in streams, where it grows into huge, slippery
mats that can expand the width of the river bed and crowd
out native plants. In addition, the non-native cyanobacterium
Cylindrospermopsis raciborskii (or Cylindro), another bioenergy
feedstock candidate, has been associated with toxic algal
blooms in the Great Lakes region.219 Introduced macroalgae
also can have significant impacts on native ecosystems and
can change community dynamics through high abundance
and monopolization of available space.220 The macroalga
Gracilaria salincornia, for instance, has become prevalent
throughout the coastal waters of Hawaii, where it has rapidly
overgrown and smothered coral reefs.221,222
Current or Planned Biomass
Uses and Risks
At least a dozen oil companies and government research
centers are currently working on genetically engineering algae
for renewable energy production,223 and many others are
working on creating renewable fuels from non-genetically
modified algae. There are also an assortment of different
types of projects being investigated, including both closed
systems and open air ponds, each of which carries different
risks. Unfortunately, it is not always possible to find out which
or non-native, and whether they are modifying the species.
Below is just a small sampling of some of the companies and
research facilities that are currently working on creating energy
from algae:
• University of Nevada, in conjunction with Enegis, LLC
and Bebout and Associates, created the first demonstrationscale algae to biofuels project in Reno, Nevada.224 While they
began their research using single-celled algae that grow in
saltwater, they now are experimenting with different types of
algae that can be grown in wastewater, with the idea that the
algae could both help to purify the wastewater and produce
renewable fuel.225
• Solazyme: One of the most well known and successful
algae energy companies is Solazyme, which recently signed a
contract, along with some partners, to supply the U.S. Navy
with 450,000 gallons of renewable fuels. The fuels will be made
from used cooking oil as well as algal oil from Solazyme.226
Using fermentation tanks, the company utilizes genetically
modified microalgae in the absence of light to convert sugars
from plant feedstocks such as sugarcane-based sucrose or
corn-based dextrose to create oil.227,228
• Aquatic Energy: Based in Louisiana, Aquatic Energy
has an open-pond, freshwater algae farm in southwestern
Louisiana that they use to create algal oil and meal, both of
which can be used by refineries to create fuels. According
to their website, the company uses non-genetically modified
“proprietary algae strains, which are domestic and natural.”229
Methods of Control
Should a species of algae become invasive and begin to affect
biodiversity or lead to economic losses, the cost of eradicating
the invader could potentially be considerable. For example,
in southern California, the cost of eradicating one invasive
marine macroalga, Caulerpa taxifolia, from one lagoon was
approximately $3.34 million and took over five years.230 In
most cases, eradication of invasive algae probably is not even
technologically feasible.
species a company is cultivating, whether the species is native
23
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Napiergrass (Pennisetum purpureum)
N
apiergrass, also called elephant grass, is a tall,
clump-forming grass native to Africa. The plant has
been introduced in many tropical regions for use as
a forage crop for livestock grazing, given its ability to quickly
produce large amounts of biomass.231 It was introduced in the
early 1900s to areas of Texas and Florida and promoted by the
Bureau of Reclamation as a forage crop,232 but since then it has
become a highly troublesome weed.
Biomass Potential
As with other fast-growing, rhizomatic grasses, napiergrass is
considered a “premier biomass plant.”233 In the 1980s, it was
used as a feedstock for methane generation and also was
co-fired with coal to produce electricity. Today, it is seen as
Napiergrass being cultivated in Florida. Credit: Julie Sibbing.
a promising feedstock for cellulosic ethanol. In north-central
Florida, it has yielded as much as 20 tons per acre per year in
and it can grow very quickly. Because napiergrass is freeze-
dry biomass, depending on available rainfall and fertilization. In
intolerant, its potential spread (and use for bioenergy) is limited
addition, it can be harvested twice a year, making it particularly
to southern regions.
useful as a dedicated energy feedstock. Research is currently
underway to try to develop “non-invasive, genetically improved
Potential Impacts
genotypes” of napiergrass through elimination or reduction of
gene dispersal of the species by pollen and seeds.234
Napiergrass is an invader of a number of different types of
habitats and disturbed areas, including canal banks, fields, lake
Invasive Status and Risk of Spread
shores, swamps, croplands, and prairie habitats.241 Because
of its dense growth, the grass prevents regeneration of native
Napiergrass has been identified as one of world’s most
species by crowding out grasses, herbs, and tree seedlings.242
problematic weeds and is listed as a category 1 invasive
Additionally, the dense growth of napiergrass can reduce water
235,236
species by the Florida Exotic Pest Plant Council.
Category 1 species are defined as “Invasive exotics that are
altering native plant communities by displacing native species,
changing community structures or ecological functions, or
flows and block access to canals.243
Current or Planned Biomass
Uses and Risks
hybridizing with natives.”237 Napiergrass has been documented
in nearly 30 counties throughout the state, where it has taken
Vercipia Biofuels, owned by BP Biofuels North America, has
over areas of canal and ditch banks, blocking access and
plans in the works to build what they believe will be the first
238
impeding water flow.
Napiergrass was ranked as having
a high probability of becoming invasive on at least two
239,240
published weed risk assessments (WRAs).
Napiergrass
can reproduce both vegetatively and through seed dispersal,
commercial-scale cellulosic biofuels production facility in the
country. Located in Highlands County, Florida, the facility
will use a variety of different perennial feedstocks, including
napiergrass.244 They are currently developing a seed farm to
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
24
Napiergrass. Credit: Dan Clark, USDI National Park Service, Bugwood.org.
ensure sufficient quantities of the feedstocks.245 According to
the EPA, continued development of napiergrass as a bioenergy
Methods of Control
crop is likely throughout much of Gulf Coast region, including
The only ways to control napiergrass invasions are through
Florida and southern portions of Texas, Louisiana, Georgia,
mechanical or chemical means; however, because
Alabama, and Mississippi.246 Additionally, the EPA had recently
napiergrass can spread easily via vegetative cuttings, tillage
issued a direct final rule that would allow napiergrass (in
is not recommended. In fact, according to researchers at
addition to giant reed) to qualify as a cellulosic biofuels under
the University of Florida’s Institute of Food and Agricultural
the Renewable Fuel Standard.247 However, after environmental
Sciences (IFAS) Extension, “cultivation can actually cause
groups submitted public comments raising concerns that
larger infestations of napiergrass by breaking mature plants
the agency did not evaluate the invasive potential of the
into pieces and distributing them throughout the field.”249
feedstocks, EPA issued a notice withdrawing the final rule. EPA
According to a researcher at the USDA, it is precisely because
is currently in the process of addressing the concerns through
the species is so difficult to control and eradicate that it has
the full rule-making process.248
become such a nuisance in tropical areas.250
25
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
5
Minimizing
the Risks
The Importance of
Embracing Precaution
As investments in bioenergy continue to grow,
maximizing the benefits and minimizing the costs and
unintended consequences associated with bioenergy
development will be a key challenge. As this report has
shown, the potential ecological and economic costs that
would come if bioenergy feedstocks escape and become
invasive are likely to be considerable. Yet, all too often the
long-term costs associated with invasive species are not
realized until it is essentially too late to avoid them. The
potential for irreversible harm underscores the paramount
importance of taking a precautionary approach.251
America must strive to better understand the risks
of invasions from current and proposed bioenergy
feedstocks and to focus our strategies – first and
foremost – on prevention. Most critically, crops that are
currently invasive or pose a significant risk of becoming
invasive should not be cultivated as bioenergy feedstocks
without comprehensive mitigation strategies in place
that greatly reduce the risk of escape and invasion.
It is important to note that non-native and genetically
modified feedstocks are not the only options available for
bioenergy production. For example, using mixes of noninvasive plant species that are local to the region where
they are being proposed for cultivation is a promising
way to reduce the risk of invasion while still allowing for
profitable bioenergy production (see Box 2).
Current Regulation of
Invasive Species
Switchgrass, a native grass, being harvested for bioenergy.
Credit: Oak Ridge National Laboratory.
America must strive to better
understand the risks of invasions
from current and proposed bioenergy
feedstocks and to focus our strategies –
first and foremost – on prevention.
In order to identify ways in which we can better reduce
the risks from invasive bioenergy feedstock development,
it is useful to understand the primary federal and state
policies and programs governing invasive species
26
Box 2. Creating Energy from Native Plants
N
ot all bioenergy companies are focusing on
non-native feedstocks. There are a number of
promising projects using native, locally adapted
species as feedstocks. Other projects use sustainably
harvested wood from forests or rely on waste and
byproducts from manufacturing operations.
Show Me Energy
The Show Me Energy Cooperative, based in Missouri,
offers a great example of how growing native plants for
bioenergy can be both profitable and environmentally-
Native aquatic plants being grown for energy at Parabel.
friendly. Show Me Energy is a biomass cooperative
Credit: Julie Sibbing.
that is owned and operated by over 600 farmers in 38
counties in Missouri and Kansas. These farmers collect
from the aquatic plants is in the form of biocrude, a type
residues from common agricultural crops, and also
of oil made from biomass which can be converted into a
plant native perennial crops on 50,000 acres of marginal
number of different forms of energy.254 Parabel currently
land using the best conservation practices available,
has a commercial demonstration center in Fellsmere,
including using polycultures and timing the harvest
Florida, which has been in operation since 2009, and is
for the late fall to avoid bird nesting and brood-rearing
in the process of creating projects in Chile and Surinam
season. The grasses and legumes currently used for
using species that are local to the regions where the sites
the project include: big bluestem (Andropogon gerardii),
will be located.255
switchgrass, indiangrass (Sorghastrum nutans), Canada
wild rye (Elymus canadensis), Virginia wild rye (Elymus
virginicus), purple prairie clover (Dalia purpurea) and Illinois
bundleflower (Desmanthus illinoensis).252 In May 2011,
USDA announced that Show Me Energy would become
the first dedicated energy feedstock project funded under
the Biomass Crop Assistance Program.
Middlebury College Biomass Plant
In 2009, Middlebury College began operations of its $12
million biomass gasification boiler as part of a campus
plan to achieve carbon neutrality by 2016. The biomass
plant is fueled by wood chips – between 20 and 35 tons
are delivered per day – all of which come from wood that
Parabel
is harvested within a 75 mile radius of the campus. Most
of the wood chips are byproducts from local logging
Previously called PetroAlgae, the Melbourne, Florida-
operations or from mill waste. The biomass plant uses
based company Parabel uses “micro-crops” of tiny,
the wood to create steam, which then powers campus
non-genetically modified aquatic plants to create both a
heating, cooling, hot water, and cooking operations.256
renewable energy feedstock as well as a protein source
The college is also investigating other potential sources of
that can be used for animal feed and potentially as a
biomass, and is currently using test plots to determine the
253
human food.
30
27
The energy that the company creates
feasibility of growing willows near the campus.257
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
and genetically-engineered plants. Importantly, the
development of policies to address invasive species has
necessitated clear definitions of relevant terms, such as
“alien,” “exotic,” “non-native,” “invasive,” and “noxious
weed” as these terms often mean different things for
different people (see Box 3).
Federal Regulation of Plant Species
While the problems associated with invasive species
have long been a national concern, the federal laws that
currently address invasive species are generally a mixture
of diverse provisions and multiple jurisdictions, which
often lack coordination and consistency.263 In its 1993
assessment of the nation’s invasive species programs,
the Office of Technology and Assessment concluded
that “[t]he current Federal framework is a largely
uncoordinated patchwork of laws, regulations, policies,
and programs,” and that invasive species issues “often
receive governmental attention on a piecemeal basis
after major infestations” have occurred.264
Some of the most-developed laws regulating invasive
species are those associated with threats to agriculture
under the authority of the USDA, although there are also
several laws that address threats to other economic
sectors, as well as fish and wildlife. While a complete
review of existing policies and programs is beyond
the scope of this report, there are several key statutes
relevant for bioenergy feedstocks. For example:
Plant Protection Act of 2000. The Plant Protection
Act of 2000 (PPA) consolidated USDA authority over
noxious weeds and plant pests into a single statute.265
Importantly, the PPA expands the definition of noxious
weed, which previously had been defined under the
1974 Federal Noxious Weed Act, to include injury to the
“environment.”266 Inclusion of a species on the federal
Noxious Weed List prohibits subsequent movement
of the plant within the United States. The statute,
however, provides authority for prevention of noxious
weeds, but not eradication or remediation of already
established noxious weeds on private lands. Moreover,
terrestrial species are often not included on the federal
Noxious Weed List until harm is well documented and
the species is established over large ranges across the
United States.267 Although a 2004 amendment to the
Box 3. Some Common Definitions
Relevant to Invasive Species258
• Alien species. Generally defined as “species that
spread beyond their native range, not necessarily harmful,
or species introduced to a new range that establish
themselves and spread.”259 Similar terms include exotic
species, introduced species, and non-native species.
• Non-native species. One of the most commonly
used terms to describe plant or animal species not
originally from the area in which it occurs. May be defined
as “a species whose presence is due to intentional or
unintentional introduction as a result of human activity.”260
• Invasive species. This term is often the subject of
confusion and debate. Under Executive Order
11322, it is defined as “an alien species whose
introduction does or whose introduction is likely to cause
economic or environmental harm or harm to human
health.”
• Noxious weed. Defined in federal law261 and in
most state codes, denoting special status of a plant as
restricted or prohibited. Commonly defined as “native or
non-native plants, or plant products, that injure or cause
damage to interests of agriculture, irrigation, navigation,
natural resources, public health, or the environment.”262
As a general rule, plants designated as noxious have
regulatory restrictions, while other designations (e.g.,
invasive or non-native) do not.
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
28
PPA authorized USDA to provide financial and technical
assistance to state/local weed management agencies to
control or eradiate established weeds,268 Congress has
not appropriated funding for this program.
U.S. Executive Order #13112. Although USDA
has the primary responsibility for noxious plant species
control at the federal level, at least thirteen federal
departments and agencies exercise some authority
over invasive species. To coordinate these efforts, in
1999 the President established via executive order the
National Invasive Species Council (NISC).269 Specifically,
EO 13112 states: “Each Federal agencies whose
actions may affect the status of invasive species shall,
to the extent practicable and permitted by law…not
authorize, fund, or carry out actions that it believes are
likely to cause or promote the introduction or spread
of invasive species in the United States or elsewhere
unless… the agency has determined … that the
benefits of such actions clearly outweigh the potential
harm caused by invasive species; and that all feasible
and prudent measures to minimize risk of harm will
be taken in conjunction with the actions.” Importantly,
this executive order could apply to federal subsidies
directed to bioenergy crops that may have invasive
characteristics.270 The new emphasis on prevention
is important, as most prior efforts to address invasive
species largely focused on those that had already been
introduced into the country. However, the particular
challenge in addressing the potential invasiveness of a
bioenergy feedstock under the efforts established under
EO 13112 is how decision makers ultimately determine
the respective “benefits” versus the “costs” or “harm”
from its use.271
The Biomass Crop Assistance Program
(BCAP). Congress established BCAP as part of
the 2008 Farm Bill to provide assistance for farmers
transitioning to biomass crops.272 BCAP was the
first federal subsidy program for the production of
biomass.273 The program provides matching payments
for the collection, harvest, storage and transportation
of biomass (commonly referred to as CHST payments),
as well as separate payments for the establishment of
perennial biomass crops. CHST payments are available
for the collection, harvest, storage, and transportation of
existing invasive and noxious species,274 but USDA may
not provide establishment payments in support of any
plant that is noxious or invasive.275
29
State Regulation of Invasive Plants
State regulation of harmful plants dates back more than
a century, as many states recognized the threats that
noxious weeds posed to agriculture. Today, states still
bear the primary responsibility for the on-the-ground
prevention, control, and management of invasive species,
and each state government has developed unique and
diverse webs of authorities to address different species
and, to a lesser extent, invasion pathways.276
Typically, states use lists to identify species that should
be restricted and those that are considered safe. The
general rule has been the development of so-called
“black lists,” which regulate only species that have been
designated as problematic by the legislature or agency.
”White lists,” on the other hand, identify species that
the government deems “safe” – all other species are
presumed to be harmful unless they have undergone
a process to determine that they are not.277 Currently,
administrative agencies in forty-seven states (usually
departments of agriculture, but occasionally departments
of natural resources) have authority to add species to
Figure 1. Regulated plant species are
a function of both federal and state
noxious weed lists
State noxious
weed list
(varies by
jurisdiction)
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Federal noxious
weed list
(7 C.F.R § 360.200)
their respective state noxious weed list. However, lists at
the state level tend to be highly reactive—listing species
only after there is significant damage to agricultural
production or the environment. Additionally, state and
regional Invasive Plant Councils (IPC) or Exotic Pest Plant
Councils—consisting of weed ecologists, land managers
and other stakeholders—have the technical competence
to identify potential invasive plant species, but often do
not have an advisory role, much less actual authority, to
include these species on the state’s official noxious weed
lists. Demonstrating this disconnect between the IPCs
and the noxious weed lists, a recent study found that, on
average, official state noxious weed lists only included
19.6 percent of the species considered invasive by the
respective state invasive plant council.278 Only five states
(MA, CT, OR, NH, and WA) had noxious weed lists that
contained more than 50 percent of the invasive species
identified by the respective IPC.
of Florida’s Institute of Food and Agriculture Sciences
(IFAS), may exempt non-native biomass plantings
from the permit requirement if it determines that plant is
not invasive.
Conversely, because plant species have to be listed
as noxious or invasive plants or be determined to be
invasive to be denied permits, the permitting process
does not necessarily prevent the cultivation of potentially
invasive plants such as giant reed (Arundo donax)
or napiergrass (Pennisetum purpureum) that are not
listed on Florida’s noxious weed list, unless the bond
represents a sufficient disincentive that cultivation plans
are abandoned. A proposed statute in Mississippi would
enact a similar regulatory program, providing authority
for the Department of Agriculture to deny permits for
invasive plants or plants with the potential to constitute
a nuisance.280
The current multi-jurisdictional approach to noxious
weed regulation leaves many terrestrial invaders largely
unregulated at both the state and federal level, as these
plant species often are not included on either federal or
state noxious weed lists (see Figure 1). State noxious
weed lists, designed to supplement the federal list by
tailoring invasiveness to state-specific ecosystems,
generally fail to include known invasive plants. Moreover,
many states lack authority (or refuse to exercise their
power) to enforce state weed control laws on private
property. Civil liability for the spread of weeds onto an
adjacent landowner’s property also varies widely across
states, with some courts reluctant to require control over
“natural” plants. Accordingly, there is minimal incentive
for individual landowners to control noxious plant species
absent an impact on agricultural productivity.
Biotechnology Regulation
At least one state has been proactive in enacting a
regulatory program designed to address the potential
invasiveness of large-scale cultivation of bioenergy crops.
In 2008, Florida implemented a permitting requirement
for cultivation of non-native plants (including genetically
engineered plants) intended for biofuel production.279
Biomass plantings spanning more than two acres require
a permit from the Florida Department of Agriculture
and Consumer Services. The permit also includes a
bonding requirement, the proceeds of which would
fund eradication efforts of invasive bioenergy crops.
The Department, in consultation with the University
As is the case with invasive species, the regulation
of genetically-modified (GM) products is handled by
multiple agencies under multiple statutes.281 The United
States regulates the field testing and commercialization
of GM plants under a 1986 agreement known as
the Coordinated Framework for the Regulation of
Biotechnology (Coordinated Framework).282 This
complex, multi-agency agreement sets up a trifurcated
regulatory system, with oversight by: 1) the USDA
to prevent introduction of agricultural pests under its
Federal Plant Pest Act (PPA) authority;283 2) the EPA to
regulate pesticides incorporated into plant tissue through
The current multi-jurisdictional
approach to noxious weed
regulation leaves many terrestrial
invaders largely unregulated at
both the state and federal level, as
these plant species often are not
included on either federal or state
noxious weed lists.
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
30
its Federal Insecticide, Fungicide, and Rodenticide Act
(FIFRA) regulatory powers;274 and 3) the U.S. Food and
Drug Administration (FDA), via the Federal Food, Drug,
and Cosmetic Act (FFDCA),285 to ensure the general
safety of food and feed products produced with the use
of GM technologies.
USDA’s authority to review GM plants under the PPA
is premised on two statutory provisions: whether the
novel plant is a potential “plant pest” or a “noxious
weed.”286 Accordingly, USDA jurisdiction extends only to
plants regulated as plant pests or noxious weeds—not
every plant altered through genetic engineering. A GM
plant would fall under USDA plant pest jurisdiction if
the donor, recipient, vector or vector agent used in the
genetic engineering is listed as a plant pest in the USDA
regulations or there is otherwise reason to believe it is
a plant pest. If the GM plant is believed to be a plant
pest, introduction of the plant material may be allowed
without a permit, but only in accordance with specific
criteria to ensure that it is contained. Only after field trials
demonstrate no significant risk of invasiveness can a
company petition APHIS for non-regulated status.
Two recent USDA decisions discussed below illustrate
how GM bioenergy crops may avoid review under the
Coordinated Framework. In 2008, USDA determined that
a GM petunia (Petunia) modified to produce a novel color
was not subject to regulation under the PPA because
neither the recipient, donor, vector, nor vector agent was
a plant pest under existing regulations.287 As a plant not
intended for food or feed, the GM petunia also avoided
FDA review under the FFDCA. Moreover, as the plant
did not incorporate a pesticide or change the use of any
externally applied pesticide, the EPA lacked jurisdiction
to review the plant under its FIFRA authority. In sum, the
petunia slipped through a loophole in the Coordinated
Framework. In 2011, a variety of Kentucky bluegrass
(Pao pratensis) genetically engineered to tolerate the
herbicide glyphosate similarly evaded USDA review
under the PPA.288 Non-GM bluegrass was not listed as
a plant pest and the organisms used as a source for the
new genetic material to infer herbicide tolerance were
similarly not regulated as plant pests. The USDA also
rejected a parallel petition to regulate the GM bluegrass
as a noxious weed due to its herbicide resistance.289
Moving forward, to the extent that novel GM bioenergy
Not all genetically modified plants are subject to regulation in the United States. Credit: Sebastian Duda/Bigstock.com.
31
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
feedstocks follow the pathway carved by the GM
petunia and bluegrass petitions, and do not include
plant incorporated pesticides subject to EPA review, or
have residual uses as food or forage that may trigger
FDA’s jurisdiction (e.g., USDA currently is conducting
environmental assessments for eucalyptus trees
genetically engineered for cold tolerance290), many novel
dedicated bioenergy plants may forego the Coordinated
Framework entirely.
Screening Tools
The considerable ecological and economic threat
posed by invasive species has generated national and
international protocols to screen non-native species
being considered for human uses in order to evaluate
potential risks. For example, Australia has developed a
model weed risk assessment (WRA) system to screen
all new plants before they enter the country by applying
a “sieve” approach, which applies a set of questions
to determine potential invasiveness and then approves
some species, rejects others outright, and conditionally
rejects the rest.291,292 Nearly a dozen independent
studies found that the Australian WRA consistently
was able to identify invaders.293 Additionally, the use of
WRA has been found to provide net economic benefits
by allowing authorities to screen out costly invasive
species, even after accounting for potential revenues
lost if a small percentage of plants have been rejected
despite ultimately proving to be non-invasive.294 The
USDA has its own weed screening tool that is based on
the Australian WRA,295 and a similar WRA approach has
been developed specifically for aquatic plants.296
Screening potential bioenergy feedstocks with programs
like WRA is especially important because of the inherent
invasive qualities of many potential feedstock plants.297
For example, a study that applied the Australian WRA
approach in Florida and other areas of the United
States found that a majority of proposed bioenergy
crops analyzed present an “unacceptable” invasion
risk in their respective target regions.298 In addition, a
study that applied WRA to potential biofuel crops in
Hawaii suggests that, when compared to a sample of
introduced non-biofuel species, biofuel crops were twoto four-times more likely to be naturalized or invasive.299
Genetically modified Kentucky bluegrass is currently not subject
to regulatory review by USDA. Credit: NRCS.
While WRA has proven to be an important and effective
tool, several researchers suggest that some of the
more commonly-used risk assessment protocols may
not address all of the issues that might determine the
potential invasiveness of bioenergy crops, suggesting
that more rigorous, “multi-tiered” approaches should be
used – particularly in cases where initial analyses indicate
conditional rejection.300 This may not only help identify
species that are likely to be more problematic than initial
WRA may have indicated, but it also may help determine
where the risk might be lower than originally thought.
Davis et al. (2011), for example, found that additional
quantitative analysis of Camelina sativa, which would
have been rejected under the Australian WRA protocol,
indicated that its invasive potential is only a concern if it is
cultivated in areas with disturbed soils.301
Other factors that warrant explicit consideration in
WRA for bioenergy feedstocks include those related
to cultivation and management practices.302,303 For
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
32
Screening potential bioenergy
feedstocks is especially important
because of the inherent
invasive qualities of many
potential feedstock plants.
example, many biofuel feedstocks are harvested in late
fall, after they have produced seed. This enhances the
risk that the plants will be spread unintentionally when
the feedstocks are transported to storage or production
facilities.304 Invasive potential also may be enhanced
if biomass crops are planted over large geographical
areas, where there is greater opportunity for escape.
Additionally, because there can be considerable
difference in invasion potential between different varieties
of the same species,305 it is critical that WRAs be
used for each individual cultivar under consideration,
not just each species. The sterile Illinois clone of giant
miscanthus, for instance, is likely to have a much lower
WRA score than PowerCaneTM giant miscanthus, which
has viable seeds.
Finally, ecological risk assessments for bioenergy must
address potential impacts of climate change, both
near-term and long-term. So-called “climate niche”
analysis is already commonly used by farmers and
horticultural experts to determine regions of agronomic
suitability (i.e., the ability to thrive in the particular climatic
conditions and therefore require minimal additional
inputs such as irrigation), as well as to identify regions
climatically suitable to a potential invasion.306,307 Such
studies will continue to be important for identifying
potential suitable areas as well as potential invasion
risks from bioenergy crops. In particular, species with a
broad range of climatic tolerance (a large climate niche)
often are considered among the best candidates for
bioenergy feedstocks, a factor that also enhances their
invasion risk. However, while such studies typically look
at historical/current climatic conditions to determine
suitability, they also must include projected changes in
climatic variables due to climate change. It is no longer
enough to say that because climatic conditions outside
of areas being considered for bioenergy crop cultivation
are unfavorable for the species, the risk of escape and
invasion is necessarily low.
Giant reed (Arundo donax), which is currently being cultivated for
bioenergy in some states, has been ranked as a likely invasive
species on at least 3 published weed risk assessments. Credit:
James H. Miller, USDA Forest Service, Bugwood.org.
33
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
6
Conclusions &
Recommendations
G
iven the enormous problems we face from
our continued reliance on fossil fuels to meet
our energy needs, finding meaningful alternative
energy sources is an important national priority. Energy
from biomass resources is likely to be a significant part of
America’s energy portfolio in the decades to come.
As this report shows, however, the use of non-native
and genetically modified native species as bioenergy
feedstocks can pose significant risks to native
ecosystems. The six case studies highlighted in this
report demonstrate that, despite the known invasiveness
and harm of many non-native feedstock plants for
bioenergy, these plants are nonetheless actively being
promoted and used for bioenergy production. If we
continue to implement bioenergy feedstock programs
without sufficient consideration of the potential ecological
and long-term economic costs, it will be only a matter
of time until great damage occurs, either ecologically,
economically, or both.
Other than some recent initiatives to improve
coordination, such as the establishment of the
National Invasive Species Council (NISC),308 the federal
government’s regulation of invasive plant species has
been reactive, incremental, piecemeal, and focused
primarily on protecting agricultural productivity. Its
ineffectiveness is apparent with the numerous invasive
species, including kudzu, common reed, and purple
loosestrife that are causing widespread environmental
and economic harm across the United States. Current
laws and regulations are entirely insufficient to adequately
prevent the establishment of new invasives, and to
control those already causing problems. Exacerbating
the inadequacy of existing programs to prevent
invasive species, federal agencies such as USDA face
a conflict of interest when they not only promote and
support agricultural commodity production, including
for bioenergy, but also have the responsibility for
enforcement of noxious and invasive species statutes.
Miscanthus growing in the shadow of the Washington Monument.
Credit: Marilyn Jordan, TNC.
If we continue to implement bioenergy
feedstock programs without sufficient
consideration of the potential ecological
and long-term economic costs, it will
be only a matter of time until great
damage occurs, either ecologically,
economically, or both.
These challenges are great, but they do not mean that
bioenergy development should not go forward; rather,
we must ensure that appropriate precautions are taken
to develop and use safe bioenergy feedstocks that can
help maintain and restore, rather than threaten, native
habitats. Efforts are underway to identify some key
actions that our nation can take to address the bioenergy
challenge without exacerbating the invasive species
problem. The federal Invasive Species Advisory Council
(ISAC) has recommended nine priority actions to the
NISC that would help ensure that the United States is
able to meet its commitments to expand bioenergy while
at the same time ensure that our important efforts to fight
invasive species are upheld (See Box 4).309
Box 4. The Invasive Species Advisory
Council Recommends the Following
Actions to Address the Invasive
Potential of Biofuels
1. Review/Strengthen Existing Authorities.
2. Reduce Escape Risks.
3. Determine Most Appropriate Areas for Cultivation.
4. Identify Plant Traits that Contribute to or Avoid
Invasiveness.
5. Prevent Dispersal.
6. Establish Eradication Protocols for Rotational
Systems or Abandoned Populations.
7. Develop and Implement Early Detection and
Rapid Response.
8. Minimize Harvest Disturbance.
9. Engage Stakeholders.
35
Similarly, the International Union for Conservation of
Nature (IUCN) has developed a set of recommendations
on reducing the risk of invasion from bioenergy
feedstocks from an international perspective (See
Box 5).310
Building on these recommendations from ISAC and
IUCN, we emphasize several key actions that we believe
must be taken in order to avoid the risk that continued
bioenergy development in the United States will also fuel
a growing invasive species catastrophe. Because the
ecological and economic costs of invasions are so high,
we believe that a precautionary approach is warranted.
1. Future bioenergy development should
encourage ecological restoration and improve
wildlife habitat through the use of ecologically
beneficial biomass feedstocks such as waste
materials and sustainably collected native
plants and forest residues.
The use of native grasses and other plants for bioenergy
production offers a promising opportunity to support our
growing energy needs while at the same time providing
important habitat for a range of fish and wildlife species. To
maximize benefits to wildlife, research and development
of feedstocks from native grasses should emphasize
mixtures of grass species interspersed with forbs and
shrubs. Once established, mixtures of native prairie
grasses and forbs can enhance overall biomass yields,
particularly on areas with degraded soils. Specifically,
research has shown that high diversity plots were found to
be up to 238 percent more productive than monoculture
plots, including plots of monoculture switchgrass that
had significantly reduced yields on degraded soils.311
Moreover, while the establishment of mixed prairie is
more complex than establishing a monoculture crop, the
benefits of establishing mixed native plantings may go
well beyond high yield. Together, these plant communities
can obviate the need for chemical inputs, support
numerous species of wildlife, and offer benefits for water
management, carbon sequestration, and other important
ecosystem services. For example, research shows that
biofuels derived from these low-input high diversity
mixtures of native grassland perennials can offer a carbon
negative option, as net ecosystem CO2 sequestration
is greater than the fossil CO2 released during the biofuel
production process.312
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
Box 5: IUCN’s Key Recommendations on Biofuels and Invasive Species
1. Follow a precautionary approach when choosing feedstocks.
Species should be chosen that minimize the risks to ecosystems
and livelihoods from invasion, either by the feedstock species, or
associated pests and diseases. Developers should also account for
the possible costs of an invasion when choosing species.
2. Work with stakeholders to build capacity. Existing regulations
are often robust enough in theory to reduce and contain risks of
invasions. The main barrier to their effective enforcement and success
comes from lack of capacity and understanding for the need to follow
best practices.
3. Comply with local, national, and regional regulations.
Regulations add an administrative and financial burden to developers,
but they exist to safeguard the environment, the livelihoods of local
communities, and the long-term financial sustainability of projects.
4. Develop and follow Environmental Management Plans. Develop
appropriate Environmental Management Plans (EMPs) that account
for the full range of risks and specify actions to manage the site
of production in such a way as to minimize the risk of escape and
invasion of surrounding areas, and deal effectively with any potential
or actual resulting invasion.
5. Extend planning, monitoring, and assessments beyond
the field. Consider developments within the wider context of the
landscapes and ecosystems in which they are situated. Risks may
extend beyond the site of production especially where adjacent areas
may be more susceptible to invasion and the dispersal mechanism
enables species to spread beyond the immediate site of a project.
Thus, adopting an ecosystem approach when planning developments
is preferable to only considering the risks posed by individual species.
Mixed prairie. Credit: Lynn Betts
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
36
Processing potentially invasive bioenergy feedstocks into pellets may reduce the risk of escape during transport.
Credit: Anthony DiChello/Bigstock.com.
Considerable attention has already been paid to
switchgrass, which is native to the central and eastern
United States. Within its native range, switchgrass
requires minimal management and can be harvested
for up to 10 years before replanting. Other grasses
under consideration include broomsedge bluestem
(Andropogon virginicus), little broomstem (Schizachyrium
scoparium), big bluestem , and indiangrass.313 It should
be noted that concerns have been raised over whether
native grasses, such as switchgrass, that have been
selectively bred to be high-yielding sources of biomass,
may pose a potential invasive risk to native prairie
stands. Research is currently underway in Minnesota
to better assess the invasive risk as well as the benefits
of selectively breeding switchgrass for bioenergy
production.314 To reduce the risk of invasion, efforts
should be made to avoid planting such species near
areas where virgin native grasslands still exist. Similarly,
as noted previously, there may be the potential for
species native in some areas to become invasive
outside of their endemic ranges - an important
consideration in determining where certain feedstocks
may or may not be appropriate.
Waste materials from various sources can also serve as
sustainable bioenergy feedstocks. These may include
wood and food wastes, such as wood from cleanly
separated municipal solid waste or construction and
demolition debris, forest industry residues, food product
wastes, sewage, and animal manures.315 In some
communities, for example, urban wood and yard wastes
are now being systematically collected for a wide variety
37
of renewable energy production systems. Residual
wood products from commercial forestry operations
are also being used for energy production, increasingly
using newer, cleaner combustion technologies.
Additionally, crop residues can offer another potentially
sustainable source of biomass production, provided
they are removed at sustainable rates that adequately
protect soil. In fact, the USDA and DOE estimate that
with 25 percent increases in yield, annual supplies of
crop residues could provide 244 million metric tons of
biomass – nearly enough to fulfill the amount necessary
to meet the requirements under the current Renewable
Fuel Standard.316
In addition, some scientists have suggested that residual
wood from management of forests affected by major
bark beetle infestations, wildfires, hurricanes, and other
natural disasters could be used as bioenergy resource.
For example, it is estimated that a one-time harvest
of dead trees associated with mountain pine beetle
outbreaks in areas of the Rocky Mountains in the United
States and Canada could supply fuel for biomass power
plants or other energy uses for 25 years, while at the
same time help reduce the associated risks of major
wildfires.317 It is important to consider that downed
trees and other forest debris left after disturbances
as well as many logging operations play an important
ecological role by protecting forest soils and providing
habitat for wildlife, benefits that would be reduced
by their removal.318 As with using control efforts for
currently-problematic invasive species (e.g., kudzu and
Chinese tallow) as a source of biomass energy, efforts
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
to capitalize on harvest of dead trees are necessarily
opportunistic and not necessarily sustainable over the
long term. Efforts to promote the use of currently-invasive
species and waste from disasters must first and foremost
be focused on ecosystem restoration.
2. Federal and state governments should
conduct coordinated efforts to prohibit or
restrict the use of known invasive species
as dedicated bioenergy feedstocks through
rigorous Weed Risk Assessment (WRA)
screening protocols.
To embrace precaution, we must first and foremost
take meaningful steps to ensure that species that are
already highly invasive or likely to become invasive (as
identified by a WRA) are prohibited for use in bioenergy
production. The potential ecological and economic risks
of a worsening invasive species problem are far too high
for us to ignore our past mistakes – especially where we
have an opportunity to be proactive. Indeed, prevention
of invasive species introduction is the cheapest and most
cost effective means of reducing the risks to both human
and natural communities.319 However, relatively few
resources are dedicated to preventing the introduction
of invasive species compared to expenditures for
management and eradication efforts after invasive
species have gained a foothold, at which point the
problem is far more expensive and difficult to address.320
A first step towards prohibiting the use of known
invasive species as dedicated bioenergy feedstocks is to
ensure that federal and state mandates and incentives
for bioenergy include consistent and well-coordinated
prohibitions on the use of invasive or potentially invasive
species. Through mandates, incentives, and agency
purchases, the federal government is currently putting
large amounts of money into bioenergy development.
The Department of Defense, for instance, recently
signed a contract to buy almost half of a million gallons
of biofuels for the U.S. Navy.321 With limited funds being
spent to promote second and third generation bioenergy
production, native and non-invasive species should be
prioritized. At the very least, federal funds should not
be used to promote or purchase bioenergy feedstocks,
including through funding research projects, until the
federal government has first demonstrated that the
feedstocks are safe by fully identifying and characterizing
the invasion risk for each feedstock prior to their use
through an environmental assessment process, which
includes a rigorous WRA. It is critical that each individual
cultivar, not just each species, is fully assessed for
its invasion potential. For those species with even a
moderate risk of invasiveness, we must require carefullycontrolled field trials, and establish mandatory mitigation
plans to reduce their risk of escape and invasion prior to
federal support of those species.
A first step towards prohibiting
the use of known invasive species
as dedicated bioenergy feedstocks
is to ensure that federal and
state mandates and incentives for
bioenergy include consistent and
well-coordinated prohibitions
on the use of invasive or
potentially invasive species.
Another way to prevent the use of risky bioenergy
feedstocks is by instituting federal and state permitting
requirements for the commercial use of non-native or
modified bioenergy species. Florida currently has a
permitting requirement for cultivation of non-native plants
(including GM plants) intended for biofuel production.322
According to their requirement, non-native biomass
plantings spanning more than two acres require a
permit from the Florida Department of Agriculture
and Consumer Services. While the permit process
disincentivizes the use of invasive species, it does not
necessarily restrict the cultivation of potentially invasive
species such as giant reed and napiergrass that not are
listed on Florida’s official noxious weed list. Permitting
programs can be tied to a WRA to evaluate potential
bioenergy feedstocks and restrict or regulate use of any
species with high probability of becoming invasive. As
a basic starting point, comprehensive WRAs should be
required for all varieties of potential bioenergy feedstocks
prior to their use to help identify the specific sources of
and reasons for potential risk of invasiveness.323 Species
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
38
with low risk of invasion could be permitted, and those
with even a moderate risk of invasion would have to meet
certain requirements, such as having monitoring and
eradication protocols, in place (See Recommendation #4).
The USDA recently released an updated weed screening
tool to identify invasive potential.324 While WRAs alone
may not be enough to fully and accurately assess
risk, and the screening tools must be continuously
be improved upon as our understanding of invasive
risks deepens, the WRA offers a good place for
agencies to start.
3. State and federal governments should
implement rigorous monitoring, early
detection, and rapid response protocols,
paid for through insurance bonding or other
financial mechanisms.
All too often, the cost of controlling an invasion by
a non-native species is borne by state and federal
governments. In California, for instance, more than
$70 million dollars have been spent over the past
15 years to control giant reed; invasion by the plant
has caused extensive damage to ecosystems and
human infrastructure in many of the state’s coastal
watersheds.325 Putting resources up front into
monitoring, early detection, and rapid response can save
money in the long-term. Both state and federal agencies
have established so-called Early Detection-Rapid
Response (EDRR) programs to provide an important
early line of defense against invasive species, before they
cause potentially irreparable harm to natural systems.326
Volunteers cleaning up invasive seaweed in Hawaii.
Credit: NOAA.
39
However, the burden of developing such actions should
not fall exclusively on the government and taxpayers.
Companies who grow potentially invasive bioenergy
feedstocks should be required to pay up-front costs
for control of the specific species they are growing
into a state account. These funds should be sufficient
to cover costs associated with containment, control,
management, and subsequent restoration efforts.
Those growing varieties that have higher risk according
to a WRA would pay higher fees than those scoring
lower risk. The state of Florida currently has such a
bonding program for bioenergy feedstocks that is
tied to its permitting program. The proceeds of the
bonding program go to fund eradication efforts of
invasive bioenergy crops. Bonding requirements can be
set up to include rigorous monitoring, detection, and
eradication protocols. Bonding requirements are currently
used in a variety of commercial operations including
hazardous waste treatment facilities, mining, and oilcarrying vessels.327
4. Feedstock producers should adopt best
management plans for monitoring and
mitigation to reduce the risk of invasion.
Because the full risk of invasion from biomass
feedstocks is often unknown, having a clear plan for
monitoring and remediation is critical, even for projects
using species with a low risk of invasion. Before any
feedstock becomes commercialized, companies that
grow potentially invasive bioenergy feedstocks should
be required to establish management plans that
embrace best practices for establishing, harvesting,
transporting, and storing feedstocks to reduce the risks
of invasion.328 Best management practices may include
timing harvests to minimize spread of seeds, maintaining
clean equipment, using closed transportation systems to
transfer feedstocks to production facilities, and putting
an eradication plan into place before production.329
For example, studies suggest that, with advances
in processing equipment, potentially invasive plant
feedstocks can be processed into useable forms such
as pellets where they are harvested, before they are
transported to the energy production facilities.330 Such
plans should also include avoidance and monitoring
for pests and pathogens that might spread from
cultivation sites and production facilities, both to protect
the bioenergy crop and other species that might be
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
impacted. Frequent monitoring of nearby fields and
roadways during the duration of the project and beyond
also should be a key component of any management
plan. In addition, bioenergy developers should be
required to regularly monitor their processes, from
cultivation and harvest to delivery and production, and
they must develop comprehensive contingency plans
that establish specific actions in the event of escape.331
Additionally, there are a number of voluntary certification
programs for sustainable biomass feedstocks that
currently exist or are being established, including the
Roundtable on Sustainable Biofuels,332 the Council for
Sustainable Biomass Production,333 and the Forest
Stewardship Council.334 Many of these certification
processes include carefully considered guidelines that
can help companies in feedstock selection, mitigation
and monitoring of potentially invasive biomass species.
5. The federal government should assign
liability to feedstock producers for damages
from and remediation of invasions by
feedstock varieties that they develop.
As mentioned above, once an invasive species spreads
into native ecosystems, the costs for eradication,
monitoring, and ecosystem restoration are often borne
by the state or federal government. There is currently
minimal incentive for individual landowners to control
the spread of weeds from an intentional planting or
introduction onto an adjacent landowner’s property, with
civil liability for the spread of weeds onto an adjacent
landowner’s property varying widely across states.
Accordingly, there is minimal incentive for bioenergy
producers to prevent the spread of invasive species. As
the pace of research and experimentation with nonnative and GM crops grown for bioenergy continues
to accelerate, it is critical that companies be held
accountable for the unintended consequences should
the feedstocks become invasive and spread. Assigning
liability for damages and remediation will incentivize
those companies to take precautionary measures to
reduce the risk of invasion – those producers who have
in good faith implemented best management practices
(see recommendation #4), including choosing low-risk
feedstocks, would not then be held liable. This idea of
a “polluter pays” principle for bioenergy feedstocks has
been recommended by IUCN, who states that “This will
help to clarify where responsibility lies for covering any
costs related to an invasion and encourage the adoption
of best practices to protect economic investments in
biofuels in the region.”335
6. Governments and businesses should
better account for the economic risks
associated with invasiveness of feedstocks
when assessing relevant costs and benefits
of potential bioenergy projects.
In decisions concerning the cultivation of non-native
species, the benefits of the species’ use must be
weighed against the potential ecological and economic
risks that may arise should the species become invasive.
In fact, while the 1999 Executive Order 13112 was
established to help protect the nation against actions that
cause or contribute to the introduction of harmful invasive
species, exceptions are granted provided that “the
benefits of such actions clearly outweigh the potential
harm.”336 In addition to identifying the ecological risks of
alternative bioenergy feedstocks, there is a critical need
to improve our understanding and consideration of the
potential economic risks associated with species that
have or may become invasive. The particular challenge
here is that, while identifying the economic benefits of
bioenergy is relatively straightforward, it is much more
difficult to compute the economic costs associated with
the ecological impacts of invasive species, especially
since many of the costs will be realized over the longterm.337,338 Without truly acknowledging the full potential
costs of invasions, decisions will likely more often than
not skew in favor of the economic gains from bioenergy.
Certainly the economic, social, and ecological costs
associated with climate change, global security, and
other major problems associated with fossil fuels that are
the impetus for bioenergy development are by no means
inconsequential. However, as Low, Booth, and Sheppard
(2011) argue, the “[p]romotion of biofuels as solution
to urgent global problems encourages trivialization of
weed problems.” What we need are meaningful policies
and programs that help promote a healthy, sustainable
bioenergy economy, while ensuring that our important
ecological values – which are often undervalued in the
marketplace – are protected.339
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
40
Concluding Thoughts
Native grasses not only reduce the risk of invasion, but they also
provide habitat for species such as this wild turkey. Credit: NRCS.
As this report has shown, the rapid expansion of
bioenergy production in the United States has generated
considerable interest in the use of non-native and
genetically modified biomass feedstocks that have the
potential to become ecologically-damaging invasives.
Should these species escape and become established
in nearby natural areas, the results could be costly and
devastating for native ecosystems. Despite this, few
safeguards exist in law to prevent the spread of invasive
species through bioenergy cultivation, and current risk
assessment methodologies alone may not be sufficient.
Policy makers, federal and state agencies, landowners,
feedstock producers, and the public all need to become
more aware of the potential for bioenergy feedstocks to
become invasive. As we move towards a clean energy
future, we must do so cautiously and responsibly.
Invasive species can wreak havoc on ecosystems and
economies; as we try to address the problem of
global climate change, we must avoid worsening the
invasive species problem. With foresight and careful
screening, we have important opportunities to minimize
and, where possible, prevent negative impacts of
biomass feedstocks on functioning ecosystems. By
implementing common-sense policies based first
and foremost on precaution, we can significantly
reduce the risk of invasion and help ensure a truly
sustainable bioenergy industry.
As we move towards a clean energy future, we must do so cautiously and
responsibly. Invasive species can wreak havoc on ecosystems and economies; as
we try to address the problem of global climate change, we must avoid worsening
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51
Growing Risk: Addressing the Invasive Potential of Bioenergy Feedstocks
A mixture of native grasses and forbs, which can support bioenergy production as well as provide important habitat for a range of
fish and wildlife species. Credit: Lynn Betts, NRCS.
W
e now have an opportunity to prevent irreparable harm by heeding
sensible precautions in order to avoid the risk that continued bioenergy
development in the United States will fuel a growing invasive species catastrophe.
With foresight and careful screening, we can minimize and, where possible, prevent
negative impacts of biomass feedstocks on functioning ecosystems. Bioenergy can
be an important part of a sustainable energy future, but only if it is produced in a
way that safeguards native habitats and minimizes the risk of invasion.
National Wildlife
Federation
National Advocacy Center
901 E St. NW, Suite 400
Washington, DC 20004
www.nwf.org