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www.FarmProgress.com April 2013
The Farmer-Stockman
SILVERLEAF NIGHTSHADE
PHOTO: TEXAS A&M AGRILIFE EXTENSION
Natural Resources
Plant succession: a prerequisite
for proper habitat management
WILDLIFE
W
BY DESIGN
B
By DR. DALE ROLLINS
B
P
LANT ecologists define “succession”
as the “orderly, predictable process
of change in plant communities over
time.” The ability to advance, or retard,
succession (depending upon one’s desired
plant community) is the single most important tool of the wildlife habitat manager.
Think of plant succession as a pendulum swinging back and forth. As it
reaches its left-most point, think of that
point as bare soil. A swing to the far right
would be at the “climax” plant community
(e.g., a pristine plant community for that
particular site). Depending on where we’re
at in the pendulum’s swing, we can expect
plant communities consisting of weedy annuals to perennial grasses and legumes.
Ecologists break down the span of the
pendulum’s swing into “seral stages.”
Early succession, also referred to as a
low-seral stage, characterizes a site that
would consist mainly of annual forbs and
grasses. Annual sunflower, doveweed and
sourgrass are good examples of early succession. You may know such species as de-
Key Points
■ Plant succession is big tool for wildlife
habitat.
■ Certain rules apply to plant succession
processes.
■ Being able to read the rangescape is a
fundamental ability.
sirable seed producers for quail and dove.
As the plant pendulum continues to
swing right, the annual plant community
begins to include some perennial grasses
(threeawns, silver bluestem) and forbs
(western ragweed, silverleaf nightshade).
As it continues to swing to the ecological
right, perennial grasses like sideoats grama
and little bluestem may share a site with
Englemann’s daisy and bush sunflower. The
time span for this pendulum swing would
be 20 to 40 years, depending on the site.
Management impact
Management options retarding succession
include those that provide ground disturbance (plowing, dozing, livestock grazing
and drought). Practices that might fastforward succession include fertilization
or reseeding. Practices like burning and
grazing may advance succession at some
times of the year, such as early spring, but
retard succession at another time in the
community’s growth, such as late summer.
The operative word in this discussion
about succession is “predictable.” Disturb
sandy soil during January, and expect a
flush of doveweed and sunflower. On a
clay loam site, a disturbance may foster
snow-on-the mountain or buffalobur. Graze
down a stand of sideoats and silver bluestem in the fall, and increase the amount of
western ragweed the next spring. Take it to
the bank. For a webisode on succession as
it relates to quail, see www.youtube.com/
watch?v=c2WsEGY2Ctk.
Playing by the rules
I ascribe certain rules to the successional
processes. First is a commonly accepted
principle that nature abhors a vacuum. In
ecological parlance, this means something
will grow to protect the soil surface. Bob
Steger of San Angelo used to rephrase this
maxim as, “Mother Nature is not a nudist.”
I define “Rollins’ Rules of Succession”
as a tandem: Know your plants and know
how to manipulate them. Think about it.
If I want a sward of bluestem and sideoats
for my cows, then the wrenches in my ecological toolbox include primarily grazing
management and prescribed burning. But
for bobwhites, I want a patchwork assemblage of early successional forbs (broom-
weed), nesting cover (little bluestem) and
low brush about a softball throw apart.
Reading is fundamental in this relationship. The ability to read one’s rangescape
affords the manager the opportunity to
decipher some pretty interesting sagas
on the Back 40 — sagas of give and take,
and push and shove. Given that the
“words” therein are plants, ask yourself
how good is your vocabulary. Are you a
silver-tongued orator (“eloquent”) or a
Neanderthal (“ugh”)?
If you’ve ever attended a field day or
range tour where I’m speaking, likely I exhorted you to get on a “name-calling” basis
with your plants. If you can’t name your
property’s top five grasses for cows, the
top five brose plants for deer, and the top
five seed producers for bobwhites, your
homework is past due. Get studying!
The tools of the succession manager
aren’t new. Aldo Leopold summarized them
in 1933 as “the axe, cow, plow and fire.” In
our area, the “axe” takes the form of brush
management; the “cow” indicates grazing
management; the “plow” might be a tandem
disk or a farm program; and “fire” (prescribed burning) rounds out our arsenal.
Are you a handyman with these various
tools?
Rollins is Texas A&M AgriLife Extension
wildlife specialist, San Angelo.
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