Fall
Seasonal Changes of Nutrient
Concentration in Rocky Mountain
National Park Soils
Keywords: Soil nutrients, Rocky Mountain National Park, Permafrost, Climate change, Tundra,
Forest
Abstract:
Supply an abstract of up to 200 words. An abstract is a concise summary of the whole paper, not
just the conclusions, and is understandable without reference to the rest of the paper. It should
contain no citation to other published work.
Sarah Heller
Mike Kozub
Judson Zevin
Sam Rooney
Cassandra Shenefelt
11
Table of Contents
Introduction .................................................................................................................................................. 3
Literature Review .......................................................................................................................................... 4
Objectives ..................................................................................................................................................... 7
Study Area ..................................................................................................................................................... 7
Methods ........................................................................................................................................................ 9
Discussion of Soil Nutrients ........................................................................................................................ 14
CO2 .......................................................................................................................................................... 14
Nitrates NO3 and Nitrites NO2 ................................................................................................................. 14
Ammonia and soils .................................................................................................................................. 15
Potassium ................................................................................................................................................ 16
Calcium.................................................................................................................................................... 16
Phosphate ............................................................................................................................................... 17
Conclusions ................................................................................................................................................. 18
References .................................................................................................................................................. 20
Figure 1: Field Sites in Rocky Mountain National Park ................................................................................. 9
Figure 2: Vernier Probe testing in the field................................................................................................. 10
Figure 3: Carbon dioxide field testing ......................................................................................................... 11
Figure 4: LaMott SmartSoil Testing Kit........................................................................................................ 11
Introduction
Rocky Mountain National Park (RMNP) in Colorado is a 265,828.41 acres national park
managed by the National Park Service. The park contains 60 mountain peaks over 12,000 feet
in elevation with glacier cut cirques and valleys. Rocky Mountain National park includes a wide
variety of ecosystems from alpine tundra, coniferous sub alpine forest, to mountain meadows.
Wildlife and outdoor recreational activities make Rocky Mountain National Park a very popular
tourist attraction. The expansive environment also makes the park a living outdoor laboratory
for research and scientific observation.
A top priority of the National Parks Service management is to preserve the native soils
and natural soil genesis from extensive human impact. Soil is defined as the unconsolidated
portion of the earth’s crust modified through physical, chemical and biotic processes into a
medium capable of supporting plant growth. “Soils are not static, but are in a dynamic
equilibrium with the surrounding environment” (NPS, 2011). Rocky Mountain National Park is
located 50 miles outside of the Denver metropolitan area. Previous studies have shown that
due to its close proximity to the city, wind-blown aeolian dust and changing levels of nitrogen
deposition are altering terrestrial ecosystems (NPS, 2011).
Soils are considered the second largest reservoir of carbon behind the oceans, (Chapin
et al. 2006) which makes them an important factor to consider in global climate change.
Permafrost soils have traditionally served as carbon sinks making northern latitude and
permafrost soils keystone global carbon reservoirs. Permafrost has recently come into view as a
new research platform due to the rapid melting that has been happening, “Permafrost is
defined as subsurface earth materials that remain below 0oC for two consecutive years,”
(Bioscience, 2008). Permafrost soils are less than 20% of global soil area and found mostly in
the Arctic regions and mountains as far south as the subtropics in the Northern Hemisphere
(Bioscience, 2008), but store 50% of below ground carbon. Increasing nitrogen levels combining
with increased temperatures threaten to uncap this frozen carbon sink. During the last glacial
maximum carbon permafrost may have been a key contributor of changes in atmospheric CO 2
(Science, 2006), this historic evidence could show that permafrost melt may become a key
contributor to an increase in global CO2 levels in the atmosphere. (Alaska Tundra, Natali)
The levels of Nitrate, Nitrite, Ammonia, Carbon Dioxide, and other soil nutrients are
important factors that measure fluctuations in the high alpine ecosystem. Soil nutrients can
change over time and can be influenced by climate, location, and geomorphology. The
research processes include the comparison of nutrient content of three alpine sites in Rocky
Mountain National Park. We will be calculating the changes in nutrient levels over five months,
June through September, in search of a significant correlation. Tree line patterns, permafrost
melting, and wind-blown sediment and their effects on nutrient levels are taken into
consideration in the data. The goal of this project is to examine the changes in nutrient levels
of the soil in the alpine tundra and coniferous forest located in Rocky Mountain National Park.
Literature Review
“Relative impacts of disturbance and temperature: persistent changes in microenvironment
and vegetation in retrogressive thaw slumps.”
This is a study about the effect of climate changes on permafrost degradation and the
effect the changing soils have on vegetation. The study found that warming permafrost can
change microclimate and expose areas of ion-rich minerals in the soils, consequently, the
response of vegetation to warming air temperatures may differ significantly from disturbed to
undisturbed tundra. The results of the study showed increased nutrient availability, soil pH,
snow pack, ground temperatures, and active layer thickness in disturbed terrain and suggest
that these variables are important drivers of plant community structure.
“Soil nutrient losses in an altered ecosystem are associated with native ungulate grazing.”
This study followed large grazing animals in Rocky Mountain National Park and found
that in the grazing areas soil nutrients were lower than other soils around the park. Samples
were taken in 1998 and 2010 to compare the effects of grazing animals over time. “Soil carbon
(C) concentrations were 25% lower in grazed areas than in exclosures; soil nitrogen (N)
concentrations were 23% lower. From 1998 to 2010, the mean percentage change for soil C and
N concentrations was +14% and +27%, respectively, in exclosures and -22% and -24%,
respectively, in grazed sites.” The most significant results showed that grazing in Rocky
Mountain National Park was associated with increased soil bulk density as well as decreased
soil moisture and concentrations of soil C and N.
“Regional and Local Patterns of Soil Nutrients at Rocky Mountain Treelines”
This study evaluated soil nutrient levels at eleven sites with abrupt transitions from
subalpine forest to alpine tundra in the Front Range of Colorado. Six sites were west of the
Continental Divide and five were east of the Divide. These sites were picked because soils
across the treeline should vary because of both biological differences of coniferous subalpine
forest and the herbaceous alpine tundra in Colorado. Nitrogen saturation is a growing concern
in high elevation ecosystems and treeline is predicted to be a deposition ‘hotspot.’ This is a
prediction based off the occasional east to west winds that bring the polluted air produced
from the agricultural and urban areas east of the Front Range upslope to the relatively pristine
high elevation ecosystems. The soil nutrients of this study did vary within the individual forest
and tundra sites but minimal effects on both sides of these abrupt treelines. The observed soil
patterns of this study suggest that acid deposition can be amplified by processes such as dust
deposition.
The unique setting of alpine treeline suggests the tree-wind interactions can predict
patterns in soil properties throughout forest and tundra sites. Unequal snow distribution based
on these interactions below the treeline is the most visual example of this effect, and a less
obvious effect is the difference in soil properties throughout the vegetation transition
associated with the presence of trees. In the front range of Colorado (Rocky Mountain National
Park), climate has been suggested as the dominant control on the shape and location of
treeline, contrasting with Glacier National Park where geomorphology and lithology are
stronger controls on the treelines.
This study observed that N and Ca in the treeline soils were higher on the east of the
divide, which is consistent with the predicted patterns. This provides support for the prediction
that the treeline is an accumulation zone, which adds to the growing body of evidence that
nitrogen deposition is altering ecosystem properties east of the CD.
“Summary of Effects of experimental warming of air, soil, and permafrost on carbon balance
in Alaskan Tundra”
Plots of land in the Alaska Tundra were warmed and cooled to gain perspective on the
effects of CO2 released from permafrost on the surrounding environment. The study found that
CO2 was lost from the soil to the atmosphere as the ground warmed. The highest increase was
in summer warming, the lowest was in the winter warming.
“Summary of Global Climate Changes and the Soil Cover”
Soil measurements in Siberia were analyzed to test the effects of climate change on
soils. The study found that an increase of CO2 levels in the air cause plant growth to rise, which
can cause lower levels in soil nutrients, as plant production increases need more soil nutrients.
This also depends on the plant life of the area- some areas that were tested in Siberia saw plant
and tree increases but not soil nutrient decreases because the soil could maintain an increase in
plant life.
Objectives

Comparison over time of soil nutrient levels

Are there significant increases of CO2 levels

Determine seasonal production of Nitrogen (in the form of Nitrite, Nitrate, and
Ammonia) and CO2 from high elevation soils

Relate collected soil nutrient data to seasonal climate change.
Study Area
The study area is located in Rocky Mountain National Park, which is northwest of Estes
Park, Colorado. Soil samples were taken at three sites along Trail Ridge Road. Trail Ridge Road
runs east/west through the entire park. The sites are located along a five mile stretch of Trail
Ridge Road on the eastern side of Rocky Mountain National Park. The three sites were used in
this study because they have different elevations and are in different environments. Sites 3 and
4 are located in the tundra above the tree line. Site 3 samples were taken in a location of
organic soils. The elevation of the site is 3676 m. The slope is 4°, meaning that the site is on a
relatively flat area. It has an aspect of 203, which means the site is facing southwest and gets a
good amount of sun. Site 4 samples were taken in a mineral soil. The elevation of this site is
3678 m. It is located on a slope that is 9°, so again, relatively flat. It has an aspect of 165, which
means it is facing southeast, and again, receives a good amount of sun. The forest site samples
were made in a plant rich organic soil and will be primarily used for comparison between the
tundra sites. The forest site has an elevation of 3218 m. It is on a bit of a hill with a slope of
24°. The aspect of the forest site is 27, which means it is facing northeast. It is not located on a
sun-facing slope and also has a lot of tree shading.
The sites are usually covered in snow during the fall and winter, then uncovered in the
spring and summer. Last year’s weather was unusual in that the tundra sites were covered in
more snow than usual, approximately 2 meters in June. The forest area, which because of the
tree shading, generally has snow cover for a longer part of the season, but all three sites were
covered in June and melted about the same time in July. When the last samples were taken in
September, there was no snow cover on any sites.
Figure 1: Field Sites in Rocky Mountain National Park. Basemap from USGS
Methods
The data collected for this paper is part of an ongoing study. The data was compiled
monthly from June 2011 to September 2011. Temperature and CO2 levels were collected by
data loggers previously placed on the three collection sites in 2008. Soil moisture was collected
using a Venier probe. At each site, we used a trenching shovel to take samples of soil near the
data loggers. About three one-gallon bags were filled with soil from each site. The samples
were then stored cold until chemical analysis was conducted. Chemical analysis included nitrite
(NO2-), nitrate (NO3-), calcium (Ca2+), phosphorous (P), ammonia (NH3+), and potassium (K).
Each nutrient was tested with the LaMottSmartSoil Testing Kit, using the kit’s guidelines for
extraction and measurement of each chemical. Using an extracting agent, each nutrient was
isolated and measured using the colorimeter to determine levels in parts per million. The data
was input into Microsoft Excel and graphs were made to aid in observing any seasonal trends.
Statistical analyses were then applied to make a mathematical correlation with the data.
Figure 2: Vernier Probe testing in the field. Photo by Samantha Rooney
Figure 3: Carbon dioxide field testing. Photo by Samantha Rooney
Figure 4: LaMottSmartSoil Testing Kit. Photo by Samantha Rooney
Results
6/10/2011
7/7/2011
8/17/2011
9/30/2011
Nitrate
Tundra (mineral)
Tundra (organic)
Forest
0
0.18
0.01
0.01
0.06
0.06
0.07
0.03
0.09
0.13
0.08
0.04
0.91
0.52
0.72
0.48
1.9
1.13
1.05
0.68
1.54
1.11
1.12
1.14
Ammonia
Tundra (mineral)
Tundra (organic)
Forest
Nitrite
Tundra (mineral)
Tundra (organic)
Forest
0.013
0
0
0.011
0.008
0
0.013
0
0.012
0.027
0.019
0.008
0.48
0.16
0.23
0.47
0.97
0.32
0.26
0.35
0.4
0.67
0.8
0.58
3.2
2.3
4.8
1.4
10.1
3.5
2.7
3.7
7.7
7.5
9.5
9.9
701.76
660.48
1279.68
619.2
1279.68
1279.68
949.44
619.2
1444.8
1816.32
2476.8
2972.2
750
1150
1340
850
1780
2680
920
1110
4100
1990
1900
2030
26
4
26
32
2
8
18
0.5
6
Phosphate
Tundra (mineral)
Tundra (organic)
Forest
Potassium
Tundra (mineral)
Tundra (organic)
Forest
Calcium
Tundra (mineral)
Tundra (organic)
Forest
CO2
Tundra (mineral)
Tundra (organic)
Forest
Soil Moisture
Tundra (mineral)
Tundra (organic)
Forest
Discussion of Soil Nutrients
CO2
In the past few decades the ‘greenhouse gases’ such as carbon dioxide CO2, methane
CH4 and nitrous oxide N2O have been increasing. CO2 may be the most important as it accounts
for 60% of global warming/climate change. Soil is an important sink for CO2 as it contributes
20% of the total CO2 in the atmosphere. Production and emissions of this gas is dependent on
factors such as pH, temperature, moisture, texture, and nitrogen content.
Studies have shown that there is a strong correlation between CO2 and temperature.
CO2 levels have been noted to be highest in midsummer. A concern with temperature is that
CO2 evolution from the soil may accelerate the depletion of soil carbon and soil fertility. It is
estimated that 1°C increase in temperature can lead to 10% loss of soil organic carbon in
regions of the world with annual mean temperature of 5°C, while regions with a mean
temperature of 30°C would still have a 3% loss.
Nitrates NO3 and Nitrites NO2
Nitrogen is an essential nutrient in soils that is used by vegetation for growth. The
nitrogen cycle is a natural process that removes plant-available nitrogen from soil and releases
it into the atmosphere. Increased nitrogen relates to increased permafrost melt and the release
of CO2 to the atmosphere. Nitrites (NO2) and Nitrites (NO3) are vulnerable to leaching and
denitrification in saturated soils. Leaching is defined as the removal of soluble material through
the percolation of water. Organic matter is typically removed from a soil horizon and soluble
metals or salts from a rock by leaching. Denitrification is an anaerobic process that is carried
out by denitrifying bacteria, which convert nitrate to di-nitrogen (N2) in the following sequence:
NO3-
NO2-
NO
N 2O
N 2.
(Harris, 2003)
Once converted to the gas form, N20 and N2, the nitrogen rapidly dissipates into the
atmosphere. This nitrogen is no longer available to support vegetative biological processes. In
addition, gaseous nitrogen forms are considered to be greenhouse gases that contribute to
global climate change. As permafrost and RMNP soils melt and become saturated the nitrogen
cycle will go into production releasing gaseous nitrogen into the atmosphere. (Harris, 2003)
Ammonia and soils
Ammonium is made up of nitrogen and hydrogen (NH4). Shortly after application, the
ammonium binds to soil or organic matter. Eventually it is converted to nitrate by bacteria in
the soil. In the conversion process from ammonia to nitrate, three hydrogen ions are released
into the soil solution. They are then free to react with other substances in the soil. Free
hydrogen is very active and is the "acid" in the soil. The H+ can react with lime in the soil
forming water and CO2 and be neutralized or it can be tied up on soil particles. (Vagts, 2005)
Potassium
Potassium in soil is very important to plant growth; potassium is a catalyst agent in
plants and helps to regulate plant processes such as photosynthesis and the maintenance of
water content. Potassium exists in three forms in soil, unavailable, water soluble, and
exchangeable.
Water soluble potassium is usually found in salts such as KCl (potassium chloride) and is
very soluble in water. Available potassium is usually applied as a fertilizer to the upper most
levels of the land and comes from decaying matter. The unavailable potassium is formed from
weathered minerals, and is usually held in clays such as vermiculite. Potassium is better
absorbed in warm, moist climates while cold climates can make the proteins almost
immoveable.
Calcium
Calcium in tundra soils plays a large role in the soil pH. If the soil does not have an
adequate amount of calcium the pH of the soil will be lower while a calcium rich soil has a much
higher pH. Calcium in soils has a direct effect on vegetation and the correlating biological
processes. The availability of plant nutrients is influenced by the amount of carbonates found
in the soil. Plants in the tundra use the calcium in soil for nitrate uptake and cell division. If soil
becomes too acidic the plants will suffer and calcium is needed to help balance the pH. In our
study we saw levels of calcium slightly higher than the optimum amount in tundra soil. In our
forest site the calcium was much higher than the steady tundra sites. This increase in calcium
can be expected due to the thicker vegetation in the forest, but also can be a result of calcium
from areas around RMNP transporting into the forest and settling in the soil. The forest site is
better at catching and retaining the calcium than the tundra sites which would explain the
higher amount of calcium in the forest soil. The tundra sites are also more likely to have run off
during melting and calcium can be lost in the runoff whereas in the forest the vegetation will
retain the calcium better.
Phosphate
Phosphorous in soils plays a large part in plant growth. Phosphorous can be found in
inorganic or organic compounds in soil. In solution form, the element phosphorous is mixed
with oxygen to create inorganic orthophosphate (phosphate). Inorganic phosphate is often
found in compounds with aluminum, iron, and calcium. This is the only form of phosphate that
plants take in as nutrients. Animals that eat the plants will absorb the phosphate as well. The
phosphate is then returned to the soil either as animal manure or from plant decay. This
returned phosphate is organic phosphate and it is not available for plant use until it goes
through a process called mineralization, where microorganisms break down organic
compounds. During the mineralization process, organic phosphate is slowly changed back into
inorganic phosphate.
Phosphate levels are more abundant in fine-grained soils and clay than in larger grained,
sandy soils. In the Tundra (mineral) site, levels in June are 0.48 ppm and then fall sharply to
0.16 ppm by July. The levels slowly rise to 0.47 ppm by the last measurements in September.
The Tundra (organic) site has similar results. In June, the site recorded 0.97 ppm and then
sharply drops to around 0.32 ppm by July. The levels continue to drop but at a slower rate to
0.26 ppm in August and then rise to 0.35 in September. The Forest levels recorded were 0.4 in
July, then rise to 0.67 in July. They rise even more to 0.8 ppm in August and then back down to
0.58 ppm in September.
Conclusions
Nitrate (NO3)and Nitrite (NO2) concentration in RMNP soils are shown to be consistently
low to nonexistent over the four month period of June to September 2011. Nitrate (NO3) levels
overall are at their highest for the three sites in July but drops for the months of August and
September to under 0.05ppm. This correlates to an increased moisture percentage of 17-33% in
the month of July. Overall the fluctuation of nitrite and nitrate seen in the charts is concluded
to be caused by natural seasonal changes. Melting permafrost is just the catalyst needed to
place the nitrogen cycle in motion.
Decreased ammonia in relation with increased nitrogen suggests an active nitrogen
cycle taking place in the study areas. The highest ammonia levels are found in June, decreasing
over the summer. Nitrogen levels appear to peak in July, then decrease and level off from
August to September. The data suggests that an active nitrogen cycle is taking place as
ammonia is converted to nitrogen. The nitrogen is then in turn converted to a gas that is
released into the atmosphere. Carbon Dioxide levels may also increase as Hydrogen ions are
available to acidify the soil and react with carbonates. However, more data is needed to verify
such a relationship in the study sites.
In the graph of potassium content there is no clear correlation for the levels. The forest
site seems to just increase, while the tundra mineral site peaks in August then drops off again.
The tundra organic site seems to just drop and slightly rise again in August. The best reason for
the correlation, or lack of, has to be related to the available plant matter located near the sites.
The sharp fall in phosphate levels in the tundra occur between June and July, when this
year’s snow was melting. The drop is probably due to runoff occurring during the spring snow
melt, because phosphate tends to be attracted to smaller soil particles that would be caught in
any water runoff. The levels rise as they are replaced during the warm seasons. The forest site
had surprising results, levels rose from spring to summer. It was expected to sharply fall as well
since the site had the steepest slope and was more likely to experience runoff. In all cases, the
falls and rises in levels are not huge, never rise or dropping more than 1 ppm, so it is more likely
that over time, the forest levels will probably meander between 0.4 and 0.8 ppm and with more
data, it will show that levels actually pretty consistent and do not rise or fall depending on the
season.
The calcium levels were higher than the optimum levels and ranged from 660 ppm to
1,816 ppm. The optimum calcium level in soil is between 400-1000 ppm (Soil and Applied
Calcium). The forest site was significantly higher in calcium than the mineral and organic sites.
The high amount of calcium in the soil helps the tundra soil balance the pH which promotes
healthier vegetation.
Overall, available soil nutrients vary with seasons, in that higher temperatures and soil
moisture can increase and decrease the nutrients available. Many factors can change the
nutrients besides temperature such as location, geomorphology, biology, and parent material.
The idea that permafrost melt will increase greenhouse gases is very likely but further research
needs to be done to create a thorough conclusion on whether this is a prominent feature and
process in Rocky Mountain National Park.
References
Binkley, Dan, and Tobah M. Gass. "Soil nutrient losses in an altered ecosystem are associated
with native ungulate grazing." Journal of Applied Ecology 48.4 (2011): 952+. Academic
OneFile.Web. 4 Nov. 2011.
Busman, Lowell, et al., “The Nature of Phosphorous in Soils.” University of Minnesota
Extension.Reviewed July 2009.
http://www.extension.umn.edu/distribution/cropsystems/DC6795.html
Espinoza, Leo, et al., “The Nitrogen and Phosphorous Cycle in Soils.” University of Arkansas
Division of Agriculture. http://www.uaex.edu/Other_Areas/publications/PDF/FSA2148.pdf
Gergel, Sarah E., et al., "Relative impacts of disturbance and temperature: persistent changes in
microenvironment and vegetation in retrogressive thaw slumps." Global Change Biology
15.7 (2009): 1664+. Academic OneFile.Web. 4 Nov. 2011.
Harrison, Ph.D., John Arthur "The Nitrogen Cycle: Of Microbes and Men," Visionlearning Vol.
EAS-2 (4), 2003. www.visionlearning.com/library/module_viewer.php?mid=98
Kudeyarov, V.N. et al., “Summary of Global Climate Changes and the Soil Cover Aurasian Soil.”
Science 2009 vol 42 No. 9 pp 953-966
Natali, et al., “Summary of Effects of experimental warming of air, soil, and permafrost on
carbon balance in Alaskan Tundra.” Global Change Biology 2011 p. 1397-1407
Vagts, Todd. "Ammonia Fertilizer and Soil PH." Nitrogen Fertilizers and Soil PH. Iowa State
University Extension and Outreach, 26 Jan. 2005. Web. 10 Nov. 2011.
www.extension.iastate.edu/nwcrops/fertilizer_and_soil_ph.htm