Download Yearly and Seasonal Ground Temperature Variations

Yearly and Seasonal Ground
Temperature Variations in Rocky
Mountain National Park, Colorado
Heather Burnett, Kristen Sanders, Nic Sears, Zachary Trabold
Environmental Field Studies, Fall 2010, Metropolitan State College of Denver
Abstract: Climate change continues to be a growing concern in the World. Alpine landscapes, such as
the tundra biome of Rocky Mountain National Park in Colorado, have increasingly been looked to as
indicators of climate change and its implications. From thirty temperature data loggers along Trail Ridge
Road within the park, five were chosen for further investigation. Data loggers gathered temperature at
two hour intervals over a two year period. Soil properties, aspect, and elevation were all recorded for
analysis and correlation. We used two sample t-tests assuming unequal variance to establish statistical
proof of warming or cooling. Yearly averages were also employed for graphs giving a simpler view of
the results. Surface sensors for sites 3, 7, 17 and 25 showed temperature increases at their internal sensor
buried just 10 cm below the surface, while site 10 showed cooling. Ground temperature as measured by
the external sensor buried 30 to 85 cm exhibit predominately cooler temperatures for sites 3, 17, and 25,
but warming at sites 10 and 7. These illustrate ground’s resilience to change but, an overall increasing
temperature. Such studies are crucial in establishing ecosystem loss in response to climate change.
Keywords: Alpine Tundra, Permafrost, Climate Change, Rocky Mountain National Park, Ground
Temperature, Trail Ridge Road
Introduction
Global warming is of concern because even a seemingly minute change in global temperature as
low as 1° C can alter 10% of all ecosystems based on Global Climate Models (GCMs). Biome
distribution and species distribution are susceptible to 1°C to 2°C increases in global mean temperature
(Leemans & Eickhaut, 2004). Tundra biomes are particularly susceptible to temperature changes and
ecosystem disruption (Leemans & Eickhaut, 2004). Alpine systems and subarctic cold mountain
environments commonly contain temporarily frozen ground called the active layer and permafrost
(ground that remains frozen at 0°C or below for two or more consecutive years) (Kneisel, 2010). The
temperature of the ground at these locations is typically regulated by solar radiation, snow cover thickness
and duration, vegetation, as well as the organic layer and soil characteristics (Janke, 2005). With global
temperatures on the rise, these regulatory factors could be influenced and locations with near-surface
ground ice will experience extreme terrain degradation and substantial ecosystem impacts, including
possible carbon dioxide (CO2) and methane gas release (Kneisel, 2010; Kvenvolden & Lorenson, 1993;
Leemans & Eickhaut, 2004). This study focuses on the ground temperature changes in the active layer of
tundra in a section of Rocky Mountain National Park (RMNP) in Colorado. Determining if ground
temperature changes are occurring can help park officials and decision makers manage potential effects
and mitigate impacts (DOI et al., 2007). This information can then be applied to the Front Range of
Colorado.
Presently, there is a consensus amongst the scientific community that global warming is a reality
and that global climate change (GCC) is taking place and will continue (IPCC, 2007). The causes of
global warming include natural sources and events, but the main cause of concern is an increase in
greenhouse gases (GHGs) from anthropogenic sources (IPCC, 2007). Since the mid-nineteenth century
when the modern Industrial Revolution began, anthropogenic carbon dioxide in the atmosphere has
increased beyond pre-Industrial Revolution levels of 280ppm to 388.59ppm as of November of 2010
(Butler et al., 2008; Tans, 2010). The abundance of methane gas has more than doubled since the
Industrial Revolution to approximately 1800 ppb (NOAA, 2008). While less abundant than CO2 and
water vapor, methane is 25 times more potent as a GHG than CO2 (NOAA, 2008; Wuebbles & Hayhoe,
2002). Permafrost is a large store of CO2 and methane, which, when warmed, has the potential to release a
tremendous amount of these GHGs into the atmosphere adding to the greenhouse effect and thus causing
an additional rise in temperatures (Kvenvolden & Lorenson, 1993; NOAA, 2008; Wuebbles & Hayhoe,
2002).
Snow cover thickness and duration, vegetation, as well as the organic layer and soil
characteristics are likely to be influenced by warming temperatures due to GCC. As temperatures warm,
snow cover duration will decrease, impacting the hydrologic cycle due to decreased water retention for
spring runoff (Kneisel, 2010; Leemans & Eickhaut, 2004; DOI et al., 2007). Warming temperatures will
likely cause the shrinking of species populations and habitats for species such as the lynx and pika, which
depend on the snow cover duration and thickness for their survival (DOI et al., 2007). The tundra biome
would decrease in size as mountain biomes shift up in elevation due warmer temperatures at lower
elevations (Leemans & Eickhaut, 2004). Thawing of permafrost and the active layer will lead to a change
in soil moisture content, decreased soil cohesion, increased soil erosion, and a change in soil microbial
activity (Zhao-ping et al., 2010). Soil slumping from a lack of cohesion of soil due to decreased ice would
disturb plant life on the tundra (Zhao-ping, 2010). Increasing temperatures and changing soil chemistry
would also corrupt plant life (Leemans & Eickhaut, 2004; Zhao-ping, 2010).
This study shows how ground temperatures of the tundra in a section of RMNP have changed
overall from year to year and seasonally during a period of two years from the summer of 2008 to the
summer of 2010 to help further the understanding of the changing conditions at the park for park officials
and decision makers. This study can help direct future research and guide park authorities in mitigation
and management strategies.
Literature Review
The impending consequences of climate change on alpine soils are evaluated by dozens of
scientists around the world. Many approaches to the subject have created a vast array of information
varying from the impact of snow cover on thermal heat exchange to the effects of elevation and aspect on
seasonal temperature variance. Permafrost and frozen soils are of significance to the subject of climate
change as they serve as carbon sinks and are essential to fragile alpine vegetation (Borken, & Matzner,
2007). In one of the most relevant articles found during research on this topic, researchers at the
University of Bonn, Department of Geography in Germany, analyzed soil temperatures from the surface
to a depth of 15 cm, including variations caused by microspatial differences, and the effects of altitudinal
forces (Loffler, Pape, & Wundram, 2010).
The results are presented in a series of isocline diagrams depicting temperature gradients between
each site comparing low and middle alpine areas in Norway “This enabled us to quantify the significance
of soil temperature gradients across vertical soil profiles, topography, and altitude in order to facilitate
future microclimate extrapolation and modeling in high mountain landscapes” (Loffler, Pape, &
Wundram, 2010). This research is valuable to this study as the methods are similar measureing
temperatures at comparable depths and conditions. The instruments used to collect the data are alike,
although the German researchers have access to a greater range of data collection such as barometric
pressure, solar radiation, humidity and wind direction. According to the results three specific factors are
responsible for temperature variation: the thickness and duration of snow cover, topography, and soil
composition (including proximity to bedrock). They concluded “that mean temperature values are
unsuitable for representing the altitudinal changes of high mountain climate” (Loffler, Pape, &
Wundram, 2010). It was found that with so many factors contributing to temperature variance it is
difficult to correlate it with climate change. In a similar study the effects of climate change of permafrost
are evaluated.
The loss of permafrost around the world’s tundra regions is often referred to as an indicator of
climate change, due to the fact that it is maintained by climates that have prevailed over hundreds, to
thousands of years (Pewe, 1975) The park contains several permafrost zones where the ground is more
likely in certain areas to maintain constant freezing and areas that fluctuate more greatly during seasonal
temperature changes (Janke, 2005). Referred to as the continuous and discontinuous, enduring permafrost
is independent of ecosystem structure and less susceptible to changing conditions, while soils frozen for
merely several years at a time are believed to fluctuate with weather changes (Shur & Jorgenson, 2007).
Research conducted by the University of Alaska Fairbanks produced five levels of permafrost degradation
have been classified based upon the interaction of climatic and ecological processes: climate driven,
climate-driven ecosystem modified, climate-driven ecosystem protected, ecosystem-driven, and
ecosystem-protected (Shur & Jorgenson, 2007). For example ecosystem protected permafrost will be
maintained if factors such as vegetation and hydrology if they remain at a constant.
The majority of frozen ground in the United States is found mostly in Alaska, but has been
located in the higher altitudes of the Rocky Mountains in Colorado above 3,000 m (Janke, 2009). This
study is a continuance of the work compiled by Dr. Jason Janke, in RMNP evaluating the fluctuations of
soil temperature along Trail Ridge Road. The relevance of two ongoing studies at the Long Term
Ecological Research Site (LTER) Niwot Ridge and the Critical Zone Observatory Site (CZO) Green
Lakes in Colorado is discussed by German ecologists as possible predictors of climate change.
The study sites provide a compellation of past and present data that are used to create future
predictions. “At some locations, we find large differences when compared to the older data and the
prognostic model. Sites formerly indicated as permafrost in the 1970’s shifted towards sites with annual
ice lenses today” (Leopold, Voelkel, Dethier, Williams, & Caine. 2010). Three methods are used to
collect the data: electric resistivity tomography (ERT), ground penetrating radar (GPR) and shallow
seismicrefraction (SSR). As with the RMNP study two boreholes were drilled at 3,500ft to record soil
temperature (Leopold, et al. 2010). The study found no evidence of permafrost at the selected sites on
Niwot ridge, although it had a calculated 63% probability. Permanently frozen ground was found near
Green Lake Valley at 3,600 M, where it was also reported to exist in 1974 (Leopold, et al. 2010). Due to
the huge variances found in the results it was concluded that the presence or absence of permafrost cannot
be definitively linked to global warming without further study.
Extensive research has been conducted in the Swiss Alps in regard to this subject, and may prove
to be a more definitive area due the recorded presence of permafrost and the long history of recorded data
in the region. Characteristics of frozen ground vary greatly depending upon hydrological conditions, snow
cover, solifluction, and surface or below ground textural character (Kniesel, 2010). During a warming
period permafrost is likely to disappear first from marginal areas with mean yearly temperatures near 0°C;
while terrain with the largest amount of near surface ground ice will be the most disturbed. According to
Kniesel the heterogeneous tendencies of high altitude subarctic environments are a challenge and
knowledge of the factors determining the presence or absence of permafrost specifically at the fringe of
these environments are the key to understanding climate change.
Alpine tundra environments in Abisco Sweden were monitored using geomorphologic mapping,
near surface temperature monitoring, and 2D near surface geophysics. The temperature measurements
collected in this study use different techniques than those taken in RMNP. Using a 3m thermistor probe
inserted through winter snowpack of at least 80cm, and into the ground surface, Bottom Temperature
Snow (BTS) measurements were recorded, as well as surface temperatures from data loggers. There are
three different probabilities used to determine the presence of permafrost using this method: (<-3°C)
permafrost probable, (-2°C to -3°C) possible, and (> -2°C) improbable (Kneisel, 2010). The results found
areas of probable and possible permafrost in areas of patterned ground, and improbable areas in lower
altitudes. The most promising sites, loggers 4and 5, found surface temperatures unfavorable to permafrost
conditions, yet the BTS readings were between -2.5°C and -3°C well within the probable zone (Kneisel,
2010). The variance in temperature may be due to the insolative effect of the snow and the cold
temperatures being emitted from the ground. Due to the fact that RMNP does not maintain a snowpack
deeper than 80 cm this method cannot be used.
A fifteen year study of the effects of permafrost degradation on vegetation in the Qinghai-Tibet
Plateau found that ground temperature fluctuation can profoundly affect alpine ecosystems. The complex
relationship between high altitude vegetation and permafrost were investigated by measuring the active
layer, thickness of frozen ground, and mean annual ground temperature. It was found that as the ground
thawed the active layer increased, the organic matter in the soil exponentially decreased, and the surface
became less compact and gravely (Wang, G., Li, Wu, & Wang. 2005). The results showed that over the
15 year period “the distribution area of alpine cold meadow decreased by 7.98% and alpine cold swamp
decreased by 28% under the permafrost environment degradation” (Wang, G. et al, 2005). It was
concluded that in the next fifty years theses alpine ecosystems will undergo serious dilapidation. This
research reveals the complex relationship between frozen soils and fragile vegetation, and how climate
change will greatly impact the world.
Objectives

Analyze soil temperature data at the surface and at depth from five study sites throughout Rocky
Mountain National Park to determine whether this region is experiencing climate change.

Determine whether temperatures are increasing, decreasing, or remaining constant during
individual seasons from 2008 – 2010.

Find if there is there an overall increase or decrease in soil temperature in the RMNP region from
the entire year by extrapolating our data from the five sites.

Determine if a difference is observed, is it statistically significant using a two sample t-test
assuming unequal variances at a 95 % confidence level.

Does the soil type and vegetation cover effect soil temperatures in an alpine region and what are
the effects, increased cooling or warming relative to surrounding sites with different
characteristics.

Which seasons and sites experienced the greatest change and how does this relate to
environmental variables of the region, such as aspect, altitude as well as soil type and vegetation
cover.

Where is the largest vertical temperature gradient located from the five study sites, and what year
did it occur. Does this relate to the soil or environmental characteristics of an individual site, or
the seasonal variability?
Study Area
The area of study is located in Rocky Mountain National Park (RMNP), which lies to the west of
Estes Park, CO. This study consists of five sensors recording surface and ground temperature data at
locations along an approximately 5 mile (8,047m) stretch of Trail Ridge Road within RMNP. Elevations
in this area range from approximately 3505m to 3740m. The area has a periglacial surface in a
predominantly tundra biome. Each site lies on a different aspect, with elevations within 160m of each
other, as seen in Table 1 (Janke, 2009).
The tundra area is too harsh to sustain trees, but a low carpet of assorted tundra plants covers the
area. Animals such as pika call the tundra their home living in the rock crevices and burrowing in the
snow during winter. While seen in many parts of the park, elk can often be seen above timber line grazing
on the tundra plants ( DOI et al., 2007). Maps of the study area are below in Figure 1.
Table1. Site Description, Elevation, and Aspect
Site
Descripti on
Elevation
Aspect
3
7
10
17
25
Earth Hummock
Tundra below rock outcrop
Solifluction
Between stone stripes
Mixture in tundra
3684m
3736m
3651m
3702m
3580m
SSW
SE
N
W
NW
Figure1. Study area map indicating location of logger sites and their location within RMNP in
Colorado.
Site location map created by Heather Burnett and Kristen Sanders using ArcGIS and ESRI data. Colorado
state highway map from Colorado Blogging. RMNP map from StateMaster.com.
Methods
RMNP is the location for ongoing research into the effects of climate change on the high alpine
tundra. Thanks to a study entitled Permafrost Characteristics along Trail Ridge Road, Rocky Mountain
National Park, CO, data loggers were installed in 2008. The installation method is described in depth in
this excerpt from the study by Dr. Jason Janke:
Thirty HOBO data loggers with two sensors (internal (A) and an external (B)) were installed
during July 2008. With the assistance of students, holes were drilled using a standard soil
auger, sensors were inserted, and holes were backfilled. Unfortunately, the rocky soil did
not permit the second sensor to be placed at a great depth. Internal surface sensors (A)
were installed at 10 cm depth, whereas external sensor (B) depths ranged from 30 to 85 cm.
Soil samples were obtained at each site for analysis of soil properties. For each sensor
location, elevation, slope, and aspect were measured. Loggers were launched and set to
record temperature at 2-hour intervals. High-resolution Global Positioning Satellite (GPS)
measurements were taken at each point to aid in relocation. Locations were also marked
with a ring of rocks around the data logger.
Data was downloaded in July of 2009 and then again in August of 2010. From earlier
research sites 3, 7, 10, 17, and 25 were selected for further study. The data retrieved in August of
2010 was added to the July 2009 data and separated into fall, winter, spring, and summer. Fall was
classified as September through November, winter as December through February, spring as March
through May, and summer as June through July because the August data was incomplete. External
sensors are classified as surface and the internal sensor as ground. Ground and Surface were further
evaluated using Excel.
Seasonal classifications were used to judge differences between the two years. The
measurements were taken as follows: Fall September 1-November 30, Winter December 1-
February 28, Spring March1-May 31, and Summer June1- July 26. The month of August was not
included due to lack of comparable data. Averages, Standard Deviation, and t-tests were
conducted for each sensor across the two years for the sites to be evaluated. The two-tail t-test was
used to assess the years and determine if a temperate change did occur. From this conclusions
were drawn as to possible effects of vegetation, soil composition, aspect, and snow cover. The
study sites were chosen, out of a desire to use differing site compositions, where assumptions could
be made for the larger area. The t-tests and seasonal averages when compared give a scientific, as
well as an elementary view of the data.
Results
Site 3
Site 3 is the Eastern-most data logger located at an elevation of 3684m on an earth hummock with
a South-Southwest aspect (Table1, Figure1) (Janke, 2009). The mean surface temperature increased
between year 1 and year 2 (See Table2), indicating a warming trend. The maximum surface temperature
of 14.79⁰C was recorded on July 24, 2010, and a maximum ground temperature of 8.46⁰C on December
11, 2009. The minimum surface temperature fell to -11.51C° on December 10, 2009, followed by a
minimum ground temperature of -7.38°C on December 11, 2009. The significantly colder surface
temperature between the surface and ground minimum measurements is possibly due to a lack of snow
cover. Snow cover insulates the surface and reduces extreme variation in temperature (Janke, 2009). The
largest variations in seasonal temperatures between year 1 and year 2 occurred during the winter months.
The surface logger showed a near 2⁰C decrease in year 2, and the ground logger recorded a 1.5⁰C
decrease. The significant difference between the spring surface measurements indicates that some snow
may have been present on the surface during year 2 as seen in Figure 2. The ground temperature remained
constant during the two years (Janke, 2009).
Figure2. Average seasonal temperature variations for Site 3
6
Seasonal Averages Site 3
Surface and Ground
Temperature °C
4
2
0
-2
Fall
Surface
Fall
Ground
Winter
Surface
Winter
Ground
Spring
Surface
Spring
ground
Summer Summer
Surface Ground
year1
year2
-4
-6
-8
Logger Site 3 Seasons
Site 7
Site 7 lies toward the South Eastern side of the study area at an elevation of 3736m with a
Southeast aspect, located on tundra below a rock outcrop (Table1, Figure1) (Janke,2009). The mean
surface temperature between the two years shows a warming trend for both the surface and ground
loggers. The surface and ground data revealed similar changes with temperatures rising approximately
2.5⁰C. This shows that there was little variance between the recordings and may be attributed to a strong
heat exchange between the surface and ground medium eliminating a thermal gradient. As seen in figure
3 seasonal averages remained relatively constant.
Figure3. Average seasonal temperature variations for Site 7
8
Seasonal Averages Site 7
Surface and Ground
Temperature °C
6
4
2
Year 1
0
-2
Fall
Surface
Fall
Ground
Winter
Surface
Winter
Ground
Spring
Surface
Spring
Ground
Summer
Surface
Summer
Ground
Year 2
-4
-6
-8
Logger Site 7 Seasons
Site 10
Site 10 has a northern aspect and is positioned at an elevation of 3651m (Table1, Figure1). This
study area is experiencing solifluction, which is the downward movement of saturated sediment and
debris in a periglacial environment. The mean annual surface temperature actually decreased from year
one to year two as displayed in tables 5. The mean annual ground temperature increased as seen in table
6. Although both the surface and ground experienced changes the rate at which they warmed/cooled was
very small with a 0.2 °C change at the surface, and a 0.038 °C change at depth. The slight
cooling/warming and little variation in temperature could be explained by the fact that northern facing
slopes receive the least amount of sunlight and site 10 had a frost index of 0.6 from 2008 – 2009
(Janke,2005). As depicted in Figure 4, there is minimal seasonal variation between the two years.
Figure4. Average seasonal temperature variations for Site 10
Surface and Ground Temperature °C
8
Seasonal Averages Site 10
6
4
2
Year 1
0
-2
Fall
Surface
Fall
Ground
Winter
Surface
Winter
Ground
Spring
Surface
-4
-6
-8
Logger Site 10 Seasons
Spring
Ground
Summer
Surface
Summer
Ground
Year 2
Site 17
Site 17 is located at a 3702m elevation between stone stripes with a Western aspect (Table1,
Figure1) (Janke, 2009). The surface yearly mean increased from -1.74°C to 2.36°C, indicating an overall
warming trend at the surface (See Table 8). The ground yearly mean temperature slightly decreased
overall from year 1 to year 2 (See Table9). The minimum surface temperature was -16.28°C on December
10, 2009. The maximum surface temperature in the two years was 14.94°C on July 24, 2010. The
minimum ground temperature in the two years was -11.005°C on December 11, 2009. The maximum
ground temperature in the two years was 5.95°C on July 26, 2010. There appears to be a correlation
between the surface and ground maximum and minimum temperatures. The surface maximum
temperature occurred on July 24, 2010, with the ground maximum temperature occurring two days later
on July 26, 2010. A similar correlation was observed between the minimum ground temperatures, where
the surface minimum occurred on December 10, 2009, followed by the ground minimum temperature the
following day. This could be attributed to the insulative properties of the soil that cause a lag time
between the surface and ground as the soil catches up to the surface during heat exchange. As seen in
Figure 5, seasonal variations were minimal between the two years.
Surface and Ground Temperature
°C
Figure5. Average seasonal temperature variations for Site 17
8
Seasonal Averages Site 17
6
4
2
0
-2
-4
Fall
Surface
Fall
Ground
Winter
Surface
Winter
Ground
Spring
Surface
Spring
Ground
Summer Summer
Surface Ground
Year 1
Year 2
-6
-8
-10
-12
Logger Site 10 Seasons
Site 25
Site 25 has a Northwest aspect and is located at an elevation of 3580m. This study site has a
rocky mixture in tundra (Janke, 2005). The mean annual surface temperature increased by 0.6404 °C
indicating warming. The mean annual ground temperature decreased by 0.53442 °C indicating there was
cooling from year one to year two (table 10). The maximum surface temperature was recorded on
8/1/2008 at 22.68 °C and the minimum surface temperature at -17.99 °C occurring on 12/10/2009. The
maximum ground temperature occurred on 8/2/2008 and was recorded at 8.965 °C. The minimum ground
temperature was observed at -10.092°C and was recorded on 2/16/2010. During the winter season and
into spring, site #25 displayed temperatures below zero, with little variation between years one and year
two. During the summer season the surface temperatures between the two years display no difference and
temperatures continue to remain above zero through the summer, and into the fall season with very little
variations seen in figure 6.
Mean Temperature °C
Figure6. Average seasonal temperature variations for Site 25
10
8
6
4
2
0
-2
-4
-6
-8
-10
-12
Site 25 Seasonal Averages
Fall
Surface
Fall
Ground
Winter
Surface
Winter
Ground
Spring
Surface
Spring
Ground
Summer Summer
Surface Ground
year1
year2
Seasonal Surface and Ground Site 25
The site that experienced the most significant warming during the two year period was site 17.
The surface data revealed an average increase of 4.1⁰C between the two years. Sites 3 and 7 showed a
small rise in temperature. According to the t-Critical- two tail tests, sites 3,7,17, and 25 showed warming
with a t-stat above 1.96. Site 10 did not display a statistically significant change. The average surface soil
temperature for year 1 for all sites evaluated is 0.246⁰. The average surface reading for year 2 was
1.126⁰C, which indicates that warming did occur during the two year period. The mean ground
temperature for all sites in year 1 was -0.924⁰C, and for year 2 was -0.775⁰C indicating that on average
the ground remained frozen throughout the two years. The yearly average surface and ground
temperatures comparisons can be seen in Figures 7 and 8. It can be seen that ground temperatures
remained consistently cooler than surface temperatures.
Figure7. Surface mean temperature at logger sites for years 1 and 2
Surface Yearly Mean
Temperature °C
3
2
1
Year 1
0
Year 2
Site 3
Site 7
Site 10
Site 17
Site 25
-1
-2
Logger Sites
Figure8. Ground mean temperatures at logger sites for years 1 and 2
2
Ground Yearly Mean
Temperature °C
1.5
1
0.5
0
-0.5
Site 3
Site 7
Site 10
-1
Site 25
Year 1
Year 2
-1.5
-2
-2.5
-3
Site 17
Logger Sites
Discussion
Frozen soils are sensitive to climatic changes and the ecosystems that depend on them for
survival are fragile. Along with vegetation, soil nutrient retention, carbon sequestration and slope stability
are all impacted by the reduction of permafrost (Wang, G.et al. 2005). The results of this study show that
soil temperatures did indeed increase over the two year period examined. If this trend continues it may
serve as an indicator of climate change in the Front Range vicinity. The consequences of warming in
RMNP are dire as it could alter the terrain and ecology of the park. From evidence collected at the study
site over a broader period of time the effects of climate change on a global scale can be evaluated. This
study found that along with other research of temperature variability; snow cover, soil composition and
aspect significantly affect the temperature readings of the loggers, making it difficult to arrive at a
definitive conclusion.
Conclusion
Individual seasonal change was analyzed as well as yearly and specific site changes. During the
winter season a statistically significant (SS) warming was seen at the surface and at depth for all five
sample study sites. Although SS changes were observed in some cases whether at the surface or at depth
there is no distinct trend of warming or cooling during the summer season. The spring season had an
overall SS warming with the exception of the observed cooling seen at sites 10 and 3. There is no distinct
trend of warming or cooling during the fall season from 2008-2010 although SS changes were seen in
some cases. Previous studies coincided with our research findings that RMNP is likely experiencing
warming, especially during the winter and spring months.
Looking at the 5 sample study sites individually we were able to determine which sites were
experiencing the greatest change, and how the annual mean temperatures changed at each site from year
one to year two. Sites 17 and 25 experienced the greatest change with regard to observed heating/cooling
in relation to a no observed difference analyzed in each season from the surface and at depth observations.
Site 10 experienced an annual mean temperature change that trended towards cooling at the surface and
warming at depth. Site 25 displayed a warming trend at the surface and a cooling trend at depth from
year one to year two. Site 7 showed warming in both the surface and ground mean annual temperature
changes. Warming was observed at the surface and at depth for site 17 as well which also experienced
the largest change of all the five study sites. Site 3 was found to be cooling at depth and warming at the
surface. When examining all of temperature data using the t-test from each site it was found that overall
each one of our sample sites were warming with the exception of site 10 which experienced no significant
change. Our findings lead us to believe that the RMNP region is warming.
The strongest influences on soil temperature include slope, aspect, snow cover and the presence
of permafrost. Our findings indicate that none of our 5 sample sites had permafrost. Depending on these
factors soil temperatures can be highly to slightly variable in change from year to year. In order to
determine the rate and magnitude of change that the RMNP region will experience more research and
analysis will need to be done in the future. Other factors such as air temperatures and snow depth may
also be included in future studies to provide more insight on how these variables affect the climates and
micro-climates of an alpine region.
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