The effects of vegetation on soil respiration rates under the snowpack

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DIFFERENCES IN SOIL RESPIRATION
RATES BASED ON VEGETATION TYPE
Maggie Vest
Winter Ecology 2013
Mountain Research Station
Introduction

Estimated 20% of the annual soil respiration occurs
during the winter.
 Estimates

range from 3% to 50% (Hobbie et al. 2000).
High variability across small spatial scales (Scott-Denton et
al. 2002).


Lack of understanding of the controlling factors in
mid- and high-latitude systems (Hobbie et al. 2000).
Soil temperature is the best predictor for soil
respiration (Scott-Denton et al. 2002).
Vegetation and Soil Respiration

Connection between vegetation type and soil
respiration at the landscape scale (Grogan 2012).
Total CO2 flux ranged from 34 to 126g CO2/C m^2 for
various vegetation types in the low arctic tundra in Canada.
 Ecosystem-specific interactions between snow depth,
vegetation cover, moisture, and litter production also affect
CO2 flux


Different decomposition rates between evergreens and
deciduous trees (Hobbie et al. 2000).
Hypothesis



The aim of this study is to determine the degree of
significance that surrounding vegetation has on soil
respiration during wintertime.
Question: Does the surrounding vegetation
significantly impact soil respiration rates in the
subalpine forests?
Hypothesis: Deciduous trees are likely to have higher
rates of soil respiration than conifers.
Methods

3 vegetation types
Aspen
 Lodgepole
 Spruce





3 Replicates for each site
Trees with 30cm< snow depth
Measured CO2 concentrations over a 2 minute period
Recorded site features: temperature of soil surface,
snow depth, soil moisture, amount of organic litter, litter
composition
Results
Aspen-Lodgepole P Value: 0.11
Aspen-Spruce P Value: 0.46
Lodgepole-Spruce P Value: 0.10
Other Factors Affecting Soil Respiration
Snow Depth
Snow Depth versus Vegetation
Aspen
y = 3E-23x14.01
R² = 0.999
P Value=0.02
0.5
0.45
0.4
Lodgepole
y = 0.761ln(x) - 2.429
R² = 0.787
P Value= 0.31
CO2 Flux (ppm)
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
30
32
34
36
38
Snow Depth (cm)
40
42
44
Spruce
y = 0.658ln(x) - 2.191
R² = 0.123
P Value= 0.77
Aspen
Lodgepole
Spruce
Power (Aspen)
Log. (Lodgepole)
Log. (Spruce)
Other Factors Affecting Soil Respiration
Soil Temperature
Lodgepole
Aspen
y = 0.055x
0.150x + 0.441
0.940
R² = 0.951
0.869
P Value= 0.14
0.24
Soil Temperature versus Vegetation
0.5
0.45
0.4
CO2 Flux (ppm)
0.35
0.3
0.25
Spruce
y = -0.103x - 0.228
R² = 0.548
P Value= 0.47
Aspen
0.2
0.15
0.1
Lodgepole
0.05
Spruce
0
-6
-5
-4
-3
Temperature (C)
-2
-1
0
Other Factors Affecting Soil Respiration
Ground Litter
Organic Litter versus Vegetation
0.5
Aspen
y = 0.000x5.469
R² = 0.975
P Value= 0.10
0.45
0.4
CO2 FLux (ppm)
0.35
Lodgepole
y = 0.024x2.025
R² = 0.870
P Value= 0.23
0.3
0.25
Spruce
y = 0.091x0.594
R² = 0.485
P Value= 0.51
0.2
0.15
0.1
Aspen
Lodgepole
Spruce
0.05
0
1
2
3
Scale of Organic Litter
4
Results

Overall results were insignificant
 Aspen
CO2 flux and snow depth were only significant
data

Results suggest expected trends of aspens having
higher soil respiration than the evergreens
Discussion


Vegetation potentially impacts the rate of soil
respiration
Errors
 Short
time scale of project
 Small sample size

Further research is needed in order to determine
the degree of significance that vegetation has on
soil respiration rates.
Summary

Winter time soil respiration has the potential to
significantly impact the annual net carbon balance
(Grogan 2012).


Results suggest expected trends of aspens having
higher soil respiration than the evergreens.
Further research is needed in order to determine
the degree of significance that vegetation has on
soil respiration rates.
Acknowledgements


Thank to Rob for being a field partner
Thanks to Tim, Derek, and the CU Mountain
Research Center
The End
References






Brooks, Paul D., S. K. Schmidt, and M. W. Williams. 1997. Winter production of CO2 and
N2O from alpine tundra: environmental controls and relationship in inter-system C and N
fluxes. Oecologia 110: 403-413.
Grogan, Paul. 2012. Cold season respiration across a low arctic landscape: the
influences of vegetation type, snow depth, and interannual climatic variation. Arctic,
Antarctic, and Alpine Research 44:446-456. 1938-4246-44.4.446.
Hobbie, Sarah E., J. P. Schimel, S. E. Trumbore, and J. R. Randersons. 2000. Controls over
carbon storage and turnover in high-latitude soils. Global Change Biology 6:196-210.
Scott-Denton, Laura, K. L. Sparks, R. K. Monson. 2003. Spatial and temporal controls of
soil respiration rate in a high-elevation, subalpine forest. Soil Biology and Biochemistry
35: 525-534.
Schadt, Christopher, M. P. Martin, D. A. Lipson, S. K. Schmidt. 2003. Seasonal Dynamics
of previously unknown fungal lineages in tundra soils. Science 302: 1359-1361.
Tuomi, M, T. Thum, H. Jarvinen, S. Fronzek, B. Berg, M. Harmon, J. A. Trofymow, S.
Sevanto, J. Liski. 2009. Leaf litter decomposition-estimates of global variability based on
Yasso07 model. Ecological Modeling 220: 3362-3371.
Appendix
CO2 Flux
Site 1
y = 0.036x + 468.7
R² = 0.871
P Value= 0.23
480
CO2 (ppm)
470
Site 2
y = 0.270x + 437.7
R² = 0.990
P Value= 0.06
460
450
Site 3
y = 0.405x + 428
R² = 0.997
P Value= 0.03
440
430
700
20
70
Site 2
y = 0.357x + 413.7
R² = 0.993
P Value= 0.05
Site 3
y = 0.463x + 556.9
R² = 0.997
P Value= 0.03
500
400
300
200
100
Lodgepole Site 1
0
Aspen Site 2
120
Time (seconds)
R² = 0.996
P Value= 0.04
600
Aspen Site 1
420
-30
20
70
Time (seconds)
Aspen Site 3
Spruce CO2 Flux
CO2 (ppm)
-30
Site 1
Lodgepole CO2 Flux y = 0.227x
+ 424.6
CO2 (ppm)
Aspen CO2 Flux
-30
Site 1
y = 0.081x + 506.1
R² = 0.895
P Value= 0.21
520
515
510
505
500
495
490
485
480
475
470
Site 2
y = 0.238x + 476.6
R² = 0.982
P Value= 0.10
Site 3
y = 0.130x + 475.7
R² = 0.912
P Value=0.09
Spruce Site 1
20
70
Time (seconds)
120
Spruce Site 2
Spruce Site 3
120
Lodgepole Site 2
Lodgepole Site 3
Appendix
Results
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