Scott Clingan Winter Ecology Spring 2014 Terrestrial Carbon Cycle Soil respiration estimated to account for 2038 of annual biogenic CO 2 emissions Scott 2002 Increased Respiration from global warming lower carbon sequestration positive feedback ID: 783681
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Slide1
The Influence of Vegetation Type on Winter Soil Respiration Rates
Scott
ClinganWinter Ecology Spring 2014
Slide2Terrestrial Carbon Cycle
Soil respiration estimated to account for 20-38% of annual biogenic CO
2 emissions (Scott 2002)
Increased Respiration from global warming = lower carbon sequestration (positive feedback?)
Slide3How does vegetation type influence soil respiration?
Snow depths<1m, vegetation type exerts a
signifant influence on landscape level CO2 respiration (Grogan 2012)Vegetation influences abiotic and biotic factors of respiration
Soil moisture, soil temp, litter quantity/quality, litter depth (Fu 2013)
AET (Actual Evapotranspiration) good predictor of soil respiration
High levels of spatial heterogeneity
Slide4Questions
Q1: Does vegetation type influence winter soil respiration?
Hypotheses:H1:Vegetation type influences the amount of winter soil respiration H0: Winter respiration rates do not differ across vegetation thypesQ
2: Does soil moisture impact soil respiration ratesHypotheses:
H
1
: High soil moisture content will inhibit soil respiration rates in the winter
H
0
: Soil Moisture does not effect soil respiration rates
Slide5Methods
PP Systems SRC-1 Soil CO2 Flux System
Measured soil CO2 emissions over 120 seconds3 Vegetation Types (~100cm snow depth)Aspen (Populus tremuloides)Lodgepole
Pine (Pinus contorta)
Mixed Grass Meadow (various species)
2 Replicates of each type
3 Subsamples per replicate
Supplemental Data
1
Soil Moisture (0-4)
Amount of Organic Matter (0-5)
Analyzed with “R” statistical software
1
Collaboration with Coin Pettinati
Slide6Site Characterization
Elevation ~9,500 ft.
Mean Annual Precipitation: 20 to 40 inches
Mean Annual Air Temp 36-39 degrees F
Frost-Free Period: 30 to 50 days
Soils
1
Aspen: Slight/moderate decomposition to sandy loam
Lodgepole: Cobbly silt loam to Very Cobbly Silt Loam
Meadow- Organic Layer Cobbly to gravely sandy loam
Glacial till and/or alluvium derived from igneous and metamorphic rock
1
R
etrieved from:
www.websoilsurvey.nrcs.usda.gov
3/6/2014
Slide7Replicate Results
Slide8Significance
Lodgepole-Aspen: p<.001
Lodgepole-Meadow: p<.001Aspen-Meadow: p=0.5264186(f-value 119.7)
Comparison of Respiration Rates
Slide9Is soil moisture a good predictor of soil respiration rates?
Significance
Low-High: p=0.5264186Moderate-High: p<0.001Moderate-Low: p<0.001(
fvalue= 119.7)
Moisture Values
Low: 1&2
Moderate: 3
High:
Slide10Does Litter Amount influence Soil Respiration Rates?
Significance
Medium-High: p<0.001Medium/High-High: p<0.001Medium/High-Medium: p<0.5265186
(f value 119.7)
Slide11Summary
Vegetation Type does influence soil respiration rates….however
Aspen respiration is lower that other studiesLimiting Factor?Litter amount directly influences ratesWhat about quality?Research litter C:N ratios
ProblemsHigh levels of spatial heterogeneity Highly variable (diurnal, seasonal,
interannual
time scales)
Slide12Questions?
Special thanks to the following people who contributed to this project:
Tim Kittel, Kelly Matheson, Derek Sweeney, Colin Pettinati, Angel Bigas, Evan Esfahani
Slide13References
Fu, Xiaoli, et al. "Soil Respiration as Affected by Vegetation Types in a Semiarid Region of China."
Soil Science and Plant Nutrition 59.5 (2013): 715-26. Print. Grogan, Paul. "Cold Season Respiration Across a Low Arctic Landscape: The Influence of Vegetation Type, Snow Depth, and Interannual Climatic Variation." Arctic Antarctic and Alpine Research 44.4 (2012): 446-56. Print. Merbold, Lutz, Nele Rogiers, and Werner
Eugster. "Winter CO2 Fluxes in a Sub-Alpine Grassland in Relation to Snow Cover, Radiation and Temperature." Biogeochemistry 111.1-3 (2012): 287-302. Print. Morgner
,
Elke
, et al. "The Importance of Winter in Annual Ecosystem Respiration in the High Arctic: Effects of Snow Depth in Two Vegetation Types."
Polar Research
29.1 (2010): 58-74. Print.
Scott-Denton, Laura E., Kimberlee L. Sparks, and Russell K. Monson. "Spatial and Temporal Controls of Soil Respiration Rate in a High-Elevation, Subalpine Forest."
Soil Biology and Biochemistry
35.4 (2003): 525-34. Print.