Decomposition and development: A comparison of CO2 flux at Sourdough Trailhead Cloe Dickson Winter Ecology, Spring 2018 Department of Ecology and Evolutionary Biology Mountain Research Station - University of Colorado Boulder Cloe Dickson 2018 Decomposition and development File type: pptx Size: Keywords: decomposition, microbial respiration, CO2 flux, Sourdough Trailhead

What is decomposition? The breakdown of organic matter into inorganic molecules Performed by bacteria, fungi in the soil Use respiration as an energy source for decomposition reaction (Boyd, 1995) Can measure CO2 flux to find decomposition rate Dependent on current conditions

How does decomposition work in the winter? Temperature is key (a limiting factor) “Insulating effect” of snowpack limits daily temperature fluctuations, creates conditions that are more conducive to decomposition process (Marchand, 2013) Duration of snowpack cover also important for decomposition rate (Bowman, 2001)

What is the question? Question: How does decomposition in Sourdough Trailhead parking lot compare to decomposition rates in areas where snowpack is not periodically removed? Do higher snowpack levels, such as snow banks pushed up by plowing, allow for decomposition at a higher rate than original snowpack?

Hypothesis As snow is removed (by plowing) … Ground loses essential snowpack insulation Temperature of ground decreases Decomposition is inhibited by environmental conditions As snow is pushed up into snow banks (by plowing) ... Ground gains essential snowpack insulation Temperature of ground increases Decomposition occurs due to optimal environmental conditions

Methods Necessary materials: shovel, CO2 analyzer, snow probe, temperature probe Clear snow (when necessary) to expose soil for testing Obtain temperature at surface using temperature probe Place CO2 analyzer into soil and press ‘Y’ Repeat three times at each study site Record information on data sheet (noting current environmental conditions such as snow depth, precipitation)

Methods Study site: Sourdough Trailhead parking lot, Nederland, CO Four specific sites used: (1.) middle of parking lot, (2.) edge of parking lot, (3.) 5m and (4.) 15m from lot Replicates and randomness (or lack thereof) Three pseudoreplicates at each study site (12 total) Plan versus reality

Results: single-variable ANOVA ANOVA tests the difference between the means of independent groups P-value is <0.001 Mean slope increases further from lot

Interpretation ANOVA test shows that data is statistically significant P-value is <0.001 with level of significance (alpha) of 0.05 Can reject null hypothesis, or notion that there is no difference in the means of the CO2 flux slopes Snow addition/removal changes environmental conditions (temperature) Can support alternate hypothesis, or notion that at least one CO2 flux slope is different in the four sites

Future research Important to know how ecosystem services are affected by humans Decomposition rates are altered by manual snow removal (i.e. plowing) and respond to snow removal negatively Can have larger implications on health of the surrounding ecosystem, natural resource management Research in the future should use many (true) replicates Study flawed by lack of randomness and lack of replication Also need to isolate other confounding variables (trees)

Summary Decomposition occurs in and around the Sourdough Trailhead parking lot Dependent on environmental conditions (temperature, snowpack) Trend of CO2 flux increases away from parking lot center Many other factors that go into determining decomposition rate should be considered Important in understanding human influence

Literature cited Bowman, W. D. & Seastedt, T. R. (2001). Structure and Function of an Alpine Ecosystem: Niwot Ridge, Colorado. Oxford University Press: New York. Boyd C.E. (1995) “Soil Organic Matter, Anaerobic Respiration, and Oxidation— Reduction.” Bottom Soils, Sediment, and Pond Aquaculture. Springer, Boston, MA Marchand, P. J. (2013). “The Changing Snowpack.” Life in the Cold. University of New England Press: Hanover, New Hampshire.