1. DIFFERENCES IN SOIL RESPIRATION RATES BASED ON VEGETATION TYPE Maggie Vest Winter Ecology 2013 Mountain Research Station

2. 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).

3. 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).

4. 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.

5. 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

6. Results Aspen-Lodgepole P Value: 0.11 Aspen-Spruce P Value: 0.46 Lodgepole-Spruce P Value: 0.10

7. Other Factors Affecting Soil Respiration Snow Depth

8. Other Factors Affecting Soil Respiration Soil Temperature

9. Other Factors Affecting Soil Respiration Ground Litter

10. 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

11. 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.

12. 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.

13. Acknowledgements  Thank to Rob for being a field partner  Thanks to Tim, Derek, and the CU Mountain Research Center The End

14. 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.

15. Appendix CO2 Flux

16. Appendix Results