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Harvard Forest REU Symposium Abstract 2011
- Title: Assessing the Importance of Various Biotic and Abiotic Factors in Soil Respiration Modeling
- Author: Julianna Brunini (Harvard College (Harvard University))
- Abstract:
In order to understand global carbon cycling, we must understand soil respiration—the process by which plant roots and soil microbes exchange carbon dioxide (CO2) with the atmosphere. Though temporal patterns in soil respiration are relatively well-understood, spatial variation in soil respiration has proven more difficult to explain. This study investigated numerous variables—soil temperature, soil moisture, stand density, root density, and litter mass—as possible predictors of the spatial variation seen in soil respiration. We measured the CO2 efflux five times over the course of ten weeks at forty-nine sites throughout the Prospect Hill tract at the Harvard Forest. Using stepwise, multivariate regression to analyze the data, we found that soil temperature is the most consistent predictor of CO2 efflux, though it cannot explain CO2 efflux alone. Our best overall model incorporates a combination of biotic and abiotic variables, relating carbon flux to soil temperature, stand density, root density, and litter mass (AIC=570.54, 0.10 < r2 < 0.52 for the five cycles of measurement). However, models incorporating soil moisture content fit early measurements well, suggesting that moisture plays an important role in CO2 flux towards the beginning of the summer, but not towards the end. Thus, carbon cycling models must incorporate both biotic and abiotic factors, though further study is necessary to determine if the appropriate choice of biotic factors varies with the seasons.
- Research Category: Physiological Ecology, Population Dynamics, and Species Interactions
