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Harvard Forest REU Symposium Abstract 2010
- Title: Soil Carbon Dynamics at Harvard Forest: An Exploration of the Abiotic and Biotic Drivers of Soil Respiration for Future Use in Models
- Author: Joanna R Blaszczak (Cornell University)
- Abstract:
The global terrestrial carbon flux is being influenced by many changing and interacting environmental factors including increased nitrogen deposition, temperature increases, and subsequent changes in terrestrial biomass production. Within global carbon pools, the soil carbon stock is the largest, containing more than twice the carbon as terrestrial vegetation or the atmosphere. In this project, the effects of four different manipulation treatments on soil respiration (SR) were examined through measurements of the rate of carbon dioxide efflux (μMol*m-2s-1) from the soil using a portable gas analyzer. The various experimental plots were sampled four times over the course of eight weeks on the Prospect Hill tract of Harvard Forest and the results were analyzed with ANOVA tests. A chronic nitrogen deposition experimental site that has been ongoing for 20 years was sampled and no consistent statistical differences in SR between the control and N addition plots were found (hardwoods: p = 0.39; pine: p = 0.39). Measurements were taken in the DIRT (Detritus Input and Removal Treatments) site to examine the effects of biomass changes on SR and the results show consistent significant increases in SR rates with double litter fall as compared to a control plot (p = 0.001). Soil warming chamber plots were sampled and no significant SR differences were apparent between different temperatures or soil warming methods. Tree roots were excluded in trenched plots to separate out the heterotrophic (microbial) decomposition and autotrophic (root respiration) contributions to SR rates. The SR rates were only significantly higher in the control plots the fourth sampling round (p = 0.012). Soil respiration rates and their drivers are important to investigate before incorporating them into models making inferences about global carbon budgets. Future research should examine the interactive effects of the variables explored in this project.
- Research Category: Group Projects; Soil Carbon and Nitrogen Dynamics
