MS, University of Cincinnati, 2012, Arts and Sciences: Geology

Soil organic carbon affects soil fertility and agricultural production, and organic C storage can also mitigate increasing atmospheric CO2 concentrations on decadal time scales or longer. However, soil organic C storage is dependent on climatic conditions, especially temperature and precipitation, and changes in these parameters associated with climate change can act as feedback mechanisms to atmospheric CO2 concentrations. The objective of this study is to evaluate regional organic carbon abundance in northern India across orographically-limited precipitation regimes. We hypothesized that the existence of a soil organic carbon (SOC) gradient corresponding to these bioclimatic barriers, a result of this large precipitation and assumed vegetation discrepancy. Samples were collected from the Kulu Lesser Himalaya, Lahul Himalaya, and Zanskar and measured for SOC/TN inventory as well as ?14C and d13C analysis of soil organic matter (SOM). Average annual carbon accumulation and C turnover time were estimated for selected soil chronosequences, and results varied widely among the areas investigated. It was revealed that soil organic C stocks in the Indian Himalaya are sensitive to precipitation, C3 vegetation has been consistently dominant up to ~6ka B.P., and rates of accumulation and turnover are influenced greatly by variations in climate, vegetation, and topography. Examining the distribution of soil organic carbon stock can be useful in helping to predict the potential effects of warming and precipitation on C storage in this region.

Committee: Amy Townsend-Small PhD (Committee Chair); Craig Dietsch PhD (Committee Member); Lewis Owen PhD (Committee Member) Subjects: Geochemistry