This dissertation research aimed to quantify current soil organic carbon (SOC) stocks across Louisianas landscape, examine the spatial relationships between SOC and terrain factors at the watershed and river basin scales, and predict SOC changes in surface soils during future climate change. Using Louisiana as an example, a spatially-explicit modeling framework was developed that is conducive to watershed-scale prediction of soil carbon stock and change. SOC densities at the watershed scale were estimated using the USDA NRCS Soil Geographic Database (STATSGO). Louisiana watersheds and National Land Cover Database (NLCD) were used to aggregate total soil carbon and estimate average soil carbon density. Watershed drainage densities and slopes were quantified with 1:24 K Digital Elevation Models (DEM) data and the Louisiana hydrographic water features. Potential changes in SOC under 0.5° x 0.5° high-resolution climate change projections in Louisiana were simulated using a RothC model at a watershed scale under three greenhouse gas emissions scenarios (A1FI, A2, B2) based on the HadCM3 climate model. LIDAR and DEM datasets were used to assess the spatial distribution of potential inundated coastal areas; estimate the current wetland areas, SOC storage, and nitrogen contents at risk in Louisiana, classified by the National Wetlands Inventory (NWI) and DEM datasets. The research found that SOC density ranged from 22 to 108 tons/ha in the upper 30-cm soil at the watershed scale, with the highest density in emergent herbaceous wetlands. Among Louisianas 12 river basins, the Barataria, Terrebonne, and Lake Pontchartrain Basins in southeast Louisiana showed the highest SOC density. SOC density was positively correlated with watershed drainage density (r2=0.43), but negatively correlated with watershed slope gradient (r2=0.52) and elevation (r2=0.50). The modeling study on climate change effects showed that SOC storage in the top 30-cm soil layer of Louisiana forests, croplands, and grasslands would significantly decrease under all climate change scenarios. Coastal areas in southeastern Louisiana have some freshwater and estuarine wetland ecosystems that store a large quantity of organic carbon. Much of these areas have elevations less than 100 centimeters and are, therefore, prone to inundation of sea level rises during future climate change.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-01212010-151353 |
| Date | 26 January 2010 |
| Creators | Zhong, Biao |
| Contributors | Nyman, John Andrew, Xu, Y. Jun, Wang, Jim Jian, Lam, Nina S., Theegala, Chandra |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-01212010-151353/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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