Grantee Research Project Results

Do Savanna Plant Life-Forms Spatially Partition Resources to Limit Competition and Maximize Productivity: A Test of Walter's Two-Layer Model in Longleaf-Pine Wiregrass Savanna

EPA Grant Number: U916170
Title: Do Savanna Plant Life-Forms Spatially Partition Resources to Limit Competition and Maximize Productivity: A Test of Walter's Two-Layer Model in Longleaf-Pine Wiregrass Savanna
Investigators: Ford, Chelcy R.
Institution: University of Georgia
EPA Project Officer: Packard, Benjamin H
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $124,969
RFA: STAR Graduate Fellowships (2003) Recipients Lists
Research Category: Academic Fellowships , Biology/Life Sciences , Fellowship - Forestry , Ecological Indicators/Assessment/Restoration

Objective:

The objective of this research project is to link water sources used with whole ecosystem water use and productivity.

Approach:

Although savannas occupy 15 percent of the earth's surface, the physiological processes of water use and carbon gain in savannas have received little attention. Recent studies in savannas suggest that carbon gain may depend on the water sources used by the two dominant life forms. If this is the case, then process models that rely on abiotic variables such as absorbed radiation and intercepted precipitation to predict evapotranspiration and primary productivity may be underestimating these parameters. Working in an endangered, longleaf pine-wiregrass savanna, we ask the following questions:

• What water sources and how much water do trees and grasses use?
• How much do these life forms contribute to total ecosystem water flux, and thus how much do the different water sources contribute?
• How much water is hydraulically redistributed by the root systems of trees?
• Do water and nutrient availability interact with carbon gain for these life forms?

These will be examined over a natural hydrologic and manipulated nitrogen gradient using stable isotope techniques, Penman-Monteith modeling, and sap flux methods.

This study ecosystem is one of the most endangered ecosystems in the United States. This research will result in the first quantification of the carbon, nitrogen, and water dynamics of this system and, thereby serve as a functional benchmark for conservation efforts. Not only will the results impact conservation efforts, they also will impact remote sensing and scaling efforts. Remotely sensing productivity and evapotranspiration often are coupled with ground-based models for validation. This research will result in the first ground-based, ecosystem-scale transpiration models for this ecosystem.

Supplemental Keywords:

fellowship, savannas, savanna plant life-forms, longleaf pine wiregrass, evapotranspiration.

Progress and Final Reports:

2003

2004

Final