This research examines environmental and hydrological consequences of land use change in South America with the goal of understanding how conversion of grasslands to plantation forests affects groundwater, soil salinity and nutrient availability. The research 1) compares paired native grasslands and plantations in Argentina and Uruguay for their growth and water use, 2) initiates measurements of groundwater and stream chemistry at 19 paired grassland and forested watersheds, and 3) develops a framework for predicting increases in aboveground productivity and water use with forestry based partly on groundwater characteristics, including the depth to ground water, the salinity of the water, and the tolerance of different tree species to that salinity. An additional goal is to understand how different tree species alter the chemistry and hydrology of ecosystems, particularly through their ability to use groundwater at different depths and of different salinities.
The activities outlined in this proposal provide several benefits to society. One is a model of salinization that bears directly on drinking-water quality in the region, since forests are being extensively planted into grasslands that overlay shallow fresh water, the primary source of renewable drinking water. The research will provide information on the environmental costs and benefits of conversion of grassland to forests as a means of sequestering carbon from the atmosphere. Another benefit is information that leads to more sustainable forestry practices, including a more complete accounting of approaches for biological carbon sequestration. The project includes significant contributions from high-school students and undergraduates and provides them with an early introduction to science research.
