Groundwater Use and Salinity Dynamics at Forested Sites of Temperate South America

这项研究考察了南美洲土地利用变化的环境和水文后果，目的是了解草原退耕还林对地下水、土壤盐分和养分有效性的影响。这项研究1)比较了阿根廷和乌拉圭成对的本地草地和种植园的生长和用水情况，2)在19个成对的草原和森林流域开始测量地下水和溪流化学，3)建立了一个框架，部分基于地下水特征，包括地下水深度、水的盐度和不同树种对盐分的耐受性，预测地上生产力的增加和林业用水量的增加。另一个目标是了解不同树种如何改变生态系统的化学和水文学，特别是通过它们利用不同深度和不同盐度的地下水的能力。一种是与该地区饮用水质量直接相关的盐碱化模式，因为森林被广泛种植到覆盖着浅淡水的草原上，浅淡水是可再生饮用水的主要来源。这项研究将提供关于退耕还林作为一种从大气中封存碳的手段的环境成本和收益的信息。另一个好处是信息导致更可持续的林业做法，包括对生物碳封存方法进行更完整的核算。该项目包括高中生和本科生的重大贡献，并为他们提供了早期的科学研究入门。

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.