Process-level Investigations of Weathering Inputs to Base-poor Forest Ecosystems

在许多森林生态系统中，通过化学风化释放钙和其他矿质养分的速率远远超过大气输入的速率。因此，风化是取代溪水淋洗或森林采伐造成的矿物质养分损失的主要机制。最近的研究集中于钙和其他碱性阳离子(CB)在淡水酸化、酸化后生态系统恢复、长期森林生产力、鱼类死亡和山地森林红云杉衰退中的作用。我们对CB风化释放的机制和速率的了解不足，限制了我们对元素循环中观察到的和预测的变化进行批判性评估的能力。这项研究旨在确定新罕布夏州两个基本贫瘠森林流域的风化机制和风化速率。该项目旨在研究单个矿物、土壤剖面和流域的风化作用。将使用和比较几种估计风化速率的方法，包括地球化学质量平衡、矿物消耗估计、流域元素平衡和锶同位素分析。通过评估单个矿物对流域风化速率的贡献并研究土壤剖面内的风化模式，我们将提高在未来大气条件下预测CB循环和森林生产力变化的能力。

In many forest ecosystems, the rate of release of Ca and other mineral nutrients through chemical weathering far exceeds the rate of input from the atmosphere. Thus, weathering is the primary mechanism by which mineral nutrient losses in streamwater leaching or from forest harvesting are replaced. Recent research has focused attention on the role of Ca and other basic cations (CB) in the acidification of freshwaters, ecosystem recovery from acidification, long-term forest productivity, fish mortality and the decline of red spruce in montane forests. Our poor understanding of the mechanisms and rates of weathering release of CB limits our ability to critically evaluate observed and predicted changes in element cycles. This study is aimed at determining the mechanisms and rates of weathering in two base- poor forest watersheds in New Hampshire. The project is designed to study weathering on the scale of individual minerals, the soil profile and the watershed. Several methods of estimating weathering rates will be used and compared, including geochemical mass balances, mineral depletion estimates, watershed element balances and Sr isotope analysis. By evaluating the contributions of individual minerals to watershed weathering rates and studying the patterns of weathering within the soil profile, our ability to predict changes in CB cycling and forest productivity under future atmospheric conditions will be improved.