Airsheds, Isotopes and Ecosystem Metabolism in Mountainous Terrain

生态学家的一个基本任务是了解生态系统和气候之间复杂的相互作用。我们想要预测生态系统将如何对温度、降水和二氧化碳浓度的变化做出反应，进而预测生态系统本身将如何影响气候变化。在这方面已经取得了巨大的进展。然而，尽管包括世界上许多最具生产力的生态系统在内的20%的地球陆地表面被山脉覆盖，但目前用于检查生态系统代谢过程的几乎所有测量工具都只能在平坦的土地上使用。从“平地”研究中发展出来的概念适用于山地地形吗？为了回答这个问题，我们需要新的方法来研究生态系统过程。这个项目采用了一种新颖的方法：我们建议利用“冷空气排水系统”。在某些条件下，冷空气实际上下沉并通过山区系统“排水”，形成一个在地形和概念上类似于分水岭的空气棚。就像流域中的水携带溶解物质一样，流域内的空气也含有沿着气流路径吸收的小颗粒和气体。在这个项目中，我们将专注于浓度以及同位素组成的微小变化，或质量，一种特殊的气体，二氧化碳。一个跨学科的科学家团队将仔细研究空气排水系统、排水系统中二氧化碳的碳同位素组成和生态系统代谢过程。我们将测试同位素变化可以作为生态系统代谢变化指标的总体假设。该项目将安装在一个长期的生态研究站，该研究站已经为公立学校、教师和公众制定了良好的教育计划。我们预计，为这个项目在森林内安装的“高科技”设备，以及项目目标，将具有广泛的兴趣和教育价值。

A fundamental quest for ecologists is to understand the complex interactions between ecosystems and climate. We want to predict how ecosystems will respond to changing temperature, precipitation and carbon dioxide concentrations, and, in turn, how ecosystems themselves can influence climate change. Enormous progress has been made toward this quest. However, although 20% of the earth's land surface, including many of the world's most productive ecosystems, is covered by mountains, almost all of the measurement tools currently available to examine metabolic processes of ecosystems can only be used on flat land. Do the concepts developed from "flat land" studies apply to mountainous terrain? To answer this question, we need new ways to study ecosystem processes. This project takes a novel approach: we propose to take advantage of "cold air drainage systems". Under certain conditions, cold air actually sinks and "drains" through mountainous systems, creating an airshed that is similar topographically as well as conceptually to a watershed. Just as water in watersheds carries dissolved materials, air within airsheds contains small particles and gases that it picks up along the airflow path. In this project we will focus on the concentration as well as tiny variations in the isotopic composition, or mass, a particular gas, carbon dioxide. An interdisciplinary team of scientists will closely examine air drainage systems, the carbon isotope composition of carbon dioxide in the drainage systems, and ecosystem metabolic processes. We will test the overall hypothesis that the variations in isotopes can be used as indicators of change in ecosystem metabolism. The project will be installed in a long-term ecological research station that has well-developed educational programs for public schools, teachers and the general public. We anticipate that the "high tech" equipment installed within the forest for this project, as well as the projects goals, will be of broad interest and educational value.