Effects of climate-driven species change on forest carbon and nitrogen cycling

大多数关于气候变化对森林影响的研究都侧重于预测的温度和降水量变化的直接影响。 然而，很明显，除了气候对森林生态系统功能的直接影响外，还将产生由气候驱动的树种组成变化所造成的间接影响。 随着气候变暖，北美树种的分布范围将逐渐向北移动。 在任何特定的地点，这将导致树种的变化，有利于那些适应温暖气候的物种。 由于树种在许多方面都是独特的，物种组成的变化将改变森林生态系统的功能。 大多数预测气候变化对森林影响的计算机模型都没有包括这种物种变化。 这项研究将通过将两个独立的计算机模型与一个预测树种范围如何随着气候变化而变化的统计模型和一个预测物种变化对森林功能关键方面的影响的模拟模型联系起来来填补这一空白，如生产力，碳储存和氮循环。 这些相互联系的模型将用于预测下一个世纪气候变化的几种现实情况下气候变化对森林功能的影响。 这一初步努力的重点是美国东北部，但是，如果能够获得关于最重要树种特征的充分信息，这种方法和模式有可能适用于全国乃至全世界的森林。该项目是卡里生态系统研究所和美国农业部林务局的一项合作努力，该研究将对研究气候变化的科学界产生重大影响，使人们关注树种组成的变化如何影响森林的功能和恢复力这一重要但往往被忽视的问题。 此外，这显然是一个与政策相关的问题，对于东北部森林流域的森林生长，生物多样性，碳封存和空气污染源氮的保留问题非常重要。 来自卡里研究所和林务局的主要研究人员将使政策制定者、自然资源管理者和公众能够获得这项研究的结果。研究结果，包括模型结果的技术细节，将在网站上公布，由项目工作人员维护和支持。 本项目开发的模型将有助于分析全球变化的其他重要问题，包括由非本地害虫和病原体的引入以及非本地植物的入侵引起的树种变化。该项目还将为一名博士后助理和两名本科生提供教育机会。

Most studies of the effects of climate change on forests have focused on the direct effects of predicted changes in temperature and precipitation. However, it is clear that in addition to the direct effects of climate on the functioning of forest ecosystems, there will also be indirect effects caused by climate-driven changes in tree species composition. As the climate warms, the ranges of North American tree species will gradually shift northward. At any given location, this will produce a change in tree species, favoring those species adapted to warmer climates. Because tree species are unique in many different ways, the change in species composition will alter the functioning of the forest ecosystem. This species change is not included in most computer models that predict the effects of climate change on forests. This study will fill that gap by linking two separate computer models with a statistical model that predicts how the ranges of tree species will shift as the climate changes, and a simulation model that predicts the effects of the species change on key aspects of forest function such as productivity, carbon storage, and nitrogen cycling. The linked models will be used to forecast the effects of climate change on forest functioning for several realistic scenarios of climate change over the next century. This initial effort is focused on the Northeastern U.S., but the approach and the models are potentially applicable to forests throughout the country, and even throughout the world, if sufficient information is available about the characteristics of the most important tree species. This project is a collaborative effort involving the Cary Institute of Ecosystem Studies and the USDA Forest Service.This research will have significant impacts on the scientific community studying climate change by focusing attention on the important, but often ignored, issue of how changes in tree species composition will affect the functioning and resillience of forests. In addition, this is clearly a policy-relevant question that is important for issues of forest growth, biodiversity, carbon sequestration, and retention of air pollution-derived nitrogen in forested watersheds in the Northeast. The principal investigators from the Cary Institute and the Forest Service will make the results of this research available and accessible to policy makers, natural resource managers, and the general public. The results of the study, including the technical details of the model results, will be available on web sites that will be maintained and supported by project staff. The models developed in this project will be useful for analysis of other important issues of global change, including tree species change caused by introductions of non-native insect pests and pathogens and by invasions of non-native plants. This project will also support educational opportunities for one postdoctoral associate and two undergraduate students.