Effects of Species Traits and Biodiversity on Ecosystem Processes in Arctic Tundra

本研究旨在探讨北极冻原植物物种多样性和植物生长方式对生态系统碳氮循环的影响。 此外，它将测试植物的功能群是否是了解植被对生态系统过程的控制和生态系统对扰动的反应的所有物种的详细生理信息的适当近似。 努力将集中在北极苔原，一个高度优先的生态系统。 提出了一种建模与实验相结合的方案。 在实验中，在苔原的多样性将被操纵，通过删除不同的生长形式的苔原植物（代表功能组在苔原），所有可能的组合，从两种生长形式的物种，并对生态系统的C和N循环的影响将被测量。 将开发模拟模型，以比较单个植物物种的生长对生态系统一级资源供应和循环的影响，以及通过平均不同物种在生长形式中的特征而构建的功能组的影响。 将对每个主要物种的植物生长和生长期间的竞争相互作用进行建模。 将比较物种或功能群的分布和净生产力、生态系统净初级生产力和当前气候条件下养分循环的模型预测。 从模型中删除或引入物种或功能组，以及由食草动物或气候变化引起的扰动的影响也将被检查，并将与删除物种和生长形式的实验结果进行比较。 这项研究是新颖的，因为它是第一个实验测试的物种和生长形式多样性对生态系统过程的影响，在冻土带，它是第一次尝试模拟植物物种的影响和它们的竞争相互作用对生态系统过程在北极冻土带。 这对于理解物种和功能群多样性在生态系统过程中的作用至关重要。

The objective of the proposed research is to explore the effects of biodiversity in plant species and of plant growth forms on ecosystem cycling of C and N in arctic tundra. In addition, it will test whether functional groups of plants are an adequate approximation for detailed physiological information on all species in understanding vegetation controls over ecosystem processes and the response of ecosystems to perturbations. Effort will be focused on arctic tundra, a high priority ecosystem. An integrated program of modeling and experimentation is proposed. Experimentally, diversity in the tundra will be manipulated by removing different growth forms of tundra plants (which represent functional groups in the tundra), and all possible combinations of the species from two growth forms, and effects on ecosystem C and N cycling will be measured. Simulation models will be developed to compare the effects of growth of individual plant species on ecosystem-level resource supply and cycling with those of functional groups constructed by averaging the characteristics of the different species in the growth form. Plant growth for each of the major species and competitive interactions during growth will be modeled. Model predictions of the distribution and net productivity of species or functional groups, ecosystem net primary productivity, and nutrient cycling under current climatic conditions will be compared. Effects of removing or introducing species or functional groups from the models, and of perturbations caused by herbivory or variable climate will also be examined, and will be compared with experimental results of removing species and growth forms. This research is novel because it is the first experimental test of the effects of species and growth form diversity on ecosystem processes in the tundra, and it is the first attempt to model the impact of plant species and their competitive interactions on ecosystem processes in arctic tundra. This is critical to understanding the role of species and functional group diversity in ecosystem processes.