Collaborative Research on the Effects of Plant Species and Functional Types on Diversity, Ecosystem Function, and Ecosystem Response to Perturbation in Arctic Tundra

人类活动对地球环境和生态系统的影响越来越大，不仅通过对气候和元素循环的直接影响，而且还通过加快物种引进和繁殖的速度。 由于碳和营养物质在生物圈中循环，而植物物种在影响这些元素循环速率的性状上存在差异，因此物种的丰富度和多样性必然会影响生态系统的功能。 然而，在何种程度上个别植物物种影响生态系统功能和物种多样性和生态系统对扰动的反应之间的关系仍然是未知的。 在生态系统功能上，植物种间的相互替代程度如何？ 哪些关键性状决定了一种植物物种对养分循环的影响是否可以被其他物种取代？ 在阿拉斯加草丛苔原的一个野外实验将通过在施肥和不施肥的情况下去除不同的植物物种组合来研究这些问题。 研究人员将详细了解植物物种之间的相互作用如何控制施肥下营养物质的重新分配，因为营养物质是这个高度营养有限的生态系统中碳储存的主要控制因素。 他们还将跟踪潜在的新物种的引入，因为植物群落组成的变化，因为删除或施肥。这些结果将有助于揭示人类引起的环境扰动如何改变控制生态系统碳储存和植物物种丰富度和多样性的机制。

Human activities are increasingly affecting earth's environment and ecosystems not only through direct impacts on climate and element cycling, but also by increasing the pace of introductions and extinctions of species. Because carbon and nutrients are cycled through the biosphere and plant species differ in traits that affect the rates of cycling of these elements, the abundance and diversity of species must affect ecosystem function. However, the extent to which individual plant species affect ecosystem function and the relationship between species diversity and ecosystem response to perturbation are still largely unknown. To what extent can plant species substitute for each other in ecosystem function? What key traits determine whether a plant species' effect on nutrient cycling can be substituted by other species? A field experiment in Alaskan tussock tundra will examine these questions by removing different combinations of plant species in the presence and absence of fertilization. The investigators will obtain a detailed picture of how interactions between plant species control how nutrients are redistributed under fertilization, because nutrients are a primary control over carbon storage in this highly nutrient-limited ecosystem. They will also track potential introductions of new species as plant community composition shifts because of the removals or fertilization. The results will help reveal how human-induced environmental perturbations may change the mechanisms controlling ecosystem carbon storage and plant species abundance and diversity.This is a collaborative project with Michelle Mack (DEB-0212749)