Plant Diversity-Productivity Relationships: An Experimental Evaluation of the Roles of Local Ecological Processes and Species Pool Effects

了解地方和区域过程如何平衡以调节物种多样性是生态学的一个基本目标。我们的研究将考察局部尺度的生态相互作用和物种可用性在控制草原植物多样性、土壤养分供应和生境生产力之间的关系中的相对重要性。我们将在堪萨斯州的草原上同时进行两个析因田间试验。在实验1中，我们将通过在田间地块施用氮肥和磷肥来直接调控土壤养分供应和植物生产力。我们将通过使用多物种种子添加来操纵物种可获得性。在实验2中，我们将通过在自然草地生产力梯度上排列的地块中增加种子来控制物种的可用性。通过这些互补的方法，我们试图测试一组预测：(1)可用殖民地如何影响植物多样性和生产力之间的关系；(2)氮和磷供应如何相互作用，影响多样性-生产力关系的性质；(3)物种可用性如何影响不同养分供应和生产力条件下植被演替的速度和途径。我们正在寻求对植物群落组织的新见解，以及对草原多样性生产力模式发展过程的更好理解。

Understanding how local and regional processes balance to regulate species diversity is a fundamental goal in ecology. Our research will examine the relative significance of local-scale ecological interactions and species availability in governing relationships between grassland plant diversity, soil nutrient supply, and habitat productivity. We will conduct two factorial field experiments concurrently within a Kansas grassland. In experiment 1, we will directly manipulate soil nutrient supply and plant productivity by applying nitrogen and phosphorus fertilizers to field plots. We will manipulate species availability through the use of multi-species seed additions. In experiment 2, we will manipulate species availability via seed additions in plots arrayed across a natural grassland productivity gradient. With these complimentary approaches, we seek to test a set of predictions regarding: (1) how the pool of available colonists affects the relationship between plant diversity and productivity; (2) how nitrogen and phosphorus supply interact to influence the nature of the diversity-productivity relationship; and (3) how species availability influences rates and pathways of vegetation succession under different conditions of nutrient supply and productivity. We are seeking new insights into the organization of plant communities as well as an enhanced understanding of the processes governing the development of diversity-productivity patterns in grasslands.