Evaluating the Role of Resource Heterogeneity in Restoring Grasslands

9603118 Knapp试图在农业利用之后将生态系统恢复到或多或少的“自然状态”，但通常达不到目标。虽然自然生态系统的某些属性可以迅速恢复，但自然生态系统和恢复的生态系统在结构或功能上的关键差异往往会持续很长时间。例如，恢复生态系统中的本地植物物种丰富度和多样性通常远低于未受干扰的可比生态系统，可能需要数十年或更长时间才能接近未受干扰的生态系统水平。高草草原生态系统尤其如此。虽然在高草草原中建立优势牧草的恢复工作通常是成功的，但在这些草原中提供了大量物种丰富度和多样性的不太常见的牧草和牧草的恢复工作却更加困难。本文主要研究了土壤资源异质性在草地恢复中的作用。大多数草地恢复工作发生在土壤资源均质化的原农田。相比之下，大多数自然群落的资源具有高度的空间异质性，这被认为可以增强植物物种的多样性。我们认为，困扰大多数恢复工作的植物物种多样性低的问题是由于生态系统从相对统一的资源可用性状态向资源可用性空间异质性模式的转换缓慢。我们的研究将验证如果从一开始就施加更大的资源异质性，在恢复过程中植物物种丰富度、多样性和群落异质性的恢复会更快。

9603118 Knapp Attempts to restore ecosystems to a more or less "natural state" following agricultural use have usually fallen short of their goals. Although some attributes of natural ecosystems can be restored quickly, often times critical differences in the structure or function of natural and restored ecosystems persist for long periods. For example, native plant species richness and diversity in restored ecosystems is usually much lower than in comparable undisturbed ecosystems, and may take decades or longer to approach undisturbed ecosystem levels. This is particularly true for tallgrass prairie ecosystem. Although establishment of the dominant grasses in tallgrass prairie restoration efforts usually has been successful, it has been more difficult to restore the less common grasses and forbs that provide much of the species richness and diversity in these grasslands. Our research focuses on the role that heterogeneity of soil resources may play in grassland restoration efforts. Most grassland restoration efforts occur on former agricultural fields, where soil resources have been homogenized. In contrast, most natural communities are characterized by a high degree of spatial heterogeneity in resources, which is assumed to enhance plant species diversity. We contend that the problem of low plant species diversity that plagues most restoration effort is due to the slow conversion of an ecosystem from a state of relatively uniform resource availability to one with a more spatially heterogeneous pattern of resource availability. Our research will test the hypotheses that recovery of plant species richness, diversity and community heterogeneity will occur more rapidly during the restoration process if greater resource heterogeneity is impose on the system from the beginning.