Why Do More Productive Habitats Have Fewer Species? An Experimental Field Investigation

在许多环境中，环境越丰富，它能支持的物种就越少。至少在湖泊、热带森林、半干旱平原和山腰以及海洋中是这样。树木和其他植物、陆生哺乳动物和各种水生无脊椎动物也是如此。对此还没有一般的解释被证明。然而，保护世界物种需要了解控制自然环境中物种数量的机制。这项研究将在该领域检验两个假设。1)随着产量的增加，其他形式的生命是否会篡夺某种形式的资源？例如，哺乳动物物种的数量是否因为鸟类和蚂蚁的食物而减少？2)栖息地是否变得更简单，随着产量的增加，一些专家失去了他们的生计？例如，在植物中发现的建筑形式的多样性是否会减少，从而导致一些哺乳动物物种的丧失？在一组实验中，哺乳动物(但不是鸟类或蚂蚁)获得种子的速度将翻一番。在另一组中，在相当均匀的草原上，通过去除小面积的草来增加斑块。将对小型哺乳动物进行普查，并测量它们从环境中清除种子的自然速度。这个为期4年的项目的结果将立即引起基础生态学家的兴趣，作为对一般理论的测试。这些发现也将对科学家制定生物保护战略有价值。

In many environments, the richer the environment, the fewer species it can support. This is true at least in lakes, tropical forest, semi-arid plains and mountainsides, and oceans. It is true of trees and other vegetation, terrestrial mammals, and various kinds of aquatic invertebrates. No general explanation for it has yet been proved. However, preservation of the world's species requires an understanding of the mechanisms which regulates the number of species in natural environments. This research will test two hypotheses in the field. 1) Do other forms of life usurp the resources of a given form as production rises? For example, does the number of mammal species decline because birds and ants take their food? 2) Does the habitat become simpler, costing some specialists their livelihood as production rises? For example, does the variety of architectural forms found among plants diminish, causing the loss of some mammal species? In one set of experiments, the rate at which seeds become available to mammals (but not birds or ants) will be doubled. In another set, in a fairly uniform grassland, the patchiness will be increased by removing small areas of grass. Small mammals will be censused and the natural rate at which they remove seeds from the environment will be measured. Results for this 4-year project will be of immediate interest to basic ecologists as a test of general theory. Findings will also be valuable to scientists developing strategies of bioconservation.