Dissertation Research: Is Decomposition in Moist Tropical Forests Phosphorus Limited?

尽管人们普遍认为，磷(P)的有效性对热带森林的生态系统动态有很强的限制，但对这一观点的直接测试很少。此外，大多数研究都集中在P对植物群落的限制上；实际上，没有人提出微生物群落受磷限制的可能性。克利夫兰先生迄今为止的论文研究表明，在哥斯达黎加西南部的低地热带雨林中，碳的分解是有限的，尽管这种限制的程度仍然未知。早期的研究结果表明，尽管磷对微生物过程有明显的限制，但负责有机磷矿化的磷酸酶的产量和活性相对较低。本博士论文改进基金将支持解决以下两个基本问题的实验：1。在潮湿的热带森林中，磷的有效性是否限制了原生碳的分解？和2。在一个有机磷矿化对弥补有效无机磷的不足很重要的地方，磷酸酶的活性是否直接受到另一种元素的可用性的限制？

Despite a widespread belief that phosphorus (P) availability poses a strong constraint on ecosystem dynamics in tropical forests, direct tests of this belief are rare. Furthermore, most studies that have addressed this issue have focused on P limitation to the plant community; virtually none have addressed the possibility that the microbial community is P limited. Mr. Cleveland's dissertation research to date suggests that decomposition of carbon in a lowland tropical rainforest in southwestern Costa Rica is P limited, although the extent of this limitation is still unknown. Early findings have revealed that in spite of the apparent P limitation to microbial processes at this site, the production and activity of phosphatases, enzymes responsible for the mineralization of organic P, are relatively low. This Doctoral Dissertation Improvement Grant will support experiments that address the following two basic questions: 1. Does phosphorus availability limit the decomposition of native carbon in moist tropical forests? and 2. At a site where the mineralization of organic P should be important in offsetting deficiencies in available inorganic P, is phosphatase activity directly limited by the availability of another element?