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构成了强烈的制约，但对这一观点的直接测试很少。此外，解决这个问题的大多数研究都集中在植物群落的磷限制上，几乎没有研究到微生物群落受磷限制的可能性。到目前为止，克利夫兰的论文研究表明，哥斯达黎加西南部低地热带雨林中碳的分解受到磷的限制，尽管这种限制的程度尚不清楚。早期的研究结果表明，尽管磷对该地点的微生物过程有明显的限制，但负责有机磷矿化的酶-磷酸酶的产量和活性相对较低。这项博士论文改进拨款将支持解决以下两个基本问题的实验：1.磷的可用性是否限制了潮湿热带森林中天然碳的分解？2.在一个有机磷矿化对于弥补有效无机磷不足的地方，磷酸酶活性是否直接受到另一种元素的有效性的限制？

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?