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

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

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?