Does neutral theory explain community composition in the Guiana shield forests

摘要: Recent years have seen a fierce debate about the causes of beta-diversity, change in species composition over landscapes, tropical rainforests. The introduction neutral models has spurred this debate, by assuming that changes randomly landscapes with dispersal limitation as driving ecological process. In study interaction between local and regional diversity trees is investigated. We inventoried 61 1-ha plots forests on brown white sands, bauxite mountains Guyana Suriname. These data combined earlier led to first biogeographical level involving 156 forest ranging from Venezuela French Guiana. Forest changed dramatically types, at geographical distances. general, followed geological patterns Guianas. Differences plant attributes groups revealed spectrum covariation. On one end high dominance large seeds dry fruits was wood densities several types. other smaller fleshy relatively low community averaged density. This could reflect different colonizing strategies an effect potential dispersers. With neutral-like dynamical models, hypotheses sand were evaluated. Forests sands draw their pools. provide strong evidence asymmetric environmental filtering lower (possibly due size area) influence found compared neighboring forests. White not necessarily more limited than Still within apparent abundance occurred along Thus, we showed gradient beta-diversity occur under similar climatic soil conditions. conservation value terms tree three Northeastern Suriname, evaluated placing 23 plateaus, slopes, lowlands. are all destined for open-pit mining aluminum ore, may constitute rare endangered landscape type. Habitat type (e.g. plateaus) explained floristic similarity distance. plateaus also had highest alpha-diversity currently However, partly random lowlands, each its own specific composition. Guianas show evident differences responses composition, yielding little support view. Most caused small sets common dominate forests, especially where low. Striking biogeograpical rainforests however remain unexplained (current)