Pattern or process? Evaluating the peninsula effect as a determinant of species richness in coastal dune forests

摘要: The peninsula effect predicts that the number of species should decline from base a to tip. However, evidence for is ambiguous, as different analytical methods, study taxa, and variations in local habitat or regional climatic conditions influence conclusions on its presence. We address this uncertainty by using two methods investigate three taxa occupy trophic levels: trees, millipedes, birds. surveyed 81 tree quadrants, 102 millipede transects, 152 bird points within 150 km coastal dune forest resemble along northeast coast South Africa. then used spatial (trend surface analyses) non-spatial regressions (generalized linear mixed models) test presence each taxa. also models if climate (temperature precipitation) and/or (water availability associated with topography landscape structural variables) could explain gradients richness. Non-spatial suggest was present all indicated only richness declined Millipede increased near centre peninsula, while Local explained patterns birds but not regardless model type. Our highlights idiosyncrasies effect-conclusions depend taxon studied. might therefore be better suited describe pattern where broader narrow tip, rather than process drives