Edge effects on litterfall mass and nutrient concentrations in forest fragments in central Amazonia

Forest edges bordering on pasture were created by cutting and burning the s urrounding Amazonian lowland rain forest in the dry season (June) of 1990. Litterfall was measured for 3.5 y along transects 10, 50, 100 and 250-m int o the forest from the forest edge. Litterfall along the 10-m transects incr eased by up to 2.5 times that on spatial controls (250-m transects) in the dry season in which the edge was created. In the second dry season after ed ge creation litterfall at 10-m was lower than on controls, after which it r eturned to control rates in the second wet season, 1.5 y after edge creatio n. Litterfall 50-m into the forest was less affected; there was a smaller r ise in the dry season in which the edge was cut, and no significant effects after that. At 100-m there was no effect of edge creation on litterfall. P hosphorus concentrations in litterfall were elevated along 10-m transects, 10-12 wk after edge creation, possibly because of reduced retranslocation p rior to abscission. The changes in litterfall described here are inextricab ly linked to the biomass collapse, which occurs near forest-fragment edges in the same area.