EDGE EFFECTS IN TROPICAL FOREST FRAGMENTS - APPLICATION OF A MODEL FOR THE DESIGN OF NATURE-RESERVES

There have been few quantitative studies of edge effects in tropical rainforest fragments. I used physiognomic, edaphic, and floristic data from 52 900-m2 plots to describe edge effects in such fragments in NE Queensland, Australia. Relative to unfragmented forest, forest fragments ranging from 1.4 to 590 ha in area had higher canopy and subcanopy damage and exceptional abundances of heavy lianas, climbing rattans Calamus spp., and other disturbance-adapted plants (Dendrocnide spp., Solanum spp.). Elevated forest disturbance was evident up to 500 m inside fragment margins, although the most striking changes occurred within 200 m of edges. Application of these data with a mathematical 'Core-Area Model' suggested that isolated nature reserves in NE Queensland must exceed 2000-4000 ha, depending on reserve shape, to ensure that > 50% of the reserve remains unaffected by induced forest.