Published online by Cambridge University Press: 10 July 2009
The effect of the red land crab (Gecarcinus lateralis) on leaf litter biomass and nutrient transformation was investigated in a semi-deciduous tropical forest on coastal dunes using access and exclusion plots observed for six months. Crabs were in burrows during drought, but began foraging immediately after rainfall. Crabs accelerated litter disappearance significantly during the wet season at one site located beneath Brosimum alicastrum, but had no effect beneath a nearby Enterolobium cyclocarpum. The difference is tentatively attributed to small leaflet size in the latter species which crabs were unable to handle and consume. At both sites, litter in exdosures had approximately doubled by the end of the ensuing dry season. At the Brosimum site it is attributed to sporadic crab detritivory occurring after dry seasonal rains. At the Enterolobium site it is attributed to preferential retention of litter in the cxclosures during strong dry season winds. The nutrient content of litter exposed to, or protected from, crabs was not significantly different at either site and differences in litter nutrient pools reflected differences in litter biomass. Accelerated nutrient mineralization due to crab detritivory was concentrated early in the wet season before leaching began from the soils, and it is suggested that this altered seasonal pattern of mineralization may reduce the loss of nutrients from the site in percolating water.