A PLOT STUDY OF FOREST FLOOR LITTER FROGS, CENTRAL AMAZON, BRAZIL

Abundance and distribution of frogs inhabiting the litter layer of an area of primary lowland rain forest in Central Amazonia were studied over a period of 15 months by sampling 498 plots each 5 m x 5 m. The litter fauna of the area consists of 23 species, but only 12 of these were encountered in the plots, and 84% of the frogs encountered belonged to only six species. Total abundance and diversity within the plot data are strongly seasonal and peak in the late wet season. Both are positively correlated with litter volume and moisture. Most of this variation is due to seasonality of reproduction, as indicated by patterns of occurrence of juveniles of the most abundant species. These results indicate that the plot sampling method does not sample the entire fauna adequately. Since, this technique has been used to study other tropical forest litter herpetolaunas, however, comparison with other studies may be useful. Species diversity of litter frogs appears to be approximately the same in lowland primary forest sites studied, averaging around 20 'regular' species. Abundances, however, vary widely. Central American communities contain 14-15 frogs (100 m)-2, African 9-10, South American 4-6, and South-east Asian 1-2. These differences may be due to differential nutrient availability in forests of different ages and/or on different soils.