Does intensification of the rice cultivation cycle influence anuran diversity in rice fields?
The reduction in the amount of fallow time in rice production has occurred in the last years to increase the grain production and to sustain the global market. Some studies have shown environmental problems with reduced fallow time and it could influence negatively the pond anuran diversity. The present study tested three hypotheses: (1) amphibian richness and abundance will be greater in natural areas than rice fields; (2) rice fields with a fallow period will have greater amphibian richness and abundance than fields without this period; and (3) changes in the species composition between natural ponds and rice fields with and without a fallow period will be determined by community nestedness over the agricultural intensification gradient—natural ponds (no impact), fields with fallow period (medium impact) and fields without fallow period (greatest impact). Anurans were sampled from six rice fields cultivated under different levels of agricultural intensification (three fields with and three fields without a fallow season), and three natural ponds in southern Brazil. Although richness did not vary significantly between fields with and without fallow periods, there was a strong tendency in the results for the anuran community in the fields with fallow to be richer than that in the fields without fallow. Additionally, it is important to emphasize that the species composition of the fields with fallow were richer than the species composition of fields without fallow. Therefore, allowing the land to rest could be an important practice for the amphibian community, and rice farmers should manage some parcels of land in the agricultural matrix with resting practices in order to minimize the negative effects of rice production expansion on aquatic biodiversity in natural wetlands.