Farming practice affects rice field animal biota during cultivation but not fallow periods in Taiwan

Abstract

AbstractRice is one of the most important staple foods in the world, with irrigated rice paddies largely converted from natural wetlands. The effectiveness of rice fields in preserving species depends partially on management practices, including the usage of pesticides. Previous studies have focused predominantly on the cultivation period, leaving the potential effects of soil pesticide residues on organisms during the fallow periods underexplored. Other animals, such as waterbirds, also rely on aquatic invertebrates in flooded fallow fields for their survival. We investigated vertebrates and macroinvertebrates during cultivation and fallow periods in organic and conventional rice fields in Taiwan. The association of environmental factors with terrestrial and aquatic organisms was also analyzed. In total, 32,880 individuals from 144 invertebrate families and 381 individuals from 15 vertebrate families were recorded after nine samplings each in six organic and six conventional rice fields. The family richness and abundance of all invertebrates were higher in organic than in conventional fields during the cultivation period but were similar in fields under either agricultural practice during the fallow period. The differences in richness and abundance of terrestrial invertebrates between the two practices increased with progression of rice cultivation, while there was no difference in abundance of aquatic invertebrates during the fallow period. The richness and abundance of fish, amphibians, reptiles, birds, and migratory waterbirds were not statistically different between the two practices. Our study suggested accumulative effects of pesticides on suppressing terrestrial and aquatic invertebrates during the cultivation period, but no negative effects of soil pesticide residues on aquatic invertebrates during the fallow period. This comprehensive study provided a holistic picture of macroinvertebrate and vertebrate fauna, as well as the potential ramifications of pesticide usage, in a representative Southeast Asian rice paddy ecosystem. Future studies should compare rice fields with natural wetlands to better assess how to capitalize on agroecosystems for biodiversity conservation.