Our time will come: Is anuran community structure related to crop age?

An ongoing controversy involves the debate about the effects of man-made land transformation on freshwater biodiversity. It has been suggested that agricultural areas provide habitats for many species of amphibians, but crop age may affect richness and community structure. In such modified landscapes, a nested structure has been commonly detected, although community structure may be season specific and guild specific. Here, we determined detectability associated with site-specific and survey-specific variables and examined nestedness patterns in anuran communities in natural areas and rice fields with different crop ages (10 and 20 years) in southern Brazil. We studied whether nestedness was associated with time since cultivation and whether these patterns were similar across guilds in these areas. Anuran detectability was related only with time after sunset. Community composition varied between crop ages. Aquatic and arboreal species were associated with native areas and showed a nested pattern. Fossorial species did not show significant nestedness. Our results showed that factors associated with crop age may affect guilds in different ways. These effects seem to be related to individual traits of species (habitat preferences, reproductive modes, plasticity). Incorporating species traits may enhance conservation strategies in agroecosystems.