Sazonalidade da comunidade de macrofauna do solo em um gradiente de degradação de florestas ripárias na Amazônia Oriental

Abstract

Land-use change and rainfall seasonality are considered the main factors that alter the composition, abundance and activity of soil macrofauna in tropical regions. This study aimed to assess the seasonality effect on soil macrofauna along of a gradient of degradation of riparian forests in eastern Amazon. Our study was performed within the watershed of Pepital and Grande 34 rivers in the municipality of Alcântara (MA). The climatic conditions are characterized by well-defined dry and rainy seasons. We established four forest degradation levels in the riparian forest along the watersheds: low (similar to natural forest), medium (secondary forest), high (young secondary forest) and very high (open vegetation and dominated by bare soil). Macrofauna sampling was performed in the dry and rainy seasons by collecting soil monoliths at 0.10 m depth. According to between-classes analysis the seasonality explained 5.0 % of the variance in macrofauna community. There was a reduction in total abundance and also for 11 of the 30 taxa identified along the degradation gradient. The main effects were the reduction of the abundance of soil engineers, saprophagous and predators. The combined of effect seasonality and degradation reduced the total abundance of the community, and the major reduction in the macrofauna was caused by the degradation gradient during the dry season. In this study we identify the Embiidina group as the most sensitive to seasonality, while the Isoptera, Gastropoda, Araneae, Chilopoda and Diplura groups were more affected by degradation. The impact of degradation on the abundance of soil macrofauna community are more severe in the dry season