Phytophagous scarabaeid diversity in Swidden cultivation landscapes in Sarawak, Malaysia

In Southeast Asia, swidden cultivation is one of the most important land uses, as it forms and maintains complex mosaics of fallows at various stages in the area. To understand the roles of such a mosaic landscape for biodiversity conservation, we compared the species diversity of phytophagous scarabaeids collected by light trapping among 20 study plots in the following six forest types in Sarawak, Malaysia: primary forest, isolated primary forests, rubber gardens, old fallows, young fallows, and new fallows. Estimated species richness did not significantly differ among the forest types. In contrast, evenness values of new fallows were remarkably lower than those of the other forest types. In addition, species composition could be classified into two groups: new fallows and other forests. These results suggest that rubber gardens and fallows at various stages, with the exception of new fallows, tend to maintain phytophagous scarabaeid diversity at the level found in primary forests or at least in isolated primary forests. These findings highlight the roles of complex mosaic landscapes composed of primary forests and fallows formed in the process of swidden cultivation in recovering and maintaining phytophagous scarabaeid diversity in Southeast Asian tropical landscapes.