Impacts of selective logging on canopy and ground assemblages of tropical forest butterflies: Implications for sampling

Commercial selective logging is a major cause of habitat disturbance in Southeast Asian rainforests, yet despite much research there is little consensus on impacts of disturbance on biodiversity. There is also little consensus on the most appropriate methods for sampling tropical species, making it difficult to draw general conclusions from published studies. For example, many studies have used butterflies to assess impacts of selective logging but sampling has usually been conducted at ground level and the canopy fauna has often been ignored. In this study, we investigate the importance of sampling in the canopy by using fruit-baited traps to investigate impacts of selective logging on Nymphalid butterflies in primary forest and forest selectively logged 15 years previously in Sabah (Malaysian Borneo). Analysing combined data from canopy (≈25 m above ground level) and ground-level traps showed significantly lower diversity in selectively logged forest. However, this difference was not observed when data from only ground traps were analysed. Primary forest supported a butterfly assemblage comprising species with more restricted geographical ranges, and thus higher conservation value, compared with selectively logged forest. This result was observed regardless of whether or not canopy data were included in this analysis. We conclude that sampling in the canopy is critical when producing species inventories, but of little importance when determining the impacts of selective logging on restricted-range species.