Impacts of thinning on diversity of Hymenoptera in pine plantation forest of Sukabumi, West Java, Indonesia

Abstract

Partial cutting technique (thinning) of pine tree to improve pine growth and timber quality causes disturbances to the forest which can affect forest fauna, especially the order Hymenoptera. This study aimed to analyze how the species abundance and richness of Hymenoptera is influenced by thinning in pine plantation forest. The study compared Hymenopteran abundance before and after thinning of the pine forest. Intensity of forest thinning was at 20%. The plot used in this study was cluster plot for forest health and monitoring. The number of plots was 4 plots, which was placed systematically in the thinning area of 7.85 ha. The Hymenopterans caught using 80 pitfall traps before thinning and after thinning. Insects were identified to morphospecies level. Non parametric statistics (Mann-Whitney and Friedman test) were used to analyze the difference in abundance and species richness of Hymenoptera before thinning and after thinning at the significant level of 5%. The number of individual Hymenopterans before thinning was 2,369 individuals, consisting of 3 families, 27 genera and 44 morphospecies. After thinning, the number of individual Hymenoptera was 2,400 individuals, consisting of 4 families, 24 genera and 45 morphospecies. The abundance of Hymenopterans before thinning and after thinning was not significantly different whereas the morphospecies composition of Hymenoptera before thinning and after thinning was significantly different.