Spider diversity in canopies of Xishuangbanna rainforest (China) indicates an alarming juggernaut effect of rubber plantations

Abstract

We were interested in how forest type and complexity of vegetation influence the diversity of canopy spiders in the rainforest of Xishuangbanna, southwestern China. We sampled spiders by fogging tree canopies in four replicate sites of five different forest types once in the middle of the rainy season, forest types were tropical seasonal rainforest; monsoon forest; mountain rainforest; Aporusa yunnanensis forest; and rubber plantation. From a total of 20 sites and 1000m2 projected area we collected 4999 adult spiders of 472 species. Vegetational structure (number of plant forms, such as herbs, shrubs, trees, epiphytes and lianas), tree coverage, shrub coverage, grass coverage, tree height and elevation characterize the environmental conditions in different types of forest. Species richness and mean abundance differed significantly between rubber plantations and natural habitats. Rubber plantations harbored only 42.6–50% of the spider species in the natural forests, and 63.8% of the species in the A.yunnanensis forests. Spider guild composition also differed among forest types. Sheet-line weavers dominated the spider assemblages in natural forests with complex vegetational structure, such as tropical seasonal rainforests and monsoon forests. In contrast, cursorial hunters dominated forests with a more simple structure, such as rubber plantations and A.yunnanensis forest. These results show that intensive management practices in rubber plantations decrease the complexity of the vegetation and, so, strongly influence the diversity and composition of canopy spider assemblages. A lower intensity of management and the restoration of native vegetation may help balance the opposing needs of economic development and biodiversity conservation in this region.