Diversity of canopy spiders (Araneae) assemblages along a transformation gradient in Jambi Province, Indonesia

Arthropod assemblages respond quickly to habitat disturbance and are thus a reliable and often-used indicator of environmental change. Spiders, in particular, are frequently used to assess environmental change in terms of habitat type, habitat structure, wind and temperature exposure. Showing pronounced responses to changes in biotic and abiotic parameters on small scales, spider assemblages show dramatic changes to landscape level conversions of natural habitats to agricultural land. In Indonesia, where large areas of natural lowland rainforest have been and still are converted to agricultural systems such as rubber and oil palm, changes in biodiversity and community composition of arboreal spiders are thus going to be very pronounced. Since spiders are top predators in the invertebrate food web, they have sophisticated effects on agricultural pests and the decomposer system. In turn, spiders are preyed upon by a vast range of birds, reptiles, amphibians, fish and invertebrate parasitoids. Thus, changes in land-use from lowland rainforest to rubber and oil palm plantations are not only going to affect diversity and community compositions of spiders alone, but will entail cascading effects through the entire food web. This, in turn, is likely to have dramatic effects on the ecosystem functions and services of entire agricultural ecosystems. In the proposed research, I will thus study the cascading impact of rainforest conversion on ecosystem services in jungle rubber as well as plantations of oil palm and rubber by focusing on arboreal canopy spider assemblages.