Complementary and protection value of a Biosphere Reserve buffer zone for increasing local representativeness of ground-living arthropods

Abstract

Biosphere reserves (BRs) are areas of high biodiversity value that promote conservation and sustainable development. BRs consist of core, buffer, and transition zones. Buffer zones are where human and ecological activities overlap, and are key functional spaces that can have important complementarity value. We test this using ground-living arthropods in the highly biodiverse Kogelberg Biosphere Reserve in South Africa. We use generalized dissimilarity modelling to describe the compositional dissimilarity of assemblages as a function of environmental correlates between pairs of survey sites. Transformed spatial predictors were used as surrogates for biodiversity to assess complementarity. Important correlates of arthropod species turnover were related to mesoclimate, fire history, and geology. Buffer areas had important complementary value. Current habitat transformation across core and buffer zones does not change this, as results were the same when removing all transformed areas from the analyses. Important areas in buffer zones that increased local representativeness coincided with areas of increased intra-annual temperature variability. Orchards in transformed areas also influenced arthropod diversity in adjacent natural vegetation by <1km from orchard edges. This edge effect influenced both core and buffer sites due to the lack of a continuous buffer, indicating that the buffer zone is important for protecting the core. As fire management is an important correlate of arthropod turnover here, the complementary value of the buffer zone can have a strong temporal dimension. Given the important complementary value of the buffer zone, conservation management should not be restricted to core areas only, especially when maximising local representativeness.