Effects of thinning on spider diversity
in an East Asian subtropical plantation forest. Zoological Studies 50(6): 705-717. Studies examining the effects
of forest management on biodiversity in Asia are scarce and conducted mostly in temperate areas. In this study,
the effects of the management on the biodiversity of a subtropical plantation forest were assessed by comparing
the composition of spiders in Chamaecyparis formosensis plantations located in central Taiwan that received
different degrees of thinning. Sampling plots were established in C. formosensis plantation stands receiving
no, moderate, and heavy thinning treatments and a nearby natural broadleaf forest. The responses of spider
communities in different strata of the plantation forests to thinning treatments varied. Heavy thinning treatment
generated lower diversity indices in ground spiders and higher abundances in canopy spiders. Sampling plots
in plantation stands receiving various thinning treatments differed in the compositions of ground, understory,
and canopy spiders. Such composition variations resulted from abundance changes of ground weavers on the
ground and orb weavers in the understory layer, which in turn seemed to be generated by reduced understory
vegetation complexity due to the thinning treatments. Results of this study show that although thinning practices
do not increase species richness in a subtropical C. formosensis plantation, they can generate alterations
in understory vegetation structures which can lead to increased habitat heterogeneity and spider diversity in
plantation forests.
