Orchid Island, 92 km off the southeast coast of Taiwan, has the northernmost tropical forests in East Asia. We assessed effects of habitat management by Orchid Island inhabitants, the Yami people, on spider diversity by comparing assemblages collected from the ground to canopy among four habitats (natural forest, cultivated woodland, second growth forest and grasslands) that receive different degrees of disturbance. Species and guild composition did not differ among replicates of habitat but differed significantly among habitats. Variation in spider diversity was inversely correlated with vegetation density. Cultivated woodland subjected to an intermediate level of disturbances had a lower understory vegetation density than natural forest, but higher spider diversity. Neither insect abundance nor biomass varied significantly among habitats suggesting little room for effects of prey availability on spider diversity. It appears that the Yami people maintain high spider diversity on Orchid Island by generating novel habitat types with different vegetation structures and disturbance regimes.