SOIL ARTHROPOD ABUNDANCE IN COAST REDWOOD FOREST - EFFECT OF SELECTIVE TIMBER HARVEST

Soil arthropod communities were surveyed and compared in litter layers of selectively harvested and nonharvested forests of coast redwood, S equoia sempervirens, to assess impact of a 15-yr selective timber harv est cycle. Abundance of four guilds (microphytophages, panphytophages, macrophytophages, and predators) were estimated From litter samples t aken from three forest classes: uncut old growth, mature second growth last harvested before 1920, and selectively harvested forest sampled 14 yr after harvest. Microphytophage and panphytophage abundance did n ot vary significantly among Forest classes. Macrophytophages showed si gnificantly higher abundance in selectively harvested forest, whereas predators showed significantly reduced abundance in selectively harves ted forest. Because no significant differences in macrophytophage and predator abundance were found between old growth and mature second gro wth classes, observed differences are attributed to the selective timb er harvest regime. Furthermore, since selectively harvested forest was sampled for arthropods 14 yr after harvest, it appears that the 15-yr cycle is of insufficient duration to allow full recovery of soil arth ropod communities from the effect of selective timber harvest. In addi tion, it is likely that species are at high risk of extinction, based oil the striking observation that an entire order, Diplura, was absent from all samples taken from selectively harvested sites. Possible exp lanations for observed differences in guild abundance and potential im plications for long-term maintenance of soil arthropod diversity are d iscussed.