Community structure of vascular plants, arthropods, amphibians, and mollusks in managed forests of the Pacific Northwest (USA)

Increasing global demands on forest resources are driving large-scale shifts toward plantation forestry. Simultaneously balancing resource extraction and ecological sustainability objectives in plantation forests requires the incorporation of innovative silvicultural strategies such as leave islands (green-tree retention clusters). Our primary research goal was to determine how leave islands provide refugia for low-mobility, ecologically sensitive species in managed forests of the Pacifi c Northwest, USA. We examined patterns in vascular plant, arthropod, amphibian, and mollusk assemblages across fi ve types of forest sampling units: unthinned forest (approximately 600 trees per hectare [tph]), thinned forests (200 tph), and leave islands of three sizes (0.1-, 0.2-, and 0.4- ha]) embedded in the thinned forest. Our objectives were to examine gradients in community associations to measured environmental variables, to describe diff erences in communities among the fi ve types of forest, and to identify species indicative of each type of forest.