Towards sustainable commercial moss harvest in the Pacific Northwest of North America.

摘要

The Pacific Northwest is the main source of commercially harvested forest moss in North America, but management guidelines have only included this nontimber forest product for ca. 15 years and research on sustainable harvest practices is barely a decade old. This review summarizes the results of recent research, identifies future research needs, and proposes guidelines for the sustainable management of tree moss (a mixture of mosses and liverworts). The epiphytic species most affected by harvest are Isothecium myosuroides, Neckera douglasii, and Porella navicularis, but dozens of taxa are thought to be impacted. Harvest impacts include reductions in biomass and cover and changes in relative species composition, but it is too early to tell if the species composition will return to pre-harvest conditions. Biomass recovery is slow and estimated rotation periods are 15-25 years. Inventory estimates are still lacking, but harvestable quantities of epiphytic moss are most abundant in low elevation and riparian areas and absent in stands that are very dark and/or lack hardwood tree and shrub species (e.g., <70-year-old Douglas-fir (Pseudotsuga menziesii) plantations). Future research should focus on locating unimpacted reference sites and evaluating the ecosystem functions provided by harvestable moss mats, including the provision of habitat and nutrient and water cycling. Management recommendations include prohibiting commercial moss harvest in forests managed toward old-growth condition, obtaining region-specific estimates of resource inventory and recovery rates, and rotating areas open for moss harvest to allow sufficient recovery between harvest entries..