COS 178-4 - Modeling future shifts in species habitat, carbon storage, and timber production in the Elliott State Research Forest under a Triad management system, windstorms, wildfire, and climate change.

Abstract: Our project supports management planning for the newly designated Elliott State Research Forest (ESRF), now the largest research forest in North America, which extends over 33,000 hectares of the Southern Oregon Coast Range. Oregon State University plans to implement a Triad management system, with subwatersheds allocated to one of four treatments comprising different proportional combinations of the following three stand-scale silvicultural strategies: 1) reserves, where the focus is on conservation of habitat and species with minimal active management; 2) intensive management, where maximizing timber production is the primary objective; or 3) extensive management (or ecological forestry), which attempts to balance timber production with broader ecological objectives, such as development of structural complexity. However, it is unknown how this management regime combined with wind and fire disturbances will affect key ecosystem services. To answer this, we estimated changes in long-term forest and carbon dynamics under the proposed harvest design, windstorms, wildfire, and climate change using LANDIS-II, a spatially explicit, process-based forest simulation model. Our study landscape, modeled at a high resolution (30m x 30m), includes the entire ESRF and a surrounding buffer to allow fires to spread into the ESRF. Our initial results highlight the importance of the integrated effects of wind, fire, and management in reducing average biomass by 76% over an 85-year period, compared to only 23% in the absence of natural disturbances. The average stand age was reduced by 52% under the integrated effects of harvesting, fire, and wind disturbances, but increased by 27% under only harvesting. Unexpectedly, stands with intensive management stored significantly less carbon under just wind or fire, but when both fire and wind were simulated together, carbon storage under the reserve, extensive, and intensive treatments converged by the end of the century. These results indicate the importance of wind as a driver of mortality in mid- to late-successional Coast Range forests, the need for forest managers to consider how management practices interact with natural disturbances, and the potential inability of extensive treatments to store more carbon than intensive treatments under interacting disturbances. This project presents a novel opportunity to explore the ecological and economic impacts of different management scenarios on a newly developed research forest under windstorms, wildfire, and climate change.