Assessing the Compatibility of Fuel Treatments, Wildfire Risk, and Conservation of Northern Spotted Owl Habitats and Populations in the Eastern Cascades: A Multi-scale Analysis.

Authors

Martin G. RaphaelFollow
Paul Hessburg, USDA Forest Service
Rebecca Kennedy, USDA Forest Service
John Lehmkuhl, USDA Forest Service
Bruce G. Marcot, USDA Forest Service
Robert Scheller, Portland State University
Peter Singleton, USDA Forest Service
Thomas Spies, USDA Forest Service

Date of this Version

2013

Document Type

Article

Citation

Final Report: JFSP Project 09-1-08-31

Comments

US government work.

Abstract

National Forests in the dry forest provinces on the east-side of the Oregon and Washington Cascades have been managed under the guidelines of local Forest Plans and the Northwest Forest Plan (NWFP), both of which specify large areas of late-successional reserves (LSRs). In contrast, the recently-released USDI Fish and Wildlife Service Revised Recovery Plan (RRP) for the Northern Spotted Owl (NSO) calls for development of dynamic and shifting mosaics in the dry forests, and retention of LSRs in moist forests of eastern Cascades of Oregon and Washington, to address NSO habitat and wildfire concerns. Our objectives in this study were to develop and evaluate several key management approaches intended to reduce fire risk and conserve NSO habitat and to assess the relative merit of alternative management strategies in fire-prone stands and landscapes. We first sought to determine the current area and successional status of east-side forests across eastern Cascade forests in Oregon and Washington. Next, we simulated succession, wildfire, and fuel treatments using a state-and-transition model, LADS. Finally, we translated forest cover types into three levels of NSO habitat suitability (poor, moderate, and good) and applied an NSO population simulation model to investigate response of the NSO to vegetation trajectories over a 100-yr time series. To do so, we developed a spatially explicit, individual-based population model using HexSim software that integrated habitat maps with information on spotted owl population dynamics. We then compared the outcomes of several landscape management scenarios: no restoration management, restoration management under the Northwest Forest Plan reserve network, and several whole-landscape scenarios that vary the area and intensity of treatments without regard for current reserve allocations. All of our simulations assumed a wildfire regime that reflects the past 15 years of fire history, including the potential for large, rare fire events. NSO population changes through time generally tracked changes in total NSO habitat (the combined amount of good and moderate NSO habitat) and showed similar patterns for the Wenatchee analysis area and the Deschutes NSO population scenarios without BDOW displacement. Decadal lambda (rate of population change was approximately stationary (lambda ~1) from simulation years 0 to 30 for most scenarios excepting the large-area, high-intensity treatments, which resulted in decadal NSO population decline (lambdas <1) for those years. NSO population bottlenecks (temporary periods of lower than average population levels) generally occurred in both analysis areas around year 30, after treatments had been applied but before the steep accumulation of good habitat in years 30-50. All of the NSO population modeling scenarios showed a spike in decadal lambda from years 30 to 60 in response to a steep, synchronous increase in the modeled amount of good and moderate habitat. Higher-intensity, larger-area treatment scenarios created short-term NSO habitat and population bottlenecks, but had mixed effects on end-century NSO population sizes. Particularly for the Wenatchee analysis area, we did not find larger ending NSO population sizes from aggressive fuel reduction treatments relative to the No Treatment scenario. The presence of both good and moderate habitat contributed substantially to the suitability of an area for occupancy by a territorial NSO pair based on our analysis of habitat conditions surrounding documented NSO activity centers. Active fuel reduction activities in moderate habitat contributed to substantial short-term (simulation years 0 to 30) population declines under the larger area, higher intensity scenarios. However, our landscape-scale analysis may have failed to detect local benefits of targeted fuel reduction treatments for habitat sustainability and recruitment in specific areas. More refined, finer-scale analysis may reveal more local benefits of fuel reduction treatments for recruiting and maintaining NSO habitat.