Maintaining dense forest habitats for the threatened northern spotted owl (NSO) has proven challenging in seasonally dry, fire-dependent landscapes where low-density conditions were historically dominant and are generally more climate- and disturbance-resilient. To better inform the dual, sometimes-conflicting objectives of species conservation and forest resilience, we developed an approach to evaluate NSO habitat sustainability by: (1) quantifying the structure of high suitability habitat (HSH) associated with NSO using two remotely sensed platforms, (2) estimating current and historical HSH abundance, and (3) identifying HSH locations more likely to persist given current and future forest-zone climate projections and increasing risk of severe wildfire. Tall, closed-canopy conditions effectively comprised the key structural features of HSH, providing a means to map habitat through time. Both historical amounts and contemporary spatial patterns of HSH and other forest and non-forest conditions around occupied NSO sites indicated that HSH and forest resilience goals can be congruent at multiple scales. Independent lines of evidence suggest HSH historically composed similar to 18-24% of the dry and moist mixed-conifer landscape - considerably lower levels than current management goals in many areas. Projected shifts in climate and severe-fire likelihood suggest substantial spatial and temporal shifts where HSH will be sustainable into the future - mainly in currently moist as well as some cold forest types. These findings can inform the potential convergence and trade-offs of species conservation and disturbance resilience goals across local and regional landscapes, based on the inherent capacity of the landscape to support both goals under projected shifts in climate and wildfire.

Hessburg, Paul F.; Charnley, Susan; Wendel, Kendra L.; White, Eric M.; Singleton, Peter H.; Peterson, David W.; Halofsky, Jessica E.; Gray, Andrew N.; Spies, Thomas A.; Flitcroft, Rebecca L.; White, Rachel. 2020. The 1994 Eastside Screens large-tree harvest limit: review of science relevant to forest planning 25 years later. Gen. Tech. Rep. PNW-GTR-990. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 114 p. In 1994, a large-tree harvest standard known as the “21-inch rule” was applied to land and resource management plans of national forests in eastern Oregon and Washington (hereafter, the “east side”) to halt the loss of large, old, live, and dead trees and old forest patches. These trees and forest patches have distinct ecological, economic, and social values, as reflected in widespread fish and wildlife use, public support for protecting them, and commercial interest in harvesting them, thus they have been the topic of much discussion and debate. At the request of regional Forest Service managers, we review the scientific knowledge accrued since implementation of the 21-inch rule and discuss the rule’s role and relevance to forest planning today. Critical to our review are new findings from the social sciences and their integration with new biophysical and ecological science to form a more holistic understanding of forest ecosystems and the values they provide. We examine how human values associated with old trees and old forests are nuanced and evolving and discuss important social and economic changes relevant to large, old trees and old forests that have occurred across the Pacific Northwest in the past three decades. Major advances also have been realized in landscape and fire ecology, climate and carbon science, and wildlife, fishery, and silviculture sciences related to the role and importance of large and old trees in east-side forests. Key findings show that trees of early-seral species that are older than 150 years contribute important ecological values not present in younger large trees. Other findings come from climate change research, landscape assessments, and fire history studies, which have contributed knowledge about the historical and likely future variability in fire frequency and severity in various forest types, landscape dynamics, and how landscape resilience works. Many forests are now homogenized, with conditions no longer resembling those that existed prior to Euro-American settlement. Disturbance regimes have become more severe in many places, causing widespread ripple effects. The area burned by wildfire will continue to increase under climate change, and disturbance regimes will change further, leading to even broader changes in forest structure and species composition. Moderate or severe fires or fuel treatments, coupled with maintenance burning, may be needed to remove local seed sources and competition from undesirable shade-tolerant trees and help some patches of forest better adapt to fire and climate change. Proactive management can help facilitate some transitions, leading to better outcomes for people, forests, and native species.

In 1994, a large-tree harvest standard known as the “21-inch rule” was applied to land and resource management plans of national forests in eastern Oregon and Washington (hereafter, the “east side”) to halt the loss of large, old, live, and dead trees and old forest patches. These trees and forest patches have distinct ecological, economic, and social values, as reflected in widespread fish and wildlife use, public support for protecting them, and commercial interest in harvesting them, thus they have been the topic of much discussion and debate. At the request of regional Forest Service managers, we review the scientific knowledge accrued since implementation of the 21-inch rule and discuss the rule’s role and relevance to forest planning today. Critical to our review are new findings from the social sciences and their integration with new biophysical and ecological science to form a more holistic understanding of forest ecosystems and the values they provide. We examine how human values associated with old trees and old forests are nuanced and evolving and discuss important social and economic changes relevant to large, old trees and old forests that have occurred across the Pacific Northwest in the past three decades. Major advances also have been realized in landscape and fire ecology, climate and carbon science, and wildlife, fishery, and silviculture sciences related to the role and importance of large and old trees in east-side forests. Key findings show that trees of early-seral species that are older than 150 years contribute important ecological values not present in younger large trees. Other findings come from climate change research, landscape assessments, and fire history studies, which have contributed knowledge about the historical and likely future variability in fire frequency and severity in various forest types, landscape dynamics, and how landscape resilience works. Many forests are now homogenized, with conditions no longer resembling those that existed prior to Euro-American settlement. Disturbance regimes have become more severe in many places, causing widespread ripple effects. The area burned by wildfire will continue to increase under climate change, and disturbance regimes will change further, leading to even broader changes in forest structure and species composition. Moderate or severe fires or fuel treatments, coupled with maintenance burning, may be needed to remove local seed sources and competition from undesirable shade-tolerant trees and help some patches of forest better adapt to fire and climate change. Proactive management can help facilitate some transitions, leading to better outcomes for people, forests, and native species.

The worldwide decline of large carnivores is concerning, particularly given the important roles they play in shaping ecosystems and conserving biodiversity. Estimating the capacity of an ecosystem to support a large carnivore population is essential for establishing reasonable and quantifiable recovery goals, determining how population recovery may rely on connectivity, and determining the feasibility of investing limited public resources toward recovery. We present a case study that synthesized advances in habitat selection and spatially-explicit individual-based population modeling, while integrating habitat data, human activities, demographic parameters and complex life histories to estimate grizzly bear carrying capacity in the North Cascades Ecosystem in Washington. Because access management plays such a critical role in wildlife conservation, we also quantified road influence on carrying capacity. Carrying capacity estimatesranged from 83 to 402 female grizzly bears. As expected, larger home ranges resulted in smaller populations and roads decreased habitat effectiveness by over 30%. Because carrying capacity was estimated with a static habitat map, the output is best interpreted as an index of habitat carrying capacity under current conditions. The mid-range scenario results of 139 females, or a total population of 278 bears, represented the most plausible scenario for this ecosystem. Grizzly bear distribution generally corresponded to areas with higher quality habitat and less road influence near the central region of the ecosystem. Our results reaffirm the North Cascades Ecosystem's capacity to support a robust grizzly bear population. Our approach, however, can assist managers anywhere ecosystem-specific information is limited. This approach may be useful to land and wildlife managers as they consider grizzly bear population recovery objectives and make important decisions relative to the conservation of wildlife populations worldwide.

Fire-prone landscapes present many challenges for both managers and policy makers in developing adaptive behaviors and institutions. We used a coupled human and natural systems framework and an agent-based landscape model to examine how alternative management scenarios affect fire and ecosystem services metrics in a fire-prone multiownership landscape in the eastern Cascades of Oregon. Our model incorporated existing models of vegetation succession and fire spread and information from original empirical studies of landowner decision making. Our findings indicate that alternative management strategies can have variable effects on landscape outcomes over 50 years for fire, socioeconomic, and ecosystem services metrics. For example, scenarios with federal restoration treatments had slightly less high-severity fire than a scenario without treatment; exposure of homes in the wildland-urban interface to fire was also slightly less with restoration treatments compared to no management. Treatments appeared to be more effective at reducing high-severity fire in years with more fire than in years with less fire. Under the current management scenario, timber production could be maintained for at least 50 years on federal lands. Under an accelerated restoration scenario, timber production fell because of a shortage of areas meeting current stand structure treatment targets. Trade-offs between restoration outcomes (e.g., open forests with large fire-resistant trees) and habitat for species that require dense older forests were evident. For example, the proportional area of nesting habitat for northern spotted owl (Strix occidentalis) was somewhat less after 50 years under the restoration scenarios than under no management. However, the amount of resilient older forest structure and habitat for white-headed woodpecker (Leuconotopicus albolarvatus) was higher after 50 years under active management. More carbon was stored on this landscape without management than with management, despite the occurrence of high-severity wildfire. Our results and further applications of the model could be used in collaborative settings to facilitate discussion and development of policies and practices for fire-prone landscapes.

Sensitivity analysisdetermination of how prediction variables affect response variablesof individual-based models (IBMs) are few but important to the interpretation of model output. We present sensitivity analysis of a spatially explicit IBM (HexSim) of a threatened species, the Northern Spotted Owl (NSO; Strix occidentalis caurina) in Washington, USA. We explored sensitivity to HexSim variables representing habitat quality, movement, dispersal, and model architecture; previous NSO studies have well established sensitivity of model output to vital rate variation. We developed normative (expected) model settings from field studies, and then varied the values of 1 input parameter at a time by +/- 10% and +/- 50% of their normative values to determine influence on response variables of population size and trend. We determined time to population equilibration and dynamics of populations above and below carrying capacity. Recovery time from small population size to carrying capacity greatly exceeded decay time from an overpopulated condition, suggesting lag time required to repopulate newly available habitat. Response variables were most sensitive to input parameters of habitat quality which are well-studied for this species and controllable by management. HexSim thus seems useful for evaluating potential NSO population responses to landscape patterns for which good empirical information is available.

Competitive interactions with Barred Owls (Strix varia) are an important factor contributing to the decline of the Northern Spotted Owl (Strix occidentalis caurina) population. Understanding the degree of similarity in fine-scale habitat associations for Spotted Owls and Barred Owls will help land managers evaluate whether there are specific vegetation conditions that could favor Spotted Owls over Barred Owls. From March 2004 to September 2006, I tracked 14 radio-tagged Barred Owls in the Okanogan-Wenatchee National Forest in the eastern Cascade Range, Washington. I analyzed forest structure characteristics from 170 plots sampled within areas used by the radio-tagged owls. I identified three forest types present within the Barred Owl home ranges, including: (1) open ponderosa pine (Pinus ponderosa), (2) simple-structure Douglas-fir (Pseudotsuga menziesii), and (3) complex-structure grand fir (Abies grandis). I compared individual forest structure characteristics and the three forest types to the intensity of Barred Owl use based on repeated measures of seasonal utilization distribution values at each plot using hierarchical mixed-effects models. Intensity of Barred Owl use during the breeding season was higher in areas with greater abundance of grand fir trees, taller and more diverse tree heights, more total trees per ha, more trees 12.7-22.9 cm dbh, more tree canopy >4.9 m, and less ground-cover vegetation <0.6 m. During the nonbreeding season, intensity of Barred Owl use was higher in areas with more trees 12.7-22.9 cm dbh, more total trees per ha, gentle slopes, and increased tree species diversity. Barred Owls used the structurally diverse grand fir forest type more intensively than the other two types during the breeding season. Intensity of use did not differ across the types during the nonbreeding season. Forest structure characteristics used by Barred Owls in this study were within the range of conditions reported to be used by Spotted Owls in the eastern Cascade Range.

The dual threats of habitat fragmentation and climate change have led to a proliferation of approaches for connectivity conservation planning. Corridor analyses have traditionally taken a focal species approach, but the landscape “naturalness” approach of modeling connectivity among areas of low human modification has gained popularity as a less analytically intensive alternative.

Context More than a century of forest and fire management of Inland Pacific landscapes has transformed their successional and disturbance dynamics. Regional connectivity of many terrestrial and aquatic habitats is fragmented, flows of some ecological and physical processes have been altered in space and time, and the frequency, size and intensity of many disturbances that configure these habitats have been altered. Current efforts to address these impacts yield a small footprint in comparison to wildfires and insect outbreaks. Moreover, many current projects emphasize thinning and fuels reduction within individual forest stands, while overlooking large-scale habitat connectivity and disturbance flow issues.Methods We provide a framework for landscape restoration, offering seven principles. We discuss their implication for management, and illustrate their application with examples.Results Historical forests were spatially heterogeneous at multiple scales. Heterogeneity was the result of variability and interactions among native ecological patterns and processes, including successional and disturbance processes regulated by climatic and topographic drivers. Native flora and fauna were adapted to these conditions, which conferred a measure of resilience to variability in climate and recurrent contagious disturbances.Conclusions To restore key characteristics of this resilience to current landscapes, planning and management are needed at ecoregion, local landscape, successional patch, and tree neighborhood scales. Restoration that works effectively across ownerships and allocations will require active thinking about landscapes as socio-ecological systems that provide services to people within the finite capacities of ecosystems. We focus attention on landscape-level prescriptions as foundational to restoration planning and execution.

Land managers in the Pacific Northwest have reported a need for updated scientific information on the ecology and management of mixed-conifer forests east of the Cascade Range in Oregon and Washington. Of particular concern are the moist mixed-conifer forests, which have become drought-stressed and vulnerable to high-severity fire after decades of human disturbances and climate warming. This synthesis responds to this need. We present a compilation of existing research across multiple natural resource issues, including disturbance regimes, the legacy effects of past management actions, wildlife habitat, watershed health, restoration concepts from a landscape perspective, and social and policy concerns. We provide considerations for management, while also emphasizing the importance of local knowledge when applying this information at the local and regional level.

Provision of forage for wild and domestic ungulates, and the associated impacts of their herbivory, are contentious issues for wildland management in western North America. We quantified the composition, above-ground net production (ANP), and utilization of herbaceous and shrub vegetation in five non-forest and seven forest cover types across the core spring-summer-fall range of the Yakima elk herd in the eastern Washington Cascade Range. We randomly sampled each cover type along three elevational transects during a two-year period. Riparian/meadow was the most productive cover type (2,752 kg ha(-1) ANP). High-productivity forest at low to high elevations produced 900-1200 kg ha(-1) ANP. High-elevation forest and grassland, shrubland, and shrub-steppe produced 600-700 kg ha(-1) ANP. The low-productivity forest cover types and parkland produced 100-400 kg ha(-1) ANP. Utilization of forbs, grasses, and shrubs combined averaged 47% of ANP across all cover types, ranging from 26% in high-elevation forest to 63% in shrub-steppe. Grasses and forbs were equally utilized at about 57% of ANP, whereas shrubs were utilized at only 4% of ANP. Twenty-two of 55 shrub species accounted for the majority of shrub productivity and showed little to no long-term browsing; but, several shrub species were moderately to severely hedged. Moderate to high levels of ungulate utilization indicate potentially strong impacts of ungulate herbivory on pattern and process in eastern Cascades forests. Dry forest restoration management to reduce fuel loads and restore resiliency to disturbance likely will increase forage for ungulates, especially in closed-canopy true fir and Douglas-fir stands.

As the climate changes, human land use may impede species from tracking areas with suitable climates. Maintaining connectivity between areas of different temperatures could allow organisms to move along temperature gradients and allow species to continue to occupy the same temperature space as the climate warms. We used a coarse‐filter approach to identify broad corridors for movement between areas where human influence is low while simultaneously routing the corridors along present‐day spatial gradients of temperature. We modified a cost–distance algorithm to model these corridors and tested the model with data on current land‐use and climate patterns in the Pacific Northwest of the United States. The resulting maps identified a network of patches and corridors across which species may move as climates change. The corridors are likely to be robust to uncertainty in the magnitude and direction of future climate change because they are derived from gradients and land‐use patterns. The assumptions we applied in our model simplified the stability of temperature gradients and species responses to climate change and land use, but the model is flexible enough to be tailored to specific regions by incorporating other climate variables or movement costs. When used at appropriate resolutions, our approach may be of value to local, regional, and continental conservation initiatives seeking to promote species movements in a changing climate.

Non-native fish and Bullfrogs (Lithobates catesbeianus) are frequently cited as contributing to the decline of ranid frogs in the western United States. Because of this, we hypothesized that non-native species, habitat, or a combination relate to the probability of local extinction for Northern Red-legged Frogs (Rana aurora) in western Oregon. In the first 5 y of an ongoing study, we found no support for the non-native species hypothesis. Instead, the probability of local extinction decreased with the extent of emergent vegetation and riparian forest.

ABSTRACT Competition with barred owls (Strix varia varia) is an important factor contributing to the continued decline of threatened northern spotted owl (Strix occidentalis caurina) populations in the Pacific Northwest, USA, but basic information on habitat selection and space use patterns of barred owls is lacking for much of the region. We investigated space use and habitat selection by tracking radiotagged barred owls in the Eastern Cascade Range of Washington, USA, from 2004 to 2006. We surveyed for barred owls across the 309‐km2 study area and confirmed presence of barred owl pairs at 21 sites. We collected movement data on 14 barred owls from 12 sites. Mean annual 95% fixed‐kernel home‐range size was 194 ha for females (n = 4, SD = 70) and 288 ha for males (n = 5, SD = 114). Home ranges were located more frequently than expected in areas with low topographic position, gentle slopes, large overstory tree‐crown diameter, high normalized difference vegetation index (NDVI), overstory tree canopy closure >72%, and a moderate amount of solar insolation. Within home ranges, areas that had large tree‐crown diameters, low topographic positions, and gentle slopes were used more frequently than expected. The resource selection function we developed for barred owls in our study area indicated that barred owls used areas with the combination of low values for topographic position and slope and higher values for NDVI, solar insolation, and an interaction term for canopy closure and tree‐crown diameter. In comparison to published information on northern spotted owls, barred owls used areas with similar canopy closure and tree size classes, but barred owl home ranges were much smaller and more concentrated on gentler slopes in valley bottoms. This information may contribute to the development of management practices that maintain forest characteristics appropriate for spotted owl habitat and prey in areas where spotted owls are least likely to be excluded by territorial barred owls in the Eastern Cascades of Washington.

Summary Effective decision‐making in environmental management requires the consideration of multiple objectives that may conflict. Common optimization methods use weights on the multiple objectives to aggregate them into a single value, neglecting valuable insight into the relationships among the objectives in the management problem. We present a multi‐objective optimization procedure that approximates the non‐dominated Pareto frontier without the use of weightings, allowing for visualization of the trade‐offs among objectives. The non‐dominated Pareto frontier is approximated by the simultaneous optimization of a vector objective function; two vector objective functions are defined as non‐dominated if improvement with respect to one objective is at the detriment of another objective. We demonstrate the method with a case study for the optimum distribution of forest fuels treatments that reduce the impact of fire on a forest. The multiple objectives are to protect habitat of an endangered species, protect late successional forest reserves and minimize the total area treated. In the comparison of three optimization searches, the number of non‐dominated solutions increases with the dimensions of the objective space, but with only two objectives the search is ineffective in minimizing fire impact in the different landscape types. Key challenges include the extensive computation time required to approximate the non‐dominated set, and reducing the number of solutions that are analysed in detail. Synthesis and applications . The multi‐objective optimization program presented can be adapted to other environmental management problems, and easily incorporates a wide range of quantifiable objectives. This tool provides decision‐makers with a set of alternatives that estimates the full range of trade‐offs among multiple objectives and provides a common ground from which dialogue can come to an informed compromise and decision in environmental management problems.