Joshua S. Halofsky

Climate Change and Land Management in the Rangelands of Central Oregon

Climate change, along with exotic species, disturbances, and land use change, will likely have major impacts on sagebrush steppe ecosystems in the western U.S. over the next century. To effectively manage sagebrush steppe landscapes for long-term goals, managers need information about the interacting impacts of climate change, disturbances and land management on vegetation condition. Using a climate-informed state-and-transition model, we evaluated the potential impacts of climate change on rangeland condition in central Oregon and the effectiveness of multiple management strategies. Under three scenarios of climate change, we projected widespread shifts in potential vegetation types over the twenty-first century, with declining sagebrush steppe and expanding salt desert shrub likely by the end of the century. Many extreme fire years occurred under all climate change scenarios, triggering rapid vegetation shifts. Increasing wildfire under climate change resulted in expansion of exotic grasses but also decreased juniper encroachment relative to projections without climate change. Restoration treatments in warm–dry sagebrush steppe were ineffective in containing exotic grass, but juniper treatments in cool–moist sagebrush steppe substantially reduced the rate of juniper encroachment, particularly when prioritized early in the century. Overall, climate-related shifts dominated future vegetation patterns, making management for improved rangeland condition more difficult. Our approach allows researchers and managers to examine long-term trends and uncertainty in rangeland vegetation condition and test the effectiveness of alternative management actions under projected climate change.

Dry forest resilience varies under simulated climate‐management scenarios in a central Oregon, USA landscape

Determining appropriate actions to create or maintain landscapes resilient to climate change is challenging because of uncertainty associated with potential effects of climate change and their interactions with land management. We used a set of climate-informed state-and-transition models to explore the effects of management and natural disturbances on vegetation composition and structure under different future climates. Models were run for dry forests of central Oregon under a fire suppression scenario (i.e., no management other than the continued suppression of wildfires) and an active management scenario characterized by light to moderate thinning from below and some prescribed fire, planting, and salvage logging. Without climate change, area in dry province forest types remained constant. With climate change, dry mixed-conifer forests increased in area (by an average of 21–26% by 2100), and moist mixed-conifer forests decreased in area (by an average of 36–60% by 2100), under both management scenarios. Average area in dry mixed-conifer forests varied little by management scenario, but potential decreases in the moist mixed-conifer forest were lower with active management. With changing climate in the dry province of central Oregon, our results suggest the likelihood of sustaining current levels of dense, moist mixed-conifer forests with large-diameter, old trees is low (less than a 10% chance) irrespective of management scenario; an opposite trend was observed under no climate change simulations. However, results also suggest active management within the dry and moist mixed-conifer forests that creates less dense forest conditions can increase the persistence of larger-diameter, older trees across the landscape. Owing to projected increases in wildfire, our results also suggest future distributions of tree structures will differ from the present. Overall, our projections indicate proactive management can increase forest resilience and sustain some societal values, particularly in drier forest types. However, opportunities to create more disturbance-adapted systems are finite, all values likely cannot be sustained at current levels, and levels of resilience success will likely vary by dry province forest type. Land managers planning for a future without climate change may be assuming a future that is unlikely to exist.

Divergent trends in ecosystem services under different climate-management futures in a fire-prone forest landscape

While ecosystem services and climate change are often examined independently, quantitative assessments integrating these fields are needed to inform future land management decisions. Using climate-informed state-and-transition simulations, we examined projected trends and tradeoffs for a suite of ecosystem services under four climate change scenarios and two management scenarios (active management emphasizing fuel treatments and no management other than fire suppression) in a fire-prone landscape of dry and moist mixed-conifer forests in central Oregon, USA. Focal ecosystem services included fire potential (regulating service), timber volume (provisioning service), and potential wildlife habitat (supporting service). Projections without climate change suggested active management in dry mixed-conifer forests would create more open forest structures, reduce crown fire potential, and maintain timber stocks, while in moist mixed-conifer forests, active management would reduce crown fire potential but at the expense of timber stocks. When climate change was considered, however, trends in most ecosystem services changed substantially, with large increases in wildfire area predominating broad-scale trends in outputs, regardless of management approach (e.g., strong declines in timber stocks and habitat for closed-forest wildlife species). Active management still had an influence under a changing climate, but as a moderator of the strong climate-driven trends rather than being a principal driver of ecosystem service outputs. These results suggest projections of future ecosystem services that do not consider climate change may result in unrealistic expectations of benefits.

Wildlife Habitat Management

Wildlife biologists have been designing habitat models for over 50 years; however, the use of the Ecosystem Management Decision Support system (EMDS) in association with modeling is a relatively recent addition to the field. EMDS has proven its usefulness to habitat modeling and evaluation through successful application to a number of large landscape (>5000 km2) studies. While EMDS cannot be used to model wildlife populations directly, past efforts have incorporated population data, along with a variety of other indicators. Here, we provide an overview of previous modeling efforts, with an emphasis on the northern spotted owl (Strix occidentalis caurina). We then review applications of EMDS to wildlife modeling, before delving into a case study. In that study, the Washington State Department of Natural Resources (DNR) used EMDS to assess the impacts of alternative forest management strategies on dispersal habitat for spotted owls. We discuss how expert workshops were used to define three separate EMDS models to assess and score patches of foraging, roosting, and movement habitat across a large landscape. We used the habitat scores to develop a dispersal habitat model outside of EMDS, which incorporated graph theory concepts and a variable resistance landscape surface to assess the connectivity of owl dispersal habitat.