Information in this short course summarizes the state-of-the science for natural resource managers and decisionmakers regarding climate variability, change, climate projections, and ecological and management responses to climate variability. The information and talks included were produced from a July 2008 workshop at the H.J. Andrews Experimental Forest that brought together key U.S. Forest Service and U.S. Geological Survey scientists, and a select group of pioneering resource managers who served as reviewers and discussants.
Presentations by Connie Millar, Philip Mote, Nate Mantua, and Ron Neilson set the stage for the course with background information regarding the nature of past climates, climate variability and future projections of climate and ecological response. First, Millar highlights some of the natural climate mechanisms that oscillate at multiple and nested temporal scales and also presents some mechanisms by which plant communities have adapted to historical changes in climate. Mote provides background information for understanding current and future climates and impacts at global, continental, and regional scales. He notes that human influence on climate is starting to strongly emerge from the noise of year-to-year variation. For example, increases in annual temperatures have already been documented. Mantua describes the pervasive changes to the hydrologic cycle that are occurring and some of the implications to ecosystems and communities in coming decades. Neilson provides information about potential vegetation distribution in the West using dynamic vegetation models and downscaled climate data. He echoes Millar in noting that management should focus on desired future ecosystem function rather than using concepts such as historical range of variability and offers some suggestions for improving ecosystem resilience.
The next four presentations by Linda Joyce, Dave Peterson, Mike Ryan and Boone Kauffman present information about the ecological consequences of climate change. Joyce lists numerous observed responses of plants and animals to climate change in the West, noting earlier greenup of vegetation in the spring, earlier onset of snowmelt, changes in plant phenology, shifts in animal species distributions, migration patterns, breeding, and earlier end of hibernation. Peterson describes the concept of stress complexes in forests: combinations of biotic and abiotic stresses that compromise the vigor and ultimate sustainability of forest ecosystems. Ryan’s presentation focuses on carbon and the carbon cycle. He notes that U.S. forests annually store 313 million metric tons of carbon, offsetting about 20 percent of U.S. fossil fuel carbon output. Kauffman discusses the importance of tropical ecosystems in the global carbon cycle, their vulnerability to climate change, some current research occurring in the Pacific islands that will be of use in global change research and prediction, and actions that can be taken to mitigate climate change effects in these environments.
The last six short-course presentations revolve around management responses to climate variability. Linda Joyce outlines the purpose of the Forest Service Renewable Resource Assessment with background on the Forest and Rangeland Renewable Resources Planning Act (RPA) and the requirement that the RPA assessment include the analysis of climate change impacts on forest and rangeland resources and identify forestry opportunities for mitigation. Jill Baron argues that successful adaptation of natural resource management to climate change begins by identifying resources and processes at risk, defining thresholds and reference conditions, establishing monitoring and assessment programs, and engaging in management actions that increase the adaptive capacity and ecological resilience of these resources. As climate change progresses, thresholds of resilience will be passed, increasing the importance of addressing uncertainty in planning and management. Connie Millar reiterates the importance of addressing uncertainty and offers a conceptual framework for managing forested ecosystems under assumptions that future environments will be different from present while acknowledging that we cannot be certain about the specifics of change. Dave Peterson presents lessons learned from science-management partnerships on the Olympic and Tahoe National Forests in some initial efforts to develop adaptation options for specific national forests.
Scott Fitzwilliams provides a U.S. Forest Service line officer’s perspective on climate change and forest management. He notes that although discussions associated with climate change are much more robust than they were several years ago, many managers are unsure about where to begin integrating climate change into natural resource planning and offers some suggestions. Mark Nechodom discusses a stewardship project from the Mendocino National Forest that provided an opportunity to measure carbon benefits from forest management. The project tracks changes in forest carbon stocks from to implementation of hazardous fuel reduction prescriptions, and measures benefits of offsetting fossil fuel emissions by using a portion of harvested material for biomass electricity generation. Pete Bisson presents some of the implications of climate change on western fishes and approaches to adapting through good watershed and riparian management.
A key overriding theme regarding forest management and adaptation is that the future will not mirror the past and that targets focused on the past, particularly those that mimic past vegetation structure, are inappropriate. Current research predicts a warmer future, with earlier onset of spring snowmelt, less snowpack in the mountainous West, and different disturbance regimes. Although the future will not mirror the past, scientists also point out that it is critical to understand past conditions and processes, change thresholds, and species’ mechanisms for adapting to these processes, particularly when very long timeframes are used. The key will be to use this information to glean insights for obtaining desired future ecosystem function.
Another common theme was the need for management actions that increase the adaptive capacity and ecological resilience of the Nation’s natural resources. Resource managers must be willing and empowered to proceed in face of inherent uncertainty when making management decisions. This uncertainty is due in part to the future levels of anthropogenic burning of fossil fuels, future precipitation patterns, and also variations in how vegetation might react to changes in climate and increased levels of CO2. Future management may also need to cross culture, institutional, and policy barriers owing to the scale and scope of impending climate change.
There is also an unprecedented need for partnerships between research and management agencies to understand and mitigate the negative effects that an altered climate will have on our natural resources. Finally, although the current scientific consensus regarding climate change is based on thousands of papers published in peer-reviewed journals, this knowledge base continues to evolve.