Abstract – Climate change vulnerability and adaptation in the N Cascades region


Climate change vulnerability and adaptation in the North Cascades region, Washington.
Raymond, C.L.; Peterson, D.L.; Rochefort, R.M. 20xx. Gen. Tech. Rep. PNW-GTR-xxx. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. Xxx p..

The North Cascadia Adaptation Partnership (NCAP) is a science-management partnership consisting of M. Baker-Snoqualmie National Forest, Okanogan-Wenatchee National Forest, North Cascades National Park Complex, Mount Rainier National Park, the U.S. Forest Service Pacific Northwest Research Station, and the University of Washington Climate Impacts Group. These organizations worked with numerous stakeholders over two years to identify climate change issues relevant to resource management in the North Cascades and to find solutions that will facilitate the transition of the diverse ecosystems of this region into a warmer climate. The NCAP provided education, conducted a climate change vulnerability assessment, and developed adaptation options for federal agencies that manage 2.4 million hectares in north-central Washington. 

In the Pacific Northwest, the current warming trend is expected to continue, with average warming of 2.1 °C by the 2040s and 3.8 °C by the 2080s; precipitation may vary slightly, but the magnitude and direction are uncertain. This warming will have far-reaching effects on aquatic and terrestrial ecosystems. Hydrologic systems will be especially vulnerable as North Cascades watersheds become increasingly rain dominated, rather than snow dominated, resulting in more autumn/winter flooding, higher peak flows, and lower summer flows. This will greatly affect the extensive road network in the North Cascades (longer than 16 000 km), making it difficult to maintain access for recreational users and resource managers. It will also greatly reduce suitable fish habitat, especially as stream temperatures increase above critical thresholds. In forest ecosystems, higher temperature will increase stress and lower the growth and productivity of lower elevation tree species on both the west side and east side of the Cascade crest, although growth of high-elevation tree species is expected to increase. Distribution and abundance of plant species may change over the long term, and increased disturbance (wildfire, insects, and invasive species) will cause rapid changes in ecosystem structure and function across broad landscapes, especially on the east side. This in turn will alter habitat for a wide range of animal species by potentially reducing connectivity and late-successional forest 

Coping with and adapting to altered climate change effects will become increasingly difficult after the mid-21st century, although adaptation strategies and tactics are available to ease the transition to a warmer climate. For roads and infrastructure, tactics for increasing resistance and resilience to higher peak flows include: install hardened stream crossings, stabilize stream banks, design culverts for projected peak flows, and upgrade bridges and increase their height. For fisheries, tactics for increasing resilience of salmon to altered hydrology and higher stream temperature include: restore stream and floodplain complexity, reduce road density near streams, increase forest cover to retain snow and decrease snow melt, and identify and protect cold-water refugia. For vegetation, tactics for increasing resilience to higher temperature and increased disturbance include: accelerate development of late-successional forest conditions by reducing density and diversifying forest structure, manage for future range of variability in structure and species, include invasive species prevention strategies in all projects, and monitor changes in tree distribution and establishment at tree line. For wildlife, tactics for increasing resilience to altered habitat include: increase diversity of age classes and restore a patch mosaic, increase fuel reduction treatments in dry forests, use conservation easements to maintain habitat connectivity, and remove exotic fish species to protect amphibian populations. 

The NCAP facilitated the largest climate change adaptation effort on federal lands to date, including many participants from other organizations to promote an all-lands approach to addressing climate change. It achieved specific elements of national climate change strategies for the U.S. Forest Service and National Park Service, providing a scientific foundation for resource management and planning in the North Cascades region. Rapid implementation of adaptation in sustainable resource management will enhance the potential for North Cascades ecosystems to maintain long-term functionality in future decades.