The following are brief summaries of some of the identified climate vulnerabilities and adaptation options in the four major focus areas examined in this case study. Please see Adapting to Climate Change at Olympic National Forest and Olympic National Park for a full description.
Hydrology and Roads:
Climate changes on the Olympic Peninsula are projected to result in many hydrologic changes, such as more precipitation falling as rain rather than snow, decreased snowpack, earlier snowmelt, increased winter precipitation and runoff, increased storm intensity, increased winter and spring streamflows, reduced summer streamflows, increased flood frequency and magnitude, and elevation shifts in transition (rain on snow) zones. This will affect many physical processes that relate to forest road networks and maintenance, including wasting and debris flows, sediment delivery to streams, and floodplain inundation, among others.
Fortunately, road management actions currently taking place on ONF and ONP have focused on increasing the resilience of infrastructure and reducing potential risk to aquatic resources. Many of these activities make sense to continue in light of projected hydrologic changes. Adaptation strategies outlined in the roads workshop range from the physical to the institutional, and include actions such as: evaluating road placement, road design and relocation options; updating culvert guidelines; managing for the risk of road failures; and increasing the flexibility of forest road management policies.
The hydrological impacts discussed above will also have important implications for fish species, particularly salmonids in the region (Salmon, Steelhead, and Bull Trout). In addition to the volume and timing of streamflow, warmer water temperatures are an important consideration. Vulnerabilities vary by species, but can include stress from increased water temperatures during critical life stages such as spawning, freshwater rearing stages, and seaward migration. Flooding events and peak flows could affect egg survival and disrupt migration timing. Positive effects in some streams, through increased productivity and growth rates, are also possible.
Options identified are varied, and include strategic monitoring to look for indications of change or invasion; protecting cold water refugia; continuing to restore habitat especially in areas expected to retain adequate summer flow; improving road crossings and culvert sizing; and limiting mortality through recreational fishing.
Increased temperatures and corresponding increases in summer drought stress and fire frequency in the Pacific Northwest will lead to changing vegetation distribution in the region, resulting in forest types different from those seen today. Changes in plant phenology, increased drought stress, and changing disturbance regimes (storm intensity, insect pests) could lead to changes in plant regeneration patterns. ONF and ONP identified alpine and subalpine meadows, wetlands, and Sitka spruce rain forests as being particularly vulnerable to warming climate.
Collaborators agreed that the primary goal is to continue to maintain functioning ecosystems under future climates. An overarching adaptation strategy would therefore focus on minimizing mass die-off and the effects of major disturbances, while encouraging the maintenance and restoration of structures and processes that are viable over the long term. Actions to achieve this may include thinning to reduce drought stress; maximizing early successional tree species diversity; conserving genetic resources (tree seeds); early detection of exotic species; and consideration of planting native drought-tolerant species after thinning.
Wildlife species on the Olympic Peninsula are expected to respond to both direct and indirect effects of climate change, for example temperature changes that affect physiology (direct) and changes in the phenology and/or distribution of habitat, forage or prey (indirect). These effects are expected to act in combination with other stressors such as habitat loss and fragmentation to affect wildlife. Endemic species, specialists with strict habitat or diet requirements, and high-elevation species may be particularly at risk.
A landscape scale strategy will be particularly important in addressing vulnerable wildlife species. Adaptation responses at this scale can include promoting forests with desired late-successional habitat characteristics, especially near existing late successional forests, to increase landscape connectivity (e.g. through restoration thinning in young-growth forest). At smaller scales (e.g. forest stands), wildlife habitat quality can be improved through actions like creating and protecting legacy structures with high habitat value (snags, downed wood), and protecting and restoring headwater streams.
Please see the complete document for additional information and references.