Climate Change Vulnerability and Adaptation in the Northern Rocky Mountains: Part 2
This resource was submitted by the Climate Risk Institute for use by theCanAdapt Climate Change Adaptation Community of Practice.
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The Northern Rockies Adaptation Partnership (NRAP) is a science-management partnership consisting of 15 national forests in the Northern Region of the Forest Service, U.S. Department of Agriculture (USFS); 3 national parks; the USFS Pacific Northwest and Rocky Mountain Research Stations; the University of Washington; and numerous other organizations and stakeholders. These organizations worked together over a period of 2 years to identify climate change issues relevant to resource management in the Northern Rocky Mountains (USA) and to find solutions that can minimize negative effects of climate change and facilitate transition of diverse ecosystems to a warmer climate. The NRAP provided education, conducted a climate change vulnerability assessment, and developed adaptation options for national forests and national parks that manage more than 28 million acres in northern Idaho, Montana, northwestern Wyoming, North Dakota, and northern South Dakota.
Global climate models project that the Earth’s current warming trend will continue throughout the 21st century in the Northern Rockies. Compared to observed historical temperature, average warming across the five NRAP subregions is projected to be about 4 to 5 °F by 2050, depending on greenhouse gas emissions. Precipitation may increase slightly in the winter, although the magnitude is uncertain.
Climatic extremes are difficult to project, but they will probably be more common, driving biophysical changes in terrestrial and aquatic ecosystems. Droughts of increasing frequency and magnitude are expected in the future, promoting an increase in wildfires, insect outbreaks, and nonnative species. These periodic disturbances, will rapidly alter productivity and structure of vegetation, potentially altering the distribution and abundance of dominant plant species and animal habitat.
Highlights of the vulnerability assessment and adaptation options for the Northern Rockies include the following:
Water resources and infrastructure
- Effects: Decreasing snowpack and declining summer flows will alter timing and availability of water supply, affecting agricultural, municipal, and public uses in and downstream from national forests, and affecting other forest uses such as livestock, wildlife, recreation, firefighting, road maintenance, and instream fishery flows. Declining summer low flows will affect water availability during late summer, the period of peak demand (e.g., for irrigation and power supply). Increased magnitude of peak streamflows will damage roads near perennial streams, ranging from minor erosion to extensive damage, thus affecting public safety, access for resource management, water quality, and aquatic habitat. Bridges, campgrounds, and national forest facilities near streams and floodplains will be especially vulnerable, reducing access by the public.
- Adaptation options: Primary adaptation strategies to address changing hydrology in the Northern Rockies include restoring the function of watersheds, connecting floodplains, reducing drainage efficiency, maximizing valley storage, and reducing hazardous fuels. Tactics include adding wood to streams, restoring beaver populations, modifying livestock management, and reducing surface fuels and forest stand densities. Primary strategies for infrastructure include increasing the resilience of stream crossings, culverts, and bridges to higher peakflows and facilitating response to higher peakflows by reducing the road system and disconnecting roads from streams. Tactics include completing geospatial databases of infrastructure (and drainage) components, installing higher capacity culverts, and decommissioning roads or converting them to alternative uses. It will be important to map aquifers and alluvial deposits, improve monitoring to provide feedback on water dynamics, and understand the physical and legal availability of water for aquifer recharge. Erosion potential to protect water quality can be addressed by reducing hazardous fuels in dry forests, reducing nonfire disturbances, and using road management practices that prevent erosion.
- Effects: Decreased snowpack will shift the timing of peakflows, decrease summer low flows, and in combination with higher air temperature, increase stream temperatures, all of which will reduce the vigor of cold-water fish species. Abundance and distribution of cutthroat trout and especially bull trout will be greatly reduced, although effects will differ by location as a function of both stream temperature and competition from nonnative fish species. Increased wildfire will add sediment to streams, increase peakflows and channel scouring, and raise stream temperature by removing vegetation.
- Adaptation options: Primary strategies to address climate change threats to cold-water fish species include maintaining or restoring functionality of channels and floodplains to retain (hence, to cool) water and buffer against future changes, decreasing fragmentation of stream networks so aquatic organisms can reach similar habitats, and developing wildfire use plans that address sediment inputs and road failures. Adaptation tactics include using watershed analysis to develop integrated actions for vegetation and hydrology, protecting groundwater and springs, restoring riparian areas and beaver populations to maintain summer baseflows, reconnecting and increasing off-channel habitat and refugia, identifying and improving stream crossings that impede fish movement, decreasing road connectivity, and revegetating burned areas to store sediment and maintain channel geomorphology. Removing nonnative fish species and reducing their access to cold-water habitat reduces competition with native fish species.
- Effects: Increasing air temperature, through its influence on soil moisture, is expected to cause gradual changes in the abundance and distribution of tree, shrub, and grass species throughout the Northern Rockies, with more drought-tolerant species becoming more competitive. The earliest changes will be at ecotones between lifeforms (e.g., upper and lower treelines). Ecological disturbance, including wildfire and insect outbreaks, will be the primary facilitator of vegetation change, and future forest landscapes may be dominated by younger age classes and smaller trees. High-elevation forests will be especially vulnerable if disturbance frequency increases significantly. Increased abundance and distribution of nonnative plant species, as well as the legacy of past land uses, create additional stress for regeneration of native forest species.
- Adaptation options: Most strategies for conserving native tree, shrub, and grassland systems focus on increasing resilience to chronic low soil moisture (especially extreme drought and low snowpack), and to more frequent and extensive ecological disturbance (wildfire, insects, nonnative species). These strategies generally include managing landscapes to reduce the severity and patch size of disturbances, encouraging fire to play a more natural role, and protecting refugia where fire-sensitive species can persist. Increasing species, genetic, and landscape diversity (spatial pattern, structure) is an important “hedge your bets” strategy that will reduce the risk of major loss of forest cover. Adaptation tactics include using silvicultural prescriptions (especially stand density management) and fuel treatments to reduce fuel continuity, reducing populations of nonnative species, potentially using multiple genotypes in reforestation, and revising grazing policies and practices. Rare and disjunct species and communities (e.g., whitebark pine, quaking aspen) require adaptation strategies and tactics focused on encouraging regeneration, preventing damage from disturbance, and establishing refugia.
- Effects: A longer growing season is expected to increase net primary productivity of many rangeland types, especially those dominated by grasses, although responses will depend on local climate and soil conditions. Elevated atmospheric carbon dioxide may increase water use efficiency and productivity of some species. In many cases, increasing wildfire frequency and extent will be particularly damaging for big sagebrush and other shrub species that are readily killed by fire. The widespread occurrence of cheatgrass and other nonnative species facilitates frequent fire through annual fuel accumulation. In montane grasslands, wildfire may kill Douglas-fir and other species that have recently established in rangelands through fire exclusion. Shrub species that sprout following fire may be very resilient to increased disturbance, but may be outcompeted by more drought-tolerant species over time. ii
- Adaptation options: Adaptation strategies for rangeland vegetation focus on increasing resilience of rangeland ecosystems, primarily through control and prevention of invasion by nonnative species. Ecologically based management of nonnative plants focuses on strategies to repair damaged ecological processes that facilitate invasion, and seeding of desired native species can be done where seed availability and dispersal of these species are low. Proactive management to prevent establishment of nonnative species is also critical (early detection-rapid response), including tactics such as weed-free policies, education of employees and the public, and collaboration among multiple agencies to control weeds. Livestock grazing can also be managed through the development of site-specific indicators that inform livestock movement guides and allow for maintenance and enhancement of plant health.
- Effects: Few data exist on the direct effects of climatic variability and change on most animal species. Therefore, projected climate change effects must be inferred from what is known about habitat characteristics and the autecology of each species. Habitat for mammals that depend on high-elevation, snowy environments, whether predators (Canada lynx, fisher, wolverine) or prey (snowshoe hare), is expected to deteriorate relatively soon if snowpack continues to decrease. Species that are highly dependent on a narrow range of habitat (pygmy rabbit, Brewer’s sparrow, greater sage-grouse) will be especially vulnerable if that habitat decreases from increased disturbance (e.g., sagebrush mortality from wildfire). Species that are mobile or respond well to increased disturbance and habitat patchiness (deer, elk) will probably be resilient to a warmer climate in most locations. Some amphibian species (Columbia spotted frog, western toad) may be affected by pathogens (e.g., amphibian chytrid fungus) that are favored by a warmer climate.
- Adaptation options: Adaptation strategies for wildlife are focused on maintaining adequate habitat and healthy wildlife populations, and increasing knowledge of the needs and climate sensitivities of species. Connectivity is an important conservation strategy for most species in the Northern Rockies. Maintaining healthy American beaver populations will provide riparian habitat structure and foraging opportunities for multiple species. Quaking aspen habitat, which is also important for several species, can be enhanced by allowing wildfire, protecting aspen from grazing, and reducing conifer encroachment. Restoration of open stands of ponderosa pine and mixed-conifer forest through reduction of stand densities will benefit species such as fisher and flammulated owl. Excluding fire and reducing nonnative species will maintain sagebrush habitats that are required by several bird and mammal species.
- Effects: Recreation has a significant economic impact throughout the Northern Rockies. A warmer climate will generally improve opportunities for warm weather activities (hiking, camping, sightseeing) because it will create a longer time during which these activities are possible, especially in the spring and fall “shoulder seasons.” However, it will reduce opportunities for snow-based, winter activities (downhill skiing, cross-country skiing, snowmobiling) because snowpack is expected to decline significantly in the future. Recreationists will probably seek more water-based activities in lakes and rivers as refuge from hotter summer weather. Higher temperatures may have both positive and negative effects on wildlife-based activities (hunting, fishing, birding) and gathering of forest products (e.g., berries, mushrooms), depending on how target habitats and species are affected.
- Adaptation options: Recreationists are expected to be highly adaptable to a warmer climate by shifting to different activities and different locations, behavior that is already observed from year to year. For example, downhill skiers may switch to ski areas that have more reliable snow, cross-country skiers will travel to higher elevations, and larger ski areas on Federal lands may expand to multi-season operation. Water-based recreationists may adapt to climate change by choosing different sites that are less susceptible to changes in water levels. Hunters may need to adapt by altering the timing and location of hunts. Federal management of recreation is currently not very flexible with respect to altered temporal and spatial patterns of recreation. This can be at least partially resolved by assessing expected use patterns in a warmer climate, modifying opening times of facilities, and deploying seasonal employees responsible for recreational facilities earlier in the year.
- Ecosystem services are increasingly valued on Federal lands, beyond just their economic value. Climate change effects will vary greatly within different subregions of the Northern Rockies, with some ecosystem services being affected in the short term and others in the long term. Of the many ecosystem services provided in the Northern Rockies, eight are considered here, most of which are relevant to other resource categories included in the assessment.
- Although annual water quantity (or water yield or water supply) is not expected to change significantly, timing of water availability is likely to shift, and summer flows may decline. These changes may result in some communities experiencing summer water shortages, although reservoir storage can provide some capacity. Rural agricultural communities will be disproportionately affected by climate change if water does become limiting.
- Water quality will decrease in some locations if wildfires and floods increase, adding sediment to rivers and reservoirs. Agriculture is currently the major source of impairment, affecting riparian systems, aquatic habitat, water temperatures, and fecal coliform. Climate change is expected to amplify these effects. Hazardous fuels treatments, riparian restoration, and upgrading of hydrologic infrastructure can build resilience to disturbances that damage water quality.
- Wood products are a relatively small component of the Northern Rockies economy, and economic forces will probably have the biggest impacts in the future. As wildfires and insect outbreaks become more common, wood supply could become less reliable, but overall effects will generally be small except in small towns that depend on a steady timber supply.
- Minerals and mineral extraction are important economic drivers in eastern Montana and western North Dakota. The biggest effects on this industry will be economic factors and factors related to how it connects to other ecosystem services, particularly water quality. Wildfires and floods can put mineral extraction infrastructure at risk in some watersheds.
- Forage for livestock is expected to increase in productive grasslands as a result of a longer growing season and in some cases elevated carbon dioxide. Therefore, ranching and grazing may benefit from climate change. Primary effects on grazing include loss of rural population, spread of nonnative grasses, and fragmentation of rangelands.
- Viewsheds and air quality will be negatively affected by increasing wildfires and longer pollen seasons. A growing percentage of the Northern Rockies population will be in demographic groups at risk for respiratory and other medical problems on days with poor air quality. Treatments of hazardous fuels can help build resilience to disturbances that degrade air quality.
- Regulation of soil erosion will be decreased by agricultural expansion, spread of nonnative plants, and increased frequency of wildfire and floods. Increased capital investments may be needed for water treatment plants if water quality declines significantly. Climate-smart practices in agriculture and road construction can reduce some negative effects.
- Carbon sequestration will be increasingly difficult if wildfires, insect outbreaks, and perhaps plant disease increase as expected, especially in the western part of the Northern Rockies. At the same time, managing forests for carbon sequestration is likely to become more important in response to national policies on carbon emissions. Hazardous fuel treatments can help build resilience to disturbances that rapidly oxidize carbon and emit it to the atmosphere.
Disturbances such as wildfires, floods, and soil erosion place cultural and heritage values at risk. Damage to cultural and historic sites is irreversible, making protection a key management focus. Climate-induced changes in terrestrial and aquatic habitats affect abundance of culturally valued plants and animals (especially fish), affecting the ability of Native American tribes to exercise their treaty rights. Effects on cultural resources are amplified by external social forces that include a growing regional population, vandalism, and loss of traditional practices in a globalizing culture.
Citation: Halofsky, Jessica E.; Peterson, David L.; Dante-Wood, S. Karen; Hoang, Linh; Ho, Joanne J.; Joyce, Linda A., eds. 2018. Climate change vulnerability and adaptation in the Northern Rocky Mountains. Gen. Tech. Rep. RMRSGTR-374. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. Part 2. pp. 275–475.