Symposium 9: Rocky Mountain Futures: Preserving, Utilizing, and Sustaining Rocky Mountain Ecosystems

Abstract

Symposium 9 was organized by Jill Baron and was held on Tuesday, 7 August 2012 at the ESA Annual Meeting in Portland, Oregon. The report was written by: Jill S. Baron, U.S. Geological Survey, Fort Collins Colorado; Timothy Seastedt, University of Colorado, Boulder, Colorado; Dan Fagre, U.S. Geological Survey, West Glacier, Montana; Jeffrey A. Hicke, University of Idaho, Moscow, Idaho; Diana Tomback, University of Colorado, Denver, Colorado; Elizabeth Garcia, University of California, Santa Barbara, California; Zachary Bowen, U.S. Geological Survey, Fort Collins, Colorado; and Jesse A. Logan, USDA Forest Service (retired), Emigrant, Montana. In 2002 we published Rocky Mountain Futures, an Ecological Perspective (Island Press) to examine the cumulative ecological effects of human activity in the Rocky Mountains. We concluded that multiple local activities concerning land use, hydrologic manipulation, and resource extraction have altered ecosystems, although there were examples where the “tyranny of small decisions” worked in a positive way toward more sustainable coupled human/environment interactions. Superimposed on local change was climate change, atmospheric deposition of nitrogen and other pollutants, regional population growth, and some national management policies such as fire suppression. Ten years later we revisited this profoundly human-influenced landscape with an ESA 2012 Symposium to evaluate the 2002 predictions, and ask whether local decisions still drive ecological change and whether ecological conditions are improving or degrading. As illustrated in the summaries below, we were surprised by the pace with which climate change has restructured mountain ecosystems and by the dramatic increase in energy development due to technical innovation and national policies. Dan Fagre noted that the pace of climate change has been more rapid than anticipated, and ecosystems are responding in unanticipated ways, in “The Indirect Effect of Human Influence on Western Mountain Environments: Vulnerabilities and Resiliencies.” Retreating glaciers and earlier snowmelt affect stream runoff patterns and stream temperature profiles. The distribution and abundance of thermally sensitive stream macroinvertebrates, the foraging behavior of associated salmonids, such as bull trout, and their competitive interactions with invasive lake trout are all at risk. Retreating glaciers add additional nitrogen to high-elevation aquatic systems as they expose new substrate, stimulating high-elevation lakes. Research of the past decade has underscored the dependence of mountain organisms, ranging from wolverines to alpine poppies, on snow cover. The landscape is snow-dependent as well. Avalanches provide wildlife habitat through frequent disturbance. Earlier snowmelt has left some species such as snowshoe hares with white pelage in spring, exposing them to predation. Some organisms show resilience to accelerating climate change through behavioral adaptation. Protection of critical habitats, such as the U.S–Canadian North Fork of the Flathead River, can provide a buffer against change that may increase the resilience of species. Among the consequences of climate change are multiple pressures on Rocky Mountain forests. Diana Tomback, in her talk, “Forest Health Challenges in the Rocky Mountain West,” found that during the past decade general forest health has declined precipitously in the Rocky Mountains, with major changes in forest structure and disturbance patterns. Reduced snowpack and changes in the timing of snowmelt altered local hydrology and water availability, leading to drought stress in many forest communities. Warming trends and drought have caused unprecedented outbreaks of mountain pine beetle and other bark beetles as well as regionally synchronized, high-intensity fires. Invasive plants, pests, and diseases have further altered forest community structure; and distributional shifts in response to climate warming are predicted for all forest trees. Tomback used whitebark pine to illustrate how factors interact to alter forest communities and ecosystem function. White pine blister rust, mountain pine beetle outbreaks, and fire suppression are reducing forest diversity and changing structure, altering stream flows and impacting animals that live in whitebark pine communities or feed on whitebark pine seeds, including Clark's Nutcrackers and grizzly bears. Bark beetle outbreaks were mentioned only a few times in the 2002 book. In their talk, “The Emerging Significance of Bark Beetle Outbreaks in the Rocky Mountains,” Jeffrey Hicke and Jesse Logan noted predictions made in 2001 that warming at the northern and high-elevation range limits of mountain pine beetle would facilitate northward expansion into the boreal forest and upward expansion to high-elevation whitebark pine forests. These predictions have come true. Warming has intensified outbreaks in areas that were once too cold to support large beetle populations. Beetle outbreaks have also occurred in unusual habitats. A warmer drought in the Southwest coupled with bark beetle activity caused pinyon pine mortality across millions of hectares. Large areas of forest in the western U.S. and British Columbia are being killed by bark beetles. Tree mortality affects ecological relationships, subsequent wildfire intensity, human uses of the forest, carbon sequestration, and water cycles. Some options exist for managers to minimize influences of these disturbances, but are not widely applied. By increasing species diversity and diversifying age structure, managers can limit mortality caused by bark beetles, which typically attack one or a few species of host trees. Thinning can promote tree defensive capability and alter the microclimate; both reduce suitability for beetle outbreaks. Monitoring and rapid detection of outbreaking populations can prompt management activities. Pesticides and use of semiochemicals (a chemical emitted by a plant or animal that evokes a behavioral or physiological response in another organism) are options for high-value trees, but not suitable for widespread application. Ultimate management efforts could include reducing greenhouse gas emissions, thereby limiting future warming. Elizabeth Garcia and Naomi Tague picked up on the effects of beetle-caused tree mortality on stream flow and vegetation in their presentation, “A Comparison of Climate Change and Biotic Disturbance on Stream Flow and Carbon Cycling in the Colorado Rocky Mountains.” They applied an ecohydrologic model to the Big Thompson River of Colorado to address how hydrologic changes associated with warming impact vegetation productivity. They further asked how changes in forest structure, such as caused by beetle kill, interact with climate-driven changes to alter stream flow regimes. Warming increased annual stream flow due to increased runoff production during winter and snowmelt periods. Variable precipitation resulted in the large increases in total amount and variability in stream flow. However, the largest increases in total amount of stream flow occurred for bark beetle outbreak scenarios. Minimum flows under beetle scenarios were greater by 150%, whereas climate perturbations had a negligible effect on minimum flows. Model results emphasize that while temperature and precipitation changes may alter stream flow directly, the greatest changes are likely to arise as a result of indirect effects associated with climate–related forest disturbances (Fig. 1). Average (1998–2008) annual stream flow for the Big Thompson River, Colorado, modeled over 20 years, using a variety of disturbance scenarios. From left to right the bars represent: historical average without disturbance (black); 2°C increase of minimum temperatures (orange); high variability annual precipitation (white); 50% of subalpine fir converted to snags as representation of beetle disturbance (pink); 95% of subalpine fir converted to snags (red); 95% of subalpine fir converted to snags modeled with the high-variability precipitation climate. In 2002 the major, ongoing threat to remaining Rocky Mountain grasslands was physical conversion to urban, suburban, exurban, or row agriculture along with the suppression of fire. Fire suppression increased the abundance of shrublands and forests at the expense of grasslands. Exurbanization, fire suppression, and conversion to shrublands have continued since 2002. However, and somewhat ironically, the Rocky Mountain region now is believed to have more grasslands and meadows than in 2002. In his presentation, “Grassland Transformations in the Rocky Mountain West,” Timothy Seastedt suggested there will be more grasslands in our future. The widespread die-off of pines from bark beetles is opening the canopy. Repeated fires are projected to remove woody species' seed and seedling sources, perpetuating grasslands. Fragmentation from energy development, carbon dioxide fertilization effects, and nitrogen deposition alter plant competitive interactions, which, combined with the presence of nonnative species, continue to transform plant species composition of grasslands. Warmer and drier conditions and increases in October to March precipitation are selecting for certain plant species over others. The emergence of hydraulic fracturing (fracking) as an economically feasible way to extract oil and gas found under many regions in the Rockies was not on our radar screen in 2002, but has expanded rapidly during the last decade. Similar rapid growth in wind energy production is attributable predominantly to renewable energy standards for states and federal incentives for production of renewable energy (Fig. 2). In their talk, “Trends and Issues Associated with Energy Development in the West,” Zack Bowen, Tanya Gallegos, Christopher Potter, and David Mott addressed the development of unconventional oil and gas resources and wind power as important drivers of landscape change in the Rocky Mountain Region. Domestic energy production is a national priority, and the Rocky Mountain region is rich in energy resources including coal, oil, natural gas, geothermal, and uranium and has great potential for solar and wind energy. Development of these resources is driven by a combination of technological innovation, incentives, markets, and energy production standards. The pace of change is rapid. Understanding of environmental consequences lags implementation of these new technologies, and incorporation of research results into policy and management decisions takes additional time. The number of wind turbines producing electricity in U.S. Rocky Mountain states (although not necessarily in mountains) from 1996 to 2011. Wind energy development in the Rocky Mountain region has grown rapidly in the last decade, and presents new challenges for land managers responsible for balancing renewable energy development with potential effects on wildlife and wildlife habitat. Data are from the American Wind Energy Association. In the final presentation of the symposium, “Only Fools and Newcomers Predict the Future: the Hubris of Forecasting,” Jill Baron addressed the elements of surprise that may be inevitable to environmental predictions. Rapid climate change has brought about dramatic changes in the hydrologic cycle, including seasonal snow, avalanche, and ice dynamics. Rocky Mountain Futures failed to appreciate how quickly climate change would increase extreme events in restructuring some Rocky Mountain ecosystems. Forests, overwhelmed by drought, beetles, disease, and fire, have been dramatically altered; cascading effects of climate change to food webs and ecosystem processes are only now becoming apparent. National and global energy policies, coupled with innovative technologies, have unleashed unprecedented development of both fossil fuel and renewable energy development. And a stagnant global economy has dramatically slowed immigration, suburban, and exurban development. In response primarily to climate change projections, broad coalitions of stakeholders and resource managers are beginning to consider future scenarios of change as they develop plans for adapting to climate change. Adaptation options range from increased resource use efficiencies to multijurisdictional collaborations for forest, wildlife, and water conservation while facilitating resource development. While some decisions about Rocky Mountain resources are still made locally, they are increasingly influenced by regional, national, and global forces.