Global Change Research -- A Focus on Mountain Ecosystems

Dan Fagre - Program Coordinator, US Geological Survey, Northern Rocky Mountain Science Center, Glacier Field Station, West Glacier, MT 59936; email: dan_fagre@usgs.gov

Americans are more aware than ever before that global climate changes are taking place. What do these changes mean for our national parks and western mountains and their role in protecting unique natural resources?  To answer such questions, an interdisciplinary team from the U.S. Geological Survey, National Park Service, U.S. Forest Service, and the University of Montana has conducted 9 years of research at Glacier National Park. The primary objective was to understand how this 1.1 million acre mountain wilderness responds to present climatic variability and other external stressors such as air pollution so that impacts of future global environmental change can be predicted.

To accomplish this, first we established how major ecosystem components are influenced by current and past climatic patterns. Developing computer-based ecosystem models which can organize available information and, in computer code, represent our existing knowledge of ecological relationships was instrumental in reaching an understanding of complex mountain system dynamics. To produce management-relevant information, and anticipate the future state of Glacier Park, ecosystem modeling also was used simulate ecosystem outputs for potential future conditions. Liberal use of new technologies in remote sensing and Geographic Information Systems were married to new modeling techniques to produce quantitative estimates, 3D maps, and computer animations of ecosystem dynamics. The Regional Hydro-Ecological Simulation System and FIRE-BGC are interacting computer models we built to estimate ecosystem attributes, such as tree distribution, density, and size, using information from satellites and existing digital representations of landscapes. In addition to predicting what is there, the models can estimate how the parts are interacting. For instance, when we incorporated climate data for Glacier Park, the models calculated and visually displayed daily estimates of snow pack density, soil moisture, evapotranspiration, stream discharge and other dynamic ecosystem attributes for a 150 mi² mountain watershed. Thus, for any part of the park on any given day, it is possible to get a prediction of specific measures of the ecosystem’s condition.

To ensure that the computer-based view of the ecosystem was accurate, key ecosystem outputs such as stream discharge were monitored at numerous sites for 7 years and results compared to the model outputs. Close matches between the computer-estimated and actual ecosystem measurements suggested that the basic responses of Glacier Park to climate were accounted for by the models. This meant that possible future climate scenarios could be put into the models to reveal how this mountain ecosystem might look and act in the future. With a future 30% increase in precipitation and a slight increase in annual average temperature (currently the most likely climate scenario for Glacier Park within 50 years), the cedar-hemlock forests are favored to expand in lower elevations but coarse woody debris accumulation and other forest responses increase the frequency of large, stand-replacing forest fires in other areas. Testing slightly different future climate conditions, we found stream temperatures rise earlier in the summer, altering the abundance and distribution of stream organisms while subalpine fir trees become more nitrogen-stressed at treeline.

As our confidence in the modeling grew, we applied it to new research questions and used it to assess management options under future possible scenarios. For instance, model outputs identified parts of the upper McDonald watershed which would experience earlier and greater stream temperature increases. This area would be a candidate for intensive monitoring to detect early change and would provide a cost-effective alternative to a more extensive and expensive monitoring program. Model simulations suggest where future fire danger will be greatest within the park but also that implementing a prescribed natural fire program to address continued fuel accumulation would lead to significant air quality degradation. Much of the modeling work is summarized in a book, Forest Ecosystems: Analysis at Multiple Scales by Richard Waring (Oregon State University, Department of Forest Science) and Steven Running (University of Montana, Numerical Terradynamic Simulation Group) and in a recent Ecological Applications publication.

Watershed Research
Seven years of monitoring and investigations into aquatic system responses to climate change were summarized in a publication (Fagre et. al), and 2 manuscripts from collaborators recently accepted for publication (Hauer et al., Lowe et al.).  Since 1992, we have recorded the lowest spring discharge and second highest spring discharge of the past 30 years (based on SNOTEL records), thereby capturing much of the high interannual variance in this system. We also have documented an unusual run-off event in late fall and its impacts on the biota. Such "spring discharges" in fall are forecast to become frequent under some climate change scenarios. In addition to the eight primary stream monitoring sites, we have also collected detailed stream temperature recordings from over 20 other sites located along the stream continuum ranging from the alpine to the valley and have placed up to 10 additional remote temperature recording devices in alpine and floodplain sites. These efforts have underscored the thermal complexity present in this watershed and the complicated spatial changes which would occur under future climate changes. These stream/wetland complexes possess diverse temperature regimes, are concentrated zones of biogeochemical cycling, and have diverse aquatic faunal assemblages containing rare species. Many of these species have very narrow habitat requirements and will respond quickly to thermal changes as temperature is the predominant limiting factor in these basins. Thus far, we have identified over two-hundred species distributed along the stream/wetland elevation gradient in the McDonald and St. Mary basins in Glacier National Park. We have detailed analyses of species distributions along the stream continuum; however, we know much less about the thermally complex stream/wetland systems of the alpine and floodplains. Furthermore, it is these sites which appear to be most sensitive to hydrologic and thermal variation that may be driven by climatic change and will be our focus for the next several years. see University of Montana, Flathead Lake Biological Station.

Glacier Monitoring
Our emphasis on future climate change begs the questions: Will climate change really occur? Glacier's ecosystem has already changed in response to a warming climate. One of the most visually dramatic changes is the shrinkage of glaciers, which, in turn, affect other parts of the ecosystem. Less than 1/3 of the glaciers present in 1850 exist today and most remaining glaciers are mere remnants of their previous size. Such irrefutable evidence of climatic change is one reason Vice-President Al Gore chose Glacier’s backdrop in September 1997 to underscore his views on the serious threats climate change presents to Americans. We will be using recently acquired aerial photography to map and estimate the present size of remaining glaciers. We recently summarized the rates of glacier recession in a contribution to a satellite atlas of the world’s glaciers (Key et al.). see Glacier retreat in Glacier National Park, Montana and Predicting the Impact of Climate Change on Glacier and Vegetation Distribution in Glacier National Park to the Year 2100

Repeat photography
The Glacier Park archives contain approximately 12,000 historic photographs going back to the late 1800s. Many of these photographs are of glaciers, snowfields, alpine meadows, treeline, and avalanche paths which potentially have changed in response to climate shifts. During summer 1998, Karen Holzer and Lisa McKeon returned to the exact location from which selected historic photographs were taken and took new photographs to document the extent of environmental change. Both the old and new photographs were then digitally scanned and cropped so that exact comparisons could be made between photographs. This project is ongoing but completed comparisons already have visually underscored the dynamic nature of some mountain features. see Grinnell Glacier Photo Gallery and Panoramic Photographs of Glacier.

Spatial changes in Alpine Vegetation Patterns
Fritz Klasner concluded his M.S. at Oregon State University with a paper analyzing a 46-year history of alpine treeline changes using sequential aerial photography. Elevational changes in treeline did not occur but the transition from trees to tundra became more abrupt because krummholz patches filled existing spaces. Additionally, more krummholz became upright patch forests, increasing stand density. Areas with trails had more krummholz fragmentation than those with no trails but, overall, the impact of trails was not significant compared to climate change. see Spatial Changes in Alpine Treeline Vegetation Patterns and Changing Alpine Treeline Ecotone.

Spring Opening of the Going-to-the-Sun Road
The Going-to-the-Sun-Road in Glacier is one of the National Park Service’s premier attractions and the most heavily used facility in the park. The road traverses the park from the west entrance at West Glacier, crosses the Continental Divide at Logan Pass, and descends to the plains and Blackfeet Indian Reservation at St. Mary. A document in preparation focuses on the annual opening of the GTSR with a west-side approach to Logan Pass, the spring plowing operations this entails, and available snow and weather data. From the perspective of climate change, or conversely park management working safely to open the road each year, moving the average opening date of the Going-to-the-Sun Road in either direction (earlier or later) within the snowpack accumulation and melt cycle has potential safety implications. Traditional safety concerns of increasing avalanche danger and snow instability associated with earlier opening as well as other hazardous conditions resulting from rock slides, slope failures (landslides), and surface ice formation are identified. see Natural hazards of Spring Opening of the Going-to-the-Sun Road.

Atmospheric Research
A Brewer spectrophotometer was installed at St. Mary in August 1997 and the first year of data indicated peak levels of ozone and UV-B radiation during July and August. This effort is part of the PRIMENet network of national parks monitoring impacts of atmospheric stressors on natural resources. These data will be part of the first long-term national assessment of UV-B radiation patterns associated with thinning ozone layers in the upper atmosphere. Locally, these data can be related to changes in amphibian populations, which may be sensitive to UV-B increases. A specific examination of amphibian habitats was conducted with a portable spectrophotometer at several ponds during summer 1998 by USGS scientists. The monitoring activities are summarized in a recent fact sheet by Lisa McKeon. see UV Monitoring at Glacier National Park.

THE FUTURE
The first phase of Global Change funding was concluded in September 1998. A national competition for new research projects was conducted by USGS last summer. Several of our proposed projects were successful in being awarded funding for the next 5 years. Our research at Glacier Park will be extended to the North Cascades and Olympic National Parks to compare mountain ecosystem responses to climate change along a gradient from maritime (Olympic) to continental (Glacier) conditions. We will test the model’s capabilities to estimate other mountain ecosystem processes and specifically examine the influence of climatic variability and disturbance on those processes. Additional research projects will focus on alpine treeline dynamics, ecosystem effects from changing snow chemistry, and the interaction of amphibian metapopulation dynamics with UV-B exposure in mountain habitats. These projects are just starting but will contribute to our understanding of mountain ecosystem processes. Although it is never possible to know exactly what the future holds, our increasing capability to evaluate potential scenarios with new knowledge will improve the decisions being made now about our natural resources. see CLIMET (Climate-Landscape Interactions on a Mountain Ecosystem Transect) and Glacier National Park, Montana: Spectral-Field Analyses of Vegetation at the Alpine Treeline Ecotone

RECENT PRODUCTS

Fagre, D. B. 1999(in press). Understanding climate change impacts on Glacier National Park's natural resources. Pages 00-00 In M. Mac, P. A. Opler, C. E. Haecker-Puckett, P. D. Doran, and L. S. Huckaby, eds. Status and trends of the nation's biological resources. US Department of Interior. Washington, D.C. 000 pp.

White, J. D., S. W. Running, P. E. Thornton, R. E. Keane, K. C. Ryan, D. B. Fagre, and C. H. Key. 1998. Assessing simulated ecosystem processes for climate variability research at Glacier National Park, USA. Ecological Applications. 8(3): 805-823.

U.S. Department of the Interior, U.S. Geological Survey
Northern Rocky Mountain Science Center, BOX 173492, Montana State University, Bozeman, Montana, 59717-3492
Maintainer: mrblair@usgs.gov
Last Modified: 25 April 2003 11:22
URL: http://nrmsc.usgs.gov/research/global.htm