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GLEES (Glacier Lakes Ecosystem Experiments Site)

Scientist in Charge: 

General Description

The Glacier Lakes Ecosystem Experiments Site is a high elevation wilderness-like site where research is conducted to determine the effects of atmospheric deposition and climate change on alpine and subalpine aquatic and terrestrial ecosystems and the upper treeline ecotone. The GLEES 600 ha research watershed has complex mountainous terrain varying from 3200 to 3500 m elevation. Long-term physical, chemical, and biological monitoring is an important component of the activities at GLEES.

Check out the GLEES Brochure for more information.

Aerial view of the Glacier Lakes Ecosystem Experiment Site (GLEES).
Aerial view of the Glacier Lakes Ecosystem Experiment Site (GLEES).

Background Information and History

See the General Technical Report The Glacier Lakes Ecosystem Experiments Site for more information about GLEES.


Foster, Adrianna C. ; Shuman, Jacquelyn K. ; Shugart, Herman H. ; Dwire, Kathleen A. ; Fornwalt, Paula J. ; Sibold, Jason ; Negron, Jose , 2017
Frank, John M. ; Massman , William J. , Jr ; Swiatek, Edward ; Zimmerman, Herb A. ; Ewers, Brent E. , 2016
Chen, Fei ; Zhang, Guo ; Barlage, Michael ; Zhang, Ying ; Hicke, Jeffrey A. ; Meddens, Arjan ; Zhou, Guangsheng ; Massman , William J. , Jr ; Frank, John M. , 2015
Speckman, Heather N. ; Frank, John M. ; Bradford, John B. ; Miles, Brianna L. ; Massman , William J. , Jr ; Parton, William J. ; Ryan, Michael G. , 2015
Frank, John M. ; Massman , William J. , Jr ; Ewers, Brent E. ; Huckaby, Laurie Kay Stroh ; Negron, Jose , 2014
Musselman, Robert (Bob) C. ; Korfmacher, John L. , 2014
Schlaepfer, Daniel R. ; Ewers, Brent E. ; Shuman, Bryan N. ; Williams, David G. ; Frank, John M. ; Massman , William J. , Jr ; Lauenroth, William K. , 2014
Mensing, Scott A. ; Korfmacher, John L. ; Minckley, Thomas ; Musselman, Robert (Bob) C. , 2012
Bradford, John B. ; Weishampel, Peter ; Smith, Marie-Louise ; Kolka, Randall ; Birdsey, Richard A. ; Ollinger, Scott V. ; Ryan, Michael G. , 2010
Yi, Chuixiang ; Ricciuto, Daniel ; Li, Runze ; Wolbeck, John ; Xu, Xiyan ; Nilsson, Mats ; Frank, John M. ; Massman , William J. , Jr , 2010
Bradford, J.B. ; Birdsey, R.A. ; Joyce, L.A. ; Ryan, M.G. , 2008
Binkley, Dan ; Kashian, Daniel M. ; Boyden, Suzanne ; Kaye, Margot W. ; Bradford, John B. ; Arthur, Mary A. ; Fornwalt, Paula J. ; Ryan, Michael G. , 2006
Musselman, Robert (Bob) C. ; Massman , William J. , Jr ; Frank, John M. ; Korfmacher, John L. , 2005
Zeller, Karl ; Zimmerman, Gary ; Hehn, Ted ; Donev, Evgeny ; Denny, Diane ; Welker, Jeff , 2001
Zeller, Karl ; Harrington, Debra ; Riebau, Al ; Donev, Evgeny. , 2000
Sommerfeld, R. A. ; Lundquist, J. E. ; Smith, J. , 2000
Takle, E. S. ; Brandle, J. R. ; Schmidt, R. A. ; Garcia, R. ; Litvina, I. V. ; Doyle, G. ; Zhou, X. ; Hou, Q. ; Rice, C. W. ; Massman , William J. , Jr , 2000
Moir, W. H. ; Rochelle, Shannon G. ; Schoettle, Anna W. , 1999
Musselman, Robert (Bob) C. ; Zeller, Karl F. ; Nikolov, Nedialko T. , 1998
Schoettle, Anna W. ; Moir, William , 1998
Massman , William J. , Jr ; Sommerfeld, R. A. ; Mosier, A. R. ; Zeller, K. F. ; Hehn, T.J . ; Rochelle, S. G. , 1997
Wooldridge, G. ; Zeller, K. ; Musselman, Robert (Bob) C. , 1997
Regan, Claudia M. ; Musselman, Robert (Bob) C. ; Haines, June D. , 1997
Sommerfeld, Richard A. ; Massman , William J. , Jr ; Musselman, Robert (Bob) C. , 1996
Wooldridge, G. L. ; Musselman, Robert (Bob) C. ; Sommerfeld, R. A. ; Fox, D. G. ; Connell, B. H. , 1996
Williams, Mark W. ; Baron, Jill S. ; Caine, Nel ; Sommerfeld, Richard ; Sanford, Robert Jr. , 1996
Musselman, Robert (Bob) C. ; Hudnell, Laura ; Williams, Mark W. ; Sommerfeld, Richard A. , 1996
Connell, Bernadette H. ; Miller, David R. , 1995
Reuss, J. O. ; Vertucci, F. A. ; Musselman, Robert (Bob) C. ; Sommerfeld, R. A. , 1995
Massman , William J. , Jr ; Sommerfeld, Richard ; Zeller, Karl ; Hehn, Ted ; Hudnell, Laura ; Rochelle, Shannon , 1995
Musselman, Robert (Bob) C. ; Wooldridge, Gene L. ; Massman , William J. , Jr ; Sommerfeld, Richard A. , 1995
Musselman, Robert (Bob) C. , 1994
Reuss, John O. ; Vertucci, Frank A. ; Musselman, Robert (Bob) C. ; Sommerfeld, Richard A. , 1993
Sommerfeld, R. A. ; Mosier, A. R. ; Musselman, Robert (Bob) C. , 1993
Brooks, P. D. ; Schmidt, S. K. ; Sommerfeld, R. ; Musselman, Robert (Bob) C. , 1993
Sommerfeld, R. A. ; Rocchio, J. R. , 1993
Saunders, James F. III ; Belk, Denton ; Dufford, Richard , 1993
Conklin, Martha H. ; Sommerfeld, Richard A. ; Laird, S. Kay ; Villinski, John E. , 1993
Wooldridge, G. ; Musselman, Robert (Bob) C. ; Connell, B. ; Fox, D. , 1992
Monson, Russell K. ; Grant, Michael C. ; Jaeger, Charles H. ; Schoettle, Anna W. , 1992
Sommerfeld, Richard A. ; Conklin, Martha H. ; Laird, S. Kay , 1992
Sommerfeld, R. A. ; Musselman, Robert (Bob) C. ; Reuss, J. O. , 1991
Sommerfeld, R. A. ; Musselman, Robert (Bob) C. ; Wooldridge, G. L. ; Conrad, M. A. , 1991
Sommerfeld, R. A. ; Musselman, Robert (Bob) C. ; Wooldridge, G. L. , 1990
Bales, Roger C. ; Sommerfeld, Richard A. ; Kebler, David G. , 1990
Musselman, Robert (Bob) C. ; Wooldridge, Gene L. ; Fox, Douglas G. ; Connell, Bernadette H. , 1990
Fox, Douglas G. ; Schoettle, Anna W. ; Vertucci, Frank A. , 1987

Ecological Information

GLEES hydrologic, geologic, soil, and floristic characteristics

  • Small alpine/subalpine watershed and subcatchments with interconnected snowfield, first order streams, wetlands and glacial cirque lakes.

  • Nearby alpine lakes of similar surface area and depth, but differing in watershed area, inflow patterns (open vs. closed systems), turnover rates, stratification, snow cover, deposition input, water chemistry and aquatic biota.

  • Lakes with low buffering capacity, sensitive to atmospheric deposition.

  • Ecotone between alpine and subalpine, accessible year round.

  • Exposed and slow-weathering bedrock.

  • Talus slopes and shallow immature soils having low base saturation.

  • Alpine and subalpine vegetation - 304 vascular plant species in 14 distinct forest, meadow, shrub, and krummholz plant associations.

  • Old-growth forests with trees > 700 years old.

  • Almost 200 phytoplanton species identified.

  • A harsh environment with high winds, low temperatures, and snow cover (and ice covered lakes) 7-8 months each year.

Research – Historical and Present

Nitrogen deposition

Increasing levels of nitrogen deposition have been reported for the Rocky Mountains, particularly in high elevation alpine watersheds of the Colorado Front Range. Understanding the consequences of increased nitrogen on plant productivity, community structure, and ecosystem function is important to land management decisions in alpine and wilderness areas. Long-term monitoring of atmospheric deposition at GLEES has indicated that no significant increases in nitrogen deposition have yet taken place. GLEES deposition data act as a critical baseline for comparison for other alpine and subalpine sites that are impacted by deposition.

Riparian hydrology and chemistry

High elevation environments in the western United States are sensitive to the effects of atmospheric deposition of pollutants, including chemical components of “acid rain”. Yet little is known about the movement of these pollutants, such as ammonium, oxides of nitrogen, and sulfur dioxide, within the hydrological systems of the alpine environments. The near-stream spatial and temporal gradients of nitrates in the soil solute is the focus of a study.

Nitrogen cycling in riparian ecosystems

A study is underway to examine the sources and sinks of nitrogen in a subcatchment of GLEES. Isotopic signatures of nitrogen and oxygen will be used to identify sources of nitrate in the system. The research will identify the importance of different landscape types in nitrogen cycling. The study is a cooperative effort of Colorado State University and the Rocky Mountain Research Station.

The dynamics of disturbance on subalpine forests

A study has been initiated to identify disturbance events and to quantify their relationship to the formation of gaps in the forest canopy of the subalpine forest. A network of plots to examine this question of forest stand dynamics has been established at the GLEES and the nearby Snowy Range Natural Area.

Dendrochronology in the subalpine forest at GLEES:

The science of dendrochronology offers a powerful tool to aid in understanding ecosystem processes, especially as influenced by past disturbances, climatic change, and forest growth and development. Researchers are developing tree-ring width chronologies and documenting maximum age structures in the sub-alpine forest stands in and near GLEES.

Seedling germination and survival at the alpine-subalpine ecotone

Ecotones are edges of species' distributions, hence they may provide early indications of biological effects of a changing physical and chemical climate. However, it is not currently known if there is a predictable pattern to dynamic changes in ecotones under natural conditions, in particular, the distribution of seedlings survival. Plots have been established at GLEES to examine the relationship between patterns of seedling establishment and biotic and abiotic factors at multiple scales (10 cm - 25 m). These plots will also be used to follow seedling establishment and survival over time and relate these dynamics to regional climate patterns.

Relevance to Land Management

GLEES has been ideal for developing and testing techniques to monitor Air Quality Related Values (AQRVs) in wilderness-type ecosystems. It is recommended as a research site for evaluation of new questions identified from the Federal Land Managers AQRV Workgroup (FLAG) Phase I Report as research needs to be explored for FLAG Phase II. Intensive research can be conducted without the restrictions imposed on wilderness. The site is accessible in winter by snow machine and has relatively light recreation use impact. 

Long-term Monitoring and Data

Meteorological observations

An 15-meter tower equipped with standard meteorological sensors is located at 3286 m elevation between East and West Glacier Lakes. Data are captured every 15 minutes and include:

  • Soil temperature at 0.5 and 20 cm soil depths

  • Surface wetness

  • Air temperature

  • Relative humidity

  • Wind speed

  • Wind direction

  • Solar radiation

  • Daily high-resolution imagery of the West Glacier Lake area (expected availability summer 2022)

Hour meteorology tower data is available for the Glacier Lakes Ecosystem Experiments Site tower (1989-2021) and NADP site (WY00; 1991-2005) through the U.S. Forest Service Research Data Archive.

Wet deposition

GLEES is home to two data collection installations that are part of the nationwide National Atmospheric Deposition Program / National Trends Network (NADP/NTN). Site WY95, near Brooklyn Lake, was established in 1991 and Site WY00, near West Glacier Lake, was established in 1987. Precipitation samples are collected weekly at these sites for the purpose of assessing atmospheric chemical deposition in the form of rain and snow.

Samples are then shipped to a central analytical laboratory operated by the Illinois State Water Survey, where they are analyzed for SO4, NO3, Cl, PO4, Na, K, Ca, Mg, NH4, and H. Each site is equipped with an ETI NOAH-IV rain gage which records precipitation data at 15-minute intervals. NADP data are available from the network, including the NADP Site WY95 and NADP Site WY00.

Dry deposition

As part of the nationwide Clean Air Status and Trends Network (CASTNet), dry deposition and ozone are sampled weekly at the GLEES Brooklyn monitoring site (CASTNet site #169).

Established in 1987, CASTNet includes 92 monitoring stations across the United States. The majority of the monitoring stations are operated under contract to EPA's Office of Air and Radiation. In conjunction with state and local monitoring efforts, the CASTNet monitoring network is used to determine the effectiveness of emissions control programs.

The CASTNet site at GLEES measures atmospheric concentrations of sulfate, nitrate, ammonium, sulfur dioxide, and nitric acid, and continuous ambient ozone. The GLEES site is equipped with a temperature controlled shelter, ozone analyzer, a filter pack sampling system, datalogger, cellphone modem, and a voice radio phone modem. Filter packs are exposed for 1-week intervals at a flow rate of 3.0 liters per minute and sent to a contract laboratory in Florida for chemical analysis. Information on CASTNet is available at:

Snow quantity and water content

The Natural Resources Conservation Service (NRCS) has a SNOTEL (Brooklyn Lake, Wyoming Site #365) site at 3115 m elevation near Brooklyn Lake that remotely samples all precipitation; the minimum, maximum and average temperature; snow depth; and water content.

Carbon dioxide flux measurements

The AMERIFLUX site at GLEES measures inputs and outputs of carbon dioxide above the forest
The AMERIFLUX site at GLEES measures inputs and outputs of carbon dioxide above the forest
Ambient atmospheric carbon dioxide, a major contributor to global warming, has steadily increased during the past century. Yet, for all of its importance to radiationally driven atmospheric warming, the global budget of carbon dioxide is still not well known. In an effort to better define the global carbon budget, the AMERIFLUX group has been formed to measure carbon dioxide fluxes using eddy covariance data.

The AMERIFLUX effort is closely coordinated with similar international efforts such as the EUROFLUX. We have established an AMERIFLUX site at GLEES. To support the AMERIFLUX effort, we have installed flux measurements instrumentation on the Brooklyn 30 m tower. Our goal is to obtain flux data at the tower site as continuously as possible for the next 5 years. The AMERIFLUX network is described at:

Historic background data

  • A long history of alpine vegetation research and meteorological monitoring exists at the site and surrounding area. Data were collected on alpine ecosystems by University of Wyoming ecologists in the 1950's.

  • The Snowy Range Observatory network was established in the 1960's to collect temperature and precipitation data.

  • In the early 1990's, GLEES was part of a monitoring program pairing research sites in the United States with similar sites in Eastern Europe. GLEES was paired with a site on Mt. Elbrus, Russia.

Current data

GLEES has a rich data archive of air quality and meteorological data, and an extensive research effort in this ecosystem shown to be sensitive to atmospheric deposition. An extensive collection of meteorological, hydrological, water chemistry, snow chemistry, wet and dry deposition, geological, soils, snow cover, aquatic, floristic, and topographic information exists in the GLEES data archive. Checklists of terrestrial vascular plant species, phytoplankton, periphyton, zooplankton, and macroinvertebrates have also been assembled.

Some of these data are available online (see below); other data are available upon request from the GLEES manager.

Current research installations include:

  • AmeriFlux equipment/installation

  • Two NADP/NTN deposition facilities with rain gages

  • CASTNet site #169

  • Instrumented watersheds (East West Glacier Lake) with gaging flumes for two inlet streams and two outlet streams, with data collected from first snowmelt (early May) through autumn freeze-up

  • Vegetation survey plots suitable for repeated botanical and plant community data collection

Facilities Information

Location and Facilities

  • GLEES is in the Snowy Range of the Medicine Bow Mountains, 55 km west of Laramie, and 15 km NW of Centennial, Wyoming representative of Class I wilderness areas on public lands.

    Map showing the location of GLEES in Wyoming.
    Map showing the location of GLEES in Wyoming.

  • The GLEES Centennial Cabin, located 2 km northwest of Centennial, Wyoming and 10 km from the GLEES, is used for housing and as a staging site for field research. The cabin also houses fully equipped wet and dry laboratories and a site-specific herbarium.

  • Two Forest Service campgrounds are located adjacent to GLEES.


  • Located on the Laramie Ranger District, Medicine Bow National Forest (MBNF).

  • Management similar to wilderness ecosystems with off road motorized (except over snow) vehicles allowed. Removed from grazing allotment and mining claims in the 1990's. Timber harvest permitted only for maintenance of roads, trails and campgrounds.

  • Research managed by the USDA Forest Service, Rocky Mountain Research Station

  • Close cooperation with MBNF management and RMRS for research dealing with management concerns.

  • A field site manager coordinates field operations at the site.

Research Opportunities

Scientists from universities, other federal agencies, and other research institutions are invited to participate in the research at this site. Please contact Dr. Kate Dwire, GLEES scientist-in-charge.