ARCUS 14th Annual Meeting and Arctic Forum 2002

Biocomplexity of Frost Boil Ecosystem on the Arctic Slope, Alaska

Donald A. Walker¹, Vladimir E. Romanovsky², William B. Krantz³, Chien L. Ping⁴, Rorik A. Peterson ⁵, Martha K. Raynolds⁶, Howard E. Epstein⁷, Jiong G. Jia⁸, David C. Wirth^9
1Institute of Arctic Biology, University of Alaska, PO Box 757320, Fairbanks, AK, 99775, USA, Phone 907-474-2460, Fax 907-474-7666, ffdaw@uaf.edu
²Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK, 99775, USA, Phone 907-474-7459, Fax 907-474-7290, ffver@uaf.edu
³Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Campus Box 450, Boulder, CO, 80309, USA, Phone 303-492-7517, Fax 303-492-4637, krantz@spot.colorado.edu
⁴Department of Plant, Animal, and Soil Sciences, Palmer Research Center, 533 E Fireweed Avenue, Palmer, AK, USA, Phone 907-746-9462, Fax 907-746-2677, pfclp@uaa.alaska.edu
⁵USA
⁶Institute of Arctic Biology, University of Alaska Fairbanks, PO Box 757000, Fairbanks, AK, 99775, USA, Phone 907-474-2459, fnmkr@uaf.edu
⁷Department of Environmental Sciences, University of Virginia, PO Box 400123, Charlottesville, VA, 22904, USA, Phone 434-924-4308, Fax 434-982-2137, hee2b@virginia.edu
⁸Department of Environmental Sciences, University of Virginia, PO Box 400123, Charlottesville, VA, 22904, USA, Phone 434-982-2337, Fax 434-982-2137, jj4u@virginia.edu
⁹USA

The central goal of this project is to understand the complex linkages between biogeochemical cycles, vegetation, disturbance, and climate across the full summer temperature gradient in the Arctic in order to better predict ecosystem responses to changing climate. We focus on frost-boils because: (1) The processes that are involved in the self-organization of these landforms drive biogeochemical cycling and vegetation succession of extensive arctic ecosystems. (2) These ecosystems contain perhaps the most diverse and ecologically important zonal ecosystems in the Arctic and are important to global carbon budgets. (3) The complex ecological relationships between patterned-ground formation, biogeochemical cycles, and vegetation and the significance of these relationships at multiple scales have not been studied. (4) The responses of the system to changes in temperature are likely to be nonlinear, but can be understood and modeled by examining the relative strengths of feedbacks between the components of the system at several sites along the natural arctic temperature gradient.

We propose to examine disturbed and undisturbed patches associated with frost-boil ecosystems, from polar deserts of northern Canada to shrub tundra systems in Alaska. Frost boils are caused by soil heave in small, regularly spaced, circular highly disturbed patches, 1-3 m in diameter. The processes of frost-boil formation is currently poorly understood, so full knowledge of the biogeochemical system first requires a better understanding of the process of frost heave itself and how it is modified by interactions with climate and vegetation. A recent Differential-Frost-Heave (DFH) model by Peterson and Krantz provides considerable insight to the self-organization processes in frost boils. This physically based model can predict many phenomena associated with frost boils including the amount of heave, spacing and size of the boils. Early model results suggest that the ground-surface temperature is a primary control of frost-boil formation. Vegetation and/or snow cover can constrain the development of frost boils by insulating the soils. Climate and the level of disturbance caused by frost heave strongly influence the rate of organic-matter accumulation and biogeochemical cycles within the tundra soils. We will examine the full implications of this interaction by studying how frost heave affects nitrogen and carbon pools and rates of nitrogen mineralization along the climate gradient. We propose to answer six major questions related to the biocomplexity of frost-boil ecosystems:
(1) How does the self-organization associated with frost boils occur?
(2) How does the frost heave affect the soil biogeochemical processes within and between the frost boils?
(3) How do frost heave and biogeochemical processes affect plant communities?
(4) How do the biological processes in turn feed back to control frost heave?
(5) How do interactions between biogeochemistry, cryotrubation and vegetation change along the existing arctic climate gradient?
(6) How do the complex patterns associated with frost boils affect the tundra systems in a hierarchy of spatial-temporal scales?

The response of the system to summer temperature is nonlinear. We propose to dissolve the complex system in into linear models by examining the relationship between frost heave, carbon, nitrogen, and vegetation at a series of sites within five bioclimatic subzones along the temperature gradient. We will use ordination, path analysis, and information theory to examine the complex multivariate relationships between biogeochemistry, cryotrubation, vegetation, and the environment. We hypothesize that zonal sites in areas with intermediate summer warmth should have the highest measures of several key ecosystem functions (e.g., mineralization rates, nitrogen pools, biodiversity). In years 1 and 2, the field studies will focus along the Dalton Highway in northern Alaska. This region is well known and provides an exceptional opportunity because it has a particularly sharp boundary that demarcates essentially High-Arctic soils with abundant frost boils from Low Arctic soils with few frost boils. Extensive ecosystem, snow, and ground-temperature data are available from several sites in this region. In years 2, 3 and 4, we will extend the research into more remote areas in the Canadian Arctic where there are colder bioclimate subzones not represented in northern Alaska.

To arrive at a predictive capability for biogeochemical response and plant community formation, we will use output from the DFH model to help parameterize a vegetation-change model (ArcVeg). The project has four research components: (1) Frost Boil Dynamics, Climate, and Permaforst, (2) Soil and Biogeochemistry, (3) Vegetation, and (4) Modeling Nutrient and Vegetation Dynamics. We also propose a major educational component of the study. Students, as part of Dr. Bill Gould’s Arctic Field Ecology course, will interact with the scientists. They will be actively engaged in the research activities as part of expeditions that will allow them to study biocomplexity in the Arctic. We are also proposing to host an arctic biocomplexity workshop early in the project and a synthesis workshop in Year 4.

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