Tundra Travel Modeling Project Executive Summary


Alaska Department of Natural Resources,
Division of Mining, Land and Water
with the financial and technical assistance of the
U.S. Department of Energy,
Yale University School of Forestry, and
Alaska Oil and Gas Association.

Prepared By:
Harry R. Bader, Northern Region Land Manager-Alaska DNR
Jacynthe Guimond, Alaska DNR Contract Consultant

Acknowledgements to:
Prof. Timothy G. Gregoire, Yale University School of Forestry and Environment
(for assistance with study design and data analysis)
Dr. Jonathan Reuning-Scherer, Yale University School of Forestry and Environment
(for model construction)

Special appreciation to interns:
Todd Nichols, University of Alaska; Alison Macalady, Yale University;
Jonathan Fiely, University of Alaska; Sherri Wall, University of Alaska;
Dean Kildaw, University of Alaska and Patricia Bradwell, University of Oregon.
and to the
Alaska Support Industry Alliance for logistical support

The findings contained in this report reflect the work of the Alaska Department of Natural Resources only. Collaborators U.S. Dept. of Energy, Yale University, and the Alaska Oil and Gas Association retain the right to disagree with analyses and descriptions contained herein.



This project is intended to provide natural resource managers with objective, quantitative data to assist decision making regarding cross country tundra travel typically associated with hydrocarbon exploration and development on the North Slope of the Alaskan arctic. The analyses contained herein make no recommendations concerning the environmental conditions when such travel is appropriate. That determination is an issue of policy balancing left to the discretion of land managers. These analyses employed data generated by the first ever standardized, controlled field trials, with base line data, to empirically investigate the effects of winter tundra travel in Alaska.

The project found interaction relationships among ground hardness, snow depth, and snow slab thickness with various types of exploration vehicles which affected the subsequent active layer depth, soil moisture, and vegetation productivity in various tundra communities. These results are not inconsistent with anecdotal field observations and the few available published articles in the scientific literature. Statistically significant differences in depth of active layer, soil moisture at a 15 cm depth, soil temperature at a 15 cm depth and the absorption of photosynthetically active radiation were found among treatment cells and among treatment types. In addition to descriptive analyses, four models were constructed to address physical soil properties. For the purposes of this study, DNR assumes that changes in the abiotic factors of active layer depth and soil moisture drive alteration in tundra vegetation structure and composition.

Two models, one predicting change in the depth of active layer and a second predicting change in soil moisture were created for the wet graminid/moist sedge shrub communities of the coastal plain. Two more models for change in depth of active layer and soil moisture were constructed for the tussock tundra communities which dominate more rolling terrain typically found in the foothills. In addition to the four models, this report discusses the limited potential management utility in using soil temperature, the amount of photosynthetically active radiation absorbed by plants, and changes in micro-topography as tools for the identification of disturbance in the field.

Because of the lack of variability in snow depth cover throughout the period of field experimentation, these models were unable to thoroughly investigate the interaction role between snow depth and disturbance. Therefore, these models can only be employed after a minimum threshold snow depth of 15 cm has been attained in wet sedge environments and 23 cm in tussock tundra.

The amount of change in disturbance indicators associated with the treatments was found to be greater in tussock tundra than in wet/moist sedge tundra. However, the over all level of change in both community types was generally less than expected. The project found that in the wet sedge tundra, characteristic of the coastal plain, ground hardness and snow slab thickness were the most important environmental ameliorators of disturbance regarding active layer depth and soil moisture. In tussock tundra, only snow cover appeared to play an important role in ameliorating the level of change in active layer depth and soil moisture as a result of treatment. Once certain minimum thresholds for ground hardness, snow slab thickness, and snow depth are attained, it appears that little or no additive effect is realized regarding increased resistance to disturbance in the tundra communities studied.

The project recommends that further monitoring of the plots continue to determine if the changes detected within the study sites increase or decrease over time. If unanticipated change occurs, the model should be altered to take into account new information. In addition, the project recommends that a rigorous program of in-field monitoring of cross tundra travel activity be instituted to verify if disturbance changes materialize consistent with model predictions. Finally, the project recommends DNR institute an adaptive management approach, anticipating an iterative process as new data is collected and the model is improved.



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