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
DISCLAIMER
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.
EXECUTIVE SUMMARY
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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