Introduction to Tundra Travel and the Modeling Project

A Serious Problem. A serious problem is confronting oil exploration in this state: the winter oil exploration season is becoming ever shorter. The Alaska Department of Natural Resources (DNR) opens the North Slope tundra to exploration when the ground is frozen enough that companies can explore over snow without significantly damaging the tundra. But these openings were coming later and later because of warming weather, regulatory changes, and changes in measuring techniques. In fact, the winter exploration season has been effectively cut in half since the early 1970s.

Serious Consequences. Shorter seasons are a real problem for the oil industry who is trying to explore new areas further from road systems on the North Slope. In order to prevent declining oil production, companies need to explore for new oil reservoirs. It's also a problem for Alaskans who rely on the oil industry: in other words, for all of us. We need to lengthen the season, but we need to do so in a way that respects the environment.

Solving the Problem. To solve this problem, DNR's Division of Mining, Land and Water worked with the US Department of Energy to develop scientifically valid, peer-reviewed research to find ways to extend the season without compromising the environment. The study analyzed the changes on tundra test plots when various equipment used for exploration were driven on the plots during various stages of tundra freeze up and snow conditions. Data was collected over a year and half and then processed through statistical analysis to understand the complicated interaction of environmental conditions and variables. We created a statistical model that helps us understand what expected tundra disturbance will be experienced as the result of using various vehicles in certain conditions.

Good News. DNR found that the Tundra is much more resistant than was anticipated. The study defined the hardness of ground needed to protect the tundra in different tundra ecosystems and what other contributing factors were important. With the better understanding of how the tundra resists disturbance, we found that we can advance the tundra opening dates. If the conditions were the same as the last few years, we could have opened the tundra three to six weeks earlier with no increased tundra disturbance beyond that experienced at the later opening dates. Last year, where we opened some areas on December 23 rd and others as late as January 28 th , we could have opened all of the North Slope areas to winter travel in early December!

Lengthening a 3-month exploration season by a month will be a very important change for the oil industry and for all Alaskans. This increase in the exploration season, combined with DNR's focus on approving ice road projects may allow companies to complete exploration wells within one season rather than two. This will allow Alaskans to receive the benefits of oil development and oil revenues sooner than would otherwise occur. It is an important win for the companies and for Alaskans.

The Next Step. DNR will closely monitor the initial vehicle use after the opening date to field test the new application of the study results. In addition DNR will work with the educational community to monitor the study plots over time to better understand the resiliency of the tundra. With the data collected and further monitoring there are more insights we can learn about the tundra resistance to disturbance. That may provide additional choices for the oil industry in how they configure their equipment in order to begin exploration activities sooner.

More Information. For more information contact Melissa Head, 451-2719 or email at

The Technical Details of the Study

Two test locations were selected to generate a model for each of the two primary ecosystems found on the North Slope - Coastal Plain and the Foothills. Each study area was divided into rows of treatment cells, each cell measuring 100 by 50 m. containing 30 treatment cells. Within each cell, three 5 m transects were created.

Prior to the winter field tests, each of the 60 cells (30 for each study area) were sampled creating base line data along each of the three transects, in each cell, during July-August, 2003. Base line measurements included: (1) depth of active (thaw) layer, (2) vegetation community type; (3) vegetation composition by genera (established with a hybrid "point frame"/ "intersect" sampling system); (4) percent vegetation life form cover (using the same hybrid sampling system); (5) soil temperature at a depth of 10 cm; (6) soil moisture at a depth of 10 cm; (7) soil micro-topography; (8) tussock frequency and condition; (9) shrub frequency and condition; and (10) vegetation productivity as measured by chloroplast density estimated with the percent of photosynthetically active radiation (PAR) absorbed.

Each cell within a particular study area was then randomly assigned one of six treatment dates and one of five treatment types. The day before each treatment date, winter measurements were taken along each transect within the treated cells for that date. Winter measurements included: (1) snow depth; (2) ground hardness; (3) snow slab presence; and (4) snow slab thickness.

Treatments consist of an assigned vehicle type making five consecutive figure-eight passes within an assigned cell on an assigned date, passing over each of the three transects within the cell. Each treatment cell, therefore, had only a single vehicle type pass through the transects on a single date. Treatment dates were designed to span a suite of environmental conditions potentially present during tundra travel. Treatment dates were established for: (1) October 30 2003; (2) November 14, 2003; (3) December 4, 2003; (4) December 16, 2003; (5) January 5, 2004; and January 20, 2004.

Five treatment vehicle types were used on each test date. The five vehicle types are as follows: (1) steel tracked caterpillar D-7 dozer; (2) wheeled front-end loader; (3) cleat tracked tucker snowcat; (4) rubber tracked challenger and a (5) "no treatment" treatment. Vehicle types were selected upon the basis of (1) equipment availability and transportability, and (2) type of equipment frequently used in cross tundra travel for seismic exploration and ice road construction.

After the winter field season, DNR returned to the two study areas during the following summer in July-August, 2004 to re-measure each transect in each treatment cell for change detection. Natural ecological disturbance and change will be accounted for, and calibrated, by referencing to change detected within the "no treatment" cells using the summer 2003 measurements with the subsequent summer 2004 measurements. In this fashion, disturbance is defined as a change from based line exceeding that observed for natural inter-annual variation for each of the measurements.

Data from the 2003 and 2004 field seasons is integrated into a multiple regression model enabling DNR staff to predict disturbance responses under differing combinations of environmental conditions with known types and intensity of tundra travel. This model provides enhanced information and serves the Director as an additional tool for DNR in deciding appropriate opening dates for winter tundra travel.


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