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|Title:||Vegetation and environmental gradients of the Prudhoe Bay region, Alaska|
|Authors:||University of Colorado, Boulder. Institute of Arctic and Alpine Research.|
Walker, D. A. (Donald A.)
|Publisher:||Cold Regions Research and Engineering Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: The Prudhoe Bay region is a particularly interesting area of tundra because of its well-defined and steep environmental gradients, the combination of which has not been described elsewhere in the Arctic. It is a region of wet coastal tundra that has a unique substrate pH gradient, due in part to its coastal location. The prevailing northeast winds distribute loess from the Sagavanirktok River over most of the region. Areas downwind from the river have alkaline tundra with a gradient of declining soil pH values away from the river;. the northwest portion of the region is not downwind from the river and consequently has acidic tundra. The coastal temperature gradient is among the steepest in the Arctic. Three of Young's (1971) four floristic zones, which are based on the amount of total summer warmth, are present within the region. The effects of the temperature gradient can be seen in the increase of the total number of plants in the flora and the increased plant productivity, particularly of shrubs, as one moves inland. The predominantly wet landscape also creates steep vegetation gradients within elevation changes of a few centimeters. Small hummocks and higher microsites associated with ice wedge polygon relief may be elevated only 10-25 cm above the level of saturated soils but can support rich mesic tundra plant communities. Thus each point in the tundra of the Prudhoe Bay region is a product of numerous microscale, mesoscale and macroscale environmental gradients. This study examines these three scales of environmental gradients and their effects on the vegetation. Data from 92 permanent study plots are presented to document 42 vegetation types. Maps of the region (Walker et al. 1980) are analyzed to determine how the gradients affect the mapped vegetation and landform units. At the microscale, soil moisture, soil pH, percentage of organic matter, soil nutrients, snow depth, hummock size, cryoturbation and animal activity are examined. Pearson's correlation analysis is used to explore the relationships between variables and the cover data for each plant species. The mesoscale variables that are examined are all related to the loess gradient. The effects of loess on the soils and composition of the vegetation are studied using the same techniques as for the microscale variables. The macro scale portion of the study focuses on the effects of the steep coastal temperature gradient. A floristic analysis examines the flora with respect to the temperature, soil moisture and cryoturbation gradients. A willow study correlates summer warmth with the width of growth rings and the height of Salix lanata ssp. richardsonii along a 100-km north-south transect. A vegetation zonation of the coastal plain in the vicinity of the Sagavanirktok River based only on shrub height is also presented.
|Appears in Collections:||CRREL Report|