THE VEGETATION AND ENVIRONMENTAL GRADIENTS OF THE PRUDHOE BAY REGION, ALASKA. (VOLUMES I AND II).

摘要

This study examines the environment-vegetation gradients within the Prudhoe Bay region at micro-, meso, and macro-scales. It focuses on analysis of maps and vegetation information in the Geobotanical Atlas of the Prudhoe Region, Alaska (Walker et al. 1980). The analysis is preceeded by an overview of the region that includes topography, geology, climate, soils, wildlife, oil field facilities and environmental impacts. Data from 92 permanent study plots are presented to document 44 vegetation types. Detailed colored vegetation maps of a 140 km('2) area are also included.; The moisture gradient is the most important micro-scale variable and accounts for most of the regional variation on geobotanical maps. Map boundaries of landforms, soils, and vegetation maps are controlled, for the most part, by variations in patterned-ground forms. Soil moisture affects a variety of measured soil properties including organic matter, pH, and nutrient regimes. Plant taxa respond to these various gradients in complex ways.; The major meso-scale gradients are related to loess distributed downwind from the Sagavanirktok River. The loess is carbonate-rich silt that causes distinct gradients for soil pH, soil texture, and organic matter. Several nutrients are also affected. The loess creates distinctive patterns in the vegetation.; Macro-scale studies include a floristic analysis and a study of willow stature related to the steep coastal temperature gradient. These patterns are related to the glacial history of northern Alaska and Canada, the Pleistocene land-bridge connection to Asia, and also the presence of large rivers flowing out of the Brooks Range. Floristics are also related to the moisture, temperature, and cryoturbation gradients.; The willow study documents a dramatic response of Salix lanata spp. richardsonii height with respect to increased summer temperature along a 100 km transect from the coast to the northern edge of the foothills of the Brooks Range. Temperatures are also correlated with growth-ring widths. The floristic and willow studies are related to a suggested vegetation zonation for the Coastal Plain in the vicinity of the Sagavanirktok River.