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Relationships among environmental variables and distribution of tree species at high elevation in the Olympic Mountains

January 1, 1998

Relationships among environmental variables and occurrence of tree species were
investigated at Hurricane Ridge in Olympic National Park, Washington, USA. A transect
consisting of three plots was established down one north-and one south-facing slope in
stands representing the typical elevational sequence of tree species. Tree species
included subalpine fir (Abies lasiocarpa), Douglas-fir (Pseudotsuga menziesii), mountain
hemlock (Tsuga mertensiana), and Pacific silver fir (Abies amabilis). Air and soil
temperature, precipitation, and soil moisture were measured during three growing
seasons. Snowmelt patterns, soil carbon and moisture release curves were also
determined. The plots represented a wide range in soil water potential, a major
determinant of tree species distribution (range of minimum values = -1.1 to -8.0 MPa for
Pacific silver fir and Douglas-fir plots, respectively). Precipitation intercepted at plots
depended on topographic location, storm direction and storm type. Differences in soil
moisture among plots was related to soil properties, while annual differences at each
plot were most often related to early season precipitation. Changes in climate due to a
doubling of atmospheric CO2 will likely shift tree species distributions within, but not
among aspects. Change will be buffered by innate tolerance of adult trees and the inertia
of soil properties.

Publication Year 1998
Title Relationships among environmental variables and distribution of tree species at high elevation in the Olympic Mountains
Authors Andrea Woodward
Publication Type Article
Publication Subtype Journal Article
Series Title Northwest Science
Index ID 1015692
Record Source USGS Publications Warehouse
USGS Organization Forest and Rangeland Ecosystem Science Center