WWRC 83-07
Summer Water Relations of Abies lasiocarpa, Picea engelmannii, and Pinus contorta at Higher and Lower Elevation Sites in Southeastern Wyoming
Introduction
Recent studies on conifers of the western United States have
examined the effects of several environmental factors on plant
water stress and leaf conductance to water vapor loss. It has
been demonstrated that with high soil moisture and overnight
temperatures above 4 C, stomatal conductance for Engelmann spruce
(Picea engelmannii Parry ex Engelm.), subalpine fir (Abies
lasiocarpa [Hook.] Nutt.) and lodgepole pine (Pinus contorta
Engelm.) is a function of photosynthetically active radiation
(Kaufmann, 1982a), leaf-to-air absolute humidity difference
(Kaufmann, 1982a), and saturation vapor deficit of the air
(Running, 1980a). Running (1980a) also found that at leaf water
potentials below -1.8 to -2.0 MPa, stomatal conductance was
reduced in lodgepole pine. Moreover, Kaufmann (1982b), Fahey
(1979), and Smith et al. (unpublished data) observed significantly
reduced conductances following near-freezing or subfreezing
nights.
In southeastern Wyoming, Engelmann spruce-subalpine fir
forests range from approximately 2900 m elevation to timberline at
about 3350 m. With increasing elevation, solar irradiance, mean
leaf-to-air temperature differences, and diffusivity of water
vapor increase, while mean air temperature decreases (Smith and
Geller, 1979). With these factors in mind, the purpose of the
present study was to determine changes with elevation in stomatal
conductance to water vapor loss of Engelmann spruce and subalpine
fir, with comparisons to lodgepole pine. The study was conducted
to facilitate the application of a physiologically-based
hydrologic model to spruce-fir forests in Wyoming.
Water Resources Publications List
Water Resources Data System Library |
Water Resources Data System Homepage
