WRDS Library [Home]
Digital Library Publications Videos Card Catalog

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 (unpublished data) observed significantly reduced conductances following near-freezing or subfreezing nights.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


  WRDS Library [Home]
Digital Library Publications Videos Card Catalog