Presentation Title

Effects of elevation above the thalweg on species composition, water potential, and stomatal conductance in the California Sycamore, Red Willow, Arroyo Willow, and Mule’s-Fat in the Angeles National Forest.

Start Date

November 2016

End Date

November 2016

Location

HUB 302-#104

Type of Presentation

Poster

Abstract

Plant species occurring in periodic or permanent inundation by shallow water are considered to be characteristic of wetlands. Species which occur in wetlands are often subject to highly variable moisture conditions and exercise different mechanisms in order to tolerate these conditions. In this study, we consider how elevation above the thalweg effects species composition, water potential, and stomatal conductance in the California Sycamore (Platanus racemose), Red Willow (Salix laevigata), Arroyo Willow (Salix lasiolepis), and Mule’s-Fat (Baccharis salicifolia) in Monte Cristo Creek, in the Angeles National Forest. To determine density, we conducted a survey of woody plant individuals occurring along a 62 meter transect from the thalweg to the edge of the bank using 1 X 12 meter plots. Of the 148 individuals surveyed, 54 were indicators of wetland. A frequency analysis determined only some areas along the transect to be considered wetland. Individuals occurring further from the thalweg are prone to experience less water and, as a result, increased water stress. However, predawn and midday water potentials demonstrated no significant differences as elevation above the thalweg increased. The behavior of individuals as they respond to water stress can be analyzed by their stomatal conductance. Stomatal conductance measurements of the Arroyo Willow were taken every 2 hours. Arroyo Willow occurring at 36 meters had higher stomatal conductance than those occurring at 12, 20, and 46 meters. Although the Arroyo with the highest stomatal conductance occur at 36 meters, their change in elevation actually place them closer to the thalweg.

This document is currently not available here.

Share

COinS
 
Nov 12th, 4:00 PM Nov 12th, 5:00 PM

Effects of elevation above the thalweg on species composition, water potential, and stomatal conductance in the California Sycamore, Red Willow, Arroyo Willow, and Mule’s-Fat in the Angeles National Forest.

HUB 302-#104

Plant species occurring in periodic or permanent inundation by shallow water are considered to be characteristic of wetlands. Species which occur in wetlands are often subject to highly variable moisture conditions and exercise different mechanisms in order to tolerate these conditions. In this study, we consider how elevation above the thalweg effects species composition, water potential, and stomatal conductance in the California Sycamore (Platanus racemose), Red Willow (Salix laevigata), Arroyo Willow (Salix lasiolepis), and Mule’s-Fat (Baccharis salicifolia) in Monte Cristo Creek, in the Angeles National Forest. To determine density, we conducted a survey of woody plant individuals occurring along a 62 meter transect from the thalweg to the edge of the bank using 1 X 12 meter plots. Of the 148 individuals surveyed, 54 were indicators of wetland. A frequency analysis determined only some areas along the transect to be considered wetland. Individuals occurring further from the thalweg are prone to experience less water and, as a result, increased water stress. However, predawn and midday water potentials demonstrated no significant differences as elevation above the thalweg increased. The behavior of individuals as they respond to water stress can be analyzed by their stomatal conductance. Stomatal conductance measurements of the Arroyo Willow were taken every 2 hours. Arroyo Willow occurring at 36 meters had higher stomatal conductance than those occurring at 12, 20, and 46 meters. Although the Arroyo with the highest stomatal conductance occur at 36 meters, their change in elevation actually place them closer to the thalweg.