The effects of decreased wash water on Olneya tesota (desert ironwood) at Corn Springs, California.

摘要

A comparison of Olneya tesota responses to a reduction in overland water runoff was conducted at Corn Springs, CA, within the Sonoran Desert. It was hypothesized that trees with access to overland water runoff would have a different ecophysiological and morphological response than trees that did not have access to overland water runoff. The ecophysiological and morphological responses measured were water potentials, leaf carbon isotope ratios, leaf mass per area, branch growth, flower production, seed production, and tree population densities. Predawn water potentials and branch growth were found to be significantly different (p=0.0016 and p=0.02). The predawn water potentials indicate an increased water stress in trees not exposed to overland water runoff. The branch growth indicates that trees exposed to overland water runoff had an average branch length for one growing season of 29.1cm, whereas trees not exposed to overland water runoff had an average length of 20.1cm, demonstrating that trees with access to overland water runoff are responding to that water.; The lack of difference in delta13C, leaf mass per area, flowers per 0.25m3, and seeds per pod, may indicate that environmental conditions, especially water availability, were similar in both treatment areas during the production of these structures. As a result, future work should include oxygen and hydrogen isotope ratios, instantaneous water use efficiency, and tree canopy and volumes.