Gas exchange of co-occurring plant species of the Great Basin Desert in an irrigated common garden

honors thesisCollege of ScienceBiologyDiane E. PatakiThe majority of plants in the Great Basin ecosystem have adapted to cope with drought during summer. While general characteristics of these plants have been studied in non-managed environments it is important to investigate the physiology of these plants when additional water is supplied. In this study, leaf level gas exchange was measured in Artemisia tridentata and Ericameria nauseosa that were grown in a managed and irrigated common garden (wet treatment) as well as in a non-managed "natural" environment (dry treatment). Measurements included photosynthesis (A), transpiration (E), stomatal conductance (gs) and instantaneous water use efficiency (WUE) which were evaluated in response to soil moisture as well as atmospheric vapor pressure deficit (D). Overall, A, E and gs were all higher in plants that were grown in the wet treatment than the dry treatment. A and gs increased with soil moisture, but decreased with increasing D. E had a positive correlation with soil moisture but no relationship with D in A. tridentata; however, in E. nauseosa, E was related positively to D and had no apparent relationship with soil moisture. Stomata closure with increasing D is common as a strategy to conserve water as well as to avoid cavitation. Surprisingly, WUE was not significantly different between the two watering treatments. This study also shows that specific leaf areas (SLA) was higher in the wet treatment than the dry treatment for E. nauseosa but were not distinguishable for A. tridentata. These findings illustrate the importance in best management practices for irrigation and plant selection in cities since plant responses have direct effects on cooling and carbon sequestration