Responses of leaf gas exchange to environmental variation in two widely dispersed Juniperus species versus a narrowly restricted endemic, Petrophytum cinerascens (Juniperus occidentalis, J. osteosperma)

I determined how ecophysiological characteristics of Juniperus occidentalis and Juniperus osteosperma changed along elevational and regional environmental gradients in the Great Basin. Two north-south groupings were realized based on daily carbon assimilation (north, 157.6 {dollar}mu{dollar}mol g{dollar}sp{lcub}-1{rcub}{dollar}s{dollar}sp{lcub}-1{rcub};{dollar} south, 113 {dollar}mu{dollar}mol g{dollar}sp{lcub}-1{rcub}{dollar}s{dollar}sp{lcub}-1{rcub}){dollar}, but these groupings are not solely related to environment and cut across species boundaries. The two species functioned similarly across large elevational and regional variation in environment, perhaps explaining their ability to persist and grow over a wide range of environmental conditions.; I also determined that when Petrophytum cinerascens, a highly restricted endemic found in eastern Washington, was grown at increased temperatures, photosynthesis did not acclimate (30/16 = 11.07, 34/20 = 9.43 and {dollar}rm 38/24spcirc C = 6.4 mu mol msp{lcub}-2{rcub}ssp{lcub}-1{rcub}).{dollar} The large decrease in photosynthesis with increased temperature indicate global warming may be detrimental to P. cinerascens. In contrast to the Juniperus species, P. cinerascens is not very physiologically flexible and may serve as an indicator of global change.