PARENT SESSION
Contributed Oral Session 54: Urban Plant Communities
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 524 C, Level 5, Palais des congrès de Montréal
Physiology and water use of native and non-native trees in the Salt Lake City, Utah, urban forest.
Bush, Susan1, Pataki, Diane2, Hultine, Kevin1, West, Adam1, Ehleringer, James1, 1 University of Utah, Salt Lake City, UT, USA2 University of California, Irvine, Irvine, CA, USA
ABSTRACT- Afforestation associated with urbanization and land-use change is common in semi-arid cities. Urban forests in these regions are unique in that they are generally composed almost entirely of non-native tree species maintained by irrigation practices. While numerous studies have focused on gas exchange of trees in their native environments, very little is known regarding the physiology and gas exchange of trees subject to environmental conditions markedly different from their native habitat. To assess the impact of dry atmospheric conditions on the physiology and gas exchange of non-native trees in Salt Lake City, Utah, we measured sap flux, water potential, and vulnerability to cavitation of five tree species in the urban forest. We considered both native and commonly planted non-native trees, which included Quercus gambelii, Quercus rubra, Acer platanoides, Platanus occidentalis and Gleditsia triacanthos. Sap flux showed large species differences, particularly with respect to sensitivity to vapor pressure deficit (VPD). These differences appeared to be related to differences in wood anatomy and vulnerability to xylem cavitation. Trees with ring porous wood anatomy were more sensitive to VPD than species with diffuse porous wood anatomy, particularly at average daily VPD values greater than 1 kPa. These results were consistent with xylem cavitation vulnerability and water potential measurements, which indicated that ring porous species were operating with significantly greater xylem embolism relative to diffuse porous species. These results support hydraulic limitations to gas exchange, and suggest that wood anatomy and xylem cavitation vulnerability may be indicators for predicting gas exchange of trees in semi-arid regions in response to varying atmospheric conditions.
Key words: water relations, gas exchange, urban forest