Abstract Detail

The impact of climate change on plant physiology in natural and agricultural systems

Aparecido, Luiza Maria [1], Naylor, Kallika [2], Werner, Isabella [3], Braithwaite, Raven [1], Schmidt, Ella [4], Das, Jnaneshwar [1], Throop, Heather [1], Hultine, Kevin [5].

Thermal stress impacts urban desert plant physiology.

In arid regions where episodic heatwaves regularly occur, urban heat islands pose a major threat to human and environmental health, requiring city managers to develop strategies to mitigate the effects of excess heat. Urban vegetation is known for mitigating some of these threats by cooling the local surroundings through shade and evapotranspiration. However, choosing the appropriate tree species remains a challenge, as urban planners have little information on species’ cooling capacities (i.e., shade intensity and area, water use) relative to water resources that are becoming more limited in many urban locations. Here, we quantified the species-specific cooling effect of 14 tree species (native and exotic) commonly found in Phoenix, AZ, USA, one of the world’s warmest metropolitan areas. Specifically, we investigated 1) how plant water use and shade projection differed across species; and 2) how these parameters changed from spring to mid-summer when temperatures regularly exceed 40°C. We measured leaf stomatal conductance (gsw), leaf and whole-plant transpiration (Et), coupled with measurements of canopy temperature, canopy volume, and microclimate. Measurements were taken from mid-Spring and extended through pre-Monsoon and Monsoon summer (March-July 2021). Contrary to popular belief, exotic tree species did not significantly transpire more than native species on average or across seasons. While gsw declined as vapor pressure deficit and leaf temperature increased with summer conditions, an exception was observed in June 2021 in which both gsw and Et substantially increased after a heatwave event. That response was not observed in July 2021 due to a subset of species suffering from leaf thermal damage and possible loss of xylem conductivity. Eleven of the 14 species increased midday Et, contributing to enhanced canopy cooling, while the remaining three species suppressed water loss in response to thermal stress (e.g., stomatal closure or thermal damage to photosynthetic tissues). Importantly, species that were highly susceptible to thermal stress had reduced canopy cover which compromised their capability of projecting shade during the warmest and driest period of the year. Ultimately, Pinus eldarica, Cupressus arizonica, Chilopsis linearis, Fraxinus velutina, and Searsia lancea were proven to be the best tree options for Phoenix landscaping as these species provide intermediate-full shade across seasons, relative to water use under arid conditions.

1 - Arizona State University, School of Earth and Space Exploration, 781 Terrace Mall, Tempe, Arizona, 85287, USA
2 - Arizona State University, School of Life Sciences, 427 E Tyler Mall, Tempe, AZ, 85281, USA
3 - Arizona State University, Ira A. Fulton Schools of Engineering, 699 S Mill Ave, Tempe, AZ, 85281, USA
4 - Paradise Valley High School, 3950 E Bell Rd, Phoenix, AZ, 85032, USA
5 - Desert Botanical Garden, Research, Conservation, and Collections, 1201 N Galvin Pkwy, AZ, 85008, USA

Keywords:
cooling
heatwave
water loss
Sonoran Desert.

Presentation Type: Colloquium Presentations
Number: C1003
Abstract ID:271
Candidate for Awards:None