Using Soil-Plant-Atmosphere Continuum Modeling to Evaluate Drought Tolerance in the Urban Environment
Start Date
3-16-2026 4:00 PM
End Date
3-16-2026 6:00 PM
Abstract
Global climate change expansion in the past few years is affecting the urban environment in the Pacific Northwest. The Mediterranean climate, combined with climate change, is making conditions more severe for plant function and ecosystem services through increasing soil moisture limitation. As a result, identifying the changes in plant physiological processes caused by soil moisture limitation is important for conservation and restoration initiatives.
This research uses the Photo3 model to quantify gas exchange, plant water use, and water use efficiency under urban environmental conditions in Portland, Oregon. Meteorological data required for the model simulation were obtained from the weather station located at the Portland State University Greenhouse. Plant physiological measurements and model parameterization were conducted on Punica granatum (Pomegranate), a C3 perennial species known to exhibit relatively high drought tolerance compared to many cultivated crops. Control and drought conditions were generated by scaling half-hourly rainfall magnitudes from the weather station to represent 100%, 75%, and 50% of baseline precipitation.
The results show declines in soil moisture and increasingly negative leaf water potential, indicating constrained water availability and reduced hydraulic flux through the plant. Despite these changes in plant water use, photosynthesis rates remained unchanged while transpiration declined modestly, suggesting active regulation of water loss through stomatal control. This decoupling of carbon assimilation from transpiration indicates a capacity for pomegranate to maintain carbon gain under moderate rainfall by reducing water use.
Subjects
Climate Change, Plant ecology
Creative Commons License
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Using Soil-Plant-Atmosphere Continuum Modeling to Evaluate Drought Tolerance in the Urban Environment
Global climate change expansion in the past few years is affecting the urban environment in the Pacific Northwest. The Mediterranean climate, combined with climate change, is making conditions more severe for plant function and ecosystem services through increasing soil moisture limitation. As a result, identifying the changes in plant physiological processes caused by soil moisture limitation is important for conservation and restoration initiatives.
This research uses the Photo3 model to quantify gas exchange, plant water use, and water use efficiency under urban environmental conditions in Portland, Oregon. Meteorological data required for the model simulation were obtained from the weather station located at the Portland State University Greenhouse. Plant physiological measurements and model parameterization were conducted on Punica granatum (Pomegranate), a C3 perennial species known to exhibit relatively high drought tolerance compared to many cultivated crops. Control and drought conditions were generated by scaling half-hourly rainfall magnitudes from the weather station to represent 100%, 75%, and 50% of baseline precipitation.
The results show declines in soil moisture and increasingly negative leaf water potential, indicating constrained water availability and reduced hydraulic flux through the plant. Despite these changes in plant water use, photosynthesis rates remained unchanged while transpiration declined modestly, suggesting active regulation of water loss through stomatal control. This decoupling of carbon assimilation from transpiration indicates a capacity for pomegranate to maintain carbon gain under moderate rainfall by reducing water use.