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Modeling And Observing Plant Water

Speaker: Alexandra Konings, Stanford University
Series: Special Seminars
Location: Engineering Quad E225
Date/Time: Friday, May 17, 2019, 04:00:00 p.m. - 05:00:00 p.m.

Abstract:

In vegetation ecosystems, the plant response to water availability determines not only that vegetation's growth, but also the movement of water from the soil to the atmosphere through transpiration. Vegetation drought response has long been conceptualized as depending on atmospheric humidity and available soil moisture, but this ignores the role of storage and movement of water in the plants themselves (plant hydraulics) in driving plant water stress response. However, because plant hydraulics is modulated by a range of plant traits that can vary significantly even across coexisting species, understanding how and whether plant hydraulics effects transpiration at site scales and larger has proven challenging. In this talk, I will present the first site-scale study to determine the effect of plant hydraulics on modeled evapotranspiration (ET) at 24 sites with different climates and vegetation types across the world. Model-data fusion methods using observed ET and soil moisture at Fluxnet sites were used to allow optimal model parametrization. I will show that (and explain why) across a wide range of sites, accounting for plant hydraulics can significantly improve ability to model transpiration during conditions of high atmospheric water demand. In the second half of the talk, I will focus on new developments in understanding microwave remote sensing indices of vegetation water content and their potential application to plant hydraulic studies. The talk will end with a discussion of other applications of remotely sensed vegetation water content, including their use for estimating drought-driven tree mortality rates, interactions in a wide range of motions in atmospheric and oceanic flows.