Presentation Type
Presentation - Campus Access Only
Faculty Mentor’s Full Name
Anna Sala
Faculty Mentor’s Department
Division of Biological Sciences
Abstract / Artist's Statement
Drought-induced mortality is an increasingly important driver of forest loss across the western U.S. as the severity of drought intensifies under global climate change. Under drought, the water column in the xylem, the tree’s water transport system, encounters increasing tension, potentially leading to embolism and interruption of water transport. Repeated embolism can ultimately lead to hydraulic failure and eventual drought-induced mortality. Studies in poplar have shown that depletion of stored non-structural carbohydrates (NSC), which is common under drought, increases their vulnerability to xylem embolism. However, few studies have mechanistically characterized this relationship in conifer species or in naturally occurring field populations. Therefore, it remains unknown if NSCs play a functionally significant role in determining vulnerability to embolism and overall drought mortality risk. In this study, I will test whether NSCs influence vulnerability to embolism in naturally occurring Pinus ponderosa saplings. To test for an NSC effect, I will leverage an ongoing experiment where sapling NSC pools will be manipulated relative to controls (i.e. non-manipulated) by shading trees and simulating drought conditions. Vulnerability to embolism curves will be generated on branches from five trees per treatment using the air injection method: stems will be subjected to progressively increasing tensions to induce embolism, and at each tension I will measure the hydraulic conductivity. For each treatment, I will use NSC concentration data to test whether NSC depletion increases vulnerability to embolism based on vulnerability to embolism curves. This study will add to the literature on the dynamic roles of NSCs in regulating drought tolerance and may provide insights for advancements in modeling and predicting drought-induced mortality risk in forests.
Category
Life Sciences
Non-Structural Carbohydrate Depletion May Increase Vulnerability to Embolism in Drought-Stressed Ponderosa Pine Saplings
UC 331
Drought-induced mortality is an increasingly important driver of forest loss across the western U.S. as the severity of drought intensifies under global climate change. Under drought, the water column in the xylem, the tree’s water transport system, encounters increasing tension, potentially leading to embolism and interruption of water transport. Repeated embolism can ultimately lead to hydraulic failure and eventual drought-induced mortality. Studies in poplar have shown that depletion of stored non-structural carbohydrates (NSC), which is common under drought, increases their vulnerability to xylem embolism. However, few studies have mechanistically characterized this relationship in conifer species or in naturally occurring field populations. Therefore, it remains unknown if NSCs play a functionally significant role in determining vulnerability to embolism and overall drought mortality risk. In this study, I will test whether NSCs influence vulnerability to embolism in naturally occurring Pinus ponderosa saplings. To test for an NSC effect, I will leverage an ongoing experiment where sapling NSC pools will be manipulated relative to controls (i.e. non-manipulated) by shading trees and simulating drought conditions. Vulnerability to embolism curves will be generated on branches from five trees per treatment using the air injection method: stems will be subjected to progressively increasing tensions to induce embolism, and at each tension I will measure the hydraulic conductivity. For each treatment, I will use NSC concentration data to test whether NSC depletion increases vulnerability to embolism based on vulnerability to embolism curves. This study will add to the literature on the dynamic roles of NSCs in regulating drought tolerance and may provide insights for advancements in modeling and predicting drought-induced mortality risk in forests.