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Abstract Detail


Mitchell, Denise [1], Santiago, Louis [2].

Coordination of Drought and Heat Tolerance in Woody Species Across Ecosystems.

Widespread drought-induced mortality has been observed in woody plants across ecosystems in recent years. Extreme heat events often accompany drought, but whether heat and drought tolerance are coordinated in leaves is unknown. The objective of this research is to characterize the coordination of drought tolerance and heat tolerance in deciduous and evergreen woody species from three distinct ecosystems, Mediterranean type shrublands, mixed evergreen forest, and desert, that differ vastly in both mean annual precipitation (MAP) and mean annual temperature (MAT). We ask the question, “Does there exist a statistically significant correlation between drought tolerance and heat tolerance within ecosystems, across ecosystems and within the leaf growth habits, deciduous and evergreen?” To answer this question, a young mature leaf was collected from approximately five individuals of 20 woody species during the wet season (Feb. 2020/2021) and the dry season (July 2020), to account for plasticity and intra-specific trait variation. Using 6 – 8 species from each ecosystem, we characterized drought tolerance as leaf turgor loss point (πtlp) using the rapid assessment method, and heat tolerance using chlorophyll a fluorescence to determine photochemical efficiency decline with increasing temperature. Dry season measurements showed stronger relationships than wet season measurements, demonstrating that leaf heat and drought tolerance were statistically related across all species (R-squared = 0.26, p = 0.02). This result suggests that there may exist suites of traits for tolerating heat and drought that are conserved across ecosystems, regardless of the distinctly different precipitation and temperature regimes. Further, the data suggests a tighter correlation between drought tolerance and heat tolerance exists in the evergreen leaf growth habit (R-squared = 0.82, p = 0.03), suggesting that the physiology is driving selection over ecological parameters. This relationship was not significant among deciduous species likely because deciduous species lose their leaves during the unfavorable season, mitigating their exposure to stress. We attest that by assessing the correlation of drought tolerance and heat tolerance of woody species across three distinct ecosystems we may gain a deeper understanding of the physiological, morphological, and biochemical traits that enable the plant to sustain respectable water potentials and minimize heat damage to ultimately gain enough carbon to survive stressful periods of drought and extreme heat.

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1 - 4198 Sunnyside Drive, Riverside, CA, 92506, United States
2 - 3141 Terrace Drive, Riverside, CA, 92507, United States

Drought Tolerance
Heat Tolerance
Turgor Loss Point
Chlorophyll a fluorescence
Woody Species.

Presentation Type: Oral Paper
Session: ECOPH2, Ecophysiology II
Location: /
Date: Tuesday, July 20th, 2021
Time: 2:45 PM(EDT)
Number: ECOPH2017
Abstract ID:59
Candidate for Awards:Physiological Section Best Paper Presentation

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