Presentation Type

Poster

Start Date

5-8-2024 11:00 AM

End Date

5-8-2024 1:00 PM

Subjects

Plants, Ecology

Advisor

Ava Howard & Gareth Hopkins

Student Level

Undergraduate

Abstract

In the Pacific Northwest, Quercus garryana (Garry oak trees) support over 627 native species. Garry oak natural habitat was originally maintained by indigenous practices but has been reduced to 5-10% of its range due to change in land management strategies. To support oak conservation, we need to understand heat and water affect the growth and physiology of this species. In this study, we created a fixed linear model of trunk cross-sectional growth with water stress (Ψ), photosynthetic water-use efficiency (δ13C), and leaf Carbon-Nitrogen ratio. We collected branch samples from the canopies of 47-64 mature Garry oaks in the Willamette Valley from 2019 to 2023 in the late summer. Samples were collected diurnally (max Ψ) or predawn (minimum Ψ). Ψ was assessed on healthy leaves from canopy samples and trunk diameter was measured sing DBH tape 1.5m above ground were assessed on-site. Samples were transported on ice to the laboratory where leaves were homogenized and assayed for δ13C and Leaf C:N ratio with spectrometry. A fixed effect linear model was used to model the relationship between trunk growth and explanatory variables. Greater δ13C predicted trunk growth. The high light exposure savannah habitat trees grew more than trees in other habitats. These results indicate that Garry oaks tolerate high levels of heat and sunlight exposure. Future conservation efforts should focus on minimizing other environmental stressors such as shade suppression to promote growth of Garry oaks to maintain indigenous habitats.

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May 8th, 11:00 AM May 8th, 1:00 PM

Relationship Between Trunk Cross-Sectional Area Growth and Water Stress in Garry Oaks (Q. garryana): A Species of Conservation Concern

In the Pacific Northwest, Quercus garryana (Garry oak trees) support over 627 native species. Garry oak natural habitat was originally maintained by indigenous practices but has been reduced to 5-10% of its range due to change in land management strategies. To support oak conservation, we need to understand heat and water affect the growth and physiology of this species. In this study, we created a fixed linear model of trunk cross-sectional growth with water stress (Ψ), photosynthetic water-use efficiency (δ13C), and leaf Carbon-Nitrogen ratio. We collected branch samples from the canopies of 47-64 mature Garry oaks in the Willamette Valley from 2019 to 2023 in the late summer. Samples were collected diurnally (max Ψ) or predawn (minimum Ψ). Ψ was assessed on healthy leaves from canopy samples and trunk diameter was measured sing DBH tape 1.5m above ground were assessed on-site. Samples were transported on ice to the laboratory where leaves were homogenized and assayed for δ13C and Leaf C:N ratio with spectrometry. A fixed effect linear model was used to model the relationship between trunk growth and explanatory variables. Greater δ13C predicted trunk growth. The high light exposure savannah habitat trees grew more than trees in other habitats. These results indicate that Garry oaks tolerate high levels of heat and sunlight exposure. Future conservation efforts should focus on minimizing other environmental stressors such as shade suppression to promote growth of Garry oaks to maintain indigenous habitats.