Date of Award

5-2024

Document Type

Thesis

Degree Name

Master of Forest Resources (MFR)

Department

Forestry and Environmental Conservation

Committee Chair/Advisor

Dr. Stefanie Whitmire

Committee Member

Dr. Jamie Duberstein

Committee Member

Dr. Skip Van Bloem

Abstract

Trees in hurricane-prone areas are exposed to severe winds and flooding. We studied the physiological and structural responses of forested wetland trees in relation to wind stress. We evaluated the windfirmness of two forested wetland tree species. Baldcypress was chosen because of high survival in post-hurricane studies. In contrast, laurel oak co-occurs with baldcypress yet resists hurricane-force winds poorly. In a static winching study, we quantified the critical turning moment (Mcrit) required to topple both species. Mcrit increased with trunk diameter at breast height (DBH) and crown size. Baldcypress and laurel oak demonstrated similar Mcrit, but regression models indicate baldcypress could withstand higher wind speeds when DBH 22 cm. Many baldcypress were so flexible that when bent to the ground they did not topple. Results suggest baldcypress flexibility was important to their wind resistance. Young laurel oak showed low windfirmness. Formulas were developed to allow arborists to assess the maximum wind speed either species can survive by measuring its DBH. In order to determine the effect of common weather wind stress on tree water transport and hydraulic function, we analyzed the correlation between sap flow and wind strain from three baldcypress trees. Atmospheric vapor pressure deficit and solar radiation were measured concurrently to account for their effect on tree sap flow. There were strong relationships between sap flow, vapor pressure deficit, and solar radiation, but no relationships were found between sap flow and wind strain which suggests that under normal ambient conditions winds have little physical impact on transpiration.

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