## LSU Doctoral Dissertations

#### Degree

Doctor of Philosophy (PhD)

#### Department

Geography and Anthropology

Dissertation

#### Abstract

As sea levels rise, coastal trees are increasingly stressed by saltwater inundation, and stressed trees are ideal for studying changes in the environment through time. Dendrochronology has been used for more than a century to explain changes in past environments using tree rings. Using ring widths and stable isotopes from coastal trees, the effects of tropical cyclones and freshwater moisture availability are shown in regard to tree growth and ultimately are discussed in terms of change to the environment as a whole. Changes in tree growth as they relate to various climate parameters are measured using superposed epoch analysis, moving-window correlations, and spatial correlations.

Results show that tropical cyclones cause rapid declines in tree growth. In the first two years following large storm surges ($>$2.0 m), trees reduce growth in the stem as much as 15\%, whereas inland urban trees only show major growth declines in years following tropical cyclones with hurricane-force wind speeds ($>$33 ms$^{-1}$). For coastal trees that do not show strong tropical cyclone signals, drought conditions play a key role in growth declines. For example, tree-ring carbon isotopes show strongest spatial correlations (\textit{r}$>$0.5, \textit{p}\$

Coastal trees inundated by saltwater experience declines in growth following pulses such as drought, tropical cyclones, and anthropogenic disturbances. Future land management of coastal forests should consider changes in freshwater soil moisture availability when projecting changes in the environment. In summary, with accelerating sea-level rise and increasing tropical cyclone intensity, coastal areas can expect to see declines in tree growth.

Trepanier, Jill