Examining Tidal Inundation and Salt Marsh Vegetation Distribution Patterns using Spatial Analysis (Botany Bay, Australia)

In predicting the impact of human disturbance on coastal wetland environments and understanding ecological response to changing intertidal conditions, there is a need to understand the relationship between species distribution and elevation dependent tidal inundation. The intent of this paper is to examine the relationship between vegetation distribution patterns and the extent of tidal inundation modelled using fine scale elevation data. Field surveys were undertaken at Towra Point, Botany Bay, Australia using high precision global positioning system (GPS) and theodolite survey to record species location and obtain horizontal mapping accuracy required for modelling localised wetland topography. Species survival and growth is governed by physiological factors that are determined by tidal inundation frequency and extent. The coupling of local tidal parameters with a detailed wetland elevation survey enabled the modelling of inundation extent. Species distributional ranges at Towra Point corresponded with modelled tidal extent, and results indicated the presence of species zonation. Fine scale representation of localised terrain features within the surface model also demonstrated the impact of altered topography on vegetation distribution patterns. The spatial analysis methods applied in this study depicted variations in inundation patterns under the differing tidal phases that influence physiological conditions throughout the wetland.