BIOGEOMORPHIC MODELS OF VEGETATION RECOVERY ON SANTA ROSAISLAND DUNES AFTER HURRICANES OPAL AND IVAN

The recovery rate of vegetation on barrier islands after hurricanes is not well understood, as the majority of studies have focused on the impact of storms on barrier islands. There is, however, a paucity of studies that quantitatively characterize vegetation recovery following hurricanes. Consequently, this research seeks to quantify changes in vegetation extent between 1994 and 2010 on Santa Rosa Island, Florida, following Hurricanes Opal and Ivan. Multispectral airborne imagery were used to analyze vegetation patterns and recovery, as dune vegetation promotes the deposition of the sand required for dune stabilization. Specifically, supervised and unsupervised classification algorithms were utilized to map vegetation. The changing patterns of vegetation distribution over time were examined in a geographic information system. Logistic growth models, usually applied to continental dune environments, were used to describe post-hurricane vegetation recovery. Preliminary results indicate that given five years of observed data, vegetation recovery has not returned to pre Hurricane Ivan extent. It is anticipated that there is a 10 year lag between beach recovery and dune recovery that is explained by vegetation recovery, and this scale dependence will be affected by high-magnitude, high-frequency disturbances.