Riparian Vegetation Susceptibility to Wind and Flooding Impacts of Hurricanes

Abstract

Vegetation in riparian zones of southern Texas largely consist of woody trees, shrubs, and vines that grow densely within a short distance from the river. The rich and productive nature of these environments provides critical habitat for aquatic and terrestrial species of commercial and recreational value. This study examines how woody vegetation within the Mission River riparian zone has been impacted by Hurricane Harvey that brought category 3 winds and significant flooding to the areas around the Mission River. To determine the density and the species composition of the vegetation on the riparian zone of the Mission River, vegetation was surveyed in plots that are located along the river. Density and composition of woody riparian species within these plots were determined using measurements of diameter at breast height (DBH) and compared to the findings from previous studies on the Mission River riparian zone. Based on preliminary analyses of ground and aerial images and literature on hurricane impacts to riparian zones, it is expected that Hurricane Harvey caused widespread snapping of trunks/limbs and weakened roots of larger woody vegetation. Structural compromise to woody vegetation can also reduce their ability to stabilize their crowns, resulting in a high volume of downed trees while making way for pioneering species. There are limited studies on disturbance to riparian systems that is induced by hurricanes and this research increases our understanding of how these systems respond to these types of extreme events.