Flooding and saltwater intrusion: Potential effects on survival and productivity of wetland forests along the U.S. Gulf Coast

Abstract

The predicted global warming trend and resultant sea-level rise will increase inundation and salinity along coastal regions worldwide. As water level increases, saltwater encroaches farther inland in many coastal areas. Responses of Gulf of Mexico coastal tree species to increased flooding and saltwater intrusion is evaluated. A review of investigations which address changes in morphological characteristics and carbon assimilation rates under short-term flooding and/or salinity conditions is presented. The combination of flooding and salinity causes foliage damage and substantial reductions in carbon assimilation. The morphological response and reductions in gas exchange rates are closely associated with increases in salt levels. Exposure to salt concentrations greater than 50 mol m −3 (3 ppt) causes some leaf burning and decline in carbon assimilation rates of up to 84% in seedlings of some species. Results indicated that increased flooding and saltwater intrusion, a problem facing U.S. Golf Coast bottomland forests, can cause drastic reduction in net carbon assimilation, leaf burning and seedling mortality. The stress at sublethal levels can lead to weaker seedlings and, consequently, reduced survival rates, and the potential for long-term habitat changes thus limiting the existing natural range of these forests.