Global Change

Project Title:  Forest Dieback and Carbon Relations of Coastal Forests of the Southeast under Changing Climate:  Interactive Effects of Drought Severity, Hurricanes, Sea-level Rise and Coastal Management

Principal Investigator (lead): Thomas W. Doyle, Ph. D.

Introduction

Coastal forests along the Gulf of Mexico and South Atlantic are currently undergoing stress and decline from increasing tidal inundation, saltwater intrusion, and altered freshwater flow attributed to global climate change and variability.  In some places, these dying forests are referred to as “ghost” forests for the lack of live trees and many standing snags of remnant forest.  A USGS research project has been initiated to understand the pattern of tree stress and forest dieback, a process which may also be altering the way these systems either store or release carbon.

Many coastal parks and refuges are without any monitoring activity to document current and future land cover change. Research sites have been established principally on Department of Interior (DOI) lands to assess the current rate of decline and to predict the future effects of sea-level rise and climate change on tidal freshwater forested wetlands of the Gulf and Atlantic coasts.  Tidal freshwater forested wetlands under varying tidal influence in riverine and non-riverine watersheds in coastal Louisiana, Georgia, and South Carolina have been identified for detailed gradient analysis to determine the controlling environmental factors and climatic events causing forest dieback and decline. Study transects and plots have been established along freshwater to brackish gradients of these coastal watersheds to assess forest health and carbon relations with elevation and hydrologic forcing (tidal and non-tidal).  Study transects and plots have been established along Gulf and Atlantic reaches subject to different hydrogeomorphic settings, tides, drought and hurricane frequencies, subsidence rates and streamflow volumes.

Carbon sequestration processes and rates are expected to vary in different coastal environments and to undergo radical shifts in balance (loss/gain, uptake/release) at the onset and duration of forest dieback.  Forest health has been monitored on these research sites on a monthly basis to relate changes in aboveground and belowground structure, productivity, and carbon budget to changing environmental conditions including the influx and role of invasive species. Landscape simulation models are being parameterized with synthesized data from field studies and controlled experiments to predict the loss of coastal forest habitat and carbon reserves under sea-level rise and increasing drought or flood frequencies with changing climate.  Decision support tools will be developed to assist U.S. Department of Interior (DOI) land managers with designing management strategies and restoration alternatives for controlling local hydrology, recovering habitat quality, and minimizing invasive species influx of degraded environments.

Contact Information

USGS National Wetlands Research Center
700 Cajundome Blvd.
Lafayette, LA 70506
Phone: 337-266-8647
E-mail: tom_doyle@usgs.gov