| Flooding and Hurricane Effects on Tree Growth in the Atchafalaya Basin, Louisiana |
NO PRESENTATION AVAILABLE
Thomas W. Doyle and Richard H. Day doylet@usgs.gov
U.S. Geological Survey, National Wetlands Research Center, 700 Cajundome Blvd., Lafayette, LA, 70506
Abstract
Flood and hurricane disturbance are primary agents of change driving forest establishment and destruction in the alluvial reaches of the Atchafalaya Basin of coastal Louisiana, USA. Flood conditions bring both increased hydroperiod and oxygenated, nutrient‐enriched river water to backswamp settings that can augment or suppress forest and tree growth depending on the hydrogeomorphic setting, residency time, and tree species. Experimental results and tree ring data from the lower Atchafalaya Basin in Louisiana have verified that tree species and forest communities generally increase growth potential under nutrient‐enriched riverflow. Studies of the effects of wastewater discharge into swamp forests also demonstrate enhanced forest production with higher nitrate concentration. Tree‐ring records from multiple species chronicle past floods and hurricane events that alter stand density, soil amendments, and water quality sufficiently to cause abrupt growth in ring size and behavior in negative and positive ways. Release episodes in the tree ring record are mostly tied to recurring hurricane events and past logging harvests. Overall, the trees and forests of the Atchafalaya Basin are fairly young, usually less than 60 years of age, and susceptible to recurring disturbance from floods and hurricanes that contribute to high forest turnover. |
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