Charles V. Klimas

An Ecosystem Restoration Model for the Mississippi Alluvial Valley Based on Geomorphology, Soils, and Hydrology

Alternating braided and meandering stream flow regimes throughout the Quaternary Period have left a subtly complex landscape of depositional features within the Mississippi Alluvial Valley (MAV). Prior to European settlement, those variations produced tremendous spatial complexity and diversity within vast forested wetlands and extensive fire-maintained prairies and savannas, with the distribution of specific plant communities largely reflecting abiotic site characteristics such as geomorphology, soils, and hydrology. Agricultural development, river engineering, flood protection, and drainage projects over the past century have destroyed most of the natural vegetation and obscured the patterns of plant community distribution. Recent studies have established hydrogeomorphic criteria for wetland classification over a large part of the MAV. Detailed, spatially explicit geomorphology and soils data are available for the entire MAV, and hydrologic mapping has been completed in many areas. Thus, even in areas that are currently in agriculture, the tools exist to adapt the hydrogeomorphic classification and to develop maps of potential plant community distribution based on abiotic characteristics of sites. These Potential Natural Vegetation maps provide an indication of the multi-scale complexity that once characterized the MAV, and serve as planning tools for ecosystem restoration.

Baldcypress response to increased water levels, Caddo Lake, Louisiana-Texas

An investigation of baldcypress stands associated with Caddo Lake was undertaken as part of an evaluation of a proposed project to increase storage capacity of the lake. Existing stands either were impacted by or established in response to an increase in water levels that occurred seventy years ago. Examination of stand characteristics and hydrologic records indicated a predictable response to water fluctuation patterns that provided a basis for assessment of various proposed project alternatives. Baldcypress is able to persist in the face of hydrologic regime changes, but growth, reproduction, and survival are directly related to the frequency of substrate exposure. Relationships defined in this study may be useful in identifying impact thresholds and optimal water management strategies for other baldcypress stands.