Plant and water-level dynamics in an east texas shrub/hardwood bottomland wetland

Abstract

Plant distribution and layering were analyzed from four line transects across aninehectare shrub swamp and adjacent hardwood bottomlands, and water fluctuations and hydroperiod were assessed via six wells and staff gauges. Vegetational transition from deep to shallow water was buttonbushCephalanthus occidentalis, water elmPlanera aquatica, overcup oakQuercus lyrata, water oakQ. nigra, willow oakQ. phellos, and several other hardwoods intermixed at less frequently flooded elevations. A past die-off of overcup oak and other vegetational changes suggest that a single event or a series flooding events occurred during the growing season. Vegetative change included rapid establishment of herbaceous vegetation in shallow, open are as after overstory die-off, followed by gradual invasion of water elm. Further opening in adjacent bottomland woods is resulting from windfall of shallow-rooted oaks. Impoundments for green-tree reservoirs or other water-level modifications should be based upon an understanding of local plant succession since slight changes in water regime may modify plant species or cover-water patterns and seriously impact the wetland community. Where possible, natural water regimes should be preserved; where this is impossible due to watershed modifications, such regimes should be documented and duplicated by use of the most simple possible management system to avoid endangering natural plant communities.