VEGETATION RELATIONSHIPS TO WATER GRADIENT IN A CONSTRUCTED FRESH-WATER WETLAND NEAR BRAZORIA, TEXAS

Data on plant distribution were collected along 5 point-intercept tran sects in different water depths of a constructed freshwater impoundmen t on the San Bernard National Wildlife Refuge. Patterns of distributio n and resultant statistical correlations reflect the dominance of wate r-tolerant species and genera in the regularly flooded portion, and sp ecies that tolerate only periodic flooding in the drier reaches. Yearl y variation in rainfall and pond water levels created diverse conditio ns for plant establishment and survival, and species composition varie d considerably on transects in different water depths. Although plant richness seemed to increase over time, the establishment and subsequen t spread of cattail modified cover-water patterns and threatened struc tural diversity in deeper water areas. Potential management options in clude basin design and water management, but better life-history infor mation is essential for many of the dominant plants.