Seed reserves in the tailwater pits of playa lakes in relation to waterfowl management

Abstract

Seed reserves were monitored in the tailwater pits of 10 playa lakes on the Southern High Plains of Texas. These deep, steep-sided pits are excavated by famers to store water for irrigation and livestock. Unfortunately, pits partially drain the productive littoral zones of playa basins and thus, often have a negative effect on, wetland wildlife. We constructed experimental pits with step-like terraces on one side to create artificial liuoral zones in playa pits. Post-excavation seed numbers were near zero, but rainwater and irrigation tailwater later washed large numbers of seeds into the pits from the playa basins. The resulting seed bank was large and diverse enough to produce dense stands of wetland vegetation in all parts of the pits. Terraces produced more (P 0.05) in deep areas during winter, but seeds were depleted (P<0.05) on the terraces. All pits will produce wetland vegetation each year under almost any water regime because of the variety of seeds present.