Abstracts Biological Sciences

Rangeland revegetation in the Chihuahuan Desert

by Jason C. Wrinkle

Reclamation of drastically disturbed sites in semi-arid regions with a dependable vegetative cover assists in controlling excessive erosion and assists in soil stabilization. Following waste burial the Texas Low-level Radioactive Waste Disposal Authority must revegetate the earthen disposal caps. In 1997 a revegetation experiment was initiated to determine the beneficial uses of three seed mixtures (containing varied percentages of Lehmann lovegrass, blue grama, plains bristlegrass, green sprangletop, and sand dropseed) and three ground covers (bare ground, gravel, and temporary erosion control mat) with and without supplemental irrigation to revegetate the disposal caps. Following the 1997 experiment it was concluded that seed mixture two (20% of each species) outperformed seed mixture one (50% Lehmann lovegrass) and seed mixture three (80% Lehmann lovegrass). Also the use of a ground cover was beneficial to planting dates during the hot summer months and the soil erosion benefits are unquestioned. Therefore the use of a ground cover is advantageous regardless of planting date. Additionally the use of irrigation increased seedling emergence and end-of-year biomass under all conditions tested. Using the 1997 conclusions, the 1998 experiment focused on the use of supplemental irrigation. In particular, various rates and patterns were tested, in order to determine the most efficient treatment. One seed mixture (mixture two) and one ground cover (temporary erosion control mat) were used. The temporary erosion control mat was chosen due to its soil erosion reduction capabilities and easy installation. Nine irrigation treatments were tested during the 1998-growing season on two planting dates (June 18 and July 29).