Get reliable science

Severe droughts and past abuses by overgrazing are present in part or most rangelands and sometimes drastic manipulations of the rangeland ecosystem are required or desired to reestablish herbaceous vegetation. In the 1980´s permits were issued to the state of Sonora in Mexico for clearing existing vegetation by bulldozer followed by the seeding with buffelgrass, with the intention of increasing productivity of forage for livestock. Seeding cleared areas with monocultures of introduced species negatively affects habitat quality for important wildlife species; and they often expand well beyond sites where they have been seeded and replace native vegetation. Our objectives were to evaluate vegetation diversity 25 years after clearings, and to determine the effects of aeration on the invasion of exotic grasses on previously disturbed and undisturbed desert scrub vegetation. The study was conducted in the southern end of the Sonoran Desert in the state of Sonora, Mexico. The experimental design was a randomized complete block with three replications. Treatments evaluated were: aeration, aeration on previous cleared area 25 years before, cleared area 25 years before, and control. Response variables included canopy cover of woody plants, canopy cover of herbaceous plants and native species richness. The indicators of aeration as management practice on the southern end of the Sonoran desert reflect an increase in herbaceous vegetation.