Effect of nonprescribed fire on an Atriplex lampa community, in the Guadal plateau of Mendoza province, Argentina.

摘要

The purpose of the present study was to determine the effect of a single nonprescribed fire on species community composition, woody and herbaceous species diversity, carrying capacity, density of dominating shrubs, and their resprouting capacity after fire. For short and long-term evaluations, two sites were chosen in a private extensive cattle ranch: (1) unburned areas and (2) burned areas. The forage total cover before fire (initial stage) was 54%; this cover decreased in burned areas to 13% (1986) and to 25% (2000), mainly due to a reduction in forage shrub cover. The cover of Atriplex lampa (zampa), the dominant forage shrub, decreased from 17.0 to 0.20% in 1986 after fire, and 15 years later this value remains constant (0.33%). The same area showed a carrying capacity, expressed in hectares per large stock unit (LSU), of 10 ha LSU-1 by 1986 and 17 ha LSU-1 by 2000, whereas in unburned areas it was 7 ha LSU-1, similar to prewildfire. All selected species that had been cut, simulating the action of fire, resprouted 1 year later, except zampa. We determined that the re-establishment of zampa plants in burned areas is extremely slow. Conditions as absence of adventitious bud/root crown and drought in following post-fire years may have determined the poor recovery of A. lampa..