Effect of Nonprescribed Fire on an Atriplex lampa Community, in the Guadal Plateau of Mendoza Province, Argentina

Abstract

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.

Keywords:

• burned areas
• carrying capacity
• forage cover
• resprouting capacity

The authors wish to thank Dr. H. N. Le Houérou for critically reviewing the manuscript and N. Horak for assisting in the English version.

Notes

Means in the same column followed by the same small letter are not significantly different at the 0.05 probability level, according to Duncan's means separation test. ha LSU⁻¹: hectares per Large Stock Unit. Four replicates per treatment.

Means in the same column followed by the same small letter are not significantly different at the 0.05 probability level, according to Duncan's means separation test. Five replicates per treatment.

Means in the same column followed by the same small letter are not significantly different at the 0.05 probability level, according to Duncan's means separation test. Four replicates per treatment.

Five replicates per treatment. N°: number of sprouts per plant. H: height (cm) of sprouts.