POST-FIRE REVEGETATION IN ACACIA SPP. SHRUBLANDS IN SIERRAS OF CÓRDOBA, CENTRAL ARGENTINA

Abstract

In the Sierras Chicas of Córdoba (Argentina), Acacia aroma and A. caven form substitution shrublands in sites where fire is the main factor modifying the landscape. The evaluation of the post-fire dynamics is important in order to study the dynamic of vegetation recovery, as an ecological strategy for natural recovery of fire-prone environments. The objective of this work was to identify the colonizing species in the affected site, its colonization mechanisms and velocity of recovery in the disturbed environment, as well as the ecological succession in the short term. Revegetation was studied in a burned woodland originally dominated by Acacia aroma and A. caven. The Quadrat method was applied over 50 x 50 cm sectors under the canopy of Acacia spp. species, and individual species coverage was measured in three moments after the fire in two topographic positions (i.e hill and half hill). Plant cover recovery was quick because of the occurrence of low intensity wildfire and the adequate provision in soil organic carbon, nitrogen and phosphorous content compared to control. Dominant species found (Acacia aroma, Acalypha communis, Cantinoa mutabilis, Cyperus rotundus, Nothoscordum gracile, Parthenium hysterophorus L., Setaria spp. y Sida argentina) had good ability for resprouting and germination due to the therophyte, hemicriptophyte and geophyte life form. They possess good ability for competition by rapid biomass production after disturbances and, in some cases, by the ability of production of allelopathic substances. According to ecological interactions, some species are favored by water accumulation into the soil profile in midlands zones (A. aroma, C. mutabilis y C. rotundus), while other species (Setaria spp., P. hysterophorus y S. argentina) would have better differential development in highlands, under the effect of lower total coverage.