Benefits of fire in shrub control in the grasslands of the monte province, Rio Negro, Argentina

Abstract

In the grasslands in the NE of Río Negro province, Argentina controlled burning or mechanical clearing are common practices to reduce the shrub layer and improve the forage supply of the grasslands that constitute the basis of extensive livestock breeding. In one area of the region, we estimated the Aerial Net Primary Productivity (ANPP) and evaluated the quality of the dominant grasses over three years in grasslands subjected to mechanical clearing and burning, through seasonal cuts of biomass and laboratory analysis. We also recorded the phenology of the dominant grasses and shrubs. We obtained higher values of Crude Protein and Dry Matter Digestibility of the grasses in spring, since they were mainly in the vegetative stage, and the differences were significantly greater in the burned site. This effect of fire would be due both to the regrowth and to the increase in the proportion of vegetative material generated by this disturbance. Mechanical clearing had no significant effects on quality, although it increased the ANPP. When analyzing phenological behavior, our results showed better conditions for livestock production in the disturbed sites, with a higher proportion of vegetative growth of the grasses and greater senescence of the shrubs.