Response of woody species to different fire frequencies in semiarid rangelands of central Argentina

The aim of the study was to assess the effect of different controlled fire frequencies on cover, density and mortality of the most common woody species in semiarid rangelands of the Caldenal district of central Argentina over a 20-year period. The study comprised three fire treatments: (1) high fire frequency (controlled burns every 3-4 years; HFF); (2) low fire frequency (controlled burns every 8 years; LFF); and (3) unburned control. Repeated burns of moderate intensity, regardless of frequency, reduced the cover and the individual height and canopy area of the most common woody species. Their density was barely affected and the mortality rates were negligible with woody species producing new sprouts after each burn. The woody species under study had a similar response to the high-and low fire frequency treatments. A controlled burn every 3-4 years, permitted the control of woody species cover, height and canopy area, which in turn may favour the production of desirable perennial grasses. The important managerial implication is that the repeated use of controlled fires of moderate intensities in the autumn, given appropriate grazing management, is likely to be essential to maintain these rangelands.