Montículos fitogéneticos en el Monte Rionegrino: su relación con incendios y pastoreo

Abstract

In the northeastern province of Rio Negro, vegetation is a shrubby grassland steppe, where plants are interspersed in a bare soil matrix forming “phytogenic mounds” dominated by shrubs, with perennial grasses, annual grasses and herbs, and microphytic crusts underneath. Fire can trigger eolic erosion through material flow from mounds to bare soil. The objective of this study was to comparae size, proportion and number of phytogenic mounds in the Monte rionegrino in situations with different histories of fire and grazing. We selected two areas excluded of grazing, one burned and the other unburned, and three grazed areas, one unburned and two burned at different momments. In each area we established five transections 20 m long, and quantity and size of mounds were registered.There are non-significant differences among situations, although the mean size of mounds in burned areas trends to be lower than grazed unburned one. In arid regions, fire would be a useful tool to avoid the shrub encroachment of the systems on having produced the redistribution of the resources of the soil, favoring grasses recruitment.