Evaluación de prácticas de desmonte selectivo y clausuras temporales en sistemas degradados del Chaco árido (Argentina)

Agro-silvopastoral systems have a very important agroecological function in the world, especially in marginal areas. In this paper two silvopastoral treatments were evaluated over four sites from Chancani and Los Medanitos, Pocho Department, Cordoba (Argentina); they were evaluated by applying manual selective clearance and closures (CD), comparing them with nearby sites without clearance and closure (CSD) and controls (T). Type and amount of forageable biomass, sprouts and trees were evaluated to define the baseline. Soil (0-15 cm) was sampled and the variables organic carbon (Corg), total nitrogen (Nt), C/N relation and nitrogen of nitrates (N-NO3) were determined. A design of divided parcels was applied and, with the obtained data, a variance analysis was made, comparing between treatments. The results (three years of evaluation) showed higher forage productivity values in CD compared to CSD and T. The closure effect was evidenced also in the indicator species ratio and in the sprouting increment. In CD and CSD changes were evidenced in the pasture quality, rising the proportion of desirable species compared to Intermediate and undesirable species. Besides, the percentage of bare soil was reduced compared to T. Forestry regeneration increased in the deforested sites (CD), compared to CSD+T. The Corg, Nt y C/N analyzed variables did not show important variations depending on treatments and years. It is shown that in CD sites there is a rise (although not significant) in soil N-NO3 values by the second year after the clearance was applied.