Stabilized Forage Guarantee System: defining a forage storage capacity to stabilize livestock production in vulnerable ecosystems

Abstract

Livestock production in semi-arid areas has been unpredictable due to of climate variability, mainly rainfall. This study aims to simulate rangeland production variability affected by rainfall over time and relate it to an adjusted carrying capacity, using forage stock to maximize the potential of production of the system to a specific guarantee level. Regression analysis of forage biomass against rainfall were performed for ecological sites in Brazilian semi-arid to generate probability distribution curves for the historical rainfall for each location using Monte Carlo approach. The forage biomass variability estimated over time was used as input to the model. The system optimizes forage use at a sustainable stocking rate and uses forage surpluses in good years to fill deficits during adverse years, due to a certain level of guarantee. As a rule, the smallholder farmers would need to maintain a storage of around 1,500 kg ha^-1 of DM of forage to maintain an adjusted carrying capacity of 0.11 animal units ha^-1, with a guarantee of 95% in the long term, stressing the forage storage capacity as a central component of the model. Since farm size influences the forage production capacity and, mainly from the forage stock, recommendations to cope with this paradigm are suggested.