This paper presents an approach to explicitly determinate optimal stocking rates based on trade-offs between guanaco density and livestock grazing intensity on rangelands of Patagonia, Argentina. As sheep farming becomes less profitable in this region, farmers and ranchers need to focus on sustainable wildlife harvesting as alternative income generation. We developed a methodology for spatially-explicit assessment and mapping of stocking rates based on tradeoffs and synergies between ecosystem services and livestock grazing intensity on rangelands. Forage use for livestock production, carbon sequestration, wildlife conservation and soil erosion are the ecosystem services and disservices evaluated over a gradient of grazing intensity. We show how rangelands stocking rate determination can be converted into a multi-objective optimization problem that can be solved using a Fuzzy Multi-Objective Linear Programing (MOLP).