Grazing ecology and the conservation of the Caldenal rangelands, Argentina

Abstract

Grazing by domestic livestock in the Caldenal rangelands has been threatening the ecological balance of this unique biome located in the semiarid zone of central Argentina. The aim of this review was to describe and explain the floristic changes observed in grazed rangelands in the southern Caldenal, discuss management alternatives for the conservation of desirable plant communities, and identify gaps in current knowledge of this distinctive ecosystem. Grazing-induced modification in the species composition entails the replacement of palatable grasses by unpalatable grasses and/or woody plants. Coarse grass and shrub encroachment represents discontinuous stable changes that lead to undesirable regimes in terms of functionality of primary ecological processes, species diversity, carrying capacity, and the economic productivity of livestock operations. Recovery of the desirable regime dominated by palatable grasses requires active restoration technology, which is often constrained by climatic and economic factors. Conservation of the regime dominated by palatable grasses calls for flexible stocking rates and intermittent grazing in replacement of current fixed stocking rates and continuous grazing. However, there is a basic need for more research related to restoration alternatives, grazing management, and for the development of simulation models to encompass the complexity of the system and assess the ecological and economic consequences of different management options of the southern Caldenal rangelands.