Clara María Fariña
Patagonian rangelands are affected by desertification and ecosystem services loss triggered by both climatic and anthropogenic factors, but interaction between them is already unknown. Climate change scenarios for North Patagonia predict long lasting droughts. At the same time, a controversial mob grazing system is expanding in the region without scientific-based information about its impacts. The aim of this project is to assess how long-lasting droughts affects rangelands under mob grazing with an experiment in real-field conditions, in order to generate information that help farmers making sustainable management decisions aimed at conserving arid rangelands facing climate change.
We will measure the impact of long lasting drought on rangelands affected by mob grazing systems. Particularly, we will measure the impact of 4-years reduction of annual precipitation on vegetation community composition and dynamics, following one of the climate change scenarios predictions for the region. Natural vegetation growth and phenology in North Patagonia has a marked seasonality which affects regrowth of grazed plants differently depending on the moment of the year in which grazing is implemented due to abiotic conditions, mainly precipitation and temperature. So, grazing affects more strongly rangelands which are grazed during growth season (spring) than rangelands which are grazed during latency season (autumn or winter). The consequence is that spring-grazed rangelands are under a higher pressure to be moved towards a degradation threshold than autumn/winter-grazed rangelands. Then, a long lasting drought may affect them differentially.
With information generated in this research, we will describe the dynamic of the rangeland affected by both mob grazing and drought including functional and structural traits of rangelands, taking into account reversible and irreversible transitions that can derive in different phases and/or states of the vegetal community. This information is key to determining the potential biotic or abiotic thresholds between alternative states, which refer to sustainable or unsustainable management options of arid rangelands.