Rewilding of large herbivore communities in high elevation Puna: geographic segregation and no evidence of positive effects on peatland productivity

Abstract

During the past decades, the Argentine Puna (a subtropical high elevation desert of c. 14 million hectares) has been going through a process of “rewilding” of large herbivore communities. In response to rural population outmigration and resulting livestock reduction accompanied by protection measures, large wild herbivores such as vicunas increased. To explore the ecological consequences of this transition, we analysed the spatial patterns of wild herbivores and livestock in relation to human settlements, and we estimated the changes in vegetation productivity of peatlands, using NDVI derived from MODIS satellite images between 2001 and 2012. Peatlands are key ecosystems in high elevation deserts; they regulate water and carbon fluxes and provide most forage for livestock and wildlife. A field survey of 50 peatlands revealed that travel time from human settlements was positively correlated with the wild herbivore abundance, and negatively correlated with livestock abundance (especially sheep and goats). Thus, it is a good indicator of livestock use. At the regional scale, after controlling for the physical and climatic variables of the 8134 peatlands, accessibility from human settlements explained less than 0.1% of mean and interannual NDVI variability. These results provide no evidence of livestock-induced degradation. Furthermore, likely due to rainfall increase, peatlands showed an overall positive NDVI trend between 2001 and 2012, but isolated peatlands showed comparatively more negative NDVI trends during the same period, possibly associated with increased wildlife herbivory. Similar rewilding processes could occur in many mountain regions undergoing decreasing human population and marginal land uses. Our study suggests that traditional management could contribute to the productivity, stability, and resilience of peatlands.