Climate and grazing influences on vegetation coverage across the montane subtropical deserts in South America

MARIANO S. MORALES; RICARDO VILLALBA

Grindelwald, Suiza

Workshop; 6th International NCCR Climate Summer School "Land Surface – Atmosphere Interactions in a Changing Climate"; 2007

NCCR

In the context of the past 200 years, instrumental and dendrochronological records reveal an unprecedented increase in regional precipitation during the recent decades in the Prepuna, Northwestern Argentina. Simultaneously, rural to urban migration in the recent past has reduced regional grazing impact and leaved large fields abandoned. How changes in rainfall and in the intensity of human-related activities have affected the extension and productivity of the Prosopis woodlands? At different temporal and spatial scales, rainfall appears as the major factor affecting establishment and radial growth of Prosopis woodlands. However, differences in tree-growth and survivorship are heavily affected by grazing at local scales. The increase in precipitation in combination with a reduction in grazing pressure has favored the expansion of the native woodlands of Prosopis across the region, with regional implications for the atmosphere-land interactions.