Growth resilience of Austrocedrus chilensis to drought along a precipitation gradient in Patagonia, Argentina

Abstract

Extreme weather events are increasing in frequency and magnitude due to climate change. In this context, the impacts of droughts on forest mortality will increase making it more relevant to determine the resilience of native forests to drought. Austrocedrus chilensis is an endemic conifer adapted to dry-mesic environmental conditions in the Patagonian Andes. We sampled 9 sites along a 60 km transect encompassing the West-East precipitation gradient (2000–500 mm yr− 1 ) located at Nahuel Huapi National Park (Argentina). We measured tree-ring widths of living and dead trees growing in three forest types (mixed, closed, and open) along the precipitation gradient. We characterized extreme droughts using six stations precipitation series and CRUTS v4 temperature records. The extreme summer drought of 1943–44 appears to have influenced the growth patterns of A. chilensis over the next 30 years in all trees along the precipitation gradient. Based on basal area increments before, during, and after ten extreme droughts, we calculated the growth resilience components: resistance (Rt), recovery (Rc), and relative resilience (rRs) for living and dead trees. The Rt and rRs show low values (index < 1) whereas Rc was higher (index > 1) for all trees and forest types. Differences among forest types were only significant for Rt. In turn, living and dead trees showed significant differences for Rt in closed forests. Our results also indicate that A. chilensis trees with a high capacity to maintain growth rates during droughts (resistance) in wetter environments (mixed and closed forests) have a larger chance of survival than in drier forests. Consequently, an increase in the intensity and frequency of drought events suggested by future climate change scenarios could affect the carbon reservoirs related to Patagonian forests and their ecosystem services to people.