Nothofagus pumilio dieback in northern Patagonia: Relationships between patterns of radial growth and crown mortality

MILAGROS RODRIGUEZ Y RICARDO VILLALBA

Uspallata, Mendoza

Encuentro; Documenting, understanding an projecting changes in the hydrological cycle in the American Cordillera; 2013

Interamerican Institute for Global Change Research

Crown dieback is frecuently observed in most Nothofagus pumilio forests located in relatively dry environments of the northern Patagonian Andes. Seven stands of N. pumilio showing external evidence of crown decline were sampled to determine the relationships between radial growth patterns and crown dieback. In each stand, Principal Component Analyses were applied to ring width and basal area increments to determine the dominant patterns of tree growth. Crown dieback was recorded for each tree using categorical classes including: severely affected (less than 25% of healthy crown), affected (26-50%), partially affected (51-75%) and healthy (more than 75% healthy crown) trees. Trees with advanced crown mortality show declining trends in ring width and basal area increments. Conversely, most healthy trees are associated with patterns of increasing basal tree-growth during the past decades. A comparison between patterns based on temporal variations in ring width and basal area increment indicates that the latter is a better predictor of N. pumilio tree health.