CONICET | Buscador de Institutos y Recursos Humanos

MILAGROS RODRÍGUEZ CATÓN; SALVADOR CALI; MARIANO S. MORALES; RICARDO VILLALBA; BLAZINA P; MARIANO MASIOKAS; ANA M. SRUR; ALBERTO RIPALTA; IGNACIO A. MUNDO

Lugar:

Mendoza

Reunión:

Conferencia; Third American Dendrochronology Conference-Ameridendro; 2016

Institución organizadora:

IANIGLA-CONICET

Resumen:

Although reductions in tree growth have previously been associatedwith forest decline, comprehensive efforts tounderstand these relationships are rare. Based onring-width variations, we determine the influence of climatic fluctuations on theonset and temporal evolution of Nothofagus pumilio growth decline in thePatagonian Andes. We sampled 11 sites showing crown dieback symptoms. Regionalpatterns of Basal Area Increment (BAI) were derived from 294 Nothofagus treesin a 500-km latitudinal transect along the forest-steppe ecotone in northernPatagonia. Two BAI patterns show sustained negative trends over the last 3 to 6decades. Tipping points in growth trends are associated with two extremedry-warm climate events in spring-summer of 1942-1943/1943-1944/1944-1945 and1978- 1979. Both severe droughts were preceded by up to 10 years of wet periodsthat promoted above-average tree growth. We concluded that severe droughtsoccurring after wet periods trigger the decline of large, dominant N. pumiliotrees with high rates of growth. The coincidence between major changes inregional growth with two of the most severe droughts in the instrumentalrecords shows that climatic variations over northern Patagonia synchronize theonset of forest decline at a regional scale. Since these dry-mesic N. pumiliosites will face more severe droughts in the 21st century, as suggested byfuture climate scenarios, the areas affected by forest decline would increasesubstantially.