Sensitivity of Nothofagus dombeyi tree growth to climate changes along a precipitation gradient in northern Patagonia

SUAREZ, MARÍA LAURA; VILLALBA, RICARDO; MUNDO, IGNACIO A.; SCHROEDER, NATALIA MARIEL

TREES-STRUCTURE AND FUNCTION

SPRINGER

Lugar: Berlin; Año: 2015 vol. 29 p. 1053 - 1067

0931-1890

Understanding forest responses to climate var- iations is urgently needed for anticipating changes in forest composition and biodiversity. We use twelve tree-ring chronologies from Nothofagus dombeyi, the dominant tree at mesic-to-humid sites, to characterize climate?growth relationships along the west-to-east precipitation gradient in Nahuel Huapi National Park, Argentina. A principal components analysis indicates that a large proportion of common variance in tree growth reflects regional-scale influences of climate. Correlation functions between cli- mate and tree-ring indexes show that the critical factor regulating tree growth is spring?summer water deficit induced by above-average temperature and reduced pre- cipitation during the growing season. At high elevations, however, tree growth appears to be less sensitive to water deficit but comparatively more sensitive to warmer condi- tions. Temporal trends in climate?tree growth relationships supported the occurrence of a dominant large-scale climatic response, but also identify changes in cli- mate?growth relationships over time, primarily at wet and high-elevation sites. These variations in climate?growth relationships are interpreted as a convergence process to similar patterns in tree growth across the entire precipita- tion gradient, as wet?cool conditions at high-elevation sites turned to be less frequent due to drier and warmer years during the late twentieth century. Sampling along envi- ronmental gradients provides a comprehensive view of the potential range of responses of tree growth to climate which is not recorded using traditional dendrochrono- logical sampling at marginal, more climate-sensitive sites. The recent changes in the relationships between climate and growth highlight the vulnerability of N. dombeyi to climate changes across its entire range of distribution in Argentina.