Climatic factors controlling radial growth and formation of wood density fluctuations in Austrocedrus chilensis in Valdivia, Chile

Abstract

Tree-ring widths and intrannual wood density fluctuations (IADFs) are sound proxies of the environmental factors that control the growth of forest tree species. In this work we evaluated the impact of climate on radial growth and IADFs formation in an Austrocedrus chilensis plantation in Valdivia, Chile. We calculated mean tree-ring chronology and the annual distribution of IADFs frequency from 20 trees, and we studied their relationships with local precipitation, temperature, and large-scale El Niño-Southern Oscillation (ENSO) and Antarctic Oscillation (AO) climatic teleconnections in the period 1975-2010. We used correlation and multiple linear regression analyses to assess the climate-growth relationships and t test for means comparison to check for differences between years with and without IADFs. We observed an inverse relationship of growth with previous summer precipitation and maximum temperature during the growing period, which suggests physiological stress for trees caused by water surplus and warm summer conditions. Years with maximum IADFs frequency were those coinciding with El Niño events, which caused dry and warm summer conditions in the study area, followed by rainy conditions in September. We did not find statistically significant relationships with AO. The interaction between local climatic conditions and ENSO variation controlled IADFs formation in the wood of A. chilensis in Valdivia.