Effects of cold conditions on the growth rates of a subtropical conifer

Abstract

Araucaria angustifolia is an endangered species that occurs in the high and cold regions of southern Brazil. This species has economic importance due to its wood and seeds, as well as playing a fundamental ecological role for the southern fauna and flora. Climate change can affect its distributional area and conservation, making it urgent to investigate the effect of climate on its development. The objective of our study was to investigate how growth rates of A. angustifolia vary in relation to interannual precipitation, temperature, frost and snowfall events. For this purpose, we used two samples obtained from each of 33 individual trees from a forest fragment on the Santa Catarina plateau, Brazil. Classical dendrochronological methods were applied for the preparation and dating of the samples. The tree rings were measured using specialized software. Superposed Epoch analysis was used to test the snow accumulation events. The climatic variables were tested by means of a correlation analysis. The Superposed Epoch analysis was used to test the snow accumulation events. Our results indicate that the species shows significant sensitivity to the climate, with the maximum and minimum absolute temperatures respectively correlated with positive and negative growth rates. Snowfall also reduced growth of A. angustifolia. Overall, extreme cold events are threats to the conservation of the species.