Dendroclimatological Analysis of the Impact of Recent Temperature and Snow Trends on Podocarpus lawrencei in the Australian Alps

Abstract

Alpine and sub-alpine ecosystems are particularly vulnerable to the impacts of anthropogenic climate change. Consequently, understanding the impact of current temperature and snow trends in these areas is vital in predicting the longer-term impacts of climate change. The Australian Alps contain a diverse array of ecosystems and species, which are especially susceptible to climate change due to the low elevation of the mountain range in comparison to alpine areas elsewhere. The main aims of this study were to use dendrochronological methods to identify the sensitivity of Podocarpus lawrencei (mountain plum pine) growth to variability in air temperature and snow depth throughout the Australian Alps and to determine whether recent temperature and snow depth trends are impacting long-term growth of the species. Tree-ring width data was obtained from full stem cross-sections from Mt Bimberi and Mt Murray in the ACT, Mt Jagungal in NSW, as well as Falls Creek and Mt Buller in Victoria. These tree-ring width series were then objectively crossdated and standardised to create site-level ring width chronologies. Multiple dendrochronological standardisation methods were used to create chronologies that emphasised short-term and long-term tree-ring width variability. These chronologies were then integrated using principal component analysis to generate regional chronologies that emphasised common variability trends. The chronologies comprising the first and second principal components revealed correlations with snow depth and temperature respectively. More importantly, correlation between the principal component chronologies and these climate variables weakened significantly over the latter part of the twentieth century. In addition, a significant positive temporal trend is evident in tree-ring width during the same period. This trend suggests that recent trends in temperature and snow that are potentially linked to anthropogenic climate change, may be impacting upon P. lawrencei throughout the Australian Alps. Show more