Dendroclimatological investigation of mainland Australia's only alpine conifer, Podocarpus lawrencei Hook.f

Developing an understanding of the impact of climate on Australia's alpine flora is critical in anticipating the impacts of climate change. The dendroclimatological analysis of the Australian mainland's only alpine conifer, Podocarpus lawrencei Hook.f., may have particular significance in this regard. Unfortunately, eccentric tree-ring widths and frequent ring wedging have previously prevented dendroclimatic investigation of the species using core samples. In this study, we overcome this limitation by using full stem cross-sections collected from individuals killed during wildfire in 2003. Despite this advantage, ring wedging and poor circuit uniformity meant that crossdating was successful for portions or complete sections of only 56% of samples. Nevertheless, we constructed a crossdated chronology spanning 114-years (1888–2001) – the first for P. lawrencei. Climatological analysis revealed significant positive correlations with air temperature during spring of the growing season and significant negative correlations with monthly and seasonal snow variables as well as spring precipitation. Further analyses using 50-year moving windows reveal that responses to minimum air temperature and precipitation are unstable and periodically non-significant. Nevertheless, whilst correlation with mean maximum temperature during October and November (spring) of the growing season as well as the seasonal integration of snow cover exhibits variability throughout the analysis period, this variability appears to be independent of trends in both mean temperature and snow cover. We conclude, given the species longevity, its sensitivity to climate as well as the availability of sample material throughout the Australian Alps, that P. lawrencei holds a hitherto unrealised potential for climate reconstruction in south-east Australia. Further dendrochronological investigation of the species is currently underway throughout the Australian Alps to exploit this potential.