Australia: The Land Where Time Began

Eucalyptus Flowering Phenology Identified as sensitive to Climate from herbarium records

Rawal et al. say flowering phenology (the study of the timing of natural events such as seasons and its effects on animals and plants) is very sensitive to climate and it has been observed that the flowering times of plants has been shifting to earlier or later as global warming progresses. Reproductive success of a species, and associated phonological events, species synchrony and composition of a community may be affected by changes in flowering times. According to Rawal et al. key insights into the impacts climate has on phenology can be provided by long-term data on phonological events. The ability to assess the impacts on plant phenology of climate change in Australia is restricted by the limited availability of data. Rawal et al. say it is necessary to use other data sources, such as herbarium specimens, to conduct studies on flowering phenology in order to address this limitation. In this study Rawal used herbarium specimens to investigate the flowering phenology of 5 dominant and commercially important species of Eucalyptus from southeastern Australia and the consequences of the variability of climate on changes of flowering phenology. The most influential factor on the flowering time of all species studied was mean temperature of the preceding 3 months relative to precipitation and the humidity of the air. A shift in the flowering time of 14.1 – 14.9 days was predicted for E. macrocarpa and E. tricarpa, while delays of flowering time of 11.3 – 15.5 days were found for E. obliqua, E. radiata and E. polyanthemos. Of these species E. polyanthemos exhibited the greatest sensitivity to climatic variables. Rawal et al. say the study has demonstrated that it is possible to use herbarium data to detect climatic signals on flowering phenology for species that have a long flowering duration, such as eucalypts. It is indicated by the robust relationship between temperature and flowering phenology that there will be shifts in flowering times under predicted climate change which may affect the success of reproduction, fitness, plant communities and ecosystems.