The Potential of Tree Rings in Eucalyptus pauciflora for Climatological and Hydrological Reconstruction

We investigate the causes of variability in a tree‐ring chronology comprising data from Eucalyptus pauciflora Sieb. Ex. Spreng. at the alpine treeline on the Kosciuszko Plateau in New South Wales, Australia. Following verification of crossdating in a subset of the available data, we found that ring width correlates significantly with net radiation, precipitation and mean minimum and maximum air temperature during the preceding winter and spring of the growing season. Our results for spring are consistent with the impact of climate on tree growth in alpine woodlands reported in previous studies. Analyses of snow‐depth data revealed negative correlations with ring width throughout winter and spring. Our results indicate that low temperature and high precipitation during winter negatively affect the growth of E. pauciflora by prolonging spring snow cover. Ring width also correlates significantly with an index of soil dryness and flow in rivers with their headwaters in the Kosciuszko plateau. Given the apparent sensitivity of our chronology to climate and snow conditions, our results suggest that tree‐ring chronologies comprising data from E. pauciflora at the alpine treeline have potential for climatological and hydrological reconstruction in southeast Australia.     

The Dendroecological Potential of Eucalyptus Camaldulensis Dehnhardt (River Red Gum) from the Barmah Forest,Victoria, Australia

The study of tree rings has been used for over 100 years to inform climatic and geomorphological reconstructions. In mainland Australia, no tree species are currently recognised as providing reliable sources for such studies over extensive areas. Eucalyptus camaldulensis is a widely growing species with a growth pattern that is closely linked to high levels of available moisture, such as that associated with floods. The species therefore has the potential to provide palaeoclimatic information that may be of use in hydrological and geomorphological studies. This study initially examines the microstructure of samples of E. camaldulensis taken from the Barmah Forest to assess the applicability of the species to dendroecological investigation. It is found that samples of the species exhibit ring‐like structures, although there are areas of the samples that contain zones of growth without clear ring boundaries. The patterns of growth rings and zones are found to be common to many trees at a site, although the level of variability of pattern from tree to tree is high. Options for future development of the approach described here are to combine ring studies with isotopic‐based analysis to provide a combination of tree age and climatic history.     

Defining invasive alien species from the roots up: Lessons from the ‘De-eucalyptising Brigades’ in Galicia,Spain

Social and cultural perspectives are increasingly considered in the literature on invasive alien species (IAS), after decades of being underexplored. However, within this growing body of research, there is little investigation into the role and knowledge of everyday rural and environmentalist networks in defining and engaging with or against the expansion of IAS. This paper contributes to debates on the political and spatial implications of this concept, through a critical examination of the bottom-up initiative of the ‘De-eucalyptising Brigades' (Galicia, Spain), which aims to remove eucalyptus trees from community-based property lands. A survey of participants of this movement paired with semi-structured interviews show the relevance of social-cultural dynamics in defining IAS. Our results also show how investigating activism against forestry involving a potential IAS sheds light on the everyday conflicts around who defines IAS and how they are defined.