Module 2 PROXIES
Adressed key deliverable: To perform integrated regional extreme event impact and vulnerability assessments through dendroclimatology and other proxies. Tree ring research activities as well as historical descriptions are key assets to reconstruct climate, climate change and extreme event impacts on vegetation and to perform regional vulnerability assessments. The activities will complement the model-based impacts analyses by extensive ‘ground-truth’ through dendroecological and historical data. The results will be most relevant in paleoclimatology to interpret the divergence effect, a reduced sensitivity of tree rings and other indicators to temperatures, likely related to extreme conditions.
Impact of climate and climatic extremes on tree growth
Tree-rings are among the most abundant data sources available for the characterization of vegetation response to climate and climatic extremes. Using tree-ring data for reconstructing past climate and evaluating the influence of current climate on tree-growth is among the most prominent uses for this data stream and is backed by a vast amount of literature. There are, however, a couple of unresolved issues. In the context of forest ecology and forest management, these comprise the differential climate and drought response of different species and provenances, as well as the influence of other intrinsic factors on the modification of the climate response at the level of individual trees. In the context of climate reconstruction, unresolved issues include the influence of extremes on the general climate/growth coupling - as a possible source for divergence - and methodological concerns regarding the preservation of variance in the proxy records.
E3 has focused on the characterization of species- and provenance specific response patterns to climate and drought extremes, the detection of possible divergence by the application of adequate statistical methods and the characterization of tree-ring growth on intra-annual time scales.
Influence of climatic extremes on phenology
As a second important data stream for vegetation response to climate and climatic extremes, E3 is analyzing available phenological observations to assess a possible divergence effect in phenological observations, and trends in the risks of late spring frost associated with climatic changes.