Tree-ring anatomy to study two thousand years of climate variability and black spruce adaptations

点击翻译按钮获取中文摘要

Tree-rings are often used to reconstruct past climate and analyze forest ecosystem responses to disturbances and climate change. However, with traditional research methods we do not exploit all the information contained in tree-rings and we risk to obtain biased interpretations. The use of several tree-ring traits simultaneously and of intra-annual resolution analyses, i.e. more than one measurement per each annual growth ring, may on the other hand give us more precise and exhaustive information on climate variability and tree ecophysiology. For this research program, we will measure multiple tree-ring anatomical traits on the samples of a strategic network of tree-ring chronologies spanning the last two millennia and produced with subfossil and living black spruce trees from the Quebec boreal forest. The anatomical traits will be analyzed with intra-annual resolution and will include, for example, the tracheid lumen area, the tracheid wall thickness and the anatomical density. These traits have a specific climatic sensitivity and are directly related to water and thermal constraints that influence tree growth during the growing season. In addition, we will use our anatomical data to improve the ecophysiological modeling of wood biomass accumulation in boreal trees in the context of climate change. This research program has innovative potential because we will develop high throughput systems for anatomical measurements which are currently managed only by very few laboratories in the world. Then, we will significantly improve the climate reconstructions for the Quebec boreal region by using the most promising anatomical traits and by combining them with the tree-ring traits that we have already measured (width, density, stable isotopes of cellulose). Our intra-annual anatomical traits will also allow, for the first time, the reconstruction of past seasonal changes in humidity and temperature and the assessment of their impact on tree functioning in the boreal forest. Finally, we will use new techniques based on the inversion of the developed ecophysiological models to verify if the consideration of tree functional rules modifies the results of dendroclimatic reconstructions obtained with traditional methods. All our data will be made available to other users and will represent a novel reference for climate reconstructions because currently, despite the recognized potential of dendroanatomy, no chronology of anatomical traits covering the last two millennia has yet been developed.