Spatio-temporal analysis of climate-tree ring relationships

This paper is concerned with the value of the ecological information provided by response functions. Two questions are considered. The first deals with the spatial reproducibility of response functions depending on the tree population and the location of the meteorological station that yielded the climatic data. The second concerns the temporal stability of the response function. The climate-ring-width relationships are calculated for six Populations of Pinus silvestris (L.). Twelve meteorological stations are involved in this calculation, over the period 1890-1980, divided in five sequences of 50 years. Analogies and differences between response functions are investigated using multi-dimensional analysis (principal component analysis and cluster analysis). Spatial analysis reveals that the climate ring-width relationship mainly depends on the population habitat. The temporal analysis shows that instability is linked with the evolution of the habitat, more especially with the expansion of the forest cover.