Spatial classification of moisture-sensitive pine and larch tree-ring chronologies within Khakass-Minusinsk Depression, South Siberia

Key message Growth patterns of Scots pine and Siberian larch under water deficit across an intermontane valley in South Siberia depend not only on landscape physiography but on species-specific climatic sensitivity and phenology. The wide intermountain Khakass-Minusinsk Depression (KhMD) in southern Siberia presents an ideal setting for studying the potential impacts of a warming climate on forest ecosystems. The Centre of Continental Asia has one of the most intense rates of warming in the Northern Hemisphere, and the KhMD has multiple tree species of proven dendroclimatic value growing in drought-stressed environments. Investigation was aimed at spatial patterns of tree growth and its climate response across the KhMD for two main conifer species of moisture-deficient habitats, Scots pine (Pinus sylvestris L.) and Siberian larch (Larix sibirica Ledeb.). Correlation and cluster analysis were applied to a recently developed network of 15 tree-ring chronologies. Hierarchical classifications were based on the inter-chronology correlation matrix and on correlations of chronologies with monthly climate variables. Results underscore the general influence of hot-dry conditions on reducing growth and suggest a spatial grouping of chronologies governed by physiography and modified by species-dependent ecophysiological response to climate. Both applied classifications agree on the designation of geographically oriented clusters. A purely geographic grouping is broken, however, by species-specific climate dependence and phenology in deciduous Larix and evergreen Pinus. A differential ability to utilize melting snowpack in spring is advanced as a possible explanation for chronologies abandoning physiographically defined clusters. Such inter-species heterogeneity can manifest itself in the intensity of the climate change impact on vegetation, and lead to prospects of significant species composition changes in ecosystems.