Behind the scene of arctic-alpine greening – implementing a multi-parameter approach to disentangle the controls of spatio-temporal variation in dwarf-shrub growth

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The observed, mainly dwarf-shrub induced, greening of arctic-alpine regions is likely to cause impacts at local to global scales. Facing this importance, it is inevitable to get knowledge about the underlying drivers of the current patterns of both primary production and phytomass. Consequently, recent studies focus at the mechanisms behind the increase of phytomass and the expansion of dwarf shrubs. They are, however, often based on remote-sensing studies of entire biomes or regions at comparably coarse scales. Obviously, such studies can neither account for the fine-scaled heterogeneity of especially alpine regions, nor for the actual growth response of dwarf shrubs that is triggered by ecophysiology. As such, approaches that account for the fine-scaled heterogeneity of arctic-alpine regions while studying the growth response of dwarf shrubs are lacking. Thus, the presented research project aims at a spatio-temporally fine-scaled ecological interpretation of the growth dynamics of the woody vegetation, which will be conducted along micro-topographical and altitudinal gradients in the alpine region of central Norway. We will follow a multi-parameter approach to disentangle the driving forces of shrub growth that, for the first time, also includes a systematic recording of the growth dynamics of characteristic dwarf-shrub species at a high temporal resolution based on dendrometers. This offers the opportunity to bridge the gap within the causal chain of cell division and cell enlargement, both of which are ecophysiologically triggered by short-term events, and the annual ring width that integrates over the entire growing season.