Modelling index of thermophily by means of a multi-source database on Broggerhalvoya Peninsula (Svalbard)

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Abstract
In the Arctic, plant species are at their physiological tolerance limit. Anthropogenic induced climate changes may thus have fundamental consequences on arctic plant life in the near future. Summer temperatures are by far the most important factor determining the general distribution of plants over large areas. According to different meteorological stations, mean July temperature on Svalbard is in the range 2-6°C. Nevertheless, there are large local gradients in the Svalbard landscape. A method has been developed that uses the plants as climate indicators. This index of thermophily uses the whole species diversity, with increasing values based on increasing concentrations of plants requiring higher temperatures within the temperature range cited from Svalbard above. This index can be useful for predicting scenarios about development of arctic vegetation due to the global change effects if we can determine the environmental factors controlling its spatial variation. The function of these environmental variables is analysed according to a regional and a local scale. At each scale, modelling index of thermophily values distribution is done within a GIS, using different variables as predictors. At the regional scale, covering the Brøggerhalvøya peninsula, spatial distribution of index values is correlated with latitude and longitude and shows a continentality effect. At the local scale, other predictors like topography (gradient, aspect, altitude) and satellite data (NDVI, temperature from TM6, classification results) are tested. Finally, a combination of the models for the different scales enables us to map the distribution of index of thermophily.