| dc.description.abstract | Climate warming is inducing compositional shifts in alpine species communities across Europe. However, there are variations in the magnitude and direction of these shifts related to variations in the abiotic environment. Increased number of micro-climates in a habitat, where species can “escape” the changes in the general environmental, is theorized to increase the temporal stability of species compositions. To study such relationships between the abiotic and biotic environment, researchers has collected different aspects of the abiotic environment under the term geodiversity. Novel techniques for quantifying geodiversity are being presented and include aspects such as geology, geomorphology, hydrology, and topographical heterogeneity. All these have been found to influence species composition, and geomorphology has been related with temporal stability in species communities. It is expected that the number of geodiversity features in a habitat lowers the magnitude of compositional shifts and increases biodiversity. In this thesis I study the temporal shifts in vascular plant species compositions of in the alpine research area of Hirkjølen, Norway. I use Pythagorean distance to measure the size of compositional shifts from 1932 to 2020 in 40 permanent plots in a Non-metric Multidimensional Scaling ordination. I found that georichness, especially geomorphology, lowers the magnitude of compositional shifts. Also, plots at higher elevations experience smaller shifts than those at lower elevation. This could be due to increased anthropogenic disturbance, such as grazing or cabin construction, at lower elevations. There was also a difference in direction of shifts along the elevational gradient. At lower elevations species communities are becoming more similar to low-georichness habitats with higher presence of Picea abies and berry heather forest-species. At higher elevations there were shifts toward both alpine and lowland species compositions. This was likely due to relaxed temperature constraints and competition release from climate warming, but also grazing is likely to have induced these shifts. It will be of interest if future studies look at how georichness influence changes in species compositions caused by such anthropogenic influence. There is also a need to look into on how individual geodiversity components influence temporal development as I found them to have varying degree of influence. This has been the first study to look at plot-scale geodiversity and relate it to temporal development of species communities. Currently, there is a great need to study the relationship between geodiversity and biodiversity, especially in the face of climate warming, and a lack of studies on geodiversity. | |
