In this seminar, I will present and discuss some of the results from my thesis: Subarctic bryophyte ecology: phenotypic variation and responses to simulated environmental change. (Jägerbrand, 2005).
Global Climate Change is currently intensifying and causes redistribution of the Earths biomes and vegetation zones. At high latitudes and altitudes, the Global Climate Change is most pronounced, resulting in rapid and severe climatic changes. For example, the Arctic is currently facing the world's highest rates of climatic change, twice the rate of the rest of the world. The Global Climate Change will induce an expansion of forests in the tundra biome, and the present tundra vegetation will greatly change in composition.
Owing to the decrease of vascular plants at higher latitudes and altitudes, bryophytes and lichens increase in relative dominance and play significant roles in e.g. ecosystem functioning, biodiversity, primary production, cover and nutrient cycling. In arctic and alpine tundra, mosses and lichens are expected to decline as the vegetation changes and the global warming intensifies. This is especially alarming since the tundra contains large proportions of the world!ls bryophyte and lichen diversity.
The presentation will show our results from field experiments simulating environmental change (increased temperature and/or nutrient availability) at a subarctic-alpine site in northern Sweden. The short-term effect of a simulated environmental change (increased temperature and nutrient availability) was a decreased bryophyte growth and abundance. After five years of experimental manipulations there was a species impoverishment of the bryophytes and lichens. During the exceptionally warm study period 1995-1999, plant community dominance changed in all plots, including control plots. Consequently, it seems as though the climatic change is already altering the plant communities in northern Sweden. Since we showed significant increases of shrubs after only five years of natural warming it is possible that the predicted plant community changes may occur more rapidly than previously assumed.