Växtsamhällen på osorterade cirklar i Abisko : Hur förändrad kryogen aktivitet kan påverka sammansättning och artrikedom av kärlväxter

• Main Author: Berglund, Louise
• Format: Bachelor Thesis
• Language: Swedish
• Published: Institutionen för ekologi, miljö och geovetenskap 2013
• Subjects: non-sorted circles; vascular plant communities; alpine areas; cryoturbation; climate change; Natural Sciences; Naturvetenskap; Arctic; Abisko; Climate change
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-74588

Non-sorted circles are patterned ground features created by cryogenic activity in alpine and arctic areas. In these features, cryogenic activity controls vegetation communities by causing repeated disturbance and therefore provides habitat for species that are poor competitors but can tolerate disturbance. A recent study has shown that there is a trend where shrub vegetation overgrows the bare soil found within non-sorted circles. The aim of this study was to assess how the vascular plant communities on non-sorted circles have changed since 1985 and determine to what extent cryogenic activity affect vegetation communities. The study was conducted in Abisko and the point frame method was used to re-investigate how the plant species composition and richness have changed between 1985 and 2012, while a visual frame method was used to investigate how the plant communities change along a gradient of cryogenic activity. The results showed that the vascular plant communities on non-sorted circles in Abisko have changed since 1985 with a decrease in poorly competitive species, and an increase in competitive species. My results suggest that species richness is favoured by cryogenic activity, as the highest species richness was found on intermediately disturbed sites and on the transition zone between bare soil and fully developed vegetation cover. My findings indicate that poorly competitive species will lose habitat and become outcompeted by other species when cryogenic activity decreases, and therefore I conclude that there is a risk of local loss in vascular plant species richness in alpine areas.