Decreased cryogenic disturbance: one of the potential mechanisms behind the shrubification of non-sorted circles in subarctic Sweden
(English)Manuscript (preprint) (Other academic)
During the last few decades, the arctic has experienced large-scale vegetation changes often evident as widespread greening (increased NDVI) in satellite images. Understanding the mechanisms behind this greening is crucial for our ability to predict future vegetation changes. The objective of this study was to test the hypothesis that decreased cryogenic disturbances have contributed to the greening of patterned ground fields (non-sorted circles) in the study site (Abisko, Northern Sweden) during the last few decades. The hypothesis was tested by surveying the composition of plant communities across a gradient in cryogenic disturbance and by reinvestigating plant communities previously surveyed in the 1980s to scrutinise how these communities changed in response to reduced cryogenic disturbance. Whereas the historical changes in species occurrence associated with decreased cryogenic disturbances were fairly consistent with the changes along the contemporary gradient of cryogenic disturbances, the species abundance revealed important transient changes highly dependent on the initial plant community composition. Our results imply that the decreased environmental stress from differential heave during winter in recent decades is one of the mechanisms that has contributed to the greening of the patterned ground in the study area, although more than a few decades are likely required before this decreased stress contributes in a substantial way to the on-going shrubification.
Patterned ground, Plant abundance, Non-sorted circles, Freeze/thaw-index, Cryogenic disturbance, Differential heave
Other Earth and Related Environmental Sciences
Research subject Physical Geography
IdentifiersURN: urn:nbn:se:umu:diva-112507OAI: oai:DiVA.org:umu-112507DiVA: diva2:882510