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Makoto, K./ J. Klaminder 2012: The influence of non-sorted circles on species diversity of vascular plants, bryophytes and lichens in sub-arctic tundra. - Polar Biology 35(11): 1659-1667. [RLL List # 231 / Rec.# 34611]
Keywords: Climate change/ Cryoturbation/ Frost boil/ Periglacial process/ Plant species diversity/ bryophyte/ climate change/ cryoturbation/ frost/ lichen/ lichenometry/ periglacial environment/ plant community/ shrub/ species diversity/ subarctic region/ succession/ tundra/ Arctic/ Bryophyta/ bryophytes/ Tracheophyta
Abstract: Non-sorted circles (NSCs), also known as frost boils, are common soil frost features that create a small-scale mosaic of vegetation zones in periglacial landscapes. The causes of variation in plant diversity within NSCs are poorly understood. This lack of understanding hampers our ability to predict how arctic plant communities respond to changing soil frost conditions. We hypothesised that plant communities of different ages develop at a micro-site scale within NSCs as soil frost periodically exposes uncolonised soil or fatally offsets plant succession. To test this hypothesis, we investigated the species diversity of plant communities (vascular plants, bryophytes and lichens) from the sparsely vegetated centre of the circles to the densely vegetated outer domain in conjunction with estimates of the age of the plant communities (inferred using lichenometry). Our results suggest that the variation in species diversity and density can largely be explained by the occurrence of progressively older plant communities from the centre towards the vegetated rim. Here, the high species diversity was observed to occur in communities having the ages approximately around 150 years. Our findings suggest that soil frost disturbances are important for maintaining successional gradients several centuries long within the arctic landscape at a small spatial scale (<3 m). The termination of soil frost activity as a result of a warmer future winter climate is therefore most likely to result in a loss of micro-sites having young vegetation communities with high plant diversities and a subsequent establishment of mature shrub-dominated plant communities. © 2012 Springer-Verlag.
URL: http://dx.doi.org/10.1007/s00300-012-1206-3
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