Juha M. Alatalo

TL;DR: Principal response curve, cover and richness results suggested that bryophytes in alpine heath are more susceptible to warming than in meadow, supporting the suggestion that brysophytes may be less resistant in drier environments than in wetter habitats.

TL;DR: In this article, a new parsimonious approach was proposed to simulate direct and indirect effects of global warming on plant communities in an alpine vegetation community and gained insights into the role of biotic interactions as determinants of plant species response to climate change at local scale.

TL;DR: It is shown that, besides topography (slope and aspect), climate itself can produce a braking effect on the upslope advance of subalpine forests and that tree limit is influenced by non-linear and non-monotonic contributions of the climate variables which act upon treeline upsl slope advance with varying relative strengths.

TL;DR: The relative contribution of bryophytes to plant diversity, primary productivity, and ecosystem functioning increases towards colder climates as mentioned in this paper, and they respond to environmental changes at the speci c...

Abstract: This thesis concerns the effects of the anticipated climate change on a circumpolar cushion plant Silene acaulis, and on two common types of subarctic plant communities. The predicted changes in c limate over the next 50 years are expected to be particularly large in arctic and subarctic regions. Earlier studies has mainly aimed at responses of single species, particularly vascular plants. In order to better understand the possible responses of subarctic-alpine plant communities. Manipulative field experiments was applied on different scales: detailed study of reproductive and vegetative responses of a common circumpolar plant species (Silene acaulis), and effects on biodiversity, structure, biomass, and reproduction, of two contrasting plant communities (rich meadow and poor heath, respectively, including non-vascular plant species). The results show that S. acaulis may respond positively in reproductive terms to an increase of its temperature regime, and that both temperature and nutrient treatments had positive effects on vegetative characters. The result of main importance is that there can be considerable variation of responses, in time, and space, of individual plants species to environmental perturbations at various scales in a seemingly homogenous vegetation community. Thus, individual plants respond differently depending on their physical environment and genotype. This is probably caused by differentiated competition occurring at spatial scale (depending on neighbour plants), whereas the variation in time is probably a chaotic effect due to unpredictable weather conditions among years. The studies at the plant community level shows that responses to environmental manipulations may vary both among functional plant groups, as well as within functional groups among plant communities. Consequently competition success may shift among functional plant groups depending on the vegetative structure of the plant community. Further, bryophytes tended to respond in negative manner whereas lichens responded in neutral or positive manner, the responses depending on the vegetative structure of the vascular plant community. This may cause considerable changes in biodiversity and vegetation structure of subarctic-alpine plant communities in the