The ranges of many species are shifting to higher latitudes and altitudes in response to the climatic warming of recent decades. However, some plant species are moving uphill or northward while others are not. If we want to protect biodiversity, we need to understand why these different responses happen. How can species react to the current rapid and accelerating climatic changes when they live in fragmented natural habitats and landscapes?
The KlimaVeg project assembled teams of scientists from Poland and Norway who are experts in climate-linked vegetation changein forests and alpine habitats. In KlimaVeg, we resampled alpine phytosociological data sets and permanent forest plots in Norway and Poland to investigate shifts in species ranges and changes in community species composition. Our data was related to changes in climate and other driving factors, such as changes in land-use (e.g. grazing intensity, tourism).
We found that in the lowlands of the temperate and boreal climate zones, plant biodiversity is changing but the change is usually less pronounced than in mountains. Climate drives changes in the frequency and elevation of high Arctic species, and subsequently in the species composition of high Arctic vegetation. In mountain ecosystems high intensity grazing slows or buffers the affects of climate, while hiking (tourism) showed no relationship to the species elevational shift. The strength of the grazing effect is climate-dependant. In Tatry Mts. climate warming is clearly responsible for changes in snowbeds and alpine tall herb communities at high elevations. The cessation of sheep grazing is the strongest driver of changes in plant species composition since 75-150 years ago in high-elevation granite grasslands of the Tatra Mountains, both on summits and in mountain valleys.
The forest communities are very dynamic. We detected more species in the recent surveys than the previous one for lichens and vascular plants. Bryophyte species richness and species composition seem to be the most stabile between the studied groups of organisms. Climate may play a role here, but so does observer effect and natural disturbances. In Norwegian forests the changes inspecies composition are not related to temperature or precipitation, but instead to changes in light and soil nutrients accessibility. Much of the observed changes are likely to be due to the combination of cessation of traditional forest management and increased storm activity. In Polish Białowieża Forest significant ecological indicator value increases for light, temperature, soil reaction and nitrogen. However, these changes are related rather to natural disturbances, such as spruce bark beetle outbreaks in coniferous forests or fungal diseases causing large-scale European ash dieback in bog forests, than to climatic factors. On the other hand mean weighted values of the ecological indicators of vascular plants, bryophytes and lichens of all studied communities change in the same direction, even if some of the changes are not very strong. Such a compatible reaction strongly suggests existing of some strong factor influencing all types of disturbed and not-disturbed forest communities. Additionally we revealed significant acceleration of flowering time for most observed forest understorey plant species, which was strongly correlated with temperature increase of late winter and early spring months (February-April). These are a clear signal of the climate related changes in functioning of plants on both: species/individual level and community level.
The climate change signal is best trackable in the mountains at the highest elevations, where historical land use did not disturb the natural character of vegetation. At lower elevations and at lowland, the effect of historical land use predominates as local vegetation is slowly regenerating to its natural state. This regeneration process swamps large part of the effect of climate change on the community level, which becomes difficult to trace.
The project strengthened an existing Norway-Poland collaborative links between institutional leading partners, which prior to the project existed just between single researchers. It also created several new working relationships between scientists, which will endure beyond the lifetime of the project. Joint field missions have enabled increase of knowledge and skills, and allowed exchange of ideas and information. The project network, which at the initial stage of writing of the project proposal composed of only two research institutions, now incorporates eight scientific institutions from four countries.