No divergence in Cassiope tetragona: persistence of growth response along a latitudinal temperature gradient and under multi-year experimental warming.

The dwarf shrub Cassiope tetragona (Arctic bell-heather) is increasingly used for arctic climate reconstructions, the reliability of which depends on the existence of a linear climate-growth relationship. This relationship was examined over a high-arctic to sub-arctic temperature gradient and under multi-year artificial warming at a high-arctic site. Growth chronologies of annual shoot length, as well as total leaf length, number of leaves and average leaf length per year, were constructed for three sites. Cassiope tetragona was sampled near its cold tolerance limit at Ny-Ålesund, Svalbard, at its assumed climatic optimum in Endalen, Svalbard, and near its European southern limit at Abisko, Sweden. Together these sites represent the entire temperature gradient of this species. Leaf life span was also determined. Each growing season from 2004 to 2010, 17 open top chambers (OTCs) were placed near Ny-Ålesund, thus increasing the daily mean temperatures by 1·23°C. At the end of the 2010 growing season, shoots were harvested from OTCs and control plots, and growth parameters were measured. All growth parameters, except average leaf length, exhibited a linear positive response (R(2) between 0·63 and 0·91) to mean July temperature over the temperature gradient. Average leaf life span was 1·4 years shorter in sub-arctic Sweden compared with arctic Svalbard. All growth parameters increased in response to the experimental warming; the leaf life span was, however, not significantly affected by OTC warming. The linear July temperature-growth relationships, as well as the 7 year effect of experimental warming, confirm that the growth parameters annual shoot length, total leaf length and number of leaves per year can reliably be used for monitoring and reconstructing temperature changes. Furthermore, reconstructing July temperature from these parameters is not hampered by divergence

Paleoeconomy more than demography determined prehistoric human impact in Arctic Norway

Population size has increasingly been taken as the driver of past human environmental impact worldwide, and particularly in the Arctic. However, sedimentary ancient DNA (sedaDNA), pollen and archaeological data show that over the last 12,000 years, paleoeconomy and culture determined human impacts on the terrestrial ecology of Arctic Norway. The large Mortensnes site complex (Ceavccagea ¯dgi, 70◦N) has yielded the most comprehensive multiproxy record in the Arctic to date. The site saw occupation from the Pioneer period (c. 10,000 cal. years BP) with more intensive use from c. 4,200 to 2,000 cal. years BP and after 1,600 cal. years BP. Here, we combine on-site environmental archaeology with a near-site lake record of plant and animal sedaDNA. The rich animal sedaDNA data (42 taxa) and on-site faunal analyses reveal switches in human dietary composition from early-Holocene fish + marine mammals, to mixed marine + reindeer, then finally to marine + reindeer + domesticates (sheep, cattle, pigs), with highest reindeer concentrations in the last millennium. Archaeological evidence suggests these changes are not directly driven by climate or variation in population densities at the site or in the region, but rather are the result of changing socio-economic activities and culture, probably reflecting settlers’ origins. This large settlement only had discernable effects on its hinterland in the last 3,600 years (grazing) and more markedly in the last 1,000 years through reindeer keeping/herding and, possibly domestic stock. Near-site sedaDNA can be linked to and validate the faunal record from archaeological excavations, demonstrating that environmental impacts can be assessed at a landscape scale

Twenty of the most thermophilous vascular plant species in Svalbard and their conservation state

An aim for conservation in Norway is preserving the Svalbard archipelago as one of the least disturbed areas in the Arctic. Information on local distribution, population sizes and ecology is summarized for 20 thermophilous vascular plant species. The need for conservation of northern, marginal populations in Svalbard is reviewed, using World Conservation Union categories and criteria at a regional scale. Thirteen species reach their northernmost distribution in Svalbard, the remaining seven in the western Arctic. Nine species have 1-8 populations in Svalbard and are assigned to Red List categories endangered or critically endangered: Campanula rotundifolia, Euphrasia frigida, Juncus castaneus, Kobresia simpliciuscula, Rubus chamaemorus, Alchemilla glomerulans, Ranunculus wilanderi, Salix lanata and Vaccinium uliginosum, the last four species needing immediate protective measures. Five species are classified as vulnerable: Betula nana, Carex marina ssp. pseudolagopina, Luzula wahlenbergii, Ranunculus arcticus and Ranunculus pallasii. Six species are considered at lower risk: Calamagrostis stricta, Empetrum nigrum ssp. hermaphroditum, Hippuris vulgaris (only occurring on Bjørnøya), Juncus triglumis, Ranunculus lapponicus and Rhodiola rosea. The warmer Inner Arctic Fjord Zone of Spitsbergen supports most of the 20 target species and is of particular importance for conservation. Endangered or vulnerable species were found in a variety of edaphic conditions; thus, several kinds of habitats need protection

Dispersal and microsite limitation of a rare alpine plant

Knowledge on the limitation of plant species’ distributions is important for preserving alpine biodiversity, particularly when the loss of alpine habitats because of global warming or land use changes is faster than colonization of new habitats. We investigated the potential of the rare alpine plant Campanula thyrsoides L. to colonize grassland sites of different suitability on a small mountain plateau in the Swiss Alps. A total of 15 experimental sites were selected according to their differences in habitat suitability for adult C. thyrsoides, which was measured by the Beals index. At each site we applied a disturbance treatment, added seeds at different densi- ties and monitored the survival of seedlings over two consecutive years. The number of surviving seedlings was not positively related to habitat suitability for adult C. thyrsoides. Furthermore, C. thyrsoides appears to be strongly dispersal limited at the regional scale because seed addition to unoccupied habitats resulted in successful germination and survival of seedlings. Since an increase of seed density in already occupied sites did not affect the number of seedlings, we suggest that C. thyrsoides is microsite limited at the local scale. Microsite limitation is supported by the result that seedling survival of the species was enhanced in vegetation gaps created by disturbance. We conclude E. S. Frei (&) J. F. Scheepens, J. Sto ̈cklin Section of Plant Ecology, Institute of Botany, University of Basel, Scho ̈nbeinstrasse 6, 4056 Basel, Switzerland e-mail: [email protected] that C. thyrsoides may become endangered in the future if environmental changes cause local extinction of populations. An appropriate management, such as a disturbance regime for enhancing recruitment in existing populations, may ensure the long-term sur- vival of this rare alpine plant species

The Braun-Blanquet project: evaluating and characterizing European vegetation alliances

European tradition on vegetation classification provides an extraordinary legacy for understanding biodiversity. However, this classification lacks explicit data on vegetation attributes, especially if we extend national or regional concepts to a continental perspective. An additional effort for evaluating and characterizing European vegetation types is therefore needed, and the data contained in vegeta­ tion databases are probably the main tool for these purposes. The Braun­Blanquet project is an initiative of the European Vegetation Survey for characterizing veg­ etation alliances across Europe. By analyzing more than 500,000 vegetation plots from 22 European countries, we developed a framework consisting of: (1) evaluat­ ing the consistency and robustness of alliances using the information provided by vegetation plot databases, (2) calibrating assignment rules for classifying, at least partially, the plots not assigned to alliances and (3) characterizing vegeta­ tion types by providing lists of diagnostic species and major distributional pat­ terns. The Braun­Blanquet project represents the first attempt for extrapolating European vegetation information into a comprehensive definition of vegetation types. Furthermore, the outputs of the project are expected to improve biodiver­sity assessment and the conservation management of natural habitats. As a study case, we illustrate how our framework can be used to characterize different forest types across Europe

The Braun-Blanquet project: evaluating and characterizing European vegetation alliances

European tradition on vegetation classification provides an extraordinary legacy for understanding biodiversity. However, this classification lacks explicit data on vegetation attributes, especially if we extend national or regional concepts to a continental perspective. An additional effort for evaluating and characterizing European vegetation types is therefore needed, and the data contained in vegeta­ tion databases are probably the main tool for these purposes. The Braun­Blanquet project is an initiative of the European Vegetation Survey for characterizing veg­ etation alliances across Europe. By analyzing more than 500,000 vegetation plots from 22 European countries, we developed a framework consisting of: (1) evaluat­ ing the consistency and robustness of alliances using the information provided by vegetation plot databases, (2) calibrating assignment rules for classifying, at least partially, the plots not assigned to alliances and (3) characterizing vegeta­ tion types by providing lists of diagnostic species and major distributional pat­ terns. The Braun­Blanquet project represents the first attempt for extrapolating European vegetation information into a comprehensive definition of vegetation types. Furthermore, the outputs of the project are expected to improve biodiver­sity assessment and the conservation management of natural habitats. As a study case, we illustrate how our framework can be used to characterize different forest types across Europe