|dc.description.abstract||At the CAFF Flora Group meeting held in Helsinki in March 2001, the need for an Atlas of rare and endemic lichens and bryophytes was discussed. Conservation of the biodiversity in the Arctic flora, including bryophytes and lichens as well as vascular plants, is one of the goals that the CAFF Flora Group is aiming at. It is obviously a prerequisite for dealing with conservation of rare or threatened species in this region, to have access to accumulated information on all the species involved and their distribution within the Arctic.
An Atlas of Rare Endemic Vascular Plants of the Arctic had been published as CAFF Technical Report No. 3 in 1999. The conclusion was made at the meeting that similar information should be accumulated for lichens and bryophytes as well. It was clear, however, that because of scant information on the distribution of lichens and bryophytes in many regions of the Arctic, we had to approach this task in a different way from what was done in the case of vascular plants. Before picking out and identifying the rare taxa, it was a prerequisite first to compile a total list of all species in the Arctic, and then filter out a preliminary list of the rare and endemic species, that could then serve as a basis for further selection of the species to be included in the Atlas.
It became the responsibility of the first author to initiate the work, compile the first main bulk of information, construct a database and maintain it to keep the data. The second author is responsible for providing
information on the lichenicolous fungi, as well as new data from the Russian Arctic. The third author has provided access to his unpublished database on Greenland lichens. The aim of this paper is to provide both a total checklist of lichens and lichenicolous fungi in the Arctic as well as a preliminary list of rare and endemic lichens (Tables 2 and 3).
The work that had already been initiated towards a Panarctic Flora by the PAF working group was a great help in preparations for producing the initial panarctic lichen checklist presented here. Panarctic checklist of vascular plants had already been made, although not published, providing solutions to some important problems that could be used for the panarctic lichen checklist. This applied to natural delimitation of the Arctic suitable for floristic work, as well as the regional division, both of which were adopted with little changes. The panarctic lichen checklist was first opened on http:// www.arcticportal.org on Dec. 2006. Since then many additions have been made to the list, and a number of dubious species have been dropped off as a result of continuing progress in taxonomic work that has shown them to be synonyms of other known species. A rough estimate of the frequency of the individual species has been added to the checklist, both within the Arctic and outside the Arctic, allowing us to filter out a preliminary list of rare and endemic species in the Arctic. This list should serve as a candidate list that needs to be further refined for inclusion in the Atlas of rare and endemic lichens in the Arctic.||en_US