Summit peats ('peat cakes') on the fells of Finnish Lapland:: continental fragments of blanket mires?

Peat deposits of area up to 50 m(2) and thickness of 10-50 cm on fell summits at 370-622 m a.s.l. in northern Finland have been mapped, analysed and dared. These summit 'peat cakes' are most frequent in northwestern Inari Lapland, in a relatively continental climate and close to the Arctic Ocean. It seems that the most important local factor for their development are irregularities in microtopography, which collect drift snow and shelter plants from destructive winds. Most sites are dominated by Empetrum nigrum ssp. hermaphroditum. Accumulation of peat started after the Atlantic period c. 4000 C-14 years BP, when the climate became more humid. The mean annual growth of seven investigated deposits ranged from 0.11 to 0.44 mm yr(-1). Plant macro-remains at Kuovdaoaivi provide evidence of gradual vegetation development from an Empetrum-dominated community to a more diverse one: macro-remain concentration and the number of species rise gradually to the top of the deposit. At present, summit peats are being eroded by deflation, enhanced by needle ice and reindeer overgrazing. It seems that these peat deposits represent embryonic blanket mires at the continental limit of high-latitude blanket mire distribution.