This paper deals with the habitat of Sphagnum girgensohnii Russ. which occurs usually in subalpine forests in Japan. The habitat of S. girgensohnii was investigated at 32 sites of different topographical conditions in a subalpine coniferous forest of Mts. Yatsugatake, central Japan. Sphagnum girgensohnii forms discrete colonies at the forest floor, and occurs much more on the lower part of the slope. In this area, there is a considerable differentiation in their microrelief caused by lave flows or boulders. Sphagnum girgensohnii is restricted to the hollows. The forest floor is generally covered with humus. Sphagnum girgensohnii grows on thicker layers of humus than other bryophyte species. The result obtained from this study suggests that soil surface moisture is a limiting factor in the formation and maintenance of colonies of S. girgensohnii.

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A plant community on a moraine at the deglaciated front of East Brogger glacier in Ny-Alesund, Spitsbergen, Svalbard archipelago and composed primarily of bryophytes was studied to clarify the vegetation dynamics in polar region. We studied the vegetation on the moraine using the quadrat method along a line transect from the edge of the glacier to a point 850m downstream, and recorded cover (%) of species observed in each quadrat. No significant difference can be found along the line transect in hydrogen-ion concentration (pH) and electric conductivity (EC) in soils. The number of species tended to increase with increasing distance from glacier edge, but there was no visible change at the central part of moraine. Gradients of equitability (Ec) and dominance concentration (Simpson Index: C) were shown along the line transect, so it was considered that diversity of moraine community was approximately increasing in the downstream direction of the moraine. However, it was also understood that importance value concentrated to dominant species at the central part of moraine.

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