Pattern in the simple moss-turf communities of the sub-Antarctic and maritime Antarctic

(1) Grids of 1500 (300 × 5) 2 × 2 cm quadrats have been recorded on three moss-turf sites: South Georgia in the Sub-Antarctic (three dominant species), and in the maritime Antarctic on Signy Island (two dominant species) and on Galindez Island (a virtual monoculture of Polytrichum alpestre). (2) Two methods of pattern analysis, the stepped blocked quadrats variance method and the two-term local quadrat variance method, have been used on all data. It is stressed that there is as yet no satisfactory technique for exploring pattern in belt transects. (3) It is suggested that the pattern in the simplest of these communities, Galindez Island, is due to the alternation of mossy areas, or hummocks, and bare ground. (4) At Signy Island there is a well developed pattern, with two scales of heterogeneity at about 20 cm and at 1.2-2.0 m. The latter is considered to be due to the history of vegetation development, which is determined by the distribution of rocks now beneath the surface of the moss carpet. (5) The South Georgia community has two scales of pattern similar to those on Signy Island, but the factors determining them are unknown. In this three-species community both positive and negative associations are indicated. (6) On all sites, virtually all analyses indicated a small scale of pattern at about 20 cm. It is considered that this scale is important when sampling both the vegetation and the animal communities living within the moss-turf communities.


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Authors: Usher, M.B.

1 January, 1983
The Journal of Ecology / 71
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