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The Silver Flowe, Galloway, Scotland

D. A. Ratcliffe and D. Walker
Journal of Ecology
Vol. 46, No. 2 (Jul., 1958), pp. 407-445
DOI: 10.2307/2257404
Stable URL: http://www.jstor.org/stable/2257404
Page Count: 46
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The Silver Flowe, Galloway, Scotland
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Abstract

(1) The Silver Flowe consists of a series of blanket bogs differentiated by physiography and at one end of the series showing marked affinities with raised bog. (2) The definitive vegetation type of each individual bog is a Sphagnum-dominated pool and hummock complex. The more southerly bogs also possess features analogous to the laggs and rand of a true raised bog and these have their own distinctive communities. (3) The pool and hummock complex is described in terms of a small-scale succession involving several recognizable stages. (4) To facilitate quantitative description, the pool and hummock complex is divided into four vertical levels (pool, flat, medium hummock and tall hummock) and different micro-communities are recognized within each one. The floristic composition of these units was analysed by the selective placing of a 1 m. quadrat. (5) The pattern of pool and hummock complex is complicated by different developmental trends, often involving erosion. These differences and also the cover of each `level' on each bog were estimated by means of a grid. A subjective comparison of the various bogs is also given. (6) A method was devised to measure quantitatively the relationship between the vertical distribution of plant species and water level. (7) The stratigraphy of two bogs of the series is described and shows (a) that the two patches are more closely akin to blanket bog than to raised bogs; (b) that there has been a relatively recent change-over from a Sphagnum-Molinia community to the present pool and hummock complex. Suggestions are made about the possible causes of the rise in water table which is thought to have initiated this change. (8) The pool and hummock system is not regarded as a `regeneration complex' but the validity of considering the various stages as part of a small-scale succession is discussed. Three possible future developments of this community are envisaged. (a) Persistence of pool and hummock complex, with a very high water table. (b) Development of intermediate bog, with a rather lower water table. (c) Degeneration of pool and hummock complex, with a rapid and considerable lowering of the water table. On certain bogs, (c) is already an established condition, and the possible causes of degeneration are discussed. Human activity is favoured as the probable cause of most recent changes in the vegetation and surface structure of the bogs. (9) The alignment of pools with their long axes at right angles to the slope is discussed. It is considered that an excess of water on a bog results in the development of pool and hummock complex, with an irregular distribution of these features. When the same condition obtains on a sloping bog, the pools and hummocks become arranged in series parallel to the contours.

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