Natural History in the Highlands and Islands by F. Fraser Darling

Author:F. Fraser Darling [F. Fraser Darling D.Sc. F.R.S.E.]
Language: eng
Format: epub
ISBN: 9780007406098
Publisher: HarperCollins Publishers

CHAPTER 9

THE SHORE, THE SEA LOCH AND THE SHALLOW SEAS

THE SHORE LINE AND THE INTERTIDAL ZONE

NOT ALL Highland coasts are wild and forbidding. There is an extreme contrast, however, between the western points such as Ardnamurchan, Greenstone, Rhu’ Mor Coigach, Stoer, Cape Wrath, the Butt of Lewis and Barra Head, and the sheltered sea inlets of Loch Broom, Loch Carron, Loch Sunart and Loch Fyne. The one means ocean, the others little more than salt water without storm. The winds met on the outer coasts render the habitat comparable in many ways with the summits of the hills. The outer coasts are washed with driven spray and rain so that what little grass they grow is sweet and clean, and much liked by the sheep and cattle which graze there. The main difference between the summits and the outer coasts is in winter temperature and the effects of snow-lie. Apart from that the rigour is similar. Many plants of the shore, the cliff face and the top of the cliff have to endure drought conditions caused by lack of humus acting as a sponge for water, from extreme paucity of soil for their roots and from the physiological drought caused by salt water. It is common, therefore, to find plants with tightly rolled leaves such as viviparous sheep’s fescue which we found on the summits; some plants have deeply ribbed leaves, very stiff, such as marram grass (Ammophila arenaria); some have polished glossy leaves, like scurvy grass (Cocklearia officinalis); there are little linear crowded leaves like those of sea pink, and fleshy ones like roseroot and stonecrop (Sedum anglicum) which absorb moisture and store it. All these plants are more or less drought resistant, achieving their end by one means or another. Then there are others such as orache (Atriplex patula) and bladder campion (Silene maritimus) which are common on shore and cliff and yet do not show any particular adaptation of leaf to a droughty or salty habitat. Orache, indeed, is a common weed of gardens and arable land far from the sea. The curled dock (Rumex crispus) has a leaf form which enables it to resist some measure of drought and it is in fact often found on shingle beaches below the line of the highest spring tides, and on cliff faces. This plant occurs as far afield as North Rona, nearly fifty miles from other land, but only in certain cliff faces. One of the reasons why it is found in such situations on this and many other islands off Highland coasts is that, being a weed of corn land, it gets picked up by the gulls at seeding time on the crofts, when the birds are already roosting at their gulleries on the cliffs. The gulls cast up the indigestible husks of the oats as a bolus, and the dock seeds, untouched in their hard shiny coat, germinate easily.

The orache, bladder campion and curled dock all show in their foliage from time to time a common effect of drought in the way their leaves turn red.

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