Types of grassland
Not all grassland is the same. Some grasslands, such as those of the Solway merse, Hebridean machair or Caithness cliffs are natural. These have evolved to withstand immersion by floods and tides, or exposure to winds and salt-laden storms.
Saltmarsh, immersed by the tides, comprises a more or less continuous turf of grasses and wildflowers. Grasses such as sea poa, in the most frequently inundated lower marsh, give way to others such as red fescue in the upper parts of the marsh. The upper reaches, immersed by only the highest Spring Tides, are used to graze cattle and sheep during summer. They may be tinged pink by drifts of thrift or, in late summer, purple by the Michaelmas daisy-like flowers of sea aster. Salt marshes are key winter resting and feeding places for migratory wildfowl; the Solway merse supports the entire Spitzbergen population of barnacle geese throughout the winter.
Machair is a coastal grassland found in the north-west highlands and islands of Scotland. It occurs where rapidly shifting dunes of shell-sand are colonised first by marram grass, then by other species of plant like red fescue and sand sedge – the latter bringing order to chaos as its shoots rise from dead-straight rhizomes to make dotted lines across the sand.
Machair is renowned for its vivid displays of colourful wild flowers. Dune slacks, pale with silverweed, are mottled gold by its flowers and by those of marsh marigold and lesser spearwort. They are tinged with the delicate pink of lady’s smock, the rose pink of ragged robin and later in the year, the deep red of marsh cinquefoil. The dry grassland starts with the whites of daisies and progresses to the yellows of buttercups, birdsfoot-trefoil and lady’s bedstraw.
Machair is often used for rough grazing, a practice which helps to maintain it. The machair around the Uists and Benbecula provides one of the most important breeding grounds for wading birds in the northern hemisphere.
‘…the most numerous breeding wader of the machair is the lapwing and they were beating and wailing over the ploughs and men, … diving close to my head and flinging themselves away, making loud percussive thrumming noises with their wings.’
Nowhere else in the British Isles do oystercatchers, ringed plovers, lapwing, dunlin, snipe and redshank breed in close proximity in such high densities.
Cliff-top grasslands, carpeted in close-cropped red fescue, are favoured by choughs, a species of bird once widespread in Scotland but now virtually restricted to Islay and Colonsay. The specialised lifestyle of choughs restricts them to short grasslands where they feed upon small creatures in the soil and dung.
Much to the detriment of maintaining or expanding the chough population, some of the modern pesticides which are given to cattle to kill parasites in their guts pass through the animal and are still poisonous to insect larvae in the dung. To avoid depriving grassland birds of food, cattle in a herd should be dosed at different times, or by a single dose rather than by continuous release bolus.
The chief factor determining the character of grasslands is the soil. The soil reflects the material from which it has formed. So important is the influence of the soil in determining which plants can grow that it is this characteristic that is used to describe the grassland. When grassland is called ‘neutral’, ‘base-rich’ or ‘acidic’, these terms are really describing the soil upon which the grassland has formed.
As well as the type of soil, its water content is a limiting factor. Farmers prefer grasslands on freely draining soils, but must often make do with marginal land that is periodically flooded or even permanently water-logged.
Neutral grasslands grow on soil which is well drained, well balanced in nutrients and fertile, hence it is hospitable to a wide range of plants and creatures which, in turn, enhance the quality of the soil by their actions. Earthworms eat dead leaves, making them easier for soil bacteria to break down; they also mix the soil, bringing in air and improving drainage in the process.
Charles Darwin calculated that, In one year, worm casts deposited on pasture may amount to 16 tonne an acre, equivalent to a layer of soil 5mm deep being deposited each year and enough over time – as he observed – to bury stones in old pasture.
Hedgehogs and moles, foraging underground and rarely seen, feed on the earthworms, insects, slugs and snails and help to keep their populations in balance.
Because the quality of the soil and the drainage are so good, most of the neutral grasslands in Scotland have been converted to arable crops, or reseeded and dosed with mineral fertiliser to create grass leys. In some areas, these leys are favoured by brown hares and by wildfowl, particularly geese; however, the practice of frequent cutting for silage poses a risk to young birds and animals and makes leys unsuitable as breeding grounds for wild animals.
The few remaining traditional neutral grassland sips can often be identified by their profusion of grasses and wildflowers such as crested dog’s-tail and hardheads, the latter named after their tight blackish buds which later blossom into feathery purple flower heads. Closer to the ground in these areas grow bright yellow birdsfoot-trefoil and dandelion-like cat’s ear which, instead of a smooth flower stalk, has one with cat’s ear-like scales. The flowers of lady’s bedstraw are tiny and bespeckle the sward with dusty yellow. Traditionally this grassland was grazed over the winter, then lightly manured and ‘shut’ to allow the grasses to grow. The grass was cut for hay in late July or early August. It is still cut for hay on crofting lands in Lochaber and survives as pasture in small patches elsewhere in Scotland.
‘Moles do not dig constantly or specifically in search of food. Instead, the tunnel system, which is the permanent habitation of the mole, acts as a food trap, constantly collecting invertebrate prey such as earthworms and insect larvae. As they move through the soil, invertebrates fall into the mole run and often do not escape before being detected by the patrolling resident.’
Hardheads, also known as knapweed or horse knot, has been used to foretell the future of love. A girl would put the head with tight-closed florets inside her blouse. If an hour later the florets had blossomed, she would be lucky in love.
In Perthshire valleys, remnants of a rare flower-rich type of meadow can occasionally still be found. These are characterised by sweet vernal grass, which gives new-mown hay its heady aroma, and by abundant wood cranesbill with its open magenta flowers. Lower growing herbs include lady’s mantle, sorrel and ribwort plantain with their nodding white stamens which, like grasses, release their pollen into the wind. The small herb eyebright also grows here – so named because its white flowers mottled with purple and yellow are reminiscent of a bruised eye and were once prescribed by herbalists as a treatment for eye disorders – as does the rare baldmoney, which can resemble a green hedgehog when left standing proud in pasture.
On road verges and railway embankments, where neutral grassland is ungrazed and rarely cut, oat grass predominates with tall herbs such as cow parsley and meadow cranesbill.
Lady’s mantle was prescribed by herbalists to stem bleeding. It was also valued by alchemists in their attempts to turn base-metal to gold, hence its Latin name – Alchemilla.
Field workers to slake their thirst used sorrel – also known as sourock. It was also used as a garnish for fish and meat and to take rust marks out of linen.
Highlanders used baldmoney or spignel to give food a spicy flavour and also chewed the roots as a stimulant and to relieve flatulence.
Flora Britannica says of cow parsley, also known as Queen Anne’s lace, that ‘For nearly all of May, almost every country road is edged with its froth of white blooms.’
‘Base-rich’ soil is formed from rocks like limestone, serpentine and old red sandstone. Like them it is rich in calcium and other ‘bases’ and supports plants which are ‘lime-loving’. This type of soil is uncommon in Scotland, and the base-rich grasslands it supports are of limited extent.
The most common type of base-rich grassland, usually found on south-facing slopes, is characterised by bent and fescue grasses and wild thyme. Thyme is easily spotted by its tiny purple flowers and the smell of its crushed leaves underfoot. Also visible in base-rich grassland are quaking grass with its nodding heads, fairy flax, rockrose with its big bright yellow flowers, cat’s-foot with its white silky-haired leaves and the upright spikes of field gentian and orchids – some conspicuous such as common spotted orchid while others, such as frog orchid, are seen only at close range.
In the north and west of Scotland, another type of base-rich grassy heath can be found. This is distinguished by mountain avens which has tiny oak-like leaves and large white eight-petalled flowers in June or July, and by carnation grass (actually a sedge, not a grass) named because of its blue-green leaves. These two species are often found growing together with sea plantain, which also features in high-level grasslands and on salt marshes.
Butterflies fluttering on their seemingly carefree way appear to have little to do with grassland. They alight casually on wildflowers and refuel, using their long tubular tongue as a drinking-straw to suck up nectar. But when looking for a suitable plant on which to lay their eggs, they are very fussy. Their eggs hatch to release caterpillars which, although voracious vegetarians, will eat only specific plants. Northern brown argus caterpillars, for instance, feed upon rockrose, dark-green fritillaries upon common violet and common blues upon birdsfoot-trefoil.
Grazing animals often prefer the plants found on base-rich grasslands to other types of vegetation which may be growing nearby. In some areas this has caused severe problems with overgrazing. On Skye, base-rich grasslands have been so intensively grazed by sheep as to lead to erosion and scree formation, even at low altitudes.
Wild thyme contains thymol, a reasonably powerful antiseptic; flowering sprigs were used to scent linen. Thyme-tea was popular as an everyday drink and, in the Western Isles, thyme was put under the pillow or drunk as an infusion to prevent nightmares or otherwise give a restful sleep.
Fairy flax, also known as purging flax, was used as a laxative.
Acidic rock types and the soils produced from these and from glacial drift are extensive throughout Scotland. Only a limited range of lime-avoiding plants can thrive on these acidic soils.
Acidic grasslands may be characterised by heath bedstraw with bent and fescue grasses, often mixed with tormentil, common violet and mountain pansy. Such grassland is common and is widely used as pasture for sheep so that, despite the relatively poor nutrition they provide, by their sheer extent they make an imporant contribution to Scottish agriculture.
The beautiful, but diminutive, mountain pansy was used by James Grieve, a gardener and plant breeder of Edinburgh, as one of the forebears of the garden pansy.
Tormentil was used to treat calves and children with stomach-ache. In Shetland it is known as eart-barth (earth bark) and was used, in the absence of tannin from oak bark, as a source of red dye for fishing nets.
Blaeberry and heather may remain in grassland originating from moor, and heath bedstraw grassland readily reverts to moorland if grazing pressure is removed. Conversely, a consequence of intensive grazing is that plants avoided by sheep, such as mat grass, tufted hair-grass and bracken (which stores its resources in underground rhizomes) are able to spread.
In acidic grasslands, small heath and meadow-brown butterflies lay their eggs upon fine-leaved fescues. Short-tailed field voles, feeding on grass stems and roots, in turn fall prey to short-eared owls. Rabbits are common, particularly where the soil is easily excavated, and they too make easy meals for buzzards, foxes and stoats.
On thin-soiled rocky knolls, a mixture of bent and fescue grassland is found with sheep’s sorrel and a variety of other small plants. Some of these, like maiden pink and shepherd’s cress, are rare in Scotland. Because the soil layer on these rocky outcrops is thin, it dries out quickly and most of the plants found here are annuals which survive the driest months as seed. A few, such as biting stonecrop, have succulent leaves that store water for the dry season. On moist peaty soils, another form of heath bedstraw grassland can be found, characterised by an abundance of highly unpalatable mat grass, which is easily identified in winter by the pale yellow, almost white clumps. This type of grassland provides poor grazing.
Periodically flooded grasslands
In the Western Isles, well-drained grasslands are scarce. Grasslands that are flooded from time to time are indicated by the yellow blobs of marsh marigold and the pinks and reds of ragged robin and marsh cinquefoil. These areas are often managed by farmers or crofters as meadows to produce ‘bog hay’.
In low-lying coastal areas, plants such as yellow flags, tufted hair-grass and soft rush thrive on agricultural land that is wet, poorly managed or abandoned. Cattle tend to avoid these plants, so they are able to spread and form clumps. These clumps provide vital cover for the nests of wild birds like snipe and corncrake. Until recently, corncrakes seemed destined for extinction in Scotland – they were confined to a few shrinking populations, mainly based in the Hebrides. Now, thanks to the introduction of wildlife-friendly mowing techniques, delayed cutting and leaving patches of tall vegetation for ‘early cover’, corncrake numbers have begun to rise again.
Where water comes to the surface of the ground in ‘flushes’, water-loving plants like butterwort, sedges and mosses can be found, or, in late summer, grass of Parnassus with its delicate green veins on white petals.
Completely waterlogged land (really a kind of marsh) may sometimes be managed as a type of grassland, called rush-pasture.
In rush-pasture, sharp-flowered rushes are often found with soft rushes and herbs like the purple flowered marsh thistle and, in western Scotland, whorled caraway, a fine-leaved plant with flowers similar to cow parsley. Cattle and sheep prefer to graze on the softer grasses, leaving the rush tussocks standing tall and untouched.
In some rush-pastures, purple moor-grass provides food and shelter for the caterpillars of the Scotch argus and chequered skipper and, in Argyll, of the rare marsh fritillary butterfly. Purple moor-grass is Britain’s only deciduous grass. Its leaves die completely in the winter to a pale-yellow litter and are prey to winter winds that bowl them along – hence its alternative name of ‘flying bent’ – until fences in its path become clogged and are blown down; a particular problem for farmers in winter.
The pith of soft rush was used to make rushlights – vegetable tapers of peeled rush soaked in fat – which burned to give a good clear light.
The chequered skipper is found where purple moor-grass grows. The caterpillar binds the edges of the grass-blade into a tube that protects it from predators and the worst of the weather. When selecting suitable plants upon which to lay their eggs, the adults choose locations where purple moor grass stays green into October or even November and avoid those where it dies back as early as September, but how they differentiate such locations is a mystery.
Some rush-pastures, with little human interference or management, have a profusion of colourful wildflowers throughout the summer: creamy meadowsweet, the purple northern marsh orchid and yellow balls of globe flowers in early summer and the drooping magenta heads of the melancholy thistle later in the year. Many of these flowers were once widespread in Scottish meadows, on land which may have been wrought from mires by drainage. With more intensive agricultural methods, they are but rarely seen in meadows now.
Meadowsweet, known variously as lady-of-the-meadow, meadow queen and queen-of-the-meadow, was used to flavour mead, for scouring milk churns, as a black dye, to treat malaria and to cover floors where, when crushed, it gave off a fresh carbolic smell.
Melancholy thistle, so called because the flower head droops at first, was used to ‘expel melancholy out of the body, and makes a man as merry as a cricket’.