Walking on Harris and Lewis. Richard Barrett

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      Four seasons in one May morning on Oireabhal – snow, then hail followed by sun and eventually a shower (Walk 13)

Flowers and vegetation

      Pollen grains preserved within the peat bogs indicate that, following the ice ages, the terrain on these islands was colonised by a pioneer community of sub-alpine herbaceous plants and low shrubs. This was followed by heather, juniper and grass and subsequently, around 8000 years ago, by trees such as birch, hazel and oak. Large pieces of ‘bogwood’ are occasionally uncovered under the peat layer and indicate that Harris and Lewis once had more trees and shrub cover than they do today. This is particularly evident in Marbhig in the North Lochs area of Lewis where tree stumps are regularly unearthed.

      Man’s need for wood and land for cultivation together with the overgrazing caused by an overpopulation of sheep and deer are traditionally blamed for the lack of trees, but it is more complex than that. The ‘natural decline’ model describes a shift to a wetter, cooler climate a few thousand years ago which caused peat layers to build up, engulfing woodlands and making it increasingly difficult for seeds to germinate in the waterlogged conditions, thus reducing the amount of land suitable for trees to grow. The grazing pressure of the large populations of sheep and deer prevents trees and scrub from re-establishing themselves anywhere outside of the steep ravines and fenced-off plantations where they are found today.

      About 12–15 per cent of the Scottish deer population is culled each year, providing income from commercial stalking and venison for the table. Being totally free-range and expertly dispatched in a micro-second, it could be argued that it is the perfect meat for human carnivores with concerns for animal husbandry. However, research suggests that only a sustained annual cull of around 80 per cent would restore the balance between the vegetation and deer and allow trees once again to colonise. Where this has been practised, such as on the slopes of Creag Meagaidh in the Central Highlands, the effect on the ecology has been profound. In little more than a decade the area of woodland has spread tenfold with seedlings of birch, rowan, willow, aspen and oak, resulting in an associated increase in birdlife, flora and invertebrates and creating a biodiversity not seen for many centuries. With careful consideration for the livelihoods of those engaged in deer husbandry and stalking, the same could be achieved in parts of Harris and Lewis, and would transform the landscape.

      But the islands are far from barren, with the hills, moors and beaches presenting a wide variety of habitats for plant life. Most plants are small and need searching out, like the delicate alpines or the 150 or so species of mosses and liverworts that occur on the rocky hillsides. But when they erupt in mass flowering the islands become spectacular, and the highlight of the year is when the machair – the ‘shell meadow’ behind the dunes – is carpeted with wild flowers during the summer months. Most of the plants are commonplace – ragwort, buttercup, clover, daisy, various vetches and trefoils and, in later months, rarer orchids – but collectively the effect is unforgettable. The best places to see this are on the west coasts of South Harris and the Uig area of West Lewis.