As far a we know, all the wild plant and animal life in the Highlands have colonized the area during the past 15,000 years. The bare debris of gravel left behind after the ice age was first clothed with vegetation characteristic of the Scandinavian tundra, mosses, scrubby willows and dwarf birches also hardy plants such as heather and crowberry.
In time a taller forrest of birch and juniper developed, and the trees of more temperate climates, such as Scots pine, oak, hazel, alder and ash, gradually spread in from the lowlands as the land mellowed under the warm post-glacial sun. When man first appeared as a hunter gatherer in the Highlands about 8,000 years ago, all except the highest and wettest land may have been covered with trees. The ‘Caledonian Forrest’ of Scots pine covered much of the drier soils of the eastern highlands.
In the milder, more humid climate of the west, oak dominated the lower slopes but in the harsher peatland landscape of the far north, woodland may have been confined to nooks of deep soil in the coastal glens. Sutherland and Caithness probably never supported much more than an open scrub of birch, juniper and willow.