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Scotland's Native Trees and Shrubs
Beware of biological invasion
Historically, the world's mountains, oceans and deserts presented formidable natural barriers to all but the hardiest plant and animal species. Distinctive ecosystems evolved in relative isolation.
Early human migration saw the first intentional introduction of non-native species as our ancestors attempted to satisfy physical and social needs, but the magnitude and frequency of those early introductions were minor compared to those associated with today's extensive global trade and human movement. History is rich with tales of the disastrous outcomes of intentional introductions such as Japanese knotweed which was introduced into the UK in 1825 as an ornamental shrub and is now a widespread nuisance. (Incidentally, every Japanese knotweed plant in the UK is genetically identical to the plant introduced in 1825 because it has never set seed but spreads vegetatively by underground stems called rhizomes.) More recently, in 1974, hedgehogs were rashly introduced to the island of Uist in the Hebrides. They now pose a major threat to ground nesting birds. The American mink's accidental escape from fur farms in the fifties is another example. It is now decimating seabird populations in Scotland's sea lochs and water vole populations around freshwater habitats elsewhere.
According to the World Conservation Union, today world wide non-native species invasion is second only to habitat loss as a cause of species endangerment and extinction.
We can avoid repeating such mistakes by learning from history. Before introducing non-native or alien species to any area, no matter how artificial or despoiled that area may be, consider the possible environmental consequences.
Could a new arrival have far-reaching repercussions or do permanent damage? Will something unique be lost forever?
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Ancient woodlands are rich in biodiversity and an important part of our natural heritage. They are helpless, priceless and irreplaceable in our lifetimes. We have a duty to look after them and the life they support. | Rhododendron has the power to destroy herbaceous vegetation and prevent all re-growth of other species. It must not be allowed to threaten our native woodlands. | Japanese knotweed ( Polygonum cuspidatum) is a particularly invasive alien and becoming a widespread nuisance. It has a deep root system that causes damage underground and tall vigorous, bamboo-like foliage that smothers shrubs and small trees. It can be controlled by the repeated application of a translocated herbicide absorbed through the foliage such as glyphosate ('Roundup') or a proprietary selective herbicide based on picloram that acts both through the foliage and the roots. |
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