Ecological effects of introduced tree species in Britain

Non-native trees have been introduced to Britain and native trees have been redistributed for over 2000 years, but most species were introduced in the last 400 years, and the ecological consequences have not yet been fully manifested. Introduction has been followed by various forms of adaptation to British conditions: (i) genetic changes in the trees themselves, (ii) assimilation into forest communities, (iii) colonisation by native plants, animals and fungi and (iv) gradual cultural acceptance. Nevertheless, some naturalised shrubs are widely regarded as ecologically damaging in semi-natural vegetation (e.g. Rhododendron ponticum, Acer pseudoplatanus), and the introduction of non-native conifers has allowed forestry to expand over moorland with substantial ecological effects. (C) 2001 Elsevier Science B.V. All rights reserved.