Philip Burton in his reply to Rob Bennett asked about experiences with exoitic trees elsewhere in the world. > > I'd be curious to hear different perspectives about the costs and > benefits of exotic introductions: Eucalyptus in southern Africa, > Pinus radiata in New Zealand, P. contorta in Sweden, Sitka spruce > in Scotland, and Douglas-fir throughout Europe....has it been > worthwhile? > The experience in NZ with introduced plants in general has been one of rapidly increasing conservation problems. Already c. 50% of our wild flora is comprised of naturalised species, and this figure is increasing. Most of the new introductions are coming into NZ as horticultural plants, and spreading from gardens etc. NZ of course has a large forestry estate dominated by exotic species, especially radiata pine. Several conifers, predominantly North American, are now starting to create problems in some areas of NZ. the main species Pinus contorta, pinus nigra, Pinus radiata, Pseudotsuga menziesii and Larix decidua. Most will not persist in native forests 9although Douglas fir may be an exception), but they are rapidly invading largely natural grassland and shrubland communities, resulting in total replacement of native species. The problems are most severe in the central North Island and the drier eastern South Island, where large amounts of $$ are being spent annually trying to control, these species. One of the key problems with these invasive conifers is that at present virtually no one is accepting responsibility - so the future is uncertain. There is also a suggestion that they shoul dbe used as a wood resource, but this is being strongly challenged on the grounds that they are seriously affecting ecological and aesthetic values. In summary, the short answer to the question is be VERY cautious with introductions of new species. Regards, David Norton Dr David A. Norton Conservation Research Group School of Forestry University of Canterbury Private Bag 4800 Christchurch, New Zealand Ph: +64-3-364-2116 Fax: +64-3-364-2124 E-mail: d.norton@fore.canterbury.ac.nz
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