Perte de compétitivité par adaptation au milieu physique: cas du Salix uva-ursi dans la toundra du Nouveau-Québec
Plant species of wind-exposed tundra sites are usually low lying and slow growing. Such a combination probably reduces competitive ability, perhaps to the point of limiting wind-tolerant species to sites with little or no competition, i.e., the most exposed sites, as if there were a trade-off betwee...
| Published in: | Canadian Journal of Botany |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Canadian Science Publishing
1988
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1139/b88-211 http://www.nrcresearchpress.com/doi/pdf/10.1139/b88-211 |
| Summary: | Plant species of wind-exposed tundra sites are usually low lying and slow growing. Such a combination probably reduces competitive ability, perhaps to the point of limiting wind-tolerant species to sites with little or no competition, i.e., the most exposed sites, as if there were a trade-off between adaptation to physical conditions and competitive ability. That hypothesis was tested with Salix uva-ursi Pursh, an arctic–alpine species common on windy sites in northern Quebec. Salix uva-ursi increases in abundance with exposure to wind, contrary to other species, but tolerates, even "prefers", the physical conditions found in sheltered sites. These two observations support the idea that interspecific competition limits the distribution of S. uva-ursi. However, the vigour of S. uva-ursi (number and size of shoots) is greatest in the sheltered sites, where the other species are more numerous and vigourous. This apparent contradiction between distribution and vigour could find an explanation in the temporal variations in climate. Under favourable conditions, prostrate and slow growth would be a handicap to S. uva-ursi, compared with other species, whereas under harsh conditions, species sensitive to wind and cold would suffer more than S. uva-ursi. [Translated by the journal] |
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