Author: Fahselt, Dianne

Source: Canadian Journal of Botany, Volume 85, Number 10, October 2007 , pp. 1007-1017(11)

Publisher: NRC Research Press

Abstract:

Transplantation to new locations is used widely to propagate horticultural and agricultural species but is also promoted as a means of relocating whole communities that stand in the way of development. It may be used as well to move vegetation from the field for experimentation under controlled conditions. Transplantation has not in the past been considered a reliable means of conserving threatened species or reproducing functional characteristics of natural communities, and has been regarded by many as highly ineffective. However, its potential must now be re-examined because of the many recent transplant attempts as well as advances in related fields. Recent trials illustrate that individual endangered species are still particularly difficult to transplant and displaced multi-species sods are almost always changed in the process. Exact reconstruction of communities from individual components is next to impossible because the full complement of species, including critical microbial components, is almost never known. Owing to a limited understanding of phenology, reproduction, functional roles, and interrelationships among constituent microbes, cryptogams, vascular plants, and fauna, transplants may be placed into sites with both biological and physical insufficiencies. Genetic diversity may be lost or, if genotypes from diverse sources are mixed, outbreeding depression may result. Recent advances in soil science, microbial ecology, and population genetics have in some cases improved the effectiveness of transplantation, but new insights mainly permit a fuller appreciation of the causes of failure. Home-site advantage has been demonstrated, and habitat protection appears to be the best and perhaps only reliable way of preserving intact natural communities and rare species. Furthermore, experimentation with vegetational mats under controlled conditions may have little relevance to natural ecosystems.

On utilise souvent la transplantation sur de nouveaux sites pour propager les plantes et stabiliser les paysages perturbés, cependant plusieurs considèrent ce procédé hautement inefficace comme méthode fiable pour conserver les espèces menacées et les communautés naturelles. Tout de même, on doit réexaminer sa pertinence, compte tenu de nombreux essais récents de transplantation, ainsi que de progrès dans les domaines connexes. Dans des essais récents, on a constaté, que les espèces menacées demeurent particulièrement difficiles à transplanter, et que le patron des communautés en tapis d'espèces multiples, se modifie presque toujours au cours du processus. La reconstruction exacte des communautés, à partir des composantes individuelles frôle l'impossible parce que l'apport de la totalité des espèces, incluant les composantes microbiennes, demeure presque toujours un inconnu. Comme on comprend peu la phénologie, la reproduction, les rôles fonctionnels et les interrelations entre les microbes, les cryptogames, les plantes vasculaires et la faune, on peut placer les transplants sur des sites présentant des insuffisances biologiques et physiques. Au cours de la transplantation, on perd de la diversité génétique, et le mélange de génotypes provenant de diverses sources peu occasionner des dépressions d'hétérocroisement. Les sites perturbés par la transplantation offrent de plus des opportunités pour des espèces adventices agressives. Les progrès récents en pédologie, écologie microbienne et génétique des populations ont, dans certains cas, amélioré l'efficacité de la transplantation, mais les nouvelles perceptions ont surtout permis de meux identifier les causes des échecs. De plus, les expériences conduites avec des tapis de végétation sous des conditions contrôlées pourraient avoir peu de communes mesures avec les écosystèmes naturels.

Document Type: Commentary

Publication date: 2007-10-01

More about this publication?

• This journal changed title in 2007 and all issues from 2008 onwards can now be found at Botany

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