Quelles origines à l’asylvatisme des îles volcaniques australes Crozet et Saint-Paul (Terres Australes et Antarctiques Françaises, océan Indien) ?
Remote islands of Saint-Paul and Crozet (Indian Ocean) are among the most isolated islands in the world. Neither native trees nor shrubs have been reported on these Subantarctic Islands. Both regular and high wind speed that characterize these southern latitudes are considered the main factor to exp...
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Unité Mixte de Recherche 8504 Géographie-cités
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ftdoajarticles:oai:doaj.org/article:0f0e7d4415764ff9acb65f8373661675 2023-05-15T13:47:56+02:00 Quelles origines à l’asylvatisme des îles volcaniques australes Crozet et Saint-Paul (Terres Australes et Antarctiques Françaises, océan Indien) ? Sébastien Larrue Julien Chadeyron Frédéric Faucon 2018-01-01T00:00:00Z https://doi.org/10.4000/cybergeo.28917 https://doaj.org/article/0f0e7d4415764ff9acb65f8373661675 DE EN FR IT PT ger eng fre ita por Unité Mixte de Recherche 8504 Géographie-cités http://journals.openedition.org/cybergeo/28917 https://doaj.org/toc/1278-3366 1278-3366 doi:10.4000/cybergeo.28917 https://doaj.org/article/0f0e7d4415764ff9acb65f8373661675 Cybergeo (2018) biogeography island vegetation physical geography geohistory Geography (General) G1-922 article 2018 ftdoajarticles https://doi.org/10.4000/cybergeo.28917 2022-12-31T05:55:49Z Remote islands of Saint-Paul and Crozet (Indian Ocean) are among the most isolated islands in the world. Neither native trees nor shrubs have been reported on these Subantarctic Islands. Both regular and high wind speed that characterize these southern latitudes are considered the main factor to explain the origin of these treeless islands. However, this explanation seems unlikely because some southern islands in the “Roaring Forties” harbor many native woody species. In this article, we studied the insular context of Crozet archipelago and Saint-Paul island by means of eight geographic factors compared to 26 other Subantarctic Islands harboring native woody species or not. Factors used as potential predictors that may contribute to the naturally treeless island included island area (km²), island elevation (km), mean daily temperature (°C) and precipitation (mm), as well as the distance from the nearest continent (km), the distance to the nearest similar island (km), the distance to the Antarctic, and index of isolation (UNEP). Spearman’s rank correlation coefficient, stepwise regression analysis and bar diagrams were used to assess the relative influence of these factors on woody native species richness. Results show that the spatial pattern of woody species richness was significantly influenced by mean daily temperature (R² = 0.237, P = 0.014) with a threshold of treeless island phenomenon below ca. 6°C. However, seed dispersal abilities of woody southern species could play an important role to explain these naturally treeless islands. Principal Component Analysis (PCA) shows that the treeless phenomenon of Saint Paul cannot be explained by a “particular insular context” or low temperature. Shrubs were observed in 1626 and 1633 on the island of Saint Paul but volcanic activity in the late 17th century has potentially eliminated native trees on Saint Paul before the first botanical surveys were carried out. Article in Journal/Newspaper Antarc* Antarctic Antarctique* Saint-Paul Island Directory of Open Access Journals: DOAJ Articles Antarctic The Antarctic Indian Saint-Paul ENVELOPE(-57.715,-57.715,51.467,51.467) Cybergeo |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
German English French Italian Portuguese |
topic |
biogeography island vegetation physical geography geohistory Geography (General) G1-922 |
spellingShingle |
biogeography island vegetation physical geography geohistory Geography (General) G1-922 Sébastien Larrue Julien Chadeyron Frédéric Faucon Quelles origines à l’asylvatisme des îles volcaniques australes Crozet et Saint-Paul (Terres Australes et Antarctiques Françaises, océan Indien) ? |
topic_facet |
biogeography island vegetation physical geography geohistory Geography (General) G1-922 |
description |
Remote islands of Saint-Paul and Crozet (Indian Ocean) are among the most isolated islands in the world. Neither native trees nor shrubs have been reported on these Subantarctic Islands. Both regular and high wind speed that characterize these southern latitudes are considered the main factor to explain the origin of these treeless islands. However, this explanation seems unlikely because some southern islands in the “Roaring Forties” harbor many native woody species. In this article, we studied the insular context of Crozet archipelago and Saint-Paul island by means of eight geographic factors compared to 26 other Subantarctic Islands harboring native woody species or not. Factors used as potential predictors that may contribute to the naturally treeless island included island area (km²), island elevation (km), mean daily temperature (°C) and precipitation (mm), as well as the distance from the nearest continent (km), the distance to the nearest similar island (km), the distance to the Antarctic, and index of isolation (UNEP). Spearman’s rank correlation coefficient, stepwise regression analysis and bar diagrams were used to assess the relative influence of these factors on woody native species richness. Results show that the spatial pattern of woody species richness was significantly influenced by mean daily temperature (R² = 0.237, P = 0.014) with a threshold of treeless island phenomenon below ca. 6°C. However, seed dispersal abilities of woody southern species could play an important role to explain these naturally treeless islands. Principal Component Analysis (PCA) shows that the treeless phenomenon of Saint Paul cannot be explained by a “particular insular context” or low temperature. Shrubs were observed in 1626 and 1633 on the island of Saint Paul but volcanic activity in the late 17th century has potentially eliminated native trees on Saint Paul before the first botanical surveys were carried out. |
format |
Article in Journal/Newspaper |
author |
Sébastien Larrue Julien Chadeyron Frédéric Faucon |
author_facet |
Sébastien Larrue Julien Chadeyron Frédéric Faucon |
author_sort |
Sébastien Larrue |
title |
Quelles origines à l’asylvatisme des îles volcaniques australes Crozet et Saint-Paul (Terres Australes et Antarctiques Françaises, océan Indien) ? |
title_short |
Quelles origines à l’asylvatisme des îles volcaniques australes Crozet et Saint-Paul (Terres Australes et Antarctiques Françaises, océan Indien) ? |
title_full |
Quelles origines à l’asylvatisme des îles volcaniques australes Crozet et Saint-Paul (Terres Australes et Antarctiques Françaises, océan Indien) ? |
title_fullStr |
Quelles origines à l’asylvatisme des îles volcaniques australes Crozet et Saint-Paul (Terres Australes et Antarctiques Françaises, océan Indien) ? |
title_full_unstemmed |
Quelles origines à l’asylvatisme des îles volcaniques australes Crozet et Saint-Paul (Terres Australes et Antarctiques Françaises, océan Indien) ? |
title_sort |
quelles origines à l’asylvatisme des îles volcaniques australes crozet et saint-paul (terres australes et antarctiques françaises, océan indien) ? |
publisher |
Unité Mixte de Recherche 8504 Géographie-cités |
publishDate |
2018 |
url |
https://doi.org/10.4000/cybergeo.28917 https://doaj.org/article/0f0e7d4415764ff9acb65f8373661675 |
long_lat |
ENVELOPE(-57.715,-57.715,51.467,51.467) |
geographic |
Antarctic The Antarctic Indian Saint-Paul |
geographic_facet |
Antarctic The Antarctic Indian Saint-Paul |
genre |
Antarc* Antarctic Antarctique* Saint-Paul Island |
genre_facet |
Antarc* Antarctic Antarctique* Saint-Paul Island |
op_source |
Cybergeo (2018) |
op_relation |
http://journals.openedition.org/cybergeo/28917 https://doaj.org/toc/1278-3366 1278-3366 doi:10.4000/cybergeo.28917 https://doaj.org/article/0f0e7d4415764ff9acb65f8373661675 |
op_doi |
https://doi.org/10.4000/cybergeo.28917 |
container_title |
Cybergeo |
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1766248023643389952 |