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The Vegetation of Exposed Sea Cliffs at South Stack, Anglessey, II. Experimental Studies / F. B. Goldsmith in Journal of Ecology, vol. 61, n°3 (Année 1973)

Public [article]  inJournal of Ecology > vol. 61, n°3 (Année 1973) . - pp. 819-829 Titre : The Vegetation of Exposed Sea Cliffs at South Stack, Anglessey, II. Experimental Studies Auteurs : F. B. Goldsmith, Auteur Année de publication : 1973 Article en page(s) : pp. 819-829 Langues : Anglais (eng) Catégories : [habitats/milieux] 18 - Côtes rocheuses et falaises maritimes [Thèmes] Ecologie [Thèmes] Végétation Mots-clés : pulvérisation de sel  communauté végétale  embrun salin Résumé : "The detailed investigation of a small area of cliff near South Stack, Anglesey, involved the collection of salt spray and a study of the temporal and spatial pattern of its deposition. Deposition was positively correlated with strong westerly winds, especially those over 30 knots. The amount of salt deposited depended primarily on height or distance from the sea and secondarily on local topographic features providing shelter or increasing exposure. Vegetational differences over the area intensively studied were considered to be due to the pattern of salt deposition and to differential rates of evaporation. The relationship between competition and salinity for maritime and inland species was investigated by selecting two species and growing them together in various proportions in a `de Wit' replacement series. Armeria maritima, the maritime species, had the competitive advantage under saline conditions but Festuca rubra, the inland one, had the advantage under non-saline conditions. Both species, however, produced the same yield when grown alone under both treatments. It is concluded that maritime cliff species have no salt requirement but, because they are slow-growing and semi-prostrate, they require an environment of low competitive intensity. Competition from inland species is reduced on exposed sea cliffs by high levels of soil salinity and foliar salt damage due to the incidence of salt spray during gales." (source : auteur) Type de publication : périodique Référence biblio : Goldmith F.-B., 1973 - The Vegetation of Exposed Sea Cliffs at South Stack, Anglessey, II. Experimental Studies. Journal of Ecology, 61 (3) : 819-829. ID PMB : 72233 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=72233 [article]

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• The Vegetation of Exposed Sea Cliffs at South Stack, Anglessey, I. The multivariate Approach / F. B. Goldsmith in Journal of Ecology, vol. 61, n°3 (Année 1973)

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The Vegetation of Exposed Sea Cliffs at South Stack, Anglessey, I. The multivariate Approach / F. B. Goldsmith in Journal of Ecology, vol. 61, n°3 (Année 1973)

Public [article]  inJournal of Ecology > vol. 61, n°3 (Année 1973) . - pp. 787-818 Titre : The Vegetation of Exposed Sea Cliffs at South Stack, Anglessey, I. The multivariate Approach Auteurs : F. B. Goldsmith, Auteur Année de publication : 1973 Article en page(s) : pp. 787-818 Langues : Anglais (eng) Catégories : [ZG] Royaume-Uni [habitats/milieux] 18 - Côtes rocheuses et falaises maritimes [Thèmes] Végétation Mots-clés : communauté végétale Résumé : "The vegetation of sea cliffs near South Stack, Anglesey, has been analysed using association-analysis and ordination. The data collected from sixty-five stands and seventy-seven species were exceptionally diverse and show wide ranges of stand richness and species abundance. They proved exacting for the techniques and provided an opportunity to comment on methodological weaknesses. Some simple coefficients and methods of axis construction failed to produce an ordination but Orloci's similarity coefficient and principal components analysis produced satisfactory results. This method was applied to three types of raw data matrices, i.e. using stands, species and environmental factors as individuals. Each yielded information not available from the others although the stand ordinations are considered the most useful. Different measures of species abundance and the effects of standardization have been compared and discussed. Ordination diagrams derived from frequency data were preferred to those from cover or presence/absence data. Standardization of the raw data by stands is recommended for data showing a range of richness when preparing stand ordinations and by species prior to constructing species ordinations. These standardizations reduce the effect of richness and abundance respectively. Association-analysis of these diverse data indicated several failings of the method. These include chaining which results from the exaggeration of χ2 values with rare species and species-poor stands, reversals of the hierarchy which result from the fact that χ2 max. is an unsuitable measure of class heterogeneity, and the arrangement of the final groups in order of richness (normal analysis) or abundance (inverse analysis). The results of the normal analysis were satisfactory but those of the inverse analysis were of little use. Association-analysis, due to its monothetic nature, often produces misclassifications so that some of the final classes need combining. The deletion of all rare species and species-poor stands is recommended prior to analysis. The over-riding importance of salinity as the major environmental factor was clearly demonstrated. However, stand richness and total plant cover may be used as indicators of competitive intensity. Their distribution on the ordination diagrams indicates that salinity acts indirectly on the maritime species through interspecific competition. The competitive ability of inland species is reduced by salt-spray and a saline soil so providing an environment suitable for the growth of sea-cliff halophytes. The importance of grazing and the influence of birds has also been discussed." (source : auteur) Type de publication : périodique Référence biblio : Goldsmith F.-B., 1973 - The Vegetation of Exposed Sea Cliffs at South Stack, Anglessey, I. The multivariate Approach. Journal of Ecology, 61 (3) : 787-818. ID PMB : 72234 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=72234 [article]

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