Plant species coexistence in cliff habitats

• Published in: Journal of Biogeography
• Main Author: Cooper, Alan
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1997
• Subjects: Arctic
• Online Access: http://dx.doi.org/10.1111/j.1365-2699.1997.00128.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2699.1997.00128.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2699.1997.00128.x

An ecological analysis of the ledge and crevice vegetation of cliffs in north‐east Ireland was carried out using a sampling programme based on multivariate land classification. The composition of the vegetation was shown to be determined primarily by distance from the sea, elevation and rock type. The chemical composition and physical structure of the cliffs, together with environmental gradients associated with aspect, elevation and nearness to the sea provide a wide range of habitats in which plants coexist. Certain types of cliff vegetation contained associations of species with a contrasting ecology, such as arctic–montane, maritime, woodland, calcicole and calcifuge plants. The positions of these species in ordination space were found to be unique but overlapping. A model is described to account for these observations. It proposes that species dominance in cliff habitats is prevented by factors such as physical disturbance and that plants are able to coexist in cliff habitats which meet their common environmental tolerances and preferences. The model predicts that cliff habitats with the greatest diversity of species are likely to be subject to less extremes of environmental variability. These habitats include inland sites with nutrient enrichment by sea spray, north‐facing sites, seepage sites, base‐rich sites, low elevation sites and sites with a heterogeneous physical structure.