Annals of Botany 92: 31-40, 2003
© 2003 Annals of Botany Company
The Plant Communities and Environmental Gradients of Pitcairn Island: The Significance of Invasive Species and the Need for Conservation Management
1 Department of Botany, Trinity College, Dublin 2, Ireland and 2 Trinity College Botanic Gardens, Dublin 6, Ireland
* For correspondence. Fax +353 1 6081147, e-mail nkingston{at}duchas.ie
Received: 20 November 2002; Returned for revision: 21 January 2003; Accepted: 7 March 2003
Quantitative surveys of the vegetation of south-east Polynesian Islands are rarely undertaken owing to time and logistical restrictions; however they are fundamental in determining the conservation status of fragile island ecosystems. The aim of the research was to document quantitatively the vegetation of Pitcairn Island by investigating whether clearly definable plant communities existed on the island, and the underlying environmental gradients influencing these communities. Initially, 10 x 10 m quadrats were taken from all areas of the island, with environmental parameters recorded for each quadrat. The vegetation was then mapped from high altitude vantage points. Two-way indicator species analysis was used to identify distinct plant communities, and canonical correspondence analysis was used to determine the underlying environmental gradients. The vegetation consists of 14 plant communities: four coastal, six forest, two fernland and two scrub communities. Large areas are covered by non-native scrub vegetation, and by monospecific Syzygium jambos (rose-apple) plantations. Less than 30 % of the island is covered by native forest, and these areas are limited to remote valleys. Fernlands also cover large areas, including both eroding areas and ridge tops. Coastal vegetation comprises rock and cliff communities with limited strand vegetation. The major environmental gradient affecting the composition of the plant communities is altitude, but anthropogenic influences also have a large effect, owing to forest clearance and introduced species. The light environment is affected by the canopy species, and determines what ground flora can develop. Identification of distinct plant communities has allowed for a system of nature reserves to be suggested, which conserve all of these plant communities and a significant proportion of the threatened plant species.
Key words: CCA, canonical correspondence analysis, classification, conservation, invasive species, islands, multivariate analyses, ordination, south-east Polynesia, TWINSPAN, two-way indicator species analysis, vegetation description, vegetation mapping.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  Z.-S. WANG, S.-Q. AN, H. LIU, X. LENG, J.-W. ZHENG, and Y.-H. LIU Genetic Structure of the Endangered Plant Neolitsea sericea (Lauraceae) from the Zhoushan Archipelago Using RAPD Markers Ann. Bot., January 2, 2005; 95(2): 305 - 313. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. PARISOD, C. TRIPPI, and N. GALLAND Genetic Variability and Founder Effect in the Pitcher Plant Sarracenia purpurea (Sarraceniaceae) in Populations Introduced into Switzerland: from Inbreeding to Invasion Ann. Bot., January 2, 2005; 95(2): 277 - 286. [Abstract] [Full Text] [PDF]
|
|