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- Title
The potential for long-term persistence of forest fragments on Tongatapu, a large island in western Polynesia.
- Authors
Wiser, Susan K; Drake, Donald R; Burrows, Larry E; Sykes, William R
- Abstract
Aim We describe compositional variation among forest fragments on Tongatapu in terms of successional status and site conditions. We then examine two factors that directly influence the potential for long-term persistence of these fragments — tree regeneration and alien invasion. Location Tongatapu is the largest (261 km²), most densely inhabited (population 67,000) island in the Kingdom of Tonga, western Polynesia. Inhabited for 3000 years, it is now more than 90% deforested. Methods We mapped land cover from 1990 aerial photographs and sampled forest fragments and selected regenerating (late bush fallow) stands. Composition data from forest fragments were analysed with cluster analysis and ordination, and then an environmental framework was constructed to allow floristic comparisons between these and late bush fallow stands. We analysed size-structures of tree populations to evaluate regeneration. Distribution patterns of aliens introduced by Polynesian settlers (ancient introductions) and after European contact (modern introductions), were compared. Growth forms were compared to determine whether aliens are qualitatively distinct from the native forest fragment flora. Correlation analysis and hierarchical regression determined whether factors such as disturbance, soil fertility, species richness, fragment size, and distance to forest margin, which influence invasion patterns elsewhere, were important on Tongatapu. Results Forest fragments occupy 3.2% of the land area; regenerating 'bush fallow' stands occupy 7.9%. We recorded 209 vascular plant species, half of which were trees or shrubs; other growth forms were, in decreasing order of importance, forbs, lianes and vines, graminoids and ferns. Eight per cent of the species were ancient introductions and 33% were modern introductions. Forest fragments were classed into four types: interior, coastal, Excoecaria coastal swamp and Inocarpus coastal swamp — the latter two unknown elsewhere in...
- Subjects
TONGA; TONGATAPU Island (Tonga); FRAGMENTED landscapes; FORESTS &; forestry; REGENERATION (Botany); BIOLOGICAL invasions
- Publication
Journal of Biogeography, 2002, Vol 29, Issue 5/6, p767
- ISSN
0305-0270
- Publication type
Article
- DOI
10.1046/j.1365-2699.2002.00723.x