A revision of mangrove plants of the Solomon Islands, Vanuatu, Fiji, Tonga and Samoa

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A revision of mangrove plants of the Solomon Islands, Vanuatu, Fiji, Tonga and Samoa.

This report documents and reviews the results of plant diversity surveys of mangrove vegetation
conducted during 2012 by Dr Norm Duke in collaboration with five MESCAL country teams in
Solomon Islands, Vanuatu, Fiji, Tonga and Samoa. Work in each country involved team training,
support and consultation, as well as the compilation and preliminary review of data gathered.
2) Data presented in this report includes species keys and checklists for each country, noting a
number of significant new discoveries for most. Success was measured not only by these new
findings, but also by the enthusiasm, skills and confidence shown by each country work team.
3) The data provide essential pre-requisite information for subsequent vegetation surveys on
biomass, carbon accumulation, and the condition of mangrove tidal wetlands of each country.
4) The number of mangrove species observed in all countries totalled 34 species, with 6 of these
being hybrids. No single country had all species.
5) Mangrove species in the islands vary with: Samoa having 5; Tonga having 10; Fiji having 11;
Vanuatu having 21; and Solomon Islands having 31. These numbers have something to do with the
proximity to Papua New Guinea and SE Asia (as the world region with maximal mangrove
diversity), but it has more to do with island size where smaller islands have less species.
6) It was notable that hybrids only occurred where both parental species grew in nearby locations.
The hybrid intermediate forms are considered recognisable species in the list because they are a
notable and distinctive in the field, and they maintain the same morphological characters
consistently wherever they occur.
7) The species are from 18 genera, representing 14 different plant families. This is very high diversity
in such a small plant habitat group. The most well-represented family is the Rhizophoraceae with
13 species and hybrids, while the second is the Acanthaceae family with 5, and the Lythraceae with
4. The next items list the number of species additional to those recorded in the 2010 World
Mangrove Atlas.
8) There are 8 additional species observed for Solomon Islands, including: Acanthus ebracteatus
subsp. ebracteatus; Acrostichum aureum; Acrostichum speciosum; Avicennia rumphiana;
Barringtonia racemosa; Bruguiera hainesii; Dolichandrone spathacea; Pemphis acidula. At least
two additional mangrove species require confirmation as they may also occur in the Solomon
Islands, including: Cynometra iripa; Rhizophora annamalayana.
9) There are 3 additional species observed for Vanuatu, including: Acrostichum speciosum;
Dolichandrone spathacea; Rhizophora selala. At least 3 additional mangrove species require
confirmation as they may also occur in Vanuatu including: Acanthus ilicifolius; Pemphis acidula;
Rhizophora tomlinsonii.
10) There are 2 additional species observed for Fiji, including: Barringtonia racemosa; Rhizophora
stylosa. The latter record was clearly an error in the World Mangrove Atlas because the species is
well known in the islands. At least two additional mangrove species require confirmation as they
may also occur in Fiji, including: Acrostichum speciosum; Pemphis acidula.
11) Two additional species observed for Tonga, including: Acrostichum speciosum; Rhizophora selala.
12) One additional species observed for Samoa, including: Acrostichum speciosum. At least one
additional mangrove species requires confirmation as it may also occur in Samoa, included
Pemphis acidula.