Institut Agronomique néo-Calédonien (IAC), Diversité biologique et fonctionnelle des écosystèmes terrestres, Nouméa, New Caledonia.
Institut de Recherche pour le Développement (IRD), UMR AMAP, Nouméa, New Caledonia.
Ann Bot. 2018 Jan 25;121(1):25-35. doi: 10.1093/aob/mcx107.
The biodiversity hotspot of New Caledonia is globally renowned for the diversity and endemism of its flora. New Caledonia's tropical rainforests have been reported to have higher stem densities, higher concentrations of relictual lineages and higher endemism than other rainforests. This study investigates whether these aspects differ in New Caledonian rainforests compared to other high-diversity rainforests in the Southwest Pacific.
Plants (with a diameter at breast height ≥10 cm) were surveyed in nine 1-ha rainforest plots across the main island of New Caledonia and compared with 14 1-ha plots in high-diversity rainforests of the Southwest Pacific (in Australia, Fiji, Papua New Guinea and the Solomon Islands). This facilitated a comparison of stem densities, taxonomic composition and diversity, and species turnover among plots and countries.
The study inventoried 11 280 stems belonging to 335 species (93 species ha-1 on average) in New Caledonia. In comparison with other rainforests in the Southwest Pacific, New Caledonian rainforests exhibited higher stem density (1253 stems ha-1 on average) including abundant palms and tree ferns, with the high abundance of the latter being unparalleled outside New Caledonia. In all plots, the density of relictual species was ≥10 % for both stems and species, with no discernible differences among countries. Species endemism, reaching 89 % on average, was significantly higher in New Caledonia. Overall, species turnover increased with geographical distance, but not among New Caledonian plots.
High stem density, high endemism and a high abundance of tree ferns with stem diameters ≥10 cm are therefore unique characteristics of New Caledonian rainforests. High endemism and high spatial species turnover imply that the current system consisting of a few protected areas is inadequate, and that the spatial distribution of plant species needs to be considered to adequately protect the exceptional flora of New Caledonian rainforests.
新喀里多尼亚的生物多样性热点地区以其植物区系的多样性和特有性而闻名于世。据报道，新喀里多尼亚的热带雨林具有比其他热带雨林更高的茎密度、更多的残余谱系和更高的特有性。本研究旨在调查与其他西南太平洋高多样性雨林相比，新喀里多尼亚雨林在这些方面是否存在差异。
在新喀里多尼亚主岛的 9 个 1 公顷的雨林样地中，对胸径≥10cm 的植物（下同）进行了调查，并与西南太平洋（澳大利亚、斐济、巴布亚新几内亚和所罗门群岛）的 14 个 1 公顷的高多样性雨林样地进行了比较。这便于对样地和国家之间的茎密度、分类组成和多样性以及物种更替进行比较。
本研究共记录了新喀里多尼亚的 11280 株 335 种植物（平均每公顷 93 种）。与西南太平洋的其他雨林相比，新喀里多尼亚的雨林具有更高的茎密度（平均每公顷 1253 株），包括丰富的棕榈科植物和树蕨科植物，后者的高丰度在新喀里多尼亚以外是无与伦比的。在所有样地中，残余物种的密度（茎和种）均≥10%，各国之间没有明显差异。物种特有性平均达到 89%，在新喀里多尼亚显著较高。总的来说，物种更替随地理距离的增加而增加，但在新喀里多尼亚样地之间没有增加。
因此，高茎密度、高特有性和大量胸径≥10cm 的树蕨科植物是新喀里多尼亚雨林的独特特征。高特有性和高空间物种更替意味着，由少数保护区组成的现有系统是不够的，需要考虑植物物种的空间分布，以充分保护新喀里多尼亚雨林的特有植物。
