Structure and tree diversity of lowland limestone forest on Seram Island, Indonesia
There have previously been very few studies of forests on Seram Island in the Eastern Indonesian archipelago and none before on lowland limestone primary forests. The COLUPSIA project on collaborative land use planning has therefore chosen Seram as one of two project sites. The objective of the COLUPSIA project is to establish collaborative and equitable land use planning. In order to achieve its objective the COLUPSIA project aims to improve understanding of traditional resource management and how it interacts with governmental systems, as well as enhancing knowledge about tropical landscapes and ecosystem services.The aim of this study was to contribute to the COLUPSIA project through describing lowland limestone forest on Seram Island in respect to (1) forest structure, (2) tree species richness and (3) tree species composition. We set up 5 plots, each of 0.2 ha, at one site, Mawalai, and collected data on tree variables (tree diameter ?10 cm) as well as for some other life forms and environmental data. I made comparisons both within the Mawalai site and between sites, where I compared data from the Mawalai site with two 1 ha plots that were already set up at one site each, within the same forest type. Results varied depending on scale; tree species composition differed between some plots within one site, but much more between different sites where groupings per site were clear in NMS ordinations. Forest structure, in terms of diameter and stem density, differed between sites. A combination of the two, basal area, also varied within site. Species richness differed between one less species rich site (one 1 ha plot, 59 species) and the two other, more species rich sites (one 1 ha plot, 96 species and five 0.2 ha plots, 95 species), but did not differ significantly within the Mawalai site.Spatial distance and the amount of surface rock cover might explain a large portion of the variation seen both in between sites and between plots within site. It is however not possible to distinguish between the two in this study since they correlate and the rock cover gradient is insufficient. As one of few studies on limestone forest in Malesia this is also an example of what tree species might occur there. The distributions of tree species found in the study, based on a small sample, varied; some species have distributions towards New Guinea and Australia, others have Western distributions and some are restricted to the near region.