Forest Ecology Research in Borneo: 2003-2008
Brearley, Francis Q., Borneo Research Bulletin
Borneo is the second largest tropical island in the world (after New Guinea). It has one of the most diverse floras, with around 14,400 plant species (Roos et al. 2004), of which around 3,000 are trees (MacKinnon et al. 1996). Around 30 % of all plant species are found nowhere else (Roos et al. 2004). In addition, Borneo is the center of diversity of the important timber tree family, the Dipterocarpaceae, where at least 267 species are found (Ashton 1982). Lambir Hills in northwestern Sarawak has the highest density of tree species in the world, with 1,173 tree species (in 286 genera and 81 families) in only a 0.52 [km.sup.2] area of forest (Lee et al. 2002) and in the environs of Mount Kinabalu in Sabah there are over 5000 plant species (Beaman 2005). In terms of conservation priorities, Borneo falls within the Sundaland biodiversity hotspot, one of the five hottest hotspots (Myers et al. 2000), is split between two of the world's seventeen megadiverse countries (Mittermeier et al. 1997), and harbors four of the "Global 200" priority regions for conservation (Olson & Dinerstein 2002). By any measure, Borneo is exceptionally biodiverse.
My aim in this review is to present ecological work that has been carried out on Borneo in the period 2003 to 2008 with a particular locus on forest ecology. "Forest ecology" covers a number of topics and i will consider here mostly terrestrial plant ecology in a broad sense (I will not examine animal ecology in any detail). The topics which I feel are most worthy of my attention, and which I have knowledge to comment upon, are focused upon here under the following groupings: (i) floristics, i.e. descriptions of plant communities with a view to examining larger-scale patterns of species diversity on the island, (ii) new plant species that have been discovered and described, (iii) community ecology, with a focus on habitat specialization of tree species. I will then look at (iv) rates, patterns and drivers of deforestation with some thoughts on forest conservation and (v)the effects of disturbance on the forest and patterns of recovery. I will finish with a (vi) section on biogeochemistry and carbon (C) storage in Borneo's forested ecosystems and how C storage might be affected by some of the geographical variations and disturbances noted previously. My focus will be on studies conducted in the forests of Borneo but will include those which have a wider ecological significance. Figure I shows the location of the sites mentioned in the text. It is notable, and of some concern, that the majority of the studies reported here have the main authors primarily based in Europe, America, or Japan; where local authors are included they are often as research counterparts rather than primary authors. In terms of capacity building, it would be great to see local authors publishing their work in the higher-impact international journals (although there is the other side of the coin, these journals are often too expensive to subscribe to in the region).
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New descriptions of tree communities (from permanent plots where trees over a certain diameter are marked and identified) have been published from Barito Ulu and Wanariset Sangai in Central Kalimantan (Brearley et al. 2004; Wilkie et al. 2004), Belalong in Brunei (Small et al. 2004); Sungai Wain in South Kalimantan (Eichhorn & Silk 2006); and CIFOR's Malinau Reseach Forest in East Kalimantan (Kartawinata et al. 2006). When considered together in combination with other plot descriptions, these studies form a larger body of work and their value is increased considerably as species distributions and large-scale patterns of variation in tree communities can be ascertained. For example, Silk et al. (2003) collated data on tree species abundance from 28 locations across Borneo and showed that tree diversity was highest in southeast Kalimantan and central Sarawak. Furthermore, the forests of Borneo could be divided into five floristic groups using statistical clustering methods and those groups which were north of the central mountain range were clearly different from those to the south, suggesting that the mountains effectively prevent large-scale dispersal of many tree species (Silk et al. …