Seed rain into a degraded tropical peatland in Central Kalimantan, Indonesia Grace V. Blackham a,⇑ , Andri Thomas b , Edward L. Webb a , Richard T. Corlett a,1 a Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore b Jalan Panenga Raya, Kereng Bangkarai, Palangka Raya, Kalimantan Tengah, Indonesia article info Article history: Received 25 March 2013 Received in revised form 6 August 2013 Accepted 11 August 2013 Keywords: Seed dispersal Peat Southeast Asia Indonesia Degradation Regeneration abstract Forested tropical peatlands in Southeast Asia are important as global carbon stores and for biodiversity conservation yet are being rapidly converted to agriculture or degraded into fire-prone non-forest vege- tation. Although large areas have been abandoned, there is little evidence for the subsequent recovery of forest. As part of a study of forest degradation and recovery, we assessed seed rain into an area of non- forest regrowth in degraded tropical peatland in the former Mega Rice Project: an abandoned attempt to convert 1 million hectares of tropical peatland for rice production in Central Kalimantan, Indonesia. Fifty seed traps were placed in the open and fifty under trees. Seeds were collected every 15 ± 3 days for 1 year. Seed rain and foreign seed rain (species different from the tree over the trap) was higher for traps under trees (1127.8 seeds and 465.0 seeds m À2 y À1 respectively) than for traps in the open (95.2 seeds m À2 y À1 ). Foreign seed rain consisted largely of species that also grow in mature forest, but was dominated by a few abundant wind-dispersed species (particularly from the woody liana, Uncaria elliptica, and the tree, Com- bretocarpus rotundatus) and the majority of animal-dispersed foreign seeds were found under trees. While seed rain both in the open and under trees appears sufficient for the development of woody plant cover, diversity will be limited in the early stages of succession. We recommend enrichment planting with species that would have been present before forest destruction but are not represented in the cur- rent seed rain. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction While recent global attention has focused on the high carbon content of peat soils and the potential role of tropical peatlands in climate change (Page et al., 2011), tropical peatlands have long been important at a regional level as water catchment and control systems, and as food, fuel and shelter resources for local communi- ties (Rieley et al., 1996). They are also important habitats for a di- verse range of fauna (Cheyne and Macdonald, 2011; Posa, 2011; Posa et al., 2011; Yule, 2010) including endangered species such as the Bornean orang-utan (Pongo pygmaeus)(Morrogh-Bernard et al., 2003; Wich et al., 2008) and Bornean agile gibbon (Hylobates albibarbis)(Buckley et al., 2006; Cheyne et al., 2008). Of all the countries containing tropical peatland, the largest proportion is found in Indonesia, covering an area of 206,950 km 2 (Page et al., 2011). However, in the last few decades much of this naturally for- ested land has been exploited and developed, with areas undergo- ing large-scale drainage and clearance for agriculture, or being subjected to logging (Rieley et al., 1996; Yule, 2010). Of the original peatland in Indonesia and Malaysia, 58% of the area has been deforested and a third of this deforested area exists as degraded secondary regrowth (Miettinen and Liew, 2010). The most exten- sive degraded peatlands in Indonesia are located in the provinces of Riau and Jambi in Sumatra and Central, East and South Kaliman- tan in Indonesian Borneo (Hooijer et al., 2006). Land-cover change studies have found that areas of tropical peatlands classed as sec- ondary regrowth twenty years ago remain in the same state today (Miettinen and Liew, 2010), that is, fern- and sedge-dominated landscapes with very few or no trees (Page et al., 2009). This may be due to any of a number of filters that can limit the pro- cesses of natural regeneration, including seed dispersal limitation. Degraded tropical peatlands in Southeast Asia largely consist of vast deforested and degraded areas that extend several kilometres (and across physical barriers) from the nearest relatively intact for- est seed source (Hooijer et al., 2006; Miettinen et al., 2011). Indeed, intensive exploitation of forest resources has led to large areas of degraded land in much of tropical Asia (Chokkalingam et al., 2001), an example of which is Imperata ‘mega-grasslands’ (Garrity et al., 1996). Due to the high cost of replanting (Erskine, 2002), res- toration efforts in expansive degraded areas will also be dependent on natural regrowth (Chazdon, 2008; Lamb et al., 2005). However, 0006-3207/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.biocon.2013.08.015 ⇑ Corresponding author. Tel.: +44 1214444046. E-mail address: graceblackham@gmail.com (G.V. Blackham). 1 Present address: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, 666303 Yunnan, China. Biological Conservation 167 (2013) 215–223 Contents lists available at ScienceDirect Biological Conservation journal homepage: www.elsevier.com/locate/biocon