15 TH INTERNATIONAL PEAT CONGRESS 2016 230 Abstract No: A-330 SPECIES COMPOSITION AND ENVIRONMENTAL FACTORS OF GRASSLANDS DEVELOPING ON THE BURNT PEATLANDS IN SUMATRA, INDONESIA Satomi Shiodera 1* , Kazuo Yabe 2 , Masayuki Itoh 1 , Osamu Kozan 1 , Tika Dewi Atikah 3 and Joeni Setijo Rahajoe 3 1 Center for Southeast Asian Studies (CSEAS), Kyoto University, Japan 2 Sapporo City University, Japan 3 Research Center for Biology, Indonesian Institute of Sciences (RCB-LIPI), Indonesia * Corresponding author:sshiodera@gmail.com SUMMARY In Sumatra, peat fire is a serious problem for the last two decades. It is a major cause of degradation that leads to loss of biodiversity and carbon stocks in peat swamp forests. After peat fire, grasslands will develop in the early successional stage there. To understand the relationship between grassland vegetation and environmental factors, field observations were conducted in Riau province, Sumatra, Indonesia. Fifty-one 2 × 2 m plots in the various grassland communities were set-up which spent several years after peat fire disturbance. Species compositions and coverage rates of all species in each plot were checked. The ground water levels were measured on October/December (wet season), 2014 and February (dry season), 2015. Groundwater sample was collected at the same time. In situ pH and electrical conductivity (EC) were measured by a compact pH and EC meter, respectively. In the laboratory, dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) concentrations were determined using a total organic carbon (TOC) analyzer. Forty five plant species were found from our plots (total 204 m2). There were only a few tree species were found in site that experienced fire, although many kinds of forb and grass species were found. They were seventeen forbs, eight grasses, nine ferns, nine shrubs and two trees. Dominant families were Asteraceae, Cyperaceae and Poaceae. Species composition seems to be decided by the groundwater level and water quality. Keywords: forest degradation, recovery, environmental impact assessment, anthropogenic disturbance, forest management INTRODUCTION Most of the tropical peatlands (24.8 Mha, 56 %) are found in the Southeast Asia region (47 % in Indonesia, 6 % in Malaysia, 3 % in Papua New Guinea, with small pockets and remnants in Brunei, Myanmar, the Philippines, Thailand and Vietnam) (Page et al. 2011). Tropical peat swamp forests are unique ecosystems, because of their extreme acidic, anaerobic and nutrient poor conditions. They support diverse forms of flora, fauna and microbes with manyendemic and endangered species. Anderson (1963) recorded 927 species of flowering plants and ferns in the peat swamp forests of Borneo. Most of tree families that are present in lowland dipterocarp forests are also presented in peat swamp forests, but many of species in peat swamp forests are specific to this habitat (Yule 2010, Rahajoe et al. 2016). The tropical peatland ecosystems sustain distinctive biodiversity and ecosystem values (Riely and Page 2005), and important refuges for many endangered species including orangutans. At the same time, tropical peatlands are one of the largest sink of organic carbon. The carbon is stored not only in the living biomass, but also in the peat soil. In Southeast Asia, their high carbon density results in a large regional peat carbon store of 68.5 Gt, equivalent to 77 % of the tropical and 11 – 13 % of the global peat carbon pools (Page et al. 2011). Indonesia has the largest stock of tropical peat carbon (57.4 Gt, 65%). This data is used to provide revised estimates for Indonesian forest soil carbon pools of 77 Gt, and total forest carbon pools (biomass plus soil) of 97 Gt. Peat carbon contributes 74 % to the total forest soil carbon pools in Indonesia. However, Indonesia is also the third largest emitter of greenhouse gases from peat fires. However, all regional peatlands are threatened by either logging, drainage, agricultural conversion (mostly to oil palm, as well as rice, rubber, coconut and pineapple), fire or other human activities. In Sumatra, peat fire has been a serious problem since the last decade. Peat fire is a major cause of peatland degradation that leads to loss of biodiversity and carbon stock in peat swamp forests. Analysis using Satellite Pour I‘Observation de la Terre (SPOT) image clarified that less than 4 % of peatland areas remain covered by intact peat swamp forests (PSFs), while 37 % are covered by PSFs with varying degree of degradation, and over 20 % is considered to be a un-managed degraded landscape, occupied by ferns, shrubs and secondary growth in Sumatra and Kalimantan (Miettinen et al. 2010). Peat swamp forests are sustained in the sensitive balance among deep water tables, canopy cover and leaf litter inputs (Yule 2010), causing difficulties in forest recovery after fire.