Journal of Tropical Forest Science 24(2): 217–230 (2012) Neto V et al. 217 © Forest Research Institute Malaysia CONTRIBUTIONS OF FOREST BIOMASS AND ORGANIC MATTER TO ABOVE- AND BELOWGROUND CARBON CONTENTS AT AYER HITAM FOREST RESERVE, MALAYSIA V Neto*, N Ahmad Ainuddin, MY Wong & HL Ting Faculty of Forestry, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia Received March 2011 NETO V, AHMAD AINUDDIN N, WONG MY & TING HL. 2012. Contributions of forest biomass and organic matter to above- and belowground carbon contents at Ayer Hitam Forest Reserve, Malaysia. Three 0.1 ha forest plots in Peninsular Malaysia were studied for aboveground carbon from biomass and belowground carbon in the soil. Soil samples were collected from four layers for determination of colour, texture, bulk density and carbon with the carbon–nitrogen–sulphur analyser. Herbaceous plants were extracted from subplots and processed for determination of biomass and carbon of aerial parts and roots. Stem diameters of trees were obtained. Total carbon content in the soil decreased with depth from 1.86 (0–29 cm) to 0.81% (90– 120 cm), whereas bulk density in the same layers increased from 1.15 to 1.51 g cm -3 . The 60–120 cm layers contained 42% of the total carbon. The amounts of carbon found up to 120 cm depth, excluding large roots, superficial litter and coarse debris were 154, 174 and 208 t ha -1 in the three plots studied. Plots were very heterogeneous with regard to herbaceous vegetation, these contributing less than 0.01 t ha -1 carbon—main roots making up 30% and aerial parts being 3% richer. The three plots had 87, 195 and 205 t ha -1 of carbon from biomass of trees above the ground. Annual increments of litter, debris and root carbon were estimated. Keywords: Soil carbon, carbon storage, carbon sequestration, climate change, tropical forest NETO V, AHMAD AINUDDIN N, WONG MY & TING HL. 2012. Sumbangan biojisim hutan dan bahan organik terhadap kandungan karbon di bahagian atas dan bahagian bawah tanah di Hutan Simpan Ayer Hitam, Malaysia. Tiga plot hutan di Semenanjung Malaysia masing-masing bersaiz 0.1 ha dinilai kandungan karbon daripada biojisim di atas tanah dan karbon di dalam tanah. Sampel tanah diperoleh daripada empat lapisan untuk penentuan warna, tekstur, ketumpatan pukal dan karbon menggunakan penganalisis karbon–nitrogen–sulfur. Tumbuhan herba diperoleh daripada subplot dan diproses untuk menentukan biojisim dan karbon keseluruhan pokok dan akar. Diameter pokok juga diperoleh. Jumlah kandungan karbon di dalam tanah menurun dengan kedalaman iaitu dari 1.86% (0–29 cm) hingga 0.81% (90–120 cm) manakala ketumpatan pukal daripada lapisan yang sama meningkat dari 1.15 g cm -3 hingga 1.51 g cm -3 . Lapisan 60–120 cm mengandungi 42% daripada jumlah karbon. Jumlah karbon sehingga kedalaman 120 cm (tidak termasuk akar yang besar, sarap permukaan dan serpihan kasar) ialah 154 t ha -1 , 174 t ha -1 dan 208 t ha -1 dalam ketiga-tiga plot yang dikaji. Plot mempunyai tumbuhan herba yang heterogenus yang menyumbang kurang daripada 0.01 t ha -1 karbon—akar utama mengandungi sebanyak 30% kandungan karbon manakala bahagian atas tanah 33%. Ketiga-tiga plot mengandungi 87 t ha -1 , 195 t ha -1 dan 205 t ha -1 karbon daripada biojisim pokok di atas tanah. Kenaikan tahunan karbon daripada sarap, serpihan dan akar juga dianggarkan. *Present address: Agro-Biotechnology Institute, PO Box 341 UPM, 43400 Serdang, Selangor Darul Ehsan, Malaysia. E-mail: emirwati@gmail.com INTRODUCTION The concentration of atmospheric carbon dioxide (CO 2 ) in 2005 was approximately 36% higher than that in 1750 (IPCC 2007a). In 2009, the amount of CO 2 in the air was 387 ppm, with an annual rate of increase of about 1.4 ppm averaged over the 1960– 2005 period (NOAA/ESRL 2009). Atmospheric CO 2 is the greenhouse gas that contributes more to global warming compared with other greenhouse gases, ultimately leading to dramatic changes in the earth’s climate if the current trend is maintained (Gower 2003, Thomas et al. 2004, Tremblay et al. 2005). To stabilise the atmospheric content of CO 2 , thus mitigating climate change, it is necessary to preserve or improve the carbon sequestration and belowground carbon storage of tropical forests (IPCC 2007b).