Environmental characteristics of tropical peat swamp forests and development of reforestation techniques for degraded peat land

在泰国，在该国最南部的那拉提瓦省可以找到天然泥炭沼泽森林（42,000公顷）。但是，最近，这些沼泽森林的广大地区迅速被开垦为农业用地。利用碳动力学方法估算了森林砍伐或开垦对天然泥炭沼泽森林的影响。泥炭沼泽原生林和次生林的年净碳吸收量分别为5.32tC/ha/年和5.22 tC/ha/年。假设次生林地表常年处于涝渍状态，预计净碳吸收量为9.69 tC/ha/年。另一方面，假设次生林土壤全年保持干燥，预计净碳排放量为-0.40 tC/ha/年。测定了天然泥炭沼泽森林中泥炭和凋落物分解和树木呼吸的二氧化碳排放量。按碳重计算，森林生态系统年CO_2排放量为8.84tC/ha/年。利用GPS定位技术对巴朔沼泽泥炭层厚度的水平分布进行了研究。估计泥炭层的平均厚度为1.1m。结果表明，厚泥炭层与海岸线平行，呈条状分布。开发区泥炭沉降量为2.72 ~ 5.21cm/年。这意味着生态系统排放16.1 ~ 30.8 tC/ha/年，即通过森林砍伐或开垦从碳汇转变为碳源。这些结果表明，水管理在次生林排水开发后，对限制泥炭分解和保持森林作为碳汇生态系统具有重要意义。在泥炭沼泽和酸性硫酸盐土壤中发现了一些有潜力种植的树种，如千层树等。

In Thailand, natural peat swamp forests (42,000ha) can be found in Narathiwat, the extreme south province of the country. But, recently, the wide area of these swamp forests reclaimed rapidly for agriculture. The effects of deforestation or reclamation for natural peat swamp forests were estimated with carbon dynamics. The annual amounts of net carbon absorption were estimated at 5.32tC/ha/year and 5.22 tC/ha/year for the primary peat swamp forest and the secondly forest, respectively. A great amount of net carbon absorption, 9.69 tC/ha/year, was expected, assuming that the ground surface in the secondary forest remained under waterlogged conditions throughout a year. On the other hand, a net emission of carbon, -0.40 tC/ha/year, was expected, assuming that the soil in the secondary forest remained under dry conditions throughout a year. Carbon dioxide emissions by peat and litter decomposition and by tree respiration were measure in natural peat swamp forest. Annual CO_2 emission from the forest ecosystem was estimated to 8.84tC/ha/year on the carbon weight basis. The horizontal distribution of thickness of peat layer at Bacho swamp was investigated with the assistance of GPS for localization. It was estimated that the average thickness of peat layer was 1.1m. It was clarified that thick peat layer located parallel to coastal line with striped pattern. Peat subsidence of the development zone was 2.72〜5.21cm/year. This means that the ecosystem emits 16.1〜30.8 tC/ha/year, that is to change from a carbon sink to carbon source by the deforestation or reclamation. These results show that water management is quite important for the secondary forest after development with drainage, to restrict peat decomposition and keep the forest as a carbon sink ecosystem. Some tree species (Melaleuca cajuputi, etc.) were found as promising species to be planted at peat swamp and acidic sulfate soil.