东北林区森林凋落物中的有机酸分析

落叶松(Larixolgensis)、水曲柳(Fraxinusmandshurica)、红松(Pinuskoraiensis)、白桦(Betulaplatyphylla)是东北林区主要造林树种。于2002年10月初,在东北林业大学帽儿山实验林场老爷岭和尖砬沟试验站(45?2?45?0碞,127?0?127?8碋)采集了4个树种林分的森林凋落物样品。采用气相色谱法对当年新鲜凋落物及半分解凋落物中有机酸进行了定性、定量分析。鉴定出13种有机酸,包括草酸、丙二酸、反丁烯二酸、丁二酸、顺丁烯二酸、苹果酸、柠檬酸、棕榈酸、硬脂酸、油酸、亚油酸、亚麻酸、花生酸。结果表明:对于新鲜凋落物而言,所测的7种低分子量有机酸中草酸含量最大,一般高于30mg/g;6种高级脂肪族酸中油酸或亚油酸含量最大,高于40mg/g;在半分解凋落物中,草酸含量最多,其次为亚油酸,再次为油酸;同一树种新鲜凋落物中有机酸种类和含量明显多于半分解凋落物。图5表2参10。

Analysis of organic acids in selected forest litters of Northeast China

Larch (Larix olgensis), Manchurian ash (Fraxinus mandshurica), Korean pine (Pinus koraiensis) and White birch (Betula platyphylla) are the major planting species in northeast China. The samples of forest litters were collected from the stands of the above 4 species in Laoyeling and Jianlagou experiment stations of Maorshan Exp. Forest Farm (45?2-45?0N, 127?0-127?8E), Northeast Forestry University, in early October 2002. Quantitative analysis and qualitative analysis were carried out on the organic acids existing in freshly fallen litters (L layer) and hemi-decomposed litters (F layer) of the four forest species by using Gas Chromatogram system. A wide variety of organic acids were identified, including oxalic, malonic, fumaric, succinic, maleic, malic, citric, C16:0, C18:0, C18:1, C18:2, C18:3 and C20:0 acids. In respect of L litters of all samples, the oxalic acid content (over 30 mg/g) was the highest of the seven low-molecular-weight organic acids identified, while the content of oleic or linoleic (above 40 mg/g) was found to be highest among the six high aliphatic acids identified. As to F litters, oxalic acid content was also the highest, followed by linoleic and oleic. For the same tree species or the same forest, the kinds and contents of organic acids in L litters were more abundant than that in F litters.