不同林分土壤有机碳密度研究

Study on soil organic carbon density of different forest types

在全球气候变化背景下,森林土壤有机碳作为土壤碳库的重要组成部分,已成为森林生态系统碳循环研究的重点之一;而森林土壤有机碳在剖面上具有明显的垂直分布差异,根据土壤发生层次特点,分别研究各层土壤有机碳含量分布规律,对于准确确定森林土壤碳储量具有重要意义。2008年7月在北京西山妙峰山林区侧柏(Platycladus orientalis)林、刺槐(Robinia pseudoacacia)林、栓皮栎(Quercus variabilis)林和侧柏、油松(Pinus tabulaeformis)混交林内,分别随机选取3个位置挖土壤剖面,然后根据土壤发生层次性特点,把各剖面划分为四个土层(0～10 cm,10～20 cm,20～40 cm和40～60 cm),每层用环刀取样测定土壤容重,用土壤袋采集1 000 g的土壤样品,经除杂、风干、过筛等程序后,对土样的有机碳含量和碳密度进行了测定和初步研究。结果表明:4种林分下土壤有机碳平均含量和土壤有机碳密度不同,不同林分土壤0～10 cm有机碳含量和碳密度最高,并且均随土壤深度增加呈降低的趋势;其土壤有机碳密度的大小顺序为:栓皮栎林>侧柏、油松林>侧柏林>刺槐林。4种林分类型0～20 cm土层单位面积有机碳储量占总有机碳储量分别为:栓皮栎林51.1%,刺槐林44.2%,侧柏林43.0%,侧柏、油松混交林37.7%,平均为44.0%。

In the context of global climate change,as a component of soil carbon pool the forest soil organic carbon（SOC） has become one of the important issues in the study of forest ecosystem carbon cycle;moreover,forest SOC differed significantly in soil profile and research of content of SOC in various soil layers according to the process of soil genesis has great significance for accurate determination of forest soil carbon storage.In July 2008,3 soil profiles were selected under four forest types（Platycladus orientalis forest,Robinia pseudoacacia forest,Quercus variabilis forest and Mixed forest of Pinus tabulaeformis and Platycladus orientalis,） in miaofengshan forest farm of Beijing,and each profile was divided into 4 soil layers（0-10 cm,10-20 cm,20-40 cm and 40-60 cm） to measure soil bulk density with soil ring sampler and to collect 1 000-gram soil sample using cloth-bag,for measuring of SOC content and calculating of SOC density,after purification,air drying and sifting.The results showed that the different SOC content and its density under four forest types decreased with the soil depth and the highest values appear in the soil surface layer（0～10 cm）.The order of its SOC density was Quercus variabilis forest 〉Mixed forest of Pinus tabulaeformis and Platycladus orientalis〉Platycladus orientalis forest Robinia pseudoacacia forest.For unit area of the 4 forest types,the percentage of SOC storage in the top-20 cm layer were as follows： 51.1% in quercus variabilis forest,44.2% in Robinia pseudoacacia forest,43.0% in Platycladus orientalis forest,37.7% in Mixed forest of Pinus tabulaeformis and Platycladus orientalis,and the average was 44.0%.