西藏色季拉山两种典型天然林分土壤活性有机碳组分与土壤呼吸特征研究

森林土壤活性有机碳和土壤呼吸及其组分区异是森林土壤碳循环过程研究的关键问题.青藏高原亚高山原始森林植被是我国重要的生态屏障,对全球陆地生态系统的碳收支平衡具有举足轻重的作用.本研究选取西藏色季拉山两种最典型的天然林分(急尖长苞冷杉和林芝云杉)为研究对象,测定了这两种林分的土壤活性有机碳含量和同期的土壤呼吸速率及其组分速率,分析了土壤呼吸及其组分与土壤活性有机碳组分之间的关系,结果表明,西藏色季拉山两种天然林分土壤总有机碳(TOC)、土壤颗粒有机碳(POC)、易氧化有机碳(LOC)和微生物量碳(MBC)含量均具有显著的表聚性.急尖长苞冷杉林土壤活性有机碳含量较高,其TOC、POC、LOC、MBC含量分别为57.05 g·kg-1、17.9 g·kg-1、12.2 g·kg-1和365.6 mg·kg-1.两种林分的土壤总呼吸速率(Rt)和微生物呼吸速率(Rh)差异不显著(p0.05),但它们与枯枝落叶呼吸速率(Rl)和根系呼吸速率(Rr)差异极显著(p0.01),同时,Rl和Rr之间差异极显著(p0.01).从不同林分来看,林芝云杉林的土壤总呼吸速率(Rt)和微生物呼吸速率(Rh)高,而急尖长苞冷杉林的枯枝落叶呼吸速率(Rl)和根系呼吸速率(Rr)高.两种林分土壤呼吸各组分对土壤总呼吸速率(Rt)的贡献率大小依次为:RhRlRr.两种林分均表现为微生物呼吸对总呼吸的贡献比例最高,林芝云杉为92.42%,冷杉为70.81%.两种林分的土壤活性碳组分与土壤呼吸关系最密切的是MBC,其次是LOC,最不密切的是POC.

Analysis of the active organic carbon components and soil respiration characteristics from two typical natural forests in Sygara mountains, Tibet, China

Soil active organic carbon and soil respiration and its components is the key problem in forest soil carbon cycle process. The virgin forest in Tibetan Plateau is an important ecological barrier of China, which plays a decisive role in global terrestrial ecosystem carbon balance. In this study, the two most typical natural forests in Segara Mountain (Abies georgei var. smithii and Picea likiangensis var. linzhiensis) were selected as the objects, the content of active organic soil carbon and the corresponding soil respiration of these forests were measured, and the relationship between the active organic soil carbon components and soil respiration was analyzed as well. The results showed that:1The content of TOC, POC, ROC and MBC of these two forests showed significant surface accumulation. The content of active organic carbon of Abies georgei var. smithii was higher, contents of its TOC, POC, ROC and MBC were 57.05 g·kg^-1, 17.9 g·kg^-1, 12.2 g·kg^-1 and 365.6 mg·kg^-1, respectively. 2R_t and R_h between these two forests did not present significant differences (p>0.05), but significant differences were presented in R_l and R_r (p<0.01). At the same time, significant difference was presented between R_l and R_r (p<0.01). Based on the results of the two different forests, Picea likiangensis var. linzhiensis showed higher R_t and R_h, whereas Abies georgei var. smithii showed higher R_l and R_r. The descending order of the contribution rate of the soil respiration components was: R_h> R_l> R_r. The contribution rates of R_h to R_t of these two forests were the highest (92.42% in Picea likiangensis var. linzhiensis and 70.81% in Abies georgei var. smithii).3The closest relationship between active organic soil carbon and soil respiration was found for MBC, and followed by ROC and POC.