干旱区生态环境知识资源中心(Arid): 西藏地区土壤表层和全剖面背景有机碳库及其空间分布

Arid

	西藏地区土壤表层和全剖面背景有机碳库及其空间分布
其他题名	Background organic carbon storage of topsoil and whole profile of soils from Tibet District and their spatial distribution
	范宇; 刘世全; 张世熔; 邓良基
ISSN	1000-0933
出版年	2006
卷号	26 期号:9 页码:2834-2846
中文摘要	根据西藏2607个土壤剖面资料和1∶200万土壤图的数字化处理，按地区以制图单元土壤亚类为基础估算土壤有机碳密度（ＳＯＣＤ）和储量（ＳＯＣＲ），并探讨其空间分布特征。结果表明：(1）西藏地区的ＳＯＣＤ平均为7.48 kg m－２，并随土壤类型而变化，以山地铁铝土最高（29.2 kg m－２），其后依次是山地淋溶土（16.6 kg m－２）、高山草甸型土壤（12.2 kg m－２）、山地半淋溶土（9.2kg m－２）、高山草原型土壤（3.7kg m－２）等，而以寒冻土（1.6kg m－２）和高山荒漠土（1.3kg m－２）为最低。同时土壤表层（0～20cm）的ＳＯＣＤ平均为4.27 kg m－２，占全剖面总量的57%，反映西藏地区土壤有机碳库（SOCP）对环境变化具有较高的敏感性。(2）西藏ＳＯＣＤ具有独特的水平地带分布，即自藏东南向西北逐次降低，由此可大体分为高（Ⅰ）、中（Ⅱ）、低（Ⅲ）、极低（Ⅳ）4个碳密度带，其平均ＳＯＣＤ分别为21、10、4、＜2 kg m－２；各带ＳＯＣＤ又有不同的垂直分布，总趋势是由复杂到简单，但均以最高位置的寒冻土极低碳密度为终点。(3）西藏ＳＯＣＲ总计为8.23 Pg，占全国ＳＯＣＲ总量的9.14%。各地ＳＯＣＲ分布极不平衡：就各碳密度带的ＳＯＣＲ相对比例（占西藏全区总量%）而言，Ⅰ、Ⅱ、Ⅲ、Ⅳ带分别为25%、50%、22%、3%，其中Ⅰ、Ⅱ带合计的土壤面积仅占45%，而ＳＯＣＲ却占75%，因而是西藏SOCP的主体；而反映土壤储碳能力的丰度指数（R）则分别为2.82、1.37、0.53、0.23。就各地区的ＳＯＣＲ而言，以那曲地区最大（2.19Pg），拉萨地区最小（0.31Pg）；而R值则是林芝＞山南＞拉萨＞昌都＞日喀则＞那曲＞阿里。这些结果将为全球变化研究与区域环境评价提供有力的支撑.
英文摘要	As the main part of Qinghai-Tibet Plain, the Tibet district has a vast territory with high altitudes, cold climates and widely distributed frozen soils. Its soil organic carbon pools (SOCP) are special and important components of Chinese SOCP and could effectively affect and sensitively respond to the global climate change. Therefore, the baseline values of SOCP and their spatial distribution in Tibet are critical to a good understanding and accurate prediction of the global climate change. However, a complete and accurate SOCP database for Tibet is still to be determined. In this study, the baseline values of soil organic carbon density (ＳＯＣＤ) and reserve (ＳＯＣＲ) were determined for the entire Tibetan region and the ＳＯＣＤ geographic distribution maps were drawn using organic carbon data from 2607 soil profiles and the digitized 1∶2,000,000 Tibetan soil map, both obtained from the soil survey in Tibetan Autonomous Region. The spatial distribution of ＳＯＣＤ and ＳＯＣＲ values was determined using the digitized ＳＯＣＤ geographic distribution map. In estimation of ＳＯＣＤ and ＳＯＣＲ, the international soil classification system was adopted. In consideration of the large regional variation in SOCP, soil profile data (thickness of soil layers, organic matter content, bulk density, gravel content as well as soil profile geographical　location, elevation, vegetation cover and so on) were collected by soil subgroups, the charting units in soil maps. The corresponding soil profile database was also established. In recognition of the fact that the degree of weathering is low and gravel content high for all Tibetan soils, the soil organic carbon content for each soil layer was corrected for its gravel content in ＳＯＣＤ estimation and the ＳＯＣＤ of the whole soil profile was the summation of the individual soil layers in each profile. The ＳＯＣＤ of each region or each soil type was a weighted average based on actual soil acres which is also the basis for estimating ＳＯＣＲ. Finally, soil organic carbon richness rate index (R) was calculated to evaluate the storage capacity of organic carbon by various soil types and in different regions. The major findings were summarized as follows: (1)The ＳＯＣＤ of the whole soil profile varied from 0.48 kg m－２ to 50.71 kg m－２ with an average of 7.48kg m－２, less than the average value for China (8.0-10.5 kg m－２), and much lower than that of the world (12.1kg m－２). Therefore, Tibet is one of region in China with the lowest soil organic carbon density. (2)The ＳＯＣＤ values for different soil types varied substantially. For examples, the ＳＯＣＤ values follow the order: Ferro-allitic soils（29.2 kg m－２）> Eluvial soils（16.6 kg m－２）> Alpine meadow soils（12.2 kg m－２）> Semi-eluvial soils（9.2 kg m－２）> Alpine steppe soils（3.7 kg m－２）> Frigid frozen soils（1.6 kg m－２）and Alpine desert soils (1.3 kg m－２). (3) The ＳＯＣＤ of surface soil layers (0～20cm) varied from 0.05 kg m－２ to 26.0 kg m－－２ with an average of 4.27 kg m－２, accounting for 57% of the average ＳＯＣＤ for the whole soil profiles. This percentage is obviously higher than the corresponding average value in China (<=48%), implying that the Tibetan soil organic carbon pools have a high instability and might be more sensitive to the global climate change. (4)The ＳＯＣD values of Tibetan soils had a unique horizontal regional distribution pattern; it decreased gradually from the southeast to the northwest Tibet. The soils can be divided into four zones according to their ＳＯＣD values: high (Ⅰ), medium (Ⅱ), low (Ⅲ), and extremely low (Ⅳ), corresponding to average ＳＯＣＤ values of 21 kg m－２, 10 kg m－２, 4 kg m－２ and ＜2 kg m－２, respectively. Within each carbon density zone, there is also a unique vertical distribution pattern. Firstly, soil organic carbon density was higher at low altitude and decreased as the altitude increased. Secondly, the end zone of various vertical patterns was always the extremely low carbon density zone (alpine frost soils) at the highest altitude. (5)Total ＳＯＣＲ for Tibet is 822.76107t (8.23Pg), about 9.14% of the national value (about 90 Pg); Of that, the ＳＯＣＲ of soil surface layers (0-20cm) in Tibet is 469.08107t (4.69Pg). The spatial distribution of ＳＯＣＲ values in Tibet is extremely imbalanced, which is not only related to the large variation of ＳＯＣＤ values in various soil types, but also due to the non-uniform distribution of soil types. Firstly, the four kinds of soils with the highest ＳＯＣＲ values, namely Felty soils, Frigid Calcic soils, Dark felty soils and Dark-Brown Earths, account for 24%, 22%, 15% and 9% of total ＳＯＣＲ in Tibet, respectively, or altogether for 70% of total ＳＯＣＲ in Tibet. Therefore, they are major types of soils as far as SOCP is concerned. Next, the ＳＯＣＲ values for ＳＯＣＤ zones Ⅰ, Ⅱ, Ⅲ, Ⅳ accounted for 25%, 50%, 22%, and 3% of the total ＳＯＣＲ for Tibet, respectively. The richness index (R) which reflects the capacity of soil to store carbon was 2.82, 1.37, 0.53, 0.23 for zone Ⅰ, Ⅱ, Ⅲ, Ⅳ, respectively, totally consistent with the change in the ＳＯＣＤ values. Although the area of the Zone I and Ⅱ　was only for 45% of the total soil acres, the ＳＯＣＲ accounted for 75% of that in Tibet. Therefore, Zone I and Ⅱ are the major reservoir of the SOCP in Tibet. With respect to ＳＯＣＲ of various regions, Naqu is the greatest, while Lhasa is the smallest one. In terms of carbon storage capacity, the order is: Linzhi> Shannan> Lhasa> Qamdo> Zigaze> Naqu> Ali, which is mainly determined by R of predominant soil types in each region. The results will effectively support the research of global change and the work of regional environmental assessment.
中文关键词	西藏 ; 土壤有机碳密度（ＳＯＣＤ） ; 土壤有机碳储量（ＳＯＣＲ） ; 空间分布
英文关键词	tibet soil organic carbon density (ＳＯＣＤ) soil organic carbon reserve (ＳＯＣＲ) spatial distribution
语种	中文
国家	中国
收录类别	CSCD
WOS类目	ECOLOGY
WOS研究方向	Environmental Sciences & Ecology
CSCD记录号	CSCD:2442965
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/220045
作者单位	四川农业大学资源环境学院, 雅安, 四川 625014, 中国
推荐引用方式 GB/T 7714	范宇,刘世全,张世熔,等. 西藏地区土壤表层和全剖面背景有机碳库及其空间分布[J],2006,26(9):2834-2846.
APA	范宇,刘世全,张世熔,&邓良基.(2006).西藏地区土壤表层和全剖面背景有机碳库及其空间分布.,26(9),2834-2846.
MLA	范宇,et al."西藏地区土壤表层和全剖面背景有机碳库及其空间分布".26.9(2006):2834-2846.