干旱区研究 ›› 2018, Vol. 35 ›› Issue (3): 524-531.doi: 10.13866/j.azr.2018.03.04

• 水土资源 • 上一篇    下一篇

黄土高原南北样带土壤有机碳空间变异及其影响因素

任广琦1,  贾小旭2,3, 贾玉华1,2 , 郭成久   

  1. (1.沈阳农业大学 水利学院,辽宁 沈阳 110000; 2.中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室,北京 100101; 3. 中国科学院大学资源与环境学院,北京 100190)
  • 收稿日期:2017-09-23 修回日期:2017-11-06 出版日期:2018-05-15 发布日期:2018-06-01
  • 通讯作者: 贾小旭.E-mail:jiaxx@igsnrr.ac.cn
  • 作者简介:任广琦(1993-),女,硕士研究生,主要从事土壤性质空间变异研究.E-mail:2993150328@qq.com
  • 基金资助:
    国家自然科学基金项目(41501233,41530854)资助

Spatial Variation of Soil Organic Carbon Content and Its Driving Factors along South-North transect in the Loess Plateau of China

Ren Guang-qi1, Jia Xiao-xu 2,3, Jia Yu-hua 1,2 ,Guo Cheng-jiu1   

  1. (1.GUANGQI REN Water Conservancy Institute Shenyang Agricultural Uinversity, Liaoning Shenyang, 110000; 2. Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China; 3. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China)
  • Received:2017-09-23 Revised:2017-11-06 Online:2018-05-15 Published:2018-06-01

摘要: 为阐明黄土高原土壤有机碳空间变异特征及影响因素,在南北方向布设一条长860 km具有明显环境梯度的样带,采用经典统计学和地统计学方法,分析了0~500 cm剖面土壤有机碳的空间分布规律、变异特征及其与环境因子的关系。结果表明:土壤有机碳在水平方向上由南到北逐渐降低,垂直方向上0~100 cm随土层逐渐降低,100 cm以下趋于稳定;0~500 cm不同土层土壤有机碳均呈中等程度变异,变程60~270 km;0~40 cm土壤有机碳空间分布主要受降水和坡度的影响,40 cm以下主要受土壤质地和气候的影响,表明区域尺度浅层土壤有机碳空间分布取决于气候和地形条件,深层土壤有机碳主要受土壤质地和气候共同影响。

关键词: 黄土高原, 样带, 土壤有机碳, 空间变异, 环境因子

Abstract:

 The China’s Loess Plateau is characterized by severe water shortage, thick loess deposits and intensive soil erosion, and it is a typical ecological fragile region in China and even around the world. Serious soil erosion and long-term irrational land reclamation in this region leads to a decline of soil organic carbon content (SOC). As an important component in the terrestrial ecosystem, the SOC which is closely related to soil physical, chemical and biological properties is a key factor affecting soil fertility and productivity of ecosystem. Slight fluctuation of soil organic carbon pool, which is caused by the changes of land use, land management measures or soil erosion rate, affects strongly the carbon dioxide in atmosphere and thus the global climate change. The spatial distribution of SOC has generally a high heterogeneity due to the influence of climate (i.e. temperature and precipitation), soil texture, soil type, vegetation type, terrain conditions (such as elevation, slope aspect and slope gradient) and land use type. However, the SOC was focused on mainly on the small spatial scales (generally < 2 km2) in previous studies, which is insuf?cient for understanding the spatial characteristics of SOC on regional and/or global scale. Besides, the available researches overlooked the amount and spatial pattern of SOC in deeper soil layers (deeper than 1 m), which failed to provide a reliable evidence for precise regional soil carbon stock evaluation. In this study, an 860 km south-north transect was designed, and the values of SOC at 500 cm depth were measured at an interval of 10 km (n= 86) along the transect. Thus, the objectives of the study were to investigate the spatial variation of SOC on regional scale and to derive the primary factors dominating the spatial distribution of SOC in different soil layers by using the classical statistics and geostatistics. The results showed that the mean SOC of the 0-500 cm soil profile decreased generally from the south to the north of the plateau along the horizontal direction. Along the vertical direction, SOC decreased gradually with the increase of soil depth above 100-cm soil layer, while it tended to be stable in the 100-500 cm layer. Under different land use types, SOC was generally in an order of cropland (5.79 g·kg-1) > forestland (3.34 g·kg-1) > grassland (2.20 g·kg-1). A moderate variation of SOC occurred in various soil layers along a 0-500 cm profile, and the best fitting semivariogram models for SOC in the 0-150 cm and 150-500 cm soil layers were Gaussian and Exponential. The controlling factors of SOC were different from different soil layers: SOC in the top 40 cm soil layer was mainly influenced by mean annual precipitation and slope gradient, while that in the 40-500 cm soil layer was controlled by soil texture, mean annual precipitation and temperature. Results suggested that the regional distribution of SOC in shallow soil layers (< 40 cm in depth) was determined by climate and topographic conditions, while that in deep soil layers (40-500 cm in depth) tended to be determined by soil texture and climate. The results could provide a scientific basis for ecological regeneration and regional soil carbon stock evaluation.

Key words: The Loess Plateau, Transect, Soil organic carbon, Spatial variability, Environmental factor