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| Estimating Soil Organic Carbon Density at Different Slope Positions in a Typical Karst Peak-cluster Depression Area by Ground Penetrating Radar Technology |
| Received:November 10, 2014 |
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| KeyWord:Karst peak-cluster depression area;ground penetrating radar;soil distribution;soil organic carbon density |
| Author Name | Affiliation | E-mail | | XIA Yin-hang | The Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
University of Chinese Academy of Sciences, Beijing 100049, China
Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang 547100, China | | | LI Lei | The Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
University of Chinese Academy of Sciences, Beijing 100049, China
Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang 547100, China | | | CHEN Xiang-bi | The Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang 547100, China | | | HE Xun-yang | The Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang 547100, China | | | LIU Kun-ping | Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang 547100, China | | | WU Jin-shui | The Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China | | | SU Yi-rong | The Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang 547100, China | yrsu@isa.ac.cn |
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| Abstract: |
| High proportion of bare rocks, disconnected soil distribution and large variation of soil depths are the characteristics of Karst landforms, leading to hardly accurate estimation of soil organic carbon density(SOCD) by the conventional methods. In this study, four quadrats were selected at each of different slope positions(upper-slope, mid-slope, lower-slope and depression) in a typical Karst peak-cluster depression area. Soil depth and soil distribution in each quadrat were measured by ground penetrating radar(GPR) technology, and soil volume fraction was then calculated. Soil profile samples were collected from each quadrat and analyzed for soil organic matter, gravel content and bulk density. The SOCD was then calculated according to soil organic carbon(SOC) content, gravel content, bulk density and soil volume fraction. Results showed that soil depths were between 0~30 cm at upper-slope, mid-slope and lower-slope, with soil volumetric fractions ranging from 72%±16% to 78%±6%; while soil depth was up to 70 cm, with soil volumetric fractions of 64%±17% in depression area. The SOC content decreased significantly from 0 to 30 cm(P<0.05) within a soil profile, but it gradually increased from the depression area to the upper-slope, showing a special phenomenon of “nutrient inversion” in the Karst areas. The SOCD in 0~20 cm depth gradually reduced from the upper~slope to the depression positions, and showed significant difference between the upper-slope and depression positions(P<0.05). However, the SOCD in 0~100 cm profile in the depression position was significantly higher than that in the slope positions(P<0.05). Compared to the “Average Depth” method, the GPR method had relative error of 0.3%~14.5%, showing no significant difference. Therefore, GPR method could be used to accurately detect soil depth and soil distribution for estimating SOCD in disconnected soils in Karst area, and is a reliable method to estimate SOC storage in Karst areas with a promising accuracy. |
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