The aim of this study is to investigate the spatial distribution of soil organic C stock and to determine the optimal number of samples required for its determination, in a small karst basin. By taking the soil organic C stock in the Houzhai River Basin, calculated on the basis of a 150 by 150 m grid sampling design as original data and selecting sample sets at five grid scales (300, 450, 600, 750, and 900 m), the optimal number of samples for different sampling distances was obtained, using geographic information system (GIS) technology and geostatistical analyses. With increasing sampling distance, the coefficient of variation of the soil organic C stocks first increased and then decreased; the spatial predictions of the soil organic C stock tended to be smoother, and the ability to represent detail was weaker. The prediction accuracy was comprehensively discussed. When the surface soil organic C stock (0–20 cm) was considered, 357 sampling points at a sampling distance of 450 by 450 m could accurately represent its spatial variability. For a depth of 0–100 cm, 200 sampling points and a sampling distance of 600 m could accurately represent the spatial variability in the soil organic C stock. The results of this study could provide data for future studies for the estimation of soil organic C stock in the karst areas of Southwest China and similar areas.

中文翻译：

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探索最佳采样密度以表征喀斯特地区土壤碳储量的空间异质性

这项研究的目的是调查一个小型喀斯特盆地中土壤有机碳储量的空间分布，并确定确定其所需的最佳样本数量。通过以150 x 150 m网格采样设计为基础计算的后寨河流域土壤有机碳储量，并选择5个网格尺度（300、450、600、750和900 m）的样本集，使用地理信息系统（GIS）技术和地统计分析获得了不同采样距离下的最佳样本数。随着采样距离的增加，土壤有机碳库的变异系数先增大后减小。土壤有机碳储量的空间预测趋于平稳，表示细节的能力较弱。对预测精度进行了全面讨论。当考虑表层土壤有机碳储量（0–20 cm）时，在450 x 450 m的采样距离处的357个采样点可以准确地表示其空间变异性。对于0–100 cm的深度，200个采样点和600 m的采样距离可以准确地表示土壤有机碳库的空间变异性。本研究结果可为西南地区喀斯特地区及类似地区土壤有机碳库的估算提供数据。200个采样点和600 m的采样距离可以准确地表示土壤有机碳库的空间变异性。本研究结果可为西南地区喀斯特地区及类似地区土壤有机碳库的估算提供数据。200个采样点和600 m的采样距离可以准确地表示土壤有机碳库的空间变异性。本研究结果可为西南地区喀斯特地区及类似地区土壤有机碳库的估算提供数据。