ABSTRACT Many studies have focused on soil erosion in unmanaged Japanese cypress plantations because the sparse understory vegetation and litter covering the forest ground enhance soil erosion. In this study, soil erosion, litter, and overland flow measurements were conducted over 14 months to identify the spatio-temporal variation and examine the optimal sample size. Fifteen traps (each 0.25 m wide) were installed in line along the bottom of a 15-m-wide slope. Soil erosion and overland flow had large spatial variations as compared to litter. The temporal coefficient of variation of soil erosion and overland flow was highest during dry seasons, while smaller during wet seasons. The random sampling analysis showed that the rate of decrease in spatio-temporal variation became moderate as the sample size increased beyond six. This result indicated that the optimal sample size was five, the total width of which was equivalent to about 8% of the monitored slope width.

中文翻译：

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日本柏树人工林的土壤侵蚀和地表水流：时空变化和采样策略

摘要 许多研究集中在未管理的日本柏树人工林中的土壤侵蚀，因为覆盖林地的稀疏林下植被和枯枝落叶加剧了土壤侵蚀。在这项研究中，对土壤侵蚀、凋落物和地表流量进行了 14 个月的测量，以确定时空变化并检查最佳样本大小。沿着 15 米宽的斜坡底部并排安装了 15 个疏水阀（每个 0.25 米宽）。与凋落物相比，土壤侵蚀和地表水流具有较大的空间变化。土壤侵蚀和地表径流的时间变异系数在旱季最高，雨季较小。随机抽样分析表明，随着样本量增加到超过 6 个，时空变化的减少率变得适中。