ABSTRACT In drained forest sites, ditch cleaning (DC) may be needed to restore the drainage function of ditches and maintain favourable growing conditions. The main aims of this study were (i) to estimate the growth responses of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst) stands following DC, and (ii) to test the hypothesis that stand stocking should be less than 150 m3 ha−1 at DC to obtain a growth response. This survey included 14 ditched stands in Sweden on both mineral and peat soils. The methodology was based on evaluating growth rates before and after the DC operation (growth ratio), reconstructing the growth by taking increment cores from the tree trunks. The measured growth was related to growth derived using a growth simulator as if DC had not been conducted. The results showed an average growth increase of 1.6 m3 ha−1 yr−1 for about 25 years after DC in the stands containing 50–200 m3 ha−1. The growth response appeared to be positively related to stand age, trees ha−1 and site index, and negatively related to stand volume, supporting the hypothesis that stand stocking is an important factor to consider when assessing the need for DC.

中文翻译：

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沟渠清理后樟子松和冷杉的生长反应——瑞典的一项调查

摘要 在排水林地，可能需要清沟 (DC) 以恢复沟渠的排水功能并保持有利的生长条件。本研究的主要目的是 (i) 估计苏格兰松 (Pinus sylvestris L.) 和挪威云杉 (Picea abies L. Karst) 在 DC 之后的生长响应，以及 (ii) 检验立木放养应该在 DC 时小于 150 m3 ha-1 以获得生长响应。该调查包括瑞典的 14 个在矿物和泥炭土壤上的沟渠。该方法基于评估 DC 操作前后的生长率（生长率），通过从树干中提取增量核心来重建生长。测量的生长与使用生长模拟器得出的生长相关，就好像没有进行 DC 一样。结果显示平均增长率为1。6 m3 ha-1 yr-1 在 DC 后约 25 年，在包含 50-200 m3 ha-1 的林分中。生长响应似乎与林分年龄、树木 ha-1 和立地指数呈正相关，与林分数量呈负相关，支持在评估 DC 需求时林分放养是要考虑的重要因素的假设。