Controlling the long-term effect of management on the quantity and properties of individual boards is a fundamental challenge for silviculture. Within this basic study on Douglas-fir, we have investigated the sensitivity of the net present value (NPV) to three most common planting densities and a prominent pruning strategy. We therefore have applied an individual tree growth model, which represents intrinsic stem structure as a result of crown competition. The model extrapolated board strength development to the rotational age of 70 years, starting from real and comprehensive data recorded from experimental Douglas-fir plots at the age of 20 years. Total volume production increased from about 1600 m 3 ha −1 for 1000 and 2000 trees ha −1 to 1800 m 3 ha −1 for 4000 trees ha −1 . The economic superiority of the lowest density stands increased considering the NPV at inflation-adjusted interest rates of 0%, 2% and 4%: Given an interest rate of 2% and no pruning, the NPV at 2000 was at about 50% of the one at 1000 trees ha −1 . The NPV at 4000 trees ha −1 was even negative. Generally, artificial pruning was not effective. The revealed financial trade-off between growth and timber quality in young stands underlines the importance of silvicultural guidelines, which quantify the effect of management on yield per strength class and financial outcome.

中文翻译：

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间距和修剪对花旗松锯材数量、质量和经济性的影响：情景和敏感性分析

控制管理对单个板的数量和特性的长期影响是造林的一项基本挑战。在这项关于花旗松的基础研究中，我们调查了净现值 (NPV) 对三种最常见的种植密度和一种突出的修剪策略的敏感性。因此，我们应用了一个单独的树木生长模型，它代表了树冠竞争的内在茎结构。该模型从 20 岁时实验花旗松地块记录的真实综合数据开始，将板强度发展外推到 70 岁轮换年龄。总产量从 1000 和 2000 棵树 ha -1 的约 1600 m 3 ha -1 增加到 4000 棵树 ha -1 的 1800 m 3 ha -1 。考虑到通货膨胀调整后利率为 0%、2% 和 4% 的 NPV，最低密度的经济优势增加了：假设利率为 2% 且没有修剪，2000 年的 NPV 约为一棵在 1000 棵树 ha -1 。4000 棵树 ha -1 的 NPV 甚至为负。一般来说，人工修剪是无效的。幼林生长和木材质量之间显示的财务权衡强调了造林指南的重要性，该指南量化了管理对每个强度等级的产量和财务结果的影响。