Douglas-fir (Pseudotsuga menziesiivar. menziesii (Mirbel) Franco) plantation forests of the coastal Pacific Northwest have been intensively managed to improve the yield of forest products. However, the long-term effects of these management techniques have received limited research attention in this region. Three affiliate Long-Term Soil Productivity study sites were installed in Douglas-fir forests to understand the impacts of organic matter removals and vegetation control on soil productivity over time. Matlock and Fall River are located in Washington, USA and Molalla is located in Oregon. Organic matter removal treatments included traditional bole-only harvest (BO), whole tree removals (WT), and a whole tree plus coarse woody debris removal (WT+) (Fall River only). Five years of annual vegetation control (AVC) was compared with a conventional initial vegetation control (IVC) treatment at all sites. Douglas-fir biomass allocation to foliage, branch, and stem components was modeled using 15- to 20-year-old trees from this study along with 5- to 47-year-old trees from previous studies on these sites. Across all sites, model predictions indicated that the WT treatment had 7.1 to 9.7 Mg ha⁻¹ less Douglas-fir biomass than the BO treatment. There was 1.5 to 20.5 Mg ha⁻¹ greater Douglas-fir biomass in the AVC treatment than in the IVC treatment at all sites. Douglas-fir carbon and nitrogen biomass were consistently lower in the WT treatment, but there were no significant changes in overall site nutrient pools. The AVC treatment resulted in greater Douglas-fir nutrient pools yet there was a net loss in site calcium, magnesium, and potassium due to lower forest floor and soil base cation pools. While WT removals did not significantly affect site nutrition, the decrease in Douglas-fir biomass at all sites and increase in invasive Scotch broom (Cytisus scoparius (L.) Link) biomass at Matlock suggests that the standard practice of retaining harvest residuals is beneficial. The use of intensive vegetation control to improve Douglas-fir biomass and nutrition must be balanced with retaining soil base cations.

中文翻译：

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去除有机物和植被后15–20年的道格拉斯冷杉生物量分配和净养分池

道格拉斯冷杉（Pseudotsuga menziesii var.menziesii（Mirbel）Franco）西北太平洋沿海地区的人工林得到了密集管理，以提高林产品的产量。但是，这些管理技术的长期效果在该地区仅受到了有限的研究关注。在道格拉斯冷杉森林中安装了三个附属的长期土壤生产力研究站点，以了解有机物去除和植被控制随时间推移对土壤生产力的影响。Matlock和Fall River位于美国华盛顿，Molalla位于俄勒冈州。有机物去除处理包括传统的纯树丛收获（BO），整棵树（WT）和整棵树以及粗木屑去除（WT +）（仅落河）。在所有地点将五年的年度植被控制（AVC）与常规初始植被控制（IVC）处理进行了比较。道格拉斯冷杉生物量分配到枝叶，树枝和茎的成分是使用本研究中的15至20年龄树木以及这些地点先前研究中的5至47年龄树木建模的。在所有站点上，模型预测表明WT处理的面积为7.1至9.7 Mg ha道格拉斯杉生物量比BO处理少^-1。在所有地点，AVC处理的花旗松生物量比IVC处理高1.5至20.5 Mg ha ^-1。道格拉斯冷杉的碳和氮生物量在WT处理中始终较低，但总部位养分池没有显着变化。AVC处理导致花旗松的养分池更大，但由于林地和土壤基础阳离子池的减少，导致钙，镁和钾的净损失。虽然去除野生型不会显着影响部位营养，但所有部位道格拉斯冷杉生物量的减少和侵入式苏格兰扫帚（Cytisus scoparius）的增加（L.）Link）马特洛克的生物质表明，保留收获残余物的标准做法是有益的。强化植被控制以提高花旗松生物量和营养水平必须与保留土壤基础阳离子保持平衡。