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首页> 外文期刊>Forest Ecology and Management >Tree breeding and silviculture: Douglas-fir volume gains with minimal wood quality loss under variable planting densities
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Tree breeding and silviculture: Douglas-fir volume gains with minimal wood quality loss under variable planting densities

机译：树木繁殖和造林：Douglas-FiR卷在可变种植密度下的木材质量损失最小

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Validating performance of genetically-selected trees under realistic planting scenarios is essential for confidence in tree breeding programs. Quantifying the relative impact of genetic selection and initial planting density on tree size and quality can further guide operational forest practices. We evaluate volume gains, survival, stem quality and wood quality traits on 20-year old trees representing three levels of genetic selection that were grown under four initial planting densities. Working in a realized gain trial for coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) on five replicated sites, we ask: (1) Do predicted stand productivity levels materialize as expected under different planting densities? (2) Are single-tree plot designs, simulating progeny trials, capable of producing reliable results relative to large-block designs, simulating realistic planting scenarios? (3) If trees selected for volume gain show declines in wood and stem quality relative to wild-stand controls, can this be effectively managed by altering stocking densities? Because young progeny trials are used to estimate genetic gain in tree volume at a rotation age of 60, we use a growth and yield model calibrated to wildstand controls to assess whether genetically-selected families meet projections at age 20. On average, observed stand volumes exceeded projections on four out of five sites, and in three out of four initial planting densities. At the level of site by planting density, the moderate genetic-gain population (mid-gain) exceeded projections 13 out of 20 times while the top genetic-gain population (top-crosses) exceeded projections 11 out of 20 times. This fits expectations for breeding values, which are designed to reflect general performance averaged across all environments. Using a different validation approach, large-block designs showed better performance relative to simulated progeny trial designs. Very high planting densities (1890 + stems/ha) may minimize wood quality losses of genetically-selected planting stock but effects are relatively minor, while good performance among all traits was observed at operational planting densities (similar to 1189 stems/ha). Wood density and microfibril angle proxy measures in top-crosses showed relatively minor and non-significant losses (- 1.1 to - 4.0%) compared to major and significant gains in volume per hectare at age 20 (29.0%) when averaging values at 1189 and 1890 stems/ha. Altogether, the genetic selection systems produce reliable results across a range of site qualities.
机译：在现实种植场景下验证转基因树木的性能对于树木繁殖计划的信心至关重要。量化遗传选择和初始种植密度对树尺寸和质量的相对影响，可以进一步指导操作森林实践。我们在20岁的树木上评估了代表三个遗传选择的20岁树木的体积增益，生存，茎质量和木材品质性状，这些树在四个初始种植密度下种植的三种遗传选择。在沿海道格拉斯 - 冷杉的实现增益审判（Pseudotsuga menziesii var。Menziesii（MiRB。）Franco）在五个复制的网站上，我们问：（1）预测的立场生产力水平在不同种植密度下预期实现吗？ （2）是单树绘图设计，模拟后代试验，能够产生相对于大型设计的可靠结果，模拟现实种植场景吗？ （3）如果选择用于体积增益的树木显示木材和阀杆质量相对于野生实体控制，这可以通过改变库存密度有效管理吗？由于幼年后试验用于在60岁的旋转年龄估计树木体积中的遗传增益，因此我们使用校准的生长和产量模型，以评估转基因的家庭是否在20岁时满足预测。平均而言，观察到的股票超过五个地点四个出现的预测，并在四个初始种植密度中的三个中。在现场水平通过种植密度，中等遗传增益群体（中间增益）超过20次的预测，而顶部遗传增益群（顶交字数）超过20次。这适合对繁殖值的预期，旨在反映所有环境的一般性能。使用不同的验证方法，大块设计相对于模拟后代试验设计表现出更好的性能。非常高的种植密度（1890 +茎/公顷）可能会最大限度地减少基因选择的种植库存的木材质量损失，但效果是相对较小的，而在操作种植密度下观察到所有特征的良好性能（类似于1189茎/公顷）。与1189年龄在20（29.0％）时，顶十字的木质密度和微纤维角度措施（ - 1.1至-4.0％）显示相对较小的损失（-1.1至-4.0％）（29.0％）。 1890年茎/公顷。完全，遗传选择系统在一系列场地品质上产生可靠的结果。

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