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首页> 外文期刊>Scottish Forestry >Improved Sitka spruce planting stock; seedlings from a clonal seed orchard or cuttings from full-sibling families?
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Improved Sitka spruce planting stock; seedlings from a clonal seed orchard or cuttings from full-sibling families?

机译：改良的锡特卡云杉种植库存;来自克隆种子园的幼苗还是来自全兄弟家庭的插条？

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Forest managers now have a choice of improved Sitka spruce planting stock: bare-rooted seedlings grown from seed collected in a seed orchard following open pollination between selected parents, or rooted cuttings harvested from donor plants raised from seed following artificial pollination between selected parents. Seed orchards are many years in preparation before planting, and take a further 10 years from planting to yield commercial quantities of seed. Seed for rooted cutting production can be produced in the same year as the parents' combination is conceived. Despite these differences in time scale, predicted rates of growth from the two sources are roughly similar. The main differences between stands grown from the two sources are further improvements in stem straightness, branching quality, and general crop uniformity of the trees raised from the more highly selected full-sibling cuttings. To justify the higher purchase price of the cuttings stock, these improvements in quality traits must translate into additional revenue through an increase in the proportion of green logs at harvest. Using predictions of saw-log proportions estimated from felling a mature progeny trial and then extrapolated to components of the breeding population, this study is a modelling exercise to investigate the most economically appropriate source of improved Sitka spruce planting stock for a range of different growth rates, and cost and revenue variables. The model required certain standard assumptions to be made regarding cost and benefits of full-sibling cuttings and seed orchard seedling stock, which were then varied in a sensitivity analysis. The main conclusion from this modelling exercise was that planting vegetatively propagated stock (cuttings) should be made with caution in the public sector (3.5/3.0% interest rates) and with particular care in the private sector unless favourable grants are applicable (assuming 5% interest rates). There are many situations when seed orchard stock would be more appropriate. Despite predictions of an increase in final rotation value due to a greater proportion of the higher-value green logs from the full-sibling cuttings stock, once discounted to the year of planting, this extra revenue was generally not sufficient to justify planting the higher-cost cuttings. The full-sibling cuttings stock only became financial beneficial if it was assumed that (i) the premium paid to the nursery for cuttings relative to seed orchard stock was low (less than ounds>100/hectare); (ii) the premium of green logs relative to red logs at harvest was high (over ounds>10 m-3); and (iii) the trees would be expected to grow in excess of Yield Class 18 and have a rotation length of at least 40 years. Planting cuttings on sites which will be left unthinned is not recommended unless very optimistic assumptions for green-log proportions and premiums relative to red log are made.
机译：森林管理者现在可以选择改良的锡特卡云杉种植种：选择的父母之间进行开放授粉后，从种子园中收集的种子中生长的裸根苗，或者选择的父母之间进行人工授粉后，从种子中培育的供体植物中收获的生根cutting插。种子园在种植前已经准备好很多年，从种植到生产商业数量的种子还需要10年的时间。可以在设想父母的结合的同一年生产用于生根的cutting插生产的种子。尽管时间尺度存在这些差异，但两种来源的预测增长率大致相似。从这两种来源生长的林分之间的主要区别是，从更严格选择的全同胞cutting插中生长的树木的茎直度，分枝质量和总体作物均匀性得到了进一步改善。为了证明the插原料更高的购买价格，质量特性的这些改善必须通过增加收获时的原木比例来转化为额外的收入。本研究使用从成熟的后代试验中砍伐后推断出的原木比重的预测值，然后将其外推到繁殖种群的组成部分，从而进行建模研究，以研究在各种不同增长率下最经济的锡特卡云杉种植改良种资源以及费用和收入变量。该模型要求对全兄弟cutting插和种子园果苗苗木的成本和收益做出某些标准假设，然后在敏感性分析中对其进行更改。建模工作的主要结论是，除非有适当的赠款（假设为5％），否则在公共部门（无息）种植植物繁殖种群（砍伐物）应谨慎（利率为3.5 / 3.0％），在私营部门应特别谨慎。利率）。在许多情况下，种子园的种子会更合适。尽管由于全同级rotation插存量的较高价值绿色原木比例较大（一旦折现到播种年份），预计最终轮伐价值将增加，但这一额外收入通常不足以证明种植较高价格的原木是合理的。削减成本。仅在以下情况下，全姐妹s插种群才有经济利益：（i）苗圃支付给苗圃的费用相对于种子园种子种群的溢价较低（小于100英镑/公顷）; （ii）收获时绿色原木相对于红色原木的溢价很高（超过10 m-3磅）; （iii）预计这些树木的生长将超过18级的产量，并且轮伐期至少为40年。除非对绿原木比例和相对于红原木的溢价做出非常乐观的假设，否则不建议在不会稀疏的地方种植插条。

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