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福建永安市杉木人工林产量及密度现状的研究 总被引:1,自引:1,他引:0
收集永安市杉木人工林基准年龄(20年)林分数据,应用气候生产潜力、密度效应指标等原理,对永安市杉木人工林产量及密度现状研究分析,提出符合永安市杉木人工林生长规律的培育措施,为杉木人工林培育获取较大经济效益提供理论参考。 相似文献
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长白落叶松工业人工林密度控制技术的研究 总被引:3,自引:0,他引:3
以马尔柯夫过程理论为基础对长白落叶松工业人工林进行了模拟密度控制,提出了合理的培育密度和相应的抚育间伐对象。结果表明:马尔柯夫过程理论确能反映长白落叶松工业人工林的直径转移过程,这对于定量分析长白落叶松工业人工林直径分布的动态规律,从而拟定合理的密度控制措施非常有益;长白落叶松工业人工林成林后的密度控制间伐无论从培育森林方面,还是从取得木材、加大林分收益方面考虑,都应该以间伐小径阶的林木为主;20-25龄长白落叶松工业人工林的经营密度以0.7为最佳。 相似文献
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本文根据我国人工林长期发展实践经验和“七五”“八五”期间针对我国人工林发展中存在问题所做的科技攻关成果进行归纳总结,为人工林的持续经营提供科技支撑。主要内容包括人工林培育上的6个方向(或目标),即定向、速生、丰产、稳定、优质和高效,以及按生态系统管理要求提出的人工林育林体系上的5个控制:遗传控制、立地控制、密度控制、植被控制和地力控制。按照上述6个方向和5个控制在人工林培育上的实施,人工林的长期生产力将会得以保持,人工林多功能培育效果也得以实现。 相似文献
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A quasi-nonlinear fracture mechanics model is presented for the analysis of row shear failure in timber connections with multiple
fasteners in a row. A prerequisite for use of the model is a known distribution on the fasteners of the total applied load.
It is shown that the ideal plastic and linear elastic fracture mechanics solutions appear as special cases of the quasi-nonlinear
model. The model offers strength predictions that include the effect of among others the number of fasteners in a row, fastener
spacing, row spacing, end-distance, edge-distance, fastener diameter, and material properties, such as shear strength, fracture
energy, and modulus of elasticity. Simple explicit expressions are obtained from the analysis for any known fastener load
distribution. For bolted connections, where bolt-hole gaps cause high loads on certain bolts at random, the model may be used
in simulation procedures or in probabilistic models. 相似文献
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珍稀树种南方红豆杉造林技术试验 总被引:1,自引:1,他引:0
通过试验研究不同造林株行距(A)、不同整地挖穴规格(B)对南方红豆杉人工造林成活率、幼林高度及地径生长量的影响差异,试验结果表明:2.0 m×2.5 m造林株行距(A)+60 cm×50 cm×40 cm整地规格(B)最好,1年生幼林平均成活率达95.6%。 相似文献
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To assess the effects of seedling spacing on one-year-old seedling morphology in the nursery, seeds of three provenances of Fraxinus angustifolia were sown at five different seedling spacings within rows of two different spacings in the seedbed. Subsequent growth performance of one-year-old seedlings was assessed by planting in the forest. Within row spacings were: 4.3, 5.0, 6.3, 8.3, and 12.5 cm, and there were five rows at 20 cm apart, or three rows at 33 cm apart across the 1.2 m wide seedbeds. Both spacings within and between rows significantly affected shoot height, root collar diameter, root dry weight and shoot dry weight, but not root/shoot ratio. Wider spacings produced larger seedlings, but only the wider spacing within rows significantly increased fine and coarse root mass. Provenances showed significant differences in diameter, root/shoot ratio, and fine and coarse roots, and they also showed interactions with row spacings in height and diameter measurements. One year after outplanting, diameter growth was significantly related to provenance, and diameter growth was 88% greater for trees from 33 cm nursery row spacing than those from 20 cm nursery row spacing. 相似文献
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以黄檗3 a生幼树为材料,对不同栽植密度的生物量进行研究,结果表明:栽植当年和翌年秋季的成活率与保存率分别为92%和91%。不同株距树高、地径生长量均达到极显著差异(P0.01),树高、地径生长量从大到小顺序依次为株距0.5 m1 m0.3 m1.5 m;而不同行距对树高、地径生长量均无影响。采用一元生物量模型计算生物量,总生物量最大的种植密度为33 300株·hm~(-2)(株行距0.3 m×1.0 m),可产生干物质3 930.06 kg·hm~(-2);最小的为3 300株·hm~(-2)(株行距1.5 m×2.0 m),干物质仅为344.08 kg·hm~(-2)。 相似文献
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采穗圃不同营建及管理技术对马占相思穗条产量的影响 总被引:1,自引:0,他引:1
通过正交试验设计研究母株不同定植株行距、不同截干高度及施用不同基肥种类对马占相思嫩枝及硬枝产穗量的影响差异。结果表明:母株以20cm×25cm定植株行距(A2)+施1 125kg/hm2硫酸钾复合肥(B2)+母株距根茎部位25cm处截干高度(C3)组合(A2B2C3)最好,对嫩枝及硬枝产穗量均最高。 相似文献
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吉林省长白山区侵蚀沟生物治理的研究 总被引:1,自引:0,他引:1
在吉林省长白山区采用生物治理侵蚀沟试验研究,结果表明:采用紫穗槐、胡枝子进行浅沟治理,防治水土流失作用明显,最佳组合为:坡度≤15°地段,紫穗槐、带间距8 m和胡枝子、带间距8 m;坡度≥15°地段,紫穗槐、带间距4 m和胡枝子、带间距4 m。采用旱柳4~8 cm粗的茎干在沟底埋桩进行深沟沟底治理,缓流挂淤作用显著,最佳组合为:横隔间距2 m,茎干间距20 cm,埋干深度50 cm,茎干长度100 cm。采用紫穗槐、胡枝子进行深沟沟坡治理,最佳组合为:紫穗槐、带状栽植(株距0.3 m、行距1.0m)和胡枝子、带状栽植(株距0.3 m、行距1.0 m)。 相似文献