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对加快我区林木良种推广使用的认识 总被引:2,自引:0,他引:2
我区自1984年开始,与林业部联营建设五处林木良种基地,经11年建设,共完成林木良种生产面积432.79公顷,其中种子园165.87公顷,母树林337公顷,来穗围18.7公顷,良繁圃40.7公顷,每年可产良种44吨,良种橡条1120万根,良种苗木5.5万株,已形成一定的规模,良种推广使用有了长足的发展,有的良种苗木实现了良种良价,但发展不平衡,如用材林、防护林良种基地、良种壮苗都有积压现象,吉木萨尔林木良种试验站,因1988年至1990年间的杨树良种苗木大量积压,二期工程建设期间(1992年至1995年)连续四年没有按计划完成杨树良繁任务,199… 相似文献
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林木良种推广中几个问题的解决 总被引:1,自引:0,他引:1
在林木良种的推广应用上存在的忽视林木良种知识的宣传、良种价不优、良种良繁没有良法等问题,如何解决.请看下文。吉木萨尔林木良种试验站自70年代开始建设,至今已有20多年的历史,目前,该基地已成为我区最主要的白构、大叶换良种采种基地,榆树、杨树、胡杨等优良良种繁育基地,为良种繁育和提供优良壮苗做出了积极贡献。但是,在林木良种的推广应用上也存在着急待解决的问题,笔者在此提出来供探讨。一、忽视林*良种知识的宣传林木良种和农作物良种相比较具有不易体现性和显效周期长的特点.农作物生长周期一般为一年,良种的增产效… 相似文献
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洋口国有林场杉木良种基地建设效益分析 总被引:3,自引:0,他引:3
福建省洋1:7国有林场经过40多年的良种选育和良种基地建设,现拥有杉木良种基地面积335hm^2。对杉木良种基地进行投入产出比较显示,基地经济产出较培育用材林减少1638.15元/hm^2年,但社会效益显著。该场向社会提供建园技术和穗条、推广杉木良种,累计已产生社会效益10亿元以上。建议从国家层面建立林木良种繁育补贴制度,给予良种基地持续建设的资金补助,形成扶持良种基地建设的长效机制。 相似文献
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银杏良种具有时效性、地域性与相对性。针对目前银杏良种选育与推广工作中存在的问题,即良种概念模糊、良种选育缺乏严格的程序和相应的操作规程、良种退化日趋显现,提出了相应对策,如良种良法因种栽培、实行良种生产专业化、建立健全良种审定的权威机构、制定银杏良种标准等。 相似文献
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为了解杉木第3代良种的改良效果,2015年在福建省泰宁国有林场营建了杉木第3代良种改良效果测试林。造林6a后,品种间、品种内单株间生长差异结果表明:第3代良种平均树高为6.73 m,比第2代良种高9.97%;平均胸径为10.94 cm,比第2代良种大28.86%;平均单株立木材积为0.03782 m3,比第2代良种大70.59%。且第3代良种林分单株间生长分化较第2代良种林分小,林相更整齐。因此,泰宁产区可利用杉木第3代良种营造速生丰产林。 相似文献
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近日,国家林业局公布了第二批95处国家重点林林良种基地,通辽市林业科学研究所试验场被确定为国家杨树良种基地。通辽市林业科学研究所试验场始建于1972年,经营面积1600亩,良种繁育面积1200亩,在林木良种选育、引种、良种扩繁及杨树种苗研发、繁育、推广方面已有30多年的历史。 相似文献
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林木良种繁育是实现良种造林的前提,而良种造林又是提高森林的经济、生态和社会效益的物质基础。搞好林木良种繁育工作,对振兴林业,实业林业现代化,具有极其重要的战略意义,章从发展现状,有利条件,存在问题等几方面,就辽宁省形展林木良种繁育工作,进行了较为客观的综合论述,最后提出了发展策略:(1)加速树木遗传改良,推行优质种植材料造林;(2)加快良种基地建设进度,提高建设质量;(3)加强良种管理,壮大技术 相似文献
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柞木林内不同高度小气候因子时空分布规律的研究 总被引:2,自引:0,他引:2
对柞木林内不同高度的空气温度、相对湿度、绝对湿度和蒸发量进行了日、季节变化规律的研究 ,结果表明 :不同高度气温的日变化为单峰曲线 ,1d内 ,温度随树木高度的降低而减少 ;不同高度气温的季节变化总趋势是一致的 ,在 7月第五候达到最大值 ;不同高度相对湿度日变化是一致的 ,但林内相对湿度有 4种垂直分布型 ;各层次相对湿度季节变化为双峰曲线 ;所有层次绝对湿度日变化为白天高 ,夜晚低 ;日、季节各层次垂直变化不显著 ;不同高度蒸发量具有基本一致的季节变化 ,但达到峰值的时间不一致。 相似文献
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林芝地区光核桃种群的年龄结构 总被引:3,自引:0,他引:3
根据西藏林芝地区光核桃种群分布区内所选的几个代表性地点定位观测资料,通过DPS统计软件,统计出光核桃年龄与基径的回归方程,结果表明:村庄光核桃种群年龄与基径的回归方程为y=3.153 8e0.1673x,平均年龄为72.14 a;农田光核桃种群年龄与基径的回归方程为y=1.460 9x 2.750 6,平均年龄为59.15 a;村庄光核桃种群年龄与基径的回归方程为y=28.89e0.020 5x,平均年龄为68.21 a.村庄和农田型光核桃种群都处于衰退阶段,荒地光核桃种群处于从稳定型向衰退型过渡的阶段.整个林芝地区光核桃种群处于衰退状态,在所有样地调查中没有发现树龄小于10 a的植株,主要原因是人为干扰.针对这种状况,提出了3项资源保护措施:人工育种、合理开发光核桃果实资源、对光核桃的生理学和嫁接技术进行研究. 相似文献
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Wood and wood composites have viscoelasticity, and show a hysteresis loop in the stress-strain relationship during cyclic
loading such that part of the mechanical work applied is dissipated in the materials. In this study, the energy dissipation
performance of plywood specimens under cyclic shear through thickness was investigated. Fatigue testing was conducted under
three loading conditions: a square waveform at a loading frequency of 0.5 Hz, a triangular waveform at 0.5 Hz, and a triangular
waveform at 5.0 Hz. The stress level was determined to be 0.5, 0.7, and 0.9 of the static strength in shear through thickness.
The energy dissipation ratio was defined as the ratio of energy loss per cycle to the strain energy per cycle, and was evaluated
throughout the fatigue test. It was found that the energy dissipation ratio of a plywood specimen was kept constant during
most of the fatigue process for a given stress level and loading condition. The energy dissipation performance was significantly
dependent on stress level and loading condition, and became higher according to the damage intensity of cyclic load even if
the same strain energy was applied. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(6):496-504
The effect of the timing of precommercial thinning on the productivity of work was examined in young Norway spruce [Picea abies (L.) Karst.] stands in southern Finland. The common problem of large variation between sample plots in time studies was avoided by introducing a new approach based on a combination of stand measurements, tree-ring analysis and existing work productivity functions. The results indicated that a 2 year delay in the precommercial thinning of a stand was enough to cause an increase of 10-42% in the consumption of working time at a mean height of 1.5-3.1 m. At a later thinning, at a mean height 4.1-7.2 m, the increase was 8-24%. The development of the stand up to the first commercial thinning was not significantly influenced by a 2 year delay in the late precommercial thinning. 相似文献
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根据5a定位观测,对尖峰岭热带山地雨林更新林生态系统的水文化学循环规律数据分析表明,年均降雨量为2668.3mm,其中总径流量占46.7%,蒸散量53.3%,冠层留量14.0%。N、P、K、Ca、Mg的年均降雨输入量为78.4kg(hm^2.a),总径流输出56.7kg/(hm^2.a),净积累21.6kg/(hgm^2.a),Si,有机C、Al、Mn的年均降雨输入量为25.0kg(hm^2.a) 相似文献
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Community forestry is an approach for mitigating deforestation and forest degradation by managing the forest resources for benefitting neighboring communities. Monetary benefits and costs are associated in a community forest during conservation and management of a forest. For sustainable forest management, the benefit should be more than cost which is a contesting issue of research. So, this study was conducted in a community forest of the central part of Nepal with the help of 80 household surveys and a focus group discussion. The firsthand information collected at the site is complimented by forest product harvest and cost-related secondary information. It was observed that the total annual harvest of timber was 60 cubic feet, pole was 8 cubic feet, firewood was 1,110 Bhari,1 fodder was 4,388 Bhari, and leaf litter was 590 Bhari. To manage a forest, people were involved in fencing, thinning, and meetings. Management cost was six times higher than administration cost. The benefit from firewood and fodder was more due to the dependency of people in a forest for enhancing their livelihood. The higher value of benefit cost ratio indicates that the Community Forest User Group benefited from community forest management. 相似文献
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研究了恒温恒湿处理和浸渍温度对人造板吸水厚度膨胀率检测结果的影响.结果表明:中密度纤维板和刨花板的测定值随着浸渍温度的升高而增大,两者存在着一定的线性关系,而胶合板则受水温影响很小;在浸渍前试件进行恒温恒湿处理与否会影响测试结果.对于刨花板和薄型中密度纤维板,进行恒温恒湿处理是必要的. 相似文献