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南斯拉夫共有杨柳树林地15万公顷,仅占森林面积的1.5%,但其木材产量却占全国木材总产量的8%。杨木产量由1950年的10立方米,提高到1985年的120万立方米,增加了11倍,成为当今国际杨树委员会的重要成员国之一。该国杨树发展速度之所以快,与其有一支稳定的科研队伍密切相关。本文较详细地介绍了南斯拉夫杨树育种的成就和经验,并结合我国的实际情况,提出了作者的看法和建议。 相似文献
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我国桉树木材性质及其变异规律研究进展 总被引：1，自引：0，他引：1
概述了国内桉树木材解剖性质、物理力学性质、化学性质及其变异规律的研究现状,对桉树木材性质变异的影响因子及其材性遗传相关性研究进行了总结,最后分析其存在的问题,并展望了桉树材性遗传改良的研究前景。 相似文献
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美洲黑杨及其杂种在世界和我国杨树栽培中的地位与作用 总被引：2，自引：0，他引：2
本文介绍了美洲黑杨的天然分布, 生长状况。西欧各国对其珍贵基因资源的重视和利用, 我国引种美洲黑杨的现状及其作用等, 并对我国进一步利用美洲黑杨的基因资源, 促进我国杨树栽培的发展提出了一些看法。 相似文献
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以德国南部小城镇加米施-帕滕基兴(Garmisch-Partenkirchen)市为例,在介绍该市园林绿化概况的基础上,重点介绍其民居庭院绿化与阳台绿化的特色;并对如何更好地发展中国小城镇绿化进行了探讨。
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衡阳市山河水库综合治理及开发利用研究 总被引：5，自引：0，他引：5
由于生态环境的不断恶化 ,厄尔尼诺事件加强 ,造成大气污染而形成大量酸雨 ,使大片森林和农作物被酸雨腐蚀致死 ,从而加重了生态的恶性循环 ,导致了自然灾害频繁。仅从 1994 -1998年 5年的旱涝灾害就给我市造成了 90多亿元的重大经济损失和死亡 2 2 8人。开展对该项目的研究 ,就是要加大对生态林业建设的投入 ,对山河水库及小流域进行综合治理 ,通过生态、生物和工程措施 ,有效地控制水土流失 ,创造一个良好的生态环境 ,为我市的工农业生产及国民经济的可持续发展提供基础保障。 相似文献
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园林植物病虫害发生特点与防治进展 总被引：7，自引：0，他引：7
本文从园林植物病虫害防治的重要性入手,分析了园林植物病虫害的特点,指出了园林植物病虫害防治的发展方向,为今后开展园林植物病虫害防治工作提供了有益的借鉴。 相似文献
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澳大利亚辐射松遗传育种及其借鉴 总被引：1，自引：0，他引：1
澳大利亚辐射松遗传改良在过去的几十年中取得了较大的成绩, 其育种计划与育种策略在一定程度上反应了当前世界林木育种水平。较详细地介绍与分析了澳大利亚辐射松遗传改良的历程与成就, 供我国林木育种工作者参考。 相似文献
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Forest cover change is one of the defining contemporary environmental changes that validate the proposition of the Anthropocene narrative. Forest transition is a well-recognized global phenomenon, which has been studied and explained in well elaborated forest transition theory. Forest transition has been observed in over 30 countries, and it has been a trend in multiple countries in Asia. Forest transition is most relevant for the Anthropocene narrative, as it suggests that forest cover decline may eventually be followed by a forest cover increase at the global scale. The paper reviews evidence of forest transition in eight Asian countries and juxtaposes this with global forest cover trends. In Asia countries like China, India, Japan, Philippines, South Korea, and Japan and Vietnam are among the countries that have experienced an increase in the area under some kind of tree cover. Complex interplays of forest cover, population growth, economic development, demand for forest goods and services and governance effectiveness are the driving forces of forest transition. While it is not possible to extrapolate Asia's forest transition to the global scale, the Asian experience makes it possible to make statements on possible global forest cover scenarios. Ultimately, forest transition theory in general, and the experience of forest transition in Asia also support the concept and related narrative of the Anthropocene. 相似文献
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Natural mortality in thinning and fertilisation experiments with pine and spruce in Sweden 总被引：1，自引：0，他引：1
Natural mortality in a 30-year period was examined in thinning and fertilisation experiments with 48 blocks in Scots pine (Pinus sylvstris L.) and 23 blocks in Norway spruce (Picea abies (L.) Karst.) with up to 12 different treatments. Of about 90,000 living trees at start of the experiments 18.7% were registered as dead by natural mortality in the 30-year observation period. In non-thinned stands about 20% of the volume growth disappeared by natural mortality, in thinned stands about 10%. In normally thinned pine stands (repeated thinning from below with moderate intensity) the annual mortality of the basal area at start of an average 7-year period was 0.34%. In spruce stands, on more fertile sites, the corresponding figure was about 0.6%. In an effort to model the mortality, severe damage not leading to final felling was identified in 1.7% of the observation periods. It was assumed that this part of the mortality, representing 24% of the total volume mortality, could be recovered by active thinning. The probability for severe damage increased sharply with stand top height, as shown in a logistic regression. The more sparse mortality was expressed as a function of site fertility, stand density, disturbance by thinning and form of treatment (thinned from above or below or non-thinned). The naturally dead trees were approximately of mean size in normally thinned stands while the self-thinning in non-thinned stands tended to occur amongst smaller than average trees. Diagrams were presented for basal area development and stem number reduction in the non-thinned stands. 相似文献
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Nyam-Osor Batkhuu Don Koo Lee Jamsran Tsogtbaatar 《Journal of Sustainable Forestry》2013,32(6):600-617
Since 1990, after the dramatic change in Mongolia's political and economic system, human impact on forest resources highly increased and became continuously degraded due to improper exploitation, forest fire, mining, pest and disease, uncontrolled grazing, and inadequate management which negatively affect its environmental conditions causing severe deforestation, desertification, and ecological stress in some regions of the country. Forestry research and education became fragmented in Mongolia. Several institutions and universities conducted vague and in some cases duplicating research topics. Hence, this article aims to understand the current status and issues as well as to formulate possible solutions in strengthening and developing forest and forestry research and education in the country. 相似文献
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Public participation in regional and local forest planning in Finland was researched. The questions were: (1) What is the purpose of public participation? (2) What are the challenges of public participation? The results are based on the analysis of discourse communities in a case study concerning a Regional Forest Programme and forest management planning. It was shown that the purpose of participation was to promote communication at the regional level and to gather information at the local level. The general conclusion is, that the regional forest programmes include practices to offer possibilities for communication among participants. This does not mean, that all the programme processes have reached consensus automatically. The case studied here reached compromise. The case study points out problems faced, if public participation would become common practice at the local level on non-industrial private forests lands. In forest management planning it would result in an excessively demanding mediator/expert role for the planner. The need to consider all relevant issues, e.g. biodiversity management, would also become apparent. The study supports the idea that public participation as communication has better possibilities to promote sustainable forest management than public participation as information gathering. 相似文献
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Changes in susceptibility to wind and snow damage due to thinningand fertilization were examined in even aged Norway spruce (Piceaabies (L.) Karst.) stands in southern Sweden. The stands arepart of a nationwide experiment to investigate growth and yieldfollowing different thinning and fertilization regimes establishedbetween 1966 and 1983. The material used in this study included16 replications of seven treatments. The treatments were: threelevels of thinning from below (20–70 per cent); 20 percent thinning from above; thinning from below in combinationwith N and NP fertilization (thinning percentage 25–28per cent); and unthinned control. The stands have been censusedtwice for damage during an average period of 12 years. The degree of wind and snow induced damage varied between 9and 20 per cent of the basal area increment produced duringthe observation period. For treatments with high basal arearemoval, the highest relative number of trees damaged by windoccured during the first period after thinning. The denseststands (i.e. unthinned controls and stands thinned from above)showed a high proportion of snow damage throughout the observationperiod. The block effect was in general more significant thanthe effect of treatments on damage level. When analysing theinfluence of the block effect (i.e. of site and stand characteristics)on damage level, wind damage was best predicted by stand basalarea left after thinning and stand age, while snow damage wasbest predicted by latitude, altitude, site index, and standage. On average the tested site and stand characteristics explained17 per cent of the variation in wind damage and 36 per centin snow damage. 相似文献
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我国竹材加工利用要重视“科学”和“创新” 总被引：12，自引：0，他引：12
综述了我国竹材资源和加工利用的现状 ,指出我国竹材加工利用要重视“科学”和“创新”。各企业只有充分利用当地的地区优势和竹资源的特点 ,进行科学和合理的加工 ,开发出各种性能、价格比优于木材的适销对路的竹材产品 ,特别是有自主知识产权的创新产品 ,才能适应我国加入WTO以后的市场竞争。 相似文献
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Ginkgo (Ginkgo biloba L.) is a multi-value deciduous tree species grown for the production of nuts, timber and foliage for medicinal products. Understanding
the ecological and biological basis for Ginkgo agroforestry systems is essential for the design of optimum Ginkgo-crop species
combinations. We established two greenhouse replacement series to examine interactions between Ginkgo and wheat (Triticum aestivum L.); and Ginkgo and broad bean (Vicia faba L.). The results showed that crop species were more competitive than Ginkgo at low Ginkgo density, but less competitive than
Ginkgo at high Ginkgo density. Ginkgo: wheat ratio 5:1 and Ginkgo: broad bean ratio 5:1 had relative yield total (RYT) and
relative land output (RLO) values of more than one and the largest total land output (TLO) values in respective mixtures.
Therefore, these two ratios might be considered optimum Ginkgo: crop ratio for enhancing the combined biomass of the Ginkgo
and crop in respective mixtures. Broad bean and wheat were more competitive than Ginkgo, which was less affected by wheat
than by broad bean. However, there were compensatory interactions between Ginkgo and wheat, and Ginkgo and broad bean. There
was significant belowground competition for soil N between Ginkgo and the two crop species in the Ginkgo/crop mixtures. The
two mixtures outperformed monocultures of the individual species when comparing the mixtures with the crop monoculture system. 相似文献
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D. G. Hunt 《Wood Science and Technology》1989,23(4):323-333
Summary Non-linearity of softwood in axial mechano-sorptive creep during moisture cycling can be characterised as departure from linear behaviour. Linear behaviour is shown by experimental measurement to be a gradual approach to a creep limit with exponentially decreasing increments of compliance, Ji, per moisture cycle, when tested under a constant stress. On the other hand, when the stress is progressively increased by a small increment after each moisture cycle, the compliance increments will progressively increase, having a value of
, where n is the cycle number. By subtracting one compliance increment from the succeeding one, the value of Ji can be obtained. Analysis of experimental results in bending tension and compression showed that the compression test pieces departed from linearity at total strains around 0.14% to 0.15%, the bending test pieces showed slight evidence of non-linearity at about the same strain, whilst the tensile pieces were approximately linear up to 0.18% strain.This project was supported by the U.K. Science and Engineering Research Council and by the European Commission 相似文献
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The phenology of 5- and 6-year old loblolly pine (Pinus taeda L.) trees was studied over two different growing seasons (1993 and 94) in southwest Georgia. These trees were from 7–9 open-pollinated families from each of four different provenances planted at two locations. The provenances were: Atlantic Coastal Plain (eastern SC), Gulf Hammock (north FL), Lower Gulf (south AL, MS) and Upper Gulf (north AL, MS). Provenances did not vary as to when height growth started in spring, but showed very significant differences for the date of growth cessation in fall. The Gulf Hammock source grew the most and also had the longest height growth period, while the Upper Gulf source was first to stop height growth and had the least annual height increment. Provenances were also significantly different for the date of cessation of diameter growth (a difference of 22 days between Gulf Hammock and Upper Gulf), and the order of cessation was the same as for height. Families within provenances were significantly different for date of cessation of height growth and diameter growth. When family means were considered across provenances, there was a correlation of 0.69 (p-value = 0.0001) between annual height increment and date of height growth cessation. There was a weaker association between faster growth and a longer growing season within provenances. 相似文献