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浅谈林区便道路基排水现状与养护对策 总被引：1，自引：0，他引：1
林区便道养护的关键是解决路基排水问题,根据林区便道路基的排水现状,分析了影响林区便道路基排水的主要因素,并提出相应的养护对策。 相似文献
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加强林区公路的路基养护是开发林区，加速林业生产建设，保护森林、繁荣山区经济的重要措施。本文对公路路基排水，对坍方地段，沿河地段路基的养护等进行了论述。 相似文献
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加强林区公路的路基养护是开发林区，加速林业生产建设，保护森林，繁荣山区经济的重要措施。本文对公路路基排水，对坍方地段，沿河地段路基的养护等进行了论述。 相似文献
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本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(2):158-165
The short-term effect of thinning on cronartium rust on Scots pine ( Pinus sylvestris L.) was investigated in a stand of Scots pine (artificially seeded and in the pole-stage) severely infected by the stem-rust fungus Cronartium flaccidum (Alb. & Schwein) G. Winter. The disease rate (the number of old and fresh infections) was recorded before thinning, after which all trees with a resin-top as well as all individual branches with sporulating lesions were removed from the thinned plots, while the comparison plots remained non-thinned. The numbers of sporulating lesions were recorded on the plots annually for 2-5 yrs after thinning. Thinning had no significant short-term effect on the year-to-year relative number of sporulating lesions. The relative number of sporulating lesions, however, increased in both thinned and nonthinned trees, varying significantly from year to year. Thinning had no significant effect on the year of formation of the shoot bearing annual sporulating lesions, the duration of sporulation or the growth of the fungus along the infected shoot in perennial lesions during the first 5 yrs after the treatment. 相似文献
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森林冠层结构与功能及其时空变化研究进展* 总被引：16，自引：0，他引：16
林冠是森林与外界环境相互作用最直接和最活跃的界面层 ,同时 ,它本身又承载了森林生物多样性的主体部分。森林冠层研究的方法和技术在近些年取得了长足发展 ,从而促进了有关林冠结构与功能的研究。这些研究深化了人们对于林冠结构与光能截获以及群落干物质积累之间关系的认识 ,同时 ,对于森林冠层的物质循环和能量传输以及冠层内各营养级之间相互关系动态也有了更为深入的理解。考察森林冠层的结构与功能及其时空变化是深入理解整个森林生态系统的格局、过程及其运作机制的重要基础。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):436-445
Accumulation of cadmium (Cd), lead (Pb) and mercury (Hg), as affected by organic matter content, pH of different soil compartments and the physicochemical properties of each metal, was studied in different soil types within two forested catchments of the Norway spruce (Picea abies - Vaccinium myrtillus) type. Independent of soil type, the highest metal concentrations were found in the organic layers of the soil, usually in the surface soil. The concentrations in the upper part of the mineral subsoil were about one-fifth to one-tenth, or less, of those in the organic surface soil. Concentration maxima in the B-horizon were more pronounced for Cd and Hg than for Pb. When comparing soil types, the highest concentrations of Cd were found in the less acidified fens in the discharge area, while for Hg and Pb the highest concentrations usually occurred in the mor layer of the well-drained Podzols. For all metals, the soil types with the largest accumulation had concentrations up to 2-3-fold higher in the organic layers than those with the smallest accumulation. 相似文献
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IntroductionDuringthepasttwodecades,studieshaverevealedthatgrowingash(Fnainusmandshurica)andlarch(LarlksPP.)togetherinaproperwaycanincreasetheproduc-tivityQfthestandsI"'}'-'].Theyieldimprovementmechanismsattributetotwoaspects,i.e.,theabovegroundandundergr… 相似文献
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方文彬 《中南林业科技大学学报(自然科学版)》1995,(2)
采用碘溶液和氢氧化钠两种溶液的混合液处理针叶树材管胞弦壁切片，并用干燥法脱除切片胞壁水，对碘结晶法测量木材微纤丝角的方法进行改良．结果表明，切片的木素脱除干净彻底，次生壁微纤丝之间易形成空隙，有利于碘离子进入其中形成碘结晶，可清晰地观察到微纤丝的走向，有利于有效而准确地测量微纤丝角，与改良前进行比较，具有省时省力，节约经费的优点． 相似文献
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Xinglian Geng Ryuichiro Kondo Kokki Sakai Zhongzheng Lee 《Journal of Wood Science》1999,45(2):143-148
A strain of the fungusCoriolus versicolor was inoculated periodically into potato dextrose agar (PDA) slants containing the effluent to enhance the natural ability to grow in the effluent. The acclimated strain grown in the 50% effluent-containing PDA slant and the original strain were employed to treat the effluent. The acclimated strain could grow in a higher concentration of the effluent than the original unacclimated one. Both the original and acclimated strains improved the dispersing ability of the effluent, especially the acclimated strain because of its higher laccase secretion. The dispersing ability of the SFP effluent was improved to a level comparable to a commercial lignosulfonate product because it was strongly polymerized by the fungus. During the fungal treatment, more than 50% of the sugars were removed from the effluent, thereby increasing the purity of the SFP lignin product.This work was presented at the 48th annual meeting of the Japan Wood Research Society, April 3–5, 1998, Shizuoka, Japa 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):457-469
The persistence of the four herbicides atrazine, hexazinone, lenacil and linuron was studied in forest nursery soils. The adsorption capacities of the soils for the chemicals were described by the distribution coefficients kj and koc. Due to the low content of organic matter in the soils the ka‐values were low, in several cases being <1 for hexazinone. Hexazinone also had the lowest k oc‐value (30) while the other substances had koc ‐values within the range 200–400. In some cases hexazinone showed great mobility under field conditions. The formula c=co‐kt1/2 was used to describe the disappearance of the herbicides from the various soils. The rate of degradation of the four herbicides correlated well with the rate of respiration in the same soils in laboratory experiments, and for linuron reasonably well also in field experiments. In the field experiments the herbicides penetrated the top soil layer. In the subsoil the risk of further transport downward to the drainage system or ground water increased, especially for hexazinone. Linuron as well as the fungicides maneb and tolylfluanid suppressed the decomposition rate of hexazinone in laboratory experiments. 相似文献
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Pedro Ah Shenga Peter Bomark Olof Broman Dick Sandberg 《Wood material science & engineering》2017,12(4):257-262
The sawmill industry is a very important link in the Mozambique forest products value chain, but the industry is characterized by undeveloped processing technology and high-volume export of almost unrefined logs. The low volume yield of sawn timber has been identified as a critical gap in the technological development of the industry. To improve the profitability of the industry, there is thus a need to develop methods and techniques that improve the yield. In this paper, different positioning of logs prior to sawing and the possibility of increasing the volume yield of crooked logs by bucking the logs before sawing have been studied. A computer simulation was used to study the cant-sawing and through-and-through sawing of the logs to determine the volume yield of sawn timber from the jambirre (Millettia stuhlmannii Taub.) and umbila (Pterocarpus angolensis DC.) species. The optimal position, i.e. the position of the log before sawing that gives the highest volume yield of sawn timber for a given sawing pattern when the positioning parameters, offset, skew and rotation, are considered gave a considerable higher volume yield than the horns-down position. By bucking very crooked logs and using the horns-down positioning before sawing, the volume yield can be of the same magnitude as that obtained by optimal positioning on full-length (un-bucked) logs. The bucking reduces the crook of the logs and hence increases the volume yield of sawn timber. 相似文献