关于吉林林区水泥混凝土路面的发展问题

作者对吉林林区红石，泉阳，白河等林业局辅助的水泥混凝土路面进行了调查，发现路面板块产生断裂，碎裂，错台和脱皮等现象，并对这种现象从理论上作了分析，反映出了路面的设计板厚和施工质量是确保设计使用年限的关键。     

开发职业技能为林区经济发展服务

职业技能开发的根本任务是提高劳动者的素质,促进其就业能力和工作能力.     

对林区投资的分析与探讨

本文论述了林区的投资现状.并对其进行了分析.找出了近期林区固定资产投资的弊端.提出了扩宽林区今后投资的筹资渠道,并建立集团公司的资本金制度、加大招商引资力度.在投资的运用方面.提出要认真研究林区的保险投资问题,在加强固定资产投资的运用及投资原则上也提出了很好的建议.在投资管理上提出了建立林区建设项目库的新思路.     

草苁蓉的人工繁育

1草苁蓉简介 草苁蓉天然分布区极窄,世界上只在中国、日本、朝鲜和俄罗斯有一定量的分布,在我国也只有长白山林区(海拔1100～1300 m)、大兴安岭北部林区(海拔350～550 m)有天然的分布.其中长白山林区由于人为破坏严重,目前资源已近枯竭.大兴安岭林区也出现了乱采乱收的无序状况,使有限的野生资源受到侵害.     

乳源县五指山林区的森林群落类型

乳源县五指山林区按垂直分布,其林木复合群落有4种类型:1.常绿阔叶林复合群落;2.常绿阔叶树种与落叶阔叶树种混交林木本群落;3.针阔叶混交林木本群落;4.常绿落叶阔叶矮林复合群落。本文对每种类型的海拔高度、林地土壤和主要树种等分别作了介绍。     

建立和完善我区林产品市场体系的探讨

自治区党委六届三次全委(扩大)会议提出了实行“两个转变”,实现“两个提高”,完成两大历史性任务的宏伟目标.这是我区当前最大的政治.这就要求重点去抓与“两个转变”、“两个提高”关联度大的工作.本文就林业如何建立和完善以木材为主的林产品市场体系问题,做以下分析探讨.一、我区林产品市场现状及存在的主要问题由于森林具有经济、社会、生态三大效益,森林采伐不能单纯从经济效益一个方面考虑,因此决定了木材等林产品也具有特殊性.一是在产品品种规格上,还不能完全象工厂产品一样,完全按市场需求确定生产;二是在产品数量上,要受到森林采伐限额的     

林区作业方法的发展

1 进入林区的途径 任何的林区作业都必须有进出林区的途径。 在谈其它交通途径之前,人类面临着这样的诱惑:运用悬吊的藤蔓象动物一样在树丛中移动。人们在打猎或者是被追击时,可以利用这些悬吊的藤条使他们迅速的越过障碍。使道路简单,减轻了工作强度。后来,森林中的原始人开始利用绳索技术。藤本植物和其它悬吊的藤被运用为悬空桥或者用来将材料和人运过复杂的地形。     

大兴安岭林区公路的环境保护

本文重点论述了林区公路在设计、选线等方面.要注意保护自然环境.所选择线路应与地形和自然环境相协调.防止由于修建林区公路而造成水土流失.提出了林区公路设计时保护环境的设计方法。     

太岳山林区不同造林模式推广与应用

推广应用科学的造林模式,不仅能够提高造林成活率,还可以加快成林进程.介绍了太岳山林区以油松、落叶松为主的针叶林,以刺槐与连翘为主的阔叶林和以核桃为主的经济林造林模式.     

对内蒙古大兴安岭林区开发人造板工业的探讨

内蒙古大兴安岭林区开发30多年来,为国家提供了大量的木材和其它林产品,有力地支援了国家的经济建设.但是,由于长时期过量采伐,林区可采资源锐减,企业逐渐陷入了资源危机与经济危困.为了摆脱林区的“两危”,笔者拟就开发人造板工业问题提出一些粗浅看法,供同行参考.     

Trophic control of bud break in peach (Prunus persica) trees: a possible role of hexoses

Vegetative buds of peach (Prunus persica L. Batsch.) trees act as strong sinks and their bud break capacity can be profoundly affected by carbohydrate availability during the rest period (November-February). Analysis of xylem sap revealed seasonal changes in concentrations of sorbitol and hexoses (glucose and fructose). Sorbitol concentrations decreased and hexose concentrations increased with increasing bud break capacity. Sucrose concentration in xylem sap increased significantly but remained low. To clarify their respective roles in the early events of bud break, carbohydrate concentrations and uptake rates, and activities of NAD-dependent sorbitol dehydrogenase (SDH), sorbitol oxidase (SOX) and cell wall invertase (CWI) were determined in meristematic tissues, cushion tissues and stem segments. Only CWI activity increased in meristematic tissues shortly before bud break. In buds displaying high bud break capacity (during January and February), concentrations of sorbitol and sucrose in meristematic tissues were almost unchanged, paralleling their low rates of uptake and utilization by meristematic tissues, and indicating that sorbitol and sucrose play a negligible role in the bud break process. Hexose concentrations in meristematic tissues and glucose imported by meristematic tissues correlated positively with bud break capacity, suggesting that hexoses are involved in the early events of bud break. These findings were confirmed by data for buds that were unable to break because they had been collected from trees deprived of cold. We therefore conclude that hexoses are of greater importance than sorbitol or sucrose in the early events of bud break in peach trees.     

广西雅长林场防火林带树种选择与密度确定方法

营建生物防火林带是预防森林火灾蔓延、减少经济损失的有效方法，科学地选择防火树种和合理确定林带密度则是营建生物防火林带的关键。以广西国有雅长林场为研究对象，提出了基于理想点评价方法的防火树种选择和地理信息系统支持下的防火林带密度确定方法，结果表明：借助于现代决策方法与地理信息系统技术，可使防火树种的选择和林火阻隔网合理密度确定更为科学、客观、合理。     

科学发展给力油茶产业发展方式转变

针对目前油茶产业发展中存在的问题,用科学发展观的思想理念,提出了＂10个突破,10个增强＂,即：突破油茶是小品种油的思维定势,增强油茶大产业意识;突破油茶是＂露水财＂的思维定势,增强＂绿色银行＂意识;突破传统发展思维定势,增强科技发展意识;突破小户经营思维定势,增强集约化经营意识;突破粗放经营思维定势,增强园艺化管理意识;突破节点发展思维定势,增强产业链发展意识;突破无机发展思维定势,增强有机生态发展意识;突破手工耕种思维定势,增强机械化、自动化耕种意识;突破单纯发展油茶思维定势,增强复合发展意识;突破低端产品思维定势,增强高端品牌发展油茶产业意识。从而促进油茶产业又好又快发展。     

Photoperiodic control of seasonal development and dormancy in tropical stem-succulent trees

Tropical stem-succulent trees store large quantities of water in their trunks yet remain leafless during the early and mid dry season. In contrast to most other tropical trees, bud break of vegetative buds is not induced in fully hydrated stem succulents between the winter solstice and the spring equinox by leaf abscission, abnormal rain showers or irrigation. Vegetative buds of leafless trees are therefore in a state of endo-dormancy similar to that of temperate perennial plants during early winter. Highly synchronous bud break regularly occurs soon after the spring equinox, often weeks before the first rainfalls of the wet season. These observations suggested that endo-dormancy and bud break might be induced by declining and increasing photoperiods after the autumn and spring equinoxes, respectively. In phenological field observations, we confirmed highly synchronous bud break after the spring equinox in many trees of five stem-succulent species in the northern and southern hemispheres. Shoot growth of potted saplings of Plumeria rubra L. was arrested by a decline in day length below 12 h after the autumn equinox, but continued in saplings maintained in a 13-h photoperiod. Conversely, exposure to a 13-h photoperiod induced bud break of dormant apical buds in saplings and cuttings in January, whereas plants maintained in the natural day length of < 11.7 h remained dormant. Photoperiodic control of endo-dormancy of vegetative buds in stem succulents is thus supported by field observations and experimental variation of the photoperiod. At low latitudes, where annual variation of day length is less than 1 h, bud dormancy is induced and broken by variations in photoperiod of less than 30 min.     

Seedling cold hardiness, bud set, and bud break in nine provenances of Pinus greggii Engelm.

Cold hardiness and timing of bud set and bud break are important processes that provide protection of nursery seedlings against low temperatures. Seedlings of 9 provenances of Pinus greggii from two different regions of Mexico were tested to determine cold hardiness, bud set, and bud break timing differences. Needle sections were exposed to freezing temperatures to determine an injury index of each provenance. In addition, bud set and bud break timing were recorded through the fall, winter and spring. There were significant differences in cold hardiness between seedlings from northern and southern provenances. At the maximum cold hardiness, the index of injury (LT₅₀) for northern provenances was LT₅₀ = −18 °C, compared to −12 °C for southern provenances. There was a considerable variation among the provenances in the proportion of seedlings that set terminal buds. Seedlings from northern provenances had greater proportions of seedlings that set a terminal bud than seedlings from southern provenances. There were also significant differences in the bud break timing in the following spring among the 9 provenances. Seedlings from northern provenances broke bud earlier than southern provenances. Cold hardiness, bud set, and bud break timing results may be useful to determine how far a specific seed source can be moved from its natural environment.     

Preformation in vegetative buds of Prunus persica: factors influencing number of leaf primordia in overwintering buds

We investigated the influence of bud position, cultivar, tree age, tree carbohydrate status, sampling date, drought and light exposure on the number of leaf primordia formed in dormant vegetative peach buds (Prunus persica (L.) Batsch) relative to the number of primordia formed after bud break (neoformed). During winter dormancy, vegetative peach buds from California and Italy were dissected and the number of leaf primordia recorded. Between leaf drop and bud break, the number of leaf primordia doubled from about five to about 10. Parent shoot length, number of nodes on the parent shoot, cross-sectional area of the parent shoot, bud position along the parent shoot and bud cross-sectional area were correlated with the number of leaf primordia. Previous season light exposure, drought and tree carbohydrate status did not affect the number of leaf primordia present. The number of leaf primordia differed significantly among peach varieties and tree ages at leaf drop, but not at bud break. Our results indicate that neoformation accounted for all shoot growth beyond about 10 nodes. The predominance of neoformed shoot growth in peach allows this species great plasticity in its response to current-season conditions.     

Seasonal changes in intensity of bud dormancy in loblolly pine seedlings

The terminal buds of six-month-old loblolly pine (Pinus taeda L.) seedlings remained closed for approximately six months, although bud dormancy, as measured by rate of bud break in a standard greenhouse environment, was only exhibited for about one month. The peak of bud dormancy was in December for seedlings grown near Auburn, Alabama. However, the timing and intensity varied with seed source and may have been affected by the warm fall temperatures. Seedlings from the more northern provenances entered dormancy first and reached a deeper state of dormancy than seedlings from southern provenances. The rate of shoot elongation was not consistently related to the rate of bud break.     

防火林带的应用与研究现状

综述了防火树种选择的方法、防火林带选用的树种、防火林带的结构与配置、林带宽度和网格、防火林带阻火机理的研究现状以及防火林带在我国的应用与发展前景。     

Variations in amounts of carbohydrates, amino acids and adenine nucleotides in mulberry tree (Morus alba L.) stems during transitional phases of growth

Quantitative changes in carbohydrates, amino acids and adenine nucleotides in the stems of mulberry trees (Morus alba L., cv. Shin-ichinose) were followed from spring to early summer and from autumn to early spring. Both ATP and ADP content of stems increased before bud break, whereas the content of sucrose, the most abundant sugar among the stem carbohydrates, decreased. The sucrose content fell to its lowest value at the beginning of May, and then increased rapidly, whereas the starch content decreased suggesting consumption of reserve carbohydrate and simultaneous accumulation of current photosynthate. This was confirmed by studies in which reserve carbohydrates were labeled with (14)CO(2). Proline content of stems increased from the time of leaf shedding until early spring. Although it was the most abundant amino acid at the time of bud break, proline rapidly decreased as new shoots developed and was hardly detectable by the beginning of May. The asparagine and arginine contents increased transiently following bud break, and then decreased toward summer. Transient increases in glutamine and arginine were noted at the time of leaf shedding.     

嵊州市雷竹雪灾灾情分析与灾后恢复措施探讨

2008年1月中旬至2月上旬的连续低温雨雪天气造成严重的雪灾,使嵊州市3133 hm2雷竹林受到不同程度的影响,样地调查发现,雪灾造成雷竹林25.70%的母竹倾斜和折断;不钩梢竹林在雨雪过程中未采取摇雪处理的母竹倾斜和折断比例高达64.83%,采取摇雪处理的其比例仅为18.18%;钩梢竹林在雨雪过程中未采取摇雪处理的母竹倾斜和折断比例则下降为41.62%,采取摇雪处理的其比例则更低,仅为13.93%.表明在雷竹林经营过程中,钩梢对抵抗雪压效果明显,而在雨雪天气进行摇雪处理效果更为明显.受灾雷竹林2008年笋产量明显低于2007年,单位面积笋产量下降38.28%.通过对雷竹林受灾情况的分析,提出了雷竹灾后恢复技术措施.