三江平原湿地的开发对生态环境的影响

论述了湿地的作用及三江平原开发的现状;阐述了由于过渡开发带来的生态环境变换,并提出了保护建议。     

穿过冰冻的阴霾 走向春光的明媚

在冰灾的背影里耕耘绿色 2008年那一场冰灾给高峰林场烙下了一个深深的伤痕! 满山遍野的绿被冰冻肆意摧残，9533公顷相思林面目全非，受灾严重，正在等待春阳的绿色生命顿时陷入了一劫难复的境地，全场直接经济损失达9491万元。一路独领风骚的高峰林场，被这场突如其来的冰冻灾害撞了腰，打了一个趔趄，元气大伤!     

常德市城市道路的绿化现状及存在的问题

针对城市建设对城市道路绿化的要求,根据行道绿化特点和受环境限制的因素,总结了常德市城市道路绿化的现状,指出了目前存在的问题,并提出了一些建议。     

生命的网

茂密的森林,辽阔的草原,环极的苔原带,都栖息着各种各样的动物.哪里的植物丰富多彩,哪里的动物就成群出没. 所有的动物都直接或间接以植物为食,动植物之间的关系十分密切.植物还为动物提供栖居的场所,掩蔽的地方;动物也为植物传授花粉,播散种子,啄除害虫. 生物学家达尔文在英国乡村曾经观察到这样一个有趣的事实:凡是猫养得多的地方,那里的红三叶草就长得特别茂盛.猫和红三叶草,可以说是风马牛不相干,究竟是什么道理呢?细心钻研的达尔文终于发现了这个秘密.原来,红三叶草是专门靠土蜂来传粉的;而土蜂酿的蜜,常常被田鼠偷吃,还破坏了蜂巢.这样,田鼠多了,土蜂就少了,三叶草传粉的机会也少了.鼠的天敌是猫,猫多了,鼠少了,土蜂就多了,红三叶草传粉多了,红三叶草自然就长得繁茂了.     

霜降的霜

越过桂花泡香的虫鸣,“寒露“去了;迈过田野熟稔的童谣,“霜降”来了。也算是24节气中最薄的花朵,霜是地面的水气遇到寒冷天气凝结成的晶体,洁白、冷媚。霜降不是降霜,而是表示天气寒冷,大地将产生初霜的现象。只要降了霜,暮秋的足迹将被彻底覆盖．秋意淡去．一切也就由不得秋风了。是的．一夜醒来,初霜不期而遇。暮秋的花朵一声不吭,如同这淡白的初霜,把冷媚、淡雅挂满树干。减了肥的湖水冒着寒气,瘦了形的山峦漫着雾气．把轻拂的秋风掐断了。     

生存的保障——我的家乡大海林林改印象

林改妙语像孟叔这样将森林承包到个人手中,真的是达到了人与自然的双赢。集体林改革带动了林区的经济发展,解决了部分林区劳动力失业的问题。承包合同制也为林区农户提供了生存的保障,它让林区农户的收入增加了,生活有了奔头。     

春天的搜集

春天象一本永远都翻不完的书。春晖暖透了京郊大地,天地间荡起滚滚春潮,大地捧出了万紫千红的花儿,禾苗儿被阵阵春雨滋润了,树儿撩起了七色的彩裙,婆娑垂柳随风荡漾,鸟儿唱着歌儿飞回了老巢。京东大地,美丽迷人,那是一种青春的色彩,绽放着生命的美丽,那是一种绿色的梦想,在人民心中畅想。     

关于提高采收率的方法的探讨

该文探讨了在采油的过程中提高采收率的方法,特别是对IOR技术和FOR技术进行了分析,指出了技术思路与技术实施的方法。     

三江平原湿地的开发对生态环境的影响

本文阐述了湿地的作用及三江平原开发的现状;由于过渡开发带来的生态环境变化,并且提出了保护及建议。     

我国高新区的现状及存在的问题分析

本文介绍了我国高新区的发展历程,阐述了其取得良好的经济效益、突出的社会效益、高科技产业的发展和高科技产品的产业化及良好制度环境等方方面面的成就.并对我国高新区在过度开发、没有形成产业集群、风险投融资体系尚不健全、技术创新程度低等方向存在的问题进行了分析.     

天牛体内纤维素酶研究进展

文章综述近年来国内外有关天牛体内纤维素酶的研究进展,主要包括:天牛体内纤维素酶的来源、不同天牛种类纤维素酶的性质、纤维素酶抑制剂、纤维素酶同工酶、纤维素酶基因以及天牛体内纤维素酶活性变化与寄主的关系,并展望了未来的研究方向。     

浅议野生动物所有权

野生动物所有权是所有权的一种,它与其他所有权的区别在于客体的不同。文章阐述了野生动物的内涵,分析了野生动物的分类和野生动物与野生动物资源的区别。在明确野生动物含义的基础上,提出了野生动物所有权的概念,深入论述了野生动物所有权与野生动物资源所有权的差异和联系,并对野生动物所有权的主体、客体、内容进行了分析。     

银杏不同品种生长及耐旱性的比较

对6个银杏品种7 a生幼树的树高、干径、1 a生枝长及离体叶片的相对含水量(RWC)和叶绿素稳定指数(CSI)进行研究,结果表明,不同品种的干径和1 a生枝长度的差异达到了极显著水平,干径以大佛手最粗,为2.0824 cm,马铃最细,仅为1.5378 cm;1 a生枝长度最长的是大圆铃达22.9773 cm,最短的是郯城9号,仅为12.0889 cm;马铃的耐旱性最强,CSI为20.67,RWC损失率为65.07%。     

森林资源调查监测综合体系现状分析

对我国现有森林资源调查监测体系现状特点进行了分析,指出现有森林资源调查体系中存在着监测指标综合性不强、技术标准不统一,监测数据管理混乱,监测管理体制不顺,调查队伍素质不高,装备设备落后等问题。提出抓好林业基础数表修编,理顺管理体制、整合监测职能,统一技术标准、加强成果共享,更新技术装备、提高监测水平,明确资金渠道、保证资金投入等对策。     

大兴安岭森林资源变化分析

阐述了人为破坏、过度采伐和自然森林火灾是引起大兴安岭森林资源变化的重要因子;通过对建国初到2002年大兴安岭森林资源在数量上和质量上的变化分析,得出了森林资源变化趋势。森林资源数量减少,且森林质量下降,大兴安岭的森林在经历着破碎化和年轻化的过程。     

枣树叶片营养元素含量的季节变化动态的研究

本文研究了枣树叶片中N、P、K、Ca、Mg、Mn、Cu、Fe、Zn9种营养元素含量的季节变化动态规律。结果表明:全N的含量在初花期以前随着叶龄的增大而迅速降低。在初花期至幼果发育前期较稳定且较低,在幼果发育中期迅速增高,采收后逐渐下降;全P和全K的含量随着叶龄的增加而减小,至叶片成熟后则较稳定;Ca和Mn的含量随着叶龄的增加而迅速增高;Fe的含量在初花期出现低谷,从盛花期到果实发育中期处于稳定的高水平状态,果实进入白熟后逐渐下降,采果后则变动不显著;Mn、Cu和Zn3元素含量的变化趋势与N素水平密切相关;施尿素显著地提高了大多数物候期中叶片全N和Mn的含量,也显著地降低了大多数物侯期中叶片全P、全K和Zn的含量:在年生长周期内,各营养元素的叶分析诊断大多数有2个适宜的采叶时期。     

Native woody species regeneration in exotic tree plantations at Munessa-Shashemene Forest,southern Ethiopia

Regeneration of native woody species was studied in the plantations and the adjacent natural forest at Munessa-Shashemene Forest Project Area, Ethiopia. The aim of the study was to test the hypothesis that tree plantations foster regeneration of native woody species. A total of 60 plots, having 10 × 10 m area each, were studied in monoculture plantations of 4 exotic species (Cupressus lusitanica, Eucalyptus globulus, E. saligna, Pinus patula) and an adjacent natural forest. Ages of the plantations ranged between 9 and 28 years. Soil seed bank analysis was also undertaken from soil samples collected in each of the 60 plots to examine the similarity between the soil seed flora and aboveground vegetation. A total of 56 naturally regenerated woody species were recorded beneath all plantation stands with densities ranging between 2300 and 18650 individuals / ha in different stands. There was a significant difference among plantation stands with regard to understorey density (standard deviation: 4836 ± 1341). Vegetation diversity was assessed through analyses of floristic composition, species richness and abundance. Generally, seedling populations were the most abundant components of the regeneration in most of the plantation stands, forming 68 % of the total regeneration count in all stands. A total of 77 plant species represented by 44 herbs, 13 woody species, 8 grasses and 12 unidentified species were recorded in the soil seed bank from all stands. Similarity between the soil seed bank and aboveground flora was very low implying that the role of soil seed banks is negligible rather dispersal plays an important role in the process of regeneration. These results support the concept that forest plantations can foster the regeneration of native woody species, thereby increasing biological diversity, provided that there are seed sources in the vicinity of the plantations.     

An evaluation of the Acacia albida-based agroforestry practices in the Hararghe highlands of Eastern Ethiopia

Growing Acacia albida as a permanent tree crop, on farmlands with cereals, vegetables and coffee underneath or in between, is an indigenous agroforestry system in the Hararghe highlands of Eastern Ethiopia. However, there is practically no systematic record or data on the merits and benefits of this practice.The paper presents the results of an investigation into the effects of the presence of A. albida on farmlands on the yield of maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench). Twenty seven plot pairs each consisting of one plot underneath the A. albida foliage cover and the other in the open, away from the tree-on farmers' fields, in a 40 km radius around the Alemaya College of Agriculture, were sampled and the yield components analyzed. A statistically significant increase in crops yields by 56% on average was found for the crops under the tree canopies compared to those away from the trees. This increase was caused by the improvement in 1000 grain weight and number of grains of plants under the tree, indicating that the trees enhanced the fertility status of the soil and improved its physical conditions in terms of crop growth.Additional benefits from the A. albida trees include supply of fuelwood and fodder. Quantitative estimates of these outputs as well as their monetary values are presented in the paper. However, in order to realize these benefits to a discernible extent, higher stand densities of the tree than at present are required.Based on an enquiry about the farmers attitude towards A. albida, the prospects for an extension of this promising agroforestry technique are discussed against the background of the state and trends of development of agriculture in the area. It is surmised that despite some shortcomings like the relatively slow and highly variable growth of A. albida and a conflict with the spreading cultivation of Ch'at (Catha edulis Forsk.), the prospects of extension of this technique are good. It is recommended that its propagation should be incorporated into the programmes of the extension agencies of the various governmental agencies concerned with land use.     

大通县退耕还林还草工程实施两年来的问卷调查分析

通过对青海省大通县退耕还林还草工程实施两年来干部、群众对退耕还林还草政策的态度、前景等进行问卷调查 ,发现有 98 5 %的干部、82 2 %的农民赞成退耕还林还草政策 ;绝大多数的干部、近半数的农民认为退耕 8年后的目标还是能够实现的。问卷调查也表明 ,虽然绝大多数干部群众支持退耕还林还草工程 ,但对退耕 8年后的经济效益等也心存疑虑。退耕还林还草工程必须坚持“全面规划、突出重点、宜林则林、宜草则草、林草复合”的方针 ,努力做到四个“确保” ,才能真正实现“退得下、稳得住、不反弹、能致富”的退耕还林还草总体目标     

我国薪炭材树种的热值与生态差异的研究

本文对木材热值的测定方法进行了研究。为了提高试验的精确度,改进了试样的容器;减少试样辅助添加剂引入的误差;考虑了含脂材挥发物对热值的影响,提出了一个实际通用的测试方法。通过对二十四种样木的测试,综合分析了测试误差、生态差异以及营林因子等的影响,对薪材热值的树种间差异和生态因子对热值变异时影响进行了研究。