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。     

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。     

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。     

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。     

最美的颜色

作为全国的政治经济文化中心,随着中国的改革开放与进步,北京一次又一次地吸引了全世界的目光。“绿色北京,绿色奥运”,2001年那个火热的夏天,满怀期望的北京向全世界发出了邀请。四年过去了,充满无限生机与活力的北京又为我们带来了什么呢?当然是绿色,那片片相连,波澜壮阔的绿色海洋,用无声的语言向热爱她的人们挥手致意。49.99%的绿化覆盖率,让北京变成了一个城市内外绿荫环绕,处处鸟语花香的大花园。每年数百万群众走进大自然,用自己的双手为美丽的北京编织绿色的衣裳。长久以来靠山吃山的农民富了,原本荒凉贫瘠的大山绿了,吸引了那么多城里人甚至外国人来这里旅游,朴实真诚的北京人捧出诱人的大桃、金黄的梨、紫红的葡萄、红得发艳的苹果,来招待四面八方的客人。     

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!     

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。     

对我国林业生态的保护及经济发展的思考

指出了林业作为我国经济发展的一个重要组成部分,是一项重要的公益事业和基础产业,分析了目前我国林业经济发展的现状,探讨了森林资源严重不足和森林质量下降等问题,提出了相应的对策.     

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.     

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。     

Canopy management possibilities for arboreal Leucaena in mixed sorghum and livestock small farm production systems in semi-arid India

A major problem for small farmers in the semi-arid tropics is the chronic shortage of fodder for draft animals. Leucaena leucocephala has improved productivity in many places in India and in various cropping systems, usually as either a pure crop or in a hedgerow alley-cropping configuration. Mixed cropping with arboreal forms is seldom seen. For off-season fodder production, hedgerows have the disadvantage of being open to unmanaged browsing when unfenced (as is usual). Arboreal forms are generally far less vulnerable. In this paper, the components of production of sorghum and arboreal Leucaena are measured under different intensities of canopy lopping. The most productive management system of those examined was pollarding of the Leucaena at the time of under-sowing with sorghum. In a year with less than 50% of average seasonal rainfall, this system gave a yield of 4.6 tonnes/ha/yr fresh wt fodder and 3.8 tonnes/ha/yr dry wt. of fuel harvests, while increasing the standing crop of wood by 1.8 t/ha/yr and retaining a yield of sorghum grain equivalent to 46% of pure sorghum cropping; the LER of this system was 1.35. Cash values of the alternative management systems were estimated, including the discounted Net Present Value of the standing crop of timber. Maximum value was attained with unlopped pure crop Leucaena followed by pollarded Leucaena with sorghum; pure crop sorghum achieved a lower value. These results demonstrate both the high productivity of Leucaena/sorghum based systems, and the stability of production even in poor rainfall conditions. Pollarding transferred the high future value of Leucaena timber to the present value of sorghum grain and fuelwood.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

瓜州绿洲植被退化原因及保护对策

瓜洲县近年来人口数量增长和土地开发规模过大,成为水资源紧张、植被退化、生态环境质量下降的重要原因之一,对绿洲农业生产和人居环境影响很大,因此,严格控制人口数量的增长和土地开发规模,大力发展节水农业,保障生态供水,加强对现有植被的保护,维护生态平衡,是瓜洲县实现可持续发展必须认真考虑的问题。     

Using degree-day accumulations and host phenology for predicting larval emergence patterns of the olive psyllid, <Emphasis Type="Italic">Euphyllura phillyreae</Emphasis>

The olive psyllid, Euphyllura phillyreae Foerster is one of the most destructive pests on buds and flowers of olive tree (Olea europaea L.) in May when the olive growers cannot apply any insecticides against the pest. Temperature-dependent development of the psyllid was studied at constant temperatures ranged 16–26°C. A degree-day (DD) model was developed to predict the larval emergence using the weekly cumulative larval counts and daily mean temperatures. Linear regression analysis estimated a lower developmental threshold of 4.1 and 4.3°C and a thermal constant of 164.17 and 466.13 DD for development of egg and larva, respectively. The cumulative larval counts of E. phillyreae approximated by probit transformation were plotted against time, expressed as the sum of DD above 4.3°C, the starting date when the olive tree phenology was the period of flower cluster initiation. A linear model was used to describe the relationship of DDs and probit values of larval emergence patterns of E. phillyreae and predicted that 10, 50 and 95% emergence of the larvae required 235.81, 360.22 and 519.93 DD, respectively, with errors of 1–3 days compared to observed values. Based on biofix depends the development of olive tree phenology; the DD model can be used as a forecasting method for proper timing of insecticide applications against E. phillyreae larvae in olive groves.     

我国竹类植物种质保护体系的适度理念研究

竹类是一类具特殊生长习性与生长型的植物,其分布范围广泛、有性生殖脆弱而无性繁殖发达,易于受到人为和自然因素的影响而沦为小种群或濒危物种。本文从小种群近交危害与集合种群上分析了竹类种质保护的适度思想,即适宜的局域种群与集合种群结构度是优化竹类野生种质保护的重要依据;并从区域相对封闭生态系统结构度与竹类种质稳定性上分析了野生种质适度保护的策略;最后从加强竹类种质种群生态学特征的编目清查、自然野生栖息地就地保护、竹类种质保存圃建立与完善,以及竹类原料林的定向培育4方面阐述了竹类种质的适度保护体系。     

Eugenol and thymol, alone or in combination, induce morphological alterations in the envelope of Candida albicans

The envelope of Candida albicans, with its outermost array of macromolecules protruding towards the environment, is pivotal to the expression of major virulence factors such as adhesiveness, and the morphological transition to hyphal form. We tested the anticandidal activity of eugenol, main component of clove oil, and thymol, main component of thyme oil, alone or in combination, by investigating their ability to interfere with the architecture of the envelope of C. albicans. Both molecules alterated the morphogenesis of the envelope, but the effects of thymol were more pronounced than those of eugenol. Certain combinations of the two molecules led to a synergistic effect, which is interesting in the view of potentiating their inhibition of C. albicans colonisation and infectiousness.     

Trees and shrubs as sources of fodder in Australia

Experience with browse plants in Australia is briefly reviewed in terms of their forage value to animals, their economic value to the landholder and their ecological contribution to landscape stability. Of the cultivated species only two have achieved any degree of commercial acceptance (Leucaena leucocephala and Chamaecytisus palmensis). Both of these are of sufficiently high forage value to be used as the sole source of feed during seasonal periods of nutritional shortage. Both are also leguminous shrubs that establish readily from seed. It is suggested that a limitation in their present use is the reliance on stands of single species which leaves these grazing systems vulnerable to disease and insects. Grazing systems so far developed for high production and persistence of cultivated species involve short periods of intense grazing followed by long periods of recovery. Similar management may be necessary in the arid and semi-arid rangelands where palatable browse species are in decline.     

Trade-Offs in Forest Utilization from a Sustainability Perspective

Abstract

A sustainable use of forests may be conceived of differently by different scientific disciplines. An underlying definition of sustainability is therefore central to the understanding of any analysis on the subject. This paper approaches the idea of sustainability from an economic perspective. The interpretation of sustainability in terms of concepts such as efficiency, equity and welfare are initially described. Empirical research aiming at obtaining basic elements of economic sustainability analyses is subsequently outlined. Finally, the implications for applied welfare and sustainability analysis at different economic and geographical levels of aggregation are discussed