The relationships of population and forest trends

The relationship between national trends in forest area and population is reviewed at the global scale. Evidence of an inverse relationship is confirmed. The relationship, however, may have weakened in recent decades, and it has clearly undergone a reversal in some countries during the nineteenth to twentieth centuries. The theme of a changing relationship through time is thus developed, as is that of an asymmetrical relationship in the sense that the forest area is likely to stabilize before population. On the basis of modelling from the current demographic relationship, the global forest area should stabilize before the middle of the twenty-first century.     

Stress resistance strategy in an arid land shrub: interactions between developmental instability and fractal dimension

This paper investigates allocation of energy to mechanisms that generate and preserve architectural forms (i.e. developmental stability, complexity of branching patterns) and productivity (growth and reproduction) in response to environmental disturbances (i.e. grazing and resource availability). The statistical error in translational symmetry was used to detect random intra-individual variability during development. This can be thought of as a measure of developmental instability caused by stress. Additionally, we use changes in fractal complexity and shoot distribution of branch structures as an alternate indicator of stress. These methods were applied to Anthyllis cytisoides L., a semi-arid environment shrub, to ascertain the effect of grazing and slope exposure on developmental traits in a 2×2 factorial design. The results show that A. cytisoides maintains developmental stability at the expense of productivity. Anthyllis cytisoides was developmentally more stable when grazed and when on south-facing, as opposed to north-facing slopes. On the contrary, shoot length, leaf area, fractal dimension and reproductive-to-vegetative allocation ratio were larger in north- than in south-facing slopes. As a consequence, under extreme xeric conditions, shrub mortality increased in north-facing slopes, especially when not grazed. The removal of transpiring area and the reduction of plant competition favoured developmental stability and survival in grazed plants. Differences between grazed and ungrazed plants were most evident in more mesic (north-facing) areas.     

Applying the Political Geography of Scale: Grassroots Strategies and Environmental Justice

The grassroots environmental movement often protests locally unwanted land uses. Many grassroots groups have, however, expanded their agenda to the scale of environmental justice. Explanations for this scale transformation include historical circumstances, individuals' radicalization through activism, and the growth of environmental justice networks. This case study, grassroots environmentalists' opposition to a proposed electricity transmission line in Monroe County, WV, explores another explanation: appeals for environmental justice are also a strategic response to siting regulatory procedures. With concepts emerging from the political geography of scale, I interpret the Monroe Countians' efforts and show how their strategies link the grassroots scale with that of environmental justice.     

铅对日本沼虾精子超微结构的影响

用铅 ( Pb2 + )溶液的 72 h半致死浓度处理日本沼虾 ,发现日本沼虾的精子结构受到严重破坏。主要表现在精子顶体的解体、顶体及核物质的大量丢失以及精核形态的变化上 ,这种类型的精子失去了正常受精的能力 ,直接导致个体的不育 ,使自然种群繁殖率下降。虾蟹类精子结构的变化可以作为监测环境污染的重要形态学指标。     

拉萨城市用地变化分析

根据１９９９年８～８月实地调查和以往文献资料、４期航片和地形在信息,动用遥感信息解译和ＧＩＳ软件分析及ＧＰＳ定位核查,准确地展现了过去５０年中拉萨城市用地变化进程,重点分析了城市用地变化产生的生态与环境和问题。主要结论如下：①拉萨城区拓展迅速,从１９５１年始到１９９９年,城区扩大了１０．３１倍,城市建设面积扩大了近１９倍。城区发展分为：城市扩建初期（１９５２～１９６５年）、高速发展时期（１９６６～     

中国农村资源,环境与发展的可持续性评估：SEEA方法及其应用

基于一体化核算体系（Ｓｙｓｔｅｍ ｏｆ Ｅｎｖｉｒｏｎｍｅｎｔａｌ－Ｅｃｏｎｏｍｉｃ Ａｃｃｏｕｎｔｉｎｇ简写为ＳＥＥＡ）分析１９９０￣１９９６年间中国农村的资源净产值、环境净产值和真实储蓄。表明中国农村经济发展的资源与环境代价巨大。资源净产值每年损失幅度为２１￣１４２６亿元,平均占农村总产值的１．７２％;环境净产值每年损失幅度为６０４￣１０５９亿元,平均占农村总产值的２．３３％;真实储蓄在－１２     

The causes of low-temperature demagnetization of remanence in multidomain magnetite

In this paper, the mechanisms of low-temperature demagnetization of remanence in multidomain magnetite are considered. New experimental observations of the behaviour of the saturation isothermal remanence, thermoremanence and partial thermoremanence at low temperatures are presented. The results show that there are two main contributions to this low-temperature demagnetization. The first and predominant contribution (type-1 demagnetization) is due to 'kinematic' domain state reorganization and occurs throughout cooling from room temperature to the Verwey transition, T _v , at 120–124  K. The second contribution arises from the change in anisotropy from cubic to monoclinic at T _v , which changes the overall domain structure of the grain. On warming in zero field, some domain walls will not return to their original positions but will take up a position that leads to a lower net remanence (type-2 demagnetization). In stoichiometric magnetite, demagnetization does not occur at 130  K at the isotropic point, T _k , contrary to some previous predictions. In non-stoichiometric magnetite, the influence of the Verwey transition is greatly reduced, and anomalous behaviour is observed at T _k .     

可持续发展代际公平的初步研究

可持续发展概念自诞生以来,已经越来越得到社会各界的关注,其基本思想已经被国际社会广泛接受,并逐步向社会经济的各个领域渗透,成为当今社会的热点问题之一。按照国际社会广泛接受的概念,可持续发展是指既满足当代人的需要,又不损害后代人满足需要的能力的发展。显然,这里就提出了一个代际之间的关系问题。文章初步研究了可持续发展与环境冲突问题及代际公平的解决。     

浙江省萧山北部地区农业地质环境调查成果

萧山北部地区农业地质环境调查从氮磷钾的合理配比和微量元素合理施用方面为农业生产科学施肥提供了科学的依据 ;从制定农田耕作层的保护措施 ,控制化肥施用 ,实行平衡施施肥 ,降低农田灌溉水的污染 ,充分发挥肥效等方面 ,提出了保护土地资源、实施“沃土计划” ;根据农业地质的基础资料进行了农业环境保护区划 ,将本区划分为沿江陆域岸线保护带、萧山南沙大堤保护带和农业环境保护区 ;并提出要加强钱塘江海堤建设 ,防治地质灾害的发生     

Pollution trend in the tumen river and its influence on regional development

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