Land Degradation Problems and Their Implications for Food Shortage in South Wello, Ethiopia

/ Understanding the problems of land degradation and seeking long-lasting solutions to these problems should be one of the central concerns of countries such as Ethiopia where agriculture is the mainstay of no less than 85% of the population. To this end, the collaboration of policy makers, researchers, donor agencies, and the local people is indispensable. In this paper an attempt is made to discuss the causes of land degradation and the reasons for the failure in the endeavors made to solve the problems. Possible solutions, which may help to ameliorate the situation, are also suggested. The study deals with South Wello (a region in northern Ethiopia), but the assessment is, by and large, a reflection of most of the highlands in the country. KEY WORDS: Agroforestry; Donor agencies; Food for work; Hillside closures; Land rehabilitation; Local participation; Population growth; Reforestation     

Environmental policy indicators: A systems model

This article describes and tests a systems theory-based policy indicators model. The framework is used to examine propositions about linkages between states' ecological-spatial characteristics and subsequent selected solid waste management (SWM) -related environmental policies. It was hypothesized that state characteristics of: (1) population density (used as a garbage-per-land area index), (2) population convergence within urban areas, and (3) percent population change in the interval 1980–1985, could jointly explain state variation in both the number and the vigor of SWM policy outputs. Greater levels of spatial pressure were proposed to be related directly to more numerous, more convincing policies. Proposals are grounded in the literature of organizational search theory, crisis stimulation, and technological pressure. Results revealed that the sociospatial model in fact could explain a reasonable proportion of policy variation across states. However, not all hypotheses are supported. Population change shows an indirect, rather than the anticipated direct, relationship with policy output levels. In addition, when used in the model as a pollution intensity index, population density failed to contribute significantly to an explanation of differences in state SWM policy levels. The analysis raises questions about changes occurring over time in the nature and direction of linkages between sociospatial measures and policy responses. This study suggests that strengthening policy indicator models may require questioning key assumptions and theoretical bases, conducting longitudinal studies, and factoring in political, economic, and other policy environment forces.     

Toxicity studies and environmental impact assessment

There is abundant evidence that many factors can influence the toxicity of a particular pollutant including environmental fluctuations, season of the year, stage in life cycle, size, and sex. All of these factors should be assessed before making a judgment of the effect on natural populations. Such an assessment can be conceptualized using a simple population model through whichcontrol gates operate as functions of 1). the direct self-maintainance feedback from existing adult population biomass and 2). the recruitment of new individuals due to the maturation of larvae. By extracting general principles of organismic response to pollutants it is possible to incorporate the information into large-scale ecosystem models which would serve as working tools for answering environmental decision-making problems.     

油田联合站沉降罐小呼吸损耗核算

利用美国石油协会(API)小呼吸损耗核算新公式对国内某油田4个联合站的采出液沉降罐进行了小呼吸损耗核算,并与实测数据进行了对比分析。分析结果表明,API的核算值与实测值的差别较大,相对误差可达90%以上,原因是国内油田采出液沉降罐的现场工况与API公式的模拟条件差别较大。在数据分析的基础上引入平均液体表面温度和平均气体流速两个影响因子对上述公式进行了修正,并利用修正后的公式对另外两个联合站的沉降罐进行了小呼吸损耗核算,核算结果的相对误差降至10%以下。     

The role of population projections in environmental management

California and other regions in the United States are becoming more populated and ethnically diverse, and thus, ecological impacts on the wildland–urban interface are a significant policy concern. In a socioeconomic assessment focused on the geographic regions surrounding four national forests in southern California, population projections are being formulated to assist in the update of forest plans. In southern California, the projected trend of explosive population growth combined with increased ethnic and racial diversity indicates four challenges for environmental management. First, patterns of recreation use on wildlands are likely to change, and management of these areas will have to address new needs. Second, as land-management agencies face changing constituencies, new methods of soliciting public involvement from ethnic and racial groups will be necessary. Third, growth in the region is likely to encroach upon wildland areas, affecting water, air, open space, and endangered species. Fourth, in order to address all these concerns in a climate of declining budgets, resource management agencies need to strengthen collaborative relationships with other agencies in the region. How environmental managers approach these changes has widespread implications for the ecological sustainability of forests in southern California.     

都市扩张与土地资源利用集约化：关于上海市城市发展模式的研究

随着我国经济的持续高速增长,人口向城市,尤其是大城市集中的趋势越来越明显,城市规模正在迅速膨胀。具体说来,主要体现在以下三个方面－城市占地面积的扩张;城市人口的膨胀;城市经济实力的增长。     

Effects of Tracking by Armored Vehicles on Townsend's Ground Squirrels in the Orchard Training Area, Idaho, USA

Spermophilus townsendii ) prey. These changes could occur directly or as a result of changes in the vegetation available as food and cover for the ground squirrels. We assessed the effects of long-term tracking by armored vehicles by comparing 9-ha areas in sagebrush (Artemisia tridentata) -dominated shrubsteppe and bluegrass (Poa secunda) -dominated grasslands subjected to low-intensity tracking for ∼50 years with others that had not been tracked. We did not detect any effect on ground squirrel population dynamics associated with long-term tracking. Although densities of adults and juveniles tended to be higher in the areas exposed to such tracking, we attribute this difference to other factors that varied spatially. To determine short-term (two-year) effects, we experimentally tracked two sagebrush and two grassland sites with an M-1 tank after animals had begun their inactive season. In the following two active seasons we monitored squirrel demography and behavior and vegetative characteristics on the experimentally tracked sites and compared the results with control sites. Although we experimentally tracked ∼33% of the surface of each of four sites where ground squirrel densities were assessed, the tracking had a detectable effect only on some herbaceous perennials and did not influence ground squirrel densities or behavior significantly during the subsequent two active seasons. We conclude that tracking after the start of the inactive season is likely to influence ground squirrel demography or behavior only if vegetation cover is substantially changed by decreasing coverage of preferred food plants or increasing the coverage of annual grasses and forbs that are succulent for only a short time each year.     

热分层油品中气泡浮升动态过程的数值实验

本文应用数值分析方法研究热分层油品中气泡浮升运动的动态过程。同时，分析气泡在热分层油品中上升时引起的气泡长大及气泡振荡现象，得到了物理趋势合理的结果。     

跨世纪人口压力对中国生态环境的影响及对策

人口是人口，资源与环境系统中最根本的主导因素，人口增长过快，将直接加大对资源与环境的压力，并影响人口素质的提高，根据我国人口庞大的基数，过快的增长速度，独特的人口结构和较低的文化素质现状，对生态环境造成的压力进行了系统分析，进而提出了控制人口增长，改善生态环境和全面发展国发经济的对策，以保证跨世纪人口，资源，环境呈现协调，持续，健康的发展趋势。     

液化石油气管线波纹补偿器爆裂事故分析

波纹补偿器爆裂事故，经济损失严重。用事故树方法进行定性分析，找出发生事故的主要原因，从安全设施、生产管理、安全管理方面采取防范措施，防止事故的重复发生。