干旱区极端环境下营造固沙林的探讨

干旱区环境极端恶劣,近年来,由于人为干扰,荒漠化面积扩大,使本以脆弱的生态系统逆向发展,给人们生活带来影响。因此,目前防沙治沙已成为一件意义重大而又十分艰巨的任务。其中,林业的建设有不可替代的作用,在固沙林营造过程中,要因地制宜,切合实际,选择适宜的树种,合理的搭配,以水为平衡中心,确定适当的种植密度,建立一个完善的固沙林体系。本文着重讨论固沙林营造的措施。     

陕北风沙滩地区土地退化机理及治理对策

本文在分析研究区环境背景的基础上,运用定性与定量相结合的方法,对土地退化的发生机制、时空规律和发展趋势进行了系统研究。并以景观生态学理论和可持续发展思想为指导,提出了对退化性土地进行有效整治和生态重建的技术措施与对策。     

东胜矿区沙漠化土地治理技术

通过对东胜矿区的流动沙丘设置油蒿沙障、乔灌造林和围封管护的技术方法,治理井田强度沙漠化面积65.94km~2,初步遏制住了目前100km~2开发建设区域的沙漠化危害,已获得显著的生态环境效益。     

呼伦贝尔沙化草地不同生态修复阶段植物群落特征研究

人工植被修复是减缓草地沙化与生态重建的重要措施,理解不同修复阶段的沙地植物群落演替特征及其影响因素有利于沙地植被的持续修复。以呼伦贝尔市甘珠尔沙地植被修复为例,分别调查了修复9、11、13、15 a共4个不同修复阶段植物群落结构特征及土壤理化性质,探索甘珠尔沙地人工修复植物群落演替变化及其对环境因子的响应。结果表明：研究区共发现植物42种,隶属于17科35属。草本39种,以菊科、禾本科、蔷薇科和豆科为主;灌木3种,为豆科和菊科。不同修复年限物种数变化依次表现为28种（15 a）、25种（13 a）、19种（9 a）和16种（11 a）。各年限内多年生草本物种数均明显高于一年生和一/二年生植物。草本与灌木在不同修复阶段其优势种、地上生物量及物种多样性均存在波动变化,具体表现为草本植物中地梢瓜(Cynanchum thesioides)、虫实(Corispermum hyssopifolium)、披碱草(Elymus dahuricus)、糙隐子草(Cleistogenes squarrosa)、羊草(Leymus chinensis)与狗尾草(Setaria viridis)的优势度较高,灌木以小叶锦鸡儿(Caragana microphylla)为主要优势种。草本植物地上生物量和总盖度整体呈现波动增加的趋势但差异不显著。灌木总盖度15 a显著高于9 a,地上生物量整体呈现逐渐增加的趋势,表现为11、13、15 a均显著高于9 a。不同修复阶段的物种多样性指数在草本中无显著差异,但在灌木层表现为15 a显著高于9 a。随机森林模型表明,沙化草地的修复过程中气候及土壤因子对植物群落结构特征贡献度存在差异。土壤总氮含量、总钾含量、有机质含量、年降水量和年均风速是影响甘珠尔沙地草本植物多样性的主导因子,其中除年均风速外均为正相关。因此,建议在沙地植被修复中适当增加含氮、钾、有机质等营养物质的肥料,促进沙化生态系统的植物群落结构重建与多样性的恢复。

     

Trichloroacetic Acid as Additional Factor Contributing to Desertification in Southern Africa

There has been an accelerated expansion of deserts in the past five decades. Recent data reveal that the atmogenically formed organic compound, trichloroacetic acid (TCA) is a contributory factor in addition to anthropogenic and natural sources. The aim of this study was to use TCA as an indicator for the possible occurrence of C₂-chloroacetic acids; to assess the burden on the vegetation by using pine needles as a bio-indicator system and to deliberate on the possible role of TCA in the dynamics of the vegetation in southern Africa. Field experiments conducted on pine trees and on C₃ and C₄ crop plants under controlled laboratory conditions, have revealed that plants could be influenced positively or negatively by TCA. To obtain an integrated assessment of the pollution emission over a time span of at least one year, two-year-old pine needles of different Pinus species were used as a bio-indicator for TCA pollution at different measuring sites. The data of our investigation clearly indicate that areas exist in South Africa where the vegetation is burdened by ecotoxicologically relevant TCA contents comparable to those in central Europe and southern Russia where TCA was shown to play a role in the destabilisation of the steppe vegetation.     

Prospects and Constraints of Desert Agriculture: Lessons from West Omdurman

Sudan is the largest country in Africa with an area of about 2.5 million km²; the country hosts a population of about 31 million people. About two-thirds of the country area is located within arid and semi-arid regions. Recently, especially during the last half of the previous century, these regions were subject to various forms of land degradation. This paper discusses the general prospects and constraints of desert agriculture. It also presents a detailed case study of West Omdurman, which is located in a semi-desert climatic zone. The ambitious plans to utilise the area for agricultural production were initiated because of the relatively fertile soil, availability of water and the proximity of the area to marketing and export centres. The paper discusses the different land use systems experienced in the area, reasons for failure are identified and possible remedies discussed. In addition, constraints facing the proposed West Omdurman Canal Project are also discussed. Finally, the paper reviews the major research findings of Rawakeeb Dryland Research Center with regard to promoting agricultural productivity.     

Applied research of landscape ecology in desertification monitoring and assessment

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Desertification,and climate change: the case for greater convergence

Poor knowledge of links between desertification and globalclimate change is limiting funding from the Global Environment Facility foranti-desertification projects and realization of synergies between theConvention to Combat Desertification (CCD) and the FrameworkConvention on Climate Change (FCCC). Greater convergence betweenresearch in the two fields could overcome these limitations, improve ourknowledge of desertification, and benefit four areas of global climate changestudies: mitigation assessment; accounting for land cover change in thecarbon budget; land surface-atmosphere interactions; and climate changeimpact forecasting. Convergence would be assisted if desertification weretreated more as a special case in dry areas of the global process of landdegradation, and stimulated by: (a) closer cooperation between the FCCCand CCD; (b) better informal networking between desertification and globalclimate change scientists, e.g. within the framework of theIntergovernmental Panel on Climate Change (IPCC). Both strategies wouldbe facilitated if the FCCC and CCD requested the IPCC to provide ascientific framework for realizing the synergies between them.     

人类面对荒漠化的问题应采取的对策

荒漠化是当今重大的全球性环境问题,困扰着人类社会的生存和发展,针对这一长期 存在的问题,提出了一些人类面对荒漠化的对策。     

沙尘暴成因及人文思考

沙尘暴是我国西北和华北地区经常发生的灾害性天气.沙尘暴对国民经济造成了巨大损失,制约了我国西部大开发战略的实施.在分析沙尘暴危害和成因的基础上,提出了重点从人口、法律制度和产业结构等方面治理沙尘暴.