新疆绿洲的沙漠化灾害及减灾措施

风沙灾害频发的季节是每年3～6月份。流动沙漠与绿洲直接毗邻的格局增加了下风方向绿洲风沙危害的态势。风沙灾害严重区有莫索湾绿洲,精河,艾比湖地区绿洲,喀什地区绿洲,和田地区绿洲,塔里木河下游绿洲。 新疆绿洲风沙灾害的发展趋势:绿洲外围及河流下游沙漠化土地在继续发展,风沙、尘埃天气显著增加;灌溉绿洲腹地特别是连片的大型绿洲风沙灾害显著减轻,6级以下起沙风基本上不造成风沙灾害;对于突发性,风速达8～9级以上的黑风尘暴,灾害仍不可避免。 采取的减灾措施:针对新疆许多河流下游断流,荒漠生态环境严重退化,沙漠化土地日益扩展蔓延的严峻局面,新疆已经着手进行主要河流的流域规划。塔里木河应急输水工程业已进入实施阶段;减轻对荒漠植被的压力,达到保护绿洲外荒漠植被的目的;加强大型防护林和农田防护林的建设;建立绿洲防止土地沙漠化、减轻风沙灾害的示范区和样板。新疆绿洲风沙灾害的根治仍然是任重道远。     

西北地区沙尘暴引发的荒漠化问题

从西北地区继1993～1995年连续3a出现沙尘暴之后，1996年甘肃和内蒙古西部的阿盟等地再次遭到沙尘暴的袭击入手，分析了沙尘暴发生的原因，指出它归根结底是荒漠化的直接后果。概述了荒漠化的状况及危害，并分析了其成因。     

Land resources potential and sustainable land management: an overview

Land degradation continues to be a major threat to local and national food security. With limited potential to develop new land, any increase in agricultural production must be sought largely through the better use of land already under cultivation. Concerns for the global environment associated with agriculture worldwide have also increased in recent years and require more coordinated efforts at global and national levels with decentralisation of activities at the local level.
This article presents an overview of land resources potential for food production, the processes and extent of land degradation and its economic and environmental costs and impacts, and highlights some macro-economic policies and institutional measures for the prevention of land degradation and rehabilitation of degraded lands. A people-centred programme is presented as a basis for decentralising activities for sustainable land use and land management. Finally, the need for better coordinated efforts of concerned UN, multinational agencies and NGOs for the implementation of Agenda 21 and related conventions is stressed.     

Diurnal and spatial variations of soil NOx fluxes in the northern steppe of China

NOx emissions from biogenic sources in soils play a significant role in the gaseous loss of soil nitrogen and consequent changes in tropospheric chemistry. In order to investigate the characteristics of NOx fluxes and factors influencing these fluxes in degraded sandy grasslands in northern China, diurnal and spatial variations of NOx fluxes were measured in situ. A dynamic flux chamber method was used at eight sites with various vegetation coverages and soil types in the northern steppe of China in the summer season of 2010. Fluxes of NOx from soils with plant covers were generally higher than those in the corresponding bare vegetation-free soils, indicating that the canopy plays an important role in the exchange of NOx between soil and air. The fluxes of NOx increased in the daytime, and decreased during the nighttime, with peak emissions occurring between 12:00 and 14:00. The results of multiple linear regression analysis indicated that the diurnal variation of NOx fluxes was positively correlated with soil temperature (P < 0.05) and negatively with soil moisture content (P < 0.05). Based on measurement over a season, the overall variation in NOx flux was lower than that of soil nitrogen contents, suggesting that the gaseous loss of N from the grasslands of northern China was not a significant contributor to the high C/N in the northern steppe of China. The concentration of NOx emitted from soils in the region did not exceed the 1-hr National Ambient Air Quality Standard (0.25 mg/m³).     

中国黄土高原地区的风蚀灾害及其防治

对我国黄土高原地区的风蚀情况及其严重危害作了简要阐述，指出坚持实施水土保持综合治理是防治风蚀灾害的根本途径，并对防治工作对策提出若干建议．     

东川市土地退化（荒漠化）及其防治

分析了东川市土地退化现状：土地退化以水蚀为主,退化土地面积占总土地面积38．5％。土地退化类型主要有土壤退化、土地沙石化、土地石质化和侵蚀劣地。文章还探讨了东川市土地退化的原因,提出了土地退化防治对策。     

Potentials for Combating Desertification in Hunshandak Sandland Through Nature Reserve

Desertification directly threatens more than 250 million people and one third of the earths land surface. Although it is well known that desertification could be reversed in most cases if the intensity of land use were reduced, there have been no studies on how to achieve this reversed desertification on a large scale. We conducted a case study in Hunshandak Sandland of North China, exploring how creation of a nature reserve might aid restoration of a degraded ecosystem. Experimental data indicated that desertified regions, if designated as a nature reserve, could be restored with conservation of biodiversity. The buffer zones in moderately desertified lands could serve as a base for forage production and/or ecotourism industry. The construction of ecologically designed towns (ecotowns) in transition zones could accommodate migrants moved from core zones so as to develop stock production, related industry, and ecotourism, enabling both economic and environmental development. Up to now, 5778 local inhabitants in the core zones of Zhenglan Banner (county) in the Hunshandak Sandland have been moved out of the severely degraded areas with the financial assistance of the central government. Those people have been moved into three eco-towns of the Banner with an objective of greatly enhancing the economic and social status while restoring the degraded sandlands.     

Retaining natural vegetation to safeguard biodiversity and humanity

Global efforts to deliver internationally agreed goals to reduce carbon emissions, halt biodiversity loss, and retain essential ecosystem services have been poorly integrated. These goals rely in part on preserving natural (e.g., native, largely unmodified) and seminatural (e.g., low intensity or sustainable human use) forests, woodlands, and grasslands. To show how to unify these goals, we empirically derived spatially explicit, quantitative, area-based targets for the retention of natural and seminatural (e.g., native) terrestrial vegetation worldwide. We used a 250-m-resolution map of natural and seminatural vegetation cover and, from this, selected areas identified under different international agreements as being important for achieving global biodiversity, carbon, soil, and water targets. At least 67 million km² of Earth's terrestrial vegetation (∼79% of the area of vegetation remaining) required retention to contribute to biodiversity, climate, soil, and freshwater conservation objectives under 4 United Nations’ resolutions. This equates to retaining natural and seminatural vegetation across at least 50% of the total terrestrial (excluding Antarctica) surface of Earth. Retention efforts could contribute to multiple goals simultaneously, especially where natural and seminatural vegetation can be managed to achieve cobenefits for biodiversity, carbon storage, and ecosystem service provision. Such management can and should co-occur and be driven by people who live in and rely on places where natural and sustainably managed vegetation remains in situ and must be complemented by restoration and appropriate management of more human-modified environments if global goals are to be realized.     

荒漠化类型划分及其数量化评价体系

从我国荒漠化监测的实际需要出发，提出了包括气候区、外营力、土地利用类型、地表特征和荒漠化程度在内的多因素复叠式荒漠化分类体系；既可适用于小区域大比例尺的重点监测，又可适用于大区域小比例尺的宏观监测的各荒漠化类型数量化程度判定指标体系和判定方法；适用于各级行政区的荒漠化水平评价方法．     

A general assessment of the environmental impact of refugees in Somalia with attention to the refugee agricultural programme

This paper attempts to examine the broad features of Somalia's harsh physical environment into which several hundreds of thousands of refugees, with mainly a nomadic or semi-nomadic life style and culture, dramatically descended six years ago. The thirty-six rural camps in which at least half of them live are described as is the refugee agricultural programme which is training several thousand families so that they may be "self-supporting." The four regions where the camps are located are each briefly summarized in terms of their soils, their climates, their natural vegetation, and the type of agriculture which the refugee farmers practice. A more detailed analysis is then given on the following critical environmental concerns: Vegetation and erosion on refugee farms, the growing problem of refugee livestock, the destruction of trees, and irrigation practices and salinity on refugee farms. The paper concludes with an argument to preserve Somalia's environment from careless and destructive exploitation, which is leading towards desertification, and calls for an in-depth study of the situation.