甘家湖荒漠林区生态恢复工程的影响因素及其环境效益评价

主要从生态恢复方面对甘家湖荒漠林区的恢复措施及其所产生的环境效益、社会效益及综合效应进行论证，分析甘家湖荒漠林区目前的状况及采取恢复措施后所能达到的效果。     

综合治理沙漠化灾害

本文对我国沙漠化灾害有自然和人为的两方面原因，进行了具体的分析和介绍。     

从地气耦合角度讨论沙漠的成因

沙漠的成因是干燥气候和强大风力的产物.中国的大沙漠多在地壳运动相对稳定的地区,如塔里木地区、准噶尔地区、阿拉善地区、鄂尔多斯地区以及内蒙古东部地区等,因此可以认为,可能还有地下因素参与了沙漠的形成.其形成机制可能是:地壳运动稳定地区地下的携热水汽或其他携带热量的气体不易逸出,这样就不易在稳定地区大气中造成低气压状态,因而不易吸引冷热气团来交会降雨以及不易形成水汽的垂直对流降雨,这些后果叠加在更大范围的气候干燥背景上,使这些地区更加干旱,于是形成大沙漠.这种沙漠的扩展又在一些原来不是沙漠的农业区形成沙漠或沙地.     

Past desertification processes of Minqin Oasis in arid China

Irrigated farming has affected most natural oases in western China since the Han Dynasty employed advanced agricultural techniques in dryland areas. To date, little is documented about the process through which these oases were modified by human systems. In this study, a multi-disciplinary approach incorporating analysis of historical documents, archaeological field surveys, satellite imagery, and GIS data was used to understand desertification processes in the Minqin Basin in Gansu Province, China, over the historical period. Results suggest that initial reclamation efforts around the Minqin Oasis were launched in the Han Dynasty (220–121 BC) and culminated in the Wei and Jin Dynasty (220–420). During the following 800 years from the Southern and Northern Dynasties (420–581) to the Yuan Dynasty (1271–1368), farmland disappeared and became desert when the region was taken over by nomadic people. The second period of intense development occurred in the Ming Dynasty (1368–1644) and was followed by another more aggressive development in the Qing Dynasty (1644–1911), which resulted in the largest reclaimed area in history. Oases were constantly reclaimed and subsequently abandoned and desertified over the whole historical period. The causes were complex, but the major cause was related to dynastic transition that often resulted in changes in national policies.     

沙漠地区沙尘气溶胶含量变化的原因分析

利用中国大陆气溶胶指数(TOMS AI)、太阳辐射、沙尘能见度、降水量等观测资料,对中国西北部沙漠地区沙尘气溶胶含量进行分析.结果表明,沙漠地区AI值不但取决于沙尘暴的发生,而且取决于太阳辐射.这表明沙尘暴起沙模型和尘卷风与干热对流的联合起沙模型互为补充,沙漠地区上空的沙尘气溶胶含量是它们共同作用的结果,而由太阳辐射引发的尘卷风与干热对流较沙尘暴过程更为重要.     

荒漠能源植物气化发电的环境影响评价

对荒漠生物质气化发电进行LCA评价,建立评价模型,在评价过程中选用了燃煤发电系统为参照.研究结果表明,生物质利用过程没有CO2的排放,整个发电周期中仅原料的生产、运输以及预处理过程消耗能量导致CO2排放,因此生物质气化发电方案的排放量远远小于燃煤方案,减排量达到了87%-94%.生物质发电与燃煤发电相比,对环境污染降低程度的总指数为3.68.生物质能源的开发大大削减了化石能源利用带来的环境污染问题,同时也能够缓解能源危机.     

荒漠化对新疆绿洲生态环境的危害

新疆荒漠化土地面积大,分布范围广,发展程度高,危害严重.目前,新疆的荒漠化面积为104.4×104km2,占全区总面积的65.25%.在自然因素和人为因素叠加影响下,新疆的荒漠化越来越严重威胁到绿洲生态环境.近几十年来,新疆过度开垦和人口增长过快已经给原本脆弱的生态环境带来巨大压力,加剧了水资源的耗用和土地荒漠化的进程.因此,防治荒漠化,是实现荒漠地区人口,资源与环境协调发展的根本途径.本文简要论述新疆日趋严重的荒漠化对绿洲生态环境的危害.并提出防治对策和见解.     

Association between plant species diversity and edaphic factors in the lower reaches of the Heihe River,northwestern China

The lower reaches of the Heihe River, in northwestern China, is characterised by unique local edaphic conditions that have influenced the development of local desert riparian forests. This study examines the variations in spatial variation patterns to reveal the relationships between plant species diversity and soil moisture/salinity/texture gradients at different soil depths, providing insights into the management and restoration of vegetation in ecosystems in the study area. The species–environmental relationships are investigated by redundancy analysis based on the plant species diversity matrix and the edaphic gradient matrix. A survey of 61 sampling plots identified 37 plant species in the study area. The distribution pattern of the plant species diversity are mainly affected by soil moisture, soil salinity, and soil texture at different soil depths. These edaphic factors are able to explain 98.47% of the total variation in the analysed vegetation dataset. Soil moisture, salinity, and texture content vary in terms of both the soil depths and the vegetation types in the study area. The plant community Class IV, xeric shrub, has the lowest soil water content among different vegetation types. The surface soil salinity differs for different plants and follows the order: Sophora alopecurides?>?Tamarix chinensis?>?Populus euphratica.     

Changes in desert steppe soil culturable bacteria from northwestern China and correlation with physicochemical parameters

Seasonal variations effects on desert steppe soil culturable bacteria in northwestern China and physicochemical parameters were investigated. Soil temperature ranged from 5.37 to 23.73 °C. Moisture content varied from 3.22% to 7.62%. The pH was between 7.98 and 8.72. Soil nutrients were altered in different seasons. Total potassium (K) remained the same, but available K levels ranged from 101.29 to 227.55 mg/kg. The culturable bacterial counts in January, April, July and October were 0.13 × 10⁷, 4.09 × 10⁷, 5.33 × 10⁷ and 1.8 × 10⁷ colony forming units (cfu)/g, respectively. Bacterial populations were most abundant in surface layers and declined with increase of soil depth. Seventy-two bacterial strains were isolated and classified according to 27 genera of 5 phyla groups: Firmicutes, Actinobacteria, Alphaproteobacteria, Gammaproteobacteria and Bacteroidates. The bacterial diversities varied according to seasons. In spring, only Firmicutes and Actinobacteria were isolated. In summer, Firmicutes, Actinobacteria and Bacteroidetes were detected with Firmicutes the dominant species. In autumn and winter, Firmicutes, Actinobacteria, α-Proteobacteria and γ-Proteobacteria predominated. Our results indicated that climatic variations, vegetation coverage and soil physicochemical parameters are critical factors for maintaining culturable bacterial populations and diversity in the desert steppe. Soil moisture content and temperature exerted marked influence on bacterial quantities and diversities.     

沙尘暴的成因与防治措施初探

针对今春我国北方地工百北京连续７次的扬尘和沙尘暴龙击,分析其成因及危害,提出了防治沙尘暴的具体措施及建议,为沙尘暴的有效治理提供一定的科学依据和参考。