沙漠化

Topic sentence 1: The area of desert in the world is growing every year.

主题句子1：每年世界上沙漠化的土地面积都在不断地增长。

The sandy desertified lands have the tropical coastal dene c haracteristics in the district, the shape, the xerophyte and the rapid evolvemen t of land use.

海南岛西部沙漠化土地具有热带海岸沙地的地域特征、形态特征、旱生植被景观特征和土地利用快速演变特征。

The two causes are related to natural and anthropogenic factors.

沙漠化的形成有自然和人为两方面原因。

ABSTRACT This dissertation, based on the theories of geography, ecology, economics, sociology and environmental sciences, has analyzed the impact of transition between cultivation and pasture animal husbandry on the mechanism of desertification in Kerqin Sandy Region, of which behavior mechanism of local people was emphasized. The changing direction of integrated land desertification control strategy in semi-arid regions was discussed after having explored the primary reasons of estrepement, overgrazing and excessive firewood gathering. Followings are the main research works having been done.

本文选取科尔沁沙地作为研究区域，以两种最主要的土地利用方式、也是两种最主要的生产方式——农、牧业作为研究对象，依据地理学、生态学、经济学、社会学与环境科学的基本理论与方法，基于现有研究资料的系统整合，结合野外调查的结果，从更加综合的角度，来研究农、牧业选择变化对沙漠化过程的影响机理，从农、牧业选择变化的角度来揭示&滥垦、滥牧、滥樵&的本质，进而寻求中国北方半干旱地区生态环境综合整治的对策。

As a result, the desertification intensification in the headwater area of the Yellow River is resulted from physical and socioeconomic factors.

黄河源区以超载过牧为主的土地资源的过度利用以及由此造成的鼠害泛滥，人为造成了广大范围草地退化、风沙活动强度的增强，从而导致人为沙漠化过程的发生与发展。

Based on spatial pattern of physical environment and socioeconomic status, the causes of desertification in the headwater area of the Yellow River are discussed using geographical information system and remote sensing.

根据黄河源区的自然环境条件、社会经济发展状况，在GIS的支持下对沙漠化发生发展的物质条件、气候条件以及人类活动等影响因子的空间格局特征、规律和变化趋势进行了定量分析。

It can provide some theoretic gist for resource value of water and soil in sandy land to indicate the change and law of soil moisture character, as well as the water circulation and balance mechanism in sandy land, at the same time, it have important practical significance to protect limited water resource, improve using efficiency of water resource,control desertification, choose and educate sand binding plant, renew and restore degraded ecosystem, as well as the economy benefit of irrigative agriculture and intending trend of development.

揭示沙地土壤水分特征的变化规律以及沙地水循环和平衡机理，可以为沙地水土资源评价提供一定的理论依据，同时对于保护当地有限的水资源和提高水资源的利用效率，以及沙漠化防治，固沙植物的选育，退化生态系统的恢复与重建，灌溉农业的经济效益和未来的发展趋势都具有重要的实践意义。

Three seriousenvironment problems of the soil erosion, desertification and salinization in the aridand semiarid area not only endanger the throughput and the stability of the dry landfarming, but also jeopard the country ecosystem security.

干旱、半干旱地区的水土流失、土地沙漠化、土壤盐碱化三大环境问题，不仅直接危害北方旱地农业系统的生产能力和稳定性，而且危及到了国家生态安全建设。

Most species' populations were decline in last fifty years, especially since the last 1980's, the populations such as Alpine Musk Deer, Przewalski's Gazelle and Red Deer etc. declined dramatically;(5) Desertification and grassland degredation are obviously affected by climate change on macrographic scale, anthropogenic activities is an important driving role for desertification, herbing, land-development and urbanization have majority impact to biodiversity spatial pattern and its loss.

祁连山区动物资源组成成分复杂，总体上缺乏自身特有的种类，哺乳动物区系特点不很突出，既包含了东部黄土高原和东南湿润地区的兽类成分，又不乏青藏高原特有种类，同时还与新疆的动物区系有一定的联系，近50年来尤其自上个世纪80年代以来，多数种类的种群数量呈下降趋势，其中以马麝、普氏原羚、马鹿等物种的数量下降的最为显著；（5）土地沙漠化和草地退化在宏观尺度上受气候因素影响较大，人类活动对荒漠化的加速发展起着重要的驱动作用，尤其是放牧、土地开发和城镇化建设对生物多样性资源减少以及空间分布格局影响较大。

It has become a hot topic of palaeoclimatic and palaeoenvironmental studies, so till now there have been many research achievements about it.

近年来，全球气候环境不断恶化，例如全球变暖、臭氧空洞的出现、沙漠化加快扩展、生物多样性的减少等。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。