The extent of desertification on Saudi Arabia   总被引：2，自引：0，他引：2  

Ammar?A.?AminEmail author 《Environmental Geology》2004,46(1):22-31

Desertification is the process that turns productive deserts into non-productive deserts as a result of poor land-management. Desertification reduces the ability of land to support life, affecting wild species, domestic animals, agricultural crops and humans. The reduction in plant cover that accompanies desertification leads to accelerated soil erosion by wind and water. South Africa is losing approximately 300–400 million tons of topsoil every year. As vegetation cover and soil layer are reduced, rain fall impact and run-off increases. This paper discusses the extent of desertification, its potential threat to sustained irrigated agriculture and possible measures adopted to control ongoing desertification processes to minimize the loss of agricultural productivity in an arid country such as the Kingdom of Saudi Arabia.  相似文献   

图形分形理论在沙漠化定量研究中的应用   总被引：27，自引：3，他引：24  

赵永平  王一谋 《中国沙漠》1995,15(2):175-180

以Mandelbrot的分形理论为基础,较详细地推算了图形面积与周长的分数维公式,并以农牧交错带典型沙漠化区内蒙古奈曼旗尧勒甸子村沙区土壤图为例,对沙漠化的现状及发展趋势进行了分数维分析,得到了较好的效果,认为该理论在沙漠化定量研究中具有很大的应用潜力。  相似文献   

The problem of the Quaternary, geological environment and desertification   总被引：2，自引：0，他引：2  

L. Nianfeng  T. Jie  Z. Dianfa 《Environmental Geology》1999,38(1):7-12

 The Quaternary geological environment supplied mankind with a habitat and rich natural resources such as forest, meadow, water, etc. Mankind has developed to modern civilization through a very long history. During the last 100 years the area of desertification has been expanding, natural resources have been consumed, and eco-environments plundered. Mankind felled forests, cultivated grassland, and increased farmland because of unceasing increasing population and the need for materials. In a period of 50–100 years, mankind's destruction could change good meadow into desert. The following examples are evidence: Shangdu grassland in Inner Mongolia and the west grassland of Jilin Province have been changing into desert rapidly. Two concepts of destructive power (D) and bearing capacity (B) can be used to describe this process. When D<B, the ecosystem keeps good circulation, D=B, eco-balance reaches critical state, and D>B, ecosystem loses balance, the environment is destroyed and developed toward desert. The law of destructive power increasing with time accords with logistic curves and can be expressed by a logistic model. Destructive power (D) increases with decrease of bearing capacity (B);D and B represent a reciprocal relation. With a logistic model the developing process of desertification can be studied and the developing rate and strength of change can be forecasted. Received: 20 July 1998 · Accepted: 1 December 1998  相似文献   

Effects of biological soil crusts on water infiltration and evaporation Yanchi Ningxia,Maowusu Desert,China   总被引：4，自引：0，他引：4  

《国际泥沙研究》2016,(4):311-323

Biological soil crusts serve as a vanguard for improving the ecological environment in arid, semi-arid desertification areas. It is a good indicator of the level of improvement which the local ecological environment is undertaking. In desert areas, water condition is a key factor of improving the ecological environment. As a first layer protection, biological crusts play an important role in local vegetation succession due to their abilities to conserve and maintain moisture. Using Maowusu desert in Yanchi of Ningxia province as an example, after three years of research, this paper chooses three kinds of biological crusts including lichen, moss and cyanobacterial which are under the cover of Artemisia ordosica as research objects. The results of this study indicate that, the closer biological crusts are to Artemisia ordosica vegetation, the thicker they become. In the same position of Artemisia ordosica vegetation, the thickness of moss crusts is the highest, followed by lichen crusts, and the thickness of cyanobacterial crusts is the lowest. Biological soil crusts coverage protects the natural water content of soil layers from 0 to 5 cm. Also, it effects falling water to infiltrate deeper, and cannot prevent the surface water content from evaporating effectively. The effect of biological crusts blocking water infiltration decreases with the increase of rainfall. At the same rainfall level, moss crusts provide the strongest water infiltration blockage, followed by lichen crusts and cyanobacterial crusts. With the increase of rainfall, the depth of water infiltration increases. At the same rainfall level, the relationship of water infiltration depth is as follows: cyanobacterial crusts 4 lichen crusts 4 moss crusts. With the increase of biological crusts thickness, they blocking water infiltration capacity is stronger, and the depth of water infiltration is smaller. Analysis on the characteristic of simulated rainfall process on biological crusts shows that sandy land can be fixed by applying appropriate artificial biological crusts to build a sustainable forest pro-tection system and to create a stable ecosystem in desertification area.  相似文献   

Plant Area Index and microclimate underneath shrub species from a Chilean semiarid community     

Y. Tracol  J.R. Gutiérrez  F.A. Squeo 《Journal of Arid Environments》2011,75(1):1-6

In drylands, environmental conditions under shrub canopy differ from those found in open sites. We should expect that microclimate conditions under shrubs with distinct canopy architecture should also be different. Plant Area Index (PAI) of the three most abundant shrubs species (Porlieria chilensis, Adesmia bedwellii and Proustia cuneifolia) in Bosque Fray Jorge National Park, north-central Chile was measured using a Plant Canopy Analyzer. During two years (2004-2005), we recorded the Relative Humidity and Air Temperature underneath and away from the canopy of the shrubs.The three shrub species showed significant differences in PAI. Microclimate at 30 cm and 2 m above the soil in the open conditions were drier and warmer than underneath shrub canopies. Vegetation patches generate moderate microclimate conditions.Canopy structure can buffer climatic variability, contributing to high herbaceous productivity as well as shrub recruitment. Reflecting shrub architecture and observed PAI values, the lowest microclimate variations were observed under the canopies of P. chilensis, followed by P. cuneifolia and finally A. bedwellii. We bring a novel approach quantifying the Plant Area Index instead of the Plant cover and using a low cost method that integrates the distribution of leaves and may be derived from remote sensing products.  相似文献   

Soil erosion rates in rangelands of northeastern Patagonia: A dendrogeomorphological analysis using exposed shrub roots     

Marcelo Pablo Chartier  Csar Mario Rostagno  Fidel Alejandro Roig 《Geomorphology》2009,106(3-4):344-351

Soil erosion is an important process of land degradation in many rangelands and a significant driver of desertification in the world's drylands. Dendrogeomorphology is an alternative to traditional methods for determining soil erosion rate. Specifically, the vertical distance between the upper portion of exposed roots and the actual soil surface can be used as a bioindicator of erosion since plant establishment. In this study, we determined (i) the soil erosion rate from exposed roots of the dwarf shrub Margyricarpus pinnatus [Lam.] Kuntze in two ecological sites in the northeastern rangelands of Patagonia and (ii) the relationship between shrub age and upper root diameter. We selected two ecological sites, a pediment-like plateau and a flank pediment, where the dominant soils were Xeric Haplocalcids and Xeric Calciargids, respectively. The soil erosion rates in the pediment-like plateau and in the flank pediment were 2.4 and 3.1 mm yr^− 1, respectively. Data clearly indicate a high rate of soil erosion during the mean 8-year life span of the dwarf shrubs in degraded patches, which represent ~ 10% of surface cover in the study area. Simple linear regression analysis yielded a highly significant predictive model for age estimation of M. pinnatus plants using the upper root diameter as a predictor variable. The measurement of ground lowering against datable exposed roots represents a simple method for the determination of soil erosion rates. In combination with other soil surface features, it was used to infer the episodic nature of soil erosion. This approach could be particularly useful for monitoring the effects of land management practices on recent soil erosion and for the establishment of records in regions where historical data regarding this process are scarce or absent.  相似文献   

喀斯特石漠化概念演绎及其科学内涵的探讨   总被引：252，自引：26，他引：226  

王世杰 《中国岩溶》2002,21(2):101-105

通过喀斯特石漠化概念、演绎过程的介绍,深入探讨了喀斯特石漠化的科学内涵。喀斯特石漠化是指在亚热带脆弱的喀斯特环境背景下,受人类不合理的社会经济活动的干扰破坏,造成土壤严重侵蚀,基岩大面积出露,土地生产力严重下降,地表出现类似荒漠景观的土地退化过程。喀斯特石漠化是土地荒漠化的主要类型之一,它以脆弱的生态地质环境为基础,以强烈的人类活动为驱动力,以土地生产力退化为本质,以出现类似荒漠景观为标志。   相似文献   

甘肃民勤绿洲沙漠化防治新对策   总被引：3，自引：0，他引：3  

李相博  孟易辰 《甘肃地质》2000,9(2):83-85

利用卫星遥感图像分析了民勤绿洲环境恶化的主要原因 ,提出目前除了要实行以往科学家所倡导的种种治理方案外 ,还应在民勤西北部雅布赖山的两个缺口处一带集中种植防护林并修建人工防护墙的新见解  相似文献   

陕北榆神府矿区煤炭资源开发主要水工环问题及防治对策   总被引：19，自引：0，他引：19  

叶贵钧  张莱等 《工程地质学报》2000,8(4):446-455

分析了榆神府矿区煤炭资源开发所面临的主要水文、工程、环境地质问题。以水文工程地质条件研究为基础 ,给出了榆神府矿区土地沙漠化、水土流失和水环境受开采影响的预期结果。并提出了实现保水采煤的水工环技术方案和工程措施建议。  相似文献   

不同排放情景下鄂尔多斯沙漠化风险预估     

耿怡颖  丁文广  刘兴德  徐浩  赵晨 《沙漠与绿洲气象(新疆气象)》2017,11(4):70-77

气候变化可以对沙漠化的扩张和逆转产生影响,综合预估未来多气候情景下沙漠化风险是制定防沙治沙策略的基础依据。基于鄂尔多斯1981—2015年NDVI数据和气候数据,利用最小二乘法对各年NDVI值、年降水量和年积温构成的时间序列进行线性倾向估计,对每个像元的值进行线性回归模型拟合,获取了未来35 a不同气候情景下的NDVI预测值,并在IPCC提出的4种气候变化情景下预测沙漠化风险状况,结果表明:(1)鄂尔多斯未来35 a沙漠化风险呈西北高、东南低的特点;(2)从气候变化情景看,在RCP8.5情景下,鄂尔多斯未来35 a的沙漠化风险最大,RCP6.0情景下风险最小;(3)从未来不同时期看,除RCP4.5情景外,未来15 a鄂尔多斯沙漠化风险最大,未来25~35 a沙漠化风险相对较小。  相似文献