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1.
根据近１０年国际荒漠化概念的演化及我国官方和学术界对荒漠化的新认识，并在前人有关荒漠化土地分类研究的基础上，本文尝试对我国荒漠化土地的类型按主营力（表１）和地表组成物质（表２）两种系统进行分类。 首先我们力图准确体现荒漠化概念的以下内涵：１）以土地退化为本质、因为土地退化本身是一个包括了土壤退化、植被退化和地表状况恶化在内的综合概念，所以不宜再单独将“土壤的理化性退化”或“植被的长期退化”作为荒漠化土地类型；２）与人类活动相关联。荒漠化不包括纯粹由自然因素形成的原生荒漠或类荒漠景观，所以，在目前… 相似文献
2.
基于RS和GIS的南汀河流域石漠化评价 总被引：3，自引：2，他引：1
以南汀河流域ETM、DEM和地质岩性数据为基础数据,应用遥感和地理信息技术提取了石漠化评价因子,构建石漠化评价指标并对石漠化强度进行评价。运用空间叠加分析和统计分析方法对石漠化信息进行分析,得到流域岩溶区石漠化强度分级特征,利用土地利用数据及石漠化信息与土地利用/覆盖类型的相关关系以分析土地利用方式对石漠化的影响。结果表明（1）研究区石漠化强度为:中度石漠化>轻度石漠化>潜在石漠化>强度石漠化>无石漠化>极强度石漠化。（2）强度石漠化区和极强度石漠化区主要分布在以耕地和疏林地为主要覆盖类型的区域。说明了造成石漠化的因素除裸岩率、植被、坡度、岩性等主要影响因子外,人们利用土地的方式对石漠化也具有很大促进作用。 相似文献
3.
河西走廓地区土地荒漠化问题分析 总被引：9，自引：0，他引：9
本文介绍了土地荒漠化的概念和类型以及河西走廓地区土地荒漠化的分布特征和危害特征,着重分析了该地区土地荒漠化形成的人为因素;人口与畜牧的巨增,植被的惨遭破坏,水资源的不合理开发利用;（１）流域中上游用水过量导致下游缺水,荒漠化发展;（２）过度开采地下水资源造成天然植被退化甚至死亡;（３）灌溉方式的不合理引起土壤盐渍化的发生和发展;（４）农业过多地占用水资源而不考虑周济树林,草地,致使生态平衡失调等。 相似文献
4.
近年来,中国北方地区强沙尘暴日益加剧,对首都北京的生态环境构成了威胁.首都圈农牧区人口和畜牧业压力过高,造成对土地的过度开垦利用,从而导致严重的土地荒漠化.以恢复重建自然植物群落为主的生态系统恢复是首都圈防沙、治沙的根本措施.本文就植被的生态需水规律、环境异质性对植被格局的影响、生态系统恢复的参照植被的建立和草地的退化程度与植被恢复的关系等4个方面进行了探讨.提出可持续发展应该作为首都圈防沙、治沙的目标,并讨论了生态学研究在可持续发展中的重要性. 相似文献
5.
西南地区2001-2014年植被变化时空格局 总被引：2，自引：0，他引：2
时序植被动态变化研究一直是全球变化研究的热点之一,对地区生态治理有重要意义。基于西南地区2001至 2014年的MODIS植被指数数据集以及DEM数据和土地利用数据,进行季节合成植被指数（SINDVI）的趋势模拟、空间统计和相关分析,探讨西南地区植被变化趋势和空间分异特征,研究结果表明:（1）74.52%的区域SINDVI变化不显著,显著改善的区域占22.07%,而显著退化的区域占3.41%,改善面积远远大于退化面积。（2）从地形因子结果来看,中低海拔地区和缓坡地区植被变化趋势最明显,海拔3 500 m以下植被变化趋势比海拔3 500 m以上明显。随着坡度的增加,改善趋势和退化趋势都在变小。（3）从土地利用分析结果来看,SINDVI变化趋势在人工表面最明显,改善和退化趋势都相对较大。（4）受人类活动的影响,人工表面和裸地的增多、林地的减少是植被呈退化趋势的主要原因。 相似文献
6.
内蒙额济纳绿洲环境恶化的思考 总被引：10，自引：0，他引：10
张惠昌 《水文地质工程地质》1994,21(6):48-52
本文介绍了黑河下游额济纳绿洲的自然概况和４０年来由于人类活动（盲目性和无政府状态、兴修水利工程、植被退化、片面追求目前的经济效益、短地行为等）造出水资源减少，地下水位持续下降，居延海干涸，土地沙漠化和盐渍化，植被退化等．其中主要原因是黑河下游的地表水径流量减少，中、下游开发利用不合理所致．全流域的管理协调水资源是解决额济纳绿洲环境恶化的先决条件．进而才能落实生态平衡的技术措施． 相似文献
7.
锡林郭勒典型草原植被高度和盖度对风吹雪的影响 总被引：2，自引：1，他引：1
采用野外调查与风雪流实测的方法对内蒙古锡林郭勒大针茅典型草场风雪流与植被高度、盖度的关系进行了研究.结果表明:随着草场退化程度的减轻和草场植被高度、盖度的增大,下垫面粗糙度、积雪厚度和积雪量呈增大趋势,而近地表风速、移雪强度与上层含雪量则呈下降趋势.移雪强度与距地表高度,积雪深度与植被高度,积雪深度与盖度间均符合指数函数关系.中度、轻度退化草场和封育草场的积雪深度分别是重度退化草场的1.7、3.1和5.2倍.随着退化程度的增加,风吹雪灾害形成的可能性增大.加强草原保护与建设,对减轻风吹雪危害和积蓄积雪资源具有重要作用. 相似文献
8.
系统阐明岩溶石漠化的演变趋势,对正确认识岩溶石漠化发生发展过程及实施有效的石漠化综合防治措施具有重要意义。研究表明:（1）驱动石漠化发生与形成的因素有岩溶山地农户生计单一、土地压力大、土地承载力低和生态脆弱等4个主要因素;石漠化发生扩展其实质就是在低土地承载力背景下,过伐、过垦、过牧等土地利用方式触发了岩溶山地土地退化,即石漠化。（2）岩溶石漠化在发生发展到一定阶段后,随着社会经济背景的演变和石漠化驱动因素的变化、消失,石漠化面积扩张的趋势会发生根本性的转折,即石漠化转型。（3）中国西南岩溶山地土地利用方式改变引起生态系统机制改变,从而引起石漠化转型演变。石漠化转型是土地利用系统对经济社会发展与生态系统综合作用的响应,符合经济社会发展和生态系统演化的总体趋势。（4）中国西南岩溶山地石漠化演变对揭示该区域人地关系变化具有指导意义。 相似文献
9.
10.
藏北草地资源及其演化趋势——以申扎地区为例 总被引：2，自引：0，他引：2
申扎地区属青藏高原南羌塘高寒草原区，具有典型的高原植被。根据水体条件、植被组成和地貌特征等，划分了7种草地植被类型和2个木本植物分布区。藏北地区生态系统十分脆弱，高原植被面临严峻的破坏、退化和沙漠化环境，生物链严重失调，高原鼠兔由于几乎没有天敌而大量繁殖。对高原草地的破坏因素进行分析认为：高寒、冻融作用、地下水位下降、雪线上升和冰川萎缩、猖獗的鼠害、超载过牧是高原植被(草地)退化的主要因素，其中高寒、缺水、鼠害和超载过牧是最重要的原因。藏北申扎地区年降水量与年蒸发量比例为约1：9，湿地和植被供水系统受到严重损害，造成大面积草场萎缩，形成了环状草地退化带。藏北草地向恶化方向发展是不可逆的，根治鼠害，改良牲畜品种，提高经济效益，可以减缓草场退化速度。 相似文献
11.
Douglas L. Johnson 《GeoJournal》1993,31(1):51-66
Desertification in areas where traditional pastoral nomadism was common is a phenomenon of this century. Nomads possessed institutions and management practices that avoided excess concentrations of people and animals, rotated grazing pressure seasonally between major pasture zones, protected dry season resources that were critical to their survival, and limited access to pastoral resources. These systems of management and control have broken down and degradation of pastoral lands has been the result. The pressures promoting desertification include agricultural expansion into pastoral zones, the loss of critical dry season pasture, sedentarization of former nomads, the impacts of war and civil conflict, nationalization of pastoral resources, the collapse of traditional common property resource management systems, and social change and economic intensification. These processes have concentrated pastoral pressures into more limited spaces and increased the stress placed on natural resources to the point where land degradation takes place. These adverse changes can be avoided and desertification arrested if principles of proper management are applied. By planning holistically, using the ethnoscientific wisdom of nomadic pastoralists as a basis for development, protecting zones critical to the survival of pastoralists, retaining mobility and flexibility in contemporary pastoral systems, and strengthening common property systems developed by nomadic pastoralists, land degradation in dryland rangelands can be halted. 相似文献
12.
Arid karst landscapes that have been degraded by human activities provide a challenge for rehabilitation and an opportunity
to test ideas about the stability and resilience of limestone ecosystems. The Nullarbor Plain is the largest arid karst area
in Australia (220 000 km2) and is divided into extensive closed karstic depressions separated by low rocky ridges, while the dominant vegetation is
chenopod shrubland. Since European settlement there has been considerable change in the vegetation, with significant reduction
in shrub and grass cover over large areas of the plain. These changes are related to a state and transition model of vegetation
dynamics which incorporates climatic variability, fire history and grazing pressure from sheep, kangaroos and rabbits. A partial
sediment budget using 137Cs inventories reveals local and regional patterns of soil redistribution within this arid karst landscape. Rehabilitation
of eroded soil in pastoral lands has been accomplished at several sites but is labour intensive and vulnerable to climatic
fluctuations. Given the low stock numbers, limited number of people involved, and poor economic returns, it would be sensible
to make pastoral activities on the Nullarbor secondary to conservation priorities. This would necessitate a change in land
ethic to stewardship, with emphasis on rehabilitation and control of feral animals. Management of increased numbers of visitors
to the caves and karst also requires that resource inventories and management plans for each area be drawn up and used.
Received: 1 June 1995 · Accepted: 4 December 1995 相似文献
13.
Historical and exact information about the land use/land cover change is very important for regional sustainable development. The aim of this paper is to determine the rapid changes in land use/land cover (LULC) pattern due to agriculture expansion, environmental calamities such as flood and government policies over Upper Narmada basin, India. Multi-temporal Landsat satellite images for years 1990, 2000, 2010 and 2015 were used to analyze and monitor the changes in LULC with an overall accuracy of more than 85%. Results revealed a potential decrease in natural vegetation (? 9.52%) due to the expansion of settlement (+ 0.52%) and cropland (+ 9.43%) from 1990 to 2015. In the present study, Cellular Automata and Markov (CA–Markov), an integrated tool was used to project the short-term LULC map of year 2030. The projected LULC (2030) indicated the expansion of built-up area along with the cropland and degradation in the vegetation area. The outcomes from the study can help as a guiding tool for protection of natural vegetation and the management of the built-up area. Additionally, it will help in devising the strategies to utilize every bit of land in the study area for decision makers. 相似文献
14.
Hassan Yeganeh Seyed jamale Khajedein Fazel Amiri Abdul Rashid B. Mohamed Shariff 《Arabian Journal of Geosciences》2014,7(1):287-298
The aim of the present research is to monitor changes in herbage production during the grazing season in the Semirom and Brojen regions, Iran, using multitemporal Moderate Resolution Imaging Spectroradiometer (MODIS) data. At first, various preprocessing steps were applied to a topography map. The atmospheric and topographic corrections were applied using subtraction of the dark object method and the Lambert method. Image processing, including false-color composite, principal component analysis, and vegetation indices were employed to produce land use and pasture production maps. Vegetation sampling was carried out over a period of 4 months during June–September 2008, using a stratified random sampling method. Twenty random sampling points were selected, and herbage production was estimated and verified with the double-checking method. Four MODIS data sets were used in this study. The models for image processing and integrating ground data with satellite images were processed, and the resulting images were categorized into seven classes. Finally, the land covers were verified for accuracy. A postclassification analysis was carried out to verify the seven class change detections. The results confirmed that Normalized Difference Vegetation Index (NDVI) and Soil-Adjusted Vegetation Index (SAVI) maps had a close relationship with the field data. The indices produced with shortwave infrared bands had a close relationship with field data where the ground cover and yields were high. The R 2 value observed was 0.85. The changes in the pasture vegetation were high during the growing season in more than 90 % of the pastures. During the growing season, most changes in the pastures belonged to class 5 and 2 in the NDVI and SAVI index maps, respectively. 相似文献
15.
Trends and variation in vegetation greenness related to geographic controls in middle and eastern Inner Mongolia,China 总被引：1，自引：1，他引：0
Extensive studies have investigated the relationships between climate change and vegetation dynamics. However, the geographic
controls on vegetation dynamics are rarely studied. In this study, the geographic controls on the trends and variation of
vegetation greenness in middle and eastern Inner Mongolia, China (mid-eastern Inner Mongolia) were investigated. The SPOT
VEGETATION 10-day period synthesis archive of normalized difference vegetation index (NDVI) from 1999 to 2007 was used for
this study. First, the maximum value compositing (MVC) method was applied to derive monthly maximum NDVI (MNDVI), and then
yearly mean NDVI (YMNDVI) was calculated by averaging the MNDVIs. The greenness rate of change (GRC) and the coefficient of
variation (CV) were used to monitor the trends and variation in YMNDVI at each raster grid for different vegetation types,
which were determined from a land use dataset at a scale of 1:100,000, interpreted from Landsat TM images in 2000. The possible
effects of geographic factors including elevation, slope and aspect on GRC and CV for three main vegetation types (cropland,
forest and steppe) were analyzed. The results indicate that the average NDVI values during the 9-year study period for steppe,
forest and cropland were 0.26, 0.41 and 0.32, respectively; while the GRC was 0.008, 0.042 and 0.033 per decade, respectively;
and CVs were 10.2, 4.8 and 7.1%, respectively. Cropland and steppe shared a similar trend in NDVI variation, with both decreasing
initially and then increasing over the study period. The forest YMNDVI increased throughout the study period. The GRCs of
the forest also increased, although GRCs for cropland and steppe decreased with increasing elevation. The GRCs of cropland
and steppe increased with increasing slope, but the forest GRCs were not as closely related to slope. All three vegetation
types exhibited the same effects in that the GRC was larger on north-facing (shady) slopes than south-facing slopes due to
differences in water conditions. The CVs of the three vegetation types showed different features to the GRC. The CVs for all
three vegetation types were not affected by aspect. The CVs for forest and cropland showed minor effects with changes in elevation
and slope, but the CV for steppe decreased with increasing slope, and increased with increasing elevations to 1,200 m, before
decreasing at higher elevations. Our findings suggest that the role of geographic factors in controlling GRC should also be
considered alongside climate factors. 相似文献
16.
Identifying effective vegetation biophysical and spectral parameters for investigating light to moderate grazing effects on grasslands improves management practices on grasslands. Using mixed grasslands as a case study, this paper compares responses of vegetation biophysical properties and spectral parameters derived from satellite images to grazing intensity, and identifies the suitable biophysical and spectral parameters to detect grazing effects in these areas. Biophysical properties including cover, canopy height and Leaf area index (LAI) were measured in three sites with different grazing managements and one benchmark site in 2008 and 2009 in Grasslands PlaceTypeNational Park and surrounding provincial pastures, Canada. Thirteen vegetation spectral indices, calculated by statistically combining different spectral information, were evaluated. The results indicate that canopy height and the ratio of photosynthetically active vegetation cover to non-photosynthetically active vegetation cover (PV/NPV) showed significant differences between ungrazed and grazed sites. All spectral vegetation indices except the canopy index (CI) show significant differences between grazing treatments. Red-Near infrared (Red-NIR) based vegetation indices, such as Modified Triangular Vegetation Index 1 (MTVI1), Soil-adjusted Vegetation Index (SAVI), are significantly correlated to the PV/NPV. Green/Mid-infrared (Green/MIR) related vegetation indices, i.e. Plant Senescence Reflectance Index (PRSI) and Normalized Canopy Index (NCI), show significant correlation with canopy height. Models based on a linear combination of MTVI1 and SAVI were developed for PV/NPV and PRSI and NCI for canopy height. Models that simulated PV/NPV and canopy height show significant correlations with grazing intensity, suggesting the feasibility of remote sensing to quantify light to moderate grazing effects in mixed grasslands. 相似文献
17.
内蒙古半干旱草原气候生态相互作用问题——IMGRASS计划初步结果 总被引：23，自引：1，他引：22
IMGRASS计划 (内蒙古半干旱草原土壤植被大气相互作用 )旨在通过野外实验、过程分析和数值模式研究理解中纬度半干旱草原气候生态相互作用中的多种时空尺度和多种物理化学生物学过程的作用 ,以及人类活动的影响。文中介绍部分与全球变化和人类活动相关的初步研究结果 ,主要是 :(1)冬季风、大区域地表环境和本区地形的结合对浑善达克沙地在长时间过程形成的作用 ;(2 )夏季风、本区地形和植被对本区夏季降水的水汽通道和降水分布有重要作用 ;(3)实验区内不同类型地表与土壤表现出明显不同的地气交换通量特征与不同的边界层结构 ;(4 )草原温室气体 (N2 O ,CH4 ,CO2 )收支的定量测量与过程研究表明 ,温带草原N2 O源强较IPCC 2 0 0 1报告估计值偏低 ,而草原CO2 收支表现出很强的变动性 ;(5 )人类活动干预下的草原退化与恢复演替表现出该区域普遍的规律与对气候的依赖 ,提供可持续发展的人类对自然草原放牧强度的阈值。 相似文献
18.
Land cover change over the last three centuries due to human activities: The availability of new global data sets 总被引：15，自引：0，他引：15
Land use and land cover change is an important driver of global change (Turner et al., 1993). It is recognized that land use change has important consequences for global and regional climates, the global biogeochemical cycles such as carbon, nitrogen, and water, biodiversity, etc. Nevertheless, there have been relatively few comprehensive studies of global, long-term historical changes in land cover due to land use. In this paper, we review the development of global scale data sets of land use and land cover change. Furthermore, we assess the differences between two recently developed global data sets of historical land cover change due to land use. Based on historical statistical inventories (e.g. census data, tax records, land surveys, historical geography estimates, etc) and applying different spatial analysis techniques, changes in agricultural land cover (croplands, pastures) were reconstructed for the last 300 years. The two data sets indicate that cropland areas expanded from 3–4 million km2 in 1700 to 15–18 million km2 in 1990 (mostly at the expense of forests), while grazing land area expanded from 5 million km2 in 1700 to 31 million km2 in 1990 (mostly at the expense of natural grasslands). The data sets disagree most over Latin America and Oceania, and agree best over North America. Major differences in the two data sets can be explained by the use of a fractional versus Boolean approach, different modelling assumptions, and inventory data sets. 相似文献
19.
Fazel Amiri Abdul Rashid bin Mohamed Shariff Taybeh Tabatabaie Biswajeet Pradhan 《Arabian Journal of Geosciences》2014,7(3):1101-1114
Extensive livestock grazing even in unsuitable land has increasingly grown in most parts of semi-arid rangeland. Therefore, it is of paramount importance to identify suitable land for livestock grazing for optimum utilization while causing minimum impact to the environment. This paper adapted the schematic model based on the concepts presented by the Food and Agriculture Organization of suitability analysis for optimal grazing management in semi-arid rangeland in Iran. Factors affecting extensive grazing were determined and incorporated into the model. Semi-arid rangeland with variable such as climate and other agents were examined for common types of animal grazing and the advantages and limitations were elicited. Many ecosystem components affect land suitability for livestock grazing but due to time and funding restrictions, the most important and feasible elements were investigated. Within the model parameters, three submodels including water accessibility source, forage production, and erosion sensitivity were considered. Suitable areas at four levels of suitability were determined using geographic information systems. This suitability modeling approach was adopted due to its simplicity and the minimal time required for transforming and analyzing datasets. The most important reducing factors in model suitability were found to be: (a) land use and vegetation cover (in relation to soil erosion sensitivity), (b) the amount of the available forage in comparison with the total production, and (c) the existence of less palatability plants among the pasture plant species (forage production suitability). The results of the study would be beneficial to rangeland managers in devising measures more wisely to cope with the limitations and enhance the health and productivity of the rangelands. 相似文献
20.
Geospatial tools for assessing land degradation in Budgam district,Kashmir Himalaya,India 总被引：1，自引：0，他引：1
MEHNAZ RASHID MAHJOOR AHMAD LONE SHAKIL AHMAD ROMSHOO 《Journal of Earth System Science》2011,120(3):423-433
Land degradation reduces the ability of the land to perform many biophysical and chemical functions. The main aim of this
study was to determine the status of land degradation in the Budgam area of Kashmir Himalaya using remote sensing and geographic
information system. The satellite data together with other geospatial datasets were used to quantify different categories
of land degradation. The results were validated in the field and an accuracy of 85% was observed. Land use/land cover of the
study area was determined in order to know the effect of land use on the rate of land degradation. Normalized differential
vegetation index (NDVI) and slope of the area were determined using LANDSAT-enhanced thematic mapper plus (ETM+) data, advanced
space borne thermal emission and reflection radiometer, and digital elevation model along with other secondary data were analysed
to create various thematic maps, viz., land use/land cover, geology, NDVI and slopes used in modelling land degradation in
the Kashmir Himalayan region. The vegetation condition, elevation and land use/land cover information of the area were integrated
to assess the land degradation scenario in the area using the ArcGIS ‘Spatial Analyst Module’. The results reveal that about
13.19% of the study area has undergone moderate to high degradation, whereas about 44.12% of the area has undergone slight
degradation. 相似文献