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1.
THE EFFECT OF LAND USE CHANGES ON SOIL CONDITIONS IN ARID REGION   总被引：1，自引：1，他引：0  
Biography:CHEN Fu(1974－ ), male,a native of Sheyang County, Jiangsu Province, doctoral candidate.His research interests include land use management.1 INTRODUCTION Land use change may influence a variety of natural and ecological processes, including soil nutrient, soil moisture, soil erosion, land productivity (FU et al.， 1999), biodiversity, cycle of biographical geochemistry, and so on (VITOUSEK, 1994). So, it is very important that the studies of land use changes understand re…  相似文献   

2.
This paper synthesized the principal land denudation processes and their role in determining riverine suspended sediment yields(SSY) in two typical geographical environments of the Upper Yangtze River Basin in China and the Volga River Basin in Eastern Europe. In the Upper Yangtze River Basin, natural factors including topography, climate,lithology and tectonic activity are responsible for the spatial variation in the magnitude of denudation rates.Human disturbances have contributed to the temporal changes of soil erosion and fluvial SSY during the past decades. On one hand, land use change caused by deforestation and land reclamation has played an important role in the acceleration of sediment production from the central hilly area and lower Jinsha catchment; On the other hand, diverse soil conservation practices(e.g., reforestation,terracing) have contributed to a reduction of soil erosion and sediment production since the late 1980 s.It was difficult to explicitly decouple the effect of mitigation measures in the Lower Jinsha River Basindue to the complexity associated with sediment redistribution within river channels(active channel migration and significant sedimentation). The whole basin can be subdivided into seven sub-regions according to the different proportional inputs of principal denudation processes to riverine SSY. In the Volga River Basin, anthropogenic sheet, rill and gully erosion are the predominant denudation processes in the southern region, while channel bank and bed erosion constitutes the main source of riverine suspended sediment flux in the northern part of the basin. Distribution of cultivated lands significantly determined the intensity of denudation processes.Local relief characteristics also considerably influence soil erosion rates and SSY in the southern Volga River Basin. Lithology, soil cover and climate conditions determined the spatial distribution of sheet, rill and gully erosion intensity, but they play a secondary role in SSY spatial variation.  相似文献   

3.
中国北方典型农牧交错区的土壤风蚀危险度研究   总被引：1，自引：0，他引：1  
土壤风蚀及其引发的土地退化、沙化和沙尘暴是中国北方严重的环境问题之一。通过定量评估中国北方典型农牧交错地区土壤风蚀危险程度,可以为区域生态环境的保护和生态修复提供科学支撑。本文基于文献调研、兼顾数据的可获得性,建立了包括风场强度、植被覆盖率、地形起伏度、土壤干燥度等因子在内的风蚀危险程度评价指标体系。同时,依据遥感参数反演和地面气象观测数据,在地理信息系统技术支持下,形成了上述因子的空间分布数据。另外,利用层次分析方法,构建土壤风蚀危险度评价模型,得到研究区土壤风蚀危险度的空间分布。最后,结合研究区土地利用数据,探讨了风蚀危险度空间分布格局的自然环境和土地利用背景。研究表明:研究区土壤风蚀极险型区域面积为1.47×104km2,强险型区域面积为6.09×104km2,危险型区域面积为3.47×104km2,轻险型区域面积为3.45×104km2,无险型区域面积为2.19×104km2。本区土壤风蚀危险度呈现出从东南到西北逐渐增强的趋势,这与区域的植被、气候,以及土地利用的空间格局具有内在的有机联系。  相似文献   

4.
Shifting cultivation is a traditional farming system practiced in the tropical mountainous areas. Although it has been widely perceived as an economically inefficient and environmentally harmful agricultural production system, recent science reviews, however, indicate that the deleterious impacts of shifting cultivation on environment may have been overestimated. Despite the pressures of agricultural intensification in areas where shifting cultivation occurs, farmers across the tropics still maintain this traditional farming system. The objective of this study was to explore existing traditional shifting cultivation practices and their various modifications including the innovative farming techniques developed by farmers in the Chittagong Hill Tracts (CHTs), the mountainous region of Bangladesh, and examine their importance with respect to recent socio-economic and environmental changes. The study revealed that shifting cultivation still exists as the most dominant farming method which supports livelihoods and culture of the hill ethnic people. However, demand for more food and household income to meet livelihood needs of an increasing population combined with a rapid deterioration of soil and water quality over decades contributed to development of innovative farming practices through fallow land farming, crop substitution, agroforestry and homestead gardening in the CHTs. Through these farming techniques farmers maintain a strong relationship with traditional knowledge system embedded in the age-old shifting cultivation practices. Today state policies and market forces act in favor of replacement of traditional farming with intensive cash crop agriculture. It seems that disappearance of traditional farming practices from the hills may threaten local biodiversity and food security. It may be recommended that shifting cultivation should be encouraged in areas where they have potential for contributing to preservation of native biodiversity and ecosystem services, and protection of local peoples’ food security and cultural identity.  相似文献   

5.
Under global warming, storm events tend to intensify, particularly in monsoon-affected regions.As an important agricultural area in China, the purple soil region in the Sichuan Basin, where it has a prevailing monsoon climate, is threatened by serious soil erosion. Tillage operations alter runoff and soil erosion processes on croplands by changing the physical properties of the soil surface. To clarify the relationship between tillage and soil erosion in the purple soil region, three different tillage practices in this region were investigated at the plot scale over 4 years: bare land with minimum tillage(BL),conventional tillage(CT) and seasonal no-tillage ridges(SNTR) which was initially designed to prevent soil erosion by contoured ridges and no-tillage techniques. The results showed that although there were no significant differences in the surface runoff and soil erosion among the three practices, BL causedrelatively high surface runoff and soil erosion,followed by CT and SNTR. Classification and comparison of the rainfall events based on cluster analysis(CA) verified that the surface runoff was not significantly different between most intensive event and long intensive events but was significantly different between most intensive and short and medium-duration events. Only the rainfall events with the highest rainfall intensity could trigger serious soil erosion, up to 1000 kg ha-1 in the region. Further detailed investigations on the effects of tillage operations on the soil erosion in a subtropical region with a monsoon climate are needed to provide a basis for modeling catchments and designing better management practices.  相似文献   

6.
In order to study land use and cover changes (LUCC), especially urbanization accompanied soil degradation, authors used Asia DMSP/OLS data in 1992, Land Cover Data of Asia in 1992 and Global Assessment of Human Induced Soil Degradation (GLASOD, by ISRIC) in 1992, etc. In China the major type of soil degradation is water erosion, which is widely distributed especially in Loess Plateau and in Southeast and Southwest China and happened in forestland, grassland and arable land and mainly resulted from deforestation. The secondary type is wind erosion, which is mainly distributed in Northwest China and happened in arable land and grassland and was mainly caused by overgrazing. Chemical deterioration is mainly distributed in North and Northwest China and happened in paddy, arable land and grassland. Physical deterioration only concentrated in local area in North China and happened in arable land and paddy. Chemical and physical deterioration were resulted from unreasonable agricultural activity. From city to city + 200km with different distance away from city, different types and strength of human activities resulted in different types and distributions of soil degradation. In China human activity mainly concentrated within city+ 50km, therefore, accompanied soil degradation, such as chemical and physical deterioration, mainly happened near and around city.  相似文献   

7.
我国东北地区的自然环境状况一直备受关注,其土地沙化、荒漠化、林地草地退化、森林退化、土地盐碱化等土地环境变化的原因及监测一直是科研的焦点。随着“美丽中国中脊带”的提出,位于该线东北段附近的土地环境相关的研究也不断开展。在涉及该区域土地状况的研究中,常用研究方法有实地考察以及基于遥感卫星影像来进行分析,而本文利用知识图谱技术来构建相关文献研究的知识谱系,从另一个角度探究东北土地的环境状况变化因素。首先,由于知识图谱可以广泛探究文本数据之间的关联,且便捷高效,因此本文用科学知识图谱的有关方法对目前探究东北地区土地环境变化影响因素的4318篇CNKI文献进行挖掘,再用关键词共现的方法提取大量文献中已探明的目标因素,从而构建比较全面的基于东北地区环境研究的知识谱系,这一方法不仅省时省力,而且可以归纳出比较全面的影响因素;其次,结合聚类分析归纳出影响东北地区土地变化的主要因素,并进行分析。最后,选取词频前十的因素进行汇总,统计得出东北地区土地环境变化的影响因素,如影响土地沙化的因素中,频数最高的关键词有生态环境破坏、水土流失、沙尘暴等,影响土地沙化的因素中,水土流失、土壤沙化、水资源不足等频数最高,这些因素分别代表了我国东北地区土地沙化、荒漠化、盐碱化、草地草场退化、林地退化、森林退化以及黑土地退化等土地环境变化的最主要因素。这一方法将为今后从知识图谱文本挖掘的方面深入探究地理、气候等自然现象的影响因素提供新的思路。  相似文献   

8.
1INTRODUCTIONSerioussoilerosionhasmadetheeco-environmentfragileintheLoessPlateau.InthemodernsoilerosionoftheLoessPlateau,theman-madeerosionwasthedominanterosionpattern (TANGetal.,1993a,1993b).Manyhumanactivitiesacceleratesoilerosion,butthemostinfluentialactivitiesaretodestroyforestandgrass,eventodestroyallvegetation.Reclamationbydestroyingforestlandandgrasslandartificiallycouldrapidlyincreasesoilerosionintensityinshorttimeandenlargeerosionspacegradually,evenchangeerosiondirectionandwor…  相似文献   

9.
The northeastern China, the United States, and the western Europe are important agricultural regions both on the global and regional scales. The western Europe has a longer history of agricultural land development than the eastern United States. These two regions have changed from the deforestation and reclamation phase in the past to the current land abandonment and reforestation phase. Compared with the two regions, large-scale land exploitation has only been practiced in the northeastern China during the last century. After a short high-intensity deforestation and reclamation period, agricultural and forest lands are basically in a dynamic steady state. By comparing domestic and international agro-forestry development and considering the ecological environment and socio-economic benefits that can be derived from agro-forestry, this paper suggests that large area of reforestation would be inevitable in future though persistent and large agricultural demand in coming decades even more. And local reforestation at slope farmland with ecological vulnerability should be imperative at present to avoid severer damage. At the same time, from the perspective of Land Change Science, the results demonstrate that the research on land use change in the agro-forestry ecotone is typical and critical, particularly those dealing with the analysis of spatial and temporal characteristics and the simulation of climate, hydrology, and other environmental effects.  相似文献   

10.
LAND RECLAMATION PROCESS IN NORTHEAST CHINA SINCE 1900   总被引：2，自引：1，他引：1  
Landuse/coverchange(LUCC)isafocalthemeandemergingissueinthestudyofglobalenvironmentalchange.Humanmodificationsandalterationstotheenvironmentcauseimpactsonthesurfaceoftheearth,threatenglobalsustainabilityandlivelihoodsystems,andcontributetochangeinthebiogeochemicalcyclesoftheearth,whichinturnaffectatmosphericlevelsofgreenhouseandothertracegases.ConsequentlytheInternationalGeosphere-BiosphereProgram(IGBP)andtheInternationalHumanDimensionsProgram(IHDP)initiatedLUCCProgramtodevelopabette…  相似文献   

11.
Land-use change is an important aspect of global environment change. It is, in a sense, the direct result of human activities influencing our physical environment. Supported by the dynamic serving system of national resources, including both the environment database and GIS technology, this paper analyzed the land-use change in northeastern China in the past ten years (1990–2000). It divides northeastern China into five land-use zones based on the dynamic degree (DD) of land-use: woodland/grassland — arable land conversion zone, dry land — paddy field conversion zone, urban expansion zone, interlocked zone of farming and pasturing, and reclamation and abandoned zone. In the past ten years, land-use change of northeastern China can be generalized as follows: increase of cropland area was obvious, paddy field and dry land increased by 74.9 and 276.0 thousand ha respectively; urban area expanded rapidly, area of town and rural residence increased by 76.8 thousand ha; area of forest and grassland decreased sharply with the amount of 1399.0 and 1521.3 thousand ha respectively; area of water body and unused land increased by 148.4 and 513.9 thousand ha respectively. Besides a comprehensive analysis of the spatial patterns of land use, this paper also discusses the driving forces in each land-use dynamic zones. The study shows that some key biophysical factors affect conspicuously the conversion of different land-use types. In this paper, the relationships between land-use conversion and DEM, accumulated temperature (⩾10°C) and precipitation were analysed and represented. We conclude that the land-use changes in northeast China resulted from the change of macro social and economic factors and local physical elements. Rapid population growth and management changes, in some sense, can explain the shaping of woodland/grassland — cropland conversion zone. The conversion from dry land to paddy field in the dry land — paddy field conversion zone, apart from the physical elements change promoting the expansion of paddy field, results from two reasons: one is that the implementation of market-economy in China has given farmers the right to decide what they plant and how they plant their crops, the other factor is originated partially from the change of dietary habit with the social and economic development. The conversion from paddy field to dry land is caused prmarily by the shortfall of irrigation water, which in turn is caused by poor water allocation management by local governments. The shaping of the reclamation and abandoned zone is partially due to the lack of environment protection consciousness among pioneer settlers. The reason for the conversion from grassland to cropland is the relatively higher profits of farming than that of pasturing in the interlocked zone of farming and pasturing. In northeastern China, the rapid expansion of built-up areas results from two factors: the first is its small number of towns; the second comes from the huge potential for expansion of existing towns and cities. It is noticeable that urban expansion in the northeastern China is characterized by gentle topographic relief and low population density. Physiognomy, transportation and economy exert great influences on the urban expansion. Foundation item: Under the auspices of Knowledge Innovation program Key Project of the Chinese Academy of Sciences (KZCX-2-308). Biography: LIU Ji-yuan (1947 - ), male, a native of Shanghai Municipality, professor, Director General of Institute of Geographical Sciences and Natural Resources Research, the Chinese Academy of Sciences. His research interests include environment and resources, remote sensing and geography.  相似文献   

12.
China is one of the ancient civilization countries. Owing to the blind reclamation, the vegetation had been destroyed, causing soil erosion and desertification, and making the civilization center move to the Changjiang (Yangtze) River valley from the Huanghe (Yellow) River. This movement began in the Qin and Han dynasties (221 B.C-220 A.D.) because at that time the large-scale reclamation was felled, the grassland was reclaimed into farmland, the vegetation was seriously destroyed in the loess and north of the Huanghe River, and the climate was getting colder; and the turn from north to south occurred in the Sui and Tang dynasties (581-907 A.D.) and completed in the Song Dynasty (960-1279 A.D.). However, at present the vegetation damage of the Changjiang River valley is very serious too and the silt carrying capacity of the Changjiang River is increasing sharply; thus the Changjiang River is in danger of becoming a second Huanghe River, so we must pay attention to the protection of ecological environmen  相似文献   

13.
Gully erosion regionalization of black soil area in northeastern China   总被引：7，自引：0，他引：7  
Gully erosion is the frequent and main form of soil erosion in the black soil area of the northeastern China, which is one of the most important commodity grain production bases in China. It is encroaching upon the fertile farmland there. Regionalization of gully erosion can reveal the spatial distribution and regularity of the development of gully erosion. Based on the eco-geographical regional background features of the black soil area, this study combined the regionalization with influencing factors of the development of gully erosion. GIS spatial analysis, geostatistical analysis, spatial statistics, reclassification, debris polygon processing and map algebra methods were employed. As a result, the black soil area was divided into 12 subregions. The field survey data on type, length, volume and other characteristics indicators of gully erosion were used to calibrate the results. Then the features of every subregion, such as where the gully erosion is, how serious it is, and why it happens and develops, were expounded. The result is not only an essential prerequisite for gully erosion surveys and monitoring, but also an important basis for gully erosion prevention.  相似文献   

14.
Severe soil erosion in the middle and upper reaches of Yangtze River has been regarded as a major environmental problem. The on-site impact of soil erosion on agricultural production and the off-site impact on floods and sedimentation in Yangtze Rive are well known. A quantitative assessment of soil erosion intensity is still scanty for developing appropriate soil erosion control measures for different land use types and zohes in this region. This article constructs a localized USLE and estimates the average soil loss in the Jinsha River Region in Yunnan Province, one of the priority areas for soil erosion control in the middle and upper reaches of Yangtze River. The estimation is done under different land uses and zones in this basin. The estimation shows that while soil erosion in the cultivated land is the most severe, 36～40% of the garden and forest land suffers from soil erosion of various degrees due to lack of ground cover and other factors. Soil erosion in the pasture is modest when the ground cover is well maintained. It also confirmed that terracing can reduce soil erosion intensity significantly on the cultivated land. Research findings suggest that sufficient attention must be paid to regeneration of the ground cover in reforestation programs. In addition to mass reforestation efforts, restoration of grassland and terracing of the cultivated land should also play an important role in erosion control.  相似文献   

15.
Various kinds of human disturbances on cropland are the main reasons for soil erosion and land degradation. Farming practices in mountainous areas vary greatly among cropland plots because of the heterogeneity of biophysical conditions and differences in farmers’ management behavior. The main purpose of this paper is to develop a composite index of cropland physical disturbance intensity (CLDI) to reflect the plot-scale discrepancy of potential soil erosion in mountainous areas. The study was based on both plot survey and household interview data, collected from six typical catchments in mountainous areas of southwestern China. Four kinds of physical disturbance practices and two kinds of conservation practices during one crop rotation period were synthesized to develop the CLDI index. The rough set theory was referenced to avoid subjectivity during weight allocation. The results show that conventional tillage, deep fertilization, and manual weeding are the main causes of cropland soil erosion, whereas manure application in combination with seasonal fallow reduces soil erosion. Different crop types as well as cropland location factors determine the spatial pattern of CLDI. Crop rotation modes with major crops of tobacco and maize resulted in a maximal CLDI, and cropland plots with a distance radius of 150 meters away from households received the most intensive physical disturbance. These results are critical to help better protect rural environments in mountainous areas. Based on the results, methods to reduce cropland soil erosion are suggested.  相似文献   

16.
This paper tries to qualitatively analyze land use and cover changes (LUCC) and accompanied soil degradation in China, the data of World Atlas of Agriculture in 1969, Land Cover Data of Asia in 1992 and Global Assessment of Human Induced Soil Degradation in 1992, etc. have been used. From 1960' s to 1990's, the area of forestland had increased, arable land and paddy as well as grassland had significantly decreased in China. The major type of soil degradation is due to water erosion, which is widely distributed especially in Loess Plateau and in Southeast and Southwest China, this happened in forestland, grassland and arable land and mainly resulted from deforestation. The secondary type is wind erosion, which is mainly distributed in Northwest China, it happened in arable land and grassland and was caused by overgrazing. Chemical deterioration is distributed in North and Northwest China, which happened in paddy, arable land and grassland. Physical deterioration only concentrated in local area in North China, it happened in arable and paddy. Chemical and physical deteriora-tion mainly resulted from unreasonable activity. Because of different human activities, different LUCC and different natural conditions, the types and strength of soil degradation can be different.  相似文献   

17.
LUCC and Accompanied Soil Degradation in China from 1960''''s to 1990''''s   总被引：1，自引：0，他引：1  
This paper tries to qualitatively analyze land use and cover changes (LUCC) and accompanied soil degradation in China, the data of World Atlas of Agriculture in 1969, Land Cover Data of Asia in 1992 and Global Assessment of Human Induced Soil Degradation in 1992, etc. have been used. From 1960' s to 1990's, the area of forestland had increased, ara-ble land and paddy as well as grassland had significantly decreased in China. The major type of soil degradation is due to wa-ter erosion, which is widely distributed especially in Loess Plateau and in Southeast and Southwest China, this happened in forestland, grassland and arable land and mainly resulted from deforestation. The secondary type is wind erosion, which is mainly distributed in Northwest China, it happened in arable land and grassland and was caused by overgrazing. Chemical deterioration is distributed in North and Northwest China, which happened in paddy, arable land and grassland. Physical de-terioration only concentrated in local area in North  相似文献   

18.
China is experiencing conflicts between its large population and scarce arable land, and between a demand for high productivity and the severe soil erosion of arable land. Since 1949, China has committed to soil and water conservation(SWC), for which eight regions and 41 subregions have been developed to improve the environment and increase land productivity. To obtain information from the regional planning and strategies for SWC and to explore whether SWC practices simultaneously contribute to soil conservation, ecosystem functioning, and the livelihoods of local farmers, and to summarize the successful experiences of various SWC paradigms with distinct characteristics and mechanisms of soil erosion, this paper systematically presents seven SWC regions(excluding the Tibetan Plateau region) and 14 typical SWC paradigms, focusing on erosion mechanisms and the key challenges or issues in the seven regions as well as on the core problems, main objectives, key technologies, and the performance of the 14 typical paradigms. In summary, the 14 typical SWC paradigms successfully prevent and control local soil erosion, and have largely enhanced, or at least do not harm, the livelihoods of local farmers. However, there remain many challenges and issues on SWC and socioeconomic development that need to be addressed in the seven SWC regions. China, thus, still has a long way to go in successfully gaining the win-win objective of SWC and human aspects of development.  相似文献   

19.
研究历史时期的土地利用与土地覆被变化,对于人类的生产活动有着重要的借鉴意义。本文以吉林省镇赉县为例,探讨了地名志等历史资料在确定东北地区大规模开发利用初始年限研究中的应用,并结合重分类、重心转移分析、叠加分析方法,分析了镇赉县地名志等史料记载的土地开发利用特征。结果表明:在康熙年间和1853年,镇赉县先后有过有记载的定居后小范围开垦活动,而直到1875年开始持续的土地开垦利用,此前镇赉县基本上处于自然状态。在技术手段不发达的早期,村屯的演变过程与土地开发利用过程是相辅相成的,因此,从村屯演变特征来看,1907-1912年期间土地开发利用最为突出;到1975年时,镇赉县村屯格局基本形成,而此时的土地开发利用活动已由个人行为转变为集体的机械化。在开禁等政策、自然灾害,以及战争等影响下,镇赉县土地开发呈由东部和中部的平坦地区向西部地势较高地区扩展的过程。  相似文献   

20.
六盘水市土壤侵蚀时空特征及影响因素分析   总被引：1，自引：0，他引：1  
六盘水市是我国生态地位极其重要,水土流失又较为严重的城市。近些年,六盘水市实施了一系列生态工程,为了定量分析六盘水市土壤侵蚀状况及其影响因素,本文基于RUSLE模型,利用降雨数据、遥感影像数据、土地利用数据等,对贵州省六盘水市1990-2015年土壤侵蚀模数和土壤侵蚀量进行定量模拟,分析其时空动态变化,利用地理探测器定量分析影响因素,并进行空间相关性分析,结果表明： ① 六盘水市土壤侵蚀以微度和中度侵蚀为主。土壤侵蚀严重地区主要分布在北盘江流域与南盘江流域交界处以及喀斯特山地地区,煤矿开采使植被覆盖等抑制土壤侵蚀因子减少作用,使局部地区土壤侵蚀程度加剧。② 1990-2010年平均土壤侵蚀模数整体为下降趋势,2010-2015年为上升趋势。其中2000年平均土壤侵蚀模数最大,2010年平均土壤侵蚀模数最小。该变化由降雨可蚀性因子和植被覆盖度因子综合影响所致。③ 植被覆盖度因子和多年平均降雨量因子是影响区域土壤侵蚀空间分布的重要因素。未利用土地、植被覆盖度小于0.3、坡度在25°以上和降雨量在1543~1593 mm之间的地区为高风险侵蚀区域。④ 植被覆盖度与土壤侵蚀在空间上全部呈负相关性,降雨因子与土壤侵蚀在空间上存在负相关性和正相关性。⑤ 土壤侵蚀改善区域大多分布在生态工程区域内,生态工程建设能够改善土壤侵蚀情况,不同生态工程保护侧重点不同导致土壤侵蚀改善程度不同。退耕还林还草工程对六盘水市土壤侵蚀的改善具有重要意义,六盘水市更宜退耕还林。  相似文献   

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