| 近22年长江源区植被覆盖变化规律与成因 |
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| 引用本文： | 陈婷,梁四海,钱开铸,万力.近22年长江源区植被覆盖变化规律与成因[J].地学前缘,2008,15(6). |
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| 作者姓名： | 陈婷 梁四海 钱开铸 万力 |
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| 基金项目： | 国家自然科学基金重大研究计划中国西部环境和生态科学项目
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| 摘 要： | 利用GIMMS-NDVI遥感数据以及植被类型等专题信息,结合遥感图像处理以及地理信息系统技术,统计分析了1982—2003年长江源地区时间和空间上植被覆盖变化规律,并分析了植被覆盖变化的地形地貌因素与人为因素影响。结果表明:近22a,长江源植被覆盖呈总体增加趋势,而高寒草甸退化较严重,喜湿植被退化快于耐干旱植被,植被的生存环境趋于干旱化。研究结果表明,植被退化受到海拔、坡向、人类活动和地下水位的影响。海拔4400～4600m的较低海拔地带退化最强烈,主要为高寒草甸与高寒沼泽草甸受牧业影响较大;牧业影响半径为24km;道路的影响范围为24km,道路的修建加速了人类对高原植被的破坏作用;阳坡植被呈现趋于稳定和退化的趋势,阴坡植被表现为增长的趋势,降水量增加是源区植被,尤其是阴坡植被变好的重要原因,而太阳光照增强是导致阳坡干旱和植被趋于退化的潜在原因;近河床区地下水位埋深较浅,植被生长具有稳定的地下水源;在远离河床的一定区域内,地下水易于疏干,植被易于退化,河流影响范围为24km。
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| 关 键 词： | 长江源 植被指数 遥感 地理信息系统(GIS) |
Regularity and cause of vegetation coverage changes in the headwaters of the Changjiang Rive over the last 22years |
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| Chen Ting,Liang Sihai,Qian Kaizhu,Wan Li.Regularity and cause of vegetation coverage changes in the headwaters of the Changjiang Rive over the last 22years[J].Earth Science Frontiers,2008,15(6). |
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| Authors: | Chen Ting Liang Sihai Qian Kaizhu Wan Li |
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| Abstract: | In the study,we have statistically analyzed the spatial and temporal changes in vegetation cover in the headwaters of the Changjiang River from 1982 to 2003,as well as the causing factors,including both natural and artificial ones,by using remote sensing image processing and geographic information technology based on GIMMS(Global Inventory Modeling and Mapping Studies)-NDVI(Normalization Difference Vegetation Index)data and thematic vegetation information.Although the major trend of vegetation cover is rising through the recent 22 years,hygrophilous plants are gradually replaced by drought-enduring plants because of drought variations,which means the habitat of the vegetation is becoming dry.It is found out that the vegetation degradation is mainly influenced by the altitude,the aspect,the human activities and the groundwater level.The region in the altitude from 4400 to 4600 meters,which is mainly covered by alpine meadow and alpine swamp meadow,is strongly degraded by the stock raising with its influence radius of about 24 kilometers.The influence distance perpendicular to roads is also 24 kilometers,since road construction accelerates human-induced destruction to vegetation.Vegetation in shade aspect is rising due to the increase in precipitation,while vegetation in sunny aspect tends to be stable or degraded because of the enhancement in sunlight.Furthermore,the vegetation coverage is influenced by the groundwater level.In near riverbed fields,where the depth of groundwater is shallow,plants can easily grow;while in far riverbed fields,vegetation is prone to degrade due to drainage.The radius of river influence is 24 kilometers. |
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| Keywords: | headwater region of the Changjiang River vegetation index remote sensing Geographic Information System(GIS) |
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