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1.
GIMMS NDVI database and geo-statistics were used to depict the spatial distribution and temporal stability of NDVI on the Mongolian Plateau.The results demonstrated that:(1) Regions of interest with high NDVI indices were distributed primarily in forested mountainous regions of the east and the north,areas with low NDVI indices were primarily distributed in the Gobi desert regions of the west and the southwest,and areas with moderate NDVI values were mainly distributed in a middle steppe strap from northwest to southeast.(2) The maximum NDVI values maintained for the past 22 years showed little variation.The average NDVI variance coefficient for the 22-year period was 15.2%.(3) NDVI distribution and vegetation cover showed spatial autocorrelations on a global scale.NDVI patterns from the vegetation cover also demonstrated anisotropy;a higher positive spatial correlation was indicated in a NW-SE direction,which suggested that vegetation cover in a NW-SE direction maintained increased integrity,and vegetation assemblage was mainly distributed in the same specific direction.(4) The NDVI spatial distribution was mainly controlled by structural factors,88.7% of the total spatial variation was influenced by structural and 11.3% by random factors.And the global autocorrelation distance was 1178 km,and the average vegetation patch length(NW-SE) to width(NE-SW) ratio was approximately 2.4:1.0. 相似文献
2.
基于16 d合成MODIS NDVI数据提取的时间序列植被覆盖度数据,采用一元线性回归趋势分析,对黄土高原2000-2008年植被覆盖度的时空变化及其地形分异、土地利用/覆被变化的影响进行了定量分析。结果表明：（1）研究时段黄土高原植被覆盖度整体呈快速上升趋势,局部下降;（2）黄土高原植被覆盖度变化存在明显的地形分异,陡坡等植被恢复、重建和保育的主要区域植被覆盖度增速显著;（3）土地利用/覆被变化对植被覆盖度的增加影响突出,土地利用/覆被类型变更区植被覆盖度增速显著高于未变化区域,退耕还林还草区增速尤其突出;（4）土地利用/覆被类型未变化区域植被覆盖度总体上也呈增加趋势,但因植被覆盖度水平相对较高,增速明显低于土地利用/覆被类型变化区。上述结果表明,黄土高原植被保育、植被恢复和重建在植被覆盖度提升方面取得了明显成效。 相似文献
3.
气候和土地利用变化对塔里木河干流区植被覆盖变化的影响 总被引：4，自引：0，他引：4
基于遥感和地理信息系统技术,利用1998—2008年SPOT-VEGETATION归一化植被指数（NDVI）数据对塔里木河干流区1998—2007年植被覆盖的时空变化进行了监测,并从气候变化和土地利用变化双重角度分析了植被覆盖变化的原因。研究表明,塔里木河干流区植被覆盖变化经历了两个阶段:1998—2001年植被覆盖严重退化时期;2002—2007年植被覆盖度由急剧上升到缓慢下降再到持续升高时期,NDVI明显高于20世纪末期水平。塔里木河干流区植被覆盖变化存在显著的空间差异,绿洲农业灌溉区和退耕还林还草生态恢复区的植被覆盖度显著提高,天然草地植被区的植被退化严重。塔里木河干流区植被覆盖变化是气候和土地利用变化共同作用的结果。温度对植被覆盖变化的影响表现为对植被生长年内韵律的控制和秋季植被生长期的延长,年降水量的波动式上升是导致塔里木河干流区植被覆盖变化两个阶段呈现差异的主导因素。 相似文献
4.
蒙古高原NDVI的空间格局及分异 总被引：5，自引：2，他引：3
GIMMS NDVI database and geo-statistics were used to depict the spatial distribu-tion and temporal stability of NDVI on the Mongolian Plateau. The results demonstrated that: (1) Regions of interest with high NDVI indices were distributed primarily in forested moun-tainous regions of the east and the north, areas with low NDVI indices were primarily distrib-uted in the Gobi desert regions of the west and the southwest, and areas with moderate NDVI values were mainly distributed in a middle steppe strap from northwest to southeast. (2) The maximum NDVI values maintained for the past 22 years showed little variation. The average NDVI variance coefficient for the 22-year period was 15.2%. (3) NDVI distribution and vege-tation cover showed spatial autocorrelations on a global scale. NDVI patterns from the vegetation cover also demonstrated anisotropy; a higher positive spatial correlation was in-dicated in a NW-SE direction, which suggested that vegetation cover in a NW-SE direction maintained increased integrity, and vegetation assemblage was mainly distributed in the same specific direction. (4) The NDVl spatial distribution was mainly controlled by structural factors, 88.7% of the total spatial variation was influenced by structural and 11.3% by random factors. And the global autocorrelation distance was 1178 km, and the average vegetation patch length (NW-SE) to width (NE-SW) ratio was approximately 2.4:1.0. 相似文献
5.
This research investigates the recent distribution variation trends of vegetation in the Tibet region using Normalized Difference Vegetation Index (NDVI) data from 2000 to 2007. It also discusses the causes of vegetation degradation in typical regions (such as Nagqu) based on climatic conditions, human activity, and other influencing factors. Results show that the areas with the best vegetation cover are in Nyingchi and the southern part of Shannan, followed by Chamdo, the Lhasa area, and the eastern part of Nagqu. Vegetation in various regions exhibits significant seasonal differences. The vegetation status has improved in some parts of the Tibet region in the past few years, while the areas with the most serious degradation are in the middle and southern parts of the Nagqu region. On average, distinct vegetation degradation occurred between 2003 and 2006 in the whole Tibet region but vegetation has been increasing since 2006. The vegetation cover in summer basically determines the annual vegetation status. An increase in precipitation and decrease in wind speed generally corresponds to an increase in vegetation cover. The reverse is also true: a decrease in precipitation and increase in wind speed correspond to the decrease in vegetation cover. NDVI is thus positively related to temperature and precipitation but has a negative relation with wind speed. Increasing temperature and decreasing precipitation have led to the present vegetation degradation in Nagqu, and vegetation in all of these regions has been affected by growth of human population, intensified urbanization, livestock overgrazing leading to the proliferation of noxious plants, extraction of underground minerals and alluvial gold, extensive harvesting of traditional Chinese medicinal plants [e.g., Cordyceps sinensis, Caladium spp., and saffron crocus (Crocus sativus)], and serious rodent and other pest damage. 相似文献
6.
基于SPOTNDVI的华北北部地表植被覆盖变化趋势 总被引：16，自引：2，他引：14
为分析华北北部地表植被覆盖变化趋势,探寻合理土地利用方式,基于1999年1月至2006年12月的SPOT-VEGETATION逐旬NDVI数据,采用国际通用的MVC(最大合成法)获得月NDVI值,用均值法求出年均NDVI数值。在此基础上,用一元线性回归斜率定量描述地表覆盖动态变化,以Hurst指数表示其时间依存性,利用GIS工具表征其空间格局并进行空间统计分析。研究结果表明:近8年来华北北部地表植被覆盖整体得到改善的区域比植被覆盖退化的区域面积大,得到改善的区域约占总面积的66.04%,基本不变的区域约占14.39%,退化区域约占19.57%。各种土地利用类型Hurst指数平均值均为0.5 相似文献
7.
Douglas Stow Allen Hope William Boynton Stuart Phinn Donald Walker Nancy Auerbach 《Geomorphology》1998,21(3-4)
The spatial variability and co-variability of two different types of remote sensing derivatives that portray vegetation and geomorphic patterns are analyzed in the context of estimating regional-scale CO2 flux from land surfaces in the arctic tundra. For a study area encompassing the Kuparuk River watershed of the North Slope of Alaska, we compare satellite-derived maps of the normalized difference vegetation index (NDVI) generated at two different spatial resolutions to a map of vegetation types derived by image classification of data from the Landsat multispectral scanner (MSS). Mean values of NDVI for each cover type stratum are unique (with the exception of moist acidic tundra and shrubland types). Based on analysis of semi-variograms generated for SPOT-NDVI data, most of the vegetation cover and landform features of this arctic tundra landscape have spatial dimensions of less than 1 km. Thaw lakes on the coastal plain and glacial depositional landforms, such as moraines in the foothills, seem to be the largest features, with vegetation units having dimensions no larger than 700 m. Frequency distributions of NDVI and vegetation types extracted for sampling transects flown by an aircraft sensing CO2 flux, relative to distributions for the entire Kuparuk River watershed, suggest a slight sampling bias towards greater cover of mesic wet sedge tundra and thaw lakes and associated lower NDVI values. The regional pattern of NDVI for the North Slope of Alaska corresponds primarily to differences between the two major physiographic provinces of this region. 相似文献
8.
In Northeast Thailand, the climate change has resulted in erratic rainfall and tem- perature patterns. The region has experienced both periods of drought and seasonal floods with the increasing severity. This study investigated the seasonal variation of vegetation greenness based on the Normalized Difference Vegetation Index （NDVI） in major land cover types in the region. An assessment of the relationship between climate patterns and vegeta- tion conditions observed from NDVI was made. NDVI data were collected from year 2001 to 2009 using multi-temporal Terra MODIS Vegetation Indices Product （MOD13Q1）. NDVI pro- files were developed to measure vegetation dynamics and variation according to land cover types. Meteorological information, i.e. rainfall and temperature, for a 30 year time span from 1980 to 2009 was analyzed for their patterns. Furthermore, the data taken from the period of 2001-2009, were digitally encoded into GIS database and the spatial patterns of monthly rainfall and temperature maps were generated based on kriging technique. The results showed a decreasing trend in NDVI values for both deciduous and evergreen forests. The highest productivity and biomass were observed in dry evergreen forests and the lowest in paddy fields. Temperature was found to be increasing slightly from 1980 to 2009 while no significant trends in rainfall amounts were observed. In dry evergreen forest, NDVI was not correlated with rainfall but was significant negatively correlated with temperature. These re- sults indicated that the overall productivity in dry evergreen forest was affected by increasing temperatures. A vegetation greenness model was developed from correlations between NDVI and meteorological data using linear regression. The model could be used to observe the change in vegetation greenness and dynamics affected by temperature and rainfall. 相似文献
9.
基于DEM的地形湿度指数及其应用研究进展 总被引：15，自引：4，他引：11
地形湿度指数以数字高程模型（DEM）为基础,综合考虑了地形和土壤特性对土壤水分分布的影响,在流域土壤水分空间分布的研究中具有重要的理论与应用价值。根据对汇流面积时空变化的分析,地形湿度指数可分为静态、半动态和动态地形湿度指数等类型。在利用该指数评价土壤水分空间分布状况时,需要考虑计算方法与DEM网格单元大小的影响及其普遍适应性等问题。同时,针对黄土高原干旱半干旱区实际的水分循环过程和产流机制与现有地形湿度指数假设条件的差异,提出了地形湿度指数在黄土高原地区的研究设想与应用途径,以期为该区的水土保持和植被恢复研究提供理论和实践支持。 相似文献
10.
青藏高原中东部植被覆盖对水热条件的响应研究 总被引：3，自引：1，他引：2
植被覆盖的变化常是自然因子和人类活动的综合作用,分析植被对水热条件的响应关系有助于认识人类活动在地表植被变化中的作用程度。本文旨在结合1982~2000年地面气象观测资料和NOAA卫星的AVHRR 植被指数（8km）,对气象站点分布相对密集的青藏高原中东部的NDVI（归一化植被指数）空间变化同水热条件的响应关系进行分析。通过水热有关指标的趋势面模拟、植被类型比较和样带分析,表明：在青藏高原中东部地区,水热条件组合较好（如常绿针叶林）或较差（如荒漠半荒漠）的区域,多年平均的NDVI旬值同水热条件的相关性不强;而范围广阔的水热条件组合中等区域（如高山草甸/草原）同水热条件相关性很高;青藏高原周边区域植被对水热条件相对不敏感,而高原主体部分植被覆盖同水热的相关性则很高（0.75以上）;此外,海拔对热量条件影响很大,进而影响植被覆盖。 相似文献
11.
近10年蒙古高原植被覆盖变化及其对气候的季节响应 总被引：8，自引：0，他引：8
利用2001~2010年间MODIS NDVI数据、同期气象数据和MODIS土地覆盖分类产品,探讨蒙古高原植被覆盖变化趋势及其对气温和降水量的季节响应特征。结果表明,10 a来,蒙古高原植被覆盖度呈增加趋势和呈下降趋势的面积基本持平;春季和夏季植被覆盖度呈下降趋势,而秋季呈上升趋势,降水量是最主要的影响因子;在秋季5种植被类型均呈增加趋势,而在春季和夏季不同植被类型的增减趋势因植被类型而异。 相似文献
12.
北部湾海岸带植被覆盖时空动态特征及未来趋势 总被引：1，自引：0，他引：1
分析北部湾海岸带植被覆盖动态变化趋势,能为开展海岸带植被生态环境监测提供决策。以2000―2011年SPOT-VEGETATION逐旬NDVI数据为基础,采用MVC（最大值合成法）、标准差、线性趋势分析（SLOPE）和Hurst指数等数理统计方法对研究区植被覆盖时空变化特征及未来趋势进行定量分析。结果表明：1）研究区植被覆盖整体上处于变好的状态,在年尺度上呈现出“波动―明显改善”的趋势,且海岸带东岸与西岸的植被变化趋势快于丘陵地区;在季节尺度上NDVI的增长速率为：秋季＞夏季＞春季＞冬季;在月尺度上NDVI在6―11月植被生长迅速,而在1―4月则生长缓慢;2）NDVI均值的空间分布规律自东北―西南中心线呈现出“两头高、中心地带低”的趋势,且NDVI均值自西向东的变化规律为-0.026/1N°,具有经向地带性特点;3）NDVI的Hurst指数值为0.306 5~0.995 3,平均值为0.777 4,反持续性序列（15.78%）＜持续性序列（84.22%）,未来总体植被覆盖呈现出持续性改善趋势。未来需要重点进行保护的植被区域主要集中在十万大山的西南部、钦江流域的上游以及合浦县的西南部。 相似文献
13.
基于SPOT VEGETATION数据的中国西北植被覆盖变化分析 总被引：66，自引：16，他引：66
基于遥感和地理信息系统的技术,利用SPOT-VEGETATION NDVI(Normalized Difference Vegetation Index)数据对我国西部地区植被覆盖的情况进行了动态监测。采用MVC（Maximum Value Composites）、一元线性回归趋势分析和变化幅度百分比等方法分析西部地区植被变化特征,并结合西北五省土地利用类型图,分析不同植被类型的年最大化NDVI(MNDVI)变化趋势及特点。其结果是:近7 a来植被覆盖存在普遍退化的趋势,且2000-2001与2001-2002年度的变化幅度较大。在局部区域植被有改善的趋势, 但总的改善幅度小于退化幅度。分析结果表明, 植被改善的区域主要分布在陕西和宁夏的大部分地区以及新疆西北部和西南部地区。大部分地区植被退化。而且不同植被的MNDVI在相同的年份表现出相似的变化特点和趋势。 相似文献
14.
额尔齐斯河流域中亚段植被覆盖遥感动态监测 总被引：1，自引：1，他引：0
利用中亚北部额尔齐斯河流域2000-2008年的中分辨率成像光谱仪(Moderate ResolutionImaging Spectrometer,MOD IS)数据,分析了额尔齐斯河中亚段不同区域的归一化植被指数(Nor-malized D ifference Vegetation Index,NDVI)随季节变化的规律,并合成全年最大NDVI值代表当年植被最好时期的NDVI值,应用混合像元分解模型,计算研究区内的植被覆盖度并根据植被覆盖度的高低将研究区内的植被覆盖程度分为六个等级:无覆盖、极低覆盖度、低覆盖度、中覆盖度、中高覆盖度和高覆盖度。通过研究区内植被覆盖度的变化情况在一定程度上揭示研究区内植被变化情况。2000-2003年,研究区的植被覆盖水平有降低趋势,2003-2007年呈增加趋势,2007覆盖水平与2002年相近,2008年覆盖水平降低明显,为9 a来最低,是由研究区当年降水量减少引起;植被覆盖水平高的区域主要分布在研究区东北部的山区和西北部的平原区,植被覆盖水平较低的区域集中在流域中西部的干旱草原;高覆盖区域的植被覆盖年际变化幅度较中低覆盖区域的小。 相似文献
15.
16.
为科学认识喀斯特山区植被变化及其地形效应,基于MODIS NDVI数据,采用统计学方法,系统分析2000-2016年喀斯特山区植被变化的时空特征及其与海拔、地形起伏度、坡度、坡向的关系。研究表明,黔桂喀斯特山区植被绿度中部高,西北及东南较低,年均NDVI随海拔和地形起伏度的增加呈单峰曲线变化,峰值位于400~600 m,NDVI随坡度和坡向的变化不明显;2000-2016年大部分地区NDVI呈增长趋势,其中超过20%的地区呈显著增长（P<0.05）,年均增长率约0.0018。西部和东南部绿化趋势最为显著,仅在东北和中东部,NDVI呈下降趋势;NDVI呈增长趋势的比例随海拔的增加而增加,说明该喀斯特山区近年来植被恢复向着良性化方向发展,高海拔植被恢复速率更快,低海拔缓坡处的植被生态建设需要进一步加强。 相似文献
17.
自然因子对四川植被NDVI变化的地理探测 总被引：11，自引：0，他引：11
许多研究已表明基于遥感的植被指数在地表过程和全球变化研究中具有重要作用,对认识植被变化的驱动因素具有重要意义,但自然因子对植被变化影响仍然难以量化。应用地理探测器模型,研究四川地区自然因子变化对植被分布的空间模式和植被变化的交互影响,并确定了促进植被生长的各主要自然因子最适宜特征。结果表明：① 2000-2015年,四川植被覆盖度状况良好,中高、高植被覆盖面积之和均超过94%;归一化植被指数（NDVI）转化表现为NDVI > 0.4以上区域转化明显,中高和高植被覆盖区面积分别呈显著下降和上升趋势;植被覆盖时空变化差异显著,植被覆盖较高区域位于四川盆地东北部、川西北高原地区,植被覆盖较低区域分布于四川盆地中部城市密集区域。② 土壤类型、高程和年均温度变化等因子较好地解释了植被状况的可变性。③ 自然因子对植被NDVI影响存在交互作用,自然因子协同效应呈现相互增强和非线性增强关系,两种因子交互作用增强了单因子的影响。④ 研究揭示的促进植被生长的各主要因子最适宜特征,有助于更好地理解自然因素对植被NDVI变化的影响及其驱动机制。 相似文献
18.
Bair Z. TSYDYPOV Endon Zh. GARMAEV Arnold K. TULOKHONOV Eduard A. BATOTSYRENOV Alexander A. AYURZHANAEV Zhargalma B. ALYMBAEVA Ts. CHIMEDDORJ 《资源与生态学报(英文版)》2015,6(2):73-78
本文选择蒙古中部地区的两个模型多边形对植被多样性进行调查研究。它们都位于干旱、半干旱少雨地区。基于Landsat TM影像,本文研究了多边形区域的NDVI随时间变化的多时相NDVI值制图,得到所选择的具备不同值NDVI区域的全尺度景观特征。这一特征在对耐旱环境组的植被分析中得到了证实。该过程中将近整个实验多边形区域的植被偏离得到了追踪。NDVI的时间分布分析呈现出数值的降低,这说明了在戈壁,稀疏植被存在耐旱趋势。在半干旱气候区域中偏离植被趋势与牧草地的重载负直接相关。 相似文献
19.
藏西南高原植被覆盖时空变化及其与气候因素和人类活动的关系 总被引：1，自引：0，他引：1
研究基于MODIS-NDVI数据和气象数据,利用趋势分析、相关分析及残差分析等方法,分析了2000―2020年藏西南高原植被NDVI在不同时段的时空变化特征及气候因素和人类活动对植被NDVI的影响,结果表明：近20 a来藏西南高原植被NDVI呈增加趋势,不同时段植被NDVI增长速率存在显著差异,主要表现为秋季>生长季>夏季>全年>春季>冬季;不同时段植被NDVI的分布格局虽存在差异,但高原东部植被覆盖度明显高于西部地区;高原大部分区域植被状态基本稳定,局部明显改善,部分区域有所退化;年际尺度上,气温和降水的增加导致植被NDVI升高,季节尺度上,春季、秋季和冬季气温升高导致植被NDVI升高,降水的增加导致植被NDVI下降,夏季和生长季气温升高导致植被NDVI下降,降水升高导致植被NDVI增加;人类活动对高原大部分区域呈正面影响,局部地区呈负面影响,集中分布在半农半牧和纯牧业县区。 相似文献