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1.
The temporal and spatial changes of NDVI on the Tibetan Plateau, as well as the relationship between NDVI and precipitation, were discussed in this paper, by using 8-km resolution multi-temporal NOAA AVHRR-NDVI data from 1982 to 1999. Monthly maximum NDVI and monthly rainfall were used to analyze the seasonal changes, and annual maximum NDVI, annual effective precipitation and growing season precipitation (from April to August) were used to discuss the interannual changes. The dynamic change of NDVI and the corre-lation coefficients between NDVI and rainfall were computed for each pixel. The results are as follows: (1) The NDVI reached the peak in growing season (from July to September) on the Tibetan Plateau. In the northern and western parts of the plateau, the growing season was very short (about two or three months); but in the southern, vegetation grew almost all the year round. The correlation of monthly maximum NDVI and monthly rainfall varied in different areas. It was weak in the western, northern and southern parts, but strong in the central and eastern parts. (2) The spatial distribution of NDVI interannual dynamic change was different too. The increase areas were mainly distributed in southern Tibet montane shrub-steppe zone, western part of western Sichuan-eastern Tibet montane coniferous forest zone, western part of northern slopes of Kunlun montane desert zone and southeastern part of southern slopes of Himalaya montane evergreen broad-leaved forest zone; the decrease areas were mainly distributed in the Qaidam montane desert zone, the western and northern parts of eastern Qinghai-Qilian montane steppe zone, southern Qinghai high cold meadow steppe zone and Ngari montane desert-steppe and desert zone. The spatial distribution of correlation coeffi-cient between annual effective rainfall and annual maximum NDVI was similar to the growing season rainfall and annual maximum NDVI, and there was good relationship between NDVI and rainfall in the meadow and grassland with medium vegetation cover, and the effect of rainfall on vegetation was small in the forest and desert area. 相似文献
2.
青藏高原植被覆盖变化与降水关系 总被引：15，自引：6，他引：9
The temporal and spatial changes of NDVI on the Tibetan Plateau, as well as the relationship between NDVI and precipitation, were discussed in this paper, by using 8-km resolution multi-temporal NOAA AVHRR-NDVI data from 1982 to 1999. Monthly maximum NDVI and monthly rainfall were used to analyze the seasonal changes, and annual maximum NDVI, annual effective precipitation and growing season precipitation (from April to August) were used to discuss the interannual changes. The dynamic change of NDVI and the corre- lation coefficients between NDVI and rainfall were computed for each pixel. The results are as follows: (1) The NDVI reached the peak in growing season (from July to September) on the Tibetan Plateau. In the northern and western parts of the plateau, the growing season was very short (about two or three months); but in the southern, vegetation grew almost all the year round. The correlation of monthly maximum NDVI and monthly rainfall varied in different areas. It was weak in the western, northern and southern parts, but strong in the central and eastern parts. (2) The spatial distribution of NDVI interannual dynamic change was different too. The increase areas were mainly distributed in southern Tibet montane shrub-steppe zone, western part of western Sichuan-eastern Tibet montane coniferous forest zone, western part of northern slopes of Kunlun montane desert zone and southeastern part of southern slopes of Himalaya montane evergreen broad-leaved forest zone; the decrease areas were mainly distributed in the Qaidam montane desert zone, the western and northern parts of eastern Qinghai-Qilian montane steppe zone, southern Qinghai high cold meadow steppe zone and Ngari montane desert-steppe and desert zone. The spatial distribution of correlation coeffi- cient between annual effective rainfall and annual maximum NDVI was similar to the growing season rainfall and annual maximum NDVI, and there was good relationship between NDVI and rainfall in the meadow and grassland with medium vegetation cover, and the effect of rainfall on vegetation was small in the forest and desert area. 相似文献
3.
1982~2013年青藏高原高寒草地覆盖变化及与气候之间的关系 总被引：7，自引：2，他引：5
利用GIMMS NDVI数据和地面气象站台观测数据,对青藏高原1982~2013年高寒草地覆盖时空变化及其对气象因素的响应进行研究,结果表明：青藏高原高寒草地生长季NDVI表现为从东南到西北逐渐减少的趋势,近32 a来,整个高原草地生长季NDVI呈上升趋势,增加速率为0.000 3/a (p<0.05);高寒草地生长季NDVI年际变化具有空间异质性,整体为增加趋势,呈增加趋势的面积约占研究区域面积的75.3%,其中显著增加的占26.0% （p<0.05）,类型主要为分布在青藏高原东北部地区的高寒草甸;比例为4.7%,草地类型主要为高寒草原,主要分布在高原西部地区;基于生态地理分区的分析显示,青藏高原草地与降水、温度的相关关系具有明显的空间差异,高寒草地生长季NDVI均值与降水呈显著正相关,对降水的滞后效应显著;高原东北部温度较高,热量条件较好,降水为高寒草地生长季NDVI变化的主导因子;东中部地区降水充沛,温度则为高寒草地生长的制约因子;南部地区降水和温度都较适宜,均与高寒草地生长季NDVI相关性显著(p< 0.05),共同作用于草地的生长;中部和西部地区,气候因子与高寒草地生长季NDVI关系均不显著。 相似文献
4.
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
5.
蒙古高原是中国重要的北方生态屏障。在全球气候变化的背景下,研究蒙古国植被物候变化特征对于认识蒙古国草地生态系统对气候变化的响应和促进区域畜牧业可持续发展具有重要意义。本研究利用非对称高斯拟合法对蒙古国2001—2019年MOD13Q1产品中的归一化植被指数（Normalized Differential Vegetation Index,NDVI）数据拟合,得到较为平滑的NDVI时间序列数据;基于TIMESAT平台,采用动态阈值法分析获得蒙古国连续19a植被物候数据。研究分析了蒙古国植被物候的空间分布及年际变化趋势,发现蒙古国植被返青期（Start of growing season,SOS）主要集中在110~150d,总体呈微弱推迟趋势,植被枯黄期（End of growing season,EOS）主要集中在270~310d,总体呈提前趋势,从而导致蒙古国生长季长度（Length of growing season,LOS）呈缩短趋势,且缩短时间最长可达2d以上。采用偏相关分析方法分析了植被物候对地形、降水、地表温度等地理要素的响应,表明蒙古国植被物候具有明显的空间异质性和海拔依赖性,不同植被物候对降水、地表温度（Land Surface Temperature,LST）的响应不同,SOS与日间LST呈显著正相关,EOS与夜间LST呈显著正相关,而LOS与年均降水呈显著负相关关系。 相似文献
6.
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
7.
近15a新疆不同类型植被NDVI时空动态变化及对气候变化的响应 总被引：4，自引：0，他引：4
为了研究新疆不同类型植被对气候变化的响应,以地带性划分的植被类型作为研究对象,1998-2012年为时间尺度,利用GIS的空间分析方法结合数学统计方法,分析了新疆各地带植被覆盖变化的时空分布特征;并采用"多元回归+残差插值"的方法,模拟了气温和降水量的空间分布;利用SPOT VGT/NDVI数据以及气候数据(气温和降水量数据),分析了5个不同地带植被的动态变化、年际变化和生长季内各月变化及其对气候变化的响应。结果表明:(1)新疆各地带植被覆盖度存在着显著差异,其中,温带北部草原地带高植被区和浓密植被区的范围较广,植被覆盖度较高,而高寒荒漠地带的极低植被区占该地带面积的一半以上,且植被覆盖度最低。(2)新疆各地带植被覆盖在近15 a间呈波动增加的趋势,5个地带的植被覆盖均有所改善,其中,高寒荒漠地带和暖温带半灌木、灌木地带的植被覆盖改善较为明显,其余3个地带均有少部分地区出现轻微改善现象。(3)温带半灌木、矮乔木荒漠地带,暖温带半灌木、灌木荒漠地带和温带半灌木、灌木荒漠地带4~10月的平均气温呈上升趋势,而温带北部草原地带、高寒荒漠地带对应的平均气温则出现下降趋势。5个地带的降水量在该时段内均表现为下降趋势。(4)基于年际尺度,新疆各地带植被NDVI与气温、降水量的相关性均不显著;基于月尺度,各地带植被NDVI受降水量的影响比气温大。同时,仅有暖温带半灌木、灌木荒漠地带植被NDVI与气温存在1个月的滞后性,其余4个地带对气温和降水均不存在滞后性。 相似文献
8.
1981-2010年气候变化和人类活动对内蒙古地区植被动态影响的定量研究 总被引：2，自引：1，他引：1
基于GIMMS NDVI以及MODIS NDVI数据,分析内蒙古地区1981-2010年的植被变化趋势,并结合气候、社会经济数据,以旗县为单位定量分析气候变化和人类活动对植被变化的影响,结果表明：①1981-2010年间,内蒙古地区植被变化具有典型的空间异质性,其中植被显著增加区域主要集中在西南部的阿拉善盟、鄂尔多斯市以及东部通辽市等地区,显著减少区域主要集中在北部的锡林郭勒盟以及东北部的呼伦贝尔市的部分地区;②对于植被显著增加区域,人类活动作用的影响面积最大,其次为气候因素,气候与人类活动的耦合作用也对植被增加有一定显著影响;内蒙古西部降雨量的增加、围封禁牧政策的实施以及农作物播种面积的增加为驱动植被增加的主要因素;③对于植被显著减少区域,人类活动的作用略大于气候因素;内蒙古中东部地区降雨减少以及近10年来部分旗县风速的增加是导致植被显著减少的重要气候因素;虽然人工造林、农作物播种面积会增加局部植被盖度,但在县域尺度不足以抵消干旱对植被生长的不利影响,反而会导致区域植被退化。 相似文献
9.
基于GIMMS 3g NDVI的近30年中国北部植被生长季始期变化研究 总被引：4，自引：0，他引：4
基于全球库存建模与绘图研究第三代归一化差值植被指数（GIMMS 3g NDVI）、土地利用和气温降水数据,利用NDVI时间序列谐波分析法(HANTS)重构了中国北部地区原始植被NDVI,用一元六次多项式拟合了植被生长曲线并结合逐像元动态阈值法提取了中国北部地区1983~2012年植被生长季始期并分析了其时空变化及对气温和降水的响应情况。结果表明：①GIMMS 3g NDVI具有较长的时序特征和较好的数据质量,经HANTS时间序列谐波分析后能很好的表现植被生长季曲线特征,可用于后续植被生长季的研究。② 北部地区生长季始期均值主要集中分布在80~150βd之间,全区30βa平均为111.6βd,东北平原、华北平原、河套平原、新疆天山和阿尔泰地区生长季始期早于其它区域。③ 研究时段内北部地区生长季始期总体上呈提前趋势（R2=0.19）,空间上由西北向东北逐渐推移,明显提前的区域主要分布在内蒙古中东部、东北平原、陕西南部和新疆天山的部分地区,明显推迟的区域主要分布在青藏高原高寒地区。④ 因植被类型的不同和区域的差异,生长季始期对气温和降水的响应程度不同,春季气温是影响生长季始期变化的主要自然因素。 相似文献
10.
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
11.
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
12.
2000—2017年内蒙古荒漠草原植被物候变化及对净初级生产力的影响 总被引：1，自引：1，他引：1
荒漠草原分布于干旱区和半干旱区,对气候变化的响应极为敏感,但目前学术界对于荒漠草原物候与生产力变化的研究仍较为薄弱。有鉴于此,论文采用2000—2017年MODIS NDVI数据和气象数据,利用通用数量化方法提取内蒙古荒漠草原植被的生长季始期(start of season, SOS)和生长季末期(end of season, EOS);基于Carnegie-Ames-Stanford Approach (CASA)模型估算了植被净初级生产力(NPP),并分析了植被物候和净初级生产力之间的关系。研究结果表明：① 2000—2017年内蒙古荒漠草原SOS呈显著提前趋势(0.88 d/a,P<0.05),EOS不显著提前(0.13 d/a,P>0.05),生长季长度(length of season, LOS)呈显著延长趋势(0.76 d/a)。81.53%像元的SOS与2—4月平均气温呈负相关(8.21%显著相关,P<0.05),60.80%像元的SOS与4月降水量呈负相关关系(6.12%显著相关,P<0.05);65.16%像元的EOS与9月平均气温呈负相关(5.03%显著相关,P<0.05),78.61%像元的EOS 与7—9月降水量呈正相关关系(10.12%显著相关,P<0.05)。② 内蒙古荒漠草原多年平均NPP为104.71 gC/(m 2·a),有自东向西逐渐降低的区域差异;在研究时段内,春、夏季和生长季的NPP均呈不显著增加趋势,秋季NPP有不显著减少趋势;生长季降水量增加有利于生长季NPP的积累。③ 春季NPP与SOS呈不显著负相关,秋季NPP与EOS呈显著正相关。LOS的延长促进了NPP的累积,其中生长季NPP与EOS的推迟关系更为密切。研究结果揭示气候变化对内蒙古荒漠草原植被物候和生产力有显著影响,对区域生态系统管理和生态建设具有重要参考意义。 相似文献
13.
Siqin Tong Jiquan Zhang Yuhai Bao Quan Lai Xiao Lian Na Li Yongbin Bao 《地理学报(英文版)》2018,28(5):595-610
This study analyzed the spatial and temporal variations in the Normalized Difference Vegetation Index (NDVI) on the Mongolian Plateau from 1982–2013 using Global Inventory Modeling and Mapping Studies (GIMMS) NDVI3g data and explored the effects of climate factors and human activities on vegetation. The results indicate that NDVI has slight upward trend in the Mongolian Plateau over the last 32 years. The area in which NDVI increased was much larger than that in which it decreased. Increased NDVI was primarily distributed in the southern part of the plateau, especially in the agro-pastoral ecotone of Inner Mongolia. Improvement in the vegetative cover is predicted for a larger area compared to that in which degradation is predicted based on Hurst exponent analysis. The NDVI-indicated vegetation growth in the Mongolian Plateau is a combined result of climate variations and human activities. Specifically, the precipitation has been the dominant factor and the recent human effort in protecting the ecological environments has left readily detectable imprints in the NDVI data series. 相似文献
14.
基于NOAA NDVI的植被生长季模拟方法研究 总被引：9，自引：0，他引：9
在近几年里, 大尺度的植被生长季监测已经成为全球气候变化研究中的一个重要科学问 题。NOAA/NDVI 数据为研究植被生长季时空变化规律提供了重要手段。文章综述并分析比较了 基于NDVI 估测植被生长季开始、结束、长度等特征参数的方法: NDVI 阈值、时间序列分析、物候 期的频率分布型与NDVI 相结合、主分量分析、利用曲线进行拟合等方法。受不同因素影响, 各方 法有不同的应用局限性, 因此, 在以前研究的基础上, 利用较常用的四种方法: 阈值法、滑动平均 法、最大变化斜率、曲线拟合模型模拟了锡林浩特1991～1999 年的草原生长季, 最后利用野外实 测的草原返青期验证了监测结果。结果表明: 与地面观测数据相结合, 基于阈值可得到较好的草 原返青期; 基于曲线拟合模型能适用于大尺度上的植被生长季变化监测, 但存在问题是拟合曲线 很难接近于实际曲线, 因此, 需要进一步研究的内容是选择合适的曲线估测模型, 监测不同植被 类型生长季的年际变化规律。 相似文献
15.
Though many studies have focused on the causes of shifts in trend of temperature, whether the response of vegetation growth to temperature has changed is still not very clear. In this study, we analyzed the spatial features of the trend changes of temperature during the growing season and the response of vegetation growth in China based on observed climatic data and the normalized difference vegetation index (NDVI) from 1984 to 2011. An obvious warming to cooling shift during growing season from the period 1984–1997 to the period 1998–2011 was identified in the northern and northeastern regions of China, whereas a totally converse shift was observed in the southern and western regions, suggesting large spatial heterogeneity of changes of the trend of growing season temperature throughout China. China as a whole, a significant positive relationship between vegetation growth and temperature during 1984 to 1997 has been greatly weakened during 1998–2011. This change of response of vegetation growth to temperature has also been confirmed by Granger causality test. On regional scales, obvious shifts in relationship between vegetation growth and temperature were identified in temperate desert region and rainforest region. Furthermore, by comprehensively analyzing of the relationship between NDVI and climate variables, an overall reduction of impacts of climate factors on vegetation growth was identified over China during recent years, indicating enhanced influences from human associated activities. 相似文献
16.
To examine the effects of interannual variations in environmental conditions on the seasonal range selection and movement pattern of Mongolian gazelles Procapra gutturosa, we compared the summer and winter ranges of satellite tracked gazelles among 3 years, and we analyzed the environmental conditions in the gazelles' seasonal ranges by using a satellite-derived normalized difference vegetation index (NDVI). The movement pattern of the tracked Mongolian gazelles was not regular migration between specific seasonal ranges. The locations of the summer ranges in 2003 and 2004 were similar for all gazelles, but in 2005, when the NDVI values were lower, the animals ranged about 30–70 km farther north, suggesting that the gazelles used areas of similar vegetation availability with former 2 years. The winter ranges were widely separated among years; the longest distance between winter ranges of the same individual in different years was about 340 km. During winter, the NDVI values of the winter ranges of tracked gazelles were almost always higher than or not significantly different from the mean of the 3-year range. Conservation strategies to allow access to wide ranges containing suitable areas in each year for gazelles, which location is changing interannually, are important. 相似文献
17.
中国草原区植被变化及其对气候变化的响应 总被引：4，自引：4，他引：0
利用1982~2006年GIMMS NDVI和气象数据,探究中国草原区植被变化及对气候的响应。结果表明,近25 a中国草原区植被覆盖总体呈上升趋势,但季节变化空间差异明显。春季温度对温带典型草原、高寒草甸草原和高寒典型草原植被生长有重要影响,而夏季和秋季温度同样对高寒草甸草原影响显著;夏季降水增多能明显促进夏季温带荒漠草原植被生长。除8月份以外,温带草原5~9月NDVI均与前一个月降水显著正相关;在生长季内,高寒草原NDVI与同期温度显著正相关,但8月份除外。此外高寒草原植被在生长最旺盛时期对降水变化存在1~3个月滞后期。 相似文献
18.
This paper used five years (2001-2006) time series of MODIS NDVI images with a 1-km spatial resolution to produce a land cover map of Qinghai Province in China. A classi-fication approach for different land cover types with special emphasis on vegetation, espe-cially on sparse vegetation, was developed which synthesized Decision Tree Classification, Supervised Classification and Unsupervised Classification. The spatial distribution and dy-namic change of vegetation cover in Qinghai from 2001 to 2006 were analyzed based on the land cover classification map and five grade elevation belts derived from Qinghai DEM. The result shows that vegetation cover in Qinghai in recent five years has been some improved and the area of vegetation was increased from 370,047 km2 in 2001 to 374,576 km2 in 2006. Meanwhile, vegetation cover ratio was increased by 0.63%. Vegetation cover ratio in high mountain belt is the largest (67.92%) among the five grade elevation belts in Qinghai Prov-ince. The second largest vegetation cover ratio is in middle mountain belt (61.80%). Next, in the order of the decreasing vegetation cover ratio, the remaining grades are extreme high mountain belt (38.98%), low mountain belt (25.55%) and flat region belt (15.46%). The area of middle density grassland in high mountain belt is the biggest (94,003 km2), and vegetation cover ratio of dense grassland in middle mountain belt is the highest (32.62%), and the in-creased area of dense grassland in high mountain belt is the greatest (1280 km2). In recent five years the conversion from sparse grass to middle density grass in high mountain belt has been the largest vegetation cover variation and the converted area is 15931 km2. 相似文献
19.
近5年青海省植被覆盖变化的遥感监测 总被引：3，自引：2，他引：1
This paper used five years （2001-2006） time series of MODIS NDVI images with a 1-km spatial resolution to produce a land cover map of Qinghai Province in China. A classification approach for different land cover types with special emphasis on vegetation, especially on sparse vegetation, was developed which synthesized Decision Tree Classification, Supervised Classification and Unsupervised Classification. The spatial distribution and dynamic change of vegetation cover in Qinghai from 2001 to 2006 were analyzed based on the land cover classification map and five grade elevation belts derived from Qinghai DEM. The result shows that vegetation cover in Qinghai in recent five years has been some improved and the area of vegetation was increased from 370,047 km^2 in 2001 to 374,576 km^2 in 2006. Meanwhile, vegetation cover ratio was increased by 0.63%. Vegetation cover ratio in high mountain belt is the largest （67.92%） among the five grade elevation belts in Qinghai Province. The second largest vegetation cover ratio is in middle mountain belt （61.80%）. Next, in the order of the decreasing vegetation cover ratio, the remaining grades are extreme high mountain belt （38.98%）, low mountain belt （25.55%） and flat region belt （15.46%）. The area of middle density grassland in high mountain belt is the biggest （94,003 km^2）, and vegetation cover ratio of dense grassland in middle mountain belt is the highest （32.62%）, and the increased area of dense grassland in high mountain belt is the greatest （1280 km^2）. In recent five years the conversion from sparse grass to middle density grass in high mountain belt has been the largest vegetation cover variation and the converted area is 15931 km^2. 相似文献
20.
冀北地区植被指数变化特征及影响因素分析 总被引：4，自引：1，他引：3
利用8km分辨率的NOVV/AVHRR NDV I数据、土地利用/覆被变化TM影像解译数据、气候数据、DEM数据和经济统计数据,对冀北地区1987~2000年植被覆被变化特征及影响因素进行了分析,得出主要结论如下:冀北地区土地覆被变化下NDVI平均增加值为0.35,变化特征为集中连片。土地利用变化导致NDVI平均减小值为0.17,变化特征呈斑块状离散分布。土地利用类型变化、错季蔬菜生产等人为因素对土地覆被变化下NDVI变化贡献率较低,降水、特别是生长季降水分布特征是影响NDVI变化的重要因素。 相似文献