共查询到20条相似文献，搜索用时 206 毫秒
1.
基于MODIS NDVI的内蒙古大青山自然保护区植被覆盖度的动态变化特征 总被引：2，自引：0，他引：2
以大青山自然保护区2000、2003、2006和2009年4个时相的MODIS归一化植被指数产品(MODIS NDVI)为数据源,对其进行大气辐射校正以及进行空间图像运算,生成大青山自然保护区不同时序的植被覆盖度图,结合当地气象水文等数据分析大青山自然保护区植被覆盖度的时空变化特征。结果表明:(1)2000年以来大青山自然保护区植被覆盖度有明显增加,除了低覆盖度植被面积显著减少外,其他覆盖度植被面积均有增加。其中,中低、中覆盖度植被增加面积更明显。(2)近10a来大青山自然保护区植被覆盖度整体呈上升趋势,从2003年43.5%增加到了2009年的49.5%。(3)与2000年相比,2009年核心区、缓冲区、实验区植被覆盖度分别增加了14.07%、14.32%和12.97%。保护区建立以来,植被覆盖度明显增加。 相似文献
2.
3.
利用MODIS-EVI月合成数据,计算2006—2015年石羊河中游生长季植被覆盖度,探究植被覆盖年际变化以及对气候的响应关系。利用像元二分模型计算植被覆盖度,提取研究区不同植被覆盖程度的年际变化。结果表明：10 a间,中游地区以低植被覆盖类型为主,并与同期降水的年际变化关系密切。其次,采用变化趋势分析法,计算监测时段内植被覆盖的动态变化。结果表明：中游地区生长季植被覆盖度总体上处于增加趋势,增加速率为0.041·（10a）^-1;植被覆盖度显著增加区域集中于绿洲-荒漠过渡带。最后,采用相关分析法,分析了植被覆盖度与生长季平均气温和降水的相关程度。生长季植被覆盖度与同期降水的相关程度高于与生长季平均气温相关性,平均偏相关系数分别为0.14和-0.05;荒漠绿洲过渡带成为与气候因子显著相关的活跃地带。 相似文献
4.
川藏铁路沿线植被覆盖度时空变化特征分析 总被引：2，自引：0，他引：2
基于MODIS-NDVI遥感数据反演了川藏铁路地区2000-2018年植被覆盖度,采用线性回归分析植被覆盖度的时空变化规律,利用相关分析法分析气候、地形等与植被覆盖度的相关关系。结果表明:(1)2000-2018年川藏铁路沿线平均植被覆盖度为0.629,呈现波动上升趋势,2000-2012年为缓慢增长,2013-2018年为快速增长。19年间植被覆盖度呈现好转的面积占比为53.78%,呈现下降面积占比5.25%,其中康定至昌都段上升率最大,巴宿至林芝段下降率最大。(2)川藏铁路沿线植被覆盖度空间上呈现东高西低的分布特征,2000-2018年成康、康林和拉林铁路段平均植被覆盖度依次为0.75、0.61和0.55,低海拔区域以中高、高植被覆盖度为主,高海拔区域以中低、低植被覆盖度为主。(3)相关分析表明,川藏铁路沿线植被覆盖度与温度(r2=0.376,p<0.01)和降雨量(r2=0.284,P<0.01)均为显著正相关,温度是驱动川藏铁路沿线植被覆盖度动态变化的主要气候因素,与海拔呈显著负相关(r2=-0.240,P<0.01)。 相似文献
5.
气候变化和人类活动对锡林郭勒草原植被覆盖度的影响 总被引：2，自引：0，他引：2
《干旱区研究》2021,(3)
基于遥感、气象及统计数据,采用线性趋势法和残差分析法,在不同时空尺度上监测1982—2018年锡林郭勒草原草地植被覆盖度动态,量化气候变化和人类活动对植被变化的贡献率。结果表明:1982—2018年,锡林郭勒草原植被覆盖度及变化具有明显的空间异质性,草甸草原覆盖度呈显著增加趋势(P0.01),荒漠草原覆盖度呈显著减少趋势(P0.01)。2000年为旗县草地覆盖度变化的主要节点。人类活动是锡林郭勒草原植被动态的主导因素,研究区多年人类活动因素的综合贡献率为65.06%。中东部和南部部分区域植被在人类积极作用下得到了显著改善,但西部和北部荒漠草原区的植被仍然呈现退化趋势。建议加大荒漠草原区生态政策实施力度以保障草地生态系统的可持续性。 相似文献
6.
石羊河中游生长季植被覆盖对气候的响应 总被引：1，自引：0，他引：1
利用MODIS-EVI月合成数据,计算2006—2015年石羊河中游生长季植被覆盖度,探究植被覆盖年际变化以及对气候的响应关系。利用像元二分模型计算植被覆盖度,提取研究区不同植被覆盖程度的年际变化。结果表明:10 a间,中游地区以低植被覆盖类型为主,并与同期降水的年际变化关系密切。其次,采用变化趋势分析法,计算监测时段内植被覆盖的动态变化。结果表明:中游地区生长季植被覆盖度总体上处于增加趋势,增加速率为0.041·(10a)~(-1);植被覆盖度显著增加区域集中于绿洲-荒漠过渡带。最后,采用相关分析法,分析了植被覆盖度与生长季平均气温和降水的相关程度。生长季植被覆盖度与同期降水的相关程度高于与生长季平均气温相关性,平均偏相关系数分别为0.14和-0.05;荒漠绿洲过渡带成为与气候因子显著相关的活跃地带。 相似文献
7.
陕西省退耕还林工程区植被覆盖度的变化分析 总被引：1，自引：0，他引：1
利用MODIS NDVI数据和像元二分模型计算的植被覆盖度,比较分析退耕还林工程区与周边区域、主要土地利用类型、不同坡度耕地植被覆盖度变化程度和趋势。结果表明：（1） 陕西省退耕还林区植被覆盖度从2000年到2011年呈现显著的增长趋势,增长速率高于周边区域;（2） 退耕还林区植被覆盖变化百分率≥10%的面积占79.8%,≤-10%所占面积不及1%;（3） 退耕还林区植被覆盖度显著增加的面积占其总面积的70.6%,显著减少的面积仅占0.1%,植被覆盖度显著增加的情况主要出现在未利用地、草地、林地和耕地,显著和极显著降低的发生在城乡、工矿、居民用地和极少部分耕地;（4） 坡耕地植被覆盖改善比例大,坡耕地植被覆盖改善对于耕地植被改善贡献较大。在陕西省气候呈现暖干化发展趋势背景下,退耕还林区植被覆盖度呈现显著增长趋势,增长速率高于周边区域,坡耕地、林地、草地均比其他类型有明显的增加,退耕还林政策实施区域取得了良好的植被恢复效果。 相似文献
8.
黄土高原水蚀风蚀交错带植被覆盖度动态变化 总被引：3，自引：0，他引：3
以GIMMS（global inventory modeling and mapping studies）归一化植被指数（normalized difference vegetation index,NDVI）为数据源,采用像元二分模型,提取1982-2006年黄土高原水蚀风蚀交错带不同时段（1982-1989年、1990-1999年、2000-2006年）的植被覆盖度,并运用转移矩阵模型,定量分析水蚀风蚀交错带植被覆盖变化情况。结果显示：研究区植被覆盖度整体呈增加趋势,时段间先增加后减少;从植被空间分布来看,中低植被覆盖度所占比重最大,其次为低植被覆盖和中植被覆盖类型,高植被覆盖度类型所占比例最小。总体来说,从时段1（1982-1989年）到时段3（2000-2006年）研究区植被是良性发展的,虽然局部环境有一定恶化,但整体环境仍呈改善趋势。分析发现,低覆盖度植被类型重心向西南方向移动,而中高覆盖度类型和高覆盖度类型重心向东移动,反映了黄土高原西南地区宁夏、甘肃中部受降雨减少和城市化等因素的影响,在近25 a植被受到了一定破坏,而中东部吴旗、志丹、安塞、延安等地及毛乌素沙地东胜附近近年来进行的退耕还林等一系列生态建设,产生了较好的效益。 相似文献
9.
近20 a来新疆植被覆盖变化特征研究 总被引：20，自引：6，他引：14
以前人提取的近20a(1982—2000年)植被覆盖度指数FVC为基础数据,根据新疆不同的自然地理区域和地貌类型,采用分区海拔的方法对FVC影像进行分类。对各地理区域植被的变化采用距平处理,初步定量分析了新疆植被的变化状况。结果表明,近20a来新疆无论是山地还是平原,高植被覆盖度的绿洲和森林面积均有所增加。以地区论,伊犁地区植被覆盖变化幅度最小,状况最为稳定;东疆地区绿洲与高覆盖度植被稳定,低覆盖度植被变化幅度相对较大;北疆平原地区绿洲面积增加,高覆盖度植被和无植被区面积减少;北疆山地森林植被增加,不同时间增加的速率不同,高覆盖度植被与森林的变化呈一定的相互转换关系;南疆地区绿洲面积显著增加,与此相对应的是高、中覆盖度草地的面积下降,山地荒漠面积近年来有所增加,森林和高覆盖度草地面积也有所增加。从植被类型转换方式来看,在平原区,绿洲与中、高覆盖度草地面积之间具有强烈负相关;而山区的植被类型转换多发生在无植被区与低、中覆盖度草地之间或高覆盖度草地和森林之间。人工绿洲面积的变化成为新疆平原区植被类型变化的重要因素,南北疆绿洲面积增加的同时,中、高覆盖度植被减少,即绿洲与沙漠之间过渡带的植被面积减少。 相似文献
10.
基于2000—2019年的林草植被覆盖度数据分析了河套灌区近20 a的林草植被时空变化特征,并利用地理探测器定量分析了各驱动因子对林草植被覆盖的影响。结果表明:(1)近20 a河套灌区林草地面积总体呈减少态势,减少量为966.15 km2,林草植被覆盖度等级整体呈上升趋势,多年平均林草植被覆盖度为28.3%,空间尺度上,河套灌区林草植被覆盖度呈现出东北向西南递减的空间变化特征;(2)近20 a低林草植被覆盖度、中林草植被覆盖度等重心主要位于永济灌域东北侧和义长灌域西南侧,各级林草植被覆盖重心表现为从东北向西南方向递减,并均呈现出向西南方向迁移的态势,各时段迁移距离介于0.71～15.46 km;(3)距水域距离、地下水埋深、气温、降水是影响区域内林草植被覆盖度的主导环境因子,且解释力分别为0.427、0.439、0.318、0.368;距水域距离、地下水埋深、年平均降水与其他因子的交互作用普遍较高,区域含水量的大小是影响河套灌区林草地生长状况的主要驱动力,研究结果可为灌区自然植被的保护与恢复提供相应的科学依据。 相似文献
11.
青海都兰绿洲-荒漠交错带植物特征值及多样性研究 总被引：1，自引：1，他引：0
采用样方调查法对察汗乌苏绿洲-荒漠交错带五个不同封育区植被的群落结构和特征值进行调查分析,并运用α-多样性指数(shannon-Wiener指数、Simpson指数、群落均匀度指数E)分析生物多样性变化.对比2008和2009年不同封育区植被盖度,密度,生物量等植物特征值表明,到2009年,2003年荒滩造林封育区、安... 相似文献
12.
Drought was a severe recurring phenomenon in Iraq over the past two decades due to climate change despite the fact that Iraq has been one of the most water-rich countries in the Middle East in the past.The Iraqi Kurdistan Region(IKR)is located in the north of Iraq,which has also suffered from extreme drought.In this study,the drought severity status in Sulaimaniyah Province,one of four provinces of the IKR,was investigated for the years from 1998 to 2017.Thus,Landsat time series dataset,including 40 images,were downloaded and used in this study.The Normalized Difference Vegetation Index(NDVI)and the Normalized Difference Water Index(NDWI)were utilized as spectral-based drought indices and the Standardized Precipitation Index(SPI)was employed as a meteorological-based drought index,to assess the drought severity and analyse the changes of vegetative cover and water bodies.The study area experienced precipitation deficiency and severe drought in 1999,2000,2008,2009,and 2012.Study findings also revealed a drop in the vegetative cover by 33.3%in the year 2000.Furthermore,the most significant shrinkage in water bodies was observed in the Lake Darbandikhan(LDK),which lost 40.5%of its total surface area in 2009.The statistical analyses revealed that precipitation was significantly positively correlated with the SPI and the surface area of the LDK(correlation coefficients of 0.92 and 0.72,respectively).The relationship between SPI and NDVI-based vegetation cover was positive but not significant.Low precipitation did not always correspond to vegetative drought;the delay of the effect of precipitation on NDVI was one year. 相似文献
13.
In this paper, we attempted to determine the most stable or unstable regions of vegetation cover in Mongolia and their spatio-temporal dynamics using Terra/MODIS Normalized Difference Vegetation Index(NDVI) dataset, which had a 250-m spatial resolution and comprised 6 periods of 16-day composited temporal resolution data(from 10 June to 13 September) for summer seasons from 2000 to 2012. We also used precipitation data as well as biomass data from 12 meteorological stations located in 4 largest natural zones of Mongolia. Our study showed that taiga and forest steppe zones had relatively stable vegetation cover because of forest characteristics and relatively high precipitation. The highest coefficient of variation(CV) of vegetation cover occurred frequently in the steppe and desert steppe zones, mainly depending on variation of precipitation. Our results showed that spatial and temporal variability in vegetation cover(NDVI or plant biomass) of Mongolia was highly dependent on the amount, distribution and CV of precipitation. This suggests that the lowest inter-annual CV of NDVI can occur during wet periods of growing season or in high precipitation regions, while the highest inter-annual CV of NDVI can occur during dry periods and in low precipitation regions. Although the desert zone received less precipitation than other natural zones of the country, it had relatively low variation compared to the steppe and desert steppe, which could be attributed to the very sparse vegetation in the desert. 相似文献
14.
文中应用2000～2011年期间的MODIS NDVI数据对比了山东半岛和辽东半岛植被覆盖的时间变化以及空间自相关特征。结果表明:山东半岛和辽东半岛植被覆盖状况均较好,其中辽东半岛植被覆盖相对更好;2000～2011年间两个半岛NDVI均呈显著上升趋势,山东半岛的上升趋势更明显。两半岛NDVI的全局Moran's I分别为0.896和0.778,均表现为正的全局空间自相关,植被覆盖均呈空间集聚状态,且山东半岛植被覆盖的集聚特征更突出。局部空间自相关上,山东半岛大部分地区,辽东半岛千山山脉以东和辽河流域的ND-VI表现为高-高自相关,这些区域植被覆盖较好;而山东半岛西北部的黄河三角洲湿地区域以及莱州湾,辽东半岛千山山脉以西和半岛南端大连市的NDVI呈低值区集聚状态,植被覆盖较差。总的来说,该研究有助于了解山东半岛和辽东半岛植被覆盖的空间聚集规律和关联模式,从而为认识研究区植被覆盖状况以及生态保护提供依据。 相似文献
15.
黑河中游植被覆盖率变化趋势及其驱动因子分析 总被引：2，自引：0，他引：2
利用2002~2011年的黑河干流中游归一化值被指数数据获得植被覆盖率变化趋势,选取合适的NDVI阈值将整个区域划分为"绿洲区"和"荒漠区",并分别探讨了地下水埋深、中游耗水量及累积降水量对两种区域面积和植被覆盖率变化的影响。结果表明:黑河干流中游植被覆盖率整体呈增长趋势,由2002年的32%增长到了2011年的36%,对植被覆盖率增长贡献最大的因素为绿洲区扩张,10年间绿洲区面积占比增长了10%;影响绿洲扩张的主要因素为地下水位埋深和中游耗水量,绿洲区植被覆盖率变化较小,可忽略其影响。荒漠区植被覆盖率的变化主要受累积降水量影响。利用地下水位埋深、中游耗水量、累积降水量可预测区域植被覆盖率的变化趋势,区分人类活动和气候变化对区域植被覆盖率的影响是可行的。 相似文献
16.
It is known that the exploitation of opencast coal mines has seriously damaged the environments in the semi-arid areas. Vegetation status can reliably reflect the ecological degeneration and restoration in the opencast mining areas in the semi-arid areas. Long-time series MODIS NDVI data are widely used to simulate the vegetation cover to reflect the disturbance and restoration of local ecosystems. In this study, both qualitative (linear regression method and coefficient of variation (CoV)) and quantitative (spatial buffer analysis, and change amplitude and the rate of change in the average NDVI) analyses were conducted to analyze the spatio-temporal dynamics of vegetation during 2000-2017 in Jungar Banner of Inner Mongolia Autonomous Region, China, at the large (Jungar Banner and three mine groups) and small (three types of functional areas: opencast coal mining excavation areas, reclamation areas and natural areas) scales. The results show that the rates of change in the average NDVI in the reclamation areas (20%-60%) and opencast coal mining excavation areas (10%-20%) were considerably higher than that in the natural areas (<7%). The vegetation in the reclamation areas experienced a trend of increase (3-5 a after reclamation)-decrease (the sixth year of reclamation)-stability. The vegetation in Jungar Banner has a spatial heterogeneity under the influences of mining and reclamation activities. The ratio of vegetation improvement area to vegetation degradation area in the west, southwest and east mine groups during 2000-2017 was 8:1, 20:1 and 33:1, respectively. The regions with the high CoV of NDVI above 0.45 were mainly distributed around the opencast coal mining excavation areas, and the regions with the CoV of NDVI above 0.25 were mostly located in areas with low (28.8%) and medium-low (10.2%) vegetation cover. The average disturbance distances of mining activities on vegetation in the three mine groups (west, southwest and east) were 800, 800 and 1000 m, respectively. The greater the scale of mining, the farther the disturbance distances of mining activities on vegetation. We conclude that vegetation reclamation will certainly compensate for the negative impacts of opencast coal mining activities on vegetation. Sufficient attention should be paid to the proportional allocation of plant species (herbs and shrubs) in the reclamation areas, and the restored vegetation in these areas needs to be protected for more than 6 a. Then, as the repair time increased, the vegetation condition of the reclamation areas would exceed that of the natural areas. 相似文献
17.
Effects of fencing on vegetation and soil restoration in a degraded alkaline grassland in northeast China 总被引：1，自引：0，他引：1
In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected area, whereas the grazed area was continuously grazed at 8.5 dry sheep equivalent（DSE）/hm2. In the current research, soil and plant samples were taken from grazed and fenced areas to examine changes in vegetation and soil properties in 2005, 2006 and 2008. Results showed that vegetation characteristics and soil properties improved significantly in the fenced area compared with the grazed area. In the protected area the vegetation cover, height and above- and belowground biomass increased significantly. Soil pH, electrical conductivity and bulk density decreased significantly, but soil organic carbon and total nitrogen concentration increased greatly in the protected area. By comparing the vegetation and soil characteristics with pre-degraded grassland, we found that vegetation can recover 6 years after fencing, and soil pH can be restored 8 years after fencing. However, the restoration of soil organic carbon, total nitrogen and total phosphorus concentrations needed 16, 30 and 19 years, respectively. It is recommended that the stocking rate should be reduced to 1/3 of the current carrying capacity, or that a grazing regime of 1-year of grazing followed by a 2-year rest is adopted to sustain the current status of vegetation and soil resources. However, if N fertilizer is applied, the rest period could be shortened, depending on the rate of application. 相似文献
18.
基于PSR模型对艾比湖流域生态系统健康评价研究 总被引：6，自引：0，他引：6
依据"压力-状态-响应"(PSR)模型,从压力、状态、响应三个层面建立艾比湖流域生态系统健康评价24个指标的评价体系。以艾比湖流域的相关数据为基础,用2000-2009年时间序列数据,分析艾比湖流域生态系统健康状况,运用综合评价及划分的等级标准对10年间艾比湖流域生态系统健康水平进行量化分析。评价结果表明:艾比湖流域生态系统在2000-2003年为较健康;在2004-2008年为一般病态,2009年为疾病。艾比湖流域生态系统健康状况总体不容乐观。 相似文献
19.
G GHEBREZGABHER Mihretab 《干旱区科学》2019,11(3):319-331
Remote sensing is an effective way in monitoring desertification dynamics in arid and semi-arid regions. In this study, we used a decision tree method based on NDVI(normalized difference vegetation index), SAVI(soil adjusted vegetation index), and vegetation cover proportion to quantify and analyze the desertification in Eritrea using Landsat data of the 1970 s, 1980 s and 2014. The results demonstrate that the NDVI value and the annual mean precipitation declined while the temperature increased over the past 40 a. Strongly desertified land increased from 4.82×10~4 km~2(38.5%) in the 1970 s to 8.38×10~4 km~2(66.9%) in 2014: approximately 85% of the land of the country was under serious desertification, which significantly occurred in arid and semi-arid lowlands of the country(eastern, northern, and western lowlands) with relatively scarce precipitation and high temperature. The non-desertified area, mostly located in the sub-humid eastern escarpment, also declined from approximately 2.1% to 0.5%. The study concludes that the desertification is a cause of serious land degradation in Eritrea and may link to climate changes, such as low and unpredictable precipitation, and prolonged drought. 相似文献
20.
The climatically sensitive Qinghai province of China has been recognized as a hotspot for studies on the feedbacks of terrestrial ecosystems to global climate change. Thus, investigating vegetation coverage and its natural drivers in Qinghai is an important focus of ecosystem research. On the basis of Moderate Resolution Imaging Spectroradiometer(MODIS) Enhanced Vegetation Index(EVI) time series data, we estimated the vegetation coverage in this region using the dimidiate pixel model. Trend analyses, correlations between meteorological parameters, changes in vegetation coverage, and the temporal and spatial relationships between soil texture and vegetation coverage were used to investigate the possible drivers of vegetation coverage variations. The results indicated that the reduction of vegetation coverage slowed down in the period from 2000 to 2012. Annual mean temperature was the main climatic driver of the total extremely low and low vegetation coverage areas in Qinghai, followed by the precipitation anomalies. The extremely low and low vegetation coverage areas were mainly distributed in regions with a mean annual relative air humidity of <40% and the spatial distributions of these two area types differentiated along the 200-mm rainfall contours. The total extremely low and low vegetation coverage areas were mainly characterized by sandy clay loam soil, followed by loamy sand and sandy soil. Regions with sandy loam or loam soil have the greatest risk of vegetation coverage reductions. Knowledge of vegetation coverage variation and its natural drivers in the ecologically fragile region of Qinghai can provide scientific support for managing environmental change and desertification. 相似文献