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1.
《地理学报(英文版)》2017,(7)
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
2.
《地理学报(英文版)》2017,(2)
Using the Integrated Biosphere Simulator, a dynamic vegetation model, this study initially simulated the net primary productivity(NPP) dynamics of China's potential vegetation in the past 55 years(1961–2015) and in the future 35 years(2016–2050). Then, taking the NPP of the potential vegetation in average climate conditions during 1986–2005 as the basis for evaluation, this study examined whether the potential vegetation adapts to climate change or not. Meanwhile, the degree of inadaptability was evaluated. Finally, the NPP vulnerability of the potential vegetation was evaluated by synthesizing the frequency and degrees of inadaptability to climate change. In the past 55 years, the NPP of desert ecosystems in the south of the Tianshan Mountains and grassland ecosystems in the north of China and in western Tibetan Plateau was prone to the effect of climate change. The NPP of most forest ecosystems was not prone to the influence of climate change. The low NPP vulnerability to climate change of the evergreen broad-leaved and coniferous forests was observed. Furthermore, the NPP of the desert ecosystems in the north of the Tianshan Mountains and grassland ecosystems in the central and eastern Tibetan Plateau also had low vulnerability to climate change. In the next 35 years, the NPP vulnerability to climate change would reduce the forest–steppe in the Songliao Plain, the deciduous broad-leaved forests in the warm temperate zone, and the alpine steppe in the central and western Tibetan Plateau. The NPP vulnerability would significantly increase of the temperate desert in the Junggar Basin and the alpine desert in the Kunlun Mountains. The NPP vulnerability of the subtropical evergreen broad-leaved forests would also increase. The area of the regions with increased vulnerability would account for 27.5% of China. 相似文献
3.
The Three-River Headwaters Region(TRHR), which is the source area of the Yangtze River, Yellow River, and Lancang River, is of key importance to the ecological security of China. Because of climate changes and human activities, ecological degradation occurred in this region. Therefore, "The nature reserve of Three-River Source Regions" was established, and "The project of ecological protection and construction for the Three-River Headwaters Nature Reserve" was implemented by the Chinese government. This study, based on MODIS-NDVI and climate data, aims to analyze the spatiotemporal changes in vegetation coverage and its driving factors in the TRHR between 2000 and 2011, from three dimensions. Linear regression, Hurst index analysis, and partial correlation analysis were employed. The results showed the following:(1) In the past 12 years(2000–2011), the NDVI of the study area increased, with a linear tendency being 1.2%/10a, of which the Yangtze and Yellow River source regions presented an increasing trend, while the Lancang River source region showed a decreasing trend.(2) Vegetation coverage presented an obvious spatial difference in the TRHR, and the NDVI frequency was featured by a bimodal structure.(3) The area with improved vegetation coverage was larger than the degraded area, being 64.06% and 35.94%, respectively during the study period, and presented an increasing trend in the north and a decreasing trend in the south.(4) The reverse characteristics of vegetation coverage change are significant. In the future, degradation trends will be mainly found in the Yangtze River Basin and to the north of the Yellow River, while areas with improving trends are mainly distributed in the Lancang River Basin.(5) The response of vegetation coverage to precipitation and potential evapotranspiration has a time lag, while there is no such lag in the case of temperature.(6) The increased vegetation coverage is mainly attributed to the warm-wet climate change and the implementation of the ecological protection project. 相似文献
4.
江河源区NDVI时空变化及其与气候因子的关系(英文) 总被引：5，自引：3，他引：2
The source regions of the Yangtze and Yellow rivers are important water conservation areas of China. In recent years, ecological deterioration trend of the source regions caused by global climate change and unreasonable resource development increased gradually. In this paper, the spatial distribution and dynamic change of vegetation cover in the source regions of the Yangtze and Yellow rivers are analyzed in recent 10 years based on 1-km resolution multitemporal SPOTVGT-DN data from 1998 to 2007. Meanwhile, the correlation relationships between air temperature, precipitation, shallow ground temperature and NDVI, which is 3×3 pixel at the center of Wudaoliang, Tuotuohe, Qumalai, Maduo, and Dari meteorological stations were analyzed. The results show that the NDVI values in these two source regions are increasing in recent 10 years. Spatial distribution of NDVI which was consistent with hydrothermal condition decreased from southeast to northwest of the source regions. NDVI with a value over 0.54 was mainly distributed in the southeastern source region of the Yellow River, and most NDVI values in the northwestern source region of the Yangtze River were less than 0.22. Spatial changing trend of NDVI has great difference and most parts in the source regions of the Yangtze and Yellow rivers witnessed indistinct change. The regions with marked increasing trend were mainly distributed on the south side of the Tongtian River, some part of Keqianqu, Tongtian, Chumaer, and Tuotuo rivers in the source region of the Yangtze River and Xingsuhai, and southern Dari county in the source region of the Yellow River. The regions with very marked increasing tendency were mainly distributed on the south side of Tongtian Rriver and sporadically distributed in hinterland of the source region of the Yangtze River. The north side of Tangula Range in the source region of the Yangtze River and Dari and Maduo counties in the source region of the Yellow River were areas in which NDVI changed with marked decreasing tendency. The NDVI change was980 Journal of Geographical Sciences positively correlated with average temperature, precipitation and shallow ground temperature. Shallow ground temperature had the greatest effect on NDVI change, and the second greatest factor influencing NDVI was average temperature. The correlation between NDVI and shallow ground temperature in the source regions of the Yangtze and Yellow rivers increased significantly with the depth of soil layer. 相似文献
5.
陕甘宁地区植被恢复对气候变化和人类活动的响应(英文) 总被引：5，自引：2，他引：3
The "Grain for Green Project" initiated by the governments since 1999 were the dominant contributors to the vegetation restoration in the agro-pastoral transitional zone of northern China. Climate change and human activities are responsible for the improvement and degradation to a certain degree. In order to monitor the vegetation variations and clarify the causes of rehabilitation in the Shaanxi-Gansu-Ningxia Region, this paper, based on the MODIS-NDVI and climate data during the period of 2000-2009, analyzes the main charac-teristics, spatial-temporal distribution and reasons of vegetation restoration, using methods of linear regression, the Hurst Exponent, standard deviation and other methods. Results are shown as follows. (1) From 2000 to 2009, the NDVI of the study area was improved progres-sively, with a linear tendency being 0.032/10a, faster than the growth of the Three-North Shelter Forest Program (0.007/10a) from 1982 to 2006. (2) The vegetation restoration is characterized by two fast-growing periods, with an "S-shaped" increasing curve. (3) The largest proportion of the contribution to vegetation restoration was observed in the slightly improved area, followed by the moderate and the significantly improved area; the degraded area is distributed sporadically over southern part of Ningxia Hui Autonomous Region as well as eastern Dingbian of Shaanxi province, Huanxian and Zhengyuan of Gansu province. (4) Climate change and human activities are two driving forces in vegetation restoration; more-over anthropogenic factors such as "Grain for Green Project" were the main causes leading to an increasing trend of NDVI on local scale. However, its influencing mechanism remains to be further investigated. (5) The Hurst Exponent of NDVI time series shows that the vegetation restoration was sustainable. It is expected that improvement in vegetation cover will expand to the most parts of the region. 相似文献
6.
The Qinling Mountains, located at the junction of warm temperate and subtropical zones, serve as the boundary between north and south China. Exploring the sensitivity of the response of vegetation there to hydrothermal dynamics elucidates the dynamics and mechanisms of the main vegetation types in the context of changes in temperature and moisture. Importance should be attached to changes in vegetation in different climate zones. To reveal the sensitivity and areal differentiation of vegetation responses to hydrothermal dynamics, the spatio-temporal variation characteristics of the normalized vegetation index(NDVI) and the standardized precipitation evapotranspiration index(SPEI) on the northern and southern slopes of the Qinling Mountains from 2000 to 2018 are explored using the meteorological data of 32 meteorological stations and the MODIS NDVI datasets. The results show that: 1) The overall vegetation coverage of the Qinling Mountains improved significantly from 2000 to 2018. The NDVI rise rate and area ratio on the southern slope were higher than those on the northern slope, and the vegetation on the southern slope improved more than that on the northern slope. The Qinling Mountains showed an insignificant humidification trend. The humidification rate and humidification area of the northern slope were greater than those on the southern slope. 2) Vegetation on the northern slope of the Qinling Mountains was more sensitive to hydrothermal dynamics than that on the southern slope. Vegetation was most sensitive to hydrothermal dynamics from March to June on the northern slope, and from March to May(spring) on the southern slope. The vegetation on the northern and southern slopes was mainly affected by hydrothermal dynamics on a scale of 3–7 months, responding weakly to hydrothermal dynamics on a scale of 11–12 months. 3) Some 90.34% of NDVI and SPEI was positively correlated in the Qinling Mountains. Spring humidification in most parts of the study area promoted the growth of vegetation all the year round. The sensitivity of vegetation responses to hydrothermal dynamics with increasing altitude increased first and then decreased. Elevations of 800 to 1200 m were the most sensitive range for vegetation response to hydrothermal dynamics. The sensitivity of the vegetation response at elevations of 1200–3000 m decreased with increasing altitude. As regards to vegetation type, grass was most sensitive to hydrothermal dynamics on both the northern and southern slopes of the Qinling Mountains; but most other vegetation types on the northern slope were more sensitive to hydrothermal dynamics than those on the southern slope. 相似文献
7.
To understand the variations in vegetation and their correlation with climate factors in the upper catchments of the Yellow River, China, Normalized Difference Vegetation Index(NDVI) time series data from 2000 to 2010 were collected based on the MOD13Q1 product. The coefficient of variation, Theil–Sen median trend analysis and the Mann–Kendall test were combined to investigate the volatility characteristic and trend characteristic of the vegetation. Climate data sets were then used to analyze the correlation between variations in vegetation and climate change. In terms of the temporal variations, the vegetation in this study area improved slightly from 2000 to 2010, although the volatility characteristic was larger in 2000–2005 than in 2006–2010. In terms of the spatial variation, vegetation which is relatively stable and has a significantly increasing trend accounts for the largest part of the study area. Its spatial distribution is highly correlated with altitude, which ranges from about 2000 to 3000 m in this area. Highly fluctuating vegetation and vegetation which showed a significantly decreasing trend were mostly distributed around the reservoirs and in the reaches of the river with hydropower developments. Vegetation with a relatively stable and significantly decreasing trend and vegetation with a highly fluctuating and significantly increasing trend are widely dispersed. With respect to the response of vegetation to climate change, about 20–30% of the vegetation has a significant correlation with climatic factors and the correlations in most areas are positive: regions with precipitation as the key influencing factor account for more than 10% of the area; regions with temperature as the key influencing factor account for less than 10% of the area; and regions with precipitation and temperature as the key influencing factors together account for about 5% of the total area. More than 70% of the vegetation has an insignificant correlation with climatic factors. 相似文献
8.
LIU Xianfeng ZHANG Jinshui ZHU Xiufang PAN Yaozhong LIU Yanxu ZHANG Donghai LIN Zhihui 《地理学报(英文版)》2014,24(2):288-302
The Three-River Headwaters Region （TRHR）, which is the source area of the Yangtze River, Yellow River, and Lancang River, is of key importance to the ecological secu- rity of China. Because of climate changes and human activities, ecological degradation oc- curred in this region. Therefore, ＂The nature reserve of Three-River Sou,＇ce Regions＂ was established, and ＂The project of ecological protection and construction for the Three-River Headwaters Nature Reserve＂ was implemented by the Chinese government. This study, based on MODIS-NDVI and climate data, aims to analyze the spatiotemporal changes in vegetation coverage and its driving factors in the TRHR between 2000 and 2011, from three dimensions. Linear regression, Hurst index analysis, and partial correlation analysis were employed. The results showed the following： （1） In the past 12 years （2000-2011）, the NDVI of the study area increased, with a linear tendency being 1.2%/10a, of which the Yangtze and Yellow River source regions presented an increasing trend, while the Lancang River source region showed a decreasing trend. （2） Vegetation coverage presented an obvious spatial difference in the TRHR, and the NDVI frequency was featured by a bimodal structure. （3） The area with improved vegetation coverage was larger than the degraded area, being 64.06% and 35.94%, respectively during the study period, and presented an increasing trend in the north and a decreasing trend in the south. （4） The reverse characteristics of vegetation cov- erage change are significant. In the future, degradation trends will be mainly found in the Yangtze River Basin and to the north of the Yellow River, while areas with improving trends are mainly distributed in the Lancang River Basin. （5） The response of vegetation coverage to precipitation and potential evapotranspiration has a time lag, while there is no such lag in the case of temperature. （6） The increased vegetation coverage is mainly attributed to the warm-wet climate change and the implementation of the ecological protection project. 相似文献
9.
Aboveground biomass in grasslands of the Qinghai-Tibet Plateau has displayed an overall increasing trend during 2003–2016, which is profoundly influenced by climate change. However, the responses of different biomes show large discrepancies, in both size and magnitude. By applying partial least squares regression, we calculated the correlation between peak aboveground biomass and mean monthly temperature and monthly total precipitation in the preceding 12 months for three different grassland types(alpine steppe, alpine meadow, and temperate steppe) on the central and eastern Qinghai-Tibet Plateau. The results showed that mean temperature in most preceding months was positively correlated with peak aboveground biomass of alpine meadow and alpine steppe, while mean temperature in the preceding October and February to June was significantly negatively correlated with peak aboveground biomass of temperate steppe. Precipitation in all months had a promoting effect on biomass of alpine meadow, but its correlations with biomass of alpine steppe and temperate steppe were inconsistent. It is worth noting that, in a warmer, wetter climate, peak aboveground biomass of alpine meadow would increase more than that of alpine steppe, while that of temperate steppe would decrease significantly, providing support for the hypothesis of conservative growth strategies by vegetation in stressed ecosystems. 相似文献
10.
Detecting the storage and change on topsoil organic carbon in grasslands of Inner Mongolia from 1980s to 2010s 总被引：2，自引：2，他引：0
Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon（SOC） storage is of great importance. Based on soil data from the second national soil survey and field survey during 2011–2012, by using the regression method between sampling soil data and remote sensing data, this paper aimed to investigate spatial distribution and changes of topsoil（0–20 cm） organic carbon storage in grasslands of Inner Mongolia between the 1980 s and 2010 s. The results showed that：（1） the SOC storage in grasslands of Inner Mongolia between the 1980 s and 2010 s was estimated to be 2.05 and 2.17 Pg C, with an average density of 3.48 and 3.69 kg C·m–2, respectively. The SOC storage was mainly distributed in the typical steppe and meadow steppe, which accounted for over 98% of the total SOC storage. The spatial distribution showed a decreased trend from the meadow steppe, typical steppe to the desert steppe, corresponding to the temperature and precipitation gradient.（2） SOC changes during 1982–2012 were estimated to be 0.12 Pg C, at 7.00 g C·m–2·yr–1, which didn＇t show a significant change, indicating that SOC storage in grasslands of Inner Mongolia remained relatively stable over this period. However, topsoil organic carbon showed different trends of carbon source/sink during the past three decades. Meadow steppe and typical steppe had sequestered 0.15 and 0.03 Pg C, respectively, served as a carbon sink; while desert steppe lost 0.06 Pg C, served as a carbon source. It appears that SOC storage in grassland ecosystem may respond differently to climate change, related to vegetation type, regional climate type and grazing intensity. These results might give advice to decision makers on adopting suitable countermeasures for sustainable grassland utilization and protection. 相似文献
11.
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
12.
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
13.
植被降水利用效率（PUE）是评价干旱、半干旱地区植被对降水响应的重要指标。利用1982—2015年GIMMS NDVI3g NDVI数据及同期气象数据反演内蒙古荒漠草原的PUE,研究荒漠草原不同植被类型、不同地区PUE时空变化,并分析了PUE 与气候因子的相关关系。结果表明：（1）1982—2015年间荒漠草原年均PUE为0.51 gC·m-2·mm-1,PUE的分布呈现出一定的空间异质性。荒漠草原PUE极显著增大和显著增大的面积分别占草原总面积的35.88%、55.41%,荒漠草原PUE极显著减小的面积占草原总面积的8.70%,荒漠草原PUE整体呈现增大趋势。（2）荒漠草原不同植被类型PUE均值范围0.34—0.56 gC·m-2·mm-1。各种植被类型中,东方针茅草原PUE最大,镰芒针茅草原PUE最小。除了镰芒针茅草原与其他植被类型差异显著以外,其他植被类型间差异不太显著。从PUE变化看,除了东方针茅草原PUE呈现下降趋势,其他植被类型PUE都呈现增大的趋势。（3）荒漠草原PUE与降水有很强的负相关性;草地年PUE与年均气温相关性不太明显;草地年PUE与年均太阳辐射呈正相关关系。 相似文献
14.
植被NDVI对城市扩展及气候变化的响应——以西安及其附近区域为例 总被引：1，自引：0，他引：1
植被 NDVI 对城市扩展及气候变化响应研究,对于科学评估区域生态环境变化及调整与约束人类活动具有重要理论和现实意义。以西安及其附近区域为例,基于区域土地利用、MODIS NDVI、气温和降水数据,分析了植被 NDVI 对城市扩展及气候变化的响应,结果表明：（1）2000-2014 年研究区植被 NDVI 变化过程划分为2000-2007 年的显著增加阶段和2007-2014 年的显著减少阶段,前者主要分布于区域北部黄土高原、南部秦岭北坡,后者主要分布于区域中部关中平原尤其是西安及其附近区域。（2）2000-2015 年研究区建设用地增加1 428.27 km2 ,建设用地增加区域植被 NDVI 呈显著减少趋势。（3）研究区植被 NDVI 与年降水量的相关性高于年平均气温,同时西安及其以南区域植被 NDVI 与年平均气温、年降水量均呈负相关关系,反映出城市扩展等人类活动对植被 NDVI 变化的影响超过了气候变化的影响。研究结果表明植被 NDVI 总体受气候变化控制,但局部受人类活动影响更为严重,并且植被 NDVI 对气候变化的响应表现出波动性,而对城市扩展表现出线性减少趋势性,为通过植被 NDVI 变化区分自然因素与人为因素对环境影响提供了可能。 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.
17.
青藏高原植被NDVI对气候因子响应的格兰杰效应分析 总被引：3，自引：1，他引：3
多变的气候和复杂的地理环境使得青藏高原植被对气候变化响应敏感,因此分析高原植被与气候因子之间的动态关系对气候变化研究和生态系统管理具有重要意义。论文基于1982—2012年青藏高原气象数据(气温、降水)以及GIMMS NDVI3g遥感数据,在像素级别上运用格兰杰因果关系检验方法,在月尺度和季节尺度上分析了高原植被NDVI(主要是草原)与平均气温、降水量之间的响应情况及因果关系。研究表明：① 月尺度上NDVI与平均气温之间、NDVI与降水量之间的时序平稳性比例高于季节尺度,月尺度下达到平稳性的植被区域分别占99.13%和98.68%,季节尺度下分别占64.01%和71.97%;② 月尺度下高原平均气温和降水量对NDVI影响的滞后期都集中在第12~13个月,荒漠草原、典型草原和草甸3种植被类型的滞后期一致,季节尺度下平均气温和降水量对NDVI影响的滞后期主要分布在第3~4和第6个季度,3种植被类型的滞后期差异性较大;③ 月尺度下,青藏高原约98.95%的植被覆被区的平均气温是引起NDVI变化的格兰杰原因,反之,大部分地区(约89.05%,除高原东南区域)内NDVI也是引起平均气温变化的格兰杰原因;季节尺度下,青藏高原中部以外植被区域(约92.03%)内的平均气温是引起NDVI变化的格兰杰原因,而在东部和西部部分地区(约50.55%)中NDVI也是引起平均气温变化的格兰杰原因;④ 月尺度下,高原东北和西北地区(约72.05%)内的降水量是引起NDVI变化的格兰杰原因,大部分地区(约94.86%,除东南部少量区域)中NDVI是引起降水量变化的格兰杰原因;季节尺度下,高原东南部(约61.43%)地区内的降水量是引起NDVI变化的格兰杰原因,高原中东部地区(约48.98%)中NDVI是引起降水量变化的格兰杰原因。总之,高原植被NDVI与气温、降水的相互作用显著,彼此均可构成格兰杰因果效应,但总体上气候因子的影响程度大于植被的反馈作用,月尺度的效应区域大于季节尺度的效应区域。 相似文献
18.
北方草原区主要群落类型表土花粉分析 总被引：38，自引：2，他引：36
建立花粉与现代植被的关系是利用地层沉积物中的花粉记录恢复古植被、古气候研究的基础工作之一。中国北方草原区39个表土花粉研究表明,蒿属、藜科是草原区花粉组合的主要成分,以禾本科为建群种的草原群落花粉组合以蒿属花粉为主,禾本科花粉多低于10%。禾本科花粉的低代表性可能与其分蘖繁殖、花粉产量低有关。草原区表土花粉浓度与植被盖度相关不明显。典型草原与荒漠草原花粉组合存在着明显的区别,典型草原区藜科花粉百分比一般低于25%,荒漠草原区一般高于25%。DCA分析表明,草原区针叶树、莎草科、石竹科花粉代表较湿润的环境,蒿、藜科、锦鸡儿、柽柳、白刺花粉代表较干燥的环境,阔叶树、禾本科、菊科、毛茛科、蓼科、豆科、唇形科(百里香)、虎榛子+榛、蔷薇科花粉代表的环境介于前两组之间。DCA分析用于草原区花粉组合研究具有较好的环境指示意义。 相似文献
19.
黄河流域植被覆盖度动态变化与降水的关系 总被引：64，自引：2，他引：64
利用8km分辨率Pathfinder NOAA-NDVI数据，对黄河流域1982－1999年地表植被覆盖的空间分布及时间序列变化进行了分析，并通过计算不同时段降水量与年最大NDVI之间的相关系数分析了降水对流域植被覆盖的影响。结果发现近20年来黄河流域平均植被覆盖度有增加趋势，但青藏高原上有所减小；汛期降水量的多少对地表植被覆盖度的年际变化起主要作用，其中草原地区影响最显著，而在森林植被区及部分灌溉农作区，降水的年际变化对地表覆盖的影响比较小。 相似文献
20.
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