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1.
流域植被覆盖状况对于水源地生态环境保护具有重要的指示作用.当前的水质目标管理不仅要着眼于湖库水质参数控制,更应该从整个流域的角度维系生态平衡.在此背景下,依托长时间序列MODIS遥感数据对千岛湖流域2001-2013年植被覆盖状况进行监测,采用最小二乘法趋势分析和Mann-Kendall显著性检验方法分析了千岛湖流域植被的空间分布特征、时间变化特征与长期变化趋势.研究表明该方法能够有效地监测流域植被覆盖的时空动态变化:1)从空间分布上来看,千岛湖流域植被覆盖状况整体较好,但同时也发现受人为干扰较大的地域如河、湖附近的城镇建设用地、农业用地以及园地,其NDVI值明显低于自然林地;2)从时间变化特征上看,2001-2013年千岛湖流域植被年际NDVI在0.69~0.73之间波动,且近年来有增长趋势,年内季节性NDVI动态分析表明高时间分辨率的MODIS数据能够用来区分常绿植被与落叶植被的物候特征,以分析不同植被类型对流域氮、磷流失的风险差异;3)从变化趋势上看,2001-2013年植被覆盖状况改善的区域远大于退化的区域,其中改善区域约占流域面积的55.90%,呈现出一定退化状态的区域约占29.60%(严重退化区域仅占3.97%),而相对稳定不变区域约占14.51%.经与气温与降水等气候因子进行相关性分析表明,植被NDVI与气温呈显著正相关,而降水则不敏感,说明气温是研究区植被生长的主导气候因子.同时发现,人类活动对局部植被变化影响较大.研究结果可为流域水资源与生态环境保护提供空间数据支撑. 相似文献
2.
本文采用中国地区基于卫星观测的植被光合有效辐射资料(FPAR)和月平均气候数据(1982-2000年)来分析中国区域陆面植被与气温、降水的反馈作用.通过计算和分析超前滞后相关系数和反馈系数发现:春、夏季FPAR超前气温一个月相关系数在全国大部分地区为负值,反映出植被生长旺盛,可以降低局地气温.春、秋两季气温与FPAR的同期相关系数较大.夏季降水超前FPAR一个月的正相关性反映出夏季降水对于植被生长存在促进作用.在中国长江流域以南区域,植被对于气温的反馈系数为一致正值,可达0.5 ℃(0.1FPAR)-1;在30°N以北区域显示出一致的负反馈,可达-0.42 ℃(0.1FPAR)-1.FPAR对降水全年反馈系数全国区域平均可达-2.12 cm month-1(0.1FPAR)-1.不同植被类型、不同季节的植被反馈效应也存在差异.植被反馈系数可以用来验证动态植被模式计算的植被大气反馈作用. 相似文献
3.
干旱是影响社会发展和农业生产的重要因素之一。本文基于EOS/MODIS卫星遥感资料,选取江西省2001-2006年的NDVI时间序列数据,分析了NDVI对干旱的响应规律。计算了NDVI与气温、降水之间的关系。并提取植被状态指数(VCI),分析VCI与气温距平、降水距平的空间分布规律。结果表明:2003年江西夏季旱灾以高温少雨天气为主。这一时期的NDVI数值明显低于其他年份同一时期的NDVI值。气温温度越高,NDVI值越大;日照时数时间越长,NDVI值越大;降水量越高,NDVI值越大;降水距平百分率越高,VCI值越高;平均温度距平越小,VCI值越高。说明气候因素对NDVI指数和VCI指数有很大影响。研究表明,基于MODIS的植被指数可以反映旱灾的时空分布规律。 相似文献
4.
利用NOAA/AVHRR归一化植被指数（NDVI）及观测气温与再分析地表气温的差值（Observation Minus Reanalysis, OMR）分析了植被覆盖状况对中国地表气温变化的影响.结果表明,地表气温OMR趋势值与NDVI在空间上呈现出显著的负相关关系,植被覆盖状况差（NDVI小于0.1）的区域地表升温较为显著,气温OMR趋势值超过0.2℃/10a,而植被覆盖度高（NDVI大于0.5）的区域气温OMR趋势值则变化不大,甚至出现降温.气温OMR趋势值对植被的季节变化还有着敏感的响应.不同区域植被覆盖状况的差异可能导致中国地表气温变化对全球变暖的响应不同,预测中国未来气候变化需要考虑植被覆盖状况及其动态变化的影响. 相似文献
5.
气候变化和人类活动对黄土高原植被覆盖变化的影响 总被引：24，自引：0，他引：24
利用GIMMS和SPOT VGT两种归一化植被指数(NDVI)数据对黄土高原地区1981~2006年期间植被覆盖的时空变化进行了研究, 并从气候变化和人类活动的角度分析了植被覆盖变化的原因. 黄土高原地区植被覆盖经历了以下4个阶段: ① 1981~1989年植被覆盖持续增加时期; ② 1990~1998年以小幅波动为特征的相对稳定时期; ③ 1999~2001年植被覆盖迅速下降时期; ④ 2002~2006年植被覆盖进入迅速上升时期. 黄土高原地区植被覆盖变化存在显著的空间差异, 内蒙古和宁夏沿黄农业灌溉区和鄂尔多斯退耕还林还草生态恢复区的植被覆盖明显提高, 而黄土丘陵沟壑区和六盘山、秦岭北坡等山地森林区的植被覆盖明显退化. 从不同的植被类型来看, 沙地、草地和耕地的NDVI上升趋势显著, 而森林植被的NDVI呈明显的下降趋势. 研究表明: 植被覆盖变化是气候变化和人类活动共同作用的结果. 黄土高原地区气候变暖在加剧土壤干燥化抑制夏季植被生长的同时, 提高了春、秋季节植被生长活性, 延长了植被生长期. 黄土高原地区植被覆盖和降水关系密切, 降水变化是植被覆盖变化的重要原因. 农业生产水平的提高致使农业区NDVI在不断上升, 同时, 正在黄土高原大规模进行的退耕还林还草工程建设, 其生态效应也正在呈现. 相似文献
6.
气候变化对中国内陆干旱区山区融雪径流的影响 总被引：29，自引：0，他引：29
气候变化对中纬度山区积雪具有极强的影响, 同时雪盖时空变化和融雪径流的波动被认为是气候变化的指示器. 本研究选择祁连山黑河流域作为中国西北地区山区积雪流域的典型区域, 分析了自1956~2001年近40余年以来气温、降水、累计降雪变化的状况和特点以及春季融雪径流的波动趋势. 结果表明: 黑河上游山区积雪流域的气候变化主要表现在年平均气温的缓慢上升而年降水基本平稳, 累积降雪量也处于波动变化之中. 年内气温的上升幅度以1~2月份比较强烈而其他月份气温上升幅度较小. 利用基于度-日因子算法的融雪径流模型SRM(Snowmelt Runoff Model)模拟气温上升框架下的融雪径流变化情势结果表明山区积雪流域融雪期在时间上的前移, 同时春季融雪径流量呈显著增加趋势且受径流周期变化控制. 相似文献
7.
祁连山浅山区草地生态系统点尺度土壤水分动态随机模拟 总被引：3，自引：0，他引：3
土壤水分动态随机模拟研究是定量理解植被对水分胁迫响应、土壤养分循环的水文控制、植物水分竞争等生态系统动态的关键, 已成为生态水文学的研究热点. 利用2002~2005年生长季土壤湿度连续监测数据及1994~2006年日降水资料, 结合Laio土壤水分动态随机模型与蒙特卡罗(Monte-Carlo)方法, 研究了祁连山浅山区草地生态系统点尺度生长季土壤水分动态与土壤湿度概率密度函数特征. 结果表明: 生长季土壤水分年际变化差异显著, 但无论是丰水年还是枯水年, 表层0~20 cm土壤湿度变异系数均基本保持在0.23左右, 土壤湿度变异系数最大值并不一定发生在表层. 2002~2006年生长季植物根际层土壤湿度概率分布呈单峰状, 峰值出现在s=0.28处, 统计结果与Laio土壤水分动态随机模型模拟结果一致. 将长序列降水信息输入模型, 使用蒙特卡罗方法分析求解得到降水随机波动因素影响下的土壤湿度概率密度函数, 并与不考虑随机波动因素条件下的对比发现: 年际降水随机波动并没有导致土壤湿度概率密度函数出现双峰现象, 但峰的位置却发生了显著偏移, 峰的阔度明显减小, 相应的峰值明显增加. 相似文献
8.
开都河流域融雪径流模拟研究 总被引：1，自引：0，他引：1
高山融雪是塔里木河源流区重要的产流方式,4个山区流域具有面积大、测站稀少、降雨与融雪混合补给径流和显著局部降雨等特征.以开都河流域为研究区,分析流域特征对SRM融雪径流模型参变量的影响,确定相应选取策略以提高融雪径流模拟预报精度,为相似流域融雪径流模拟提供参考.研究结果表明(i)气温输入控制模拟径流的整体趋势,对模拟精度起决定性作用.但测站日均气温数据通常不能代表流域同高程的平均水平,直接作为输入会导致很大误差.基于遥感积雪图和模拟结果分析,开都河流域选择0.5倍巴音布鲁克站日最大气温作为流域平均气温较为合理.(ii)由于雨量站稀少和局部降雨特征显著,计算各高程分带平均降水并不现实.将测站降雨乘以放大系数,并借助参数"降雨径流系数"进行校正,可以满足模型对降雨输入的需求.(iii)根据融雪和降雨位置变化,调整参数"滞时"取值对提高局部洪峰过程的模拟精度非常重要.(iv)随气温升高,降雨增多,未能被有限测站完全监测,导致模拟精度逐步降低. 相似文献
9.
高山融雪是塔里木河源流区重要的产流方式,4个山区流域具有面积大、测站稀少、降雨与融雪混合补给径流和显著局部降雨等特征.以开都河流域为研究区,分析流域特征对SRM融雪径流模型参变量的影响,确定相应选取策略以提高融雪径流模拟预报精度,为相似流域融雪径流模拟提供参考.研究结果表明:(i)气温输入控制模拟径流的整体趋势,对模拟精度起决定性作用.但测站日均气温数据通常不能代表流域同高程的平均水平,直接作为输入会导致很大误差.基于遥感积雪图和模拟结果分析,开都河流域选择0.5倍巴音布鲁克站日最大气温作为流域平均气温较为合理.(ii)由于雨量站稀少和局部降雨特征显著,计算各高程分带平均降水并不现实.将测站降雨乘以放大系数,并借助参数"降雨径流系数"进行校正,可以满足模型对降雨输入的需求.(iii)根据融雪和降雨位置变化,调整参数"滞时"取值对提高局部洪峰过程的模拟精度非常重要.(iv)随气温升高,降雨增多,未能被有限测站完全监测,导致模拟精度逐步降低. 相似文献
10.
青藏高原植被变化与地表热源及中国降水关系的初步分析 总被引：4，自引：0，他引：4
利用设在青藏高原的5个自动气象站（AWS）近地层梯度观测资料、归一化植被指数（GIMMS NDVI）和中国624个台站月降水资料，初步分析了青藏高原植被变化与地表热源及中国降水的关系．结果表明：青藏高原植被与地表热源之间存在明显的正相关关系．高原西部感热与NDVI的正相关关系较高原东部显著，而高原东部地表潜热与NDVI的正相关关系则好于高原西部．植被改善后，各季节地表热源以增加为主，尤其夏季，热源增量最大；冬、春季感热对地表热源增量贡献较大，潜热贡献相对较小；夏、秋季感热与潜热对地表热源增量贡献同等重要．青藏高原植被与中国夏季降水相关系数从南到北，呈“＋-＋”带状分布．植被变化引起的高原地表加热异常可能是影响中国夏季降水的重要因子之一． 相似文献
11.
利用Landsat系列卫星的MSS、TM和ETM+遥感数据,计算了研究区的归一化植被指数(NDVI),并以此为湿地植被活动的指标,研究1973 2011年间该湿地植被变化特征及年内季节变化特征,揭示植被活动在年内和年际变化的控制因子以及湿地植被对于气候变化、人类活动和极端干旱事件的响应特征.结果表明:(1)近40年来南四湖湿地植被各个季节的变化特征不尽相同.春季NDVI呈现先降低后增加的特征,主要先后受到研究区围垦、渔业养殖等人为活动和气候变化(增温)的影响;夏季和冬季的NDVI呈现显著降低趋势,主要受到围垦、渔业养殖等人类活动的影响;秋季NDVI的变化不显著.(2)年内季节变化方面,湿地植被面积和NDVI都呈现单峰的变化特征,从春季开始增加,在夏季末(全年的第202和205 d)达到最大值,然后开始下降,到冬季降至最低.植被的年内季节变化特征主要受到月均温度的控制.(3)干旱在一定程度上不是湖泊湿地NDVI增加的限制因子.干旱导致湖泊水位下降,滨湖滩地及湖底露出,可能会促进湿地植被生长和植被面积的扩大,使得湿地NDVI增加. 相似文献
12.
1973-2013年红碱淖水域水质变化及驱动力分析 总被引：3，自引：1，他引：2
对1973-2013年8期Landsat MSS、TM、ETM+、OLI影像进行了辐射定标、大气校正、辐射归一化和波段运算等处理;利用归一化差值植被指数（NDVI）,分期提取了红碱淖水域面积,分析了湖水水质及红碱淖周围植被变化.研究表明：40 a间红碱淖水域面积呈阶段性萎缩趋势,1990s后萎缩速率加剧,水域面积总体缩小45.7%;湖区周边NDVI波动性增加显示了水退草进的变化趋势;湖面NDVI值的骤增,暗示叶绿素a或悬浮物浓度增加,间接表明湖区水质变差.根据40 a来水域面积变化,红碱淖的演变进程可依据湖泊面积动态度划分为稳定期（1973-1994年）和萎缩期（1994-2013年）两个阶段,气候暖干化是影响稳定期（1973-1994年）湖泊变化的主要因素,在萎缩期（1994-2013年）气候暖干化叠加人类活动是湖泊水量减少和水质变差的诱因,高强度的人为干扰如人工筑坝、灌溉耗水和煤炭开采是红碱淖水域面积锐减的主要原因. 相似文献
13.
The identification of vegetation community growth season is critical for measuring the response of ecosystems to climate change. In this study, vegetation community growth season is measured via fixed‐point monitoring of dynamic short‐time processes of rock‐fissure seepage in the Taihang Mountain Region (TMR). The hydrometeorological data used in the study are obtained from tipping‐bucket flowmeters and automated weather stations in the region. Significant differences are noted in daily rock‐fissure seepage for different growth seasons. The study shows that during growth seasons, seepage processes in the TMR study area vary with air temperature. Although seepage in the region gradually decreases from 06:20 to 17:00 h, it increases from 18:00 to 06:00 h. Analysis shows a significant (R2 > 0.8) negative correlation between seepage and air temperature during growth seasons. For nongrowth seasons, however, seepage processes exhibit near‐harmonic variations with air temperature. Also, although seepage during nongrowth seasons gradually increases from 02:30 to 12:30 h, it gradually decreases from 13:30 to 02:20 h. A significant (R2 > 0.8) positive correlation also exists between seepage and air temperature during nongrowth seasons. During seasonal crop rotations, however, significant disorders and inconsistencies occur in the seepage processes in the study area. The observed seasonal variations in daily rock‐fissure seepages could lay the scientific basis for the adapting trends in crop growth seasons to climate change. Information on this process is critical for crop production and food security for the millions of people in China and beyond. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
14.
The dynamic of vegetation coverage and its response to climate factors in Inner Mongolia, China 总被引：3，自引：2，他引：1
Yang Yang Jianhua Xu Yulian Hong Guanghui Lv 《Stochastic Environmental Research and Risk Assessment (SERRA)》2012,26(3):357-373
Normalized Difference Vegetation Index (NDVI) is widely recognized as a good indicator of vegetation productivity. Diagnosing
the NDVI trend and understanding climatic factors influences on NDVI can predict the productivity changes under different
climatic scenarios. This paper examined NDVI dynamic and its response to climate factors during a 10 year period (1998–2008)
in Inner Mongolia. The main findings are as follows: (1) The NDVI multi-scale characters can be revealed well by wavelet transform,
and the average NDVI and the NDVI amplitude show a gradually decreased trend from northeast to southwest in Inner Mongolia
during the past 10 years, furthermore, this trend is consistent with the heat and water distribution caused by latitude difference
in north–south direction and Asia monsoon effect in east–west direction. (2) The relation between NDVI and temperature is
the most close, followed by precipitation, sunshine hours and relative humidity. Different vegetation cover types show different
strengths in correlation between NDVI and climate variables with the correlation values decreasing from forest, meadow steppe
to desert steppe in whole. (3) The precipitation and temperature have the same change cycle, both nearly 290 days in the 20
selected stations. The NDVI has the same change cycle with the precipitation and temperature or either 10 days earlier or
later than precipitation and temperature, which supports the significant correlation between NDVI and its climatic factors
from a new perspective. The nearly 290 days change cycle implies that the vegetation growth cycle is nearly 10 months and
there are no obvious differences change cycles in different vegetations. (4) Vegetation dynamic is significantly correlated
to the temperature and precipitation at the time scale of 10, 20, 40, 80, 160, and 320-day, respectively, and the S3 scale
(i.e., the time scale of 80-day), nearly 3 months (one season), is most significant and suitable for evaluating the vegetation
dynamic to climatic factors. 相似文献
15.
Spatiotemporal variations of vegetation cover on the Chinese Loess Plateau(1981―2006):Impacts of climate changes and human activities 总被引：1，自引：0，他引：1
Spatiotemporal variations of Chinese Loess Plateau vegetation cover during 1981-2006 have been investigated using GIMMS and SPOT VGT NDVI data and the cause of vegetation cover changes has been analyzed, considering the climate changes and human activities. Vegetation cover changes on the Loess Plateau have experienced four stages as follows: (1) vegetation cover showed a continued increasing phase during 1981―1989; (2) vegetation cover changes came into a relative steady phase with small fluctuations during 1990―1998; (3) vegetation cover declined rapidly during 1999―2001; and (4) vegetation cover increased rapidly during 2002―2006. The vegetation cover changes of the Loess Plateau show a notable spatial difference. The vegetation cover has obviously increased in the Inner Mongolia and Ningxia plain along the Yellow River and the ecological rehabilitated region of Ordos Plateau, however the vegetation cover evidently decreased in the hilly and gully areas of Loess Plateau, Liupan Mountains region and the northern hillside of Qinling Mountains. The response of NDVI to climate changes varied with different vegetation types. NDVI of sandy land vegetation, grassland and cultivated land show a significant increasing trend, but forest shows a decreasing trend. The results obtained in this study show that the spatiotemporal variations of vegetation cover are the outcome of climate changes and human activities. Temperature is a control factor of the seasonal change of vegetation growth. The increased temperature makes soil drier and unfavors vegetation growth in summer, but it favors vegetation growth in spring and autumn because of a longer growing period. There is a significant correlation between vegetation cover and precipitation and thus, the change in precipitation is an important factor for vegetation variation. The improved agricultural production has resulted in an increase of NDVI in the farmland, and the implementation of large-scale vegetation construction has led to some beneficial effect in ecology. 相似文献
16.
The Budyko framework is an efficient tool for investigating catchment water balance, focusing on the effects of seasonal changes in climate (S) and vegetation cover (M) on catchment evapotranspiration (ET). However, the effects of vegetation seasonality on ET remain largely unknown. The present study explored these effects by modelling interannual variations in ET considering vegetation and climate seasonality using the Budyko framework. Reconstructed 15-day GIMMS NDVI3g timeseries data from 1982 to 2015 were used to estimate M and extract the relative duration of the vegetation growing season (GL) in the Yellow River Basin (YRB). To characterize S, seasonal variations in precipitation and potential ET were extracted using a Gaussian algorithm. Analysis of the observed datasets for 19 catchments revealed that interannual variation in the catchment parameter ϖ (in Fuh's equation) was significantly and positively correlated with M and GL. Conversely, ϖ was significantly but negatively correlated with S. Furthermore, stepwise linear regression was used to calibrate the empirical formula of ϖ for these three dimensionless parameters. Following validation, based on observations in the remaining 11 catchments, ϖ was integrated into Fuh's equation to accurately estimate annual ET. Over 79% subcatchments showed an upward trend (0.9 mm yr−1), whereas fewer than 21% subcatchments showed a downward trend (−0.5 mm yr−1) across YRB. In the central region of the middle reach, ET increased with increased M, prolonged GL, and decreased S, whereas in the source region of YRB, ET decreased with decreased M and shortened GL. Our study provides an alternative method to estimate interannual ET in ungauged catchments and offers a novel perspective to investigate hydrological responses to vegetation and climate seasonality in the long-term. 相似文献
17.
三峡工程调节作用对洞庭湖水面面积(2000-2010年)的影响 总被引：3，自引：3，他引：0
以洞庭湖为研究对象,以11年(2000-2010年)Terra/MODIS 16 d最大值合成的植被指数数据产品集MOD13Q1和同期城陵矶水文监测站的水位数据为主要数据源,通过对NDVI和NIR分别设定阈值的方法,实现了洞庭湖水面面积的综合提取,分析了三峡工程建设背景下,洞庭湖水面面积的年际变化特征和年内变化规律,再结合城陵矶水位数据,对水位与水面面积之间的定量关系进行了深入分析.研究结果表明:三峡工程的运行,很大程度上控制着洞庭湖的入湖水量,对洞庭湖防汛工作有利;在气候变化、三峡水库的共同影响下,洞庭湖区水面面积整体上呈减少趋势;水面面积与水位的拟合结果显示两者具有良好的相关性,其中2000-2003年两者的确定性系数达到0.975. 相似文献
18.
Spatiotemporal differentiation of changes in wheat phenology in China under climate change from 1981 to 2010 总被引：3，自引：0，他引：3
Phenology is a reliable biological indicator for reflecting climate change. An examination of changes in crop phenology and the mechanisms driving them is critical for guiding regional agricultural activities in attempts to adapt to climate change. Due to a lack of records based on continuous long-term observation, studies on changes in multiple consecutive phenological stages throughout a whole growing season on a national scale are rarely found, especially with regard to the spatiotemporal differentiation of phenological changes. Using a long-term dataset (1981-2010) of wheat phenology collected from 48 agro-meteorological stations in China, we qualified the spatiotemporal changes of 10 phenological stages as well as the length of wheat growth phases. Results showed that climate and wheat phenology changed significantly during the growing seasons from 1981 to 2010. On average, on a national scale, dates of sowing (0.19 d a-1), emergence (0.06 d a-1), trefoil (0.05 d a-1), and milk ripe (0.06 d a-1) showed a delaying trend, whereas dates of tillering (-0.02 d a-1), jointing (-0.15 d a-1), booting (-0.21 d a-1), heading (-0.17 d a-1), anthesis (-0.19 d a-1), and maturity (-0.10 d a-1) showed an advancing trend. Furthermore, the vegetative growth phase and growing season were shortened by 0.23 and 0.29 d a-1, respectively, whereas the reproductive growth phase was lengthened by 0.06 d a-1. Trends in dates of phenological stages or length of growing phases varied across wheat-planting regions. Moreover, spatiotemporal differentiation of sensitivity in growing season length (GSL) to variations in climatic factors during the growing season between spring and winter wheat were remarkable. The GSL of spring (winter) wheat decreased (increased) with an increase in average temperature during the growing season. In all wheat-planting regions, the GSL increased with the increasing of total precipitation and sunshine duration during the growing season. In particular, the sensitivity of GSL to precipitation for spring wheat was weaker than for winter wheat, while the sensitivity of GSL to sunshine duration for spring wheat was stronger than for winter wheat. Recognition of the spatiotemporal differentiation of phenological changes and their response to various climatic factors will provide scientific support for decision-making in agricultural production. 相似文献
19.
Spatiotemporal variations of Chinese Loess Plateau vegetation cover during 1981–2006 have been investigated using GIMMS and
SPOT VGT NDVI data and the cause of vegetation cover changes has been analyzed, considering the climate changes and human
activities. Vegetation cover changes on the Loess Plateau have experienced four stages as follows: (1) vegetation cover showed
a continued increasing phase during 1981–1989; (2) vegetation cover changes came into a relative steady phase with small fluctuations
during 1990–1998; (3) vegetation cover declined rapidly during 1999–2001; and (4) vegetation cover increased rapidly during
2002–2006. The vegetation cover changes of the Loess Plateau show a notable spatial difference. The vegetation cover has obviously
increased in the Inner Mongolia and Ningxia plain along the Yellow River and the ecological rehabilitated region of Ordos
Plateau, however the vegetation cover evidently decreased in the hilly and gully areas of Loess Plateau, Liupan Mountains
region and the northern hillside of Qinling Mountains. The response of NDVI to climate changes varied with different vegetation
types. NDVI of sandy land vegetation, grassland and cultivated land show a significant increasing trend, but forest shows
a decreasing trend. The results obtained in this study show that the spatiotemporal variations of vegetation cover are the
outcome of climate changes and human activities. Temperature is a control factor of the seasonal change of vegetation growth.
The increased temperature makes soil drier and unfavors vegetation growth in summer, but it favors vegetation growth in spring
and autumn because of a longer growing period. There is a significant correlation between vegetation cover and precipitation
and thus, the change in precipitation is an important factor for vegetation variation. The improved agricultural production
has resulted in an increase of NDVI in the farmland, and the implementation of large-scale vegetation construction has led
to some beneficial effect in ecology.
Supported by the National Natural Science Foundation of China (Grant No. 40671019) and the Knowledge Innovation Project of
the Institute of Geographical Sciences and Natural Resources Research of Chinese Academy of Sciences 相似文献
20.
The weakening relationship between inter-annual temperature variability and vegetation activity in the Northern Hemisphere over the last three decades has been reported by a recent study. However, how and to what extent vegetation activity responds to climate change in China is still unclear. We applied the Pearson correlation and partial correlation methods with a moving 15-y window to the GIMMS NDVI dataset from NOAA/AVHRR and observed climate data to examine the variation in the relationships between vegetation activity and climate variables. Results showed that there was an expanding negative response of vegetation growth to climate warming and a positive role of precipitation. The change patterns between NDVI and climate variables over vegetation types during the past three decades pointed an expending negative correlation between NDVI and temperature and a positive role of precipitation over most of the vegetation types (meadow, grassland, shrub, desert, cropland, and forest). Specifically, correlation between NDVI and temperature (PNDVI-T) have shifted from positive to negative in most of the station of temperature-limited areas with evergreen broadleaf forests, whereas precipitation-limited temperate grassland and desert were characterized by a positive PNDVI-P. This study contributes to ongoing investigations of the effects of climate change on vegetation activity. It is also of great importance for designing forest management strategies to cope with climate change. 相似文献