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Early recovery process and restoration planning of burned pine forests in central eastern Korea 预览
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作者 Ji Hong An Chi Hong Lim +1 位作者 Yong Chan Cho Chang Seok Lee 《林业研究:英文版》 CAS CSCD 2019年第1期243-255,共13页
In central eastern Korea,there has been a continued effort to sustain pine forests because of their value for wood and mushroom production,as well as for other resources.Through the analysis of previously burned areas... In central eastern Korea,there has been a continued effort to sustain pine forests because of their value for wood and mushroom production,as well as for other resources.Through the analysis of previously burned areas,we clarified the effects of fire on vegetation dynamics of pine forests by measuring changes in species composition,population structure,and the growth rates of major tree species.Vegetation analysis was conducted on a series of 100 m^2 plots established in Korean red pine(Pinus densiflora Siebold.&Zucc.)and Mongolian oak(Quercus mongolica Fisch.Ex Ledeb.)forests situated in three different topographic positions on slopes where fire severity varied.We confirmed that most pine trees will succumb to even a surface fire,whereas oak may be killed following high intensity or infrequent fires but will sprout and become dominant.Complete protection from fire favors other,more shade-tolerant deciduous hardwoods.Different restoration plans apply,based on observed vegetation responses for each topographic zone.Near the ridge top,where pine seed sources are most limited,it may be necessary to restore pine forests by planting and to control competing shrubs and herbs.At the mountain foot,where exotic species and species modified by hybridization have invaded aggressively,restoration that involves the introduction of natural vegetation is required.Mid-slope sites,where pine has been replaced by natural vegetation dominated by Mongolian oak,do not require any form of restorative treatment. 展开更多
关键词 VEGETATION SUCCESSION VEGETATION type FIRE SEVERITY FIRE DISTURBANCE Landscape structure
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Hyper-spectral characteristics of rolled-leaf desert vegetation in the Hexi Corridor,China
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作者 WEI Huaidong YANG Xuemei +4 位作者 ZHANG Bo DING Feng ZHANG Weixing LIU Shizeng CHEN Fang 《干旱区科学:英文版》 SCIE CSCD 2019年第3期332-344,共13页
Desert plants survive harsh environment using a variety of drought-resistant structural modifications and physio-ecological systems.Rolled-leaf plants roll up their leaves during periods of drought,making it difficult... Desert plants survive harsh environment using a variety of drought-resistant structural modifications and physio-ecological systems.Rolled-leaf plants roll up their leaves during periods of drought,making it difficult to distinguish between the external structures of various types of plants,it is therefore necessary to carry out spectral characteristics analysis for species identification of these rolled-leaf plants.Based on hyper-spectral data measured in the field,we analyzed the spectral characteristics of seven types of typical temperate zone rolled-leaf desert plants in the Hexi Corridor,China using a variety of mathematical transformation methods.The results show that:(1)during the vigorous growth period in July and August,the locations of the red valleys,green peaks,and three-edge parameters,namely,the red edge,the blue edge,and the yellow edge of well-developed rolled-leaf desert plants are essentially consistent with those of the majority of terrestrial vegetation types;(2)the absorption regions of liquid water,i.e.,1400-1500 and 1600-1700 nm,are the optimal bands for distinguishing various types of rolled-leaf desert plants;(3)in the leaf reflectance regions of 700-1250 nm,which is controlled by cellular structure,it is difficult to select the characteristic bands for differentiation rolled-leaf desert vegetation;and(4)after processing the spectral reflectance curves using a first-order differential,the envelope removal method,and the normalized differential ratio,we identify the other characteristic bands and parameters that can be used for identifying various types of temperate zone rolled-leaf desert plants,i.e.,the 510-560,650-700 and 1330-1380 nm regions,and the red edge amplitude.In general,the mathematical transformation methods in the study are effective tools to capture useful spectral information for species identification of rolled-leaf plants in the Hexi Corridor. 展开更多
关键词 rolled-leaf desert VEGETATION spectral CHARACTERISTICS mathematical transformation VEGETATION identification Hexi CORRIDOR
2002-2016年华北平原植被生长状况及水文要素时空特征分析 预览
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作者 曹艳萍 秦奋 +2 位作者 庞营军 赵芳 黄金亭 《生态学报》 CAS CSCD 北大核心 2019年第5期1560-1571,共12页
基于MODIS增强型植被指数(EVI)资料,结合降水、GRACE重力卫星水储量(TWS)、地下水、土壤水等资料,分析华北平原植被2002-2016年间的生长状况及各水文要素时空分布特征。研究结果表明:(1)2002-2016年间华北平原植被呈好转趋势,降水、水... 基于MODIS增强型植被指数(EVI)资料,结合降水、GRACE重力卫星水储量(TWS)、地下水、土壤水等资料,分析华北平原植被2002-2016年间的生长状况及各水文要素时空分布特征。研究结果表明:(1)2002-2016年间华北平原植被呈好转趋势,降水、水储量、土壤水、地下水等水文要素值呈减少趋势。(2)黄淮平原区植被以农作物为主,植被覆盖度呈增加趋势,而降水、水储量、地下水、土壤水均呈减少趋势,超采地下水灌溉农作物是短期内保障粮食安全的重要措施。(3)燕山-太行山山麓平原区、冀鲁豫低洼平原区的城乡居民用地区域植被覆盖显著减少,而降水增多,水储量、土壤水、地下水减少,人类活动对植被和水文要素贡献量大。(4)山东丘陵农林区分布着林地和草地,这些区域生长季的植被指数呈减少趋势,与降水量减少呈正相关关系。在气候变化和人类活动影响的大背景下,探讨不同生态环境的植被生长特征,清楚植被对水文变化的响应机理,可以消除影响植被生长的不利因素,为制定合理用水制度提供理论依据。 展开更多
关键词 植被 增强型植被指数 降水 水储量 地下水 土壤水
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Submerged flexible vegetation impact on open channel flow velocity distribution: An analytical modelling study on drag and friction 预览
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作者 Jaan H. Pu Awesar Hussain +3 位作者 Ya-kun Guo Nikolaos Vardakastanis Prashanth R. Hanmaiahgari Dennis Lam 《水科学与水工程:英文版》 EI CAS CSCD 2019年第2期121-128,共8页
In this paper,an analytical model that represents the streamwise velocity distribution for open channel flow with submerged flexible vegetation is studied.In the present vegetated flow modelling,the whole flow field h... In this paper,an analytical model that represents the streamwise velocity distribution for open channel flow with submerged flexible vegetation is studied.In the present vegetated flow modelling,the whole flow field has been separated into two layers vertically: a vegetated layer and a non-vegetated free-water layer.Within the vegetated layer,an analysis of the mechanisms affecting water flow through flexible vegetation has been conducted.In the non-vegetated layer,a modified log-law equation that represents the velocity profile varying with vegetation height has been investigated.Based on the studied analytical model,a sensitivity analysis has been conducted to assess the influences of the drag (CD) and friction (Cf ) coefficients on the flow velocity.The investigated ranges of CD and Cf have also been compared to published values.The findings suggest that the CD and Cf values are non-constant at different depths and vegetation densities,unlike the constant values commonly suggested in literature.This phenomenon is particularly clear for flows with flexible vegetation,which is characterised by large deflection. 展开更多
关键词 ANALYTICAL model FLEXIBLE VEGETATION Flow VELOCITY FRICTION Drag SUBMERGED VEGETATION
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生态保护工程和气候变化对长江源区植被变化的影响量化
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作者 唐见 曹慧群 陈进 《地理学报》 EI CSSCI CSCD 北大核心 2019年第1期76-86,共11页
分析长江源区生态保护工程和气候变化对植被变化的影响程度,对于长江源区生态工程的生态效益评估,以及区域植被适应性生态管理政策的制定具有重要意义。因此,本文基于1982-2015年的归一化植被指数数据(Normalized Difference Vegetation... 分析长江源区生态保护工程和气候变化对植被变化的影响程度,对于长江源区生态工程的生态效益评估,以及区域植被适应性生态管理政策的制定具有重要意义。因此,本文基于1982-2015年的归一化植被指数数据(Normalized Difference Vegetation Index,NDVI)和气象数据,分析长江源区植被NDVI的时空变化规律,构建预测植被NDVI对气候因子响应的人工神经网络模型,在此基础上,在年和季节尺度上量化气候变化和生态保护工程对长江源区植被变化的影响程度。结果表明:①在长江源区气候条件变化和生态保护工程影响下,长江源区植被退化得到遏制,植被生长呈好转趋势;②海拔相对较低的通天河附近植被NDVI增加幅度较大,高海拔的沱沱河和当曲流域的植被NDVI增加幅度相对较小;③长江源区植被NDVI对气候因子响应存在1~2月的滞后性。构建的人工神经网络模型的拟合优度参数人工神经网模型具有较高的预测精度,可以用来模拟植被NDVI对气候因子的响应;④年尺度的植被NDVI增加受到生态保护工程的影响程度(58.5%)大于气候变化的影响程度(41.5%)。生长季生态保护工程对NDVI的影响程度(63.3%)大于气候变化对NDVI的影响程度(36.7%),而非生长季气候变化是影响长江源区植被生长的关键要素(52.8%)。研究结果有助于为长江源区植被生态系统恢复、管理和利用战略的科学制定提供决策依据。 展开更多
关键词 植被 气候变化 生态保护工程 归一化植被指数 人工神经网络 长江源区
基于MODIS-EVI的广西西江流域植被时空变化特征及其影响因素 预览
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作者 苏俊磊 罗为群 +4 位作者 王广哲 杨奇勇 周永华 黄静 蒋忠诚 《水土保持研究》 CSCD 北大核心 2019年第3期232-238,共7页
基于MODIS-EVI数据对2007—2016年广西西江流域植被时空变化特征进行了分析,进而探讨其影响因素。结果表明:近10年来,研究区月EVI呈周期性变化,每年7—8月份最高,1—2月份最低,明显受到季节性气候等自然因素控制。EVI年际变化总体呈上... 基于MODIS-EVI数据对2007—2016年广西西江流域植被时空变化特征进行了分析,进而探讨其影响因素。结果表明:近10年来,研究区月EVI呈周期性变化,每年7—8月份最高,1—2月份最低,明显受到季节性气候等自然因素控制。EVI年际变化总体呈上升的趋势,可能与一系列植被保护措施有关,但存在两次骤然下降现象,可能是受到重大自然灾害的影响。岩溶区与非岩溶区EVI变化趋势与全区基本一致。研究区EVI具有明显的空间差异,EVI高值(>0.4)主要分布于高海拔或人为破坏小的地区,适合实施封山育林、人工造林等生态修复举措;EVI低值(≤0.4)主要分布于水系发达或城市中心地带等低海拔地区,受到自然条件和城镇化发展的制约。另外,研究区植被EVI与气温和降雨均呈显著正相关,且与气温的相关性明显高于降雨,对气温和降雨的响应均存在1个月的滞后期。 展开更多
关键词 MODIS-EVI 植被 时空变化 西江流域 广西
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山东河流湿地植被构成及区系研究
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作者 梁玉 范小莉 +3 位作者 马良 王强 房用 王卫东 《山东大学学报:理学版》 CAS CSCD 北大核心 2019年第7期21-25,34共6页
湿地是全球重要的陆地碳库之一,对于全球变化的响应十分敏感。根据有关调查资料,对山东省河流湿地植被构成、河流湿地植物生长型及其植物区系地理成分等进行了分析,阐述了它们与植物之间的关系。山东省河流湿地面积257 795.20 hm^2,占... 湿地是全球重要的陆地碳库之一,对于全球变化的响应十分敏感。根据有关调查资料,对山东省河流湿地植被构成、河流湿地植物生长型及其植物区系地理成分等进行了分析,阐述了它们与植物之间的关系。山东省河流湿地面积257 795.20 hm^2,占全省湿地面积的14.84%。山东省河流湿地内分布植物82科、216属、301种。在植物区系地理成分上,包括15个类型和12个变型。温带性质和热带性质的分布型和变型的属为145个,占总属数的67.13%,体现了植物属分布的温带和热带特点。 展开更多
关键词 河流湿地 植被 区系
Evaluation of the SMOS and SMAP soil moisture products under different vegetation types against two sparse in situ networks over arid mountainous watersheds, Northwest China
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作者 Lanhui ZHANG Chansheng HE +1 位作者 Mingmin ZHANG Yi ZHU 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第4期703-718,共16页
Assessment of the suitability of satellite soil moisture products at large scales is urgently needed for numerous climatic and hydrological researches, particularly in arid mountainous watersheds where soil moisture p... Assessment of the suitability of satellite soil moisture products at large scales is urgently needed for numerous climatic and hydrological researches, particularly in arid mountainous watersheds where soil moisture plays a key role in landatmosphere exchanges. This study presents evaluation of the SMOS(L2) and SMAP(L2_P_E and L2_P) products against ground-based observations from the Upstream of the Heihe River Watershed in situ Soil Moisture Network(UHRWSMN) and the Ecological and Hydrological Wireless Sensor Network(EHWSN) over arid high mountainous watersheds, Northwest China.Results show that all the three products are reliable in catching the temporal trend of the in situ observations at both point and watershed scales in the study area. Due to the uncertainty in brightness temperature and the underestimation of effective temperature, the SMOS L2 product and both the SMAP L2 products show "dry bias" in the high, cold mountainous area. Because of the more accurate brightness temperature observations viewing at a constant angle and more suitable estimations of single scattering albedo and optical depth, both the SMAP L2 products performed significantly better than the SMOS product.Moreover, comparing with station density of in situ network, station representation is much more important in the evaluation of the satellite soil moisture products. Based on our analysis, we propose the following suggestions for improvement of the SMOS and SMAP product suitability in the mountainous areas: further optimization of effective temperature;revision of the retrieval algorithm of the SMOS mission to reduce the topographic impacts;and, careful selection of in situ observation stations for better representation of in situ network in future evaluations. All these improvements would lead to better applicability of the SMOS and SMAP products for soil moisture estimation to the high elevation and topographically complex mountainous areas in arid regions. 展开更多
关键词 SMOS SMAP EVALUATION Different vegetation types SPARSE in situ NETWORKS ARID mountainous watershed
Quantitative indicative significance of pollen assemblages on vegetation coverage in deciduous Quercus forest in the central Loess Plateau, China
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作者 Yuanhao SUN Shengrui ZHANG +5 位作者 Qinghai XU Yiwen LI Wei SHEN Tao WANG Zhongze ZHOU Ruchun ZHANG 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第6期992-1001,共10页
We compared the pollen assemblages of surface moss samples and corresponding vegetation inventory data from 34 sites in the Huangling region of the central Loess Plateau. Our aims were to determine the characteristics... We compared the pollen assemblages of surface moss samples and corresponding vegetation inventory data from 34 sites in the Huangling region of the central Loess Plateau. Our aims were to determine the characteristics of the pollen assemblages from the deciduous broadleaved forest climax community and its significance in terms of vegetation type and species composition. The pollen assemblages are dominated by woody plants such as Quercus(42% of total terrestrial pollen),Betula(16%) and Pinus(12%), with minor differences between different plant communities. The pollen assemblages of individual sampling sites differed from the vegetation composition within the 0–100 m scope and were more similar to the vegetation coverage within the 0–1000 m scope. This indicates that the surface pollen assemblages mainly reflect the comprehensive information from the vegetation composition of a large area, rather than the vegetation composition close to the sampling site. The contents of Quercus, Betula and Pinus pollen are high, and close to their vegetation coverage;whereas the contents of deciduous broadleaved arbor taxa(such as Malus and Acer) are lower, but their corresponding regional vegetation cover is higher. This suggests that the vegetation information conveyed by poorly-represented pollen taxa should be considered when interpreting stratigraphic pollen assemblages. Using the observed quantitative relationships between pollen and vegetation of the main taxa, we reconstructed the regional vegetation composition in the Gonghai Lake area of the northeastern Loess Plateau during the middle Holocene(7300–5000 yr BP). The results indicated that Quercus-dominated deciduous broadleaved forest climax community developed in the mountains surrounding the lake. 展开更多
关键词 Loess Plateau DECIDUOUS broadleaved FOREST CLIMAX community POLLEN assemblage Absolute vegetation coverage
西辽河流域通辽平原区地下水埋深与植被及土壤特征的关系 预览
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作者 朱永华 张生 +3 位作者 孙标 赵胜男 张颖 刘志强 《水土保持通报》 CSCD 北大核心 2019年第1期29-36,共8页
[目的]揭示地下水埋深与植物群落特征及土壤理化特性相关关系,为西辽河流域通辽平原区生态环境健康和谐发展提供依据。[方法]运用时空替代和土壤单重分形等方法,定量分析植被群落和土壤颗粒变化特征,并探讨二者对地下水埋深变化的响应... [目的]揭示地下水埋深与植物群落特征及土壤理化特性相关关系,为西辽河流域通辽平原区生态环境健康和谐发展提供依据。[方法]运用时空替代和土壤单重分形等方法,定量分析植被群落和土壤颗粒变化特征,并探讨二者对地下水埋深变化的响应机理。[结果]不同地下水埋深条件下植被特征与多样性指标值大小顺序为2—3m>1—2m>0—1m>(>4m)>3—4m;研究区表层土壤粒度组成以粉粒为主,其中粉粒含量在52.03%~84.78%之间,土壤颗粒平均粒径从大到小依次为3—4m,>4m,0—1m,1—2m和2—3m,颗粒分形维数分别为2.34~2.49之间;分选级别分别为较差、差、较差、较差和差;偏度等级分别为近于对称、近于对称、近于对称、负偏和负偏;各种样地峰态均属很尖窄。[结论]研究区植被群落的演替表现为随着地下水补给条件的变化呈非地带性草甸植被向地带性典型草原植被的演替过程,地下水埋深2—3m处为植被演替临界范围。 展开更多
关键词 地下水埋深 植被 土壤 通辽平原区
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围封和放牧对彰武地区沙质草地植被影响 预览
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作者 董文宇 《防护林科技》 2019年第1期29-30,共2页
选择彰武地区放牧和围封8年的沙质草地进行研究,分析了围封与放牧对沙质草地植被的影响。结果表明:围封比放牧总植物数提高了61%,同时植物种类也较多。围封区物种Simpson指数、Shannon-Wiener指数、Pielou均匀度指数分别比放牧区提高了5... 选择彰武地区放牧和围封8年的沙质草地进行研究,分析了围封与放牧对沙质草地植被的影响。结果表明:围封比放牧总植物数提高了61%,同时植物种类也较多。围封区物种Simpson指数、Shannon-Wiener指数、Pielou均匀度指数分别比放牧区提高了542%、106%、和37%。说明围封提高了草原的物种多样性,稳定性不断提高。 展开更多
关键词 沙质草地 围封 放牧 植被 土壤
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The structure of turbulent flow through submerged flexible vegetation 预览
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作者 Wen-xin Huai Jiao Zhang +3 位作者 Gabriel G.Katul Yong-guang Cheng Xue Tang Wei-jie Wang 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第2期274-292,共19页
The hydrodynamics of turbulent flow through submerged flexible vegetation is investigated in a flume using acoustic Doppler velocimetery(ADV)measurements.The flow characteristics such as the energetics and momentum tr... The hydrodynamics of turbulent flow through submerged flexible vegetation is investigated in a flume using acoustic Doppler velocimetery(ADV)measurements.The flow characteristics such as the energetics and momentum transfer derived from convcntional spectral and quadrant analyses are considered as the flow encounters a finite vegetation patch.Consistent with numerous canopy flow experiments,a shear layer and coherent vortex structures near the canopy top emerge caused by Kelvin-Helmholtz instabilities after the flow equilibrates with the vegetated layer.These in stabilities are commonly attributed to velocity differences between non-vegetated and vegetated canopy layers in agreement with numerous experiments and simulations conducted on dense rigid canopies.The power-spectral density function for vertical velocity turbulent fluctuations at different downstream positions starting from the edge of the vegetation layer are also computed.For a preset water depth,the dominant dimensionless frequency is found to be surprisingly invariant around 0.027 despite large differences in vegetation densities.The ejection and sweep events significantly contribute to the Reynolds stresses near the top of the vegetation.The momentum flux carried by ejections is larger than its counterpart carried by the sweeps above the canopy top.However,the momentum flux carried by sweeps is larger below the top of the canopy. 展开更多
关键词 Artificial flexible VEGETATION COHERENT VORTEX structures drag force open channel flow VELOCITY distribution
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密云水库库滨带不同植被配置下面源污染特征分析 预览
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作者 李凯 程金花 陈仲旭 《生态环境学报》 CSCD 北大核心 2019年第6期1183-1192,共10页
密云水库是北京市重要地表水源地,在首都经济发展中发挥着重要作用。随着密云水库水位上涨以及库滨带工程建设,其生态环境发生了一系列变化。通过设立12个不同植被配置的野外标准径流小区,研究天然降雨条件下不同植被配置对于总氮(TN)... 密云水库是北京市重要地表水源地,在首都经济发展中发挥着重要作用。随着密云水库水位上涨以及库滨带工程建设,其生态环境发生了一系列变化。通过设立12个不同植被配置的野外标准径流小区,研究天然降雨条件下不同植被配置对于总氮(TN)、总磷(TP)、氨氮(NH4^+-N)、化学需氧量(COD)、生物需氧量(BOD5)5个面源污染指标的影响,以期为库滨带建设提供参考数据。研究结果表明,(1)天然降雨条件下乔灌草混交小区柳树(Salix matsudana)+丁香(Syringa oblata)+蒿(Artemisia annua)的减流作用最好,平均减流作用为62.9%,减沙作用最好的是毛白杨(Populus tomentosa)+紫丁香(Syringa oblata)+葎草(Humulus scandens)小区,减沙作用为78.18%。(2)植被对于面源污染有着显著的控制效果,毛白杨+紫丁香+葎草的乔灌草配置控制效果最好,对TN、TP、NH4^+-N、COD、BOD5的削减率在77.76%-92.24%之间。(3)3次降雨条件下各植被配置小区随着时间的推移、降雨量的减少、降雨强度的减弱,TN的流失模数显著减少(P<0.05);TP流失变化较大,但总体上呈减小的趋势;同一种植被配置下NH4+-N流失模数显著减少(P<0.05);COD和BOD5下降趋势明显。在各小区随时间及降雨条件变化的面源污染控制削减纵向比较中,3次天然降雨条件下,5个面源污染指标呈递减趋势。对于TP的削减控制,油松(Pinus tabuliformis)+臭椿(Ailanthus altissima)小区最优;而其余4个指标,削减比最高的均为油松+金叶榆(Ulmus pumila)小区。由此可见此种植被配置模式对于面源污染控制的长期效益最好。 展开更多
关键词 径流 植被 配置 面源污染
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东莞市不同类型植被降温效果分析 预览
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作者 苏雅丽 杨燕琼 《林业调查规划》 2019年第3期61-66,共6页
以2014年东莞市LandsatTM卫星影像为基础,反演地温,结合实地调查数据、气象监测站数据,分析了东莞市植被构成现状,利用温度变化指标值分析比较同一龄组下不同林分以及同一林分不同郁闭度下的降温效果。结果表明,东莞市地表植被中,其它... 以2014年东莞市LandsatTM卫星影像为基础,反演地温,结合实地调查数据、气象监测站数据,分析了东莞市植被构成现状,利用温度变化指标值分析比较同一龄组下不同林分以及同一林分不同郁闭度下的降温效果。结果表明,东莞市地表植被中,其它绿地类型面积占比最大,占植被覆盖面积的51.60%,其次是荔枝林(13.16%)、阔叶混交林(11.59%)以及桉树林(10.02%)等;与无植被覆盖地区当天地表平均气温相比,在同一龄组下,荷木的降温效果最佳,温度变化指标值为21.16%;在林分水平一致的前提下,林分的郁闭度不同,产生的降温效果也不一样,郁闭度为0.8及以上时,大多数乔木林降温效果最佳。 展开更多
关键词 植被 林分 遥感 地温反演 降温作用 郁闭度 东莞市
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宝鸡市植被叶子重金属分布规律及生态风险评价
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作者 张俊辉 林青 +3 位作者 姜珊 刘滨 李东兴 王彦虎 《环境科学》 EI CAS CSCD 北大核心 2019年第2期978-986,共9页
以宝鸡市滨河路植被叶子为研究对象,对不同种类以及不同高度的植被叶子重金属含量和污染程度进行分析.结果表明,植物叶子中重金属含量随着植被高度呈递减的变化趋势;其中Cr、Mn和Pb含量在植被叶子中富集最多,Cr、Cu、Ni和Mn含量的最高... 以宝鸡市滨河路植被叶子为研究对象,对不同种类以及不同高度的植被叶子重金属含量和污染程度进行分析.结果表明,植物叶子中重金属含量随着植被高度呈递减的变化趋势;其中Cr、Mn和Pb含量在植被叶子中富集最多,Cr、Cu、Ni和Mn含量的最高值均出现在金叶女贞的植被叶子中;Pb富集最多的是大叶女贞,Cd富集最多的是塔松,As富集最多的是红叶李;运用单因子污染指数法和内梅罗综合指数法对植被叶子的污染程度进行评价,Hakanson潜在生态风险评价法评估了滨河路不同类型植被叶子中Cr、Cu、Ni、Mn、Pb、Cd和As等7种重金属的潜在生态危害,滨河路7种植被叶子综合污染指数属重度污染,具有极强的综合危害性;7种重金属的平均潜在生态风险程度大小顺序为:Cd> Ni> Cr> As> Pb> Cu> Mn,RI值变化范围为19. 04~4 020. 29. 展开更多
关键词 宝鸡市 植被 重金属 污染 生态风险评价
基于多普勒频谱的建筑物与植被场景分类技术 预览
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作者 柴晓飞 罗丁利 +1 位作者 徐丹蕾 杨磊 《火控雷达技术》 2019年第1期18-23,共6页
利用低分辨雷达对建筑物和植被进行分类具有重要意义。本文通过对两类目标在有风条件下频谱进行分析,提取具有可分辨力的特征,首先选用支持向量机(Support Vector Machine,SVM)对两类目标进行点迹级鉴别,其次通过投票法对点迹分类结果... 利用低分辨雷达对建筑物和植被进行分类具有重要意义。本文通过对两类目标在有风条件下频谱进行分析,提取具有可分辨力的特征,首先选用支持向量机(Support Vector Machine,SVM)对两类目标进行点迹级鉴别,其次通过投票法对点迹分类结果进一步融合来提高识别率,最后将雷达实测数据的实验结果与该地区高清卫星地图进行对比,验证所提方法的有效性和稳健性,并给出了该研究方法的适用条件。 展开更多
关键词 有风 建筑物 植被 特征提取 支持向量机 投票法
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Changes of vegetation in southern China
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作者 Weiming WANG Chunhai LI +1 位作者 Junwu SHU Wei CHEN 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第8期1316-1328,共13页
In order to reveal the changes of vegetation in southern China since the Last Glacial Maximum, we have established high-resolution time scales and palynological sequences of borehole profiles by drilling cores in some... In order to reveal the changes of vegetation in southern China since the Last Glacial Maximum, we have established high-resolution time scales and palynological sequences of borehole profiles by drilling cores in some weak areas of the research to restore vegetation changes over the past 20,000 years on the basis of previous work. This paper gives the vegetation zoning maps of 18, 9 and 6 ka BP respectively in southern China, and describes the distribution characteristics of plants in different zones/subzones. The results show that the vegetation zonations around 18 ka BP were significantly different from that at present.It appeared in turn with Cold-temperate coniferous forest and alpine meadow steppe zone, and Temperate mixed coniferous and broad-leaved forest zone/warm temperate deciduous broad-leaved forest zone from northwest to southeast in the west, and Temperate mixed coniferous and broad-leaved forest zone, Warm temperate deciduous broad-leaved forest zone, and Northern subtropical mixed evergreen and deciduous broad-leaved forest zone from north to south in the central and east. The vegetation distribution around 9 ka BP changed distinctively. Except that the northwest part was located in Mountain temperate mixed coniferous and broad-leaved forest zone, the vegetation in other areas occurred in turn with North subtropical mixed evergreen and deciduous broad-leaved forest subzone, Mid-subtropical typical evergreen broad-leaved forest subzone, and South subtropical monsoon evergreen broad-leaved forest subzone/Tropical seasonal rainforest and rainforest zone from north to south.There was little change in the appearance of vegetation zonations between 6 and 9 ka BP, but the northern edge of each vegetation belt moved a little northward, reflecting that the overall climate became warmer around 6 ka BP. The vegetation changes in southern China over the past 20,000 years were largely driven by environmental changes. Climate change was the main factor affecting the vegetation distribution. The impact of human 展开更多
关键词 VEGETATION CHANGES 18 KA BP 9 KA BP 6 KA BP Environmental change SOUTHERN China
基于Landsat影像的石漠化区植被动态监测及治理效益研究 预览
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作者 章维鑫 曹建华 吴秀芹 《农业工程学报》 EI CAS CSCD 北大核心 2019年第8期221-229,共9页
生态恢复工程是缓解石漠化、保持土壤、提高植被覆盖率的有效措施之一,是区域经济和生态可持续发展的关键。为了研究近30 a泸西县植被的时空变化特征、驱动因素以及石漠化综合治理生态工程实施的生态效益。本文基于1986-2016 Landsat T... 生态恢复工程是缓解石漠化、保持土壤、提高植被覆盖率的有效措施之一,是区域经济和生态可持续发展的关键。为了研究近30 a泸西县植被的时空变化特征、驱动因素以及石漠化综合治理生态工程实施的生态效益。本文基于1986-2016 Landsat TM数据,借助Mann-Kendall突变分析、Thei-Sei Median趋势分析等方法进行了研究,结果表明:1)30 a间,泸西县植被覆盖整体呈增加趋势,平均增速为0.43%/10 a,2001年是重要的转折点,增速由之前的0.35%/10 a增加到0.63%/10 a;2)在变化趋势上,泸西县植被覆盖呈增加和减少趋势的面积分别占85.21%和14.79%。1986-2000年期间,植被覆盖呈极显著上升的面积为7.71%,零星分布在北部地区;2001-2016年,植被覆盖呈现极显著性上升的面积占21.62%,主要分布在石漠化综合治理工程集中分布的东部山区;3)气温和降水的增加都对植被起到正向作用,气温对植被的影响明显大于降水。2000年之后,人类活动对植被的提升起到了重要的作用,其中对植被覆盖起积极作用的面积占79.6%,起消极作用的占20.4%;在贡献大小上,气候变化对NDVI的影响大小为39.1%,人类活动对NDVI的影响作用为60.9%。植被改善过程中人类活动的作用大于气候变化,石漠化综合治理生态工程是2001-2016年植被增加的重要驱动力之一。 展开更多
关键词 遥感 时空变化 植被 归因分析 泸西县
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2001-2016年毛乌素沙地植被的生长状况 预览
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作者 曹艳萍 庞营军 贾晓红 《水土保持通报》 CSCD 北大核心 2019年第2期29-37,共9页
[目的]对2001—2016年毛乌素沙地植被生长状况进行研究,为该区域生态系统的可持续发展提供理论支持。[方法]基于MODISEVI植被指数分析2001—2016年毛乌素沙地生长季和非生长季的植被生长状况,并讨论植被生长与气候变化、人类活动的关系... [目的]对2001—2016年毛乌素沙地植被生长状况进行研究,为该区域生态系统的可持续发展提供理论支持。[方法]基于MODISEVI植被指数分析2001—2016年毛乌素沙地生长季和非生长季的植被生长状况,并讨论植被生长与气候变化、人类活动的关系。[结果]①毛乌素沙地植被覆盖度偏低,南部植被覆盖度明显高于北部区域。②毛乌素沙地2001—2016年植被覆盖度好转趋势明显。③生长季,毛乌素沙地南部和东部地区植被覆盖度变化速率大于中部和北部地区;且南部和东部的植被覆盖度部分呈显著增加,部分呈显著减小趋势。非生长季,南部地区植被覆盖度以显著增加为主。④毛乌素沙地EVI年最大值与降水呈正相关,与气温呈弱负相关;EVI年最小值与降水呈强正相关,与气温呈弱正相关。⑤农作物种植面积的增加、大规模人工造林以及大牲畜规模的控制等人类活动有助于植被覆盖度的提高。[结论]受气候因素和人类活动影响,21世纪以来毛乌素沙地植被生长状况好转。 展开更多
关键词 毛乌素沙地 植被 气候变化 人类活动
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Comparative Analysis of Fractional Vegetation Cover Estimation Based on Multi-sensor Data in a Semi-arid Sandy Area 预览
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作者 LIU Qiuyu ZHANG Tinglong +3 位作者 LI Yizhe LI Ying BU Chongfeng ZHANG Qingfeng 《中国地理科学:英文版》 SCIE CSCD 2019年第1期166-180,共15页
The estimation of fractional vegetation cover(FVC) is important for identifying and monitoring desertification, especially in arid and semiarid regions. By using regression and pixel dichotomy models, we present the c... The estimation of fractional vegetation cover(FVC) is important for identifying and monitoring desertification, especially in arid and semiarid regions. By using regression and pixel dichotomy models, we present the comparison of Sentinel-2A(S2) multispectral instrument(MSI) and Landsat 8(L8) operational land imager(OLI) data regarding the retrieval of FVC in a semi-arid sandy area(Mu Us Sandland, China, in August 2016). A combination of unmanned aerial vehicle(UAV) high-spatial-resolution images and field plots were used to produce verified data. Based on a normalized difference vegetation index(NDVI) regression model, the results showed that, compared with that of L8, the coefficient of determination(R2) of S2 increased by 26.0%, and the root mean square error(RMSE) and the sum of absolute error(SAE) decreased by 3.0% and 11.4%, respectively. For the ratio vegetation index(RVI) regression model, compared with that of L8, the R2 of S2 increased by 26.0%, and the RMSE and SAE decreased by 8.0% and 20.0%, respectively. When the pixel dichotomy model was used, compared with that of L8, the RMSE of S2 decreased by 21.3%, and the SAE decreased by 26.9%. Overall, S2 performed better than L8 in terms of FVC inversion. Additionally, in this paper, we develop a verified scheme based on UAV data in combination with the object-based classification method. This scheme is feasible and sufficiently robust for building relationships between field data and inversion results from satellite data. Further, the synergy of multi-source sensors(especially UAVs and satellites) is a potential effective way to estimate and evaluate regional ecological environmental parameters(FVC). 展开更多
关键词 fractional vegetation cover (FVC) Sentinel-2A (S2) unmanned AERIAL vehicle (UAV)image PIXEL DICHOTOMY MODEL regression MODEL
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