海岸带盐沼植被指数构建研究

发布时间：2018-05-28 17:22

本文选题：植被指数 + 湿度指数　；参考：《华东师范大学》2017年硕士论文

【摘要】：受人类活动和气候变化影响,我国海岸带盐沼植被面临着严重威胁,其面积、分布以及相应的生态服务功能处于快速变化中。如何快速准确地对海岸带盐沼植被进行精准遥感监测,对维护海岸带盐沼植被资源总量、盐沼生态系统的结构与功能,保持海岸带盐沼湿地资源可持续利用、促进区域社会经济持续健康发展具有重要理论意义与实践指导价值。利用植被指数进行植被遥感提取是陆地生态系统常用的方法。在海岸带特别是潮间带区域,盐沼植被受潮水周期性淹没影响,其下垫面复杂变化。现有常规的多种植被指数不能很好提取潮滩盐沼植被信息,特别是不能有效识别提取潮间带低盖度(30%)的盐沼植被。本项研究以崇明东滩鸟类国家级自然保护区为主要研究区域,考虑潮汐作用对海岸带盐沼植被下垫面的影响,通过野外光谱测量,对研究区典型盐沼植被芦苇(Phragmites australis)、海三棱叇草(Scirpus mariqueter)、互花米草(Spartina alterniflora)在不同盖度以及不同土壤下垫面条件下的盐沼植被反射光谱进行分析,结合植被指数原理,提出一种基于下垫面湿度调节的海岸带盐沼植被指数(Coastal Salt Mashes Vegetation Index,CSMVI)。通过修正湿度和水体影响,有效消除因潮汐过程导致下垫面湿度和水位变化的盐沼植被遥感提取低估的问题。对该指数提取盐沼植被的精度进行了验证,评价了该指数在美国Landsat-8 OLI影像,中国高分一号WFV影像以及法国SPOT-7 NAOMI影像上的适用性。研究结果表明:(1)海岸带盐沼植被的光谱差异主要是植被类型、植被盖度和下垫面共同影响的。典型盐沼植被海三棱叇草、芦苇和互花米草在533～560nm、683～751 nm波长范围内光谱差异显著。在波长350～730nm范围内,海三棱叇草、芦苇、互花米草光谱反射率随盖度增大而减小。到730 nm后的近红外波段,三种植被反射率随盖度增大而增大。在波长350～950nm范围内,植被光谱反射率随潮位升高而增大;在潮位继续升高将植株逐渐淹没后,光谱反射率急剧下降。(2)根据遥感影像光谱和实测野外光谱数据分析表明,湿度及水体对盐沼植被光谱响应差异主要表现在可见光蓝波段、绿波段、红波段和近红外波段。根据该特点,本文提出一种新的植被指数CSMVI,该指数主要是对常规植被指数和湿度指数分析,将抗大气植被指数(ARVI)与归一化水体指数(NDWI)做乘法运算,削弱下垫面湿度及水体带来的影响。通过实地验证得到CSMVI的精度为84.44%,高于归一化植被指数(NDVI)、ARVI和转换型植被指数(TVI)的精度。(3)CSMVI在高分一号WFV(空间分辨率16m)和SPOT-7NAOMI(空间分辨率6m)遥感影像应用结果表明,在长江口和杭州湾区域,CSMVI可适用于不同空间分辨率的遥感影像和不同海岸带区域的盐沼植被提取,采用空间分辨率高的影像所提取的盐沼植被精度更高。(4)本研究仅对下垫面湿度及水体影响进行了调节,对于土壤粒径、土壤盐度、盐沼植被类型等因素并没有考虑在内,在今后的研究中将对下垫面影响因子及盐沼植被分类做进一步研究。另外,对于混合像元问题,将对更高空间分辨率的遥感影像进行应用研究。
[Abstract]:Under the influence of human activities and climate change, the coastal salt marsh vegetation in China is facing a serious threat. Its area, distribution and corresponding ecological service function are in rapid change. How to quickly and accurately monitor the vegetation of coastal salt marsh, to maintain the total amount of vegetation resources in coastal salt marsh and the structure of salt marsh ecosystem It is of great theoretical and practical significance to maintain the sustainable utilization of wetland resources in coastal salt marshes and promote the sustainable and healthy development of regional social and economic development. The use of vegetation index for Remote Sensing Extraction of vegetation is a common method for land ecosystem. In coastal zone, especially in intertidal zone, the vegetation of salt marsh is flooded by tidal water periodicity. The existing conventional multi planting index can not extract the information of the tidal flat salt marsh vegetation, especially the salt marsh vegetation which can not identify the low coverage of the intertidal zone (30%). This study takes the National Nature Reserve of Chongming Dongtan bird as the main research area, considering the tidal effect on the coastal salt marshes. The reflectance spectra of salt marsh vegetation in the typical salt marsh vegetation (Phragmites australis), Scirpus mariqueter, Spartina alterniflora under the conditions of different coverage and soil underlying surface were analyzed by field spectral measurement, and the vegetation index principle was proposed. A coastal zone salt marsh vegetation index (Coastal Salt Mashes Vegetation Index, CSMVI) based on the humidity regulation of the underlying surface. By revising the influence of humidity and water, the problem of Remote Sensing Extraction of salt marsh vegetation caused by the change of the humidity and water level of the underlying surface was effectively eliminated. The accuracy of the extraction of salt marsh vegetation was tested by the index. The applicability of the index to the Landsat-8 OLI image in the United States, the number one WFV image of China and the SPOT-7 NAOMI image in France was evaluated. The results showed that: (1) the spectral differences of the coastal salt marsh vegetation were mainly vegetation types, the vegetation coverage and the underlying surface were influenced by the vegetation cover, the typical salt marsh vegetation, the sea trisex, reed and the rice grass The spectral reflectance in the wavelength range of 533 ~ 560nm and 683~751 nm was significant. In the range of 350 ~ 730nm, the spectral reflectance of the sea trisex, reed, and alterniflora decreased with the increase of coverage. The reflectance of three planting was increased with the increase of coverage in the near infrared band after 730 NM. The spectral reflectance of vegetation in the range of 350 to 950nm followed the wavelength of vegetation. When the tidal level increased, the spectral reflectance decreased sharply after the tidal level continued to inundate the plant. (2) according to the analysis of remote sensing image spectrum and field spectral data, the difference of spectral response between humidity and water body on the salt marsh vegetation was mainly in the visible light blue band, green band, red band and near infrared band. This paper presents a new vegetation index CSMVI, which is mainly the analysis of the conventional vegetation index and the humidity index, and multiplicative operation of the ARVI and the normalized water index (NDWI) to weaken the humidity of the underlying surface and the influence of the water body. The accuracy of the CSMVI is 84.44%, which is higher than the normalized vegetation index through field evidence. The accuracy of the number (NDVI), ARVI and converted vegetation index (TVI). (3) the application of CSMVI at WFV (spatial resolution 16m) and SPOT-7NAOMI (spatial resolution 6m) shows that CSMVI can be used in the remote sensing images of different spatial resolution and the extraction of salt marshes from different coastal zones in the Yangtze Estuary and the Hangzhou Bay area. The precision of salt marsh vegetation extracted by high spatial resolution is higher. (4) this study only regulates the humidity and water influence of the underlying surface, and does not take into account the factors such as soil particle size, soil salinity, and salt marsh vegetation types. In the future research, we will do further research on the influence factors of the underlying surface and the classification of salt marsh vegetation. In addition, for the mixed pixel problem, the application of remote sensing images with higher spatial resolution will be studied.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q948

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