共查询到19条相似文献,搜索用时 78 毫秒
1.
2.
3.
2007和2008年秋季对珠江口滨海湿地进行了2个航次的现状调查,并选择了6条代表性断面进行现场观测和样品采集.结果显示:珠江口滨海湿地的水质污染严重,主要受化学需氧量和生化需氧量的污染,沉积物主要受铜、锌、镉、砷的污染较为严重,特别是铜污染,而且磨刀门断面很有可能存在镉污染源;高等植物主要分布在自然保护区和湿地公园,且以红树林为主;底栖生物多样性不高,均匀度一般.珠江口滨海湿地退化主要表现为天然湿地面积减少、湿地生产力不断下降和湿地环境状况持续恶化等.退化的主要原因是滩涂开发与围填海、污染物大量排放和过度捕捞与养殖等. 相似文献
4.
5.
珠江口淇澳岛红树林湿地变化及调控对策研究 总被引:20,自引:5,他引:20
对珠江口内伶仃洋淇澳岛红树林湿地的变化及其驱动力进行了分析。采用的方法包括收集部分历史资料、三个时相段红树林的遥感图像监测和实地样方调查。根据 2 0 0 4年最新遥感测算 ,大约有 2 0 0hm2 红树林生长在该岛 ,这些红树林是珠江口重要的生态系统 ,但已受到强烈人为干扰。在过去近 2 0年里 ,约 77hm2 的天然红树林被毁掉 ,用于水产养殖、城镇基础设施建设。近些年来研究区红树林面积不断增加 ,尤其是自 1999年实行红树林人工恢复工程以来 ,新引种的红树林 (无瓣海桑Sonneratiaapetala)得以重建。但是淇澳岛红树林斑块的空间格局和种的构成发生了变化 ,红树林群落植物多样性明显减弱。在综合分析基础上 ,根据生态系统管理的思想 ,提出了以构建典型的红树林生态序列和红树林湿地植被多样性为目标的淇澳岛红树林湿地生态系统恢复和建设的建议。 相似文献
6.
根据红树林湿地健康的内涵及红树林湿地特征,分析红树林湿地结构与功能的关系,阐明影响红树林湿地健康的要素,确定健康评价指标选取的原则。在此基础上应用层次分析法(Analytical Hierarchy Process),构建红树林湿地健康评价指标体系。健康评价指标体系由目标层、要素层、要素亚层和指标层4个层组成,其中要素层包括植物群落结构、生物安全性、生境的完整性与稳定性、生境理化性质、生物因子指标5个方面,指标层包括物种组成、物种丰度、建群种比例郁闭度、龄组结构、更新等级等41个指标。 相似文献
7.
珠江口滨海湿地景观格局变化分析 总被引:5,自引:1,他引:5
以专题地图和遥感影像为数据源,采集1986、1995和2005年珠江口滨海湿地数据,选取基于景观类型的景观聚集度指数、景观分维数和基于景观面积的景观多样性指数,从景观类型和景观水平研究珠江口滨海湿地景观格局变化。结果表明:(1)在各湿地景观类型中,面积占绝对优势的是浅海水域景观,面积增加最多的是养殖水面,减少最多的是水田。(2)受人为开发因素影响,湿地总面积持续减少,1986―1995年和1995―2005年湿地总面积相继减少20821hm2和55708hm2,分别相当于研究区总面积的5.3﹪和14.2﹪。(3)湿地景观变化具有显著时间异质性,类型分布具有显著的空间异质性。人为开发和分割湿地景观导致各景观类型聚集度指数不同程度降低,而景观分维数增加,景观多样性指数先小幅增加后大幅下降。(4)湿地景观格局的变化导致湿地整体质心坐标经历了先向北移动0.4km,后向东南迁移6.1km。前后两个时期相比,湿地面积减少速度和质心迁移速度在后期明显加快,由此反映出岸线以上陆域湿地正在加速退化。研究珠江口滨海湿地景观格局变化,可为保护和长期规划珠江口滨海湿地提供科学依据。 相似文献
8.
我国红树林湿地研究进展 总被引:15,自引:3,他引:15
红树林湿地是分布于亚热带、热带滨海地区的典型湿地,具有其它湿地类型所不具备的特殊的演化过程,形成独特的水文、土壤和植被特征。由于人类活动的影响,近年来,我国红树林湿地出现了面积锐减、生态系统结构简化、生物多样性降低、生态功能退化等严重问题,使红树林湿地的可持续利用面临严重挑战。从湿地生态、湿地功能及湿地开发利用、保护与管理等方面评述我国红树林湿地生态系统的研究现状,探讨我国红树林湿地未来研究的主要科学问题,进而明确红树林湿地可持续利用研究的方向和途径。 相似文献
9.
10.
深圳红树林湿地的现状及生态旅游开发对策 总被引:8,自引:1,他引:8
红树林是生长在热带和亚热带沿海潮间带的木本植物群落,有其独特的生态系统。它具有极其重要的生态、社会和经济效益,同时也是一种新兴的生态旅游资源。介绍了深圳红树林湿地的现状、面临的主要威胁,并结合实际情况对开发红树林生态旅游提出了建议。 相似文献
11.
Mangrove forests have important ecological functions in protecting the environment. However, the mangrove wetlands have been largely lost because of intensified human activities in the study area. Remote sensing can be conveniently used for the inventory of mangrove forests because field investigation is very difficult. In this study, a knowledge-based system is developed to retrieve spatio-temporal dynamics of mangrove wetlands using multi-temporal remote sensing data. Radar remote sensing data are also used to provide complementary information for the quantitative analysis of mangrove wetlands. Radar remote sensing is able to penetrate mangrove forests and obtain the trunk information about mangrove structures. The integration of radar remote sensing with optical remote sensing can significantly improve the accuracies of classifying mangrove wetland types and estimating wetland biomass. 相似文献
12.
城市湿地气候调节功能遥感监测评估 总被引:9,自引:1,他引:9
湿地是地球上最为重要而独特的生态系统类型,在缓解全球气候变化和调节区域气候特征方面具有重要作用。以北京湿地为研究案例,在分析湿地气候调节作用过程机理的基础上,综合运用遥感数据和常规气象站点监测资料,利用CASA模型和植被指数累积模型分别定量反演获得北京湿地年地上生物量和年蒸散量,基于价值量方法定量评估了北京城市湿地气候调节能力。结果表明:①北京湿地地上生物量吸收固定二氧化碳和释放氧气分别约为1.42×108kg和1.03×108kg,价值量分别约为2.83亿元和0.42亿元;②北京湿地蒸散发量约为4.16亿m3,价值量约为1.14亿元。③北京湿地通过固碳释氧和地表蒸散发等过程所形成的气候调节功能总价值约为4.39亿元。 相似文献
13.
It is a very complicated problem to estimate evapotranspiration (ET) over a large area of land surface. In this paper, the evapotranspiration estimation models for dense vegetation and bare soil are presented, based on the information of parameters like vegetation cover-degree and surface albedo. Combined with vegetation cover-degree data, a model for regional evapotranspiration estimation over the heterogeneous landscape is derived. Through a case study using remote sensing data over Northwest China, the accuracy of the model for regional evapotranspiration estimation is checked. The result shows that the accuracy of the model is satisfactory. The features of evapotranspiration over Northwest China are also discussed with the application of the model. 相似文献
14.
1 IntroductionThe method for estimating evapotranspiration (ET) was first given by Dalton in 1802, and a number of models for ET estimation have been presented since then. Those models, from the experiential and semi-experiential models[1,2] and physical models[3,4] to the models in terms of the mechanism for energy and water fluxes in soil-vegetation-atmosphere transfer system such as SiB, have improved the precision of ET estimation. It is, however, difficult to calculate regional ET by … 相似文献
15.
1 IntroductionAs a major part of terrestrial ecosystem, vegetation plays an important role in the energy, matter and momentum exchange between land surface and atmosphere. Through the process of photosynthesis, land plants assimilate carbon in atmosphere and incorporate into dry matter while part of carbon is emitted into atmosphere again through plant respiration. The remainder of photosynthesis and respiration is called net primary productivity (NPP), which is important in the global carbon… 相似文献
16.
This paper discussed the spatial distribution of soil erosion in China at the end of the 20th century based on the second
national soil erosion survey. The result indicated soil erosion is still the prime environmental problem in China. Soil erosion
mainly occurs in the western regions of China, and the slight erosion type, ion the whole, exerts the greatest impact on soil
erosion pattern. The distribution of water erosion shows the impact of landforms: slight water erosion mainly in mountainous
and hilly areas, and half of violent water erosion on the loess landforms. Farmland, forestland and grassland are the major
land use types of slight hydraulic erosion distribution, while the serious hydraulic erosion and slight wind erosion mainly
occur on grassland. Thus, the conservation of the grassland is the key to either hydraulic and wind erosion control. The huangmian
soil (a major type of cultivated soil developed from loess mother material) is the one facing the most serious threat from
soil erosion in Chinas soil resources. Further discussion on the soil erosion distribution still needs more research on the
method and relevant data analysis. 相似文献
17.
This paper discussed the spatial distribution of soil erosion in China at the end of the 20th century based on the second national soil erosion survey. The result indicated soil erosion is still the prime environmental problem in China. Soil erosion mainly occurs in the western regions of China, and the slight erosion type, ion the whole, exerts the greatest impact on soil erosion pattern. The distribution of water erosion shows the impact of landforms: slight water erosion mainly in mountainous and hilly areas, and half of violent water erosion on the loess landforms. Farmland, forestland and grassland are the major land use types of slight hydraulic erosion distribution, while the serious hydraulic erosion and slight wind erosion mainly occur on grassland. Thus, the conservation of the grassland is the key to either hydraulic and wind erosion control. The huangmian soil (a major type of cultivated soil developed from loess mother material) is the one facing the most serious threat from soil erosion in Chinas soil resources. Further discussion on the soil erosion distribution still needs more research on the method and relevant data analysis. 相似文献
18.
准确掌握流域湿地资源的数量和分布, 是流域湿地评价、修复与保护决策的前提。利用“北京一号”小卫星数据对黄河流域2006年湿地格局现状进行了监测, 在GIS技术支持下对流域湿地资源分布的影响控制因素进行了分析, 进而结合不同流域分区水资源条件, 对流域湿地保护策略进行了探讨。研究表明, 2006年黄河流域湿地总面积为25134km2,其中, 河流、湖泊、沼泽、滨海、人工湿地面积分别占该流域湿地总面积的36.2%、8.0%、45.0%、3.9%、6.9%.受气候及水资源支撑条件的影响, 黄河流域重要湿地集中分布在源区高寒沼泽湿地、上游河湖湿地、中下游河道湿地以及河口三角洲湿地。流域天然湿地分布受气候影响显着, 随着气候干燥度的增加, 湿地率呈明显递减趋势。研究认为, 黄河流域大部分地区属于半干旱区, 水资源条件先天不足, 必须充分考虑流域和区域水资源的支撑能力和干扰影响, 在流域层面和河流生态系统的尺度上统筹考虑, 构建科学合理的流域湿地保护框架体系。 相似文献
19.
黄河三角洲农作物种植分区的遥感研究 总被引:9,自引:0,他引:9
本文选取了一年中三个不同时相的TM影像,分别求出了三幅影像的NDVI分布图,将其合成为一幅影像图。由于不同区域种植的作物在三个时相中的NDVI变化是不同的,因此在NDVI合成图上会呈现不同的颜色区域。通过对不同颜色区域进行采样分析,可以确定桃红色区域为冬小麦、玉米(大豆)轮作区,蓝紫色区域为棉花、春玉米、杂粮种植区,亮蓝区域为水稻种植区,亮绿色区域为林地、草地。最后,根据不同颜色区域的NDVI变化特征用非监督分类和监督分类相结合的方法对影像进行了分类提取。这样便可对黄河三角洲农作物的种植情况进行宏观的了解,为农作物种植合理布局及农业可持续发展提供依据。 相似文献