淋洗脱盐对滨海滩涂不同植被演替带土壤重金属的影响

为研究围垦对滨海滩涂土壤重金属的影响,采用土柱实验模拟淋洗脱盐过程,分析了滨海滩涂不同植被演替带(光滩、互花米草滩、碱蓬滩、芦苇滩)土壤在淋洗脱盐前后重金属(As、Hg、Cd、Cr、Pb、Cu、Zn)含量的变化,评估了围垦可能导致的滩涂重金属流失量。研究表明,淋洗脱盐后,各植被演替带土壤重金属均显著降低,相比而言,Hg、Cr更易淋洗(淋洗率分别为57.2%、49.9%),而Zn不易淋洗(淋洗率18.5%);不同植被演替带土壤重金属淋洗率表现为:光滩互花米草滩碱蓬滩芦苇滩,光滩土壤重金属更易淋洗,而芦苇滩重金属不易淋洗;根据土壤容重、含水率、淋洗率及重金属含量计算重金属流失量发现,不同植被演替带重金属流失量同样表现为:光滩互花米草滩碱蓬滩芦苇滩;除互花米草滩As流失量较高外(19.26 kg·ha-1),其他重金属流失量均表现为光滩最高,光滩围垦可能会造成更多的重金属流失;在仅考虑淋洗脱盐情况下,以江苏省2010~2020年围垦规划270万亩计,仅表层20 cm滩涂土壤,通过围垦即可能导致As、Hg、Cd、Cr、Pb、Cu、Zn流失2 102.5、7.4、421.3、8 587.9、4 376.3、2 404.3 t,由围垦导致的滩涂重金属流失风险值得关注。     

2000-2019年中国北方地区沙尘暴时空变化及其相关影响因素

利用多年多源环境、气象和卫星遥感资料,从年代际、年际异常和气候变化的角度分析了21世纪以来中国北方地区沙尘暴的时空演化特征及其气象、植被变化的影响机理.结果表明：①2000—2013年中国北方地区沙尘暴年日数呈显著波动下降趋势,下降速率为1.1 d/10 a,2013年后呈微弱增长趋势.近40年来,春季沙尘暴日数占全年沙尘暴日数的平均占比为62%,但其逐年变化率明显下降（-7.3%/10 a）,2010年后夏季沙尘暴日数的变化率则呈现上升趋势（12.4%/10 a）,新疆塔克拉玛干沙漠地区沙尘暴的高发季节由春季逐渐向夏季扩展.②21世纪初中国北方地区沙尘暴发生频数明显下降,沙尘暴影响范围向塔克拉玛干沙漠南部地区收缩西移,戈壁沙漠在亚洲沙尘源区中的主体地位逐年下降,改变了中国北方地区沙尘暴的空间格局.③中国北方地区沙尘暴的区域性减少主要归因于平均风速与大风日数逐年下降（-0.1 m·s^-1/10 a、-4.4 d/10 a）、年降水量显著增加（32.7 mm/10 a）及区域地表变绿.塔里木盆地南缘局地风速的升高是导致该地区沙尘暴多发的重要气象影响因素,而地表植被覆盖的增加是造成戈壁沙漠沙尘暴年日数显著下降的主要原因.     

石羊河流域的生态环境问题、引发原因与治理对策

石羊河是甘肃省三大内陆河之一,在河西乃至全省经济社会发展中起着十分重要的作用.目前该流域出现森林面积减少,雪线上升,水土流失加重,地下水位下降,水体污染,水质恶化,荒漠化蔓延等一系列生态环境问题,已经严重影响和制约到流域及其周边地区的经济建设和社会安定团结.为实现流域生态大系统及其子系统稳定、健康、持续发展,应坚持"南保水源,中建绿洲,北治风沙"的基本原则.对流域大系统,要切实加强流域水资源统一管理,完善政策体系,加强环境保护的执法、宣传,提高流域民众的生态意识,加强生态建设工程的科技支撑.对流域南部祁连山区,要加强林区管理,理顺体制,加强山区植被保护和建设,提高水源涵养能力,减少水土流失,合理调整水库,减少汛期蓄水.对中部绿洲,要发展二三产业,加快小城镇建设,调整农业产业结构,加强农田防护林体系建设,加大节水力度,实施外流域调水工程.对北部荒漠区,要恢复、重建退化固沙植被,退耕还草还荒,严禁新的土地开垦,适度发展沙产业.     

Estimating the opportunity costs of biodiversity protection in the Brigalow Belt, New South Wales

The New South Wales Government recently introduced the Native Vegetation Conservation Act to protect the native grassland and woodland of the state. The Act protects biodiversity by preventing farmers from clearing such vegetation on their properties but, as a consequence, reduces farm incomes and land values. An economic model of the relationship between land value and percentage of farm in native vegetation is integrated with an ecological model of the relationship between species lost and percentage of the farms in native vegetation. The integrated framework is applied to estimate the opportunity costs of the Act for one important agricultural area of the state, the northern part of the Brigalow Belt South Bio-Region. If all the vegetation were protected, the reduction in land value would be at least 14.3%, which is an opportunity cost of at least 148.5 dollars m for the area. Both the benefits and costs of biodiversity protection must be accounted for, so risk simulations are then combined with benefit-cost analysis to compare the benefits of biodiversity protection to these costs.     

Monitoring of Aquatic Macrophytes for Detection of Long-term Change in River Systems

This paper presents details of the methodology developed by the United Kingdom's Environmental Change Network for the long-term monitoring of macrophytes in rivers and streams. The methodology is based on techniques first proposed by the Standing Committee of Analysts (1987) and later adapted by the National Rivers Authority (NRA) and Environment Agency, but differs in splitting the surveyed 100 m stretch of waterinto sections to provide an objective measure of the frequencyof occurrence of individual species in place of the moresubjective estimation of cover. A pilot study of the ECN methodology took place at five sitesin 1997. The results of this study, including a few practicaldifficulties in the application of the methodology, are presented and discussed. For all but one of the sites strongassociations were found between the number of species observedand the physical characteristics of the watercourse. The most important characteristics were degree of shading, substrate type, depth and clarity. The frequency of occurrence of individual species within sections of the watercourse was foundto be strongly related to the log of the overall estimates of cover. Because the use of sections, rather than a single overall coverestimate, enables variation in the pattern of vegetation over surveyed stretches to be detected and related to watercourse characteristics, the precision with which change can be detected is increased, and the possibility of determining the causes of change is thereby enhanced. Moreover the use of sections allows within-site variation to be calculated and hence the accuracy of estimated changes to be quantified.In general implementation of the ECN methodology was not found to be particularly onerous or difficult. As a result of the pilot study some changes in the ECN methodology have been made, primarily to reduce the workload so that sites can be surveyed comfortably in a single day.     

Exploratory visualization software for reporting environmental survey results

Environmental surveys yield three principal products: maps, a set of data tables, and a textual report. The relationships between these three elements, however, are often cumbersome to present, making full use of all the information in an integrated and systematic sense difficult. The published paper report is only a partial solution. Modern developments in computing, particularly in cartography, GIS, and hypertext, mean that it is increasingly possible to conceive of an easier and more interactive approach to the presentation of such survey results. Here, we present such an approach which links map and tabular datasets arising from a vegetation survey, allowing users ready access to a complex dataset using dynamic mapping techniques. Multimedia datasets equipped with software like this provide an exciting means of quick and easy visual data exploration and comparison. These techniques are gaining popularity across the sciences as scientists and decision-makers are presented with increasing amounts of diverse digital data. We believe that the software environment actively encourages users to make complex interrogations of the survey information, providing a new vehicle for the reader of an environmental survey report.     

利用遥感影像软件ENVI提取植被指数

在遥感影像处理中，植被指数提取广泛应用于定性和定量评价植被覆盖及其生长活力。主要介绍了在ENVI遥感图像处理软件对遥感影像进行植被指数。对植被指数提取的关键部分进行分析，并给出植被指数提取的技术关键。     

基于遥感信息的沙漠化灾害程度定量提取研究

在分析沙漠化等级遥感信息提取现状的基础上,根据遥感手段沙漠化等级综合标志,提出了植被盖度分割和缨帽变换分割两种沙漠化程度遥感信息提取方法,并将其与传统的监督分类进行了比较.认为监督分类精度最低,植被盖度分割和缨帽变换分割更适用于生态环境动态监测,而在水体分布区缨帽变换分割较植被盖度分割适用.     

基于知识的多时相TM图像森林火烧迹地快速提取方法

本文以覆盖福州市及周边地区的五期TM图像为例,进行森林火烧迹地的自动提取研究.分别对TM图像上火烧迹地及其背景地物采样,分析火烧迹地在TM图像6个波段及PC变换、TC变换、多时相植被指数(MTVI)上的光谱特征,发现了火烧迹地与背景地物区分的光谱知识.其次,利用DEM数据分析火烧迹地在地形上的分布特点,发现了火烧迹地空间分布的知识规则.在此基础上建立了基于知识的多时相TM图像上森林火烧迹地提取模型,从而解决了快速识别和提取森林火灾信息的问题.