两种植被指数与地表温度定量关系的比较研究——以南京市为例

加强绿化可有效缓解城市热岛（UHI）效应,但植被降温规律如何,如何科学绿化一直模糊不清。以南京市ETM+影像为数据源,经ATCOR2模块大气校正后,提取了南京城区地表温度（LST）、归一化植被指数（NDVI）和减化比值植被指数（RSR）,基于实测值和同时相ASTER数据反演结果的双重验证,拟合了两种植被指数与地表温度的定量关系,并进行了对比研究。结果表明：南京市存在明显的UHI,城区水体和绿地为显著的低温区,除水体外,植被覆盖度高的区域地表温度明显低于植被稀少或无植被区;地表温度与NDVI呈显著线性负相关,与RSR呈显著幂函数负相关,后者的相关性高于前者;以〖WTBX〗RSR〖WTBZ〗=32为界,此值之前,地表温度随着植被覆盖增加而锐减,此值之后,植被覆盖继续增加,地表温度却趋于恒定,呈现植被降温效应“饱和”现象;RSR能直接说明对于不同下垫面,增加相同的植被覆盖度其降温效果存在差异,而不进行土地利用分类,NDVI无法揭示此现象     

退化山地植被恢复和重建的基本理论和方法

退化植被恢复和重建已成为我国农村社会经济环境持续发展面临的迫切任务,提出了人工恢复和退建退化山地植被的基本方法论。退化山地植被和重建必需以兼顾退化 治理和农村经济发展,建设生态经济型植被为目标,阐述了在恢复和重建过程中应的九项生态学原理和芾项技术方法,介绍了诊断一玫方案一物种选择－各种植物 群的设计及其组合与实施－监测和进一步优化调控等基本人工恢复和重建退化地山植被的步骤。该方法论已在岷江上游的在     

铜陵铜尾矿复垦现状及植物在铜尾矿上的定居

安徽省铜陵市位于长江中游,是我国主要的铜矿产区,其铜尾矿共有5个主要的分布区域。随排放时间的延长,各尾矿库的持水保肥能力和植被覆盖率提高;铜尾矿限制植物定居的主要因素是极端贫瘠和重金属毒性,各尾矿库的重金属含量都很高,而N 、P、K和有机质的含量很低甚至为零。自然和人工定居于尾矿上的植物共有9 科37 属40种,其中禾本科、豆科、菊科植物占所有植物种的72.5%,此3科植物因有完美的生态适应机制而能成为在尾矿上定居的先锋植物和优势种。铜尾矿库植被自然演替属于几十年甚至上百年的长期演替,铜矿废弃地的治理和恢复重建更是一项长期而艰巨的工作。     

南水北调中线水源地不同植被类型坡地土壤水分特征研究——以秦岭南坡宁陕县寨沟小流域为例

为了解不同植被类型土壤水资源的变化规律,选择南水北调中线水源区宁陕县寨沟区域典型植被针阔混交林、针叶林、板栗林、灌木林、荒坡草地和坡耕地为研究对象,通过样地调查与实验分析的方法对其土壤水分物理特征及有机质含量进行测定研究.结果表明,各种有林地的土壤容重、孔隙度和有机质等理化特征均优于荒坡和坡耕地;针阔混交林土壤含水量最高,蓄水能力明显好于其它植被类型;在垂直剖面上,各种植被类型坡地土壤含水量和饱和蓄水量随土壤深度的增加基本呈递减趋势,但有林地下降幅度较大,表层含水量明显高于荒坡与坡耕地表层.由此可见,在涵养水源方面,针阔混交林最好,针叶林、板栗林与灌木林次之,荒坡与坡耕地较差.     

城市河涌污染治理技术的研究进展

随着经济的高速发展,大量污染物排放于城市河涌,导致城市河涌受到严重的污染。采取有效的技术措施治理河涌污染势在必行。结合近年来国内外河涌治理的研究成果,综述了河涌治理的主要技术的原理、特点、存在的问题,并指出目前各项技术的研究重点。     

湖库水生植被光学遥感监测研究进展和展望

水生植被在湖库生态系统中发挥稳定沉积物、净化水质、平衡水生生态系统等作用,监测水生植被变化对湖库生态环境的监测具有重要意义。梳理了国内外利用高光谱、多光谱光学卫星遥感数据提取湖库水生植被的方法,尤其是针对其中涉及的阈值确定问题进行总结分析,介绍了典型研究区水生植被时空分布和变化以及与水质的关系,最后给出一些水生植被遥感监测的展望。     

Evaluation of Methods for Delineating Riparian Zones in a Semi‐Arid Montane Watershed

Riparian zones in semi‐arid, mountainous regions provide a disproportionate amount of the available wildlife habitat and ecosystem services. Despite their importance, there is little guidance on the best way to map riparian zones for broad spatial extents (e.g., large watersheds) when detailed maps from field data or high‐resolution imagery and terrain data are not available. Using well‐established accuracy metrics (e.g., kappa, precision, computational complexity), we evaluated eight methods commonly used to map riparian zones. Focusing on a semi‐arid, mountainous watershed, we found that the most accurate and robust method for mapping riparian zones combines data on upstream drainage area and valley topography. That method performed best regardless of stream order, and was most effective when implemented with fine resolution topographic and stream line data. Other commonly used methods to model riparian zones, such as those based on fixed‐width buffers, yielded inaccurate results. We recommend that until very‐high resolution (<1 m) elevation data are available at broad extents, models of riparian zones for semi‐arid mountainous regions should incorporate drainage area, valley topography, and quantify uncertainty.     

Inter-observer variation in habitat survey data: investigating the consequences for professional practice

Environmental assessments and land-use planning require reliable information on the botanical composition and distribution of habitats. There have been numerous academic studies of inter-observer variation in species-inventory and habitat mapping, but studies addressing the prevalence of inter-observer variation and consequences of poor quality data in professional practice are lacking. This paper addresses these questions via a questionnaire survey of environmental professionals, using the standard Phase 1 and National Vegetation Classification (NVC) survey methods in the United Kingdom. The survey revealed that misidentification of habitat types within survey reports was relatively common (approximating to 20% of all reports seen by respondents over the previous five years). Approximately 40% of respondents who had encountered erroneous reports stated that these had led to inaccurate initial site ecological assessments. Additional field surveys and discussions with surveyors were commonly used to resolve these issues, but for Phase 1 and NVC 26% and 34% of respondents, respectively, had encountered one or more cases where errors resulted in negative consequences for clients commissioning surveys (in terms of extra costs and project delays). Net loss of biodiversity arising from inaccurate reports was reported in at least one instance by 32% and 38% of respondents for Phase 1 and NVC surveys, respectively – results that may contribute to the attrition of natural capital within the UK. The study highlights the need to extend studies of inter-observer variation to consider impacts on environmental assessments and decision-making in professional practice. The potential benefits of introducing an accreditation scheme (favoured by the majority of respondents to the questionnaire) are discussed.     

Characterizing Runoff and Water Yield for Headwater Catchments in the Southern Sierra Nevada

In a Mediterranean climate where much of the precipitation falls during winter, snowpacks serve as the primary source of dry season runoff. Increased warming has led to significant changes in hydrology of the western United States. An important question in this context is how to best manage forested catchments for water and other ecosystem services? Answering this basic question requires detailed understanding of hydrologic functioning of these catchments. Here, we depict the differences in hydrologic response of 10 catchments. Size of the study catchments ranges from 50 to 475 ha, and they span between 1,782 and 2,373 m elevation in the rain‐snow transitional zone. Mean annual streamflow ranged from 281 to 408 mm in the low elevation Providence and 436 to 656 mm in the high elevation Bull catchments, resulting in a 49 mm streamflow increase per 100 m (R² = 0.79) elevation gain, despite similar precipitation across the 10 catchments. Although high elevation Bull catchments received significantly more precipitation as snow and thus experienced a delayed melt, this increase in streamflow with elevation was mainly due to a reduction in evapotranspiration (ET) with elevation (45 mm/100 m, R² = 0.65). The reduction in ET was attributed to decline in vegetation density, growing season, and atmospheric demand with increasing elevation. These findings suggest changes in streamflow in response to climate warming may likely depend on how vegetation responds to those changes in climate.     

水利水电工程建设对荒漠河岸林草的影响分析研究

以新疆喀什噶尔河流域克孜河卡拉贝利水利枢纽工程为例,采用水均衡模型计算方法,从工程建成后区域荒漠河岸林草耗水量变化、荒漠河岸林草区地下水位变化情况、工程建成后洪水过程变化等方面分析工程建设对工程影响区荒漠河岸林草的影响。评价结果显示,工程建成后,与现状相比荒漠河岸林草植被的耗水量有所增加,区域平均地下水埋深仍能维持现状,在河岸林草生长和繁殖的6-9月,区域地下水位较现状略有上升,可满足大部分荒漠河岸林草植被的正常生长需求,水库对5年一遇标准以下洪水不调蓄,不会对荒漠河岸林草的繁衍存活产生明显不利影响。