利用植被供水指数法监测干旱的研究

利用FY-1D/AVHRR数据通道1、2的反射率计算植被指数和通道4、5的亮温计算作物冠层温度,进而求出植被供水指数可监测干旱状况.本文简单介绍了利用FY-1D/AVHRR数据植被供水指数法监测生长季的干旱状况.研究表明,该方法所得结果从总体趋势看,与实际情况基本吻合.因此,植被供水指数法适用于生长季大范围的干旱监测.     

天津盘山风景名胜区植被覆盖状况

以天津国家级盘山风景名胜区为研究区,利用2004-2007年覆盖天津国家级盘山风景区的中巴资源卫星数据,用主成分变换方法,对原始CCD影像进行提取,与归一化植被指数(NDVI)相结合,进行土地利用/土地覆盖(LULC)的提取。通过研究发现,2007年6月项目区植被面积为85 km2,9月为97 km2,与2004、2005年同期植被面积相比均有较大变化。     

三峡库区土地覆被动态变化遥感分析

利用 1 995年和 2 0 0 0年TM卫星影像资料 ,对三峡库区 5年内的土地覆被动态变化进行了分析。结果表明 ,该时期库区土地覆被的变化主要表现为林地向草地和耕地转化 ,以及耕地向建设用地转化 ;其次是林地向建设用地转化 ,有林地向灌丛转化 ,以及草地向林地转化。土地覆被的这种变化说明 ,三峡库区近几年来生态环境在总体上呈现继续恶化的趋势 ,仅局部地区有所好转。     

Seasonal and spatial variability of polychlorinated biphenyls (PCBs) in vegetation and cow milk from a high altitude pasture in the Italian Alps

The seasonal and spatial variability of polychlorinated biphenyls (PCBs) in vegetation and cow milk was studied in a high altitude pasture in the Alps (1900 m a.s.l.). PCB contamination in vegetation shows a concentration peak in June, which is mainly interpreted as the consequence of a temporary PCB enrichment of the air layer above the ground due to net emission fluxes from the soil. A three compartment dynamic model was developed to test this hypothesis. The North/South enrichment factor in the vegetation was 1.5-1.6 for penta- and hexa-substituted congeners and 1.7 for hepta- and octa-PCBs, according to the effect of temperature on compounds having higher K_oa values. Milk concentrations followed the vegetation seasonal trend. The congener abundance in milk is in agreement with the biotransformation susceptibility, absorption efficiency and residence time of the different congeners in dairy cows.     

华北地区城市绿地固碳能力测算研究

文章通过对位于华北地区的7个案例的城市绿地植被固碳能力的研究,形成一套系统的计算方法.结果表明:适用于雄安新区的城市绿地单位面积固碳能力约为2.62 kg/a m2;各个植被群落的固碳能力从大到小依次为乔木(2.66kg/am2)、灌木(2.59kg/a·m2)、地被(2.01 kg/a·m2).研究结果将为实现城市绿...     

Mapping Grazing-Induced Degradation in a Semi-Arid Environment: A Rapid and Cost Effective Approach for Assessment and Monitoring

Improved techniques for measuring and monitoring the state of biodiversity are required for reporting on national obligations to international and regional conservation institutions. Measuring the extent of grazing-related degradation in semi-arid ecosystems has proved difficult. Here we present an accurate and cost-effective method for doing this, and apply it in a South African semi-arid region that forms part of a globally significant biodiversity hotspot. We grouped structurally and functionally similar vegetation units, which were expert-mapped at the 1:50,000 scale, into four habitat types, and developed habitat-specific degradation models. We quantified degradation into three categories, using differences between dry and wet season values of the Normalized Difference Vegetation Index (NDVI) for the three succulent karoo habitats, and the difference between maximum and mean NDVI values for the subtropical thicket habitat. Field evaluation revealed an accuracy of 86%. Overall, degradation was high: 24% of the study area was modeled as severely degraded, and only 9% as intact. Levels of degradation were highest for bottomland habitats that were most exposed to grazing impacts. In sharp contrast to our methods, a widely used, broad-scale and snapshot assessment of land cover in South Africa was only 33% accurate, and it considerably underestimated the extent of severely degraded habitat in the study area. While our approach requires a multidisciplinary team, and in particular expert knowledge on the characteristics and spatial delimitation of vegetation types, it is repeatable, rapid, and relatively inexpensive. Consequently, it holds great promise for monitoring and evaluation programs in semi-arid ecosystems, in Africa, and beyond.     

Understanding large-scale deforestation in southern Jinotega, Nicaragua from 1978 to 1999 through the examination of changes in land use and land cover

Nicaragua, home to the largest remaining extent of rainforest in Central America (total surface area) and to a significant indigenous population, has lost approximately half of its forest cover since 1950. This major and rapid loss of forest cover has been explained as the consequence of an eastward moving agricultural frontier that cuts through the region of Jinotega. If the current deforestation rate continues, the country could lose its remaining forest cover over the course of the next two decades; therefore, it is essential that the dynamics and relationships of land-use and land-cover change (LUCC) in this region are understood. To examine LUCC in Nicaragua over time, Landsat imagery from the southern portion of the region of Jinotega, taken in 1978, 1987, and 1999 was utilized. A remote-sensing method, supervised classification, which allows for the grouping of spectrally similar values for each year, followed by an image change detection analysis (postclassification comparison) was conducted. Groundtruthing (field validation) was conducted in 2006 to validate the data, which yielded increasing overall accuracy rates of 71.68% for 1978, 82.35% for 1987, and 84.38% for 1999. The classification and change detection results showed that if the agricultural cultivation overtook this region, it happened before 1978. Therefore, the possibility that either deforestation did not actually occur along an agricultural frontier or that it was located further east exists; this would be an interesting subject for future studies. There was, however, clear evidence of increased forest cover from 1987 to 1999 near the urban center, correlating with the enforced reforestation law in the city of Jinotega.     

长江上游不同地形条件下的土地利用/覆盖变化

基于1〖DK〗∶10万的1980、2000和2005年的土地利用/覆盖数据和90 m分辨率的DEM数据,采用转移概率矩阵和地形 面积频度方法,分析了1980~2005年长江上游地区不同地形因子条件下的土地利用/覆盖变化。结果表明：1）1980~2000年,草地、林地和农业用地面积变化趋势与2000~2005年相反。后5 a,可能由于退耕的土地出现反弹现象增多,草地和林地面积出现缩减而农业用地面积增加。两个分析时段主要的土地利用/覆盖类型变化趋势类似,包括农业用地向林地和草地的转化,林地向农业用地的转化以及草地向裸地的转化。2）农业用地和城镇用地主要分布于低海拔区而林地、草地则主要分布于高海拔区。低海拔区主要是退耕还林和城市化过程。高海拔区主要是林地的退化消失和草地退化沙化过程。3）农业用地在坡度段10~25°所占面积比例最大。林地用地面积比例随坡度变陡呈现规则递增,城镇用地分布趋势与之相反。近年裸地趋向分布于缓坡区。坡度0~5°的区域主要是草地退化沙化过程;5~10°坡度段主要是退耕还林过程;大于10°的区域造林工程与森林退化并存。4）各种土地利用/覆盖类型对不同坡向的适宜性相差不大。各种坡向上土地利用/覆盖类型变化类似.     

Is tourism damaging ecosystems in the Andes? Current knowledge and an agenda for future research

Despite the popularity of tourism and recreation in the Andes in South America and the regions conservation value, there is limited research on the ecological impacts of these types of anthropogenic use. Using a systematic quantitative literature review method, we found 47 recreation ecology studies from the Andes, 25 of which used an experimental design. Most of these were from the Southern Andes in Argentina (13 studies) or Chile (eight studies) with only four studies from the Northern Andes. These studies documented a range of impacts on vegetation, birds and mammals; including changes in plant species richness, composition and vegetation cover and the tolerance of wildlife of visitor use. There was little research on the impacts of visitors on soils and aquatic systems and for some ecoregions in the Andes. We identify research priorities across the region that will enhance management strategies to minimise visitor impacts in Andean ecosystems.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-014-0550-7) contains supplementary material, which is available to authorized users.     

Short‐Term Effects of Hydrogen Fluoride on Nicotiana tabacum L

Data on the short‐term effects of fumigation with hydrogen fluoride (HF) on the response behavior of the Nicotiana tabacum L. cv. St. Karabalar 6265 are being presented. Growth rate, fluoride accumulation in leaves and soils, and degradation in chlorophyll and nicotine contents of the plant species against the variations in two experimental factors, namely the exposure concentration and exposure time parameters, were investigated. Resulting data reveals that the variety selected for this study is not so tolerant to fluoride as generally reported in the literature, if only the individual effects of the pollutant is considered.