近海海面上水汽向上输送的季节性差异     

陈绍鑫 《海洋湖沼通报》1994,(2):202-207

本文分析了雷达观测结果，发现近海海面上的水汽向上输送随季节而变化，由于季节的变化和不同的天气情况，海表面大气现象在雷达中有不同的显示，根据这些显示得到了不同的信息，由此而得出春秋两季海表面水汽向上输送量的不同。  相似文献   

海带几个不同种的雌性克隆对高温的适应力     

王梅林 《中国海洋大学学报(自然科学版)》1987,(2)

每几个不同种的雌性克隆对高温(22℃、24℃、26℃)的适应力有所差异。大西洋沿岸的Laminariahyperhoren和L.sacchrina雌性克隆较太平洋沿岸的L.japonica、L.angustata和L.ochotensis雌性克隆明显地不耐高温,遗传性的不同是造成这种差异的主要原因。这种遗传性差异是海带长期自然选择的结果。同一物种L.japonica和L.japonicaCⅡ两种雌性克隆在24℃条件下,在第24天其死亡率分别是40.2％和25.2％,X~2=12.25,P<0.001,差异是高度显著的,说明这种不同是遗传性不同所致,而且属于物种内部的差异。  相似文献   

A conceptual framework for marine biodiversity and ecosystem functioning   总被引：1，自引：0，他引：1  

Ferdinando Boero  & Erik Bonsdorff 《Marine Ecology》2007,28(S1):134-145

  相似文献   

干旱区植被生态需水理论研究进展   总被引：7，自引：0，他引：7  

胡广录  赵文智  谢国勋 《地球科学进展》2008,23(2):193-200

综述了植被生态需水的概念及其内涵,评价了植被生态需水的主要研究理论——生态适宜性理论、系统阈值理论、水文循环水量平衡理论、农业气象学理论,评析了各种理论在实践应用中的优缺点。指出在未来的植被生态需水研究中应加强生态体系健康标准建立、定量评价指标体系的数值模拟模型构建,研究中还必须注重植被生态需水的时空特性,充分利用“3S”技术手段和先进的科学试验设备,全方位、多角度获取不同研究区域的基础信息,为建立植被生态需水理论提供可靠的数据支撑。  相似文献   

Approaches for comparative evaluation of raster GIS-based landslide susceptibility zonation maps     

R.P. Gupta  D.P. Kanungo  M.K. Arora  S. Sarkar 《International Journal of Applied Earth Observation and Geoinformation》2008

Evaluation of maps generated from different conceptual models or data processing approaches at spatial level has importance in many geoenvironmental applications. This paper addresses the spatial comparison of different landslide susceptibility zonation (LSZ) raster maps of the same area derived from various procedures.  相似文献   

A sub-pixel analysis of urbanization effect on land surface temperature and its interplay with impervious surface and vegetation coverage in Indianapolis,United States     

Qihao Weng  Dengsheng Lu 《International Journal of Applied Earth Observation and Geoinformation》2008

This study developed an analytical procedure based upon a spectral unmixing model for characterizing and quantifying urban landscape changes in Indianapolis, Indiana, the United States, and for examining the environmental impact of such changes on land surface temperatures (LST). Three dates of Landsat TM/ETM+ images, acquired in 1991, 1995, and 2000, respectively, were utilized to document the historical morphological changes in impervious surface and vegetation coverage and to analyze the relationship between these changes and those occurred in LST. Three fraction endmembers, i.e., impervious surface, green vegetation, and shade, were derived with an unconstrained least-squares solution. A hybrid classification procedure, which combined maximum-likelihood and decision-tree algorithms, was developed to classify the fraction images into land use and land cover classes. Correlation analyses were conducted to investigate the changing relationships of LST with impervious surface and vegetation coverage. Results indicate that multi-temporal fraction images were effective for quantifying the dynamics of urban morphology and for deriving a reliable measurement of environmental variables such as vegetation abundance and impervious surface coverage. Urbanization created an evolved inverse relationship between impervious and vegetation coverage, and brought about new LST patterns because of LST's correlations with both impervious and vegetation coverage. Further researches should be directed to refine spectral mixture modeling by stratification, and by the use of multiple endmembers and hyperspectral imagery.  相似文献   

基于神经网络方法的芦苇叶面积指数遥感反演   总被引：2，自引：0，他引：2  

陈健  倪绍祥  李云梅 《国土资源遥感》2008,(2):62-67

提出了一种从TM图像上获取芦苇冠层叶面积指数的方法:首先对芦苇的生长背景进行分类;然后,对不同的背景光谱利用冠层反射率(FCR)模型计算得到查找表;最后,利用实测数据和查找表中的数据作为参数进行BP神经网络模型训练,从而得到芦苇冠层LAI。结果表明,人工神经网络方法有很强的非线性拟合能力,能够消除背景对反演结果的影响,有效提高LAI反演的精度。  相似文献   

煤炭城市生态环境可持续发展研究--以淮南市为例     

邢琴琴  焦华富  尹乐 《世界地理研究》2006,15(2):54-60

根据城市生态学原理和方法,针对煤炭城市生态环境特点,构建了能够体现煤炭城市生态环境质量主要特征的,定性、定量考核的评价指标体系。利用层次分析、变权综合指数等方法,建立了煤炭城市生态环境质量综合评价模型。从自然、经济、社会三个方面对淮南市生态环境质量进行评价,并对淮南市生态环境可持续发展提出了相应对策。  相似文献   

Soil quality changes in land degradation as indicated by soil chemical, biochemical and microbiological properties in a karst area of southwest Guizhou, China   总被引：7，自引：0，他引：7  

Pingjiu Zhang  Lianqing Li  Genxing Pan  Jingchen Ren 《Environmental Geology》2006,51(4):609-619

Not only the nutritional status and biological activity but also the soil ecological functioning or soil health has been impacted profoundly by land degradation in the karst area of southwest China where the karst ecosystems are generally considered as extremely vulnerable to land degradation under intensified land-use changes. The objectives of this study are to elucidate the changes in overall soil quality by a holistic approach of soil nutritional, biological activity, and soil health indicators in the karst area as impacted by intense cultivation and vegetation degradation. Topsoil samples were collected on selected eco-tesserae in a sequence of land degradation in a karst area of southwest Guizhou in 2004. The soil nutrient pools of organic carbon (C_org), extractable extracellular carbon (C_ext), total soil nitrogen (N_t), alkali-hydrolyzable nitrogen (N_ah), total phosphorus (P_t), available phosphorus (P_a) were analyzed by wet soil chemistry. The soil biological properties were studied by means of measurements of microbial biomass carbon (both by fumigation–extraction, FE-C_mic, and by calculation from substrate-incubation respiration, SIR-C_mic) of respiration [respiration without addition of substrates, basal respiration (BR), and potential respiration (PR) with substrate-incubation] and of soil enzyme activities (invertase, urease, and alkaline phosphatase). Soil health status was assessed by simple indices of C_mic/C_org and BR/C_mic in conjunction with bacterial community structures determined by polymerase chain reaction and denaturing gradient gel electrophoresis. While the nutritional pool parameters, such as C_org and C_ext, described basically the changes in soil life-supporting capacity with cultivation interference and vegetation declined, those parameters of biological activity such as FE-C_mic, SIR, and SIR-C_mic as well as bacterial community structures measured by molecular method evidenced well the changes in soil functioning for ecosystem health with the land degradation.  相似文献   

Effect of supplemental feeding on spatial distribution and browse utilization by white-tailed deer in semi-arid rangeland     

S.M. Cooper  M.K. Owens  R.M. Cooper  T.F. Ginnett   《Journal of Arid Environments》2006,66(4):716-726

We investigate the risk that supplemental feeding of white-tailed deer (Odocoileus virginianus) to improve trophy quality may degrade rangeland through overutilization of forage plants near the feeders. We divided a South Texas ranch into 6 areas (each 1100 ha). Supplemental feed was provided year-round in a centrally placed feeder in 3 areas, no supplement was provided in the 3 control areas. Radio-telemetry collars were fitted on 2 bucks and 2 does in each area. Spatial distribution of these deer was assessed using the CALHOME program. Feed supplementation did not alter home range size of does but did reduce their 50% core area. Bucks without supplemental feed showed 2 spatial strategies; sedentary bucks had home range distributions similar to supplemented bucks, while commuter bucks moved to supplemented areas during the breeding season. Browsing pressure near feeders and control sites was assessed by measuring consumption of seedlings set in arrays radiating from feeders and control points. Deer browsing was heavier near feeders than at the control sites, and the probability of a seedling being browsed increased with proximity to the feeder. We caution against long-term supplemental feeding in fixed locations because of the potential for localized range degradation around the feeders.  相似文献