Habitat Selection and Space Partitioning among two Mediterranean Blenniid Species   总被引：4，自引：0，他引：4  

Veronika H.  Koppel 《Marine Ecology》1988,9(4):329-346

Abstract. The utilization of the spatial resources of two syntopic blenniid species - Blennius cunevue and Blennius incognitas - has been investigated in silu and under laboratory conditions. Both species occupy bore holes of the mussel Lithophugu in the sublittoral zone. B. cunevue dominates the more shallow zone (= 0.68 m) and prefers smaller (= 12.76 mm diameter) and horizontal bore holes. B. incognitus inhabits the same depth range as B. cunevue but occupies larger bore holes (= 14.57 mm) in a deeper zone (= 0.86 m). Individuals of B. incognitus do not prefer a special inclination angle. The two blenniid species defend territories with different intraspecific sizes: the mean territory radius of B. cunevue is 6.87 mm, of B. incognitus = 10.95. Mechanisms to reduce competition include different activity rhythm, interspecific social dominance, and differences in territoriality. B. cunevue is the dominant species; its territories arc defended against conspecifics and against B. incognitus.  相似文献   

我国苏北建川潮汐盐沼有孔虫垂直分带的发现和特征     

尤坤元  陈才俊  吴小根  施丙文 《海洋学报》2002,24(1):59-64

通过三个断面加密有孔虫表层采样和精确高程测量,发现建川开敞型盐沼存在特征性盐沼有孔虫组合,这些组合与盐沼植被带相应,受高程控制,有明显的垂直分带,垂直带顶面即最高高潮位以上有孔虫突然消失.这个有孔虫垂直分布模式可高精度地恢复古海面(精度最高可达±5cm).该研究为我国高分辨恢复古海面提供了一个地区性的现代有孔虫标尺,同时该工作也填补了国外仅局限于研究隐蔽型海岸盐沼有孔虫垂直分带的不足.  相似文献   

Vertical differentiation of land cover in the central Himalayas   总被引：1，自引：0，他引：1  

Zhang  Yili  Wu  Xue  Zheng  Du 《地理学报(英文版)》2020,30(6):969-987

Characterized by obvious altitudinal variation, habitat complexity, and diversity in land cover, the Mt. Qomolangma region within the central Himalayas is one of the most sensitive areas to climate change in the world. At the same time, because the Mt. Qomolangma region possesses the most complete natural vertical spectrum in the world, it is also an ideal place to study the vertical structure of alpine land cover. In this study, land cover data for 2010 along with digital elevation model data were used to define three methods for dividing the northern and southern slopes in the Mt. Qomolangma region, i.e., the ridgeline method, the sample transect method, and the sector method. The altitudinal distributions of different land cover types were then investigated for both the northern and southern slopes of the Mt. Qomolangma region by using the above three division methods along with Arc GIS and MATLAB tools. The results indicate that the land cover in the study region was characterized by obviously vertical zonation with the south-six and north-four pattern of vertical spectrum that reflected both the natural vertical structure of vegetation and the effects of human activities. From low to high elevation, the main land cover types were forests, grasslands, sparse vegetation, bare land, and glacier/snow cover. The compositions and distributions of land cover types differed significantly between the northern and southern slopes; the southern slope exhibited more complex land cover distributions with wider elevation ranges than the northern slope. The area proportion of each land cover type also varied with elevation. Accordingly, the vertical distribution patterns of different land cover types on the southern and northern slopes could be divided into four categories, with glaciers/snow cover, sparse vegetation, and grasslands conforming to unimodal distributions. The distribution of bare land followed a unimodal pattern on the southern slope but a bimodal pattern on the northern slope. Finally, the use of different slope division methods produced similar vertical belt structures on the southern slope but different ones on the northern slope. Among the three division methods, the sector method was better to reflect the natural distribution pattern of land cover.  相似文献   

The Umbria–Marche case: some suggestions for the Italian seismic zonation     

L. Peruzza  A. Rebez  D. Slejko  P. L. Bragato 《Soil Dynamics and Earthquake Engineering》2000,20(5-8):361-371

Probabilistic seismic hazard maps, in terms of spectral acceleration and uniform hazard response spectra at given sites, considering local soil conditions, represent a much more complete estimate of the seismic hazard than the traditional maps in terms of peak ground acceleration or macroseismic intensity. This is particularly true when the requests of urban planners and engineers have to be met. The present analysis shows how some hazard parameters, such as the effective peak acceleration and the spectrum intensity, can well synthesise the overall information available from traditional probabilistic studies, but also suggests that soil condition is a first-order ingredient for effective seismic hazard mapping at national level. Three Italian towns, damaged by the 1997 Umbria–Marche earthquake sequence, are considered as example to demonstrate that: (1) soil condition dependent uniform hazard spectra well approximate actual spectra recorded during some events of the seismic sequence; (2) for these localities, the design spectrum of the present Italian seismic code does not seem adequate.

These considerations have induced the Italian scientific community to propose an updating of the national seismic zonation on the basis of several hazard parameters, that are described in this paper.  相似文献   

Identification of different types of harzburgites and their lithofacies zonation in ophiolites : Evidence from the special geological survey of Dingqing ophioliteSCIEI北大核心CSCD     

Li GuanLong  Liu Fei  Yang JingSui  Mu XiaoPing  Zhang ChenJie  Bo RongZhong  Zhang QiZhi 《岩石学报》2022,(11):3375-3390

The ophiolite is an ancient oceanic lithosphere remnant emplaced on the continent, and it is the direct carrier to record the ancient ocean basin from formation to demise. Therefore, the study of ophiolite can provide strong evidence for revealing and restoring the tectonic system and evolution history of ancient oceans and continents. The field geological survey and mapping for ophiolite are the basis for the research on the petrogenesis of chromite, peridotite and oceanic crust units. According to the characteristics of mineral composition, structure and mineral chemistry of harzburgites in Dingqing ophiolite, it is divided into massive, inhomogeneous, pyroxene-oriented, spherulitic and mylonitized harzburgite. Five types of harzburgite were discovered for the first time in the Laraka survey area through 1 : 50000 special geological mapping, and there were obvious lithofacies zoning characteristics in the area of five types of harzburgites. The massive harzburgite lithofacies belts are distributed in the middle of the Laraka survey area, and the inhomogeneous harzburgite lithofacies appear symmetrically on both sides. A small amount of pyroxene-oriented harzburgite lithofacies is distributed in the interior or edge of massive harzburgite facies belt in a lenticular shape, and the production of a very small amount of spheroidal harzburgite is related to basic intrusive rocks. The mylonitized harzburgite lithofacies belt is a slender strip outcropping on the southern margin of the peridotite massif. There is a certain spatial correlation between the distribution, type and scale of chromite deposits or mineralization points and the peridotite facies zoning. More than 20 high -chromium -type chromite deposits are distributed in the inhomogeneous harzburgite, but the massive harzburgite lithofacies have few chromite deposits or mineralizations. The A -A' peridotite lithofacies measured profile in the Lallaka survey area and its corresponding mineral chemical profile further confirm the existence of lithofacies zoning. Cr-spinels in different types of harzburgites show different mineral chemical characteristics. The Cr-# of Cr-spinel in massive harzburgite, in inhomogeneous harzburgite, in pyroxene oriented harzburgite and in the spheroidal harzburgite is 65. 59 similar to 69. 37, 49. 99 similar to 57. 86, 75.19 similar to 85.24 and 57.66 similar to 80.04, respectively. The Cr# of Cr-spinel in inhomogeneous -> massive -> pyroxene-oriented harzburgite gradually increases from 49. 99 to 85.24, indicating that these harzburgite have experienced 23% similar to 43% medium -high partially melted. The mineral chemistry data of massive and pyroxene-oriented harzburgite in the mineral chemistry diagram both fall in the fore -arc peridotite environment, and the inhomogeneous harzburgite falls in the overlapping area of deep-sea and fore -arc peridotite. The Fo of olivine in the spherulite harzburgite is 86.43% similar to 87.05%, and the En of orthopyroxene is 84.66% similar to 85.78%, which are bronzite, indicating magmatic origin. The mylonitized harzburgite is the result of tectonic emplacement of the massif. Different types of peridotite and their lithofacies zoning were identified in the Dingqing ophiolite, which provides a new idea for us to deeply study the multi -stage magmatism of the oceanic lithosphere and the genesis of peridotite and chromite.  相似文献   

基于GIS 的承德市冰雹灾害风险区划     

彭九慧  王多  赵岩  杨庆红 《沙漠与绿洲气象(新疆气象)》2019,13(1):105-109

为了有针对性地防御冰雹灾害,应用承德市精细到乡镇的降雹频次、历史灾情、DEM数据、土地和人口密度等资料,从致灾因子、承灾体、孕灾环境、防灾减灾能力四个方面构建冰雹灾害风险评价模型。运用综合加权分析法和层次分析法计算各指标的权重,通过GIS空间分析技术实现对各评价指标栅格化,制作以栅格为基本评价单元的承德市冰雹灾害风险区划图。结果表明:承德市西北部的丰宁县冰雹灾害风险最高;中北部的围场县、隆化县、平泉县大部、滦平县北部风险较高;承德市南部的兴隆县、宽城县冰雹灾害风险较低。  相似文献   

太行山区牛叫河小流域土地可持续利用模式探讨   总被引：4，自引：0，他引：4  

刘晗  吕斌 《地理研究》2012,31(6):1050-1056

太行山区小流域综合开发治理是促进山区生态建设和保障山前平原城市密集带发展的重大课题。科学划分小流域土地利用功能区,进而形成合理的土地利用模式是推进太行山区小流域开发治理的关键举措。本文以位于太行山东坡的牛叫河小流域为例,界定了生态功能区划的基本程序,建立了包括恒定和波动两类指标的区划指标体系,提出了以模糊聚类为主体的区划方法。将牛叫河小流域划分为分水岭区、沟坡区和沟道区三种土地利用功能类型,相应的土地利用模式为:分水岭区地形平缓,通过改良土壤,可开展农作物种植,统筹安排农林牧业生产;沟坡区地形坡度较大、土地贫瘠,水土流失严重,宜以林为主,并需采取综合保持性措施;沟道区土地平坦,应突破单纯的种植业模式,以获得更高的经济和社会效益。  相似文献   

Influence of water flux and redox conditions on chlorobenzene concentrations in a contaminated streambed     

Christian Schmidt  Marion Martienssen  Edda Kalbus 《水文研究》2011,25(2):234-245

Significant natural attenuation may occur on the passage of groundwater plumes through streambed sediments because of the transition from anaerobic to aerobic conditions and an increased microbial activity. Varying directions and magnitudes of water flow in the streambed may enhance or inhibit the supply of oxygen to the streambed and thus influence the redox zoning. In a field study at a small stream in the industrial area of Bitterfeld‐Wolfen, we observed the variability of hydraulic gradients, streambed temperatures, redox conditions and monochlorobenzene (MCB) concentrations in the streambed over the course of 5 months. During the observation period, the hydrologic conditions changed from losing to gaining. Accordingly, the temperature‐derived water fluxes changed from recharge to discharge. Redox conditions were highly variable between ? 170 and 368 mV in the shallow streambed at a depth of 0·1 m below the streambed surface. Deeper in the streambed, at depths of 0·3 m and 0·5 m, the redox conditions were more stable between ? 198 and ? 81 mV and comparable to those typically found in the aquifer. MCB concentrations in the streambed at 0·3 and 0·5 m depth increased with increasing upward water flux. The MCB concentrations in the shallow streambed at 0·1 m depth appeared to be independent of the hydrologic conditions suggesting that degradation of MCB may have occured. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

关于在辽宁省执行国家标准《中国地震动参数区划图》的几点看法     

钟以章  牛雪 《东北地震研究》2001,17(4):70-75

本文简要介绍了国家标准《中国地震动参数区划图》的内容、特点，并就如何在辽宁省执行该国家标准提出了几点看法。  相似文献   

二连盆地巴音都兰凹陷早白垩世构造岩相带特征及含油性   总被引：6，自引：4，他引：6       下载免费PDF全文

崔周旗  吴健平  李莉  王海潮 《古地理学报》2001,3(1):25-34

在系统观察岩心的基础上，从单井相分析入手，结合地震相和测井相模式，以及大量岩矿、粒度等分析化验资料，对巴音都兰凹陷下白垩统巴彦花群的物源方向、沉积体系、构造岩相带及含油性进行了研究。认为区内具有东、西两大物源区、五大水系控制着十一个砂体的平面展布，最终，划分了扇三角洲等五种沉积体系，总结出具平台型陡坡扇三角洲等六种构造岩相带，并着重对有别于典型单断箕状凹陷的三种构造岩相带的含油性进行了初步探讨。  相似文献