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1.
Globally, priority areas for biodiversity are relatively well known, yet few detailed plans exist to direct conservation action within them, despite urgent need. Madagascar, like other globally recognized biodiversity hot spots, has complex spatial patterns of endemism that differ among taxonomic groups, creating challenges for the selection of within-country priorities. We show, in an analysis of wide taxonomic and geographic breadth and high spatial resolution, that multitaxonomic rather than single-taxon approaches are critical for identifying areas likely to promote the persistence of most species. Our conservation prioritization, facilitated by newly available techniques, identifies optimal expansion sites for the Madagascar government's current goal of tripling the land area under protection. Our findings further suggest that high-resolution multitaxonomic approaches to prioritization may be necessary to ensure protection for biodiversity in other global hot spots.  相似文献   

2.
Many differences in the ring-width growth within a tree may be attributed to changing supplies of food and hormones. In moist sites or during periods of favorable climate, there may be sufficient food for the production of wide rings throughout the tree. But in dry sites or during years of low moisture and high temperatures, food competition within the tree is likely to be greater and the cambium at the base of the stem is likely to receive a limited food supply and may produce narrow rings. The cambium at the stem base depends upon the entire crown for food, hence ring growth reflects the tree's ambient climate. But, the cambium in the top of the tree or in the upper branches depends upon a more restricted portion of the crown for its food and hormone supplies. The rings produced by the cambium vary greatly from branch to branch and are less reliable indicators of the climate surrounding the entire tree than rings at the tree base. Therefore, ring series at the base of trees in semiarid sites provide the most reliable, as well as the longest, record of macroclimatic variation. Tree-ring widths in certain coniferous species growing in semiarid sites appear to represent the integrated effect of climate on food-making and food accumulation in the crown throughout the 14 to 15 months previous to and including the period of growth. Trees in warm, low-elevation sites may utilize winter moisture most efficiently; trees in cool, high-elevation or more northern sites may utilize early summer and early autumn moisture most efficiently. But even with these differences, a significant amount of variance is found to be common among tree-ring series from a wide range of sites, species, and geographical areas in western North America (14, 19, 34), emphasizing a common dependence of ring widths on the gross regional patterns of precipitation and temperature. The remaining variance, which is not correlated among sites, may be attributed to local en-vironmental and climatic differences, to variability among and within trees, and to compounding effects of occasional fires, insect or other infestations, and recurring years of high seed production. It is evident that a large portion of the variability in ring-width patterns from semiarid sites in western North America does reflect differences in climate from year to year. If ring chro- nologies are derived from a number of trees in semiarid sites and if adequate corrections for age and trend are made, these chronologies may be used to reconstruct a first approximation of annual, or somewhat longer period, climatic fluctuations in the past (19).  相似文献   

3.
翁玲  姚正兰  陈宇 《安徽农业科学》2010,38(26):14651-14654
根据赤水市气象站1971~2000年气象资料,对赤水市旅游景区部分景点的气象资料进行订正,分析与人体舒适度有关的气温、水汽压、相对湿度等气象要素的基本气候特征,研究赤水市人体舒适度的分布特征。景区各点地形遮蔽、冬无严寒、夏无酷暑、气候宜人,根据气候指数可知:赤水景区可全年开展旅游业;4~10月是旅游的舒适季节,其中5、6、9月是旅游的最佳季节。赤水景区优异的自然生态环境,景区负氧离子含量高为旅游提供了有利的生态条件。  相似文献   

4.
Flood basalts and hot-spot tracks: plume heads and tails   总被引:4,自引:0,他引:4  
Continental flood basalt eruptions have resulted in sudden and massive accumulations of basaltic lavas in excess of any contemporary volcanic processes. The largest flood basalt events mark the earliest volcanic activity of many major hot spots, which are thought to result from deep mantle plumes. The relative volumes of melt and eruption rates of flood basalts and hot spots as well as their temporal and spatial relations can be explained by a model of mantle plume initiation: Flood basalts represent plume "heads" and hot spots represent continuing magmatism associated with the remaining plume conduit or "tail." Continental rifting is not required, although it commonly follows flood basalt volcanism, and flood basalt provinces may occur as a natural consequence of the initiation of hot-spot activity in ocean basins as well as on continents.  相似文献   

5.
Global change and the ecology of cities   总被引:18,自引:0,他引:18  
Urban areas are hot spots that drive environmental change at multiple scales. Material demands of production and human consumption alter land use and cover, biodiversity, and hydrosystems locally to regionally, and urban waste discharge affects local to global biogeochemical cycles and climate. For urbanites, however, global environmental changes are swamped by dramatic changes in the local environment. Urban ecology integrates natural and social sciences to study these radically altered local environments and their regional and global effects. Cities themselves present both the problems and solutions to sustainability challenges of an increasingly urbanized world.  相似文献   

6.
我国植物物候变化及对气候变化的响应综述   总被引:1,自引:1,他引:1  
丁抗抗  高庆先  李辑 《安徽农业科学》2010,38(14):7414-7417
物候是指示气候变化的主要指标之一,开展物候对全球变化的响应研究是现代物候学研究的一个热点领域。综合论述了现有国内外已有的文献,阐述了研究物候的意义,对比我国北方地区与南方地区的物候变化及其对气候变化的响应,揭示各个区域物候变化趋势及各自特征。  相似文献   

7.
The Composite Infrared Spectrometer observed Jupiter in the thermal infrared during the swing-by of the Cassini spacecraft. Results include the detection of two new stratospheric species, the methyl radical and diacetylene, gaseous species present in the north and south auroral infrared hot spots; determination of the variations with latitude of acetylene and ethane, the latter a tracer of atmospheric motion; observations of unexpected spatial distributions of carbon dioxide and hydrogen cyanide, both considered to be products of comet Shoemaker-Levy 9 impacts; characterization of the morphology of the auroral infrared hot spot acetylene emission; and a new evaluation of the energetics of the northern auroral infrared hot spot.  相似文献   

8.
A theory for the formation of "hot spots" necessary for the initiation of an explosion is discussed in light of experimental evidence that most solid explosives are highly piezoelectric.  相似文献   

9.
Further results from the Venus orbiter radiometric temperature experiment (VORTEX) on the Pioneer orbiter are presented. These are used to characterize the three-dimensional temperature field, the cloud structure, and the dynamics of the 60-to 130-kilometer altitude region of the Venus atmosphere. One of the new discoveries is a "dipole" structure at high latitudes, with two hot spots rotating around the pole, surrounded by banks of cold cloud.  相似文献   

10.
The statistical correlation between the locations of hot spots at the surface of Earth and the distribution of ultra-low-velocity zones at the base of the mantle has about a 1 percent chance of arising randomly. This correlation is more significant than that between hot spots and negative velocity anomalies in tomographic models of deep mantle compressional and shear velocity. This correlation is consistent with the notion that many hot spots originate in a low-velocity, probably partially molten layer at the core-mantle boundary and undergo little lateral deflection on ascent.  相似文献   

11.
Observations of Io in eclipse demonstrate conclusively that Io emits substantial amounts of radiation at 4.8 and 3.8 micrometers and a measurable amount at 2.2 micrometers. Color temperatures derived from the observations fit blackbody emission at 560 K. The required source area to yield the observed 4.8-micrometer flux is approximately 5 x 10(-5) of the disk of Io and is most likely comprised of small hot spots in the vicinity of the volcanoes.  相似文献   

12.
杨淑萍  刘阳  马伟琴 《安徽农业科学》2014,(17):5673-5677,5724
《干旱区资源与环境》自1987年创刊至今已有27年,现已成为国内了解和掌握旱区相关问题研究成果的重要载体。借助数据库提供的文献信息,利用文献计量分析法,透视创刊1987~2013年27年来的发展趋势。基于载文量、研究机构、合作度、合作率、核心作者群、基金论文率、研究热点等指标分析结果表明:27年来,《干旱区资源与环境》栽文量总体呈快速增长趋势,著者研究机构具有明显的地域性,以西北地区为主,尤其集中于内蒙、甘肃和新疆;气候变化、可持续发展、生态环境为该刊出现频次最高的3个关键词,说明期刊研究的重点区域。且分析发现该刊重点研究领域显著,热点研究靶区为新疆、内蒙古、甘肃、黄土高原及干旱区。此外,该刊因核心作者人数不足,核心作者论文产出量过低因而仍末形成稳定的核心作者群。  相似文献   

13.
北京海淀公园被专家戏称为"穿着便衣的皇帝",其设计的成功之处由此可见,但是,笔者通过对公园中部的贯珠泉区的圆形广场北部、东面、正对公园入口处的一块草地群落、公园中心的湖边、公园万泉景区旁边五处景点的分析,发现其也有不足之处,并提出了合理化建议,希望其通过改进,能将海淀公园建设得更加完美,也希望能为其他同类公园的景观设计提供有益借鉴。  相似文献   

14.
The thermal emission from Io's volcanic hot spots is linearly polarized. Infrared measurements at 4.76 micrometers show disk-integrated polarization as large as 1.6 percent. The degree and position angle of linear polarization vary with Io's rotation in a manner characteristic of emission from a small number of hot spots. A model incorporating three hot spots best fits the data. The largest of these hot spots lies to the northeast of Loki Patera, as mapped from Voyager, and the other spot on the trailing hemisphere is near Ra Patera. The hot spot on the leading hemisphere corresponds to no named feature on the Voyager maps. The value determined for the index of refraction of the emitting surface is a lower bound; it is similar to that of terrestrial basalts and is somewhat less than that of sulfur.  相似文献   

15.
青藏高原作为全球气候变化的启动器和调节器,在全球气候变化研究中备受关注。研究全球变暖背景下的青藏高原气候变化以及植被的响应特征,对于推进该区域气候变化研究具有重要意义,目前已有不少该方面的研究报道,但大多局限于对个别气候因素或个别植被响应的描述,缺乏对多种气候因素的综合概括和对植被响应区域差异方面的系统概括。该研究首先总结了青藏高原多个气候参数(气温、降水、积雪、日照辐射、水热通量等)的变化特征;然后归纳了在气候变化背景下,高原植被特征参数(绿度、物候、生产力、碳源/汇)对气候变化响应的规律;最后针对4个环境脆弱区,包括藏北、三江源、环青海湖、林芝,进行了植被变化气候响应特征的讨论。基于以上概述,分析了青藏高原植被气候变化响应研究方面存在的问题,对未来的研究方向进行了展望。  相似文献   

16.
Large-scale nonlinear simulations of Jupiter's 5-micron hot spots produce long-lived coherent structures that cause subsidence in local regions, explaining the low cloudiness and the dryness measured by the Galileo probe inside a hot spot. Like observed hot spots, the simulated coherent structures are equatorially confined, have periodic spacing, propagate west relative to the flow, are generally confined to one hemisphere, and have an anticyclonic gyre on their equatorward side. The southern edge of the simulated hot spots develops vertical shear of up to 70 meters per second in the eastward wind, which can explain the results of the Galileo probe Doppler wind experiment.  相似文献   

17.
The global tectonics of Venus differs significantly from that of Earth, most markedly in that the surface is covered predominately by gently rolling terrain; there apparently are no features like ocean rises; the gravity is positively correlated with topography at all wavelengths; and the few highlands are estimated to be supported or compensated at a depth of approximately 100 kilometers. The surface of Venus appears to be covered mainly by an ancient crust, the high surface temperature making subduction difficult. It seems likely that well over 1 billion years ago water was destabilized at the surface and, soon after, plate tectonics ceased. The highlands appear to be actively supported, presumably as manifestations of long-enduring hot spots.  相似文献   

18.
The Jovian satellite Io has active volcanic hot spots. The point-to-point correlation of the hot-spot distribution indicates that the hot spots preferentially make chains. The arrangement of the chains is periodic with a typical spacing of 120 kilometers. The chains exhibit concordant trends with stresses imposed by the tidal deflection of the lithosphere, suggesting that the hot spots are formed along fissures in the lithosphere. The typical spacing may be controlled by lithosphere thickness.  相似文献   

19.
Excess volcanism and crustal swelling associated with hot spots are generally attributed to thermal plumes upwelling from the mantle. This concept has been tested in the portion of the Mid-Atlantic Ridge between 34 degrees and 45 degrees (Azores hot spot). Peridotite and basalt data indicate that the upper mantle in the hot spot has undergone a high degree of melting relative to the mantle elsewhere in the North Atlantic. However, application of various geothermometers suggests that the temperature of equilibration of peridotites in the mantle was lower, or at least not higher, in the hot spot than elsewhere. The presence of H(2)O-rich metasomatized mantle domains, inferred from peridotite and basalt data, would lower the melting temperature of the hot spot mantle and thereby reconcile its high degree ofmelting with the lack of a mantle temperature anomaly. Thus, some so-called hot spots might be melting anomalies unrelated to abnormally high mantle temperature or thermal plumes.  相似文献   

20.
以江苏省65个县市为研究实证单元,基于区域城乡一体的思想构建乡村性指数,对县域尺度上江苏省乡村性进行定量评价,以ArcGis 9.3、GeoDa 095、SPSS 16等软件平台为支撑,采用Jenks最佳断点分类、空间自相关分析方法,对县域尺度江苏省乡村性的空间分异进行定量地分析与研究。结果表明:县域尺度江苏省乡村性差异性不显著,但乡村性较强区域所占比重略大;从苏南到苏北呈现乡村性梯度递增的空间分异特征;全局上呈乡村性集聚分布态势,局部上在江阴、昆山等7县市和苏北灌云、阜宁等7县形成县域尺度的乡村性"冷点区"与"热点区"。  相似文献   

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