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荔波小七孔岩溶植被的研究 总被引:2,自引:2,他引:0
通过实地调查、样方统计、标本采集等,对荔波小七孔地区岩溶植被的生境条件、区系组成、群落学特征等进行了初步的分析研究.结果表明:该区植被区系十分丰富,在12km2的范围内,自然分布的维管束植物高达375种,分别隶属于117科、272属;地理成分也相当复杂,既有世界分布、泛热带分布、热带美洲和热带亚洲间断分布、热带亚洲至热带非洲分布,又有北温带分布、东亚和北美间断分布、西亚至中亚分布和中国特有分布.此外,区内岩溶植被多元顶极演替特征也很明显,常绿阔叶、落叶阔叶与常绿落叶阔叶混交林共存.小七孔的这种植被群落特征主要由其气候、土壤、小生境差异及其相互配置的不同而引起. 相似文献
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鄂西南岩溶地区表层岩溶带发育强度变化规律研究 总被引:5,自引:5,他引:0
鄂西南岩溶地区表层岩溶个体形态复杂多样,表层岩溶带发育与鄂西南地区岩溶地质环境条件及岩溶发育演变的历史过程密切相关.因此,通过野外地质调查与收集"沪蓉西"高速公路勘察资料.采用系统工程地质分析为主的方法,研究了表层岩溶带在不同的地质构造部位、地层岩性、地形地貌部位及深部岩溶水补径排区的发育强度及其变化规律.详细论述了表层岩溶带的空间发育强度.首次定量界定了该区表层岩溶带的最大发育深度为56.54m,最浅为4.5m,阐明了表层岩溶带从山顶、山脊到山脚、沟谷由弱到强的总体变化规律. 相似文献
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西南岩溶地区是我国主要岩溶带之一,也是世界岩溶研究重点地区,区内因人口众多,植被破坏严重,部分地区因人为作用已经产生一系列的环境问题,本文从岩溶地区植被演替规律出发,针对不同植被生态条件,通过对比不同表层岩溶泉的水化学特征和表层土壤空气CO2(g)(表示呀以气相形式存在)的含量,分析了植被在岩溶区,特别在表层岩溶带的喀斯特效应,由此,一方面可以推动岩溶研究的进一步发展;另一方面可以提高人们的岩溶环境保护意识,从而为西南地区生态恢复提供基础资料。 相似文献
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岩溶石漠化遥感信息增强技术探讨 总被引:6,自引:0,他引:6
岩溶石漠化是存在于中国西南及南方岩溶地区严重的脆弱生态地质问题,利用遥感技术的优势,可以准确、快速、经济地获取岩溶石漠化的现状、分布规律等结果数据,为石漠化的监测、石漠化的演变分析及后续治理提供科学依据。但在遥感调查与监测工作中,如何增强石漠化信息,方便后续的信息提取工作,已成为研究的热点与难点问题。影响岩溶石漠化的发育的因素众多,其评价指标一般考虑岩石裸露程度及其结构、植被结构等。在岩溶石漠化遥感信息增强工作中,很难直接获取岩石的裸露信息。野外调查发现:在热带亚热带岩溶地区,岩石的裸露程度与植被覆盖程度呈负相关关系,岩石的裸露程度越高,植被覆盖程度越低,岩溶石漠化越发育;据此可以利用植被覆盖情况来获取岩溶石漠化信息。在增强岩溶石漠化信息方面,本文提出了改进增强型植被指数模型(GEVI),并与现有的常用植被指数模型对比试验发现,具有较好的应用效果。 相似文献
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万华岩表层岩溶带岩溶动力系统的特点研究 总被引:3,自引:1,他引:2
万华岩地区碳酸盐岩中普遍发育的非碳酸盐岩夹层,以及“土层+裂隙层”表层岩溶带双层结构对岩溶动力系统和水循环具有显著影响:非碳酸盐岩地段的地下水因其矿化度较低,CO2 含量较高,而具有较强的侵蚀、溶蚀能力,导致岩溶动力系统的物质和能量传输非常活跃,一个岩溶泉年溶蚀量(以CaCO3计)达2795.4kg;由于非碳酸盐岩夹层的普遍存在,不仅阻碍地下水向深循环,而且还有利于土壤、植被的发育。土壤、植被与地表岩溶裂隙网络对区内岩溶地下水还具有较好的调蓄作用,以致使区内有众多的小泉点在地表出露。 相似文献
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贵州茂兰喀斯特森林植被演替序列的数量分析 总被引:4,自引:1,他引:3
综合运用双向指示种分析法( TWINSPAN)及除趋势对应分析法( DCA)进行分类及排序,确定了贵州茂兰国家级自然保护区森林群落的演替序列。结果表明: 根据DCA排序可将研究区植被群落的演替过程分为四个阶段,即草地→ 灌丛→乔林→顶极群落;根据TW IN SPAN分类结果可将植被分为11个群丛,其中,第Ⅰ 、Ⅱ 、Ⅲ 、Ⅳ 群丛为草本阶段,第Ⅴ 、Ⅵ 群丛为灌丛阶段,Ⅶ 、Ⅷ 、Ⅸ 群丛为乔林阶段,第Ⅹ 、Ⅺ群丛为顶极阶段。茂兰喀斯特植被演替顶极群落为亚热带常绿落叶阔叶林群落,是一种典型的地形— 土壤演替顶极,是植被与当地环境长期适应的结果。 相似文献
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Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco. 相似文献
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The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts 总被引:4,自引:0,他引:4
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species. 相似文献
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Muriel Rocher Stéphane Baize Stéphane Jaillet Edward Marc Cushing Yannick Lozach Francis Lemeille 《Comptes Rendus Geoscience》2003,335(8):701-708
Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ1 roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003). 相似文献
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正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level 相似文献
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正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7), 相似文献
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正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci- 相似文献
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正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli- 相似文献
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正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.) 相似文献
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正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861 相似文献