九寨沟林下28种乡土观赏植物种子基本特征     

苏维维  包维楷  周志琼 《山地学报》2010,28(1)

为了筛选九寨沟旅游退化地段林下植被恢复的适宜物种,并揭示乡土植物种子基本性状特征,研究了九寨沟28种观赏性乡土植物种子基本特征 (长宽、种皮厚度、千粒重、活力、萌发率)以及低温层积提高种子发芽能力的作用.调查研究结果是:1) 28种植物种子中4种为小种子(<1 mg),53.6%是中等大小的种子(1～9.9 mg),32.1%为大种子(>9.9 mg).小种子均出现萌发,与小种子相比,种子休眠普遍存在于中等大小和大的种子中.2) 77%的物种种子活力较高(>72%),但仅有7种常规条件下能萌发;窄叶鲜卑花的萌发率最高,达到80%左右,6种植物的萌发率3%～50%.3)低温层积显著提高了蔷薇、毛果铁线莲、宽叶旌节花、假升麻的萌发率(P<0.05),也相对较早地提高了陇东海棠、鲜黄小檗、独活的萌发,但对大多数种子萌发没有促进作用.综合分析表明,九寨沟28种林下或林缘乡土植物中只有窄叶鲜卑花、毛果铁线莲、宽叶旌节花、假升麻、陇东海棠、鲜黄小檗、蔷薇等12种可直播或通过低温层积处理后直播用于旅游干扰退化地段的林下植被恢复中,而其他种类尚需进一步寻求打破休眠的措施和方法.  相似文献   

珊瑚礁生态修复的理论与实践     

覃祯俊  余克服  王英辉 《热带地理》2016,36(1):80-86

南海乃至全球的珊瑚礁生态系统都处于快速退化中,珊瑚礁的生态修复因此成为社会关注的热点内容,但相关理论与技术仍在探索之中。保护珊瑚礁的生态环境、避免对珊瑚礁进一步的破坏无疑是最关键的策略。对于已退化珊瑚礁的修复,初步有以下认识：1）珊瑚移植是重要的技术手段,可通过对移植后的珊瑚进行损伤组织修复、重建免疫系统、改变共生体虫黄藻系群结构等增强移植珊瑚适应新环境的能力。2）园艺式养殖、养殖箱培养等是提供珊瑚移植对象的相对有效途径;人工鱼礁则是协助珊瑚建立发育基底的重要手段;营造和维持适合珊瑚生长的环境有助于提高珊瑚礁生态修复成效。3）可借助水流扩散、幼虫附着和变态行为的化学诱导、微地形对幼虫附着的帮助等可促进珊瑚浮浪幼虫的传播和存活。4）通过杂交等手段改变珊瑚及其共生虫黄藻的基因类型,提升珊瑚对环境的耐受能力和恢复潜力等技术则仍处于实验室试验阶段。  相似文献   

不同补水条件下黄河三角洲湿地恢复情景模拟   总被引：6，自引：1，他引：5  

黄翀  刘高焕  王新功  葛雷  范晓梅  王瑞玲  单凯 《地理研究》2010,29(11):2026-2034

针对黄河三角洲湿地退化现状,设计了三种湿地修复水量预案。利用水文模型SOBEK和地下水模型Visual Modflow对不同补水预案下湿地水文过程进行模拟,将水文模拟结果与湿地立地条件、植被条件在景观决策支持模型LEDESS框架下进行集成,对三种补水预案下湿地修复情景进行模拟和评价。研究表明,对黄河三角洲湿地的恢复,根据区域湿地条件差异,其恢复目标及所需要的适宜水量也有所不同。一千二管理区宜采用最大引水预案,提高涉禽鸟类的生境适宜性;黄河口管理区宜采用最小水量预案,同时应降低生境干扰以改善栖息地质量;对于大汶流管理区,中等水量对于涉禽类和游禽类的生境都有较大改善。本研究将水文过程与景观过程进行集成,利用情景模拟方法,为湿地恢复决策提供一种新的尝试。  相似文献   

Thrust Ramp Geometry and Spurious Rotations of Paleomagnetic Vectors     

Pueyo  E.L.  Pocoví  A.  Parés  J.M.  Millán  H.  Larrasoaña  J.C. 《Studia Geophysica et Geodaetica》2003,47(2):331-357

Interaction of deformation axes during pure translation of a hanging-wall over a footwall composed by frontal and oblique ramps is carefully evaluated together with the evolution of associated paleomagnetic vectors. Four different cases are distinguished on the basis of the deflection on the paleomagnetic vectors when the bedding correction is applied during the restoration process. Two cases (frontal and oblique ramp without mutual interaction) do not produce any deflection. But two cases in the transition zone between both ramps will undergo non-coaxial axis of tilting during progressive deformation. One of them will produce spurious rotation if the bedding correction is applied. These errors will affect the oroclinal bending diagram as well as the fold test producing an apparent oroclinality and an apparent syn-folding magnetization respectively. A well-known geometry and kinematics of the thrust system is needed to properly restore the beds (and vectors) and to avoid the spurious rotations and its collateral effects in paleomagnetic investigations. A paleomagnetic study in the Pyrenean External Sierras is shown as an example. Primary Eocene vectors underwent a clockwise rotation (40° about) during the emplacement of the South Pyrenean sole thrust, however the Rasal-Gabardiella system of oblique ramps display spurious rotations ranging from –8° up to 13° if the inappropriate bedding correction is performed.  相似文献   

STUDY OF THE ECOLOGICAL RESTORATION OF AQUATIC MACROPHYTES IN A EUTROPHIC SHALLOW LAKE     

邱东茹  吴振斌  严国安  李益健  周远捷 《中国海洋湖沼学报》1997,15(1):52-60

mooUonONEutrophicationhasdri,andwillperhapsbethemostwidespreadtypeofenviron-rnentalpollutionofwaterbodis.MostUrbanorsuburbanshallowwaterbodishaveex-perientaladetalrnan-causedeutrophhationinevitablyresultinginovergroWthofphytoplanktonandotherdramaticlakeeresySteInchangessuchasthedeCineofmacrophytes.TheensuingdeteriorationofwaterqualitycaedseriousenvirorunentalanderenoAncprobbo,bousemostoftheselakes,asidefrombeingwatefbodiesforlargescalecoInmendalfisheryusuallysupplywaterforindustryandagrict…  相似文献   

Application of forecasting structural cracks technique of 3DMove in Chengdao buried hill     

WU Shiguo    WANG Xiuling  JI Yuxin  LIU Yuzhen & HAN Wengong . Institute of Oceanology  Chinese Academy of Sciences  Qingdao  China  . Geophysical Research Institute  Shengli Oil Field  Dongying  China 《中国科学D辑(英文版)》2005,48(9):1403-1410

Crack reservoir beds have large proportion in China. With the development of exploration in basins, the ratio of the crack reservoir beds will grow year after year. There have been 15 crack buried hill reservoirs since the first wellbore was successfully drilled in carbonate rock and Zhengjia granite in the Zhuangxi area in the 1980s[1]. Also mudstone-crack reservoirs and compact low-penetrability reservoirs have been discovered. With the development of exploration and exploitation in oil fi…  相似文献   

The recent sedimentation history of Aqualate Mere (central England): assessing the potential for lake restoration   总被引：1，自引：0，他引：1  

Simon?M.?HutchinsonEmail author 《Journal of Paleolimnology》2005,33(2):205-228

As part of English Natures Lakes Flagship Project to address adverse environmental impacts on selected, important lakes, a proposal has been made to dredge Aqualate Mere. The site has experienced rapid, recent sedimentation thought to be derived from a nearby canal. The aim of this study has been to determine the recent sedimentation history of the site in order to assess the possibility of the disposal to land of its sediments and the efficacy of this form of lake restoration. A predominantly clayey silt layer was found across the lake beneath which darker, organic-rich sediments were noted. This transition may represent the input of canal-derived sediments, although it may reflect other environmental changes at this time. The radiometric dating technique employed was unable to date this sediment boundary. A further change in the characteristics of the upper part of the clayey silt layer may represent an additional influence of the canal. Heavy metal levels were modest, whereas nutrient levels were relatively high and some pesticides were detected. Topsoil erosion supplying nutrients and other compounds associated with agriculture have been an important source of the lower layers of the clayey silt sediments in particular. The highest levels of most pollutants were found in the finer sediments in the uppermost (post-1950s) part of the sediment profile. These sediments appear to reflect a change in the characteristics of the sediments of the canal, which was associated with a change in the nature of its water supply. The key geochemical properties of the sediments should not preclude the land-based disposal of dredged materials under current UK regulations for waste management. Accurate estimation of sediment quantities was limited, as the interface between the recent and underlying sediments was not positively identified at all sample points.  相似文献   

A Multiscale Vision Model to Analyse Field Astronomical Images     

Frédéric Rué  Albert Bijaoui 《Experimental Astronomy》1997,7(3):129-160

We have implemented a multiscale vision model based on the wavelet transform to analyse field astronomical images. The discrete transform is performed by the à trous algorithm. The vision model is based on the notion of significant structures. We identify the pixels of the associated wavelet transform space (WTS) with the objects. For each scale a region labelling is carried out. An interscale connectivity graph is then established. In accordance with some rules that permit false detections to be removed, the objects and their sub-objects are identified. They define respectively trees and sub-trees in the graph. In this way, the identification of the WTS pixels of the tree related to a given object leads to the reconstruction of its image by the conjugate gradient method. The model has been tested successfully on simulated images of stars and galaxies which allow us to show the capabilities of the detection and restoration procedures of the model. Finally, tests on real images show that one can analyse complex structures better than with classical astronomical vision models.  相似文献   

THE USE OF A CROSS-CORRELATION TECHNIQUE TO ENHANCE JANSSON''S DECONVOLUTION PROCEDURE     

PAUL BENJAMIN CRILLY 《地理学报(英文版)》1990,(4)

The use of a cross-correlation prefiltering technique to enhance the ability of Jansson's iterativedeconvolution procedure to deconvolve extremely noisy chromatographic data is investigated.Test casesinclude peaks whose resolutions are as low as 0.35 and whose signal-to-noise ratios are as low as 1:1.Evaluation criteria include RMS error,relative peak error and peak area repeatability.For comparisonpurposes,relative peak area errors and peak area variances are also evaluated for noisy but well resolvedpeaks that have only been prefiltered with the cross-correlation filter.Jansson's method in conjunctionwith cross-correlation prefiltering is shown not only to resolve overlapped peaks but in some cases toimprove their signal-to-noise ratios.The study also establishes some limits to the capabilities of Jansson'smethod will regard to adverse data conditions.  相似文献   

P-immobilisation and phosphatase activities in lake sediment following treatment with nitrate and iron   总被引：3，自引：0，他引：3  

Gerlinde Wauer  Thomas Gonsiorczyk  Peter Casper  Rainer Koschel 《Limnologica》2005,35(1-2):102-108

The influence of a further developed inlake restoration method on the P-immobilisation and microbial activities, especially under anoxic conditions was investigated. The impact of nitrate and iron dosing with a newly developed nitrate storage compound (Depox^®Fe) was tested in enclosures in the eutrophic dimictic Lake Dagowsee, Germany. Additions of 50 g m⁻² of NO₃⁻–N and 66 g m⁻² of Fe³⁺ ensured availability of nitrate at the sediment surface during a 2-months period.As a result the phosphate release from the anoxic sediments was completely suppressed even 1 year after the application. The hypolimnetic deoxygenation was unaffected by the Depox^®Fe addition. However, sulfur reduction and methanogenesis were inhibited and the phosphatase activity increased.  相似文献