江汉湖沼资源的开发与保护

湖沼是重要的自然资源,是开发水体生态农业以及发展轻化工业原材料的生产基地保护湖沼资源不但能调控环境,且可成为天然水生或沼生生物基因库。对江汉湖沼资源的合理开发利用,既能收到巨大经济效益,又可保护湖沼生态环境和发挥其生态效益作用。     

农作物品种单一化的影响

绿色革命是人与自然关系的产物--集约型农业与高产农业的一大壮举.但绿色革命带来的负面影响也是巨大的,主要是农作物品种单一化引起的农业种质资源的减少和农业生态系统的脆弱.本文就绿色革命的这一负面影响进行阐述并提出对策.     

Canopy Seed Banks as Time Capsules of Biodiversity in Pasture-Remnant Tree Crowns

Abstract: Tropical pastures present multiple barriers to tree regeneration and restoration. Relict trees serve as “regeneration foci” because they ameliorate the soil microclimate and serve as safe spots for dispersers. Here, we describe another mechanism by which remnant trees may facilitate pasture regeneration: the presence of seed banks in the canopy soil that accumulates from decomposing epiphytes within the crowns of mature remnant trees in tropical cloud forest pastures. We compared seed banks of canopy soils (histosols derived from fallen leaves, fruits, flower, and twigs of host trees and epiphytes, dead bryophytes, bark, detritus, dead animals, and microorganisms, and dust that accumulate on trunks and the upper surfaces of large branches) in pastures, canopy soils in primary forest trees, and soil on the forest floor in Monteverde, Costa Rica. There were 5211 epiphytic and terrestrial plant seeds in the three habitats. All habitats were dominated by seeds in a relatively small number of plant families, most of which were primarily woody, animal pollinated, and animal dispersed. The density of seeds on the forest floor was greater than seed density in either pasture‐canopy or forest‐canopy soils; the latter two did not differ. Eight species in 44 families and 61 genera from all of the habitats were tallied. There were 37 species in the pasture‐canopy soil, 33 in the forest‐canopy soil, and 57 on the forest floor. Eleven species were common to all habitats. The mean species richness in the pasture canopy was significantly higher than the forest canopy (F =83.38; p < 0.02). Nonmetric multidimensional scaling ordination revealed that the communities were distinct. Greenhouse experiments verified that many of these seeds were viable, with 29 taxa germinating (23 taxa in pruned mats [mimic of exposed conditions] and 16 taxa in control mats [intact conditions]) within 2 months of observation. Nearly half the species that germinated were characteristic of primary forests (primary forest samples, 19%; pasture samples, 29%). This supports the idea that canopy seed banks of pasture trees can function as time capsules by providing propagules that are removed in both space and time from the primary forest. Their presence may enhance the ability of pastures to regenerate more quickly, reinforcing the importance of trees in agricultural settings.     

Control of upland bank erosion through tidal marsh construction on restored shores: Application in the maryland portion of Chesapeake Bay

During the period of 1972 through 1993, Environmental Concern Inc. (EC) and its recent (1989) affiliate Environmental Construction Company (ECC) have completed 216 marsh construction projects to control upland bank erosion in tributaries of the Maryland portion of Chesapeake Bay. Of these projects, 26 have involved marsh construction on unaltered existing shores and 190 have utilized marsh construction on shores that have been restored to former increased elevations through shoreline filling and grading. This paper describes the latter restoration technique. Throughout the 21-year period of applying the technique for long-term upland bank erosion control, refinements to the design standards and criteria for site suitability have been made so as to optimize its successful application. As a result of this experience, a reliable bioengineering restoration technique has evolved to control upland bank erosion. This paper describes the details of this successful technique through a review of: (1) its objectives and benefits, (2) suitability of sites for its application, (3) the design of its shore restoration, (4) its construction, (5) its maintenance, and (6) comparison of its cost with those of structural techniques for bank erosion control. Although the technique has only been applied in the Maryland portions of Chesapeake Bay, its applicability should, with modifications, be broadly applicable to all water bodies.     

淮南市防震减灾决策系统的建立

在机制上将一个地市(淮南市)的地震预报与防震决策融为一个动态整体,从而建立起一个实用性强的防震减灾决策系统,使城市各种防震对策的生成有了更科学的基础。成为市政府在防震减灾决策中不可缺少的工具。     

汉江蜀河水电站库水位对岸坡稳定性的影响分析

汉江蜀河水电站属于Ⅱ等大(2)型水电站,水库的建成、运行可能对岸坡的稳定性造成一定的影响,尤其是水库蓄水后的库水位变化及与库水位变化相关的参数,对岸坡的稳定影响极大,因此弄清楚库水位变化与其相关的参数对岸坡稳定性的影响,是汉江蜀河水电站成功运营必须解决的问题之一。以地质背景为基础,结合具体坡段的岩性、结构特征等,从水库水位公式的建立,到在不同库水位的条件下,运用数值模拟对岸坡稳定性系数和相关参数的变化进行了分析评价。     

EROSIONAL POTENTIAL OF STREAMS IN URBANIZING AREAS1

ABSTRACT: In urbanizing areas, the usual increase in flood flows also increases erosional capability of streams. In order to evaluate such tendencies quantitatively, 25 stream reaches were studied, and were classified as to whether erosion of the channel and banks was light, medium, or heavy. Analysis of characteristics indicated that (1) densely developed areas are correlated with greater erosion, (2) wide stream buffers of natural vegetation are correlated with lesser erosion, and (3) there is no definite correlation of erosion to slope or characteristics of soil. Erosional stream instability can be avoided by retention of storm water runoff, creating additional channel roughness or reducing channel slope during floods by drop structures, such as culverts, which restrict flow. Channel straightening and general bank protection should be minimized in such streams. Design of culverts should take such effects into consideration.     

降雨主导型库岸滑坡变形时空分布特征

根据某大型水库近坝库岸滑坡8年的监测资料,对该滑坡变形的时空分布特征进行了分析。该滑坡变形的空间分布特征主要表现为3个方面的差异,即区域差异、高程差异和深度差异。而滑坡变形的时间分布特征主要体现在库水作用和降雨两个方面:在重点监测的Ⅱ区,库水作用只影响到其前端部分,对中、后部影响很小;该区的整体变形与降雨关系密切,响应明显。这些特征表明该滑坡为降雨主导型库岸滑坡,并有向稳定方向发展的趋势;但Ⅱ区特有的"后坐式"变形特征又存在一定的安全隐患,因此,该滑坡的监测还应长期进行。     

河流岸坡净化径流中氨氮的实验室研究

利用实验室内建立的河流岸坡展开对地表径流中氨氮在模型内部沿程净化效果的实验研究。结果显示,河流岸坡对氨氮的去除率在90%以上;沿程氨氮浓度在缓坡模型的第二断面、第三断面的浓度及净化效率较为稳定,而在陡坡模型中的第三断面浓度及净化效率均出现较大波动;此外,合理的进水负荷使两种河流岸坡对氨氮的去除率稳定在96%左右;相比较而言,缓坡模型沿程对氨氮的净化效率要比陡坡模型稳定。     

长江中下游河道与岸线演变特点

分析了长江中下游河道岸线变化的主要因素，它们分别是河岸崩塌，泥沙淤积及人类活动等，其中河岸崩塌是河道岸线演变的最主要原因。总的来说长江中下游干流河势是稳定的，但五个河段有各自演变特点和规律，其中宜昌－枝城段河道与河床比较稳定，岸线顺直，但葛洲坝和三峡水利枢纽建成后对河床的冲刷作用较大；荆江段是长江著名的河曲段，其冲淤变化较大；城陵矶至湖口段为节点和分汊河床组成，一般来说节点较为稳定，而分汊河床不太稳定，湖口至江阴河段岸线一般较为稳定，但弯道河床变化较大；河口段不但受江流作用影响，还受潮流与波浪等共同影响，所以河口河床演变迅速，主要表现为汊道主泓迁移摆动。