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991.
992.
An exploratory survey was conducted on the uses and role of invasive alien species(IAS) to local livelihoods in the Rema-Kalenga Wildlife Sanctuary in the northeastern hilly region of Bangladesh.Vegetation was sampled in 50 quadrates,each 10 m×10 m,and 25 line transects,each 50 m×20 m,through a combination of random and systematic sampling.Group discussions were also arranged with fifty local inhabitants(17 % of the total inhabitants) to learn the various uses of IAS.A total of 17 alien plant species belonging to 10 different families,of which Leguminosae constitutes the highest number(5 species),include tree(53%) followed by herb(12%),shrub(12%) and others(weed,climber and palm).The majority of the identified species were found to be used for fuel,followed by timber production,medicinal or curative uses,fodder,and many others.In addition to providing various forest products,alien tree species planted in forest plantation help provide many vital ecosystem services such as soil amelioration through nitrogen fixation.It is true that the alien species have some negative impacts on local ecosystems,and not all of them are harmful.Therefore,a national programme must be initiated to distinguish the harmful from the harmless species and to identify the uses and impacts of the former and latter. 相似文献
993.
The concept of functional ecogeomorphology developed originally from the study of fluvial systems represents an insightful framework for describing landforms as structures adjusting to external physical forces, and also as functional components contributing to the complex play of interactions and reciprocal adjustments between biotic and abiotic elements of ecosystems. In this commentary we propose to extend the model of functional ecogeomorphology by classifying landforms in three fundamental components: abiotic, residual and functional. The various possible combinations of these three components are presented and discussed in the scope of evolutionary geomorphology. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
994.
The impact of sewage and stormwater effluents on phytoplankton is investigated by comparing organic-walled dinoflagellate cyst abundance and diversity from 38 surface sediment samples, flanking southern Vancouver Island. Site locations include those directly adjacent to wastewater outfall at Clover and Macaulay Points and Saanich Peninsula, as well as from a variety of near-shore environments with differing tidal flow influences. Excellently preserved dinoflagellate cyst assemblages have been recovered and 36 cyst taxa were identified. Local assemblages are characterized by a high relative proportion (average 56%) of cysts produced by heterotrophic dinoflagellates, which is typical for regions of high primary production. Relative proportional increases of cysts from heterotrophic species with particular increases of Polykrikos kofoidii/schwartzii and Dubridinium species, known to reflect areas affected by eutrophication, occur directly adjacent to all three sewage outfalls, as well as in the more stagnant waters of Esquimalt and Victoria Harbours and at the mouth of Cadboro Bay. Further effects of an anthropogenic effluent can be seen in the relatively higher concentrations of organic carbon and the diatom production proxy, biogenic opal. Results from this study clearly indicate a much larger impact zone than predicted by a sewage effluent plume model or trends found in monitored benthic biota and sediment chemistry that evidence primary outfall affects <800 m eastward of Macaulay Point and about 200 m eastward of the Clover Point. Enhanced production of cysts from potentially toxic Alexandrium species is also observed near locations of sewage outfalls. 相似文献
995.
植物激素是一类由植物合成的痕量有机物质,调控着植物的生长发育及对环境的适应。藻类属低级植物类群,且具有与高等植物类似的大多数激素类型,相对而言,藻类激素含量更少,却发挥着更高效的生理活性。无论在藻类,还是高等陆地植物,胁迫响应一直是研究十分活跃的领域。其中脱落酸(ABA)作为应激激素,所起的调节作用已得到人们的共识。本文总结了近些年关于ABA在藻类中的分布,ABA对抗氧化酶系的调控,ABA信号传导路径在陆地植物中的发现与代谢机制,以及利用蛋白质分子系统学对ABA信号传导途径的起源与进化的分析。在此基础上,提出未来藻类ABA参与的抗逆代谢调控研究应着重从潮间带海藻出发,参考陆地植物研究的成果,应用生物信息学结合生物化学等的手段,进行相关机制的探索。 相似文献
996.
科尔沁沙地松树山地区苔藓植物物种多样性与分布特征分析 总被引:2,自引:2,他引:0
通过标本采集和群落调查,探明科尔沁沙地松树山地区有苔藓植物76种(包括变种和亚种),可归为苔类(9种)和藓类(67种)两个大的类群,隶属于21科、41属;可划分为7种区系地理成分,以北温带成分、世界广布种和东亚成分为主要区系成分, 分别有48种、12种和8种。石缝土层、岩面、树干小生境苔藓植物群落丰富,少数物种局限分布在一种小生境中,多数物种同时分布在两种以上小生境中。维管植物群落共有地面生苔藓植物39种,优势种有双色真藓(Bryum dichotomum)、土生对齿藓(Didymodon vinealis)、小疣冠苔(Mannia triandra)、西伯利亚疣冠苔(Mannia sibirica)、褶叶青藓(Brachythecium salebrosum)。随着水分条件改善,地面苔藓植物群落优势种构成发生有规律地变化,顶蒴藓类→顶蒴藓类+叶状体苔类→叶状体苔类+顶蒴藓类→侧蒴藓类+叶状体苔类+顶蒴藓类。认识群落随水分条件变化的特征对从更大尺度上认识苔藓植物结皮层形成和维持有重要参考价值。 相似文献
997.
Beach–dune sediment budgets and dune morphodynamics following coastal dune restoration,Wickaninnish Dunes,Canada
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The results from three years of surveying and monitoring a dynamic foredune and dunefield restoration effort on Vancouver Island, Canada is presented. Complete removal of foredune vegetation occurred in three phases spaced a year apart in an effort to control invasive Ammophila spp. The collection of airborne LiDAR, orthophotographs, and bi‐monthly topographic surveys provided a means to quantify and examine sediment budgets and geomorphic responses. Three survey swaths, corresponding with each phase of vegetation removal, were established to provide detailed topographic coverage over the impacted beach, foredune, and dunefield landscape units. The swath corresponding with the first phase of removal recorded a positive sediment budget of 1·3 m3 m?2 after three years. A control swath, with data collected for a year prior and two years following removal, exhibited a distinct pulse of sediment delivery into the dunefield unit with a maximum gain of 0·03 m3 m?2 pre‐removal compared to 0·11 m3 m?2 post‐removal. Vegetation analysis zones, associated with each of the three swaths, demonstrate a range of vegetation responses due to variation in the vegetation removal and subsequent re‐invasion or removal methods employed. The first site to be cleared of vegetation, received ongoing invasive re‐growth control, and three years following removal vegetation cover dropped from 57% in 2009 to 13% in 2012 (?44%). An adjacent site was cleared of vegetation two years later (only one year of recovery) but experienced rapid Ammophila re‐invasion and percent cover changed from 61% in 2009 to 26% in 2012 (?35%). The data presented provides insights for improving the application of sediment budget monitoring in dynamic restorations and discusses the potential for detailed spatial–temporal survey data to improve our understanding of meso‐scale landscape morphodynamics following foredune disturbance. Overall, the vegetation removal treatments reduced the extent of invasive grass and increased dunefield mobility and dynamic activity. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
998.
TANG Yijie FANG Zhanqiang CHEN Kang ZHANG Zaiwang ZHONG Yanting AN Dong YANG Xiongbang LIAO Baowen 《海洋学报(英文版)》2012,31(5):115-125
The study aims to compare the differences of macrofauna communities of wetlands at 3-year-forest- age, 5-year-forest-age Sonneratia apetala artificial mangroves, 5-year-forest-age Kandelia candel ar- tificial mangroves with the same restoration background, and the naked tidal flat in the Qi’ao Island Mangrove Nature Reserve of Zhuhai, Guangdong Province. The results show that there were signif- icant structural differences in macrofauna communities among four kinds of habitats. The increase of biomass and species diversity of macrofauna at 3-year-forest-age S. apetala artificial mangroves was obviously faster than that at 5-year-forest-age K. candel artificial mangroves whose average tree height was close to that of 3-year-forest-age S. apetala artificial mangroves. The BIOENV analysis shows that it was related to the rapid growth of S. apetala, which rapidly changed the light level and shading conditions in the forests. The 5-year-forest-age S. apetala artificial mangroves had lower macrofauna species diversity but higher density and biomass than K. candel artificial mangroves with the same forest age. This was due to the rapid changes of physical and chemical properties of habitat soil by the ecological restoration of S. apetala artificial mangroves as well as the changed food sources possibly caused by the leaf-litter of such non-indigenous mangrove species S. apetala. However, further survey should be conducted on whether there are any negative ecological impacts of large-scale cultivation of S. apetala on macrofauna communities, so as to evaluate correctly S. apetala’s role in the restoration of coastal mangrove ecosystems. 相似文献
999.
Luca Garibaldi 《Marine Policy》2012,36(3):760-768
With data series extending for 60 years, including catch data for almost 1850 species items, and reflecting geo-political, historical and natural events, the FAO capture database provides a service to the community interested in fishery information. Over 600 articles from refereed journals cited the database in the last 15 years. Species included grew significantly in the last decade and an analysis of annual reporting showed more timely data submissions, although the number of non-reporting countries remained stable throughout the years. An evaluation of data quality found over half developing countries reporting inadequately but also one-fourth of reports by developed countries were not satisfactory. This article also provides meta information on historical developments, data sources and coverage, and advice on what should be kept in mind when using the database for trend studies. 相似文献
1000.
2009-08对乐清湾进行了生物调查。共鉴定浮游动物66种,浮游幼虫15类,分为半咸水河口类群、近海暖温带类群、近海暖水类群和大洋广布类群,其中近海暖水类群占主导地位。Ⅰ型网主要优势种有针刺拟哲水蚤、汤氏长足水蚤、太平洋纺锤水蚤、刺尾纺锤水蚤等;Ⅱ型网主要优势种有针刺拟哲水蚤、强额拟哲水蚤、太平洋纺锤水蚤、刺尾纺锤水蚤、短角长腹剑水蚤、简长腹剑水蚤、小长腹剑水蚤等。浮游动物优势种分布有明显差别,太平洋纺锤水蚤分布仅限于湾顶海区,小长腹剑水蚤密集区也在此区域,其它优势种则分布于乐清湾中部和湾口海区。浮游动物平均生物量为125.05mg/m3,平均丰度为234.00个/m3,数量分布呈现出从湾顶向湾口逐渐降低的趋势。 相似文献