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UCXP-wa相机影像分辨率较高,已经成为国内航空摄影测量的主流设备。本文结合吉林某测区任务,介绍了利用UCXP-wa相机影像数据快速制作正射影像的技术流程,并结合实际工作,对作业中经常出现的问题进行分析,探讨了提高正射影像质量和效率的方法及技巧。 相似文献
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稀土元素因其丰富的光、电、磁、热特性被广泛应用于传统工业领域及新兴产业领域,稀土资源被多数国家认定为是战略性资源或关键性矿产资源。我国是稀土资源大国,无论从储量、产量还是消费量上来看我国都居于世界前列。从资源管理角度我国稀土资源战略定位可以概括为有效保护和合理利用稀土资源,保障资源供应安全;坚持国家利益最大化,优先满足国内应用需求;节约集约利用资源,在开发利用的同时保护生态环境。本文初步探讨了以计划为基础和以市场为导向的两种实现稀土资源战略的实施路径,并就此提出稀土产业发展的相关建议 相似文献
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鱼类是水禽栖息地及其迁徙停歇地中的重要食物基础。吉林莫莫格国家级自然保护区是白鹤(Grus leucogeranus)和东方白鹳(Ciconia boyciana)等珍稀濒危鸟类迁徙的重要停歇地。针对该保护区中的鱼类资源增殖能力下降、水禽栖息地及其迁徙停歇地的适宜性水平降低的现状,2016年至2017年期间,采用湿地水文和基底修复的方法,对嫩江近岸浅水区和洪泛区中鱼类的自然栖息地进行了修复;鱼类栖息地修复前、后,分别于2015年9月和2017年11月至2021年9月期间,在鱼类栖息地,开展了鱼类样本采集和调查,研究了鱼类栖息地修复前、后鱼类群落的组成和结构特征,评价了鱼类栖息地的修复效果。研究结果表明,与鱼类自然栖息地相比,修复栖息地的鱼类物种数量明显增多,而经济鱼类的相对种群生物量和相对种群数量却分别减小了16.02%和39.98%,小型非经济鱼类的相对种群生物量和相对种群数量比自然栖息地分别增大了1.43倍和63.54%,鱼类现存资源量、平均年鱼类现存资源量和平均年鱼类分布密度大幅增加;修复栖息地鱼类群落的Simpson多样性指数和Pielou均匀度指数比自然栖息地分别减小了31.... 相似文献
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大型底栖动物群落在河流生态系统中发挥着重要作用,2003年6月至2004年6月间对汉江流域2级河流——黑竹冲河大型底栖动物优势种类的生活史和生产力进行为期一周年的研究．结果表明：主要优势种圆顶华溪蟹（Sinopotamon teritisum Dai et al．）生活史周期基本为四年,每年8—10月为主要繁殖季节,衰老个体（体宽〉29mm）在每年的1—2月份死亡较多;现存量在一周年中变化较大,密度9月份达到峰值,为35ind／m^2,生物量在6月达到峰值,为41．7g／m^2;采用体长频率分布法（size—frequency method）测算的周年生产量为151,3071g／（m^2．a）,P／B系数为1．4．在其胃内含物中,无形态碎屑占45．4％,虾占10．9％、水生昆虫占35．6％、螺占5．7％、植物组织占8．1％,对次级生产量的贡献率分别10.84％、18．21％、59．49％、9．52％和1．94％． 相似文献
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汉江流域黑竹冲河五种优势摇蚊的周年生产量及营养基础分析 总被引：3，自引：0，他引：3
2003年6月至2004年6月间对汉江流域2级河流——黑竹冲河大型底栖动物群落优势种类的生产力进行为期一周年的调查研究,其中主要优势摇蚊中粗腹摇蚊(Pentaneura sp．)和多足摇蚊(Polypedilum sp.)的生活史为一年三代, 小摇蚊(Microtendipes sp．)和帕摇蚊(Pagastia sp．)为一年两代,刺突摇蚊(Chaetocladius sp．)为一年一代．粗腹摇蚊种群生物量和多度在一年中出现两次峰值,多足摇蚊则出现三次,小摇蚊在6月份达到最大峰值,刺突摇蚊在1月份达到最大峰值,帕摇蚊在10月份和次年1月份分别达到次峰值和主峰值．采用龄期频率法(instar-frequency method)测算的周年生产量(鲜重)分别为:粗腹摇蚊,19．9233g/(m2·a),P/B为8．7;多足摇蚊,7．2177g/(m2·a),P/B为8．1;小摇蚊, 0．8996g/(m2·a),P/B为6．0;刺突摇蚊,3．2533 g／(m2·a),P／B为3．4;帕摇蚊,8．5132g/(m2·a),P／B为8．4．除粗腹摇蚊外,其它四种摇蚊的前肠内含物中无形态碎屑所占比例均高于90％,对生产量的贡献率达到77％-96％;粗腹摇蚊的动物性食物所占比例达到14．73％,其对生产量的贡献率高达46．04％． 相似文献
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The production dynamics and trophic basis of 7 dominant species of chironomids were investigated in the area of a second-order river of the Hanjiang River basin, in central China from June 2003 to June 2004. The results showed that Tvetenia discoloripes was by far the most abundant chironomid, dominating the overall standing stock of the taxa. In terms of life cycle, Chaetocladius sp., Eukiefferiella potthasti and T. discoloripes developed 1 generation a year, whereas Microtendipes sp. and Pagastia sp. developed two, while Pentaneura sp. and Polypedilum sp. developed three. T. discoloripes was the most productive chironomid with 120.305 8 g/m2.a, Pentaneura sp. and E. potthasti had relatively high production values of >17 g/m2.a, and the rest were <10 g/m2.a. All the production temporal variation tended to follow biomass patterns. T. discoloripes, Chaetocladius sp. and Pagastia sp. concentrated most of their production in winter, whereas E. potthasti, Pentaneura sp. and Polypedilum sp. had relatively higher production throughout the year. Only Microtendipes sp. had a production that peaked in summer. The overlap in temporal distribution of production among the chironomid species was generally high (>0.5), especially for filter-collectors Microtendipes sp., Chaetocladius sp., Chaetocladius sp., T. discoloripes and Pagastia sp. All species except Pentaneura sp. consumed a large portion of amorphous detritus, constituting more than 90% of their diets, and contributing nearly 90% to their secondary production. All the 7 chironomids represent obvious adaptation to local highly variable climate in summer and autumn in life cycle pattern, production dynamics, and food type. 相似文献
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From June 2003 to June 2004, an investigation on the life cycle, production and trophic basis of dominant species of macrozoobenthos community in a second-order river of the Hanjiang River basin, Hubei, China was carded out. The results showed that the dominant species Leptophlebia sp. and Ephemera sp. appeared to develop two generations per year, and there was a small overlap in the two generations of both species. The pupation of Leptophlebia sp. mainly occurred in autumn and winter, while pupation of Ephemera sp. mainly took place in summer and winter. The standing stocks of the Leptophlebia sp. population and Ephemera sp. population had two peaks in a year. The cohort production and cohort P/B ratio of the Leptophlebia sp. population estimated by size frequency method were 19.018 1 g/m^2.a and 5.7 respectively, while its annual production and P/B ratio were 38.036 2 g/m^2.a and 11.4. The cohort production and cohort P/B ratio of the Ephemera sp. population were 38.015 9 g/m^2.a and 5.9, while its annual production and P/B ratio were 76.031 8 g/m^2.a and 11.8. 相似文献
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