Wetland effects on lake water quality in the Minneapolis/St. Paul metropolitan area     

Naomi E. Detenbeck  Carol A. Johnston  Gerald J. Niemi 《Landscape Ecology》1993,8(1):39-61

A method developed to evaluate the cumulative effect of wetland mosaics on water quality was applied to 33 lake watersheds in the seven-county region surrounding Minneapolis-St. Paul, Minnesota. A geographic information system (GIS) was used to record and measure landscape variables derived from aerial photos. Twenty-seven watershed land-use and land-cover variables were reduced to eight principal components which described 85% of the variance among watersheds. Relationships between lake water quality variables and the first six principal components plus an index of lake mixis were analyzed through stepwise multiple regression analysis. A combination of three landscape components (wetland/watershed area, agriculture/wetlands, and forest/soils components) explained 49% of the variance in a trophic state index, even though most of the lakes examined were already highly eutrophic, and thus were influenced by internal loading. The regression equations explained a range of 14 to 76% of the variation in individual water quality variables. Forested land-use was associated with lower lake trophic state, chloride, and lead. High lake trophic state was associated with agricultural land-use and with wetland distance from the lake of interest. The extent of wetlands was associated with low total lead and high color in lakes downstream. Wet meadows or herbaceous, seasonally-flooded wetlands contributed more to lake water color than did cattail marshes.  相似文献   

乌梁素海湿地环境与资源地理信息系统的研究   总被引：6，自引：0，他引：6  

尚士友  吴利斌  郁志宏  岳海军  李洁  马清艳 《干旱区资源与环境》2003,17(5):59-64

本系统建立乌梁素海湿地基础地形库、生态库、资源库、工程档案库、遥感影像库等基础数据库及信息发布系统 ,使 GPS、GIS、RS紧密结合 ,同时实现了专家决策支持系统与地理信息系统之间的一体化集成。本系统可以为乌梁素海湿地生态治理与资源开发提供全方位的数据信息及其管理 ,对生态工程规划与实施方案进行优化设计 ,并提供实时监控服务。  相似文献   

乌梁素海生态恢复机理与工程技术的研究   总被引：2，自引：1，他引：2  

尚士友  杜健民  厚福祥  申庆泰  王丽敏 《干旱区资源与环境》2003,17(6):50-54

在我国干旱区典型草型湖泊—乌梁素海设立试验基地 ,进行生态恢复工程试验研究。研究表明 :乌梁素海受富营养化影响 ,正在向芦苇沼泽—碱蓬盐化草甸—白刺荒漠方向演化。生态恢复机理是 :( 1 )减少大型水生植物有机氮、磷向底质的沉降 ,削弱内源性营养物负荷的积累与储备 ;( 2 )减少大型水生植物死亡后矿化成氨态氮 ;( 3)控制底质中有机氮向水体释放生成氨态氮。采用机械化方式收割大型水生植物转移营养盐 ,抑制生物促淤效应以及对芦苇区进行园田化生态管理是乌梁素海生态恢复的关键技术 ,也是乌梁素海环境与资源持续发展的核心问题  相似文献   

额济纳旗浅层地下水环境研究   总被引：1，自引：0，他引：1  

苏永红  冯起  朱高峰 《干旱区资源与环境》2004,(Z2)

通过 2 0 0 3年 4- 5月在黑河下游额济纳分两条路线 (a -a’和b -b’)采集水样 ,分析了额济纳现状水资源特征。远离河道区域水化学类型有HCO3·SO4-Na、Cl·SO4-Na·Ca、HCO3·Cl-Na·Ca和SO4·Cl-Na ;在河道附近或河道地区水化学类型主要是SO4·HCO3-Na ,类型单一 ;研究区矿化度和各离子含量随距离补给源的远近增减而升降 ,表明它们主要依赖于上游补给水量 ;同时 ,额济纳地处干旱区 ,降雨稀少 ,该区植被的生长发育主要依靠浅层地下水 ,地下水环境的改变直接导致了区域生态的变化。  相似文献   

Yield Performance of Wheat Isolines with Different Dosages of the Short Arm of Rye Chromosome 1          下载免费PDF全文

D. C. Maheepala  B. Ehdaie  J. G. Waines 《Journal of Agronomy and Crop Science》2015,201(2):152-160

Translocations of the short arm of rye (Secale cereale L.) chromosome 1 (1RS) in wheat (Triticum aestivum L. cv. Pavon 76) are known to increase root biomass. Such an increase enhances water and nutrient uptake and may improve grain yield. Two greenhouse experiments and a field experiment were carried out at the University of California, Riverside, in 2012 and 2013 under well‐watered and terminal drought treatments to evaluate phenotypic characters associated with varying dosages of 1RS, including grain yield. The genotypes used were cultivar Pavon 76 (R₀), Pavon 76/Pavon1RS.1AL (F₁ hybrid) with a single dosage of 1RS (R₁A), Pavon 1RS.1AL with two dosages of 1RS (R₂A), Pavon 1RS.1DL (R₂D) also with two dosages of 1RS and Pavon 1RS.1AL‐1RS.1DL (R₄AD) with four dosages of 1RS. There was a significant positive correlation between number of dosages of 1RS and root biomass. However, no correlation was found between root biomass and grain yield per plant. Drought in the field experiment reduced grain yield significantly. Under well‐watered field conditions, grain yield of R₂A (215.9 g plant^?1) was significantly greater than those of R₂D (191.8 g plant^?1) and R₄AD (161.7 g plant^?1). Also, grain yield of R₄AD was significantly less than those of F₁, Pavon 76 and R₂D under well‐watered conditions. Under drought field conditions, no significant differences were found among the genotypes for grain yield was found between F₁ (14.7 g plant^?1) and R₄AD (12.4 g plant^?1). Harvest index was significantly greater in well‐watered (44.2 %) than in drought (34.6 %) field conditions. On average, genotypes F₁ (42.3 %) and R₂A (40.6 %) had higher harvest index than R₂D (38.3 %) and R₄AD (35.5 %) in the field. Also, Pavon 76 (40.2) and R₂D (38.3) had higher harvest index than R₄AD. Drought tolerance was lowest for R₄AD due to its relatively lower grain yield potential. In general, Pavon 1RS.1AL carrying two dosages of 1RS showed higher grain yield under wet treatments. Pavon 1RS.1AL‐1RS.1DL carrying four dosages of 1RS produced the largest shoot and root biomasses, but the least grain yield.  相似文献   

Population‐level effects of egg predation on a native planktivore in a large freshwater lake     

David B. Bunnell  Justin G. Mychek‐Londer  Charles P. Madenjian 《Ecology of Freshwater Fish》2014,23(4):604-614

Using a 37‐year recruitment time series, we uncovered a field pattern revealing a strong, inverse relationship between bloater Coregonus hoyi recruitment success and slimy sculpin Cottus cognatus biomass in Lake Michigan (United States), one of the largest freshwater lakes of the world. Given that slimy sculpins (and deepwater sculpin Myoxocephalus thompsonii) are known egg predators that spatiotemporally overlap with incubating bloater eggs, we used recently published data on sculpin diets and daily ration to model annual bloater egg consumption by sculpins for the 1973–2010 year‐classes. Although several strong year‐classes were produced in the late 1980s when the proportion of eggs consumed by slimy sculpins was extremely low (i.e., <0.001) and several weak year‐classes were produced when the proportion of bloater eggs consumed was at its highest (i.e., >0.10–1.0), egg predation failed to explain why recruitment was weak for the 1995–2005 year‐classes when the proportion consumed was also low (i.e., <0.02). We concluded that egg predation by slimy and deepwater sculpins could have limited bloater recruitment in some years, but that some undetermined factor was more important in many other years. Given that slimy sculpin densities are influenced by piscivorous lake trout Salvelinus namaycush, the restoration of which in Lake Michigan has lagged behind those in lakes Superior and Huron, our study highlights the importance of an ecosystem perspective when considering population dynamics of fishes.  相似文献   

达里诺尔湖湿地生态系统服务价值评价     

郝伟罡  申军  崔丽萍  焦瑞  刘虎  刘华琳 《中国农学通报》2020,36(36):40-43

生态系统服务功能是生态系统与生态过程所形成及所维持的人类赖以生存的自然环境条件与效用,对其服务价值进行货币化评价,可以推动自然资源可持续利用,促进区域生态环境保护。以达里诺尔湖湿地为研究对象,结合达里诺尔湖湿地生态系统的结构、特征及其生态过程特点,通过资料搜集与实地调研,运用资源经济学理论和方法,对达里诺尔湖湿地生态系统服务价值进行了划分。构建了达里诺尔湖湿地生态系统服务价值评价指标体系,并对其进行了价值评价。评价结果显示达里诺尔湖湿地的服务价值为93.70×10⁴万元,其中直接使用价值为2.19×10⁴万元,占比为2.36%,间接使用价值为91.51×10⁴万元,占比为97.66%。各项生态系统服务功能中以调节空气湿度价值最大,为82.76×10⁴万元,占总服务价值的88.32%。  相似文献   

Selecting fish‐based metrics responding to human pressures in French natural lakes and reservoirs: towards the development of a fish‐based index (FBI) for French lakes     

L. Launois  J. Veslot  P. Irz  C. Argillier 《Ecology of Freshwater Fish》2011,20(1):120-132

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复合材料模型分析加筋地基承载力     

沈超  王钊 《中国农村水利水电》2005,(5):57-59

利用复合材料模型模拟加筋地基，按照土塑性力学分析加筋地基的变形和破坏，并按传统滑移线解法推导出浅基础加筋地基的承载力设计公式，利用实例比较探讨了本文方法与传统极限分析法的优缺点。  相似文献   

加快洞庭湖区农机化发展 促进社会主义新农村建设     

江波  黄瑞英  汤楚宙 《湖南农机》2006,(7)

建设社会主义新农村是我党今后很长一段时期的重大历史任务。新农村建设使洞庭湖区农机化获得了发展良机,而农机化在新农村建设中的地位和作用显著,本文从湖南洞庭湖区新农村建设的要求出发,提出了大力推广水稻生产全程机械化技术,以促进洞庭湖区农村生产发展、农民生活宽裕;坚持依法行政,保障农机安全生产,以促进农村社会和谐,乡风文明;抓好农机部门自身建设,以适应社会主义新农村建设的需求等几项措施。  相似文献