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1.
The reproduction dynamics of nonsynanthropic rodents living in urbanized areas was compared with that of rodents from natural communities. The number of females in a community and the number of embryos and placental spots per female were estimated. The mechanisms providing for the maintenance of population size were different in different habitats. In particular, the urban communities of murine rodents proved to have a higher reproductive potential.  相似文献   

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The formation of the species composition and specific functional, physiological, and phenotypic features of populations in technogenic and urbanized areas was studied by analyzing murine rodents, amphibians, and soil invertebrates. It is shown that, against the background of decreasing total abundance and biomass of animals, their formerly continuous ranges become mosaic, with the locally increasing animal density and heterogeneity and specific population dynamics. Species diversity decreases; however, species alien to the natural ecosystems of the given territory appear. Changes in the strategies of reproduction and food resource use were revealed in the species communities of small mammals and amphibians.  相似文献   

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For the first time, zooplankton and environmental factors have been studied in winter in the deep stratified lakes Siverskoe, Borodaevskoe, and Vydogoshch. The zooplankton consists of 18–22 species of rotifers, copepods, and cladocerans, including 15–18 specifically winter, cryophilic and eurythermic forms. The populations of zooplankters reproduce actively: males and egg-bearing females (in copepods), females with embryos and eggs in brood pouches (in cladocerans), and females with attached eggs (in rotifers) are present. In lakes Siverskoe and Borodaevskoe (depth 20–24 m), where oxygen deficiency is observed only in the bottom water layer, the zooplankton populates the greater part of the water column and forms a large aggregation in the oxycline and near the bottom. The abundance of bacteria in these zones is high (up to 4–6 × 106 cells/ml). In Lake Vydogoshch (depth 16 m), oxygen deficiency extends to the middle layers, and all zooplankton is distributed above the oxycline. The biomass of winter zooplankton in Lake Siverskoe in 1983 averaged 1.26 g/m3, with a maximum of 4 g/m3; in 1993, 1.4 and 8.04 g/m2; the respective values in Lake Borodaevskoe were 0.98 and 3.1 in 1983 and 0.14 and 1.6 in 1993; in Lake Vydogoshch, 0.15 and 0.24 in 1983 and 1.25 g/m3 in 1993. The development of winter zooplankton is limited by the size of the zone of oxygen deficiency and depends on the amount of food (bacterioplankton). The distribution of zooplankton in the water column and its biomass in individual layers is determined by the rate of methane formation and oxidation.__________Translated from Ekologiya, No. 3, 2005, pp. 201–214.Original Russian Text Copyright © 2005 by Rivier.  相似文献   

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Two populations of creeping thistle (Cirsium arvense) growing in a field uncultivated for many years and on the sloping bank of an artificial pond were studied with respect to the demographic and chemical composition. The results showed that the contents of some elements in plants depend on specific features of the soil and plant population parameters (abundance, biomass, and ontogenetic composition). Some indices of the content of mineral substances in the population and soil proved to be difficult to interpret unambiguously.  相似文献   

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The ichthyofauna of 20 small ponds in the Udmurt Republic was studied to estimate the dependence of fish species abundance on pond size and anthropogenic load, as well as trends in the succession of dominant species complexes in ponds exposed to the prevailing impact of agricultural activity. Changes in the ecological structure of fish communities in small ponds upon an increase in the anthropogenic load were analyzed. Some specific features of the species composition of ichthyofauna in technogenic pond biocenoses were revealed.  相似文献   

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城市化改变了洪涝灾害风险的孕灾环境、致灾因子和承灾体的脆弱性,相应地,洪涝灾害的风险也随之加大了。在这种大环境下,采取合理可行的防洪减灾对策来降低洪涝风险就变得非常重要了。笔者认为应采取工程措施和非工程措施相结合的防洪减灾对策,工程措施方面主要包括提高防洪堤的防洪标准、提高城市排水能力、提高城市广场和绿地的占地面积、铺设楼顶蓄水池和地下蓄水池,非工程措施方面主要包括做好防洪规划、加强防洪评价,进行洪涝灾害风险分析,加强洪水预报预警工作,普及城市居民的防灾意识。  相似文献   

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The data on the dynamics of population size and species composition of wasps from the families Pompilidae, Sphecidae, and Vespidae were obtained in the course of long-term studies carried out in successional pine forests of the Berezinskii Biosphere Reserve. The abundance and species diversity of wasps were significantly higher in a polewood forest (40 years) than in a young forest (20 years) and mature moss forest (70 years). In an overgrown ride in the moss pine forest, the composition of dominant wasp species remained relatively stable during the seven-year period of observations, although the number of species and their abundance varied significantly from year to year, depending on the weather.  相似文献   

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The results of long-term studies on phytoplankton in the cooling reservoir of the Beloyarsk Nuclear Power Plant (the Middle Urals) are reviewed. Altogether, 199 taxa of the species and subspecies rank have been recorded, including 144 taxa described in this water body for the first time. The algoflora of the reservoir consists mainly of widespread and eurybiontic freshwater species.  相似文献   

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ABSTRACT

This essay examines the mediation of the threat of Asian carp as an invasive species in American waterways based on analysis of 43 articles published in local and national periodicals from 2009 to 2017. Rhetorical and proximization analysis reveals the consistent establishment of carp as an outsider threat and a continual narrowing of the gap between this threat and the deictic center: the Great Lakes. In addition, the notion of the spectacle of the Asian carp’s physiological and behavioral features (i.e. leaping) was found to fade across time in favor of arguments based upon widespread ecosystem and economic damage. This essay argues that the use of these yoked strategies not only prioritizes the threat of Asian carp over other more insidious invasive species but also displays a potentially harmful anti-immigrant preference through metaphor.  相似文献   

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Species composition of fishes was studied in rivers (capture sites) inhabited by the riffle minnow. In some localities, this species proved to occupy a leading position in the ichthyofauna, being obviously dominant. In small rivers, 16 species were caught together with it, including seven species regularly occurring in catches. The relative abundance of riffle minnow showed a moderate positive correlation with that of the gudgeon (0.568) and a nonsignificant negative correlation (?0.399) with that of the bleak. It is probable that the population dynamics of riffle minnow are determined mainly by natural intraspecific mechanisms rather than by water quality, which has changed only slightly in the rivers studied.  相似文献   

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During the last 50 years the practising and intensity of agriculture and forestry have differed considerably between Finnish and Russian Karelia. We studied the effects of different land use practices on the landscape composition in the two countries using the road transect sampling along four study routes (99-121 km) between 1997 and 1999. Effective environmental management in Finland has resulted in more distinct agricultural land types, more even distribution of the different age classes of forests, and the higher abundance of coniferous forests. Fields (mean percentage of the landscape: Finland 28%, Russia 13%), clearcuts and sapling stands (15%, 6%), and young forests (23%, 9%) were more typical elements of the Finnish landscape, whereas settlements (9%, 13%), semi-natural grasslands (3%, 7%), and mature forests (20%, 49%) were more characteristic of the Russian landscape. Landscape-level differences between the two countries may have various effects on the diversity of fauna and flora inhabiting Finnish and Russian Karelia.  相似文献   

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全球气候变暖是人类面临的严峻挑战,稻田生态系统在全球气候变暖中起到重要的作用。目前已有许多学者通过大田试验的方法研究了不同秸秆还田方式下温室气体排放的特征,但由于试验地点等因素的不同导致最终的结果差异很大。通过整合这些结果来研究区域内不同秸秆还田方式(翻耕秸秆还田(CTS)、免耕秸秆还田(NTS)和旋耕秸秆还田(RTS))下稻田温室气体排放的特征,能够准确地反映一定区域内稻田生态系统的净减排潜力。本文基于长江中下游地区32篇关于秸秆还田对稻田温室气体排放的文献收集173组数据,利用Meta分析方法研究了3种秸秆还田方式下稻田CH_4和N_2O排放的特征,并估算出不同秸秆还田方式下稻田的全球增温潜势和净增温潜势。结果表明,CTS、NTS和RTS处理下稻田CH_4周年排放的效应值分别为0.76、0.37和0.68,稻田N_2O周年排放的效应值分别为0.44、0.36和0.52;在两熟制下,不同秸秆还田方式下稻田CH_4周年排放的效应值的大小为RTSCTSNTS,但N_2O周年排放的效应值的大小为RTSNTSCTS。在三熟制下,三种秸秆还田方式下稻田CH_4的周年排放的效应值的高低为CTSRTSNTS,而N_2O周年排放的效应值的高低为RTSNTSCTS。在相同的秸秆还田方式下,三熟制稻田温室气体周年排放的效应值都高于两熟制。此外,不同的还田秸秆种类影响稻田温室气体的排放;结合前期研究,估算出CTS、NTS和RTS处理下稻田的净增温潜势分别为12 375.55、11 232.36和15 982.87 kg CO_2-equivalent·hm~(-2)。因此,免耕秸秆还田是长江中下流地区稻田净减排条件下适宜的秸秆还田方式。  相似文献   

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The data presented were obtained at the first stage (1993–1999) of studies on evaluating the basic parameters of biological production in Russian terrestrial ecosystems in order to provide information for assessing and modeling the carbon budget of the entire terrestrial biota of the country. Stocks of phytomass (by fractions), coarse woody debris, and dead roots (underground necromass) were calculated by two independent methods, which yielded close results. The total amount of phytomass in Russian terrestrial ecosystems was estimated at 81800 Tg (=1012 g = million t) dry matter, or 39989 Tg carbon. Forest ecosystems comprise a greater part (82.1%) of live plant organic matter (here and below, comparisons are made with respect to the carbon content); natural grasslands and brushwoods account for 8.8%; the phytomass of wetlands (bogs and swamps), for 6.6%; and the phytomass of farmlands, for only 2.5%. Aboveground wood contains approximately two-thirds of the plant carbon (63.8%), and green parts contain 9.9%. For all classes of ecosystems, the proportion of underground phytomass averages 26.7% of the total amount, varying from 22.0% in forests to 57.1% in grasslands and brushwoods. The average phytomass density on lands covered with vegetation (1629.9 million hectares in Russia) is 5.02 kg/m2 dry matter, or 2.45 kg C/m2. The total amount of carbon in coarse woody debris is 4955 Tg C, and 9180 Tg C are in the underground necromass. In total, the vegetation of Russian terrestrial ecosystems (without litter) contains 54124 Tg carbon.  相似文献   

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