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361.
沈阳城市森林主要树种叶片形态生态特征与生长规律 总被引:3,自引:2,他引:1
利用统计和多元分析方法研究了沈阳城市森林10个主要树种叶片的形态生态特征和生长规律.结果表明,影响树木叶片生长发育节律的主要气象因子是≥5 ℃积温、累积日照时数和各物候期中旬平均温度.不同物候期树木所需要的气象因子有所变化,树木萌动期要求低温和寒冷指数,而在生长期需要一定的温暖指数和湿润指数.10个树种的叶片形态数量特征差异较大,按叶形指数依次为短序胡枝子>华北丁香>国槐>银白杨>红瑞木>金银忍冬>水腊>水曲柳>稠李>黄菠萝;按叶面积依次为华北丁香>银白杨>黄菠萝>稠李>水曲柳>红瑞木>短序胡枝子>金银忍冬>国槐>水腊.在10个树种叶长度与宽度、周长、叶面积之间相互关系中,基本属于异速生长类型,符合y=axk模型,但在叶长度与宽度之间关系中,除银白杨k>1外,其它9个树种均k<1;在叶长度与周长关系中,黄菠萝k>1, 银白杨k≈1,呈线性关系,其它树种均k<1;在叶长度与叶面积关系中,10个树种k>1,而 银白杨k=2.1028,叶面积增长速率近似于叶长的2倍.建立了10个树种的叶面积最优回归估测模型,并对模型进行了估测检验. 相似文献
362.
363.
This research was designed to compare allergenic flora of various cities of central Italy. Because the data on this problem
are rather scant, we wanted to highlight the relationships among the ecological conditions of the urban habitats, and the
plants whose pollens cause allergic manifestations in the human population. Our results pointed out that the structural design
of the urban land use types play an important role in the distribution of allergophytes. The compact structure of the historic
city center does not impede the establishment of allergophytes. Actually, it promotes some species that come from the dry
pastures and rocky walls of the surrounding ecosystems. Allergenicity was revealed throughout the urban area, with a prevalence
of species with monoporate pollens characteristic of the Poaceae. Highly allergenic plants are present in the central zone (within the city walls) and in some peripheral land use models
(urban road verges). The particular abundance of Urticaceae with small triporate pollen grains and of various cultivated species, introduced by man for aesthetic reasons, contributes
to the increase of allergophytism. The study points out the role of the interactions between the allergenic flora, human impact
through the land use patterns, urban fauna, and the meso- and microclimatic conditions of the cities studied. 相似文献
364.
Sonja Knapp Ingolf Kühn Volker Mosbrugger Stefan Klotz 《Biodiversity and Conservation》2008,17(7):1595-1612
Previous studies from Central Europe and North America showed that species richness is higher in urban than in rural landscapes. Do protected areas, which can be found in both city and countryside, reflect this species richness pattern? The impact of urban land-use might reduce conservation success and necessitate special management strategies. We compared species richness and species spatial turnover of selected animal and plant taxa (carabids, butterflies, snails, birds, lichens, mosses, vascular plants) in 30 protected areas in the city of Halle and 56 protected areas in the adjacent rural district of Saalkreis (Central Germany). Species were mapped by experienced biologists within a systematic species inventory. We corrected species numbers for the effects of landscape structure (e.g. size, shape and distance of habitats) which might influence species diversity beyond urbanisation effects. Butterflies, birds and lichens had significantly higher species numbers in the rural protected areas. Species spatial turnover was higher among urban areas than among rural areas or pairs of urban and rural areas for most taxa. Diversity in all taxa depended on the size of a protected area. We discussed these patterns in the context of the general urban-rural species diversity patterns. Our results indicate an increasing isolation of species assemblages with urbanisation and highlight that space for protected areas is even more limited in urban than rural areas. An effective conservation of urban species diversity should include both typical urban and semi-natural habitats to cover the full range of species living in cities. 相似文献
365.
利用不育技术防治高原鼠兔的理论模行 总被引:1,自引:0,他引:1
高原鼠兔数量的激增加剧了高寒草甸的退化,采取化学灭杀的方法控制高原鼠兔,只能暂时降低高原鼠兔的数量,在较短的时间内种群又会恢复到原来的水平.本文从理论上探讨不育控制对高原鼠兔种群的影响,建立了具有性别结构的高原鼠兔种群的数学模型,探讨在不育控制中两性的不育率对种群动态的影响并比较不育控制与化学灭杀的区别.结果表明:不育控制比化学灭杀在抑制和消灭种群上都具有更好的效果;在不育控制中雌性的不育率具有更为重要的作用,所以在利用不育技术控制高原鼠兔时要特别注意雌性不育率. 相似文献
366.
Abstract. A method is discussed for describing the intensity of disturbance, based on the floristic composition of vegetation types. It includes the development of a hemerobiotic scale (from hemeros= cultivated). We attempted to relate this scale based on floristic patterns with functional parameters. Following a large phytosociological survey of the Roman area, we selected 19 species of herbs and grasses, widely differing in ‘hemeroby’, and measured their Relative Growth Rate (RGR). RGR varies between 0.13 and 0.21 d‐1. A significant correlation between mean hemerobiotic value, resulting from the phytosociological study, and measured RGR of juvenile plants emerges. Although Specific Leaf Area (SLA) is highly correlated with RGR, and thus explains most of its variations, as previously found in other studies, it is only weakly related to hemerobiotic state. An additional data set with 78 species from the literature supports the conclusions. This approach allows a functional quantification of hemeroby which enables useful applications, for instance in cartography. A biotope map showing a steep gradient of disturbance impact in the city of Rome is presented as a preliminary test. 相似文献
367.
The chemical analysis of urban Toronto airborne particulate matter (PM), size segregated into respirable PM10/2.5, is presented.
The characterization of PM by use of proton-induced X-ray emission analysis (PIXE), and inductively coupled plasma-atomic
emission spectrometry revealed elemental information; a newer laser ablationionization mass spectrometry approach has the
potential to expand the chemical information from PM by analyzing both the inorganic and organic species. These PM analytical
approaches will be continued in the future for studying (1) emission source identification, (2) inhalation health hazards,
and (3) urban smog chemistry. 相似文献
368.
We analyzed the variation in island bird communities of urban environments related to habitat characteristics, using regression/classification tree analyses. Data from field censuses in cities/towns representing the urban heterogeneity of the whole island were obtained in Tenerife (Canary Islands, Spain). Urban bird abundance in Tenerife was negatively affected by altitude and the cover of dry Euphorbia shrubs and positively influenced by the height and cover of the tree layer. Species richness was negatively associated with building cover and positively related to tree height and altitude. Data from field censuses in Tenerife were compared with that of similar urban environments in the mainland (Madrid Province, central Spain). Species diversity was higher in the urban sample of Tenerife than in that of Madrid and the proportion of bird species from the regional pool captured by urban environments was higher in the island than in the mainland. Nine native species and three alien species were more abundant in island urban environments than in the continent (densities, at least, 100% higher), the converse occurring for only five species. At a biogeographic scale, we conclude that the avifauna of Tenerife Island is more prone to occupy a new artificial environment than the mainland bird fauna of central Spain. 相似文献
369.
Role of benthic diatoms in the implementation of the Urban Wastewater Treatment Directive in the River Wear, North-East England 总被引:3,自引:0,他引:3
M.G. Kelly 《Journal of applied phycology》2002,14(1):9-18
The use of diatoms to monitor rivers in the UK was stimulated largely bythe requirements of the European Union's Urban Wastewater TreatmentDirective. The Trophic Diatom Index (TDI) was developed to assist theinterpretation of benthic diatom assemblages from UK rivers. This paperdescribes how data collected from one river, the River Wear in N-E England,sampled over a five-year period, was used to provide information about thepotential benefits of nutrient removal on major sewage treatment works.Althoughthe TDI indicated a clear increase in eutrophication with distance downstream,interpretation was confused by considerable within-site variability.Multivariate techniques such as TWINSPAN, when used alongside diatom indices,provide a more rigorous interpretation of longitudinal changes. The potentialfor using statistical power analysis to design sensitive monitoring programsusing benthic diatoms is also described. 相似文献
370.
Malgorzata?LatalowaEmail author Monika?Badura Joanna?Jarosińska 《Vegetation History and Archaeobotany》2003,12(2):93-104
The botanical composition of samples from culture layers, explored in two medieval towns in northern Poland, is discussed with respect to their potential as a source of environmental data. The frequency of selected taxa and the proportion of their diaspores in the actualistic groups of weed and grassland species, as well as the distribution of indices for edaphic factors were used as indicators of the natural environment around and inside the towns, and of some aspects of agriculture. The comparison of the results from both towns affords new evidence for a better understanding of archaeobotanical data from culture layers of non-specific, complex origin. 相似文献