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31.
自然保护地不仅对保护生物多样性具有重要意义,也在减缓气候变化、实现碳中和目标方面起到关键作用。中国自然保护地的碳中和贡献尚未得到充分的认识和关注,相关研究尚处于起步阶段。首先对中国陆域自然保护地的碳储量、碳吸收能力、人为碳排放水平展开初步评估,发现陆域自然保护地在保护高碳中和贡献生态系统方面存在不足。随后提出了中国自然保护地碳中和贡献研究的3个关键课题,分别是自然保护地碳循环作用机理研究、自然保护地碳中和贡献评估与管理、生物多样性保护和碳中和的协同治理。最后围绕关键课题提出14个具体研究问题,为中国自然保护地减缓气候变化的科学研究与管理实践构建系统框架。 相似文献
32.
目前国内对海绵生境生物多样性方面的研究还较为欠缺,有蓄水功能的塘类海绵生境可作为鸟类觅食及栖息之地。为了探究塘类海绵生境的鸟类特征,以及生境中的设计与环境因子是如何影响鸟类群落多样性特征的,对重庆悦来会展城的干塘与湿塘进行调查,采集生境中的鸟类、植被、面积特征与环境干扰特征数据。采用聚类分析的方法明确鸟类群落组成特征,通过构建结构方程模型,探究塘类海绵生境特征因子对鸟类群落多样性特征的影响。经过四季监测实地调研,总共观测到64种鸟类,可划分为4种鸟类集团,整体鸟类群落多样性特征受到生境面积、蓄水层面积、乔木多样性、灌木多样性、乔木胸径、乔木盖度、噪声、距林地距离和距非绿地建设用地距离的显著影响。通过合理的设计策略可以提升塘类海绵生境鸟类多样性特征。本研究对于探索城市绿地小微生境的生物多样性效益,促进海绵城市精细化营建具有重要价值。 相似文献
33.
长三角一体化绿色发展是中国的重大战略,乡村生态状况是长三角城市群生态健康发展的基础。针对长三角城市群乡村植被生物多样性保育和生态系统服务功能提升需求展开研究,调研了28个乡村共256个植物群落样地,分别进行了科属种构成和生活型分析;通过群落聚类,划分出47个群落类型和8个植被型,分析了植物群落构成和分布特征;进行了物种生物多样性分析,并将长三角乡村植被特征与城市区域和自然区域的植被特征进行比较;最后,从物种保护、生境维护、群落保育和生态美学引导等方面提出了长三角乡村植被生物多样性保育与构建的具体对策。 相似文献
34.
M. C. Freeman G. R. Buell L. E. Hay W. B. Hughes R. B. Jacobson J. W. Jones S. A. Jones J. H. Lafontaine K. R. Odom J. T. Peterson J. W. Riley J. S. Schindler C. Shea J. D. Weaver 《河流研究与利用》2013,29(7):906-918
Efforts to conserve stream and river biota could benefit from tools that allow managers to evaluate landscape‐scale changes in species distributions in response to water management decisions. We present a framework and methods for integrating hydrology, geographic context and metapopulation processes to simulate effects of changes in streamflow on fish occupancy dynamics across a landscape of interconnected stream segments. We illustrate this approach using a 482 km2 catchment in the southeastern US supporting 50 or more stream fish species. A spatially distributed, deterministic and physically based hydrologic model is used to simulate daily streamflow for sub‐basins composing the catchment. We use geographic data to characterize stream segments with respect to channel size, confinement, position and connectedness within the stream network. Simulated streamflow dynamics are then applied to model fish metapopulation dynamics in stream segments, using hypothesized effects of streamflow magnitude and variability on population processes, conditioned by channel characteristics. The resulting time series simulate spatially explicit, annual changes in species occurrences or assemblage metrics (e.g. species richness) across the catchment as outcomes of management scenarios. Sensitivity analyses using alternative, plausible links between streamflow components and metapopulation processes, or allowing for alternative modes of fish dispersal, demonstrate large effects of ecological uncertainty on model outcomes and highlight needed research and monitoring. Nonetheless, with uncertainties explicitly acknowledged, dynamic, landscape‐scale simulations may prove useful for quantitatively comparing river management alternatives with respect to species conservation. Published 2012. This article is a U.S. Government work and is in the public domain in the USA. 相似文献
35.
The differences between urban and rural streams regarding hydrological process, channel morphodynamics and ecosystem functioning have been highlighted by a number of studies in recent decades. The need to understand lotic ecosystem functioning in these environments at scales relevant to individual organisms has led to research focusing on hydraulic composition and structure over small areas of channel bed. In this study we map and analyze the hydraulic biotope composition of two urban and two rural stream reaches in the North Carolina (USA) Piedmont to determine if urban flow regimes and attendant channel modification processes might translate into important differences in hydraulic environment, and if so, what those differences are. Hydraulic biotope assemblages were found to vary only moderately in diversity per unit stream length between sites, but were distinctly different in composition. One important control on the differences between rural and urban streams was found to be the localized incision of urban channels into bedrock and saprolite. Resistant rock outcrop in the beds of urban streams creates rapid and riffle biotopes and long stretches of upstream pool habitat by impoundment. Urban reaches were found to be more homogeneous than rural reaches in hydraulic composition and were dominated by pools. Rural reaches, characterized by copious sandy alluvium in the bed, were dominated by runs or glides. Quantitative differentiation of biotopes based on four hydraulic indices generally yields coherent associations, although these may vary in content. Comparisons between hydraulic and biotic diversities suggest relationships favoring biotic functional group aggregation over species richness‐based indices of diversity. Because the majority of published hydraulic diversity analyses are based on coarse‐bed streams, further study of hydraulic diversity in streams with finer substrate is likely to be beneficial. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
36.
Sean W. Fleming 《河流研究与利用》2005,21(4):363-379
Growing interest in the differential responses of glacial and nival rivers to climatic forcing, and in ecological distinctions between the two streamflow regimes, suggests the need for a better comparative understanding of how the annual hydrologic cycle differs with presence or absence of catchment glacial cover. In this study, timing and magnitude characteristics of the average annual hydrographs of five glacierized and four nival catchments in the southwestern Canadian subarctic are empirically identified and compared. Likely effects upon fish habitat are qualitatively assessed, and net fisheries potential is tentatively investigated using taxa richness data. The chief hydrological conclusions at P < 0.05 using Kolmogorov–Smirnov and empirical orthogonal function analyses are: (1) catchment glacial cover results in freshets that are longer, larger, and peak later than those experienced by the nival regime; (2) the winter baseflows of glacial rivers are also much higher on a unit‐catchment‐area basis; and (3) basin scale and degree of catchment glacial cover are of comparable importance in determining the magnitude of the annual hydrologic cycle. These differences arise from the greater availability, both in volume and over time, of meltwater in glacial catchments, which in part reflects the consistently negative alpine glacial mass balances observed both in the present study area and globally under historical climatic warming. Such regime distinctions result in increased spawning season and winter aquatic habitat availability, which may in turn offset negative habitat characteristics previously identified for glacial river ecosystems. While previous studies have suggested that glacial influences tend to decrease macroinvertebrate diversity and increase salmon populations, preliminary analysis of available fish species presence/absence data from the current study area tentatively appears to suggest similar or, perhaps, slightly higher fish taxa richness relative to nival streams; in all three cases, however, catchment lake cover may play a key hydroecological modifying role. The results strongly confirm and extend existing understanding of glacial–nival regime differences with respect to both streamflow and fisheries ecology, and raise new questions for future research. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
37.
This paper presents the first study of the benthic invertebrate assemblages of the upper section of the Paraguay River, a major tributary to the Pantanal wetland in Brazil. Thirty‐eight sites were sampled along a 200 km section below the city of Cáceres in November 2000. Sixty‐nine species and morphospecies were identified, which were dominated by Oligochaeta and Chironomidae. Mean density of benthic invertebrates varied between 72 and 10 354 m?2 in the meandering sector of the river, 3611–49 629 m?2 in the straight–transitional sectors, 682–5962 m?2 in the floodplain lakes, and 1704–2208 m?2 in floodplain channels. Highest densities were attained in sand‐gravel sediments dominated by the psammophilous oligochaete Narapa bonettoi. The Shannon diversity index ranged from 0.75 to 2.08 and was highest in floodplain lakes. Statistical analysis (UPGMA and CCA) revealed that benthic assemblages in the floodplain habitats were clearly distinct from the riverine habitats. In the river channel, the habitats were distinguished by grain size while the floodplain habitats were mostly determined by current and silt‐clay concentration (floodplain channels) or by organic matter concentration (floodplain lakes). Conservation efforts in the Upper Paraguay area should aim to maintain the flood pulse as a permanent source of spatial and temporal habitat heterogeneity. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
38.
Many valleys in Western Australia have been dammed to provide irrigation and potable water. To minimize the risks of outlet blockages, basins have been cleared of vegetation and rocky outcrops during construction. As a result, dam basins contain limited numbers of aquatic habitats, being dominated by sandy and muddy substrata. Nonetheless, endemic crayfishes (especially marron, Cherax tenuimanus) and three introduced species of fishes support large recreational fisheries in irrigation reservoirs. Recently, it has been shown that Perca fluviatilis (red‐fin perch) imposes an extremely high mortality on C. tenuimanus in reservoirs, with the result that marron populations might be below reservoir‐carrying capacity. To test this hypothesis, three types of artificial habitats (pipes, tiles, mesh) that mimic natural habitat types were placed into a reservoir and their use by C. tenuimanus was assessed. As C. tenuimanus is an annual brooder, releasing young during November and December, the effects of artificial habitats on biomass concentration and productivity can be differentiated. The study results showed that C. tenuimanus rapidly populated artificial habitats (concentration effects). Small, newly recruited C. tenuimanus also utilized the pipe and tile habitats (productivity effects). The addition of these types of habitats increased the suitability of the reservoir for the studied C. tenuimanus population, increasing productivity, probably via reduction of teleost predation. The increased productivity of the C. tenuimanus population might, in turn, increase the productivity and sustainability of the recreational marron fishery. Other aquatic species, including a biofilm community, also utilized the artificial habitats, increasing the species richness in the dam. Due to the success of the current study, large artificial habitats have been installed into two irrigation reservoirs in order to increase recreational marron fishing and conservation values. 相似文献
39.
分离了不同发生地粗柄羊肚菌的内生真菌,并采用常规形态学技术结合ITS序列分析进行了鉴定.结果表明内生真菌具有多样性:从3个发生地采集的羊肚菌子实体中,共分离出属于14个分类单元的16个内生真菌菌株,其中15个菌株为子囊菌或其无性型,仅1个菌株(高山被孢霉)属于接合菌门.毛壳菌为3个发生地共有的内生真菌,Lecanicillium fungicola var.aleophilum仅在四川绵阳和河南郑州采集的羊肚菌子实体中分离到,其他内生真菌均为发生地特异性种类. 相似文献
40.
Alexa Varah Hannah Jones Jo Smith Simon G Potts 《Journal of the science of food and agriculture》2013,93(9):2073-2075
Monoculture farming systems have had serious environmental impacts such as loss of biodiversity and pollinator decline. The authors explain how temperate agroforestry systems show potential in being able to deliver multiple environmental benefits. 相似文献