检索结果-南通市图书馆

Macroinvertebrate　assemblages　of　surface　mine　wetlands　of　Southwest　Virginia，usa

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 1996年第1期8卷 1-14页

作者： David H.Jones Robert B. Atkinson John Cairns,Jr.(Department of Biology,Virginia Polytechnic Institute and State University, Blacksburg,Virginia 24061 usa) Dept Biol Virginia Poly Inst Blacksburg VA 24061 United States

The focus of this study was to investigate the macroinvertebrate community in surface mine wetlands. Nine wetlands were sampled for macroinvertebrates from July 1993 through May *** sites represented a range of physical,chemical, and biological parameters. Macroinvertebrates were found in all sites;a total of 14 orders, 40 families,and 70 genera were identified in the samples. Insects were the most common invertebrates,and most functional feeding groups were represented. Predators dominated with 63% of the taxa, followed by the collector/gathers with 20%,shredders 14%, and scrapers 3%. Sites differed in the number of taxa inhabiting *** ranged from 10 genera to *** lowest richness was found in two seasonal wetlands that were dry for the majority of the year. A permanently flooded site with no water quality problems and a dense growth of aquatic plants had the highest richness.

关键词： macroinvertebrate assemblages surface mine wetlands wetland faunas.

Comparison of Soil Biota Between Organic and Conventional Agroecosystems in Oregon, usa

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2005年第3期15卷 395-403页

作者： WUShan-Mei HUDun-Xiao E.R.INGHAM UniversityofCalifornia BerkeleyCA94720（USA） ChinaAgriculturalUniversity Beijing100094（China） OregonStateUniversity CorvallisOR（USA）

Soil samples at 0-10 cm in depth were collected periodically at paired fields in Corvallis, Oregon, usa to compare differences in soil microbial and faunal populations between organic and conventional agroecosystems. Results showed that the organic soil ecosystem had a significantly higher (P < 0.05) average number or biomass of soil bacteria; densities of flagellates, amoebae of protozoa; some nematodes, such as microbivorous and predaceous nematodes and plant-parasitic nematodes; as well as Collembola. Greater numbers of Rhabditida (such as Rhabditis spp.), were present in the organic soil ecosystem while Panagrolaimus spp. were predominant in the conventional soil ecosystem. The omnivores and predators of Acarina in the Mesostigmata (such as Digamasellidae and Laelapid), and Prostigmata (such as Alicorhaiidae and Rhagidiidae), were also more abundant in the organic soil ecosystem. However, fungivorous Prostigmata (such as Terpnacaridae and Nanorchestidae) and Astigmata (such as Acarida) were significantly higher (P < 0.05) in the conventional soil ecosystem, which supported the finding that total fungal biomass was greater in the conventional soil ecosystem. Seansonal variations of the population depended mostly on soil moisture condition and food web relationship. The population declined from May to October for both agroecosystems. However, higher diversities and densities of soil biota survived occurred in the organic soil ecosystem in the dry season.

关键词： microarthropods nematodes organic and conventional agroecosystems soil microbial population

Morpho-sedimentary unit signatures associated with micro-estuaries in Barnegat Bay national estuary,New Jersey,the usa

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第S1期46卷 62-65页

作者： Norbert P. PsutyDepartment of Marine and Coastal Sciences, Cook College, Rutgers University, New Brunswick, New Jersey 08901, usa (e-mail: psuty@ imcs.rutgers.edu) Rutgers State Univ Dept Marine & Coastal Sci New Brunswick NJ 08901 USA

Incorporation of the Barnegat Bay into the US National Estuary Program has triggered collection and collation of basic data sets appropriate to estuarine management. Gathering of water quality and quantity as well as basic geological data is adding to the knowledge of the complexity of the bay. An ongoing program of systematic sampling of bottom sediments in the large bay and intense sampling in the many micro-estuaries along the mainland margin is demonstrating the presence of localized mor-pho-sedimentological units related to the interaction of the fluvial, tidal, and wave processes active in the bay. Mean grain sizes and standard deviation measures assist in the development of signatures of bottom sediment types.

关键词： lagoon estuary bottom sediment wave and tidal dy- namics

Spatial Variability of Soil Properties at Capulin Volcano,New Mexico,usa:Implications for Sampling Strategy

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2010年第2期20卷 185-197页

作者： D.C.WEINDORF School of Soil Plant and Environmental SciencesLouisiana State University

Non-agricultural lands are surveyed sparsely in ***,soils in these areas usually exhibit strong spatial variability which requires more samples for producing acceptable *** Volcano National Monument,as a typical sparsely-surveyed area,was chosen to assess spatial variability of a variety of soil properties,and furthermore,to investigate its implications for sampling *** hundred and forty one composited soil samples were collected across the Monument and the surrounding *** properties including pH,organic matter content,extractable elements such as calcium (Ca),magnesium (Mg),potassium (K),sodium (Na),phosphorus (P),sulfur (S),zinc (Zn),and copper (Cu),as well as sand,silt,and clay percentages were analyzed for each *** of all properties were constructed,standardized,and compared to estimate the spatial variability of the soil properties in the *** on the similarity among standardized semivariograms,we found that the semivariograms could be generalized for physical and chemical properties,*** generalized semivariogram for physical properties had a much greater sill value (2.635) and effective range (7 500 m) than that for chemical *** sampling density (OSD),which is derived from the generalized semivariogram and defines the relationship between sampling density and expected error percentage,was proposed to represent,interpret,and compare soil spatial variability and to provide guidance for sample scheme *** showed that chemical properties exhibit a stronger local spatial variability than soil texture parameters,implying more samples or analysis are required to achieve a similar level of precision.

关键词： generalized semivariogram GIS optimal sampling density sampling design