Interactions between Eisenia andrei (Oligochaeta) and nematode populations during vermicomposting     

Jorge Domínguez  Robert W. Parmelee  Clive A. Edwards 《Pedobiologia》2003,47(1):53-60

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Nitrogenous fertilizers and earthworm populations in agricultural soils     

C.A. Edwards  J.R. Lofty 《Soil biology & biochemistry》1982,14(5):515-521

The influence of various inorganic and organic fertilizers was assessed in three long-term “classical” experiments and two short-term field experiments, one on grass and one on wheat. The long-term experiments included Broadbalk which had grown continuous wheat since 1843, Barnfield, continuous root crops since 1843 and Park Grass, continuous grass since 1836. Annual fertilizer treatments were farmyard manure (48 and 96 kg N ha^?1), various forms of inorganic nitrogen (48, 96, 144 and 192 kg N ha^?1), liquid and solid sewage sludge and sewage cake in a wide range of doses.In the three arable experiments, all species of earthworms were more numerous in plots treated with organic fertilizers than in untreated plots.There was a strong positive correlation (r = 0.9825) between amounts of inorganic N applied and populations of earthworms. Plots receiving both inorganic and organic N had the largest populations of earthworms.The effects of both inorganic and organic N were much less on earthworm populations in grassland than on those in arable crops, even in the long-term experiments, and there was some evidence of adverse effects when an excessive amount of liquid sludge was applied in a single dose.Effects of organic fertilizers were greater on populations of Lumbricus terrestris than on those of Allolobophora longa, A. caliginosa or A. chorotica.  相似文献   

Distribution of phosphorus in soil aggregate fractions and its significance with regard to phosphorus transport in agricultural runoff   总被引：1，自引：0，他引：1  

Z. L. He  M. J. Wilson  C. O. Campbell  A. C. Edwards  S. J. Chapman 《Water, air, and soil pollution》1995,83(1-2):69-84

Surface runoff is the major way of P transport from agricultural land to surface waters. To assess the potential of P loss in runoff in relation to soil P status, the chemical nature and distribution of soil P in different size classes of water-stable aggregates were quantified for two distinctive soil types. For both soils unfertilized areas under pasture and well-fertilized arable soils were sampled. The content of total P, organic P and microbial biomass P (P_mic) decreased in the aggregate size order <0.1, 1–2, and 0.1–1.0 mm respectively. In contrast available P (extracted by Bray I reagent) was lowest in the <0.1 mm aggregate size. Cultivation decreased the percentage of 1–2 mm aggregates but increased that of the <0.1 mm aggregates. Fertilization increased markedly both total P and organic P in the <0.1 mm fraction of arable soils compared to the corresponding samples from unfertilized grassland soils. During aggregate separation, most of P loss was in the form of particulate P and less than 1% in solution. More organic P and P_mic were lost from the grassland soils than from the arable soils.  相似文献   

Thermokarst lakes as a source of atmospheric CH4 during the last deglaciation   总被引：2，自引：0，他引：2  

Walter KM  Edwards ME  Grosse G  Zimov SA  Chapin FS 《Science (New York, N.Y.)》2007,318(5850):633-636

Polar ice-core records suggest that an arctic or boreal source was responsible for more than 30% of the large increase in global atmospheric methane (CH4) concentration during deglacial climate warming; however, specific sources of that CH4 are still debated. Here we present an estimate of past CH4 flux during deglaciation from bubbling from thermokarst (thaw) lakes. Based on high rates of CH4 bubbling from contemporary arctic thermokarst lakes, high CH4 production potentials of organic matter from Pleistocene-aged frozen sediments, and estimates of the changing extent of these deposits as thermokarst lakes developed during deglaciation, we find that CH4 bubbling from newly forming thermokarst lakes comprised 33 to 87% of the high-latitude increase in atmospheric methane concentration and, in turn, contributed to the climate warming at the Pleistocene-Holocene transition.  相似文献   

Recycling endosomes supply AMPA receptors for LTP     

Park M  Penick EC  Edwards JG  Kauer JA  Ehlers MD 《Science (New York, N.Y.)》2004,305(5692):1972-1975

Long-term potentiation (LTP) of synaptic strength, the most established cellular model of information storage in the brain, is expressed by an increase in the number of postsynaptic AMPA receptors. However, the source of AMPA receptors mobilized during LTP is unknown. We report that AMPA receptors are transported from recycling endosomes to the plasma membrane for LTP. Stimuli that triggered LTP promoted not only AMPA receptor insertion but also generalized recycling of cargo and membrane from endocytic compartments. Thus, recycling endosomes supply AMPA receptors for LTP and provide a mechanistic link between synaptic potentiation and membrane remodeling during synapse modification.  相似文献   

Platforms for collective action in multiple-use common-pool resources     

Nathalie A. Steins  Victoria M. Edwards 《Agriculture and Human Values》1999,16(3):241-255

Collective action processes in complex, multiple-use common-pool resources (CPRs) have only recently become a focus of study. When CPRs evolve into more complex systems, resource use by separate user groups becomes increasingly interdependent. This implies, amongst others, that the institutional framework governing resource use has to be re-negotiated to avoid adverse impacts associated with the increased access of any new stakeholders, such as overexploitation, alienation of traditional users, and inter-user conflicts. The establishment of platforms for resource use negotiation is a way of dealing with complex natural resource management problems. Platforms arise when stakeholders perceive the same resource management problem, realize their interdependence in solving it, and come together to agree on action strategies for solving the problem (Röling, 1994). This article sets the scene for a discussion in this Special Issue about the potential of nested platforms for resource use negotiation in facilitating collective action in the management of complex, multiple-use CPRs. The article has five objectives. First, we define collective action in the context of this paper. Second, we discuss the importance of collective action in multiple-use CPRs. Third, we introduce the concept of platforms to coordinate collective action by multiple users. Fourth, we address some issues that emerge from evidence in the field regarding the role and potential of nested platforms for managing complex CPRs. Finally, we raise five discussion statements. These will form the basis for the collection of articles in this special issue.  相似文献   

Defective phagocytosis of isolated rod outer segments by RCS rat retinal pigment epithelium in culture   总被引：5，自引：0，他引：5  

R B Edwards  R B Szamier 《Science (New York, N.Y.)》1977,197(4307):1001-1003

Retinal pigment epithelium cultured from normal rats phagocytizes large amounts of rod outer segment fragments isolated from normal rats and from RCS rats with inherited retinal degeneration. Cultured RCS rat pigment epithelium rarely ingests outer segment material, although the cells extend cellular processes around fragments of either type. Both normal and RCS pigment epithelium phagocytize polystyrene spheres. This demonstrates that RCS rat pigment epithelial cells contain a defect in the mechanism for phagocytizing outer segments.  相似文献   

Calcareous septa formed in snail shells by larvae of snail-killing flies     

L V Knutson  C O Berg  L J Edwards  A D Bratt  B A Foote 《Science (New York, N.Y.)》1967,156(774):522-523

Larvae of 13 species of Pherbellia and Colobaea that feed in exposed aquatic snails uitilize a product of the Malpighian tubules before they pupate to form a plate-like structure within the shell or to reinforce the anterior end of the puparium. The substance is partly calcium carbonate, and carbonic anhydrase may be involved in its production.  相似文献   

THE IDENTITY OF STREPTOCOCCI OF ANIMAL ORIGIN WITH CERTAIN STRAINS OF STR. EPIDEMICUS     

Edwards PR  Dimock WW 《Science (New York, N.Y.)》1932,76(1961):107-108

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Use of variations in natural nitrogen isotope abundance for environmental studies: a questionable approach   总被引：2，自引：0，他引：2  

R D Hauck  W V Bartholomew  J M Bremmer  F E Broadbent  H H Cheng  A P Edwards  D R Keeney  J O Legg  S R Olsen  L K Porter  D H Kohl  G B Shearer  B Commoner 《Science (New York, N.Y.)》1972,177(47):453-456

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