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  • 1995-1999  (4)
  • 1945-1949
  • conservation  (2)
  • heterogeneous agents  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Plant communities and conservation of Botrychium-rich grasslands in the Bitcherland (Northern Vosges Biosphere Reserve, France) (1999)
    Springer
    Biodiversity and conservation 8 (1999), S. 1519-1532 
    Details
    ISSN: 1572-9710
    Keywords: Botrychium ; Pteridophyte ; grassland ; conservation ; plant community
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two species of Botrychium are present in the Bitcherland grasslands, B. lunaria and B. matricariifolium, and both are protected in this territory. They occur in five different continental grassland communities, (i) a dune grassland (Diantho-Armerietum), (ii) a mesotrophic sandy grassland (Viscario-Avenetum), composed of three sub-units, therophitic ( V.A. airetosum), meso-eutrophic (V.A. saxifragetosum) and acidic (V.A. violetosum caninae), and (iii) an oligotrophic sandy grassland (Aveno-Genistetum). Both species of Botrychium appear in the three sub-units of Viscario-Avenetum, but only one in Diantho-Armerietum (B. matricariifolium) and in Aveno-Genistetum (B. lunaria). These Botrychium species are present in quite similar habitats in other lowland areas in Central Europe. The conservation of these threatened species, sensitive to plant competition, requires the maintenance or restoration of extensive agricultural management with late cutting and no fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008988709046
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Phytosociology and conservation of Carex hordeistichos Vill. in the Lorraine region (France) (1999)
    Springer
    Biodiversity and conservation 8 (1999), S. 1435-1445 
    Details
    ISSN: 1572-9710
    Keywords: clay ; conservation ; pasture ; phytosociology ; ruderal plant ; trampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carex hordeistichos is a peri-Mediterranean species, which is rare over all its distribution range. In Lorraine (France), where the field investigations were conducted, as in other Western European areas, it is present only in secondary habitats, constituted of heavily trampled wet pastures and vehicle tracks on clayed soils. All plant communities with Carex hordeistichos described from Western European areas can be linked to the Carici hordeistichi-Trifolietum fragiferi association, classified in the Agropyro-Rumicion wet pasture alliance. The conservation of this threatened ruderal plant requires the maintenance of a high disturbance level through grazing, trampling and soil packing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008956506479
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Heterogeneity and the Voluntary Provision of Public Goods (1999)
    Springer
    Experimental economics 2 (1999), S. 5-30 
    Details
    ISSN: 1573-6938
    Keywords: public goods ; voluntary provision ; heterogeneous agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract We investigate the effects of heterogeneity and incomplete information on aggregate contributions to a public good using the voluntary contribution mechanism. The non-linear laboratory environment has three-person groups as partners under varying conditions of information and communication. Bergstrom, Blum and Varian predict that increasing heterogeneity will have no effect on aggregate contributions in a no-communication environment. Ledyard conjectures a positive effect of incomplete information, a negative effect of heterogeneity, and a positive interaction of heterogeneity and incomplete information. We find that incomplete information has a small but significant negative effect. Heterogeneity has a positive effect on aggregate contributions, but its effects interact unexpectedly with communication. In a no-communication environment, heterogeneity in two dimensions (endowment and preferences) increases contributions substantially while heterogeneity in a single dimension (endowment or preferences) has little effect. In the communication environment we find the reverse. We also find a positive interaction between heterogeneity and incomplete information. Thus we reject the Bergstrom, Blume and Varian invariance result and provide mixed evidence on Ledyard's conjectures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009984414401
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Heterogeneity and the voluntary provision of public goods (1999)
    Springer
    Experimental economics 2 (1999), S. 5-30 
    Details
    ISSN: 1573-6938
    Keywords: public goods ; voluntary provision ; heterogeneous agents ; H41 ; C92
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract We investigate the effects of heterogeneity and incomplete information on aggregate contributions to a public good using the voluntary contribution mechanism. The non-linear laboratory environment has three-person groups as partners under varying conditions of information and communication. Bergstrom, Blum and Varian predict that increasing heterogeneity will have no effect on aggregate contributions in a no-communication environment. Ledyard conjectures a positive effect of incomplete information, a negative effect of heterogeneity, and a positive interaction of heterogeneity and incomplete information. We find that incomplete information has a small but significantnegative effect. Heterogeneity has apositive effect on aggregate contributions, but its effects interact unexpectedly with communication. In a no-communication environment, heterogeneity in two dimensions (endowment and preferences) increases contributions substantially while heterogeneity in a single dimension (endowment or preferences) has little effect. In the communication environment we find the reverse. We also find a positive interaction between heterogeneity and incomplete information. Thus we reject the Bergstrom, Blume and Varian invariance result and provide mixed evidence on Ledyard's conjectures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01669132
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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