TY - GEN
A1 - Sanner, Helge
T1 - Imperfect goods and labor markets, and the union wage gap
N2 - Existing theoretical literature fails to explain satisfactorily the differences between the pay of workers that are covered by collective agreements and others who are not. This study aims at providing a model framework which is amenable for an analysis of this issue. Our general-equilibrium approach integrates a dual labor market and a two-sector product market. The results suggest that the so-called 'union wage gap' is largely determined by the degree of centralization of the bargains, and, to a somewhat lesser extent, by the expenditure share of the unionized sector's goods.
KW - Verhandlungstheorie
KW - Monopolistische Konkurrenz
KW - Gewerkschaften
KW - union wage premium
KW - comparative analysis
KW - wage differentials
KW - dual labor market
KW - monopolistic competition
Y1 - 2005
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-6511
ER -
TY - GEN
A1 - Siepmann, Gerda
A1 - Salzberg-Ludwig, Karin
T1 - Research project to the subject
BT - strain and stress in school ; examined on handicapped and non-handicapped school-age children
Y1 - 2004
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-6502
ER -
TY - GEN
A1 - Heinken, Thilo
A1 - Raudnitschka, Dorit
T1 - Do wild ungulates contribute to the dispersal of vascular plants in central European forests by epizoochory?
BT - A case study in NE Germany
BT - Eine Fallstudie aus Nordostdeutschland
N2 - The external dispersal ("epizoochory") of vascular plant diaspores (seeds and fruits) by roe deer and wild boar, i.e. the most common wild large mammals with a large home range in central Europe, was investigated in a 6.5-km² forest area in NE Germany dominated by mesic deciduous forests. The study involved brushing out the diaspores from the coats and hooves of 25 shot roe deer and nine wild boar. The results were compared with the forest vegetation of the study area. Whilst wild boar transported large amounts of various diaspores in the coat, the significance of roe deer for epizoochory was low due to their sleek fur and different behaviour compared to wild boar. Altogether, 55 vascular plant species were transported externally. Since only a limited number of seeds came from woodland habitats, the open landscape was at least as important as a source of attached seeds as the forest vegetation. Thus, most plant species occurring in the studied forest area, especially characteristic woodland herbs, showed no adaptations to epizoochorous dispersal, although being very abundant in the herb layer. We conclude that hoofed game play a particular role concerning the dispersal of ruderal and grassland species in the agricultural landscape of central Europe. However, the actual spread of some herb species in forests of northern Germany, e.g. Agrostis capillaris, Brachypodium sylvaticum, Deschampsia flexuosa, Galium aparine and Urtica dioica, may be mainly facilitated by wild ungulates. Though dispersal by large mammals is an important mechanism for long-distance dispersal of plants in general, our results suggest that most of the characteristic herb species of mesic deciduous forests have only low epizoochorous dispersal potentials. The implications for nature conservation and silviculture are discussed.
N2 - Die Ausbreitung von Gefäßpflanzen-Diasporen (Samen und Früchte) durch äußerliche Anhaftung ("Epizoochorie") an Rehen und Wildschweinen, den beiden häufigsten Schalenwild-Arten in Mitteleuropa, wurde im 6,5 km² großen Forst Brieselang bei Berlin (Bundesland Brandenburg) untersucht, in dem mesophile Laubwälder vorherrschen. Dazu wurden die Felle und Hufe von 25 geschossenen Rehen und neun Wildschweinen ausgekämmt und die Diasporen anschließend bestimmt. Die Ergebnisse wurden mit der Waldvegetation verglichen. Während Wildschweine große Mengen verschiedener Diasporentypen transportierten, war die Bedeutung von Rehen für die Ausbreitung von Pflanzen auf Grund des glatten Fells und der im Vergleich zum Wildschwein unterschiedlichen Verhaltensweisen wesentlich geringer. Insgesamt wurden 55 Phanerogamenarten epizoochor transportiert. Da nur ein kleiner Teil der ausgebreiteten Pflanzen Waldhabitate bevorzugt, war das Offenland eine mindestens ebenso wichtige Quelle anhaftender Diasporen wie die Waldvegetation. Die meisten Waldpflanzenarten wurden nicht ausgebreitet; insbesondere solche Arten, die ausschließlich in Wäldern wachsen, wurden nicht nachgewiesen. Viele Pflanzenarten sind – vermutlich auf Grund ihrer Diasporenmorphologie – weitgehend vom Transport ausgeschlossen, obwohl sie sehr häufig in der Krautschicht des untersuchten Waldes vorkommen. Daher ist Schalenwild in der Agrarlandschaft Mitteleuropas vermutlich vor allem für die Ausbreitung von Ruderal-, Segetal- und Grünlandpflanzen von Bedeutung. Die Ausbreitung einiger Pflanzenarten der Krautschicht in norddeutschen Wäldern z.B. Agrostis capillaris, Brachypodium sylvaticum, Deschampsia flexuosa, Galium aparine und Urtica dioica, könnte jedoch wesentlich auf Schalenwild zurückgehen. Obwohl Großsäuger insgesamt ein wichtiger Vektor für die Fernausbreitung von Pflanzen sind, zeigt unsere Studie, dass die meisten charakteristischen Waldbodenpflanzen mesophiler Laubwälder kaum ausgebreitet werden, also nur ein geringes epizoochores Ausbreitungspotenzial aufweisen. Die Bedeutung der Ergebnisse für den Waldnaturschutz und den Waldbau wird diskutiert.
T2 - Trägt Schalenwild durch Epizoochorie zur Ausbreitung von Gefäßpflanzen in mitteleuropäischen Wäldern bei?
KW - Diasporenmorphologie
KW - Epizoochorie
KW - Brandenburg
KW - Reh
KW - Waldbodenpflanzen
KW - Wildschwein
KW - diaspore morphology
KW - epizoochory
KW - forest plant species
KW - NE Germany
KW - roe deer
KW - wild boar
Y1 - 2002
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-5850
ER -
TY - GEN
A1 - Heinken, Thilo
T1 - Migration of an annual myrmecochore
BT - a four year experiment with Melampyrum pratense L.
N2 - A seed sowing experiment was conducted in a mixed secondary woodland on acidic soils in NE Germany with Melampyrum pratense, an annual ant-dispersed forest herb which lacks a natural population in the study area, but is abundant in similar habitats. Each set of 300 seeds was sown within one square metre at three sites in 1997, and the development of the populations was recorded from 1998 onward. Additionally, seed fall patterns were studied in a natural population by means of adhesive cardboard. All trials resulted in the recruitment of populations, which survived and increased in both individual number and area, up to the year 2001. Thus, local distribution of Melampyrum pratense is dispersallimited. Total individual number increased from 105 to 3,390, and total population area from 2.07 to 109.04 m². Migration occurred in all directions. Mean migration rate was 0.91 m per year, and the highest migration rate was 6.48 m. No individual was recorded beyond 7.63 m from the centres of the sawn squares after three years, suggesting exclusive short-distance dispersal. As primary dispersal enables only distances of up to 0.25 m, ants are presumed to be the main dispersal vectors. Despite differences in individual number and colonization patterns, migration rates did not differ significantly between the populations, but were significantly higher in 2001 due to an increased population size. Colonization patterns were characterized by a rapid, negative exponential decrease of population density with increasing distance from the sown plot, suggesting a colonization by establishment of more or less isolated outposts of individuals and a subsequent gradual infill of the gaps between. My results resemble myrmecochorous dispersal distances in temperate woodlands, and migration rates and patterns across ecotones from ancient to recent deciduous forests. They may function as a colonization model of Melampyrum pratense after accidental long-distance dispersal.
KW - artificial introduction
KW - colonization
KW - dispersal
KW - myrmecochory
KW - NE Germany
KW - woodland herb
Y1 - 2004
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-5865
ER -
TY - GEN
A1 - Hoppert, Michael
A1 - Reimer, Rudolph
A1 - Kemmling, Anne
A1 - Schröder, Annekatrin
A1 - Günzl, Bettina
A1 - Heinken, Thilo
T1 - Structure and reactivity of a biological soil crust from a xeric sandy soil in Central Europe
N2 - The investigation was designed to explore the structure, composition and activity of a biological soil crust on an acidic, sandy soil from a temperate climate. The crust covers several hundreds of square meters on the hilltop of a large terminal moraine. The conjugate alga Zygogonium ericetorum forms the essential matrix for the crust, a dense web of algal filaments with interspersed lichens and mosses. The crust is composed of three layers, with an uppermost layer consisting nearly entirely of a dense algal mat. In lower layers, a parasitic fungus, penetrating the algal cells, is another important component of the crust community. In this soil crust, photosynthetic and respiratory activity is stabilized at low water activities.
KW - biological soil crust
KW - desiccation tolerance
KW - electron microscopy
KW - Fusarium oxysporum
KW - Zygogonium ericetorum
Y1 - 2004
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-5872
ER -
TY - GEN
A1 - Köchy, Martin
A1 - Wilson, Scott D.
T1 - Variation in nitrogen deposition and available soil nitrogen in a forest–grassland ecotone in Canada
N2 - Regional variation in nitrogen (N) deposition increases plant productivity and decreases species diversity, but landscape- or local-scale influences on N deposition are less well-known. Using ion-exchange resin, we measured variation of N deposition and soil N availability within Elk Island National Park in the ecotone between grassland and boreal forest in western Canada. The park receives regionally high amounts of atmospheric N deposition (22 kg ha⁻¹ yr⁻¹). N deposition was on average higher ton clayrich luvisols than on brunisols, and areas burned 1 – 15 years previously received more atmospheric N than unburned sites. We suggest that the effects of previous fires and soil type on deposition rate act through differences in canopy structure. The magnitude of these effects varied with the presence of ungulate grazers (bison, moose, elk) and vegetation type (forest, shrubland, grassland). Available soil N (ammonium and nitrate) was higher in burned than unburned sites in the absence of grazing, suggesting an effect of deposition. On grazed sites, differences between fire treatments were small, presumably because the removal of biomass by grazers reduced the effect of fire. Aspen invades native grassland in this region, and our results suggest that fire without grazing might reinforce the expansion of forest into grassland facilitated by N deposition.
KW - fire
KW - grazing
KW - vegetation type
KW - soil type
KW - shrubland
KW - forest invasion
KW - subboreal
KW - aspen parkland
KW - Canada
Y1 - 2004
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-5768
ER -
TY - GEN
A1 - Ginoux, Nicolas
T1 - Dirac operators on Lagrangian submanifolds
N2 - We study a natural Dirac operator on a Lagrangian submanifold of a Kähler manifold. We first show that its square coincides with the Hodge - de Rham Laplacian provided the complex structure identifies the Spin structures of the tangent and normal bundles of the submanifold. We then give extrinsic estimates for the eigenvalues of that operator and discuss some examples.
KW - Dirac operators
KW - Global Analysis
KW - Spectral Geometry
KW - Spin Geometry
KW - Lagrangian submanifolds
Y1 - 2004
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-5627
ER -