TY  - GEN
A1  - Ceulemans, Ruben
A1  - Gaedke, Ursula
A1  - Klauschies, Toni
A1  - Guill, Christian
T1  - The effects of functional diversity on biomass production, variability, and resilience of ecosystem functions in a tritrophic system
T2  - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe
N2  - Diverse communities can adjust their trait composition to altered environmental conditions, which may strongly influence their dynamics. Previous studies of trait-based models mainly considered only one or two trophic levels, whereas most natural system are at least tritrophic. Therefore, we investigated how the addition of trait variation to each trophic level influences population and community dynamics in a tritrophic model. Examining the phase relationships between species of adjacent trophic levels informs about the strength of top-down or bottom-up control in non-steadystate situations. Phase relationships within a trophic level highlight compensatory dynamical patterns between functionally different species, which are responsible for dampening the community temporal variability. Furthermore, even without trait variation, our tritrophic model always exhibits regions with two alternative states with either weak or strong nutrient exploitation, and correspondingly low or high biomass production at the top level. However, adding trait variation increased the basin of attraction of the high-production state, and decreased the likelihood of a critical transition from the high- to the lowproduction state with no apparent early warning signals. Hence, our study shows that trait variation enhances resource use efficiency, production, stability, and resilience of entire food webs.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 744 
KW  - early-warning signals
KW  - top-down control
KW  - community ecology
KW  - regime shifts
KW  - food webs
KW  - compensatory dynamics
KW  - consumer diversity
KW  - metabolic theory
KW  - rapid evolution
KW  - stable states
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-435439
SN  - 1866-8372
IS  - 744
ER  - 
TY  - RPRT
A1  - Petersen, Hans-Georg
T1  - Steuern in Fragilen Staaten
BT  - Empfehlungen für die Entwicklungszusammenarbeit
T2  - Finanzwissenschaftliche Diskussionsbeiträge
N2  - Fragile states are characterized by institutions which do not have the political will or ability to reduce poverty in the interests of their citizen, to establish basic social security, to promote a successful development process, and to guarantee security and human rights. The regional disintegration processes after the period of imperialism and the fall of the iron curtain have created many new states, which still are politically unstable and unable for a sustainable development. In the literature such states are describes as "weak", "failing or failed", "collapsed", "conflict or post-conflict" - dependant on the extent of the particular state failure. Several indicators try to describe such states and partly allow for projections of the future development. Then the role of taxation is discussed in detail before recommendations for the development cooperation are presented. Obviously taxation plays a key role for the democratization process in fragile states.
T3  - Finanzwissenschaftliche Diskussionsbeiträge - 61 
KW  - fragile state
KW  - state theory
KW  - stable states
KW  - fragility index
KW  - taxation
KW  - shadow economy
KW  - tax administration
KW  - development cooperation
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-48465
SN  - 1864-1431
SN  - 0948-7549
IS  - 61
ER  -