25. Systemwissenschaftliches Kolloquium
Das Kolloquium findet nur im Wintersemester jeweils mittwochs von 16:15 bis 18:00 Uhr im Institut für Umweltsystemforschung, Barbarastr. 22c, Raum 93/E07 statt.
Prof. Dr. Jean-Christophe Poggiale, Mediterranean Institute of Oceanography, Aix-Marseille University (FRA):
Time scales in ecological modelling: theory and applications.
Dr. Frédéric Barraquand, LabEx COTE, University of Bordeaux (FRA)
Do interactions between species truly matter for understanding community dynamics?
Prof. Dr. Frank Wätzold, Lehrstuhl Volkswirtschaftslehre insbes. Umweltökonomie, BTU Cottbus:
A modelling procedure and a decision support system to design ecologically effective and cost-effective conservation payments in grassland.
Prof. Uwe Latacz-Lohmann, Department of Agricultural Economics, University of Kiel:
Assessing farmers' preferences for the green architecture of the Common Agricultural Policy.
Dr. Tad Dallas, Centre for Ecological Change, University of Helsinki (FIN):
Stochasticity influences species coexistence, spatial distribution, and invasion dynamics.
Prof. Dr. Peter Feindt, Albrecht Daniel Thaer Institute of Agricultural and Horticultural Sciences, Humboldt-Universität zu Berlin:
A policy design perspective on the Common Agricultural Policy.
Dr. Sven Lautenbach, Geographisches Institut, Abt. Geoinformatik, Universität Heidelberg:
Trade-offs of land use decisions.
Dr. Karlijn van den Broek, Alfred-Weber-Institut für Wirtschaftswissenschaften, Universität Heidelberg:
Mental models of complex dynamic systems: The case of Lake Victoria.
Prof. Dr. Maja Schlüter, Stockholm Resilience Center (SWE):
A complexity perspective for the study of human-environment systems.
Dr. Egbert van Nes, Department of Environmental Sciences, University of Wageningen (NED):
Critical transitions in ecology - an overview.
Prof. Dr. Felix Müller, Institut für Natur- und Ressourcenschutz, Abt. Ökosystem-Management, Universität Kiel:
Ecosystem valuation strategies at different scales.
Kurzfassung der Vorträge
Prof. Dr. Jean-Christophe Poggiale, Mediterranean Institute of Oceanography, Aix-Marseille University (FRA)
Time scales in ecological modelling: theory and applications
In a first step, some problems focusing on the choice of the formulations of the biological processes involved in ecosystem models are discussed. When possible, providing explicit relations between individual properties and population or community dynamics allows to build model formulations on a mechanistic basis. We discuss some examples where this approach is useful for understanding the community dynamics. The functional response in predator - prey systems is an example of ecological process involving several levels of organization and time scales. Its mathematical formulation should depend on the applications of the model: which spatial scales are considered? Is the environment homogeneous or heterogeneous? These questions should shape the choice of the formulations used in models. Moreover, the data used to develop a model are often acquired in conditions which are different than those of the applications. For instance, some formulations are based on data obtained in laboratory experiments, while the models are used to describe natural environments. Scaling up methods, which provide explicit links between different organization levels or between several temporal/spatial scales, are then useful to build formulations adapted for models used in the natural environment. Several applications to marine systems modelling are then presented.
Dr. Frédéric Barraquand, LabEx COTE, University of Bordeaux
Do interactions between species truly matter for understanding community dynamics?
Interactions between species are a cornerstone of ecology, and many dynamical models now incorporate these interactions between and within trophic levels. Including interspecific interactions in population dynamics models has even been advocated as the new paradigm for applied ecology (e.g., fisheries management). Yet, to what extent interactions between species are truly pivotal in determining the dynamics of co-occurring species (communities) is unclear and the empirical evidence is currently a mixed bag.
In this talk, I will first attempt to define what we mean by interactions from a population dynamics perspective, which is often less easy than it may appear. I will then link a unified statistical approach to estimating interactions (multivariate time series models, also used in other disciplines like econometrics and neurosciences) to basic models of ecological communities. We will see that interspecific interactions are often estimated as weak, especially when contrasted to intraspecific interactions, that are often much more prominent in statistical models and dominating dynamical behaviour. This is likely to be so for species-rich competitive communities because weak interspecific interactions are required for persistence, but I will also highlight ways in which interactions between different species can "vanish" when we scale up from individuals to populations or be obfuscated by interactions within species, for instance due to stage structure (differentiated juveniles and adults). In this context where unstructured population models may have quite a few limitations, I will finally highlight the need for a demographic approach to the population dynamics of interacting species, in order to better infer parameters and predict trajectories.
Prof. Dr. Frank Wätzold, Lehrstuhl Volkswirtschaftslehre insbes. Umweltökonomie, BTU Cottbus
A modelling procedure and a decision support system to design ecologically effective and cost-effective conservation payments in grassland
Agri-environment schemes (AES), under which farmers are compensated for forms of land use that benefit wildlife, help to protect the environment from the harmful effects of agriculture across Europe. With limited conservation budgets, how to design more cost-effective schemes has become a major focus for research. This study presents a new modelling tool to design cost-effective schemes to conserve grassland biodiversity, defining a cost-effective AES as one that “either maximises the level of conservation of endangered species and habitats for a given budget or achieves the desired conservation aims for a minimum budget”. The model covers a range of endangered grassland species (including 13 bird species and 14 butterfly species) and seven different types of grassland. It also accounts for the effects of 475 types of mowing regimes, grazing regimes and combinations of both. Importantly, the procedure accounts for differences in the cost and effect of these measures depending on where (spatial variation) and when they are applied (temporal variation). The model was applied to the German Federal State of Saxony, and identified major cost improvements. The procedure suggested that all species and grassland types that are conserved by the existing scheme (which costs €11 127 000 to implement) could be conserved for €7 974 000 — resulting in a €3 153 000 saving. What’s more, the new scheme also improved conservation, with moderate improvements in protection for birds and significant improvements for butterflies. The model provides the basis for a decision support software, DSS-Ecopay, to design ecologically effective and cost-effective AES in grasslands. The software is available free of charge at http://www.inf.fu-berlin.de/DSS-Ecopay/ecopay_main_eng.html.
Prof. Uwe Latacz-Lohmann, Department of Agricultural Economics, University of Kiel
Assessing farmers' preferences for the green architecture of the Common Agricultural Policy
This paper assesses the preferences of German farmers for the future green architecture of the EU’s Common Agricultural Policy (CAP). The analysis is based upon a Discrete Choice Experiment (DCE) with 440 farmers from across Germany. The respondents were recruited through articles in the farming press. In the online survey, respondents were confronted with the choice among three alternative policy packages and an opt-out option. The policy packages were characterised by varying levels of environmental and animal welfare requirements as well as different values of direct income support payments. The opt-out option effectively meant a discontinuation of the key elements of the CAP, including the direct payments, while maintaining only minimum environmental and animal welfare standards. The choice data were analysed using both a conditional logit and a latent class model – the latter to reveal preference heterogeneity among respondents. Approximately two thirds of the respondents voted for a continuation of the direct payments scheme. A subgroup of these respondents (46% of all respondents) was willing, in principle, to accept higher environmental and animal welfare standards in return. Twenty percent of the respondents wished continuation of the direct payments scheme without reciprocity. The majority of the interviewees were against a market safety net of low-level intervention prices. One third of the interviewed farmers voted for a discontinuation of the CAP in its current form.
Dr. Tad Dallas, Centre for Ecological Change, University of Helsinki (FIN)
Stochasticity influences species coexistence, spatial distribution, and invasion dynamics
Species competition and spatial spread is influenced by many chance events. For instance, smaller populations are more likely to go extinct as a result of probabilistic birth and death processes. In this work, I examine the role of these stochastic processes -- both demographic and environmentally driven -- in determining the outcome of species competition in a single habitat, in a simple two-patch system, and across a larger spatial landscape. Using a combination of theory and experimental microcosms of flour beetles, I examine the role stochasticity plays in regulating populations and communities. Apart from simply increasing the uncertainty in estimates of ecological processes, I find that different forms of stochasticity affect ecological systems differently, with implications to species competitive outcomes from small spatial scales (single habitat patch) to much larger ones (entire landscapes).
Prof. Dr. Peter Feindt, Albrecht Daniel Thaer Institute of Agricultural and Horticultural Sciences, Humboldt-Universität zu Berlin
A policy design perspective on the Common Agricultural Policy
Dr. Sven Lautenbach, Geographisches Institut, Abt. Geoinformatik, Universität Heidelberg
Trade-offs of land use decisions
Dr. Karlijn van den Broek, Alfred-Weber-Institut für Wirtschaftswissenschaften, Universität Heidelberg
Mental models of complex dynamic systems: The case of Lake Victoria
Mental models comprise people’s understanding of complex systems. These perceptions often vary widely across different people, while they greatly influence daily decision-making. We have investigated mental models at Lake Victoria, where the Nile perch stock has been declining in the past decades, due to a complex interplay of ecological, social and institutions factors. A novel approach for mental model elicitation was developed and validated at Lake Victoria to capture fishers’ perceptions of the dynamic processes of the Nile perch stock. This presentation will report on the use of this method and its validation in comparison to interview data. Moreover, I will show the mental models of the fishers and relate the complexity and focus of the mental models to individual differences across the fishers. The findings of this study will be discussed in relation to mental models of other conservation challenges as well as how these findings can inform policy that aims to address such issues.
Prof. Dr. Maja Schlüter, Stockholm Resilience Center (SWE)
A complexity perspective for the study of human-environment systems
Dr. Egbert van Nes, Department of Environmental Sciences, University of Wageningen (NED)
Critical transitions in ecology - an overview
In this talk I will introduce the concepts of critical transitions and resilience in natural systems. My main example is the ecosystem of shallow lakes, where we found evidence that these can have two alternative states: the clear water state dominated by aquatic vegetation and the turbid water state dominated by algae. I will argue that the positive self-enforcing feedback of vegetation is crucial for the existence of the alternative states. For lake management it is important that we can expect that once a lake has become turbid it is hard to restore it due to hysteresis. I will also point to various other examples of bistable ecosystems. Resilience is a relevant measure of the stability of systems with alternative stable states. However resilience is notoriously difficult to measure in practice. Recently we have suggested that critical slowing down before a critical transition could be used as measure in practice. I will first explain how we can measure this using experimental perturbations. Alternatively, we can use increased variance and increased autocorrelation in stochastic time series to probe that a system slows down. I will discuss when we can expect that these resilience indicators will work and when not.
Prof. Dr. Felix Müller, Institut für Natur- und Ressourcenschutz, Abt. Ökosystem-Management, Universität Kiel
Ecosystem valuation strategies at different scales
In order to develop tools for ecosystem-based environmental decision making processes, two linked holistic strategies have been constructed, (1) an evaluation concept of ecosystem integrity, based on ecosystem theories and orientor development, and (2) an assessment system related to the potentials of ecosystems for the supply of ecosystem service bundles. Both approaches are focusing on the ecosystem scale, but they are also applied to landscapes, coastal areas and seascapes. The recent research spaces are concentrated in the terrestrial regions of Northern Germany and the Baltic Sea hydro-system.
During the presentation, the basic theoretical foundations of the approach will be discussed, qualitative and quantitative methods will be described, referring to the GIS-coupled analyses, remote sensing procedures, matrix valuation sheets, statistical interpretations, BBN networks and model applications. The applications of these approaches will be presented on the basis of Northern German data sets. Finally, an illumination of the causes of uncertainties will lead to a critical discussion of the applicability of the concepts.