Next generation ecological modelling, concepts, and theory:
structural realism, emergence, and predictions

A Special Issue in “Ecological Modelling” dedicated to
the 70th birthday of Donald DeAngelis

Guest editors: Volker Grimm (UFZ) and Uta Berger (TU Dresden)

Developing ecological theory is not an academic exercise. In a world facing unprecedented rates of change in climate, land use, and global interactions, understanding the functioning of ecological systems and forecasting their responses have become critical for ensuring ecosystem services. However, developing models for each system and question of interest is infeasible. We need reliable general concepts and theories that can guide the sustainable management of natural resources. The attempt to devise such theories exclusively via simple strategic models, which ignored complexity and imposed system behaviour, did not lead to applicable results. Early attempts to embrace complexity in systems simulation models in the 1960s failed too, but the last decade has seen major advances in developing predictive and models that take into account spatial relationships, variability of habitats and resources, individual behaviour, physiology, bioenergetics, stoichiometry, and that cover multiple levels of organisation and scales from the local subpopulation to continents and the globe.

So far, these advances have only partially been summarized and integrated, and there have been hardly any attempt to synthesize general theory based on the particular findings and achievements. This special issue is trying to fill this gap. We invite contributions addressing concepts, modelling, or theories that are related to the following three key aspects:

• Structural realism. Models have to simplify. Making a model matching observations always has to involve some tweaking of model structure and parameters. To what degree, then, does the model still capture the organization of the real system being essential for understanding its functioning? We need indicators of structural realism and a new culture of communicating them.
• Emergence. Imposing empirically observed parameters and functional relationship limits the scope of a model to the conditions under which these parameters and relationships were observed. To allow models making predictions for a wider range of conditions, key processes and behaviour should emerge in the model from lower-level processes, for example physiology or fitness seeking. We are searching for approaches that link two or more hierarchical levels of ecosystems demonstrating the interconnections between mechanisms, structures and overall constraints.
• Predictions. Model output often is referred to as ‘prediction’ even if is the result of heavy calibration. A clearer conceptual distinction of calibration, extrapolation, forecasting, and prediction is needed, the latter referring to responses to new conditions, for which no response data exist. Key questions are, e.g., (a) what ecologists should try to predict: exact quantities or broad patterns characterizing real systems? or (b) how can we assess the quality of model predictions?

We invite contributions, in particular reviews as well as opinion or methodological articles, which address one or more of the issues introduced above. To acknowledge the spirit of the work of Donald DeAngelis, to whom this special issue will be dedicated as a celebration of his 70th birthday, we make no restrictions regarding model type or type of ecological system addressed. We are keen to bring together developers of simple and complex models, of terrestrial, freshwater, and marine modellers, and mechanistic and statistical modelling. Case studies are welcome, but only if they are used to demonstrate of more general concept, modelling approach, or theory.

Timeline:
31. July 2014 – deadline submission abstract containing the key messages of the manuscript. Based on this we would like to check potential contributors and topics, and further develop the concept (overall scheme, sequence of subsections) of the special issue in order to strengthen its programmatic power rather than producing a Salmagundi Magazine. We will compile a 1-2 page overview about all potential contribution and spread it among the authors in order to facilitate crosslinks.

31. October 2014 - deadline for submission the full manuscript.

We aim finishing the external reviewer process in January 2015 in order to publish the special issue in the first half of 2015.

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