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2515042 
Journal Article 
The concepts of emergent and collective properties in individual-based models - Summary and outlook of the Bornhoved case studies 
Reuter, H; Holker, F; Middelhoff, U; Jopp, F; Eschenbach, C; Breckling, B 
2005 
Yes 
Ecological Modelling
ISSN: 0304-3800 
ELSEVIER 
AMSTERDAM 
186 
4 
489-501 
WOS:000231590800008 
Ecology requires the conceptual and technical ability to analyse complex and dynamic systems consisting of a high and variable number of components and relations. These components are part of a variable interaction structure in a spatially heterogeneous context. The components of ecological interaction networks can give rise to self-organised, and scale-dependent interaction patterns and processes, which are the underlying causes of the overall ecological systems states.



The individual-based modelling approach provides a widely applicable simulation framework based on a 'hierarchy theory' view of ecological systems.



Here, we summarise and generalise the theoretical implications of the modelling studies presented in this volume in the field of terrestrial and aquatic, animal and plant ecology. The case studies cover a representative profile of processes related to ecological applications, such as food web interactions, population dynamics, dispersal, energy physiology, nutrient allocation and mutual impact of morphological and physiological development. The generic approach applied in this context allows a hierarchical representation of ecological systems and their components. Model results are obtained as self-organised structural relation networks and as aggregated quantitative states. In order to address different model characteristics we distinguish collective and emergent properties. Collective properties are those that are attributed equally to different organisation levels of the system. Emergent properties result from the activities of lower level entities on a higher organisation level, while not being present on the lower level. They can be subdivided into aggregational and connective properties. Emergent properties that are aggregational are those which emerge as a result of an aggregation procedure by an observer on the higher level which does not make sense or is not applicable on lower levels. Emergent properties that are connective, however, are based on an interaction network of lower level entities, which brings about the specific system characteristic.



This classification of model results will allow to generalise the achievements and potential of the individual-based modelling approach in ecology. (c) 2005 Elsevier B.V. All rights reserved. 
emergent properties; collective properties; self-organisation; ecological complexity; individual-based model; Bornhoved; ground arthropods; dispersal; energy budget; community interaction; rodent cycles; plant growth; root development