The journal is concerned with the use of mathematical models and systems analysis for the description of ecosystems and for the control of environmental pollution and management of resources. It combines mathematical modelling, systems analysis, thermodynamics and computer techniques with ecology and management of the environment and its natural resources. When man intrudes he inevitably disturbs the delicate balance of organisms, substances and their activity, that Nature has evolved. Ecosystems can adapt to man's violent activities, but only up to a certain point. The impact on ecosystems can only be described quantitatively by the application of ecological models and systems ecology, and their reactions to perturbations can only be understood by the use of ecosystem theory. The fields of ecological modelling, systems ecology and ecosystem theory are consequently the basis of the philosophy behind the journal.A reduced personal subscription rate is available to all members of the International Society for Ecological Modelling (ISEM), http://ecomod.tamu.edu/~ecomod/isemna.html. Please apply to the Publisher for more information. EcoSummit 2000 'Understanding and solving environmental problems in the 21st century' takes place 18-22 June 2000 in Halifax, Canada. The meeting will incorporate the 2000 ISEM International Meeting, the 2000 IEES Annual Meeting, the AEHMS 2000 Business Meeting and the inaugural meeting of the International Environmental Modeling & Software Society (IEMSS) For full details see http://www.elsevier.com/locate/ecosummit