Systems Analysis and Simulation in Ecology, Volume I, is a book of ecology in transition from a ""soft"" science, synecology, to a ""hard"" science, systems ecology. It is an enthusiastic and optimistic statement about the fundamental adaptability of the scientific mechanism to newly appreciated truths of existence. It documents, in ecological science, a move away from the explanatory or cognitive criterion toward the predictive criterion, a hard one with the potential of leading ultimately to optimal design and control of ecosystems. The book is organized into three parts. Part I is an overview of some of the methods and rationales for ecological systems modeling for the purposes of simulation and systems analysis. It provides an elementary introduction to the use of analog and digital computers for simulation and a rationale for ecological model-building. Part II illustrates three different approaches to population modeling. These include a mathematical analysis of microbial (Chlorella, Selenastrum) dynamics in both continuous and batch cultures; and a bioenergetics study of the terrestrial isopod Armadillidium, utilizing concepts from control theory and the transfer function technique of classical dynamic analysis. Part III brings together a group of papers describing various aspects and philosophies of ecological simulation. These include common problems in ecosystem simulation and the question whether or not some of the newer methods of systems ecology might not be used in connection with some of the older data and observations of traditional synecology.