The studies in the Ogawa Forest Reserve (OPR) were initiated by a group of plant ecologists and gradually expanded into a comprehensive project covering various aspects of biology, soil science, and silviculture. The project was integrated as part of the Forest Ecosystem Team under the BIO-COSMOS Program funded by the Ministry of Agriculture, Forestry and Fisheries. As the coordinators of the Forest Ecosystem Team, we are pleased that reports of the long-term studies carried out in the OFR are being published in this first volume on Japanese ecosystems in the Ecological Studies series. Scientists and researchers have made numerous contributions to the field of forest ecology during more than 10 years of studies in the OFR. Two reasons can be cited for the success of the project: scientists from various disciplines concen trated on a single target forest ecosystem, and the research continued over a rela tively long term. It is now recognized that ecological processes include compli cated mechanisms supported by interactions among organisms and large temporal variations. The researchers in the OFR project were motivated by their interest in the history of ecosystems and the interactions of diverse creatures in the forest.

The Ogawa Forest Reserve (OFR) is a species-rich, temperate, deciduous, old-growth forest in central Japan in which the ecology of the tree community has been intensively investigated since 1987. Detailed demographic data on the main tree species, covering the entire tree life cycle, were collected to elucidate the mechanisms by which community structure, organization, and species diversity are maintained. Included here is the work of more than 40 scientists in such diverse fields as botany, ecology, pedology, silviculture, mammal ecology, entomology, and ornithology, who have studied the same forest at the same time. This volume introduces the main areas of research under the OFR project and discusses the implications of the results on environmental issues. Integrated studies of this type are essential to clarify how species diversity is maintained, currently a central focus in ecology.