The beginnings of ecosystem research in Báb are closely linked to the International Biological programme (IBP). The forest in Báb (66 ha) was selected for the IBP as an example of a deciduous broad-leaved forest on loess, litte changed by man. The research began in 1967, when the permanent research plot (PRP) of size 1 ha was selected and permanently marked. The main aim was to obtain knowledge of the mechanisms of production processes, identifia- tion of principles the ecosystem functioning and interactions between its components. In the fist research phase (fist two years), the fundamental issues were in focus: to characterize the natural environment and forest ecosystem, to perform inventory of living organisms. In the second phase the research aimed to produce syntheses in the following areas: micro-meteorology and micro-climate, soils, soil microbiology, ecophysiological processes of plants (photo- synthesis, water relations, mineral nutrition), primary productivity, nutrient cycles, water circulation, secondary productivity, mathematical programming and statistical methods, synthesis of the forest biome. More than 60 researchers (including PhD and diploma students) and around 30 technicians from nearly 20 research institutions of Slovak Academy of Sciences, universities, forestry, agricultural and other research bodies performed a comprehensive ecosystem research in the PRP Báb and surrounding forest. The Research Project Báb (IBP) was a scientifi experi- ment with a new, integrated approach to address complex environmental issues. It harmonised purposefully vari- ous scientifi filds, but also enforced quantitative and experimental approach in many traditional disciplines. The ecosystem research in Báb improved knowledge of the functioning of the ecosystem of temperate deciduous forest of Danube Lowland, contributed to the development of ecology as science and its environmental sub-disciplines (e.g. quantitative ecology, production ecology, ecophysiology, functional ecology, population ecology) in Slovakia.