The interactions of species in ecological communities, such as phytophagy, predation, competition, and mutualism, determine the diverse relationships between plants, animals, and microorganisms in their habitats. The authors address the effects of these interactions on the number of species and individuals, as well as the regulatory processes in biocoenoses, making it a central and highly relevant topic in ecology. Foundations and recent research findings are presented clearly using many case studies and numerous detailed illustrations and graphics. Key statements highlighted in the text, summaries at the end of chapters, and a comprehensive glossary serve as effective learning aids. The second updated and expanded edition takes into account the latest scientific developments. It offers an understandable and clear presentation of complex interrelationships.