The manual addresses the main problems of phytocenology: the relationship between autotrophic organisms and their consorts (parasites, symbionts, animals), various forms of plant influence on each other (competition, allelopathy, etc.), composition, structure, seasonal and multi-year variability, change of phytocenoses. The book summarizes the basic data characterizing the current state of science. The main focus, as in previous editions, is on addressing the biological problems of studying plant communities.