Assumptions and Terminology

Abstract

The concept of population structure of phytocoenoses is based on the finding that in the hierarchic structure of the plant kingdom populations hold a particular position since they lie “at the intersection” of the genetic and spatial levels of the biological organization. This concept is supported by the following findings: (a) populations of the same species in different phytocoenoses exhibit different dynamics and structure (Zarzycki 1964, 1968, Wilkoń-Michalska 1976, 1985, White 1985, Symonides 1985, Falińska 1979, 1985, 1986 b, c, 1989, a, b, Zhukova and Ermakova 1985, Vorontzova and Zaugolnova 1985); (b) individual variation within populations may be the result of modification by the environment, or it may be also of ecotype nature (McMillan 1964, Antonovics and Levin 1980, Solbrig 1980); (c) the density and distribution of individuals of various species in the biochore of a phytocoenosis are not a mirror image of the soil conditions, and do not always indicate the influence of competition; (d) no species occupies the entire territory which it could take into possession on account of the soil and climate, its tendencies to propagation clash with those of other species capable of existing in the same ecological conditions (Whittaker 1975); (e) the final species composition under specific conditions is determined by the interaction of populations of various species known as “phytocoenotic selection” (Rabotnov 1985).