Typification of Plant Populations on the Basis of Their Ontogenetic Spectra

Knowledge of the age structure of plant populations is required to assess their current state and forecast their population dynamics and the dynamics of related phytocoenosis components, since the environment load differs for different age groups. The age-based plant ontogenesis periodization scheme proposed by T.A. Rabotnov and A.A. Uranov distinguishes about a dozen main ontogenetic states. Accordingly, each population sample represents an ordered series of frequencies of these states (the so-called ontogenetic spectrum). However, roles of some ontogenetic states in the classification of coenopopulations are interpreted ambiguously, while attempts to estimate profiles of ontogenetic spectra encounter statistical problems. It is proposed to standardize approaches to the typification of the age structure and indices of plant coenopopulations by reducing the ontogenetic spectrum to a standard scale of ontogenetic periods: pregenerative, generative, and postgenerative. In view of this, the following aspects are examined: classical coenopopulation types (invasive, regressive, invasive–regressive, and normal), different variants of normal coenopopulations, indices reflecting the age structure, and potential irregularity of the period scale.