Plant population processes in the course of forest succession in abandoned meadows. II. Demography of succession promotors

Abstract

The studies on populations in the course of forest succession in abandoned meadows (15 ha) were conducted for 15 years (1974-1988). It was found that the population size of species which took part in the successional process either changed directionally, i.e. developmental phases of populations conformed to the succession stages, or fluctuated, when no direct relationship between both was determined. Three types of population dynamics were distinguished: 1) developmental cycle (increase, decrease and equilibrium in population size) lasted as long as forest comeback; 2) developmental cycle accompanied one successional phase; 3) species appeared in cycles, as a series of populations in the course of long-term succession. Following species groups were distinguished regarding their role in the vegetation transformation in unmown meadows: 1) long-term promotors, present throughout succession and affecting both, changes in meadow vegetation, and initiation of tall-herb and brushwood communities; 2) short-term promotors, present in the first successional phases, especially at the stage of transformation of meadow phytocoenoses; 3) stenoecious promotors, confined to various depressions, periodically or permanently overlogged. All succession promotors were characterized by: high fecundity, ability to form polycormones and clones, strong and long-lived underground organs, modification of lifecycles, dual reproductive mode.