Unitary and iterative growth of clonal species individuals: significance for the spatial structure and the dynamics of population abundance
The aim of the study was to determine the dynamics of unitary and iterative genets and the ramets which they produce in the populations of two species represent diverse types of clonal growth: Filipendula ulmaria (L.) Maxim. and Lythrum salicaria L. An attempt was made to answer the following questions: Is there a demographic balance between the number of ramets produced by genets, i.e. vegetative reproduction, and recruitment of new genets? How significant may quantitative relations between unitary and iterative individuals be for the spatial structure and population abundance dynamics?
There was similarity in the dynamics of the abundance of genets and ramets in the Filipendula ulmaria and Lythrum salicaria populations. A slight increase in the number of genets and ramets was noted in the second study season. In the subsequent vegetation seasons, a decline in their number was observed. There was no statistically significant differences in the share of unitary and iterative individuals and ramets that they produced. The populations are characterized by a spatial clumped structure. During the observation, an increase in the mean number of ramets per one individual and the aggregation coefficient (Leksis' index) were noted.
Population of the species of hydrogenic habitats situated in river valleys are particularly exposed to groundwater fluctuations. In the study area, a rapid rise of the groundwater level related to beaver activity was observed. Water stress resulted in weaker growth of the existing genets and, first of all, in lower recruitment of new ones. Intensive vegetative growth of Carex acutiformis individuals and increase in the necromass layer thickness have a big significance for the population dynamics of the study species.