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Growth, survival and generative reproduction in a population of a widespread annual hemiparasite Melampyrum pratense

Průšová, Monika, Lepš, Jan, Štech, Milan, Těšitel, Jakub
Biologia 2012 v.68 no.1 pp. 65-73
Melampyrum, biomass, branches, fecundity, forest communities, forests, growing season, habitats, herbivores, intraspecific competition, life history, mortality, population dynamics, seedlings, seeds, vegetative growth, vegetative propagation, Europe
Melampyrum pratense is one of the most successful root-hemiparasitic species of temperate Europe occurring in various habitats including both forest and open communities. The species shares its life history traits (large seeds, annuality, lack of clonality) with most of other hemiparasitic Orobanchaceae. Due to lack of vegetative propagation, the reproductive success of a M. pratense individual largely depends on the seed production. We used an individual-based observation of ontogenetic development of plants and analysed the development of spatial distribution of individuals to reveal links between fecundity of individuals and their vegetative growth in the context of population dynamics within one growing season. We demonstrated a tight dependency of seed production on vegetative growth and survival till the end of the growing season. Plants that were still alive and big (due to a high number of lateral branches) in the end of August produced the highest numbers of seeds. These were several times higher than the population average due to positively skewed distribution of seed production across individuals. The rate of premature mortality was rather low (below 50%) once seedlings successfully emerged and was most likely caused by intraspecific competition. By contrast, moderate level of herbivory (stem clipping by grazers) had a limited effect on the survival and the inflicted biomass losses seemed compensated. Therefore, despite being an annual, M. pratense appears well-adapted to its life in perennial-dominated forest communities, which is also underpinned by its hemiparasitic strategy providing essential resources and allowing to avoid below-ground competition.