Questions: What is the best grassland management regime for the threatened plant species Gladiolus imbricatus; is the stage structure of local populations a feasible indicator of the effect of changed management.
Location: Coastal meadow system in southwestern Estonia.
Methods: The effect of five management regimes was studied in a long-term (three-year) field experiment: (1) mowing in late July, (2) grazing by cattle, (3) grazing by sheep, (4) sheep grazing during the first year and mowing during subsequent years, (5) no management (control).
Results: The population density increased significantly in response to the mowing treatment and to the mowing after sheep grazing treatment. The proportion of grazed plant individuals was higher in the sheep-grazed than in the cattle-grazed treatment. Generative and vegetative adult individuals of G. imbricatus were significantly more damaged by cattle herbivory than juveniles. All management regimes shifted the population structure towards a dynamic state where juvenile stages dominate, while the not managed control retained a regressive population structure.
Conclusions: Population stage structure was a useful indicator of different management conditions, even in the case where population density did not differ. As indicated by population stage structure, the best management regime for G. imbricatus was either mowing in late July only, or alternation of grazing and mowing in different years.
Nomenclature: Tutin et al. (1972 a.f.).