Population of Gladioulus imbricatus under diverse management regimes in SW Estonia

Abstract

The sword lily Gladiolus imbricatus is an endangered species within plant communities of semi-natural grasslands. Coastal meadows, extensively managed as pastures or meadows, are amongst its favored habitats and thrive with biodiversity in fauna and flora. However, following major land-use changes during the last century, proactive endeavors are necessary to prevent a loss of rare fauna and flora under overgrowing conditions. Long-term experiments and monitoring serve as strong references for observing developments in changing environments. The three-year permanent plot experiment in this study evaluates the performance of a large population of G. imbricatus, subjected to different types of management practices including mowing at different dates and grazing at different intensities. The experimental setup was established in 2021 and comprises 36 plots in four different sites, characterized by different combinations of management types. The aim was to identify preliminary trends of G. imbricatus distribution with respect to the management types, and to identify ecological preferences of G. imbricatus with regards to the surrounding vegetation.The findings from this study confirmed a higher total count of G. imbricatus in the meadows compared to the pastures. Mowing in the first half of July was preferred to late mowing, and grazing at high intensity was worse. In addition, crushing was found to be less favorable for the abundance of G. imbricatus compared to other management practices, and reedbeds had the lowest counts across all sites. With regards to its ecological preferences, a positive correlation between the count of G. imbricatus and the number of species in all sites was found. Positive trends in the vegetative height of surrounding vegetation were observed in the pastures, while negative trends were observed in the meadows. An important result is also the great difference not only between managements but also between sites in their response to the year.The results from this study highlight the importance of long-term assessment of restoration and recovery and provide preliminary insights about preferred management strategies in the long term, offering a broad view of the ecological preferences of G. imbricatus in an extensively managed coastal meadow.