The influence of vegetation structure on the composition of the seed rain and seedling pool in abandoned Molinion caeruleae meadows

The investigations of the effect of different habitat conditions on the composition of the seed rain and seedling pool were conducted in the years 2014 and 2015 in abandoned patches of Molinion caeruleae dominated by small-stature meadow taxa (patch I), tall growing grasses (patch II), as well as shrubs and trees (patch III). Observations showed that along the successional gradient the seed rain and seedling pool diminishes. The prevalence of perennials and native taxa in the seed rain and seedling pool occurred in all the study sites. Moreover, in the propagule and seedling pools of all the patches hemicryptophytes and meadow taxa prevailed but their number decreased in successional sites. Also, the abundance of ruderal and grassland taxa decreased gradually, at expense of number of forest species. Zoochorous species prevailed in the seed rain and seedling pool of all patches. Number of hydrohorous species decreased in successional patches, while the abundance of species with other dispersal modes were similar. Irrespective of patch character, the species producing propagules with medium size dominated in the seed rain and seedling pools, whereas a significant decrease of number of small-seeded species was noticed only in the seedling pool. Despite the diminishing of the seed rain and seedling pool along the successional gradient, the gap creation might be a very effective way of active protection of Molinion caeruleae meadows. However, the gap colonisation requires permanent monitoring to avoid further spreading of undesired taxa.