Does the accidental burning in Molinion caeruleae meadow influence regeneration of Inula salicina L. population?

Inula salicina L. belongs to species prone to progressive diminishing of population numbers in Europe, particularly threatened by the abandonment of traditional use in semi-natural habitats leading to secondary succession. The presented investigations were addressed to assess the impact of accidental burning of plant cover in a Molinion caeruleae meadow on regeneration of its population of Inula salicina. The observations were conducted in Kraków (Southern Poland) in the years 2017–2019 in two line transects, each with 10 permanent plots established in permanent study plots placed in a patch accidentally burned in the year 2015 and in an unburned one. The significantly greater number of vegetative and generative stems in the burned patch during the whole study period might be a consequence of vegetative spread or/and successful seedling recruitment and site colonization directly after disturbance. The absence of seedlings of Inula salicina at both study sites in the years 2017–2019 might be the result of unfavorable environmental conditions, while the lack of temporal variability in the number of vegetative and generative stems might be caused by the moderate rate of clonal multiplication. The increase in height of generative stems, number and dimensions of leaves, number of inflorescences and diameter of receptacle with disc flowers of the largest inflorescence in subsequent study seasons might be a response to progressive secondary succession and the overgrowing of both study sites. In turn, the lack of uniform spatial variability of the aforementioned traits might suggest that observations of effects of burning should be conducted over a longer time period. Concluding, controlled burning might contribute to regeneration of populations of Inula salicina in abandoned meadows. Moreover, considering the promising results of the performed investigations, it might be stated that further studies on the post-fire regeneration of other meadow species are still required.