Impact of environmental change on a rare high-mountain tall-herb species: a case study on Achillea lingulata in the Ukrainian Carpathians
Spatio-temporal trends in distribution and population size of Achillea lingulata (Asteraceae), a high-mountain tall-herb species, are analyzed in the Ukrainian Carpathians. These shifts have been revealed due to comparison of the historical literature and herbarium records with the current species distribution, as well as by the long-term monitoring of its populations under different conditions. The species demonstrates opposite dynamic patterns in different types of habitats: negative in abandoned meadows and positive in rock-associated tall-grass communities. That results in the shrinkage of the species distribution at the expense of its secondary grassland habitats, but the increase in size of the saxicolous populations. These trends are associated with the vegetation succession caused by the main drivers of environmental change in the mountains: the abandonment of traditional land use (mainly grazing) and global warming. Biological and habitat characteristics of A. lingulata are described. It has rather narrow habitat requirements and needs gap microsites for the seed recruitment, therefore their availability determines the species distribution and abundance. The post-grazing restoration succession results in denser vegetation cover and replacement of A. lingulata in the meadows. However, vegetation-free microhabitats persist around the rocky outcrops in the high-mountain zone which are most favorable habitats for the species. The evident decline of its lowermost populations implies the effect of climate change which also enhances successional changes. The Ukrainian localities of that rare Carpathian-Balkan species are confined to the northern limit of its geographical range.