Novel data on vascular plants of special conservation interest from the Balkans: Mts. Sar Planina

This paper presents georeferenced data, information on habitat preferences, and data on population size estimates for plant species occurring on the ridges of Bistra, Crni Vrh, Kobilica, and Konjuska of the Sar Planina Mts., based on recent field surveys and herbarium specimens deposited in the BEOU and BEO herbaria. The study covers 42 taxa assessed as threatened (i.e. CR, EN or VU) in the flora of Serbia. During this investigation, one species was reported for the first time in Serbia (Aubrieta deltoidea), three species were recorded for the first time in the Kosovo region (Cardamine amara subsp. balcanica, Lycopodium clavatum subsp. clavatum and Scorzonera purpurea), and two taxa were recorded for the first time in the area of the Sar Planina Mts. (Geranium caeruleatum and Satureja subspicata subsp. subspicata). Among the analysed taxa, 13 can be considered very rare, 17 as rare in the Sar Planina area, while 12 are relatively rare. The largest number of taxa (29) have an estimated population size of between 500 and 1,000 reproductive individuals, five taxa have an estimated population size of fewer than 500, while only four taxa have an estimated population size greater than 5,000 reproductive individuals. The results presented significantly fill a knowledge gap and provide the accuracy of data needed for reliable threat assessments and the development of effective conservation action plans for vascular plants in Serbia, while also contributing to a broader understanding of the Balkan flora.