Article Fl. Medit. 30: 19-32 https://doi.org/10.7320/FlMedit30.019 Version of Record published online on 7 April 2020 V. Vladimirov, S. Bancheva, M. Delcheva, K. Vassilev & H. Pedashenko Contribution to the knowledge of habitat and vascular plant diversity of Alibotush Reserve, Slavyanka Mountain (Bulgaria) Abstract Vladimirov, V., Bancheva, S., Delcheva, M., Vassilev, K. & Pedashenko, H.: Contribution to the knowledge of habitat and vascular plant diversity of Alibotush Reserve, Slavyanka Mountain (Bulgaria). — Fl. Medit. 30: 19-32. 2020. — ISSN: 1120-4052 printed, 2240-4538 online. Alibotush Reserve is located in Slavyanka Mountain, Southwestern Bulgaria, near the state bor- der with Greece. It was established as protected area in 1951 and currently covers 1638.12 ha, which is about 25% of the Bulgarian territory of the mountain. It has the strictest protection regime according to Bulgaria’s national legislation and corresponds to IUCN category Ia. The article aims to present and analyse the floristic and habitat diversity of the reserve. Altogether 611 species, 287 genera and 72 families of vascular plants are reported for the area. The most species-rich families are Asteraceae, Caryophyllaceae, Poaceae, Fabaceae, Rosaceae. The bio- logical spectrum of the flora, both in respect to biological types and life forms, shows strong prevalence of herbaceous perennials, respectively, hemicryptophytes. The endemism is relative- ly high – ca. 11.5%. The species of conservation concern are 54 (8.8%) and most of them are xerophytes and heliophytes. List of the vascular plant species recorded in the field or from ear- lier literature sources is provided. The habitat diversity is represented by 13 habitat types. Woodland vegetation dominates and covers 1330.5 ha in total, whereas grasslands are repre- sented by 4 habitat types and cover 110.7 ha. A map of the habitats is provided. Key words: Bulgarian flora, floristic diversity, habitats, protected areas, vegetation. Introduction Alibotush Reserve is located in Southwestern Bulgaria, near the state border with Greece, in the Slavyanka Mountain, which until 1955 was called Alibotush as well. The reserve was declared by Decree of the Council of Ministers No. 1171 of 24.09.1951, in order to preserve the unique relict forests of Pinus heldreichii, P. nigra, Abies borisii-regis and the rich flora and fauna. On March 1, 1977 the reserve was included in the World Network of Biosphere Reserves under UNESCO’s Program ‘Man and the Biosphere’. Initially, the area of the reserve was 523.9 ha, but after several extensions the current ter- ritory reaches a total of 1638.12 ha (Order № RD-206 / 04.03.2013 of the Minister of Environment and Water) which is about 25% of the Bulgarian territory of the mountain. During the period 1944–1989, Alibotush Reserve fell into the so-called “border zone” 20 Vladimirov & al.: Contribution to the knowledge of habitat and vascular plant ... which, combined with the difficult accessibility, is the main reason for the preserved nat- ural biodiversity of the mountain. Therefore, the reserve remained poorly studied until nowadays, and there is no published scientific article dealing particularly with the flora and vegetation of the area. The flora of the mountain was most intensively studied in 1920s and 1930s, when sev- eral works were published by N. Stojanov (1921, 1924) and A. Drenovski (1933а, b, 1934а, b, 1936). Later, mainly in connection with the preparation of the multi-volume edi- tion “Flora of Republic of Bulgaria” (since 1963 until now) and of the Red Data Book of the Republic of Bulgaria (Velchev 1984; Peev & al. 2015), a number of botanists visited the mountain and published data on different plant species. Among them, it is worth men- tioning the publications of Kitanov & al. (1983), Pashaliev & Dimitrov (1995), Dimitrov (2010), Aneva & al. (2015). However, a study particularly into the flora of the reserve has not been carried out yet. In most cases, the publications are on the flora of the entire moun- tain or on even the larger Slavyanka floristic region. The territory of the reserve is included in the NATURA 2000 network in Bulgaria, espe- cially in BG0001028 Sreden Pirin – Alibotush site. The article aims to present and analyse the floristic and habitat diversity of Alibotush Reserve with an emphasis on the species of conservation concern. Materials and methods Several field trips were carried out along several transects in the reserve between July 2014 and October 2018. Major habitat types have been studied so as to fully cover the floristic composition. Plant identification and preparation of the species list was done according to Delipavlov & Cheshmedzhiev (2011), Flora of Bulgaria (Jordanov 1963, 1964, 1966, 1970, 1973, 1976, 1979; Velčev 1982, 1989; Kožuharov 1995; Peev 2012). Species of conservation concern and endemic taxa were determined according to Petrova (2006), Petrova & Vladimirov (2009, 2010), Peev & al. (2015), Bulgarian Biological Diversity Act (2002, 2007), Convention on the International Trade in Endangered Species of Wild Fauna and Flora (CITES, https://www.cites.org/eng), Directive 92/43/EEC (1992) and Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention 1979). The chorological elements follow Assyov & Petrova (2012). Life forms follow Raunkiaer (1934) and were determined by the authors and verified with relevant lit- erature sources, e.g. Dimopoulos & al. (2013) and Fischer & al. (2008). The floristic diver- sity of the region is compared to that for the entire country: 4064 species, 921 genera and 159 families (Petrova & Vladimirov 2018). Habitat types were determined according to EUNIS habitat classification (EUNIS 2012) and Directive 92/43/EEC (Interpretation Manual of European Union Habitats 2007, Kavrakova & al. 2009). ‘Habitat directive code’ is abbreviated as ‘HDC’ through- out the text below. Mapping was done using ArcGIS 10.0 software (ESRI 2011). Spatial data was collected in the field using GPS devise Juno BS by Trimble and was later laid over the most recent orthophoto images available. Polygons were outlined manually by using features collected in the field as well as the orthophoto images. Mapping was done in scale 1:5000. Flora Mediterranea 30 — 2020 21 Geographical position of the study area – Alibotush Reserve is situated on the northern slopes of Slavyanka Mt., which is part of the Rila-Pirin Mountain Range and is located to the south of the main ridge of the Pirin Mts (Fig. 1). In morphographic and morphometric traits, Slavyanka Mt. belongs to the high non-glacial mountains. The reserve territory covers the alti- tude range of between 900 and 2200 m a.s.l., which determines the typical mountain climate. The average altitude is about 1500 m. According to the administrative division of the Republic of Bulgaria, the area of Alibotush Reserve falls entirely in the Blagoevgrad district, in the land of Goleshovo (Sandanski mun.), Paril and Nova Lovcha villages (Hadzhidimovo mun.). Climate of the area – According to the climatic zoning of Bulgaria, Slavyanka falls in the Continental-Mediterranean climate, the Pirin region (Velev 2002). The average annual temperature decreases from 9.0°C in the lowest point of the reserve to 2.2°C at an altitude of 2200 m. The warmest months of the year are July and August. Average July tempera- tures are 18.5°C at 1000 m above sea level to 10.5°C at 2200 m (Management plan 2016). The coldest month is January, with temperatures between –1.1°C and –5.7°C. The maxi- mum rainfall is in the winter (November-December) and is in the range of 100–150 mm. The minimum rainfall occurs in August-September and is 30 mm at the mountain’s foot, and up to 50–60 mm in the high mountain parts. Bedrock and soils – The bedrock of almost the entire territory of Alibotush Reserve is formed of marbles of the Dobrostan Marble Branch (Kozhuharov & Marinova 1989). Humus- carbonate soils (randzines) predominate in the reserve, covering 79% of its territory. Brown soils (cambisols) and alluvial-diluvial soils are also spread (WRB, FAO 2015). Results and discussion Floristic diversity – The flora of Alibotush Reserve comprises 72 families, 287 genera and 611 species and subspecies. List of the taxa is provided as Electronic Supplementary File 1 (ESF1). The taxonomic structure of the flora is presented in Table 1. Altogether Lycopodiophyta, Equisetophyta and Polypodiophyta comprise 9.7% of the families, 3.8% of the genera, and 2.5% of the species from the flora, Pinophyta – 4.2% of the fam- ilies, 1.8% of the genera, 1.8% of the species, and Magnoliophyta – 86.1%, 94.4% and 95.7% respectively. Table 1. Taxonomic structure of the flora. 1RRIVSHFLHV 1RRI 1RRI 7D[RQ DQGVXEVSHFLHV JHQHUD IDPLOLHV Lycopodiophyta Equisetophyta Polypodiophyta Pinophyta Magnoliophyta Magnoliopsida 500 227 55 Liliopsida 85 44 7 7RWDO 22 Vladimirov & al.: Contribution to the knowledge of habitat and vascular plant ... Fig. 1. Geographic position of Alibotush reserve. The richest 10 families in specific and subspecific taxa are: Asteraceae (82, 13.4% of the total flora), Caryophyllaceae (44, 7.2%), Poaceae (43, 7.0%), Fabaceae (39, 6.4%), Rosaceae (38, 6.2%), Lamiaceae (31, 5.1%), Scrophulariaceae (25, 4.1%), Brassicaceae (22, 3.6%), Apiaceae (21, 3.4%), Rubiaceae (16, 2.6%). Altogether these families com- prise 59% of the species in the reserve’s flora. These data are somewhat similar to that for the entire Bulgarian flora, in which the richest families are: Asteraceae, Poaceae, Fabaceae, Caryophyllaceae and Brassicaceae (Petrova & al. 2005). The biological spectrum of the flora of Alibotush Reserve is presented in Table 2. The life-form spectrum of the flora of Alibotush Reserve is presented in Table 3. The phytogeographic composition of the flora of Alibotush Reserve is presented in Table 4. The number of species in a reproductive phase of development by months is pre- sented on Fig.