Acta Silvae et Ligni 107 (2015), 15-23 Izvirni znanstveni članek / Original scientific paper LOCALITIES AND SITES OF THE SOUTHEASTERN-ALPINE ENDEMIC SPECIES SPIRAEA DECUMBENS KOCH IN BREGINJSKI KOT (NORTHWESTERN SLOVENIA) NAHAJALIŠČA IN RASTIŠČA JUGOVZHODNOALPSKEGA ENDEMITA SPIRAEA DECUMBENS KOCH V BREGINJSKEM KOTU (SEVEROZAHODNA SLOVENIJA) Marko PAVLIN1, Robert BRUS2, Igor DAKSKOBLER23 (1) Borjana, 20, SI-5223 Breginj, markopavlin4@gmail.com (2) University in Ljubljana, Biotechnical Faculty, Department of Forestry and Renewable Forest Resources, Večna pot 83, SI-1000 Ljubljana, robert.brus@bf.uni-lj.si (3) Institute of Biology, Scientific Research Centre of the Slovenian Academy of Sciences and Arts, Regional Unit Tolmin, Brunov drevored 13, SI-5220 Tolmin, igor.dakskobler@zrc-sazu.si ABSTRACT The eastern distribution limit of Spiraea decumbens s. str. is in Breginjski Kot (northwestern Slovenia), where we recorded 49 localities of this eastern-Alpine endemic plant species. We determined two new localities in a new quadrant (9746/4) on riparian rocks of the Nadiža River under Mt. Mija at Kozja Peč, which is currently the southeasternmost point of its entire distribution area. We conducted a phytosociological survey of 26 localities. This endemic occurs in dolomite rock crevices in stands classified within the association Spiraeo-Potentilletum caulescentis. On dolomite screes and torrential fens it is found to dominate on small areas in the succes-sional stages, classified into the provisional association Aquilegio einseleanea-Spiraeetum decumbentis (alliance Petasition paradoxi) and into the new association Spiraeo decumbentis-Seslerietum calcariae (alliance Caricion austroalpinae). These stages are gradually becoming overgrown with thermophilous deciduous trees, and in one of the relevés we found the studied species in an open hop hornbeam stand classified into the association Fraxino orni-Ostryetum. Its populations are vital and unthreatened, except in the two new localities under Mt. Mija, which call for special protection due to their small size and a possibility of being backfilled with gravel. Key words: phytogeography, phytosociology, population ecology, Spiraea decumbens subsp. decumbens, Breginjski Kot, Slovenia IZVLEČEK V Breginjskem kotu (severozahodna Slovenija) smo popisali 49 nahajališč vzhodnoalpskega endemita polegle medvejke (Spiraea decumbens s. str.), ki ima tu vzhodno mejo svojega areala. Ugotovili smo dve novi nahajališči v novem kvadrantu (9746/4), in sicer na obrečnih skalah Nadiže pod goro Mijo pri Kozji peči, kar je za zdaj skrajna jugovzhodna točka celotnega areala. 26 nahajališč smo fitocenološko popisali. Sestoje, kjer ta endemit uspeva v dolomitnih skalnih razpokah, uvrščamo v asociacijo Spiraeo-Potenti-lletum caulescentis. Na dolomitnih meliščih in hudourniških vršajih je na manjših površinah prevladujoč v sukcesijskih stadijih, ki jih uvrščamo v provizorno asociacijo Aquilegio einseleanea-Spiraeetum decumbentis (zveza Petasition paradoxi) in v novo asociacijo Spiraeo decumbentis-Seslerietum calcariae (zveza Caricion austroalpinae). Ti stadiji se postopno zaraščajo s toploljubnimi listavci in na enem popisu smo preučeno vrsto našli v vrzelastem sestoju črnega gabra, ki ga uvrščamo v asociacijo Fraxino orni-Ostryetum. Njene populacije so vitalne in neogrožene, razen na obeh novih nahajališčih pod Mijo, ki bi zaradi majhnosti in mogočega zasutja s prodom morali biti deležni posebne varstvene pozornosti. Ključne besede: fitogeografija, fitocenologija, populacijska ekologija, Spiraea decumbens subsp. decumbens, Breginjski kot, Slovenija GDK= 181.1:176.1Spiraea decumbens s. str.(497.4Breginjski kot)(045)=111 Prispelo / Received: 27. 03. 2015 Sprejeto / Accepted: 28. 10. 2015 1 INTRODUCTION 1 UVOD Spiraea decumbens is a southeastern-Alpine endemic plant species distributed in northeastern Italy and northwestern Slovenia. We distinguish two subspecies, S. decumbens Koch subsp. decumbens, which occurs in northwestern Slovenia and northeastern Italy, and S. decumbens subsp. tomentosa (Poech.) Dostal. = S. decumbens subsp. hacquetii (Fenzl & Koch) Arcang., which occurs in the eastern part of its distribution area, only in northeastern Italy (Aeschimann et al., 2004; Poldini, 2002). The distribution of this endemic plant species in Slovenia was discussed by Wraber (1969), Wraber and Skoberne (1989), Jogan (2000), Dakskobler (2003) and Cusin (2006). They reported the following localities: Tam v Klinu, Tam na Lepem Brdu under Mt. Mali Muzec (Musc), along the Bela above Breginj, at Most na Nadi-zi (Ponte Vittorio) and under Drnohla above the Ucja valley. All its localities known so far in Slovenia have been under the Stol ridge above the Ucja valley and in Breginjski Kot. Spiraea decumbens is listed as rare in the Red List (Anon., 2002). So far, we have conducted 1 Pavlin M., Brus R., Dakskobler I.: Localities and sites of the southeastern-alpine endemic species Spiraea decumbens., phytosociological investigations only of the sites in the rock crevices above the Učja valley, at Plazi and under the mountain pasture Ohoje in Breginjski Kot. These relevés were temporarily assigned to the association Po-tentilletum caulescentis s. lat. (Dakskobler, 2003). The purpose of our study was to record as many localities of this rare endemic species in Breginjski Kot as possible, to study the plant communities on its sites and assess its vitality and potential threat. 1.1 Ecological description of the study area 1.1 Ekološki opis raziskovanega območja Breginjski Kot is situated at the foothills of the Julian Alps and is the westernmost part of Slovenia. It is surrounded by the Stol Mountains in the north, the Na-diža River in the west, by mounts Mija and Ljubija in the south and extends into Staroselsko Podolje lowland in the east. The region has a moist climate with mean annual precipitation exceeding 2500 mm and periodically heavy rain. The bedrock at higher elevations is composed of hard calcareous rocks, dolomite, dolomi-tised limestone and limestone, while the sub-montane belt is dominated by flysch and glacial deposits. The vegetation reflects strong anthropozoogenous influence. Steep and stony areas that were unsuitable for farming are overgrown with forest. Other areas are mainly covered by grasslands that have been subjected to rapid overgrowing in recent decades. The composition of the local flora is dominated by plants of the moderate climatic belt and plants that belong to the boreal geoelement. There are many Mediterranean-montane, Mediterranean and Illyrian species, of which 23 are endemic, mainly southeastern-Alpine (Čušin, 2006). 2 MATERIALS AND METHODS 2 MATERIALI IN METODE In Breginjski Kot, we examined the areas with already known localities and the areas where this species could potentially occur. We used the GPS receiver and a synoptic map where we marked the localities. The coordinates of the localities were entered into the FloVe-gSi database (Seliškar et al., 2003). For a more detailed analysis we selected six areas where we made 26 relevés, applying the standard Central-European method (Braun-Blanquet, 1964). These relevés were entered into the FloVegSi database. Combined cover-abundance values were transformed into ordinal values 1 - 9 (van der Maarel, 1979). Numerical comparisons were made with the software package SYN-TAX 2000 (Podani, 2001). Relevés were arranged into the analytic table (Table 1) based on hierarchical classification and assessment of diagnostic species. We integrated the results of the (unweighted) pair group method with arithmetic mean "(Unweighted) average linkage" - UPGMA, where Wishart's similarity ratio was applied. Phytosociological groups (= groups of diagnostic species) were formed on the basis of our own criteria, but with consideration of numerous authors. The nomenclature source for the names of vascular plants is Martinčič et al. (2007), and Martinčič (2003, 2011) for the names of mosses. The nomenclature source for the names of syntaxa is Šilc and Čarni (2012). On each locality we determined the size of the populations and assessed their vitality and potential threat. Vitality was scored on a scale where 1 = poor, 2 = moderate and 3 = good. 3 RESULTS AND DISCUSSION 3 REZULTATI IN RAZPRAVA 3.1 Phytosociological description of the sites of Spiraea decumbens in Breginjski Kot 3.1 Fitocenološka oznaka rastišč vrste Spiraea decumbens v Breginjskem kotu The 26 relevés in Table 1 were arranged based on hierarchical classification and with consideration of diagnostic species. We found that the relevés in rock crevices and ledges are floristically very similar to those on steep gravel directly under rock faces, as chasmophytic species frequently occur also on screes, and vice versa. Spiraea decumbens usually spreads abundantly on screes and its coverage is considerably higher there than in rock crevices. Relevés 1 and 2 in Table 1 that were made in the area of Kozja Peč are unique and cannot be adequately syntaxonomical-ly classified as yet, but they belong to a chasmophytic community (class Asplenieta trichomanis). Relevés 2 to 10 in Table 1 can be classified into the association Spiraeo decumbentis-Potentilletum caulescentis Poldi-ni 1969. Compared with the stands of this association in the Carnic Alps and in the Italian part of the Julian Alps (Poldini, 1973) they are somewhat floristically impoverished. Some of the species, for example Leontodon tenuiflorus, Athamanta turbith, Primula auricula, which are common or diagnostic in the original table of this association, were therefore not recorded on our plots. Our stands are treated as a special variant with Rhodothamnus chamaecistus, which very rarely occurs in relevés from Italy. The differential species of the variant is also Campanula cespitosa. Relevés 12 to 16 in Table 1 characterise small ledges or steep screes under rock faces, i.e. scree vegetation, which is in fact usually dominated by Spiraea decumbens. For the time being, these stands are named after Spiraea decumbens and Aquilegia einseleana as the provisional associati- 2 Acta Silvae et Ligni 107 (2015), 15-23 on Aquilegio einseleanae-Spiraeetum decumbentis nom. prov. Its diagnostic species are Spiraea decumbens and Aquilegia einseleana, and its differential species are Salix glabra, Campanula cespitosa, Leontodon hispidus subsp. hyoseroides and Rhamnus pumilus. This is a su-ccessional stage that occurs in small areas (from 2 m2 to 10 m2) on initial soil (lithosol) in the overgrowing of dolomite gravel or of rock ledges. It is characterised by coexistence of chasmophytic species, scree species and species of stony subalpine grasslands. This stage, which requires further investigation, is temporarily classified into the alliance Petasition paradoxi, order Arabido alpinae-Petasitetalia paradoxi and class Thla-spietea rotundifolii. Relevés 17 to 25 in Table 1 represent the next stage in succession, extensively overgrown established screes or gravelly grasslands in erosion areas that are very slowly becoming overgrown with shrub and tree species. These stands are classified into the new association Spiraeo decumbentis-Sesleriete-um calcariae ass. nov. Its diagnostic species are Spiraea decumbens, Sesleria caerulea subsp. calcaria, Erica carnea, Polygala chamaebuxus, Molinia caerulea subsp. arundinacea, Allium ericetorum, Polygala nicaeensis subsp. carniolica (= P. nicaeensis subsp. forojulensis) and Chamaecytisus purpureus. The nomenclature type of the new association, holotypus, is relevé 21 in Table 1. The new association is classified into the alliance Ca-ricion austroalpinae, order Seslerietalia coeruleae and class Elyno-Seslerietea. In the next stage of succession, these overgrown screes are sometimes covered with open Ostrya carpinifolia and Fraxinus ornus forest classified into the association Fraxino orni-Ostryetum. An example of such an open forest can be seen in relevé 26 in Table 1. Synsystematic classification of the studied communities into higher units is as follows: Class: Asplenieta trichomanis (Br.-Bl. in Meier & Br. Bl. 1934) Oberd. 1977 Order: Potentilletalia caulescentis Br.-Bl. in Br.-Bl. et Jenny 1926 Alliance: Phyteumato-Saxifragion petraeae Muci-na in Mucina et al. 2011 Association: Spiraeo decumbentis-Potentille-tum caulescentis Poldini 1969 var. Rhodothamnus chamaecistus var. nov. Class: Thlaspietea rotundifolii Br.-Bl. 1948 Order: Arabido alpinae-Petasitetalia paradoxi Mucina et al. 2012 Alliance: Petasition paradoxi Zollitsch ex Lippert 1966 Association: Aquilegio einseleanae-Spiraeetum decumbentis nom. prov. Class: Elyno-Seslerietea Br.-Bl. 1948 Order: Seslerietalia caeruleae Br.-Bl. et Jenny 1926 Alliance: Caricion austroalpinae Sutter 1962 Association: Spiraeo decumbentis-Seslerietum calcariae Dakskobler in Pavlin, Brus et Dakskobler 2015 ass. nov. Class: Querco-Fagetea Br.-Bl. et Vlieger in Vlieger 1937 Order: Quercetalia pubescenti-petraeae Klika 1933 Alliance: Fraxino orni-Ostryion Tomazic 1940 Association: Fraxino orni-Ostryetum Aichinger 1933 corr. Franz 2002 LEGENDA # Breginj-Beia # Breginj-Prekopa # Breginj-Plazi # Breginj-Benetke 0 Breginj-Klin Preostala nahajališča Fig. 1: Localities of Spiraea decumbens under the Stol ridge Slika 1: Nahajališča vrste Spiraea decumbens pod Stolovim grebenom 3 Table 1: Stands with Spiraea decumbens in Breginjski Kot Preglednica 1: Sestoji z vrsto Spiraea decumbens v Breginjskem kotu Number of relevé (Zaporedna številka popisa) 10 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Database number of relevé (Delovna številka popisa) Elevation in m (Nadmorska višina v m) 265 264 900 820 820 850 910 930 910 900 820 850 820 695 700 790 770 790 700 700 790 920 820 Aspect (Lega) NNW NE SE NE SE SE SE SW SE SW Slope in degrees (Nagib v stopinjah) 90 70 100 95 90 90 100 95 70 70 45 40 35 40 40 10 15 40 50 45 25 Parent material (Matična podlaga) Gr Gr Gr Gr Gr Gr Gr Gr Gr Gr Gr Soil (77a) Stoniness in % (Kamnitost v %) 100 100 100 100 100 100 100 100 100 100 100 70 60 30 40 30 20 30 10 100 50 10 Cover in % (Zastiranje v%)\ Tree layer (Drevesna plast) E3 70 Shrub layer (Grmovna plast) E2 20 10 Herb layer (Zeliščna plast) E1 10 40 20 10 30 40 10 25 10 15 30 30 40 50 60 100 95 70 70 90 95 50 Moss layer (Mahovna plast) E0 10 70 10 Number of species (Število vrst) 22 14 16 10 12 14 13 14 13 16 12 30 13 15 27 35 17 33 15 21 30 Relevé area (Velikost popisne ploskve) 1.5 10 12 12 21 3.5 1.5 10 2.5 20 24 20 Date of taking relevé (Datum popisa) Locality (Nahajališče) Quadrant (Kvadrant) Coordinate GK Y (D- Coordinate GKX(D-4 AT Asplenietea trichomanis Pr. Fr. 100 38 31 27 12 Spiraea decumbens E1 26 Potentilla caulescens E1 10 Valeriana saxatllls E1 Rhamnus pumilus E1 Physoplexis comosa E1 Paederota bonarota E1 Asplenium ruta-muraria E1 Asplenium trichomanes E1 Campanula carnica E1 Cystopteris regia E1 Paederota lutea E1 Kernera saxatilis E1 Saxífraga crustata E1 Number of relevé (Zaporedna številka popisa) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Pr. Fr. TR Thlaspietea rotundifolii Aquileqia einseleana E1 + + + 1 1 1 + + + + + 11 42 Hieracium porrifolium E1 1 + + r + + + + + 1 10 38 Petasites paradoxus E1 1 + + 2 + + + + + 9 35 Campanula cespitosa E1 + + + + + + + + 8 31 Biscutella laeviqata E1 + 1 + + + 5 19 Theslum rostratum E1 + 1 + 3 12 Achnatherum calamaqrostis E1 + + 2 8 Leontodon hlspidus subsp. hyoseroldes E1 + + 2 8 Rumex scutatus E1 + + 2 8 Euphrasia cuspidata E1 + + 2 8 Centaurea dichroantha E1 + + 2 8 Hieracium plloselloldes E1 + 1 4 Gypsophlla repens E1 r 1 4 Sllene vulqaris subsp. qlareosa E1 + 1 4 ES Elyno-Seslerietea Sesleria caerulea subsp. calcarla E1 2 + + + + 1 2 1 1 + 4 3 3 3 4 3 4 4 3 4 20 77 Carex mucronata E1 + + 1 + + + + + 1 2 + 1 1 + 1 15 58 Globularia cordlfolla E1 + + + + 2 1 + 1 + 2 3 + 2 13 50 Aster bellidiastrum E1 r + r 3 12 Dryas octopetala E1 + + + 3 12 Betónica alopecuros E1 + + 1 3 12 Laserpitium peucedanoides E1 + + + 3 12 Carex sempervirens E1 + + + 3 12 Thymus praecox subsp. polytrichus E1 + 1 2 8 Gentlana clusli E1 + + 2 8 Carduus crassifolius E1 + 1 4 Helianthemum nummularium subsp. qrandiflorum E1 + 1 4 Leucanthemum maximum s. lat. (L heterophyllum) E1 + 1 4 Phyteuma orblculare E1 + 1 4 Helianthemum alpestre E1 + 1 4 SCf Scheuchzerio-Caricetea fuscae Tofieldia calyculata E1 + + 2 8 Parnassia palustris E1 + 1 4 EP Erico-Pinetea Erica carnea E1 r + + 2 2 4 5 4 4 4 5 4 4 3 1 15 58 Mollnia caerulea subsp. arundinacea E1 + + + 1 + 1 1 1 1 9 35 Polyqala chamaebuxus E1 + + + + + + + 1 1 9 35 Allium erlcetorum E1 + + + + + + + + + 9 35 Polyqala nlcaeensis subsp. carnlollca E1 r + 1 + + + + 1 8 31 Chamaecytlsus purpureus E1 + + + + + + + + 8 31 Rhodothamnus chamaecistus E1 + + + + + + + 7 27 Calamaqrostis varía E1 + + + + 1 1 6 23 Pinus niqra E1 + + + + r 5 19 Buphthalmum salicifolium E1 + + + + 4 15 Aster amellus E1 + + + 3 12 Leontodon incanus E1 + + + 3 12 Gymnadenia odoratisslma E1 + + 2 8 < O) (D O -vi N) O o Number of relevé (Zaporedna številka popisa) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Pr. Fr. Asperula aristata E1 + + 2 8 Carex ornithopoda E1 + + 2 8 Epipactis atrorubens E1 + + 2 8 Genista radiate E1 + 1 4 Rhododendron hirsutum E1 1 1 4 Ameianchier ovaiis E1 + 1 4 Rubus saxatiiis E1 + 1 4 FB Festuco-Brometea Galium verum E1 + + + + + 5 19 Peucedanum oreoselinum E1 1 + + 1 4 15 Euphorbia cvparlssias E1 + + 2 8 Carex humllls E1 + + 2 8 Gymnadenia conopsea E1 + + 2 8 Carlina acaulis E1 + + 2 8 Teucrlum montanum E1 + 1 4 Hlppocrepis comosa E1 + 1 4 Brachypodlum rupestre E1 r 1 4 Stachys recta E1 + 1 4 Galium lucidum E1 + 1 4 TG Trifolio-Geranietea Polyqonatum odoratum E1 + + + 3 12 Laserpltium siler E1 r + 2 8 Thesium bavarum E1 + + 2 8 Viola hirta E1 + + 2 8 Trise turn arqenteum E1 + 1 4 Anthericum ramosum E1 + 1 4 Laserpitium latifolium E1 + 1 4 MA Molinio-Arrhenatheretea Lotus cornlculatus E1 + + 2 8 Deschampsla cespitosa E1 r 1 4 Taraxacum officinale E1 + 1 4 Mo Laserpltium prutenicum E1 + 1 4 BA Betulo-Alnetea Sallx qlabra E2a 1 + 2 1 + 5 19 Sallx qlabra E1 + + + + + 1 3 7 27 Salix appendlculata E1 + + 2 8 FS Fagetalia sylvaticae Cyclamen purpurascens E1 r + + + + 5 19 Faqus sylvatlca E1 r + 2 8 Phyllitls scolopendrlum E1 + 1 4 Aruncus diolcus E1 + 1 4 Campanula trachelium E1 r 1 4 Euphorbia dulcís E1 r 1 4 Neottla nidus-avis E1 + 1 4 Acer pseudoplatanus E1 + 1 4 QP Quercetalia pubescenti-petraeae Fraxinus ornus E3b + 1 4 Fraxinus ornus E3a 1 1 4 Fraxinus ornus E2a + 1 1 3 12 Fraxinus ornus E1 + + + + + + + + + 1 10 38 CO C o O" 0) Q. o C Q. (D 3 tb ai & o e 3 torb S Oí Number of relevé (Zaporedna številka popisa) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Pr. Fr. Carex flacca E1 1 1 3 3 + 5 19 Ostrya carpiniíolia E3b + 1 4 Ostrya carpiniíolia E3a 3 1 4 Ostrya carpiniíolia E2b + 1 4 Ostrya carpiniíolia E2a + + + 3 12 Ostrya carpiniíolia E1 + + + + + + 6 23 Sorbus arla E2b + 1 4 Sorbus aria E2a + + 2 8 Sorbus arla E1 + + + 3 12 Hierochloé australls E1 + 1 4 QF Querco-Fagetea Cephalanthera lonqllolla E1 + 1 2 8 Hederá helix E1 + 1 4 Hepatlca nobilis E1 + 1 4 Clematis vitalba E1 + 1 4 Potentllla erecta E1 + 1 4 Viola rlvinlana E1 + 1 4 SP Salicetea purpureae Salix eleaqnos E2a + + + 3 12 Salix eleaqnos E1 + 1 4 Sallx purpurea E1 + 1 4 VP Vaccinio-Piceetea Veronica urtlcifolia E1 2 r 2 8 Picea abies E1 + + 2 8 Solidaqo vlrqaurea E1 + 1 4 0 Other species (Druqe vrste) Junlperus communis E1 + + 2 8 Selaqinella helvetica E1 1 1 4 Rubus caeslus E1 + 1 4 ML Mosses and lichens (Mahovi in lišaji) Tortella tortuosa EO + + + + 4 15 Conocephalum conlcum EO + 1 4 Marchantía polymorpha EO 1 + 2 8 Brachytheclum rutabulum EO 1 1 4 Tortella sp. EO 2 1 4 Muscl sp. EO 4 1 4 Orthotheclum rufescens EO 1 1 4 Scleropodium purum EO + 1 4 Neckera crispa EO 1 1 4 Homalotheclum lutescens EO + 1 4 Legend - Legenda A Limestone - apnenec D Dolomite - dolomit Gr Gravel - gnišč R Rendzina - rendzina Li Lithosols - kamnišče Mo Molinietalia caeruleae Relevés (popisi] 1-2: Spiraea decumbens community (Asplenietea trichomanis) Relevés (popisi] 3-11: Spiraeo-Potentilletum caulescentis Relevés (popisi] 12-16: Aquilegio-Spiraeetum decumbentis nom. prov. Relevés (popisi] 17-25: Spiraeo-Seslerietum calcaiiae Relevé [popis) 26: Fraxino orni-Ostiyetum Pavlin M., Brus R., Dakskobler I.: Localities and sites of the southeastern-alpine endemic species Spiraea decumbens., Table 2: List of areas with localities of Spiraea decumbens in Preglednica 2: Seznam območij z nahajališči vrste Spiraea Breginjski Kot decumbens v Breginjskem kotu Area / Območje Number of relevés / Število popisov Date of relevé /Datum popisa Quadrant / Kvadrant Breginj-Bela 9 21.5.2014 9746/2 Breginj-Prekopa 6 21.5.2014 9746/2 Breginj-Plazi 5 21.5.2014 9746/1 Breginj-Benetke 3 21.5.2014 9746/1 Breginj-Klin 1 21.5.2014 9746/1 Nadiža-Kozja peč 2 11.7.2014, 20.6.2014 9746/4 3.2 Overview of areas with localities of Spiraea decumbens 3.2 Pregled območij z nahajališči vrste Spiraea decumbens All determined localities of Spiraea decumbens were divided into six areas. Localities in the areas of Bela, Prekopa, Plazi, Benetke and Klin are shown in Figure 1, localities in the area of Kozja Peč in Figure 2. 3.3 Description of Spireae decumbens populations in Breginjski Kot 3.3 Opis populacij vrste Spiraea decumbens v Breginjskem kotu 3.3.1 Area Breginj-Bela 3.3.1 Območje Breginj-Bela This area comprises the river bed of a torrential tributary of the Bela, which is in the process of becoming overgrown. Its catchment area is under Mt. Musc. The overgrowing of screes began after 1933 when concrete torrential barriers were built there. This reduced flow velocity and prevented transportation of gravel. During the construction of barriers on the Bela, a large area was reforested, mainly with the conifers Picea abies, Pinus nigra, Pinus sylvestris, Larix decidua (Kočar, 1999). In this area, Spiraea decumbens grows between the last and its preceding barrier at the elevation between 695 m and 820 m. Nine relevés were made there. The geological bedrock is talus or dolomite rock. Spiraea decumbens grows in two basic vegetation types, in stony grassland on overgrown scree (Spiraeo decumbentis-Seslerietum calcariae) and in a chasmophytic community (Spiraeo decumbentis-Potentilletum caulescentis). Especially interesting is the secondary locality in the crevices on the uppermost concrete torrential barrier. Researchers have not reported such secondary localities for Slovenia until now, or they have not been known. Wraber (1969) saw them in Pušja Vas (Venzone) in Italy, where Spiraea decumbens grows on Fig. 2: Localities of Spiraea decumbens under Mt. Mija (Kozja Slika 2: Nahajališča vrste Spiraea decumbens pod Mijo (Kozja Peč) peč) 8 Acta Silvae et Ligni 107 (2015), 15-23 old walls. Most localities are on gentle slopes facing south and southeast; the slope ranges between 5° and 35°, except on two localities where it reaches 80° and 90°, respectively. The area occupied by Spiraea decumbens varies, ranging from 2.5 m2 to 12 m2 in size. On most of the plots it covers between 25 % and 50 % of the surface area (value 3), but it is very scarce on two plots where it covers only a small part of the surface area (value +). The shrubs on stony grasslands grow to be the tallest, reaching up to 40 cm in height. Shrubs growing on the scree and in rock crevices are slightly shorter, up to 20 cm. The population is vital and not potentially threatened. 3.3.2 Area Breginj-Prekopa 3.3.2 Območje Breginj-Prekopa Prekopa is a botanically fascinating area with several habitats listed in Annex I to the Habitats Directive (Čušin, 2006). The slope gradient contributes to the erodibility of the dolomite slopes and the overgrowing of screes is very slow. Screes face towards the (south) east and (south)west and there is a mountain trail leading across the ridge towards Mt. Musc. All localities (six relevés) are on the top of the eastwards facing scree, but we did not find any localities on the western side. The elevation ranges between 900 m and 920 m, the geological bedrock is talus or dolomite. Two vegetation types prevail: scree community (Aquilegio ein-seleanae-Spiraeetum decumbentis) and chasmophytic community (Spiraeo-Potentilletum caulescentis). Spiraea decumbens localities face north, northeast, east and southeast, on slopes of 40° to 95°. The smallest sample plot measures 2 m2 and the largest 21 m2. Spiraea decumbens coverage varies among plots; it was assessed as + on three plots and as 1, 2 and 3 on the remaining three (according to the Braun-Blanquet scale, 1964). Shrub height does not exceed 20 cm. The population is vital and not potentially threatened. 3.3.3 Area Breginj-Plazi 3.3.3 Območje Breginj-Plazi Plazi is situated to the west of Prekopa. This area comprises known localities of several eastern-Alpine taxa that are rare in Slovenia: Thesium rostratum, Physoplexis comosa and Paederota bonarota. The first locality of Spiraea decumbens is only about a metre away from the road, on an already heavily overgrown slope planted with black pine. Other localities are situated at the bottom of two narrow gorges of the Plazi stream and on precipitous rock faces. It is in these two gorges that Spiraea decumbens population is the most abundant. The localities were recorded at 790 m to 820 m a.s.l., but Spiraea decumbens can grow even higher here, up to 1000 m a.s.l. The bedrock on four plots is dolomite and talus on one plot. Localities face different directions: west, northeast, south and east. Three plots, where we recorded a chasmophytic community, have a slope of 90° to 100° and two plots have a slope of 40° or 50°. The smallest plot measures 2 m2 and the largest 12 m2. On most plots, Spiraea decumbens covers less than 10 % of the surface area (value 1), whereas on one plot of 7 m2 it covers more than 50 % of the surface area. Shrub height ranges from 20 cm in rock crevices to 35 cm on scree. The Spiraea decum-bens population on this locality is the largest, vital and not threatened. 3.3.4 Area Breginj-Benetke 3.3.4 Območje Breginj-Benetke This is a steep dolomite erodible area of about 0.05 km2 to the west of Plazi. We made three relevés on spots that are not subject to erosion and allow for the growth of Spiraea decumbens. These localities are situated at an altitude between 820 m and 850 m. Above the mountain pastures Ohoje and Javornik, localities can be found as high as 1200 m. One plot is on slightly overgrown scree and two are in rock crevices. The localities face south, north and northwest. The slope on two plots is 40° and 100° on the third. The population of Spiraea decumbens is small here, with the largest plot measuring 4 m2 and the smallest only 1.5 m2. Spiraea decumbens covers more than 50 % of the surface area on two plots and less than 10 % on the third. Shrub height does not exceed 25 cm. The population is vital and not threatened. 3.3.5 Area Breginj-Klin 3.3.5 Območje Breginj-Klin The locality is situated on heavily overgrown scree, in an open forest stand on rendzina at about 100 m above the mountain trail leading to Brezje (Montema-ggiore) village in Italy. The tree layer covers 70 %, the shrub layer 10 % and the herb layer 80 % of the plot. Only one locality nearby has a higher coverage, but could not be recorded because of the damages caused by sleet. The trees here are up to 6 m high and not thicker than 20 cm. Thermophilous deciduous trees form the tree and the shrub layer: Fraxinus ornus, Ostrya carpi-nifolia and Sorbus aria. Fagus sylvatica and Acer pseu-doplatanus occur in the herb layer along with manna ash and whitebeam. The geological bedrock consists of talus. The plot is situated 820 m a.s.l. and faces west. The slope gradient is 25°. Spiraea decumbens grows in an area of 20 m2 and covers less than 50 % of the surface area. The tallest specimen of Spiraea decumbens 9 Pavlin M., Brus R., Dakskobler I.: Localities and sites of the southeastern-alpine endemic species Spiraea decumbens., was measured here at 50 cm, whereas most shrubs on the plot reach the average height of 30 cm. While vital, the population may become near threatened if the overgrowing of the scree continues. 3.3.6 Area Nadiža-Kozja Peč 3.3.6 Območje Nadiža-Kozja Peč At the foothills of Mija, under Kozja Peč on the right bank of the Nadiža, Marko Pavlin, the youngest of three authors, discovered on 20 June 2014 two new localities of Spiraea decumbens in the new quadrant 9746/4, about 400 m air distance apart. Igor Dakskobler picked a specimen for the Herbarium of the Institute of Biology SRC SASA (LJS) on 11 July 2014. These are for now the southeasternmost localities in the entire distribution area of this species and the first in the Mija Mountains. All other localities in the territory of Slovenia are in the Stol Mountains. There is only one shrub on each, which leads to the conclusion that the seeds were deposited by the Nadiža from its headwaters (hydro-chory). The elevation of the plots was around 265 m, the slope 70° towards northwest (the first plot) and 90° towards north (the second plot). In contrast to other 24 plots, the geological bedrock under Mija consists of limestone. The plot with easier access measures 1.5 m2 with Spiraea decumbens covering less than 10 %. The tallest specimens are below 30 cm and are vital. The river flow in this part is periodically regulated through 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 Fig. 3: Distribution of Spiraea decumbens s. str. in Slovenia gravel excavation and could become backfilled, so we alerted the Institute for Nature Conservation about this locality. The second locality under Kozja Peč is in much less accessible rocks above the Nadiža pool and could be threatened by visitors who come here for a summer swim. The distribution map of Spiraea decumbens in Slovenia with marked new locality is shown in Figure 3. 4 CONCLUSIONS 4 ZAKLJUČKI We recorded 47 localities of the southeastern-Alpine endemic species Spiraea decumbens in five areas (the Bela headwaters, Prekopa, Plazi, Benetke and Klin) under the Stol ridge in Breginjski Kot (northwestern Slovenia) in the elevation belt of 700 m to 1200 m. All of them are situated in the existing quadrants of the Central-European flora mapping grid, 9746/1 and 9746/2. Based on the relevés made on 21 localities, we classified the recorded stands into the following associations: Spiraeo decumbentis-Potentilletum caulescentis Poldini 1969, Aquilegio einseleanae-Spiraeetum decumbentis nom. prov., Spiraeo decumbentis-Seslerietum calcariae Dakskobler in Pavlin, Brus et Dakskobler 2015 ass. nov. and Fraxino orni-Ostryetum Aichinger 1933 corr. Franz 2002. Both, the provisionally and newly described association are successional stages in the overgrowing of dolomite screes and torrential fans with thermophilous deciduous trees, in particular Ostrya carpinifolia, Fraxi- Slika 3: Razširjenost vrste Spiraea decumbens s. str. v Sloveniji 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 10 Acta Silvae et Ligni 107 (2015), 15-23 nus ornus and Sorbus aria, sporadically also with individual Pinus nigra trees. Despite several attempts, we did not manage to confirm the Spiraea decumbens locality at the gravel bar on the Nadiža that had been reported by Wraber (1969) and which Čušin (2006) had failed to find as well. However, we found two new localities in the new quadrant (9746/4) at the northern foot of Mt. Mija, at Kozja Peč on the right bank of the Nadiža River. These two localities differ from all other localities investigated in our study, both in terms of ecology (the geological bedrock is limestone) and floristics. Only two clusters of Spiraea decumbens overgrow steep riverine rocks and overhangs. We assume that its seeds had been deposited here by water. Spiraea decumbens is potentially threatened by swimmers in the new localities under Mija and even more by gravel extraction that takes place with the regulation of the river bed. This small population should therefore be carefully monitored and protected, especially because it is the southeasternmost locality in its entire distribution area. On other localities, Spiraea decumbens thrives either in small patches or tufts, or in large clusters in areas ranging from 1.5 m2 to 24 m2 in size. The largest population of Spiraea decumbens was found in the area Plazi, where favourable site conditions facilitate its growth in a larger area (screes, rock barriers and solitary rocks). The vitality of individuals on most localities is good, even on slightly shaded sites. Dry individuals that have probably died off because of their physiological age are only rarely observed. The species also regenerates well, although only in limited areas. All this points to predominantly vegetative propagation, which is most distinct in rock crevices. 5 POVZETEK 5 SUMMARY Na petih območjih (povirje Bele, Prekopa, Plazi, Benetke in Klin) pod Stolovim grebenom v Breginjskem kotu (severozahodni Slovenija) smo popisali 47 nahajališč jugovzhodnoalpskega endemita polegle med-vejke (Spiraea decumbens) v višinskem pasu od okoli 700 m do 1200 m. Vsa so v že znanih kvadrantih srednjeevropskega kartiranja flore, 9746/1 in 9746/2. Na 21 nahajališčih smo naredili tudi fitocenološki popis in popisane sestoje uvrščamo v naslednje asociacije: Spiraeo decumbentis-PotentiUetum caulescentis Poldini 1969, Aquilegio einseleanae-Spiraeetum decumbentis nom. prov., Spiraeo decumbentis-Seslerietum calcariae Dakskobler in Pavlin, Brus et Dakskobler 2015 ass. nov. in Fraxino orni-Ostryetum Aichinger 1933 corr. Franz 2002. Obe, provizorna in novo opisana asociacija, sta sukcesijska stadija v zaraščanju dolomitnih melišč in hudourniških vršajev s tolploljubnimi listavci, pred- vsem črnim gabrom, malim jesenom in mokovcem, posamično tudi s črnim borom. Kljub večkratnemu iskanju nam ni uspelo potrditi nahajališča polegle med-vejke na prodišču pri Mostu na Nadiži, ki ga navaja Wraber (1969) in ga je zaman iskal tudi Čušin (2006). Našli pa smo dve novi nahajališči v novem kvadrantu (9746/4) na severnem vznožju Mije, pri Kozji peči na desnem bregu Nadiže. Ti dve nahajališči se tako ekološko (geološka podlaga je apnenec) kot floristič-no precej razlikujeta od vseh drugih pregledanih nahajališč. Vrsta Spiraea decumbens v dveh šopih pora-šča strme do previsne obrečne skale in je njeno seme najbrž prinesla voda. Na obeh novih nahajališčih pod Mijo poleglo medvejko potencialno ogrožajo kopalci in predvsem izkopavanje proda med regulacijami rečne struge, zato mora biti ta mala populacija deležna skrbnega spremljanja in varstva, tudi zato, ker je najbolj jugovzhodna v celotnem arealu. Na drugih nahajališčih polegla medvejka raste v majhnih krpah oziroma blazinicah ali večjih šopih na površini od 1,5 m2 do 24 m2. Njeno največjo populacijo smo ugotovili v območju Plazi. Tam so zanjo na večji površini ugodne rastiščne razmere (melišča, skalni pragovi in osamelci). Vitalnost osebkov je na večini nahajališč dobra, tudi na že nekoliko zasenčenih rastiščih. Le redko lahko ponekod opazimo suhe osebke, ki so najverjetneje odmrli zaradi fiziološke starosti. Vrsta se tudi dobro pomlajuje, vendar le na omejenih površinah. Iz tega sklepamo na prevladujoče vegetativno razmnoževanje. Najbolj je to opazno v skalnih razpokah. 6 ACKNOWLEDGEMENTS 6 ZAHVALA The study is the result of the graduation thesis (Pavlin, 2015) written by the younger author under the mentorship of the senior authors. Sincere thanks to Prof. Dr. Franc Batič for his insights and comments. Dr. Lado Kutnar and Dr. Aleksander Marinšek helped us with valuable improvements and corrections. English translation by Andreja Šalamon Verbič. 7 REFERENCES 7 LITERATURA Aeschimann D., Lauber K., Moser D. M., Theurillat J.-P. 2004. Flora alpina. Bd. 1: Lycopodiaceae-Apiaceae. Bern, Stuttgart, Wien,Haupt Verlag: 1159 p. Anonymus 2002. Pravilnik o uvrstitvi ogroženih rastlinskih in živalskih vrst v rdeči seznam. Priloga 1: Rdeči seznam praprotnic in semenk (Pteridophyta & Spermatophyta). Ljubljana, Uradni list RS 82/2002. Braun-Blanquet J. 1964. Pflanzensoziologie. Grundzüge der Vegetationskunde. 3.izd. Wien; New York, Springer: 865 p. Čušin B. 2006. Rastlinstvo Breginjskega kota. 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Rdeči seznam ogroženih praprotnic in semenk SR Slovenije. Varstvo narave (Ljubljana), 14-15: 1-429. Fig. 6: Stand of the provisional association Aquilegio einse- Slika 6: Sestoj provizorne asociacije Aquilegio einseleanae-leanae-Spiraeetum decumbentis. Photo: M. Pavlin Spiraeetum decumbentis. Foto: M. Pavlin Fig. 7: Spiraea decumbens and Rhododendron hirsutum flourishing on overgrown scree in the stand of the association Spiraeo decumbentis-Seslerietum calcariae. Photo: M. Pavlin Slika 7: Polegla medvejka in dlakavi sleč cvetita v sestoju asociacije Spiraeo decumbentis-Seslerietum calcariae. Foto: M. Pavlin 13 Pavlin M., Brus R., Dakskobler I.: Localities and sites of the southeastern-alpine endemic species Spiraea decumbens., Fig. 8: Secondary locality of Spiraea decumbens in the crevic- Slika 8: Subspontano pojavljanje polegle medvejke na betones on the uppermost concrete torrential barrier in the chan- ski pregradi v hudourniški strugi Bele. Foto. M. Pavlin nel of a torrential tributary of the Bela. Photo: M. Pavlin Fig. 9: New locality of Spiraea decumbens near Kozja Peč on the right bank of the Nadiža River. Photo: M. Pavlin Slika 9: Novo nahajališče polegle medvejke pri Kozji peči na desnem bregu Nadiže. Foto: M. Pavlin Fig. 10: The second new locality of Spiraea decumbens near Kozja Peč on the right bank of the Nadiža. Photo: M. Pavlin Slika 10: Drugo novo nahajališče polegle medvejke pri Kozji peči na desnem bregu Nadiže. Foto: M. Pavlin 14