O Hacquetia 15/1 • 2016, 67-91 DOI: 10.1515/hacq-2016-0009 DE GRUYTER OPEN Two new pioneer communities of Sorbus aucuparia and Sorbus aria in the southern Julian Alps Igor Dakskobler1 Key words: phytosociology, syndynamics, successional stage, Sorbus aucuparia, Sorbus aria, Natura 2000, Julian Alps, western Slovenia. Ključne besede: fitocenologija, sindinamika, sukcesijski stadij, Sorbus aucuparia, Sorbus aria, Natura 2000, Julijske Alpe, zahodna Slovenija. Abstract In the southern Julian Alps we described two communities whose tree layer is dominated by species from the genus Sorbus and noted two successional stages in the overgrowing of abandoned agricultural land (pastures, hay meadows). In the secondary succession on former subalpine pastures above the alp Planina Razor und under the Breginjski Stol ridge, where potential natural vegetation consists of subalpine beech forest, dwarf pine has been overgrown with mountain ash (Sorbus aucuparia) whose stands are classified into the new association Rhododendro hirsuti-Sorbetum aucupariae. Whitebeam (Sorbus aria) has established itself on steep former hay meadows in the belt of altimontane beech forests under Mts. Jalovnik and Krikov Vrh, on gullied slopes on mixed geological bedrock dominated by chert, and these stands are classified into the association Calamagrostio arundinaceae-Sorbetum ariae. While occupying only small areas these two pioneer stages, as the sites of some rare or protected species, are nevertheless important biotopes and play a vital role in protection against avalanches. Izvleček V južnih Julijskih Alpah smo opisali dve združbi, v katerih sta v drevesni plasti dominantni vrsti iz rodu Sorbus in opozorili na dva sukcesijska niza v zaraščanju opuščenih kmetijskih površin (pašnikov, senožeti). V drugotni sukcesiji na nekdanjih subalpinskih pašnikih nad planino Razor in pod grebenom Breginjskega Stola, kjer je potencialno naravna vegetacija subalpinski bukov gozd, je rušje prerasla jerebika (Sorbus aucuparia) in njene sestoje uvrščamo v novo asociacijo Rhododendro hirsuti-Sorbetum aucupariae. Na strmih nekdanjih senožetih v pasu altimontanskih bukovih gozdov pod Jalovnikom in Krikovim vrhom pa se na mešani geološki podlagi, kjer prevladuje roženec, v užlebljenih pobočjih uveljavi mokovec (Sorbus aria) in njegove sestoje uvrščamo v asociacijo Calamagrostio arundinaceae-Sorbetum ariae. Opisana pionirska stadija imata kljub majhnim površinam pomembno varovalno vlogo pred snežnimi plazovi in Received: 28. 4. 2015 biotopski pomen, kot rastišča nekaterih redkih ali zavarovanih vrst. Revision received: 15. 10. 2015 Accepted: 18. 10. 2015 1 Institute of Biology, Scientific Research Centre of the Slovenian Academy of Sciences and Arts, Regional unit Tolmin, Brunov drevored 13, SI-5220 Tolmin, and Biotechnical Faculty of the University in Ljubljana, Department of Forestry and Renewable Forest Resources, Večna pot 83, SI-1000 Ljubljana. E-mail: Igor.Dakskobler@zrc-sazu.si 30 O Hacquetia 15/1 • 2016, 67-91 I. Dakskobler Two new pioneer communities of Sorbus aucuparia and Sorbus aria in the southern Julian Alps Introduction Several years ago we described a pioneer community of mountain ash (Sorbus aucuparia) and green alder (Alnus viridis) — Alno viridis-Sorbetum aucupariae on former grazing areas and abandoned mountain pastures in the belt of altimontane and subalpine beech forests in the southern Julian Alps and their foothills (Dakskobler et al. 2013). In 2014 and 2015 we observed a similar forest type in these mountains, with dominating mountain ash in the tree layer and dominating dwarf pine (Pinus mugo) in the shrub layer. Such stands, also of pioneer origin, were found in the level ground Na Polju above the alp Planina Razor and under the ridge of Breginjs-ki Stol. Presumably, there used to be beech forest that was later burned and turned into pastures. These were abandoned decades ago and subsequently dwarf pine was the first to establish itself in the succession, followed by mountain ash. Another form of pioneer forest on former agricultural areas was observed on sunny slopes of Mt. Jalovnik above the village Sela nad Podmelcem and un- der Mt. Krikov Vrh above the alp Kuk (Podkuk). Steep hay meadows here have been overgrown with mixed forest whose tree layer is dominated by whitebeam (Sorbus aria). Potential natural vegetation on these sites as well is altimontane beech forest. Given that both mountain ash and whitebeam only rarely form forest stands in the Julian Alps we decided to phytosociologically describe their communities. Methods Applying the Central-European phytosociological method (Braun-Blanquet 1964) we studied the pioneer forest stands of mountain ash and dwarf pine above the alp Planina Razor, under the Breginjski Stol ridge as well as grasslands and whitebeam stands under Mts. Jalovnik and Krikov Vrh (Figures 1, 2, 6, 7, 8, 9, 10 and 11). Relevés were entered into the FloVegSi database (Seliskar & al. 2003). Combined cover-abundance values were transformed into numerical values 1-9 (van der Maarel 1979). 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 Figure 1: Research area on the map of Slovenia (AL — Alpine phytogeographical region, PA — pre-Alpine phytogeographical region, SM — sub-Mediterranean phytogeograpahical region, DN — Dinaric phytogeographical region, PD — pre-Dinaric phytogeographical region, SP-sub-Pannon-ian phytogeographical region). Slika 1: Raziskovano območje na zemljevidu Slovenije. 68 O Hacquetia 15/1 • 2016, 67-91 I. Dakskobler Two new pioneer communities of Sorbus aucuparia and Sorbus aria in the southern Julian Alps Numerical comparisons were conducted with the software package SYN-TAX (Podani 2001). The relevés were arranged in three analytical tables by means of hierarchical classification. The nomenclature source for the names of vascular plants is the Mala flora Slovenije (Martinčič et al. 2007), Martinčič (2003, 2011) is the nomenclature source for the names of mosses, Suppan et al. (2000) for the names of lichens. The nomenclature sources for the names of syntaxa are Šilc & Čarni (2012), Dakskobler et al. (2013) and Zupančič (2013). Results and Discussion Sorbus aucuparia community above the alp Planina Razor and under the Breginjski Stol ridge Table 1 comprises nine relevés made under the ridge of the Breginjski Stol above the Ucja valley and at the karstified plateau (level ground) Na Polju above the alp Planina Razor (Figure 2). One of the relevés under Stol Figure 2: Localities of Sorbus aucuparia (figures 2a and 2b) and Sorbus aria (figure 8, p. 73) stands in the southern Julian Alps (western Slovenia). Slika 2: Nahajališča popisanih sestojev jerebike (sliki 2a in 2b) in mokovca (slika 8 na strani 73) v južnih Julijskih Alpah (zahodna Slovenija). Mali Sto/ TžsJ]) A 1593 Police" Njivca ® 16Ô2 . Stol u » f pfcTNa Figure 2a: Localities of Sorbus aucuparia stands under the Breginjski Stol ridge. Slika 2a: Nahajališča popisanih sestojev jerebike pod grebenom Breginjskega Stola. Figure 2b: Localities of Sorbus aucuparia stands above the alp Planina Razor. Slika 2b: Nahajališča popisanih sestojev jerebike nad pl. Razor. 68 O Hacquetia 15/1 • 2016, 67-91 I. Dakskobler Two new pioneer communities of Sorbus aucuparia and Sorbus aria in the southern Julian Alps was made above the cirque Dol at the elevation of around 1460 m and five under the ridge Puntracic-Njivca, on the location of a former pasture, at the elevation of 1540 m to 1550 m. The geological bedrock is Triassic Dachstein limestone (Buser 1986, 1987). These are potentially the sites of subalpine beech forest (Polysticho lonchitis-Fagetum) that continues into dwarf pine stands (Rhodothamno-Pinetum mugo) on the ridge. Na Polju is a rectangular level terrain at the elevation of about 1530 m, measuring 700 m x 300 m (Kunaver 1993: 38). We made three relevés here. The geological bedrock is Triassic Dachstein limestone and in the western part of the level also breccia (Buser 1986, 1987, Kunaver, ibid.). Previously occupied by pastures, this level ground is now mainly overgrown with dwarf pine stands. Especially prominent in the northwestern part of this level ground, which is also the most basin-shaped, is the Sorbus aucuparia forest, which can be seen from afar. The floristic composition of these nine relevés was compared to ten relevés of similar Sorbus aucuparia stands that were recorded under Mt. Matajur and above the upper Baca Valley and classified into the association Alno virid-is-Sorbetum aucupariae, namely into two subassociations: -luzuletosum sylvaticae on deep, slightly acid soil, and -adenostyletosum glabrae on moist stony sites (Dakskob-ler et al. 2013). We determined that these mountain ash stands are a stage in the secondary succession on potential sites of altimontane or subalpine beech forest. The succes-sional sere proceeds in the following manner: Beech forest (Ranunculo platanifolii-Fagetum, Polysticho lonchitis-Fagetum) — pasture (hay meadow) — green alder stands (Rhododendro hirsuti-Alnetum viridis, Alnetum vir-idis) — mountain ash stands (Alno viridis-Sorbetum aucupariae) — beech forest. We compared cover values of species (Figure 3) and presence or absence of species separately (Figure 4). The results indicate that relevés from Table 1(RhSa) group separately from the relevés of the association Alno viridis-Sorbetum aucupariae (AvSa) and therefore cannot be classified into this association. Three relevés of the association Alno viridis-Sorbetum aucupariae that belong to the subassociation luzuletosum sylvaticae stand out somewhat in terms of floristic composition. Similar conclusions can be made based on the synthetic table (Table 2), where we took into account the rank of the subassociation. The first two columns in this table show the composition of two subassociations of Alno viridis-Sorbetum aucupariae (AvSals = subass. luzuletosum sylvaticae;AvSaag = subass. adenostyletosum glabrae) and columns 3 and 4 comprise the relevés under the Breginjski Stol (RhSadc) and from the plateau Na Polju (RhSacv). Thess four syntaxa (columns) were 0.6- 0.5- 0.2- 0.1-0.0-I COCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCC cocococococococococococococococococow Figure 3: Dendrogram of Sorbus aucaparia communities in the southern Julian Alps (AvSa = Alno viridis-Sorbetum aucupariae; RhSa = Rhododendro hirsuti-Sorbetum aucupariae), UPGMA, similarity ratio. Slika 3: Dendrogram jerebikovih združb v južnih Julijskih Alpah (AvSa = Alno viridis-Sorbetum aucupariae; RhSa = Rhododendro hirsuti-Sorbe-tum aucupariae), UPGMA, similarity ratio. 0.7- 0.20.1-0.0-I ccccccccccccccccccccccccccccccccccccro Cf3Cf3Cf3Cf3Cf3Cf3Cf3Cf3Cf3Cf3C/3Cf3Cf3Cf3Cf3Cf3Cf3Cf3Cfi > > > > > > > > >-l=-l=-l=-l=-l=-l=-l=-l=-l= > Figure 4: Dendrogram of Sorbus aucaparia communities in the southern Julian Alps (AvSa = Alno viridis-Sorbetum aucupariae.,; RhSa = Rhododendro hirsuti-Sorbetum aucupariae), UPGMA, Jaccard. Slika 4: Dendrogram jerebikovih združb v južnih Julijskih Alpah (AvSa = Alno viridis-Sorbetum aucupariae,; RhSa = Rhododendro hirsuti-Sorbe-tum aucupariae), UPGMA, Jaccard. compared with hierarchical classification and the results are in Figure 5. Despite certain similarities — the stands of the subassociation Alno-Sorbetum luzuletosum also comprise the shrub species Sorbus chamaemespilus and in places Pinus mugo, in some spots within the stands of the subassociation Alno-Sorbetum adenostyletosum we can observe also Rhododendron hirsutum and many species of stony montane forests — it is clear that the mountain ash stands under the Breginjski Stol ridge and above the alp Planina Razor cannot be classified into the association Alno viridis-Sorbetum, in the first place because green alder does not even occur within them. The composition by 68 O Hacquetia 15/1 • 2016, 67-91 I. Dakskobler Two new pioneer communities of Sorbus aucuparia and Sorbus aria in the southern Julian Alps 0.651 - 0.60.550.5 0.45-^ 0.4-I 0.35£ 0.38 0.25-Q 0.20.150.10.05 0.0 AvSals AvSaad RhSadc RhSacv Figure 5: Dendrogram of Sorbus aucaparia communities in the southern Julian Alps (AvSals = Alno viridis-Sorbetum aucupariae luzuletosum sylvaticae, AvSaad = Alno viridis-Sorbetum aucupariae adenostyletosum glabrae; RhSadc = Rhododendro hirsuti-Sorbetum aucupariae deschamp-sietosum cespitosae; RhSacv = Rhododendro hirsuti-Sorbetum aucupariae calamagrostietosum variae), UPGMA, similarity ratio. Slika 5: Dendrogram jerebikovih združb v južnih Julijskih Alpah (AvSals = Alno viridis-Sorbetum aucupariae luzuletosum sylvaticae, AvSaad = Alno viridis-Sorbetum aucupariae adenostyletosum glabrae; RhSadc = Rhododendro hirsuti-Sorbetum aucupariae deschampsietosum cespitosae; RhSacv= Rhododendro hirsuti-Sorbetum aucupariae calamagrostietosum variae), UPGMA, similarity ratio. groups of diagnostic species (Table 3) indicates differences within subassociations rather than differences at the level of associations. In terms of proportion the researched stands (columns 3 and 4 in Table 3) are clearly dominated by species of the classes Vaccinio-Piceetea and Erico-Pinetea, so they should be classified into the class Vaccinio-Piceetea or, if considering also their physiognomy (the structure of stands), also to the class Roso pendulinae-Pinetea mugo. The successional sere is different as well and can be described as follows: Subalpine beech forest (Polysticho lonchitis-Fagetum) — pasture, grassland (Ranunculo hybridi-Caricetum sem-pervirentis) — dwarf pine stands (Rhodothamno-Pinetum mugo) — mountain ash stands (Rhododendro hirsuti-Sorbe-tum aucupariae) — subalpine beech stands. This successional sere indicates the sequence in secondary succession when a former subalpine pasture becomes overgrown through dwarf pine into a forest whose final stage will be beech. This mountain ash community is therefore classified into a new association Rhododendro hirsuti-Sorbetum aucupariae ass. nov. hoc loco. Its nomenclature type, holotypus, is relevé No. 1 in Table 1. Diagnostic species of the new association are Sorbus au- 68 O Hacquetia 15/1 • 2016, 67-91 I. Dakskobler Two new pioneer communities of Sorbus aucuparia and Sorbus aria in the southern Julian Alps cuparia subsp. aucuparia, Lycopodium annotinum, Pinus mugo, Salix waldsteiniana and Rhododendron hirsutum. The listed species well differentiate the studied community against the physiognomically similar community Alno viridis-Sorbetum aucupariae and indicate its close syndynamic relationship with dwarf pine stands from the association Rhodothamno-Pinetum mugo. However, it cannot be classified within this association as we should consider the dominant species of the highest stand layer — the tree layer, which is obviously mountain ash. The syntaxonomical rank of the subassociation Rhodothamno-Pinetum mugo sorbetosum aucupariae is therefore inappropriate in the case of mountain ash forest. For now, the new association is classified into the alliance Erico-Pinion mugo, order Junipero-Pinetalia and class Vaccinio-Piceetea. In terms of physiognomy it could also be classified into the alliance Erico-Pinion mugo, order Junipero-Pinetalia and class Roso pendulinae-Pinetea mugo. Stands under the Breginjski Stol ridge are classified into the new subassociation Rhododednro hirusti-Sorbetum aucupariae deschampsietusum cespitosae. Its differential species are Deschampsia cespitosa, Lonicera nigra, Myosotis sylvatica agg. Molopospermum peloponesiacum subsp. bauhinii, Primula elatior and Calamagrostis arundinacea. They indicate fresher sites with deeper and slightly acidic soils, as well as a certain similarity with the stands of the association Alno viridis-Sorbetum aucupariae. Its nomenclature type, holotypus, is relevé No. 1 in Table 1. Stands above the alp Planina Razor are classified into the new subassociation Rhododendro hirusti-Sorbetum aucupariae calamagrostietosum variae. Its differential species are Calamagrostis varia, Rhodothamnus chamaecistus and Horminum pyrenaicumThThey indicate stony calcareous sites in cold Alpine climate, and Horminum pyrenai-cum also a connection with former pastures. Its nomenclature type, holotypus, is relevé No. 8 in Table 1. Sorbus aria community on abandoned hay-fields under Mts. Jalovnik and Krikov Vrh Krikov Vrh is a 1298 m-high mountain in the lateral ridge of the southern Julian Alps in direction from Zabijski Kuk towards Tolminski Triglav. The parent material is mixed, dominated by platy limestone with marl and chert, and Baca dolomite with chert (Buser 1986, 1987). Its shady and partly also sunny slopes are overgrown with mon-tane-altimontane forests from the associations Homogyno sylvestris-Fagetum, Saxifrago cuneifolii-Fagetum, Fraxinio orni-Ostryetum and Amelanchiero ovalis-Pinetum mugo (Dakskobler 2002, 2014, 2015). There are some abandoned hay meadow on the shady side under the peak, and to the north of the peak there is alp Kuk (Podkuk), which is still being used as a pasture. The phytosociologi-cal composition of the pioneer Sorbus aria stand on an abandoned hay meadow under Krikov Vrh is shown in relevé 5 in Table 5. Jalovnik is a 1452 m-high mountain in the foothills of the southern Julian Alps. The shady slopes above the Kneza valley are forested with predominantly beech forests from the associations Ranunculo platanifolii-Fagetum and Homogyno sylvestris-Fagetum, only the former pastures under the peak of the mountain are now becoming overgrown with green alder (Alnus viridis). Except for the rockiest parts (dominated by the stands of the associations Ostryo-Fagetum and Fraxino orni-Ostryetum), the sunny slopes have been cleared (or burned) for pastures and hay meadows. Most of them have been abandoned for a long time. The species composition of these former hay meadows is presented in Table 4. Because of the mixed geological bedrock (limestone mixed with marlstone and chert, with the latter completely dominating some areas - Buser 1986, 1987) and slightly acid soil the character species of dry grasslands (class Festuco-Brome-tea), thermophilous forest edges (class Trifolio-Geraniet-ea) and subalpine grasslands on calcareous bedrock (class Figure 7: Stand of the subassociation Rhododendro hirsuti-Sorbetum aucupariae calamagrostietosum variae. Slika 7: Sestoj subasociacije Rhododendro hirsuti-Sorbetum aucupariae calamagrostietsoum variae. 68 O Hacquetia 15/1 • 2016, 67-91 I. Dakskobler Two new pioneer communities of Sorbus aucuparia and Sorbus aria in the southern Julian Alps Figure 8: Localities of Sorbus aria stands under Mts. Jalovnik and Krikov Vrh. Slika 8: Nahajališča sestojev mokovca pod Jalovnikom in Krikovim vrhom. Elyno-Seslerietea) are frequently accompanied by some acidophilous species from the classes Calluno-Ulicetea, Vaccinio-Piceetea and Mulgedio-Aconitetea, and order Poo alpinae-Trisetetalia. These former hay meadows are temporarily classified into the following syntaxa: Hom-ogyno alpinae-Nardetum (relevé 1 in Table 4, very similar is also relevé 2 in the same table, but for the time being it cannot be synsystematically classified), Molinio arundinaceae-Iridetum erirrhizae nom. prov., tall herbs with Iris sibirica subsp. erirrhiza (relevé 3 in Table 4), and Centaureo julici-Geranietum san-guinei nom. prov. (relevés 4 to 7 in Table 4). The presence of shrub and tree species (Rosa canina. R. glauca, R.villosa, Sorbus aria, Berberis vulgaris, Juniperus communis, Rubus idaeus, Sorbus aria and S. chamaemespilus) indicates delayed overgrowing and gradual re-establishment of the forest. In some, especially gullied parts with predominating chert and deep, slightly acid soil, former hay meadows have already become overgrown with forest (its phytosociological structure is presented in Table 5, relevés 1-4, relevé 5 represents the stand from Mt. Krikov Vrh). The tree layer of these pioneer stands is dominated by Sorbus aria, individual specimens of Sorbus aucuparia, Picea abies, Acer pseudoplatanus, Salix caprea, Betula pendula and, very rarely, also Larix decidua, Tilia platyphyllos and Fagus sylvatica. Rubus idaeus is very frequent in the shrub layer, while Calamagrostis Veratrum album subsp. Athyrium filix femina, Luzula luzuloides and Senecio ovatus frequently occur in the herb layer. These stands were recorded at the elevation between 1150 m to 1400 m, on potential sites of the altimontane beech forest from the association Ranunculo platanifolii-Fagetum and partly from the association Saxifrago cuneifolii-Fagetum (Dakskobler 2015). The successional stage with the dominating Sorbus aria in the tree layer under Mts. Jalovnik and Krikov Vrh is classified into the new association Calamagrostio arundinaceae-Sorbetum ariae ass. nov. hoc loco. Diagnostic species of the new association are Sorbus aria, Calama-grostis arundinacea, Veratrum album subsp. lobelianum, Luzula luzuloides and Convallaria majalis. They indicate a special site ecology - frequently steep, sunny and shady gullied slopes in the altimontane belt on mixed geological bedrock with dominating chert and shallow, slightly acid and fresh (dystric or eutric) brown soil, with sites gradually changing back into the beech forest. Sorbus aria is a character species of the order Quercetalia pu-and in Slovenia it occurs mainly in hop 68 O Hacquetia 15/1 • 2016, 67-91 I. Dakskobler Two new pioneer communities of Sorbus aucuparia and Sorbus aria in the southern Julian Alps Figure 9: Sorbus aria stand on the sunny slopes of Mt. Jalovnik. Slika 9: Sestoj mokovca na prisojnih pobočjih Jalovnika. Figure 10: Stand of the association Calamagrostio arundinaceae-Sorbetum ariae. Slika 10: Sestoj asociacije Calamagrostio arundinaceae-Sorbetum ariae. Figure 11: Former hay-fields on the sunny slopes of Mt. Jalovnik with Iris sibirica subsp. erirrhiza. Slika 11: Nekdanje senožeti pod Jalovnikom s taksonom Iris sibirica subsp. erirrhiza. hornbeam, beech and pine forests. The nomenclature type of the new association, holotypus, is relevé No. 2 in Table 5. The new association is classified into the alliance Sambuco-Salicion capreae, order Sambucetalia and class Rhamno-Prunetea. The studied Sorbus aria stands under Mts. Jalovnik and Krikov Vrh can still be characterised as a pioneer forest on fresh sites in the montane belt, where the tree layer is dominated by Salix caprea, Populus tremula, Betulapendula and (or) Sorbus aucuparia (Exner & Willner 2007). 68 O Hacquetia 15/1 • 2016, 67-91 I. Dakskobler Two new pioneer communities of Sorbus aucuparia and Sorbus aria in the southern Julian Alps Conclusions Stands with the tree layer dominated by Sorbus aucuparia and (or) Sorbus aria are rare in Slovenia. These two species usually occur in the lower tree layer of oak, hop-hornbeam, pine, larch, beech and (or) spruce communities. Both heliophilous pioneers can, in special site conditions in certain successional stages, dominate in the upper stand layer. We conducted a phytosociological study into two such examples from the southern Julian Alps. In the first, on former subalpine pastures on the level Na Polju above the alp Planina Razor and under the Breginjski Stol ridge, mountain ash (Sorbus aucuparia) has overgrown dwarf pine (Pinus mugo). In the second, on former hay meadows on chert under Mt. Jalovnik above the village Sela nad Podmelcem and under Mt. Krikov Vrh, turf species such as Calamagrostis arundinacea and Molinia caeru-lea subsp. arundcinacea have been overgrown by Sorbus aria. Even though such pioneer forests tend to be relatively quickly (but not earlier than in half a century) replaced by climax species, in our case beech, they should not be overlooked, especially given their protective function (protection against avalanches) as well as their role as the sites of some endemic, rare or protected species (Anon. 2002, 2004). Stands of the association Rhododendro hir-suti-Sorbetum aucupariae belong to the habitat type of Community interest 4070* Bushes with Pinus mugo and Rhododendretum hirsutum and comprise also protected or rare species such as Lycopodium annotinum,Huperzia selago, Horminum pyrenaicum, Athyrium distentifolium, Gen-tianapannonica, Cyclamenpurpurascens, Lilium martagon, and Aconitum angustifolium. Iris sibirica subsp. erirrhiza is an example of such species in the stands of the association Calamagrostio arundinaceae-Sorbetum ariae. This south-eastern-Alpine-Illyrian taxon is more frequent on former, contact hay meadows that comprise also protected or rare species and endemics like Arnica montana, Gymnadenia conopsea, Dianthus hyssopifolius, Traunsteinera globosa, Lilium martagon, L. carniolicum, Aconitum angustifolium, Platanthera bifolia, Veratrum nigrum, Rosa villosa, Helle-borus odorus and Centaurea haynaldii subsp. julica. Synsystematic classification of the studied communities into higher units is as follows: Vaccinio-Piceetea Br.-Bl. et al. 1939 em. Zupančič (1976) 1980 Junipero-Pinetalia Bo^caiu 1971 Erico-Pinion mugo Leibundgut 1948 Rhodothamno-Pinenion mugo Zupančič 2013 Rhododendro hirsuti-Sorbetum aucupariae ass. nov. Possible is also classification according to Šilc & Carni (2012): Roso pendulinae-Pinetea mugo Theurillat in Theurillat et al. 1995 Junipero-Pinetalia Bo^caiu 1971 Erico-Pinion mugo Leibundgut 1948 Rhododendro hirsuti-Sorbetum aucupariae ass. nov. Calluno-Ulicetea Br.-Bl. et Tx. ex Klika 1948 Nardetalia strictae Preising 1950 Nardo-Agrostion tenuis Sillinger 1933 Homogyno alpinae-Nardetum Mraz 1956 Festuco-Brometea Br.-Bl. & Tx. ex Soo 1947 Brometalia erecti Koch 1926 Bromion erecti Koch 1926 Centaureo julici-Geranietum sanguinei nom. prov. Molinio arundinaceae-Iridetum erirrhizae nom. prov. Rhamno-Prunetea Rivas Goday et Borja Carbonell ex Tx. 1962 Sambucetalia racemosae Oberd. ex Doing 1962 Sambuco-Salicion capreae Tx. et Neumann ex Oberd. 1957 Calamagrostio arundinaceae-Sorbetum ariae ass. nov. Povzetek Dve novi pionirski združbi drevesnih vrst Sorbus aucuparia in Sorbus aria v južnih Julijskih Alpah Sestoji, v katerih v drevesni plasti prevladujeta vrsti Sorbus aucuparia in (ali) Sorbus aria, so v Sloveniji precejšnja redkost. Navadno sta ti dve vrsti primešani v spodnji drevesni plasti hrastovih, črnogabrovih, borovih, macesnovih, bukovih in (ali) smrekovih združb. Oba svetloljubna pionirja v posebnih rastiščnih razmerah v nekaterih sukcesi-jskih stadijih lahko prevladata v zgornji sestojni plasti. Fitocenološko smo preučili dva taka primera iz južnih Julijskih Alp. V prvem, na nekdanjih visokogorskih pašnikih na potencialnih rastiščih subalpinskega bukovja (Polysti-cho lonchitis-Fagetum) na uravnavi Na polju nad pl. Razor in pod grebenom Breginjskega Stola, je jerebika (Sorbus aucuparia) prerasla rušje (Pinus mugo) in njene sestoje uvrščamo v novo asociacijo Rhododendro hirsuti-Sorbetum aucupariae. V drugem primeru, na nekdanjih senožetih na rožencu pod Jalovnikom nad Selmi nad Podmelcem in pod Krikovim vrhom pri planini Kuk (na potencialnih rastiščih altimiontanskega bukovja) pa je travno rušo vrst kot sta Calamagrostis arundinacea in Molinia caerulea 68 O Hacquetia 15/1 • 2016, 67-91 I. Dakskobler Two new pioneer communities of Sorbus aucuparia and Sorbus aria in the southern Julian Alps subsp. arundcinacea zarasel mokovec in njegova sestoje uvrščamo v novo asociacijo Calamagrostio arundinaceae--Sorbetum ariae. Kljub temu, da takšne pionirske gozdove navadno razmeroma hitro (a ne prej kot v pol stoletja) nadomesti klimaksna vrsta, v našem primeru bukev, je nanje smiselno opozoriti, predvsem zaradi varovalne vloge, ki jo opravljajo (zaščita pred snežnimi plazovi), a tudi kot rastišča nekaterih endemičnih, redkih ali zavarovanih vrst (Anon. 2002, 2004). Sestoji asociacije Rhododen-dro hirsuti-Sorbetum aucupariae sodijo v evropsko varstveno pomemben habitatni tip 4070* Ruševje z dlakavim slečem (Mugo-Rhododendretum hirsuti) in v njih uspevajo tudi zavarovane ali redke vrste, kot so Lycopodium annoti-num, Huperzia selago, Horminum pyrenaicum, Athyrium distentifolium, Gentianapannonica, Lilium martagon, Cyclamen purpurascens in Aconitum angustifolium. V sestojih asociacije Calamagrostio arundinaceae-Sorbetum ariae je taka vrsta Iris sibirica subsp. erirrhiza. Ta jugovzhodno-alpsko-ilirski takson je sicer bolj pogost na stičnih nekdanjih senožetih, na katerih rastejo tudi zavarovane ali redke vrste ter endemiti Arnica montana, Gymnadenia conopsea, Dianthus hyssopifolius, Traunsteinera globosa, Lilium martagon, L. carniolicum, Aconitum angustifolium, Platanthera bifolia, Veratrum nigrum, Rosa villosa, Helleborus odorus in Centaurea haynaldii subsp. julica. Acknowledgements Iztok Sajko prepared Figures 1, 2 and 8 for print. 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