ANNALES • Ser. hist. nal. • 12 • 2002 • t original scientific paper UDC 581,5:633.2.03(497.4-18) received: 22. 5. 2002 CONTRIBUTION TO THE KNOWLEDGE OF THE DRY GRASSLAND VEGETATION ON THE HIGHLAND AREAS OF THE POHORJE MOUNTAIN (SLOVENIA) Mitja KAUGARIČ & Sonja ŠKORNIK Department of Biology, Pedagogical Faculty, University of Maribor, SI-2000 Maribor, Koroška 160 and Institute for biodiversity studies, Science and Research Centre of the Republic of Slovenia, Koper, 51-6000 Koper, Oaribaidijeva 18 E-mail: mitja.kaligaric@uni-mb.si; sonja.skotnik@uni-mb.si ABSTRACT Collected relevés from the highland areas of Pohorje had been classified within secondary Maltgrass grasslands on acid soils (alliance Nardo-Agrostion tenuis, Nardetaiia order). Due to the nearby timber-line (nevertheless not reached on Pohorje.'!. also sub-Alpine species from natural Mattgrass stands (alliance Nardion strictae) penetrates into these grasslands. The mixture of sub-Alpine species, lowland Nardetaiia and Arrhenatheretalia species is characteristic of the association Homogyno alpinae-Nardetum Mraz /956. Association is species-poor, raffrer uniform, it varies due to the rock mess and soil humidity, eutrophisation level and shading effect. Key words: dry grasslands, silicates, Mattgrass stands, Nardo-Agrostion tenuis, Homogyno alpinae-Nardetum, Pohorje, Slovenia CONTR1BUTO ALLA CONOSCENZA DELLA VEGETAZIONE DI PASCOLI ARID I IN CIMA ALLA MONTAGNA DEL POHORJE (SLOVENIA) SINTESI I rilievi raccolti nelle aree in cima al Pohorje sono stati classificati come pascoli a nardo secondari su suolo acido (alleanza Nardo-Agrostion tenuis, ordine Nardetaiia). A causa della prossima linea boschiva (non raggiunta, tuttavia, su! Pohorje) pure specie sub-aipine di nardetei naturali (alleanza Nardion strictae) sono penetrate in tali pascoli■ La mescolanza di specie sub-alpine e di specie di pianura appartenenti a Nardetaiia e Arrhenatheretalia è caratteristica dell'associazione Homogyno alpinae-Nardetum Mráz /956. L'associazione è povera di specie, piuttosto Uniterme e varia a seconda della rocciosith, deU'umidità de! suolo, del livello di eutrofizzazione e dell'effetto ombra. Parole chía ve: pascoli aridi, silicati, nardetei, Nardo-Agrostion tenuis, Homogyno alpinae-Nardetum, Pohorje, Sfovenia 53 ANNALES • Ser. Iiist. nat. ■ 12 • 2002 • 1 Milja KAUGARIČ R Sonja ŠKORNIK: CONTRIBUTION lO THE KMOVVLfDGf OF THE DRY GRASSLAND VEGETATION ..., S3-60 INTRODUCTION It is rather interesting the fact that grassland vegetation of Pohorje, dominating mountain area in NE Slovenia, remained unexplored til! the end of 201'1 century. There are of course also exceptions, as for example forest vegetation and vegetation of raised bogs, which were investigated thoroughly by many researches (e.g. M. Wra-ber, 1953, 1954, 1955, 1956; Piskernik & Martinčič, 1970; Cenčič, 1985; Marinček, 1987; Zupančič, 1998; Culiberg & Šercelj, 2000). Regarding grasslands dominated by Nardos stricta, which occur on the top areas of Pohorje and are known as Pohorje mountain plains, we have numerous flonstic data, which are rich and variegated, however they have more historic values as to their time distance. They were summarised and enriched by Hayek (1908-1956 1923), while they were freshened up during the visit of T. VVVaber in 1970 (VVraber, 1971). The present contribution is based on the expert's report "Flora and vegetation of Pohorje plains", which was made by M. Kaligarič in 1993 (Kaligarič, 1993). Results of this report have already been summarised in the special issue of the Proteus, dedicated to Pohorje Mountains. In the year 2001 additional research of the vegetation of Matgrass grasslands were done in order to complete our knowledge about these grassland vegetation. Until now (hey were designated simply as "Mat-grass swards", which - except that in these grasslands Nardu< stricta could be found - does not tell much about this vegetation. Matgrass (Nardus stricta) is one of the commonest plants especially in the outer Alps (Ellenberg, 1996). At (he same time it is one of the most successful plants orí lime-deficient soils, not only at altitudes up to the alpine belt but also in the lower mountains of Europe and at all levels right down to the heathland areas on the plains. It avoids lime-rich soils because here it suffers from a disturbance in its nutrient balance and especially from an iron shortage (Gigon, 1971). In Slovenia Matgrass grasslands could be found in all altitudinal belts (from Prekmurje to sub-Alpine belts in Alpine region) as well as in all phytogeographi-cal regions (from sub-Mediterranean to sub-Pannonian region, if we only take the longest diagonal). The most fundamental is to distinguish between natural and semi-natural (anthropogenic) Matgrass grasslands, which could be described also by vegetation belt in which they occur. The Nardetalia Oberd. ex Preising 1949 order is present at altitudes up to the montane belt, while higher occurs the Caricetalia curvulae Br.-Bl. in Br.-Bl. et Jenny 1926 order (Elbenberg, 1996). There are several schemes used for the classification of the European Matgrass grassland vegetation. We followed the survey of Austrian plant communities (collected work "Die Pflanzengesellschaften Österreichs.") (Mucina et al., 1993; Grabherr & Mucina, 1993), where the most important surveys of European Matgrass vegetation (Prei- sing, 1949; Oberdorfer, 1957, 1978; Krahulec, 1985, 1988) are considered and critically reviewed. In Slovenia Matgrass swards were mentioned by Aichinger (1933) for Karavanke Alpine Range. The objectives of the present study were to present 1. classification of the vegetation of Pohorje Mat-grass grasslands; 2. description of its phytogeographical and ecological characteristics and 3. dynamic of the secondary succession after the abandonment. METHODS Study area Pohorje is the most dominant mountain range in the NE Slovenia. It is situated at the south-easternmost edge of the Central (non-carbonate) Alps, !t links Central Alps in the north and proceeds to the lowland sub-Pannonian region in the east (Fig. 1). The northern and the western boundaries of Pohorje Mts. are determined by Drava valley from Dravograd to Maribor and by Mislinja river, while in the east and south its limit represents the road Maribor - Slovenska Bistrica - Oplotnica - Zreče - Vitanje - Mislinja. Pohorje is therefore geographically recognizable formation, which measures 50 km in length, 30 km in width and with the area of 84.000 ha (Jež, 1995). Two geomorphological units could be distinguished, namely (1) centra! plateau, which is surrounded by peaks Klopni vrh, Žigartov vrh, Veliki and Javorskl vrh with altitudes about 1300 m and (2) the round ridge of the western Pohorje, which begins with Rogia and continues over Planinka, Jezerski vrh and Črni vrh to Velika Kopa and Mala Kopa in western direction (Jež, 1995). Especially the latter chain, which peaks exceed 1500 m, has its top areas covered by dry grasslands - the Mat-grass swards. The main characteristic of this grassland Fig. 1: Localities of the relevés of dry grasslands on the highland areas of the Pohorje Mountains. SI. 1: Lokalitete popisov suhih travišč na o vršnih predelih Pohorja. 54 ANNALES • Ser. Iiist. nat. ■ 12 • 2002 • 1 M.lf» KAUCAKIČ S Sonja ŠICORNIK; CONTRIBUTION ÎO THf KNOWLEDGE OF THE DRY GRASSLAND VEGETATION ,.„ 53-50 vegetation is acid soil as the consequence of the non-carbonate geological bedrock. Predominating are meta-morphic rocks and granodhiorythic lacolith (Hinterlech-ner-Ravnik, 1995). Gentle-sloping ridges are characteristic of the Pohorje Mountains as the result of the old geological formations on the top areas. Parts with bare surface and exposed rocks are only rarely to seen. The study area lias the montane climate. The average temperature in the coldest month is below -3'C and in the warmest month above 10"C. Such conditions are characteristic of altitudes between 1500 and 2000 m a.s.i. Sampling methods and data analysis In the years 1993 and 2001 32 phytosociologicai relevés of dry grassland stands on the top areas of Pohorje Mountains were collected (Fig. 1 ). They were compiled using standard procedure of the Brauri-8Sanquet approach (Braun-Blanquet, 1964; Westhoff & van der Maarei, 1973; Dierschke, 1994). All relevés were saved in the computer data base using program JODI 97 (Petersen et a!., unpbl.). For the classification procedure Two-Way-!Ndlcator-SPecies ANafysis (TWINSPAN; Hill, 1979) was chosen, it was run using computer program VEGI SReiter, 1998). Ecological conditions of the stands were estimated by i;!lenberg indicator values (Ellenberg et al., 1991} for light, temperature, soii moisture, pH and nitrogen content. ft should be noted that Ellenberg's N-value should be interpreted as a general indication of fertility, rather than as an index of nitrogen availability {Ellenberg et al., 1991). For each relevé, indicator values were averaged over all species using species abundance as weight. Geo-elements were determined according to Poldini (1991). Nomenclature Taxonomic nomenclature follows Martinčič et al. (1999), syntaxonomic nomenclature follows Mucina et ai (1993) and Grabherr & Mucina (1993). RESULTS AND DJSSCUSiON Vegetation classification The basic dilemma, whether Matgrass swards of Pohorje belong to the natural sub-Alpine grasslands above the forest fine, or to the secondary Matgrass grasslands beiow the forest line, seemed to be solved easily. Pohorje doesn't reach the forest line, although its fop areas free from trees and with single plant species of subAlpine and Alpine belts have "subalpine" aspect (habitus). Some of those species belong to the class of the alpine acid-soil swards Cancetalia curvulae. However, their portion' is too low and considering the floristic principle this reievés should be classified within the class of the Matgrass grasslands and dwarf shrub heaths Calluno-Ulicetea, namely to the Nardetalia order, which includes the lowland dry Matgrass swards. Additional confirmation of this classification is also slow but persistent spontaneous reforestation of studied Matgrass swards. Vegetation of Nardetalia order is spread mostly in Atlantic and sub-Atlantic Europe including Alpine region (Preising, 1949). While the lime-defic:ient substrates are characteristic of the larger part of the Europe where great part of the semi-natural pastures and meadows belong to that order, in Slovenia due to the prevailing calcareous bedrock, such dry pastures and meadows are not very frequent. Within Nardetalia order two more xe-rophilous alliances can be distinguished. The Matgrass swards could be therefore classified within (a) the alliance of the lowland and montane Matgrass swards Violion caninas Scwickerath 1944 or (b) within the alliance Nardo-Agrostion tenuis Sillinger 1933, which is spread mostly in the Carpathian Mountains and reaches also the edges of the Alps (Ellmauer, 1993). A central position within the Violion caninas has the Polygalo-Nardetum association. It. is mainly found on very acid and nutrients poor soils from the lowland up to the altitudes about 1300 m a.s.l. arid contains also sporadic alpine species (Steinbuch, 1995). Regarding bioproduction and species-richness these grasslands are richer and include more species of lowland intensive grasslands lArrhenatherion alliance) than Matgrass swards of Pohorje. The latter are in general floristically poorer, but at the same time they are characterised by many species (e.g. Gentians pannonica, Potent ilia aurea, Solidago vir-gaurea, Hieradum aurantiacum, ieontodon helvéticas, Pseudorchis albida and Hypochoeris uniflora), which do riot appear in the Polygalo-Nardetum association. All this facts indicate that the dry grasslands from Pohorje can be assigned to the Nardo-Agrostion tenuis alliance, which is typical for montane belt. Our analyses and comparisons with similar dry grassland stands from nearby Alpine region in south-eastern Austria (Steinbuch, 1995) confirmed, that within that alliance we can classify them in the association Homo-gyno a Ip inae-Na rde tun i Mráz 1956. In the study made by Steinbuch (1995) has also been reported about one high-altitude variant of the lowland association Polygalo-Nardetum gymnadenietosum, namely variant with the species Homogyne alpina, which at the higher altitudes passes directly into the Homogyno-Nardetum association, In such conditions it must be sometimes difficult to determine a boundary between both associations. This however is not the case in our study area: Pohorje plains are closed ecosystems, isolated on their altitudes and separated from lowland grasslands by large forests. Releves are presented in Tab. 1. Sequence of the reievés is according to the TWiNSPAN analysis. Diag- 55 ANNALÉ5 - Ser. hist. nal. • U ■ 2002 • t Milja KALlCARIC & Soup SKORNIK. CONTKIUUTIOM TO THE KNOWtíDGE OF THE DRV GRASSLAND VEGETATION .... 53-60 Tab. 1: Analytical table of the Homogvno alpinae-Nardctum Mraz 1956 association. Tab. 1: Analitična tabela asociacije Homogyno alpinae-Nardctum Mraz 1956. Relevé number Altitude (m a.s.l.) SlopeO Aspect Cover (X) Plot surf-lie (s<|.m) Number oi spcties 1 2 3 4 5 t j 7 B 9 10 II 12 II <4 IS 16 17 18 19 HOP (SCO 1?S0 S>«3 Í3CO l.lttjlSZD USO IS23 1436 SSilU »ISO MIO UtS 1-lbO M65 lir-C I<00 tí O S 1(1 2 3 !!5 5 ID S I 3 D 111 5 J 3 20 2 S / SW SW 5 swi E 5W W W SW NW / S W / S SW SW 9S 100101)'» 70 SO jlOO 100 100 too 100 90 100 100 100 100 10O 100 90 SO SO SÚ SO 25 sol 50 50 50 SO 25 ?S '-"> 25 25 SO 25 25 75 14 16 15 13 12 H j 16 I» n 13 15 22 1? 13 1& tč 2! 13 20 21 22 23 24 2S 26 MÍO H75 W3C 5.S3C HB" 15IO .3 S 3 3 i J 3 S S SW SW MW SW Nt 27 28 29 Kl 31 32 vt.. Ufirl i<;w> i JSI> »J5-1 Urin is 0 0 0 20 VV t 1 I / i 90 80 100100100 100100."00 100100 inn 100100 2S 2S 25 1S 15 15 K 25 25 13 12 Ii 50 50 50 SO SO 23 13 IS 19 ib IS 25 Ft% p Diagnostic species of (he association Solidago virgaurea •".... Voratnim alttim siAisp. . album VP Homogyoe alpina + CC liypochoeris uniflora + + + CC Centiana pannonica .... CC Poicnlilli! antea + A,O NardoAcro*lion tenuis Silfinger 1933, Nardelalia Oberd. ex Preising 1949 Narfltm stricte 3 1 ) 1 * Arnica montana * + 1 * Hteracium auratitia- ..-».. aim /•fyjMririWJ perforatum..... CU Catluno-Ulicctca lír.-RI, et R. Tx. ex Klika ct Had.ií 1944 Polentilfo erecta + Calinita vulgaris <1 2 Inzuía camptsttin < * Carex pilulihta Antennaria dioica * AntlKixanthítm oc/cra-htm Botrychium lunaria f'olyga/a vulgaris Phyieuma spic aturo CC Cjríccfca lunuÍM Br-Bl. 1948 Campanula barbaia + + * * * >■ leontodon belvettcus * * * •>• PnnitJotríUs alinda +..... MA Molinio-ArrfienaIherelea R. Tx. 1937 em. R. Tx. 1970 Festuca rubra agg Lychnis ilos-cuculi Desc.harnpsia caespi-tosa Cruciate glabra Agrostis capilla! is Leucamhenttim vulgare Ranunculus actis Molinia caerulea Euphrasia strict» 1 1 4 3 4 1 2 1 1 , 1 3? II! 50 II! 47 III 2Í II 22 II 3 I 3 100 V : 17 v . 20 ¡I * 13 ÍI 1 100 V 2 "8 V . 41 111 i- 34 !l 4- 2S ¡I E 15 t i 75 IV 47 III 13 1 4 4 . ) i i 4 2 3 4 4 2 2 I 50 III + i 4 4 4 •t -i. * * * 38 II 1 ■j 2 1 2 16 1 4 + + 13 1 <¡ i * + 9 4 4- + 9 6 I 4 + ft 1 + + 2 2 1 1 4 + + + 4 4 » t 1 1 2 4 7 + ¡V 4 4 1 4 + + 4 4 4 ■b 4 2 44 ill 1 4 + + 4 * 2 1 1 * t + 41 111 •fr + + 1 4 + 1 + 4 t 4 ¿ 1 4 2 1 4 1 t 1 ■1 75 IV 4 2 2 2 + 4 •Í- I 4 1 2 4 4 2 2 ■Í 66 IV - : 2 n 2 + 2 2 2 1 2 4 4 3 3 2 j 2 1 63 IV -f- 4 4 4 -t + 4 4 r 44 111 4 4 4 4 \ ? 4 J 41 III 1 + 1 + + 4 i - 30 II 4 4 + * 4 4 19 + 4 19 1 13 -t 6 I. 4 6 t 6 ! + 6 1 + 2 16 i 6 i Vaccintutw vitis-idaea Lu/ula pih-.ii lu/itla luzuloides S Other species Melampyrinn prateose Vvji r tnitmi myiUllus Avenelh flexuosa Gymtwdtjtv'a conopsea 1 lieraclum laevicttlae lunula sylvatica Anomone ttvtnorosa Gentian* ctticiata Crocus napoliiamjs TeucritHn chanuedrys Hypericum vionlanum Stellaria granting Rhinanlhus ptiklter Veronica chamacdrys UCIKNS: Cladonia spp. Ceuatia island'ca Locations and sporadic taxa (lokacijo in posamezne vrsle): 1 - slope of Veliki Črni vrh; 2 ■ between Mali Čmi vrh and Veliki Črni vrli, l.ycopodium ctavatum; 3 . Veliki črtti vrli - OtiSe; A ■ slop<.> of Velika Kupa; S - V. Črni vili; 6 - V. Črrii vrh; 7 - Mali Črni vrh; 8 - Čmi vrh - Oliše; 9 - Mulejev vrfi; 10 - Konjiška plitnja; 11 - flaoinka; t2 - Jezerski vrh; 13 - Oslruščica; 14 - OliSe; IS - RibmJka koča; 16 - Mali Oni vrh; 17 - Oiluiščiai; 18 - Veliko sedlo, Pungart; 19 • Otise-V. Črni vrh; 20 • Oslrnščica; 21 - Ostrošfica-Rogla, Molinia *twxltiwcea, Carex pattescens; 21 - Plxninks; 23 - Planinka, 24 - Gslrušiica; 25 - Oslrn?tica; 26 - iezcrski vrh; 27 .. OsliuSčica, Bteclmum spicant; 2« • Konjiška planja, tup/irsjra rc&ikoviana, Oanlhonia decumbens; 29 - Ribniška koia, Ceraslium gtonmahnn, Ranunculus platanifolius; 30 - Oliše - saddle of Pongarl, Tri-toltwn repens, Hieracium pilosc-lla; 31 - ai liiefoot of Osiruiiica; 32-Velika Kopa-Oliše, Cari/na acaulis. TriioHumpralense. Legend (legenda): VP - VaccMo-Piceerea, CC - Carttctex citrvulae 56 ANN Alf S • Scr. his!, rial. • 12 • 2002 • 1 Milj,» KAUGARir S Sonja SKORNIK: CONTRIBUTION TO THE KNOWLEDGE OH THE DRY CRAS51ANIJ VEGETATION .... 53.6O nostic species of the association as well as the species of the class and alliance are well represented, considering that this are species-poor grasslands. In sampled relevés some species of the classes Caricetea cutvulac and Mo-linio-Airhenatheretea are present. Because of the nearby forest and spontaneous reforestation also a larger proportion of forest species is present. Fforistic composition Four clusters of relevés were separated by TWINS-PAN classification. The first 6 relevés represent the most dry and species-poor variant of Pohorje Matgrass swards, ft is characterised by high cover of Calluna vulgaris, which gives to this grassland formation special physiognomic character. This stands are rich also in some others dwarf-shrubs, namely in Vaccinkim vitis-idaea and/or V. myrtiflus. According to some authors (e.g. Horvat er ai., 1974) they were named also as "Nardo-CaHunetum", which was a derivative of the wide interpreted association "Amico-Nardetum". Those grasslands however do not represent a separate association, but are parts of different Matgrass communities of different vegetation belts and phytogeographical regions. Heaths with Calluna vulgaris occur on very shallow soil, poor with minerals and with low pH values. These stands have often parts with bare surface and are more often exposed to erosion (inclination!) than typical variants of the association which predominately occur on flat ground. Relatively high is the proportion of lichens. Dominant are Cetraria islandica and different Cladonia species. Relevés from 7 to 19 represent the most "typical" form of the Hornogyrio-Naidetuni association. These stands are found on the gentle sloping ridges of the tops of Pohorje; from Voiovica over Rogla, Mulejev vrh and Planinka; from Ribniško Pohorje over Črni vrh, Pungart to Mala Kopa and Velika Kopa. Species characteristic of this "central" variant are Arnica montana, Vera trum album subsp. album, Homogyne alpina, Gentiana pan-nonica, Carex pUulifera, Hteracium aurantiacum, Fe$-tuca rubra and Leontodon heiveticus. Only occasionally also Hypochoeris un i flora and Poteniilia aurea could be found. According to some historical data (Petkovšek, 1952) also Gentiana acaulis appears on Pohorje Mts. We could expect it also in this type of grassland stands unless it was found in lower altitude (at Pesnik) (Petkovšek, 1952; T. Wraber, 1967, oral communication). Since these stands are in the stage of slow spontaneous reforestation, it is possible, that Gentiana acaulis, because of the successful competition of (ungrazed) grass species, has firstly regressed and finally disappeared from Pohorje. Characteristic species of these Matgrass swards and specially those on higher altitudes is also Rhinanthus pulcher. Cluster with relevés from 27 to 32 represent more eutrophic (mesophile) variant of Matgrass swards, char- acteristic of saddles, flat plains and even small hollow depressions when they are not too moist. Soil is deeper and richer with nutrients. Such grasslands are also of major economic value. They are used as meadows and pastures. Larger is the proportion of the Molinio-Arrhenatheretea species (Tab. 1}, such as Festuca rubra agg., Deschampsia caespitosa. Lychnis flos-cuculi, Cruciate glabra, Ranunculus achs etc. Releves from 20 to 26 are transitional forms from typical to the grasslands with higher eutrophication level. Matgrass grasslands can also become marshy. Acid soil and additional acidification due to the water stagnation lead to the appearance of species of raised bogs and intermediate mires of the classes Oxycocco-Sphagnetea and Scheuchzerio-Caricetea fuscae. First Molinia caerulea begins to dominate. These stages in which still some Matgrass grasslands species could be found, become floristically poorer. Nardus striata slowly gives way to mesophilous Carex and grass species fa. Carex canescens, C. pilulitera, Oanthonia decumbens) and shortly afterwards Eriophorum angustifolium and £ vaginatum become dominant. Some authors (e.g. Wagner, 1954; Flfmauer, 1993) classify such intermediate stages still within the Matgrass swards. However, they present the separate atlantic alliance Nardo-Juncion squarrosi (Oberd. 1957) Passarge 1964. Our opinion is that such vegetation formation are already outside of grassland vegetation: Nardus strict* remains because of its tolerance of the humidity and acidity. Releves of such stands were therefore not placed within vegetation discussed in these study. Geo-elements The chorological structure of the association (Fig. 2) with the absence of lllyriari species and with the high portion of European (including Alpine) geo-elements confirms geographical position of Pohorje Matgrass swards at the easternmost edge of the Central Alps. Almost one third of the species represent Circumboreal, Arctic-Alpine and Alpine geo-elements. Second third represent Eurasian, European arid Eurosiberian geo-elements and the rest Mediterranean-Montane, Eu-rimediterranean and Cosmopolite species. Ecological conditions Ellenherg indicator values Ecological conditions of the stands v/ere estimated by Ellenberg indicator values (Ellenberg etat., 1991) for light, temperature, soil moisture, pH and nitrogen content (Fig. 3). Mean values of weighted averages were calculated for each group (cluster) of releves: (I) heath, (2) typical stands, (3) transitional stands between (2) and (4), (4) relatively eutrophic stands. 57 ANNALES • Ser. hist. nat. • 12 • 2002 - 1 Milj» KALIOA8IC & Sonja SkOKNIK: CONtRIBUtlOKl TO THE KNOWLEOGI: of THE DRV GRASSLAND VEGETATION .... 5340 ■ ) Europea;» (evropske) 17% Xv CurOfiberían fevrosibirske) 9% Eurasian ievtazijske) 7 7% Alpine Iztp'mske} 4% ffiffl Circumboreal icirfcumboToalrH!) ?t% [111 Mcdilerr.-Montane (mecfiieransko-monsariske) 11% 'y's/^ Etiriroeditefrancar» ttrvrimedili-ranslcei 9% Ccjsmfiolitans fko;tmopolitiwi 9% [ | Arciic-Alpinc (.vkliino-alpTiikej 4% Fig. 2: Chorological groups of the association Homo-gyno alpinae-Nardelum in the area of Pohorje. SI. 2: Geoelementna sestava asociacije Homogyno alpi-nae-Nardetum na ohmocju Pohorja. The Ellenberg light-values show, that in all stands heliophilous grasslands species are predominating. Apart from altitudinaf levels we deal with species of open and sunny habitats. Indicator values for temperature show gradient from releves of heaths ¡the lowest value) to eutrophic stands (the highest value), which we interpret with the- occurrence of sporadic. suh-Alpin species in heaths and in typical formation. In the eutrophic stands also some species of lowland intensive-used grasslands are present. Humidity doesn't vary much; the lowest value was calculated for heath and the highest for eutrophic stands, with deeper and therefore more humid and nutrients-rich soil. Ellenberg reaction values clearly show acidophilus character of studied Matgrass swards. According to the species, soil reaction is the lowest in heaths and the highest in eutrophic stands. Also soil fertility does not differ much between clusters. However heath stands appeared to be less fertile than others. Spontaneous reforestation of Pohorje plains Matgrass grasslands of Pohorje have a semi-natural origin, i.e. Ihey had been developed and are maintained because of the human activities. Due to the changes in traditional land-use, most plains of Pohorje are no longer used for grazing and mowing and are increasingly being regrown by trees. The natural reforestation process is relatively slow and could be noticed throughout a longer period. Main factors which slow down this secondary succession are: 1. short vegetation season due to the Light Nutrients TenipsraCurti Moisture pH □ Typical stands ID Transitional stands □ Eutrophic stands Fig. 3: Mean values of weighted averages of Ellenberg indicator values for four (4) groups (clusters) of relevés of Homogyno alpinae-Nardetum association. SI. 3: Povprečje tehtanih (ponderiranih) srednjih vrednosti Ellenbergovih indeksov za štiri skupine (klastre) popisov asociacije Homogyno alpinae-Nardetum. montane climate; 2. absence of the shrubs, which generally play important role in the process of reforestation; 3. acid soil causes lower species-richness than lime-rich soil - lower species-richness has negative influence on the secondary succession; and 4. absence of invasive Umbelliferous species (e.g. Laserpitium siler, i. lalifo-lium on limestone), which in many cases become competitive since the removal of man's influence. However, the process of spontaneous reforestation is making progress. A determining role play favourable edaphic conditions, e.g. in small depressions and on the slopes with deeper soil which has more water-holding capacity. In such stands Carex brizoides, which is otherwise typical for wet lowland forests, becomes absolutely dominant and can form pure stands. Carex brizoides become very invasive species, which overgrows other smaller plants and is spreading by rhizomes. Moisture and shade are favourable ecological conditions, which comes with its invasion. We can often observe how the isolated tree or group of trees in the middle of plains represent nucleus of spontaneous reforestation (Kaligaric, 199.5). When the reforestation process starts with Carex brizoides stages, not concentric, but asymmetric patches are formed, due to the fact that there is more sedge on the shady than on the sunny site of the trees. Stands with Carex brizoides are very species-poor - heliophilous grassland species are reduced, while the penetration of forest species is very slow. At the same time two woody species appear -spruce (Picea abies) and mountain ash (Sorbus aucu-paria), and also sporadic forest species of the herbaceous layer: Anemone nemorosa, Solidago virgaurea, 58 ANNALES • Ser. Iiist. nat. ■ 12 • 2002 • 1 ■Milja kÄLtiÄKC & Sonja STORNI*: CONTRIBUTION XO THE K NOW ILO« Of THE DRY GRASSLAND V£GtTATiOM .. . f,J-00 PolygonMxim multiflorum, etc. However the sedge is not always the first coloniser of the fallow plains. On dry places first spruce or mountain ash start to germinate. They change microclimate by giving shadow and enable enlarging of the nucleus of reforestation (Kaligarif, 1995). Very successful is also spreading of already existent forest. Its frontal part slowly approaches the grassland centre and narrows its area. The smaller is grassland area the greater is effect of forest on the microclimate. The solar radiation is now converted at the level of the woodland canopy and cannot reach the lower growing plants. Decisive influences have higher humidity and lower temperatures in summer time. Many helio- and thermophilous herbaceous plants are being suppressed by dwarf-shrubs like Vaccinium myitillus on dry and Carex brizoides on humid sites. PRISPEVEK K POZNAVANJU VEGETACIJE SUHIH TRAVIŠČ OVRŠNIH PREDELOV POHORJA (SLOVENIJA) Mitja KAUGARIČ & Sonja ŠKORNtK Oddelek za biologijo, Pedagoška fakulteta, 51-2000 Maribor, Koroška ! G0 in Inštitut za biodiverzitetne študije, Znanstvene raziskovalno središče Republike Slovenije Koper, SI-6000 Koper, Garibaldijeva !8 E-maik mitja.kaligarEc@yni-mb.sr; sonja.skornik@uni-iTib.si POVZETEK Avtorja sta vzorčila sestoje suhih travišč - planj in res a v na ovršnih predelih Pohorja po standardni Braun-Blanquetovi metodi. Ugotovila sta, da so travišča na najvišjih predelih precej uniformna, floristično skromna in da se počasi zaraščajo. Travišča pripadajo redu sekundarnih travišč na silikalih Nardetalia Oberd. ex Preising 1949, zvezi voikovij Nardo-Agrostion tenuis Sillinger 1933. Ker so (a travišča že blizu gozdne meje (ki na Pohorju sicer ni dosežena) segajo vanje (udi vrste iz naravnih subalpinskih voikovij (zveza Nardion, razred Caricetea curvuiae). Tako tvorijo mešanico z izrazito subalpinskim vplivom in hkrati prevladujočim kontingentom nižinskih nardetalnih in arenateretalnih vrst, kar smo - poleg nadmorske višine, ki ne dosega gozdne meje - upoštevali tudi pri uvrstitvi. Ugotovili smo asociacijo Homogyno alpinae-Nardetum Mraz 1956, ki je po vsem ovrinem delu Pohorja precej enotna, variira pa glede na talne razmere, zasenčenost in stopnjo evtrofiziranosti. Na plitkih tleh z razgaljeno matično kamnino je floristična sestava skromnejša. V večji meri sc pojavljajo vrste Calluna vulgaris, Antennaria dioica, lišaji (npr, Cetraria islandica in vrste rodu Cladonia spp.j, ind. Ta tip vegetacije je poznan pod imenom pohorske resave. V zasenčenih legah se pojavljajo gozdne vrste in Carex brizoides, v bolj evtrofiziranih razmerah pa are-natetetalne vrste. Asociacija je optimalno razvita na sončnih, suhih rastiščih z rahlim naklonom. Geoelementna sestava z odsotnostjo ilirskih vrst in s prisotnostjo evropskih elementov, vključno z alpinskim, potrjuje lego pohorskih planj na zadnjem jV odseku Centralnih Alp. Sinekološke značilnosti obravnavane vegetacije smo ocenjevali z Ellenbergovimi indeksi za svetlobo, temperaturo, vlažnost, pH in hranilnost. Indeks za svetlobo kaže, da na teh traviščih prevladujejo heliofilne vrste. Medtem ko so najbolj topla, vlažna ter z najvišjim pH rastišča bolj evtrofiziranih sestojev, so najbolj zakisana in s hranilnimi snovmi siromašna rastišča resav. Zaradi opustitve paše oziroma košnje se velik del pohorskih planj zarašča z gozdom. Zaraščanje je sicer počasnejše v primerjavi s tistim iz nižin ali na apnencu vendar kljub temu napreduje. Razlikujemo več tipov zaraščanja: (?) na tleh z več vlage poteka zaraščanje z migaličnim šašom