HACQUETIA 5/1 • 2006, 73–112 CALCAREOUS OPEN SEDGE SWARDS AND STONY GRASSLANDS (SESLERIETALIA CAERULEAE) ON THE NORTHERN EDGE OF THE TRNOVSKI GOZD PLATEAU (THE DINARIC MOUNTAINS, WESTERN SLOVENIA) Igor DAKSKOBLER* Abstract Applying the standard Central-European phytosociological method we studied the open sedge swards and stony grasslands on the northern edge of the Trnovski gozd plateau in western Slovenia. Based on extensive compari- sons with similar communities in the Southeastern Alps and in the northern part of the Dinaric mountains we classified the studied communities into the order Seslerietalia caeruleae Br.-Bl. in Br.-Bl. & Jenny 1926. They are differentiated from similar communities in the Southeastern Alps by certain northern-Illyrian endemics (above all by Primula carniolica and Hladnikia pastinacifolia) and by some of the southern or southeastern-Alpine-Illyrian species (e.g. Phyteuma scheuchzeri subsp. columnae, Astrantia carniolica and Aquilegia bertolonii). This article describes these communites as the following new syntaxa: Primulo carniolicae-Seslerietum calcariae, Primulo carniolicae-Carice- tum firmae, Caricetum mucronatae var. geogr. Primula carniolica and Caricetum ferrugineae var. Astrantia carniolica. Key words: Caricion firmae, Caricion austroalpinae, Caricion ferrugineae, phytogeography, phytosociology, syntax- onomy, the Trnovski gozd plateau, Slovenia Izvleček Po standardni srednjeevropski fitocenološki metodi smo preučili blazinasto rastje in kamnita travišča na se- vernem robu Trnovskega gozda v zahodni Sloveniji. Na podlagi obsežnih primerjav s podobnimi združbami v Jugovzhodnih Alpah in v severnem delu Dinarskega gorstva preučene združbe uvrščamo v red Seslerietalia caeruleae Br.-Bl. in Br.-Bl. & Jenny 1926. Od podobnih združb v Jugovzhodnih Alpah jih razlikujejo nekateri severnoilirski endemiti (predvsem Primula carniolica in Hladnikia pastinacifolia) in nekatere južno- oz. jugo- vzhodnoalpsko-ilirske vrste (npr. Phyteuma scheuchzeri subsp. columnae, Astrantia carniolica in Aquilegia bertolonii) in jih opisujemo kot naslednje nove sintaksone: Primulo carniolicae-Seslerietum calcariae, Primulo carniolicae-Carice- tum firmae, Caricetum mucronatae var. geogr. Primula carniolica in Caricetum ferrugineae var. Astrantia carniolica. Ključne besede: Caricion firmae, Caricion austroalpinae, Caricion ferrugineae, fitogeografija, fitocenologija, sinta- ksonomija, Trnovski gozd, Slovenija 1. INTRODUCTION a rich, several centuries long tradition of planned forest management (comp. for example Mikuletič The Trnovski gozd plateau is a vast high karst pla- 1953, 1985, Kozorog & al. 1998, Žigon 2003). The teau in the northwesternmost part of the Dinaric forest and scrub vegetation of this region was inves- mountains. Habič (1968) and Janež & al. (1997) tigated by M. Wraber (1953, 1952, 1962), Piskernik among others, contributed a detailed geomorpho- (1954, 1973, 1991), Martinčič (1977), Marinček & logical description of the plateau, whose largest al. (1977), Čampa (1978), Puncer (1979), Urbančič part is covered with expansive forests and which has & al. (1979), Zupančič (1980, 1999), Hočevar & al. * Institute of Biology, Scientific Research Centre of the Slovenian Acadamy of Sciences and Arts, Regional unit Tolmin, Brunov drevored 13, SI - 5220 Tolmin, [email protected] 73 HHQ_5-1.inddQ_5-1.indd 7373 226.7.20066.7.2006 110:23:230:23:23 HACQUETIA 5/1 • 2006, 73–112 (1995), Marinček (1996, 1998), Dakskobler (1998, edges and rock walls of Stanov rob, Poldanovec and 1999, 2003 a), Dakskobler & al. (2000), Urbančič Zeleni rob, as well as on Sončni rob above Hudo & Dakskobler (2003), Surina (2001, 2002), P. Košir polje, in Gamsarica above the spring of the Belca (2004, 2005), Zupančič & al. (2005) and others. and under Hudournik on the northern edge of the There are fewer publications on non-forest veg- Vojsko plateau above the valleys of Hotenja and etation. Petrophilous vegetation and stony grass- Kanomlja (Figures 1 a and 1 b). lands on the southern edge of the Trnovski gozd plateau were studied by Poldini (1978), Kaligarič (1997) and Kaligarič & Poldini (1997). Some data on the vegetation and typical communities of the northern edge of the Trnovski gozd plateau were contributed already by Martinčič (1958, 1961), and some of the chasmophytic communities and stony grassland communities were described in more de- tail several years ago (Dakskobler 1998). General synoptic descriptions of flora and veg- etation of the Trnovski gozd plateau were contrib- uted by T. Wraber (1959, 1990 a), T. Wraber & Zupančič (1999), Velikonja (2001) and Dakskobler (2004). The reasearches conducted on the vegetation Figure 1 a: Localities of the researched stony grasslands on of the northern edge of the Trnovski gozd plateau the map of Slovenia. so far (Dakskobler 1998, 1999) were supplemented Slika 1 a: Nahajališča popisanih kamnitih travišč na karti with relevés of calcareous open sedge swards and Slovenije. stony grasslands found on smaller surfaces on rocky Figure 1 b: Localities of the researched stony grasslands (Source: Map of Slovenia 1: 250 000, GURS). Slika 1 b: Nahajališča popisanih kamnitih travišč (Vir: Pregledni zemljevid Slovenije 1: 250 000, GURS). 74 HHQ_5-1.inddQ_5-1.indd 7474 226.7.20066.7.2006 110:23:230:23:23 IGOR DAKSKOBLER: CALCAREOUS OPEN SEDGE SWARDS AND STONY GRASSLANDS (SESLERIETALIA CAERULEAE) ON THE N. EDGE OF THE TRNOVSKI GOZD … 2. METHODS Grabherr & al. (1993), Robič & Accetto (2001), Theurillat in Aeschimann & al. (2004 b), Surina & Between 1996 and 2004 we made 52 relevés of al. (2004) and Surina & Dakskobler (2005). stony grasslands and sedge swards in the rock walls on the northern edge of the Trnovski gozd plateau applying the standard Central-European phytoso- 3. ECOLOGICAL ciological method (Braun-Blanquet 1964). The collected relevés were entered into the FloVegSi CHARACTERIZATION OF THE database (Fauna, Flora, Vegetation and Paleoveg- RESEARCH AREA etation of Slovenia) of Jovan Hadži Institute of Bi- ology SRC SASA (T. Seliškar & al. 2003) and ana- On its northeastern edge, the Trnovski gozd pla- lysed with methods of hierarchical classification teau falls extremely steeply into the Trebuša valley. and the ordination method of principal coordi- The collective name for the rocky and precipice nates analysis (PCoA). We employed the SYN-TAX slopes of Stanov rob (1191 m), Poldanovec (1299 2000 (Podani 2001) program package. Combined m) and Zeleni rob, which are all cut with numer- cover-abundance values were transformed into the ous gorges, is Govci (also known as Golci, and the ordinal scale following van der Maarel (1979). In rockiest part under Poldanovec and Zeleni rob as our comparisons we tested the following methods Trebuška stena). The geological bedrock is Trias- of hierarchical clustering: “complete linkage (far- sic dolomite (Buser 1965, 1973 a, b, 1986, 1987). thest neighbour) method – FNC”, “(Unweighted) The soil is shallow, extremely skeletal (Lithosols, average linkage method – UPGMA”, “(Weighted) rendzina, colluvial-delluvial soil in gullies) and average linkage method – WPGMA”, as well as subject to erosion. The northeastern part of the “Incremental sum of squares – MISSQ” method Trnovski gozd plateau has a relatively cold and very and ordination method of principal coordinates humid mountain climate. The nearest meteorolog- analysis (PCoA). We used the dissimilarity coeffi- ical observatory on Vojsko (1070 m a.s.l.) reported cient “1- similarity ratio”. Podani (2005) questions the mean annual temperature of 6.2 °C in the pe- the correctness of applying these methods when riod between 1961–1990 (the mean temperature processing ordinal data (such as the combined of the coldest month, at that time January, was cover-abundance values transformed with van der –2.8 °C, and the mean temperature of the warmest Maarel's scale from 1 to 9) and proposes instead month, July, was 15.3 °C – according to Mekinda- Ordinal Clustering (OrdClAn) and Non-metric Majaron 1995: 129). The mean annual precipita- Multidimensional Scaling (NMDS) for such data. tion in the same period (1961–1990) on Vojsko was We therefore tested these two methods as well and 2450 mm. Precipitation is relatively evenly distrib- the results turned out to be very similar. The results uted throughout the year with autumn months be- of numerical methods were combined with the clas- ing the wettest, whereas the lowest amount of pre- sic arrangement based on diagnostic species. Some cipitation is usually recorded in the second half of of the determined communities were compared winter, in early spring and in summer (B. Zupančič with similar communities in the Southeastern Alps 1995: 339). The snow stays in deep gorges under and in the Dinaric mountains. The results of this Poldanovec and Zeleni rob long into the spring. In extensive comparison (Surina & Dakskobler 2005, this part of the Trnovski gozd plateau, sleet is a very Surina & T. Wraber 2005, see also Surina 2005 a) common weather phenomenon, occasionally also were the starting point for our description of new whirlwinds. Northern winds are very powerful on syntaxa. When calculating the proportions of diag- ridges and exposed edges. Also common are forest nostic species we used as weight (ponder) not only fires, which usually affect dry and exposed jags and frequency, but also the cover index (Ic) – Lausi & ridges, at least partly overgrown with dwarf pine al. (1982: 124). (Pinus mugo) and (or) natural Austrian pine (Pinus The nomenclature follows the