ANIMALES • Ser. hist. nat. -12- 2002 • 2 original scientific paper UDC 582.542(497.4) received: 2002-11-05 RELATION BETWEEN ENVIRONMENTAL VARIABLES, SPECIES RICHNESS AND SPECIES COMPOSITION OF SLOVENIAN SEMI-DRY MEADOWS OF MESOBROMION ERECT! ALLIANCE Sonja ¡KORNIK & Mitja KAUGARiC Biology Department, ¡-acuity of Education, University of Maribor, Sl-2000 Marsbor, Koroîka 1 GO and Institute of Biodiversity Studies, Science and Research Centre of the Republic of Slovenia, Koper, SI-6000 Koper, Caribaldijeva 18 E-mail: sonja.skomik@uni-mb.si ABSTRACT Semi-dry meadows of the Central European alliance Mesobromion erecti (class Fesluco-Brametea) are habitats with high biodiversity. Our first aim ivas to recognize the variability of species composition of central, eastern, and southeastern Slovenian semi-dry grasslands. The second aim was to define which environmental variables affect to the greatest extent the species richness and species composition of those meadows. The vegetation was sampled using standard procedure of the Braun-Blanquet approach. From each plot the following soil parameters were measured: pH, humus, carbonates, potassium, phosphorus; some environmental variables were also estimated by the El-ienberg indicator values. Phytosociologicat relevés were classified by TWINSPAN. Five clusters were separated and their configuration checked in a CA-ordination. For the interpretation of floristical gradient, the environmental variables were correlated with the ordination axes using rank correlation test. It could be summarised that species richness is slightly positively affected by humus and nitrogen amounts. We could also conclude that soil parameters as pHI humus, carbonates, humidity and nitrogen contents are those environmental variables that mostly affect species composition of the Central Slovenian Mesobromion meadows. Key words: Mesobromion erecti, semi-dry meadows, species richness, classification, ordination, phytosocioiogy, Hilenberg indicator values RELAZIONE TRA VARIABSLI AMBIENTALI, RICCHEZZA E COMPOSIZiONE Dl SPECIE IN PRATERIE SEMIARIDE SLOVENE DELL'ALLEANZA MESOBROMION ERECTI SINTESI Le praterie senna ride dell'alleanza centro-eurupea Mesobromion erecli (classe Festuco-Brornetea) vengono considerate come habitat ad alta biodiversity. Scopo principale di tale studio è stato quello cli riconoscere la variabilité dell a composizione di specie del le prat eric semiaride in Slovenia centrale, orientale e sud-orientale. Lo scopo sec-ondario invece era quello di definire quali variabili ambienrali influenzano prevalentemente la ricchezza e la composizione di specie di tali praterie. !! campionamento délia vegetazione è staio effettuato usando ia procedura standard dell'approccio di Braun-Bianquet, In ciascuna delle aree sono stati rilevati i seguenti parametri: pH, humus, carbcnati, potassio, fosforo; altre variabili ambre nt.ali sono state stimate attraverso l'indicatore di valori f.llenberg. I rilievi fitosociologici sono stati dassificati con il TWINSPAN. Dalla classiftcazione sono emersi S cluster e la loro configurazione è stata verificata con l'crdinamento CA. Per l'interpretazione dei gradient! floristici le variabili ambientali sono state correlate con gli assi dell'ordinamento usancio la conelazione di rango. Dai risultati ottenuti la ricchezza di specie risuita leggermente influenzata positivamente dall'humus e dalla quantita di azoto. La composizione di specie delle praterie di Mesobromion délia Slovenia centrale, invece„ si è rivelata influenzata in prevalenza da pH, humus, carbonati, umidità e contenuti di azoto. Parole chiave: Mesobromion erecti, praterie semiaride, ricchezza di specie, ciassificazione, ordinamento, fitoso- cioiogta, indicators di valori F.llenberg 141 ANNAIES • Ser. hist. nal. • 12 ■ 2002 • 2 Sonja ŠKORNIK & Milja KAUGARIČ: RELATION BDTWCiM ENVIRONMENTAL VARIABLES, SPiClES RlCHNtSS AND SPECIES COMPOSITION .... 141-152 INTRODUCTION The correlation between vegetation and environmental parameters is one of the most fundamental questions contributing to understanding plant species composition, structure in a particular habitat, landscape and region (Barbour et a/., 1987; Mucina, 1997). Although plant communities are dynamic entities undergoing continuous change in response to climate, land use patterns and intrinsic dynamics, understanding vegetation-environmental correlations at one point in time may heip to predict possible shifts attributed to climate and land use changes (Burke, 200)!. Dry and semi-dry grasslands are one of the best-known vegetation types in Europe (Dierschke, 1997). Mostly they are of semi-natural origin (Ellenberg, 1996), i.e. they developed by forest grazing and clear-cutting (Pott, 1996) oi after the abandonment of arable fields and vineyards (Schumacher ef a!., 1995) and are maintained by various activities - mowing, grazing of domestic animals, cutting or burning of shrubs and trees (Kienzle, 1979; Pfadenhauer & Erz, 1980; Wilschel, 1980). In Slovenia, all secondary dry and semi-dry grasslands on basic, neutral and slightly acid soil on calcareous bedrock flimestone, dolomite, marl, flysch - a calcareous sandstone) under the tree line belong to the class Festuco-Brpmetca Br.-BI. & R.Tx. ex Klika & Hadač 1944 em. Royer 1987 (Kal igar ič, 1997a; Skornik, 2000!. They are usually found in warm, sun-exposed areas. Those, iri winter cold and in the summer extremely hot sites with shallow soil layer, often dry out completely through the action of wind and direct solar irradiation (Kierchner et a!., 1980; Vogel, 1981). With about 700 vascular plants and 200 bryophytes and lichens, Festuco-Brpmetea grasslands are among the most species-rich habitats in Europe (Willems, 1990). In the last decades they have rapidly declined in their size and number in Central and Western Europe (Wolkinger & Piank, 1981) due to the changes in traditional land-use and extensive management (Horvat et a/v 1974; Willmans, 197S; Glavač ei at., 1979; Kinzel, 1983). The consequence is fragmentation and isolation of the remnant grasslands (Keymer & Leach, 1990). Other threat to this type of grasslands in Slovenia is their abandonment, where consequently secondary succession has changed many grasslands into scrub and forest (Kahgaric, 1997a, 1997b, 1998). In Slovenia, vegetation of Festuco-Brometea class is quite clearly divided into two orders: the sub-Mediterranean-lilyrian order Scorzoneretalia villosae Horvatič 197S, which is distributed in the south-western (sub-Mediterranean) part of Slovenia (Kaligarič, 1997a), and the Brometalia erecti Koch 1926 order that presents continental dry and semi-dry grasslands, characterised by sub-Atiantic-sub-Mediterranean species (Mucina & Kolbek, 1993). Brometalia erecti order includes semi-dry and dry grasslands of western, central and southern Europe. This order is represented by four alliances (Dier-schke, 1997). Sn Slovenia and in southern Europe, only alliance Mesobromion erecti (Br.-BI. & Moor 1938) Oberdorfer 1957 can be found (Skornik, 2000). The Mesobromion erect; grasslands have slightly mesophi-lous character - they mostly appear on sites with deeper, moderate humid soil, with pH values around 7. Therefore they are often assigned as "semi-dry" or "semiarid" grasslands ("Halbtrockenrascn"). As to floristic composition and synecology, this species-rich vegetation has an intermediate position between the extremely dry grasslands of the Brometalia erecti order, the acid grassland vegetation on nutrient-poor soils of the Cal-luno-Ulicetea class, and the mesophtlous grassland vegetation of the Arrhenatheretalia order (Mucina & Kolbek, 1993). Until now, only few qualitative descriptive studies of the Brometalia erecti vegetation in continental parts of Slovenia have been published (Tomazic, 1941, 1959; PetkovSek, 1970, 1974, 1977, 1978). The main objective of those studies was to describe the associations according to the Braun-Blanquet approach (Braun-Blanquet, 1964). One of the major aims of the present work was to understand the variation in species composition and species richness of the central, eastern and south-eastern Slovenian semi-dry grasslands (Mesobromion erecti alliance) in ecological terms using field data and numerical methods. MATERIAL AND METHODS In the year 1999, 35 plots (size of 25 m2} of semi-dry grasslands from the alliance Mesobromion erecti were selected in central, eastern arid south-eastern Slovenia (Fig. 1). Vegetation on the plots was sampled using standard procedure of the Braun-Blanquet approach (Braun-Blanquet, 1964; Westhoff & van der Maarel, 1973; Dierschke, 1994). Taxonomic nomenclature follows Martincic etal. (1999) except for Bromus erectus. The following taxonomies I ly complicated groups are presented as aggregates (agg.): Bromtfs condensates, B„ erectus and B. transsylvanicus as Bromus erectus agg., Brachypodium pinnatum and B. rupestre as Brachypodium pinnatum agg.; Leucanthemum ircutianum and L vulgare as Jleucanthemum vulgare agg.; C. mollugo, G. lucidum and G. album as Galium mollugo agg. All the grasslands are used as meadows, mown twice or at least once a year. Management exclude fertilisation, grazing or other treatments. From each plot the following soil parameters were analysed: 1. pH (measured in 0,1 N solution of KCl by glass electrode), 2. humus (Walkey-Black method), 3. carbonates (CaCOj) (volumetric by Scheibler calcic- 142 ANNALES • Ser. hist, nat, ■ f 2 • 2002 • 2 Sonja 5KOKNÏK & Milja KAUGARtC: «RATION B£TW£Eh! FNVIRONMtN tAL VARiA8l.ES. SFECItS RICHNESS AND SPECIES COMPOSITION Z. 14MS2 Fig. 1: Sampling plots distributed across central, eastern and south-eastern Slovenia. Legend: <$■ - 1* cluster, O -2nd cluster, • - 3rd cluster, □ - 4,h cluster, ■ - 5th cluster. SI. 1: Vzorčišča v osrednji, vzhodni in jugovzhodni Sloveniji. Legenda: <§> - 7. skupina, O - 2. skupina, ® - 3. skupina, □ - 4. skupina, M - 5. skupina. metre), potassium (K20) (flame photometry), and phosphorus (P) (spectrophotometry measurements at* the coloured complex). Some environmental variables were estimated by weighted (species frequencies are weights) averages of Ellenberg indicator values (Ellenberg et al., 1991) for iigbt, humidity, temperature and nitrogen content. Species richness per 25 nv was defined for each plot. For the numerical classification Twc-Way-INdicator-SPecies-ANaiysis (TWINSPAN; Hill, 1979) was applied. It was run using the computer program VEGI (Reiter, 1998). Correspondence Analysis (CA) was used to ordinate relevés (plots) using the computer package STAT1S-TiCA (Hirschfeld, 1935; Hill, 1973). For the interpretation of gradients extracted from CA ordination the environmental variables and richness values were correlated with the ordination axes. All correlations were tested by Spearman's rank correlation test, which was carried out using non-parametric statistics in STATISTICA. RESULTS AND DISCUSSION Classification and ordination of the relevés Phytosociological relevés of 35 plots are shown in Table 1. Sequence of the relevés is according to the TWINSPAN classification (Fig. 2). By classification procedure, five clusters with a size from 5-8 relevés (plots) were separated. For each cluster blocks of species, confirming slightly diverse species composition of the releves, are shown in the table. Clusters do not represent phytogeogiaphycallv based units, nor management-dependent units. They entirely depend on ecological conditions, varying due to the soil characteristics. Cluster 1 includes 7 plots. Differentia! species of the cluster are Agrostis capillaris, Festuca filiformis, Polygala vul- «4»»««« ooooo ©®o»a®afl □□□□□□OD asoosBB : 25 11 i« !r £ Jd M JO J6 >1 " > « N c 3® M I I u !> U w « : < ; i i i 1 1 O CA Axis 1 Fig. 3: C A (Correspondance Analysis) of Slovenian semi-dry grasslands (Mesobromion erecti alliance). 1-5 clusters defined by TWINSPAN are indicated. SI. 3: CA (Correspondence Analysis) ordinacija slovenskih polsuhih travišč (zveza Mesobromion erecti). Prikazane so skupine 1-5, določene s TWINSPAN analizo. Before correlating floristicaliy based gradients obtained from CA ordination with environmental parameters, the correlations among environmental variables were tested using Spearman's rank order correlation test The Spearman rank order correlation coefficients (R) between single environmental variables were calculated. Some of the environmental variables were found to be significantly correlated (Table 3), i.e. CaC03, which is positively correlated with pH, P, and K and negatively with humidity; pH is correlated with P and N values, etc. Species richness correlates positively with humus and nitrogen, which could be explained with natural fertility of the sampled meadows (fertilisation on plots were excluded). Finally, CA sample scores (coordinates) were correlated against all environmental variables, using Spearman's rank order correlation test (Tab. 4), Many of the environmental variables were found to be significantly correlated with CA sample scores. The first axis of the Correspondence Analysis (CAD was found to be positively correlated with humus, CaCOj and KvO, and negatively with humidity, it could be interpreted as 3 gradient from plots on deep and humid, decalcified brown soils to the plots on dry, shallow, calcareous soils. The second axis (CA2) was found to be strongly 2.36 ANNALES • Ser. hist. nat. • 12 • 2002 • 2 Sonja 5KORNIK. & Milj«i KALlCARIČ: RELATION BETWEEN ENVIRONMENTAL VARIABLE, SPECIES RICHNESS AND SPEOFS COMPOSITION .... 141-152 Tab. 1 : Phytosociological relevés of 35 Slovenian semi-dry grasslands (Mesobromion erecti alliance) classified by TWINSf'AN. Species, characteristic for each cluster are indicated in the tabic. Tab. 7; Fitosociološki popisi 35 slovenskih polsuhih travišč (zveza Mesobromion erecti alliacé}, klasificiranj s TWINSPAN analizo. V tabeli so označene vrste, značilne za posamezno skupino. Relevé number Viola canina Polygala vulgaris Calluna vulgaris Veronica officinalis Agrostis capillaris Festuca Cilifoxiais Carex pallescens Rbi.nan.thus minor Prunella 1aciniata Luzula campestris Carlina vulgaris Ononis spinosa Anthoxanthuir. odoratum Filipéndula vulgaris Cruciata glabra Knautia arvensis Achillea millefolium Rumex acetosa Holcus lanatus Knautia drymeia Primula vulgaris Peucedanum cervaria Centaurium erythraea Lathyrus pratensis Veronica chamaedrys Ranunculus acris Trifolium campestre Festuca pratensis Poa angustifolia Trisetum Elavescens Agrimonia, eupatoria Prunella vulgax-is Convolvulus arvensis Cynosurus cristatus Rhinanthus alectorolophus Pastinaca sativa Galium mol l ugo agg. Vicia cracca Medicago falcata Picris hieracioides Veronica jacquinii Chrysopogon gryllus Aster amellus Clematis vitalba Medicago lupulina Colchicum autumnale Avenula pubescens Hypericum perforatum. 2222222 1653472- O 22333: 89051 4 11 5 3 6 6 6 2 12 7 3 2 10 20 14 8 9 4 7 10 3 4 2 3 3 3 2 ■ 3 2 5 3 3 2 j 2 2 Q 8 5 6 2 3 2 2 7 5 4 12 .+.. ++. +++++++-; . 2 .++1+] . + + , . + . 21+1++Í 211.2+1 .++++.4 + + i +. + +. + +. + 332 . . + . t . + + + 111 + 1 . + . + 2+1 + + +1 + . . + +< + □ ■ 11131133210011110000000 7 984562302890134-4213576 ++ . + 11 1 + + 2 + + 1 + + . .111. + ++. . ++-Í-. . ■ ++ • +!• + . + . "K + + + 2 . . + + . + , 1+2+1+ + + . . + + + 1+ + 1+ + + +. +++! + + + . -H + + . + + 1-M + . + , -f T- H +*++. +1. . . + +12 +. +. . + +. . + . . ++. + . . . .33. + 1. . + + . ++ 2.36 ANNALES • Ser. hist. nat. • 12 • 2002 • 2 Sonja SKORNÍK& Milja KAUGAKlC: KtlAUON BETWEEN ENVIRONMENTAl VARIAÍUFS. 5PECIÍS RICHNESS AND SPECIES COMPOSITION .... Hl-132 Arrhenatherum elatius 10 8 • + +111 Daneus carota +...... + . 1. . . . ...... Centaurea jacea 23 +1+ .11 + . +++ .+1+12+ .+.+1.1. . . . + . + Sedum sexangulare 9 .....+4 . + . 4 + . + . , +. .+.+.... ...... Ranunculus bulbosus 13 +.+...+ . + + + +.....+ . . . 4 . .44 ...... Dactylis glomerata 26 + + + + + 4 . +12 + + J.++ + + + + + + + + + . . +..... Salvia px'atensis 3 0 2232 1222122 22222.+2 ..1+++ Brachypodium pinnatum agg. 31 21+1332 321. +33+222 2221.114 1.2111 Festuca rup.icola 29 2.+1.+4 2223 1222.+1 .+1+2.+4 .f. 4 .f. Leucantheraum vulgare agg. 24 3 ++++++H + 4+1 + . . . . + + . +4 . +4 4 . 4 >2> tí CÍ J. J, Iii Li Ulli. Anacampt i. s pyramidal i s ürobanche gracilis 6 3 ..... ......+ ...... Tragopogon orientalis + +1 + + . . . . + . Potenti1 la recta Tí1 -a 7*1 ^T/HT C? 8 3 ....... . . . + . . .41. . . . . + . . . i X ¿ly Ci X _L ca. V-LXJ.CIJ.ir Euphrasia stricta Dianthus car thusianorum Bromus erectus agg. 3 3 ....... + . . . ......+ J....... 31 +.322.1 3445 3114114 +13343.. 111112 Polygala comosa 17 +.....+ + . 1 + +4..+++ + + . . + . 4 4 Gentiana verna 6 ....... 4 . . . . +..... .... 4- . Gentianella germanica 2 ....... ....... ......+ . ...... Gentianopsis ciliata 2 ....... + . . . ....... ......+. ...... Geranium sanguineum 4 ....... .... . . 4-4 . . . +...+... ...... Teueri um cbamaedrys 21 +..++++ + . . + 2+2++.. 2++1+++-I Hi.erac.ium bauhinii 12 ++.++++ .....++-I . . + . . + Genista j&nuensis Thymus longicaulis 2 .. .1. . . 33 ++++ +.+ +211 +1++1++ ++11+2+4 +++++2 Helianthemum ovatum 23 . + . + . . + 1 + + 2 1.1+1+. + + + + + -H- . +..+++ Sanguisorba minor Viola hirta 29 + +..... +1+1 +1+1+12 +■. 1+++11 12 . + + +. + .. .. + ... . ++.,. +. . . +++- Buphthalmurn salicifolium 29 1++ 1-212112 + +21+2+. . ++11++ Euphorbia verrucosa 25 +1+.++ 1+1 +1...1++ +++ . . . .1,2 .1+++. Koeleria pyramidata 33 .221++ + 1+. 21+3+223 3 2 ^ X. ^ 2 2 2+++++ Carex flacca 27 4+____ 4+ . .22212+1 .+++.1+1 2++2++ Carex caryophyllea 17 1 . + . .1 . 4+ . + +.....+4 + "+■ . . . + « H . . + . + + Briza media 33 +++++1 2+11 ++++.++1 + 11++111I++1+2+. Plantago media 27 1+____ + 4 + + . 1212 + 11 .1.1++1+ +++++. Betónica officinalis 18 . 1 . + + . ++++. . . + +2.+1..4 Linuin catharticum 25 4 .+ .+ + . . + + 4..4+.++ + + + , +++ .!++ . + + + + Trifolium montanuin 29 .+ + + +1 + + + .1 +1+1.1.. ++++11+4 +.++++ Trifolium pratense Dorycnium germanicum 15 + + + + + + . . . + + . . +. +. 15 . 4 ... 4 . . , 4 ..+..+21 . ++ .... -1 + + 1. . . Danthonia decumbens 9 . 1 ... + + , . . . .+...+.. .1....+. .++... Lotus corniculatus 29 2++++- + +1 + + +++++1.4 1 + . + + . . . ■ + 4- + +1 + Plantago lanceolata 29 +1++++ 11 + 4 «j. ^ ^ 4* 'í* . +4.++..4 +++++, Galium verum 27 +2.121 122-i +11+..+1 ++1.11.4 2++.+. Pimpinella saxi fraga 28 +++++1 + 4 + 4 +++1.+ +t 4.1.+++. Genista sagittalis 23 .12221. + + + . . 421..... 3+1 + 1.1+ . +++.2+ Centaurea pannonica 13 ...++1 . . . + . .1+..... + + +..... +1..+. Succisa pratensis Peucedanum oreoselinuin 2 23 133222 + . . . . 1.11+1++. 12.23. . . 23.3. . Orchis tridentata Leontodon hispidus subsp, danubialis S 18 11+.++ + . ++ . ......+. .+ + + +. . 4 +..++. Hypochoeris maculata 9 .+.+++ ..... . ....... . - . 1 . . + . 4-..... Molinia caerulea 3 Pedicularis acaulis Potentilla alba Orchis morio 5 7 Danthonia alpina 26 3 . + 3 + + . . .2 +++.11.. 21.11+32 +331++ 2.36 ANNALES • Ser. hist. nat. • 12 • 2002 • 2 Sonja SKÖRNIK Wit ja KALSOARIC: RELATION* BETWEEN ENVIRONMENTAL VARIABLES, SPECIES RICHNESS AND SPECIES COMPOSITION .... III-IS? Potentilla erecta Inula hirta Scabiosa columbaria Carlina acaulis Hippocrepis comosa Globularia punctata Anthyllis vulneraria subsp. vulneraria Asperula cynanchica Centaurea scabiosa subsp. fritschii Euphorbia cyparissias Stachys recta Scabiosa triandra Prunella grandiflora Thlaspi praecox Campanula glomerata Silene nutans Carex montana Genista germanica Cirsiuro pannonicum Senecio jacobaea Rhinanthus glacialis Gyronadenia conopsea Anthericura ramosum Allium carinatum Cirsium acaule Ranunculus nemorosus Orchis ustulata Teucrium montanum Aquilegia vulgaris Hieracium pilosella Erica carnea Thalictrum minus Silene vulgaris Echium vulgare Gentiana utriculosa Chamaecytisus supinus Lilium bulbiferum Li num. viscosum Thalictrum simplex subsp. galioides Gentiana verna subsp. tergestina Leontodon incanus Polygala chamaehujcus Dianthus monspessulanus Antennaria dioica Knautia illyrica Plantago holosteum Tragopogon tommasinii Globularia cordifolia Thesium bavarum Carex humilis Potentilla tommasiniana Galium boreale Plantago argeatea subsp. Xiburnica Polygonatum odoratum Pseudolysimachion barrelieri subsp. barrelieri 16 8 7 20 26 26 24 23 20 IS 15 20 15 5 7 9 13 3 18 4 15 14 11 .A .12 9 9 9 10 4 11 3 3 3 2 2 2 Hi 1+11 + +!. - . . . + + + + + 1 + ■I- . . +. + + + + . + + . . . -i +++11+H +++121 ++. Ill 111+ 42++ J++1 11 11 +1 1 + 1 + 1 ,1+ •1+ -1+ . . . .1.+ + 1. + . . +++. . . . -M". + + + 1.++11 +12+2+ 1++1+1 11+1+1 ++11+. .++++. +++1++ 1.++. . +. . + . . +. . . . . +++. ++1.3+ +..... +. . . + -I-+++ + 1+.++3 +++1+2 +.+.+1 11+1 + + ..+-++1 +++.1+ + + + + . . . . +1. + + + +. . HI 1+1+12+2 . . . + . . . .31.+! +3 .21 . . + . . + . + 1...+32 +2+21. . . . + . -i + + ++ . . 1. . . + . + 12 . -1++.1 + + + + + 3322 . +.++.+ .+1+.1 +. + +-! + 2. . + + + -H- + +-. + t + . + . + + . . . + . + , . + 1 h+ . + . + . + . ++++.4 . .2++ 1+++.23 ++..+. .....4 ++++++. 2.1++1. . + . . . +1+++.. 32223.1 + .1. 1. + . +++1+++ 2.36 ANNALES • Ser. hist. nat. • 12 • 2002 • 2 Sonja SKORNIK & Mitja KAUCARJC: RELAIION BETWEEN ENVWONMÉNTM VARIABLES. SPECIES RICHNESS AND SPECIES COMPOSITION .... 141-552 Tab. 2: Values of measured and estimated environmental variables for 35 relevés of Slovenian semi-dry grasslands (Mesohromion erect* alliance). Legend: F. = variables estimated by weighted averages ofEllenberg indicator values. Tab. 2: Vrednosti izmerjenih in ocenjenih ekoloških parametrov za 35 popisov slovenskih polsuhih travišč (zveza /Vlesohromion erect/A Legenda: £ = parametri, ocenjeni s tehtanimi srednjimi vrednostmi Ellenbergovih indeksov. Measured variable EHenberg values Species richness/ 25 m2 CaCOj pH p2o; K jO Humus Humidity5 Ughtc Température^ NitrogenE relevés (%) (in KCl) (mg/100 g) (mg/100g) (%) 1 7.20 7.00 1.60 10.80 12.64 2.91 7,36 5.73 2.43 55 2 7.60 7.17 1.80 19.90 12.50 3.45 6.84 5.71 2,57 69 3 9.60 7.07 1.50 9.60 13.28 3.00 7.60 5.81 2.47 65 4 29.60 7.38 2.40 10.10 11.96 2.40 7.45 5.85 2.84 60 S 12.80 7.15 1.30 8.80 1 2.02 3.06 6.98 5.80 2,44 62 6 1.24 6.70 1.10 7.20 12.00 2.92 6.85 5.06 2.14 55 7 1.20 6.77 1.10 7.10 11.38 1.78 6.21 4.65 2.42 58 8 21.20 7.25 2.60 10.80 12.46 3.02 7.43 5.37 2.67 53 9 1.00 5.91 1.I0 6.20 9.90 3.49 7.96 4.93 2.57 50 10 5.60 6.67 1.90 7.70 11.10 3.24 7.50 5.36 2.59 54 11 1.20 6.85 1.40 8.70 8.80 3.23 7.11 5.74 2.34 50 12 21.60 7.01 0.80 8.00 7.42 3.34 7.19 5.54 2.81 56 13 3.20 6.74 1.40 8.90 6.98 3.31 6.11 5.96 2.15 45 14 29.20 7.18 2.20 7.90 12.12 3-42 7.54 6.12 2.42 42 15 52.00 7.22 ! .90 9.30 6.28 2.90 7.30 5.77 2.41 37 16 34.00 7.14 1.20 7.70 3.43 3.32 7.30 5.68 2.51 41 17 4.00 7.00 2.70 9.70 12.34 3.01 7.39 5.42 2.60 51 18 1.20 6.79 1.90 9.50 9.12 3.62 7.36 5.71 2.57 45 19 0.20 5.71 1.10 5.50 7.44 3.64 7.S7 5.67 2.78 54 20 0.40 6.30 1.30 6.10 10.26 3.44 7.53 5.71 2.20 50 21 0.04 4.68 1.60 1 3.80 3.02 3.38 7.73 6.00 2.32 43 22 0.16 5.S7 1.50 4.60 6.10 3.51 7.62 5.63 2.69 51 23 0.16 5.48 1.50 7.10 6.40 3.23 7.83 5.73 2.25 37 24 0.16 4.02 0.60 5.90 5,72 3.98 7.17 4.24 2.61 46 25 0.24 4.23 0.90 4.20 3.84 3.27 7.13 5.60 2.35 41 26 0.16 4.96 1.60 3.80 .3.77 3.38 6.91 5.98 2.31 50 27 0.20 5.60 0.80 3.00 3.53 3.56 6.99 5.60 2.42 46 28 0.08 6.31 'i .40 3.90 4.56 3.43 7.75 5.43 2.91 65 29 0.24 6.19 1.40 7.00 7.16 3.17 7.69 5.58 2.77 65 30 0.20 5.93 1.30 8.50 8.32 3.63 7.71 5.52 2.78 67 31 0.80 6.73 1.30 7.90 5.14 3.13 7.84 5.49 2.79 51 32 29.20 7.32 3.60 5.90 4.71 3.22 7.-71 5.62 2.66 45 33 21.20 7.10 4.00 20.40 6.08 3.55 7.26 5.83 2.38 37 34 24.00 7.39 2.90 18.30 5.64 3.54 7.71 5.66 2.68 48 35 3.20 7.17 3.20 5.70 6.16 3.04 8.14 5.61 2.75 51 negatively correlated with soil pH, nitrogen and species richness. Along this axis we could follow the gradient from naturally fertile basic (calcareous) substrates towards acid and leached, infertile soils. The third axis and the fourth axis (as well as the others) are not visible in the two-dimensional ordination, but they are also less important, because they usually describe less than 5% of the lota! variability. It is generalised for ah types of meadows that, fertilisation causes biodiversity loss. Furthermore, dry and semi-dry grasslands are also characterised by low supply of nutrients as the consequence of long lasting removal of aboveground biomass by mowing or grazing without additional fertilization (Gigon, 1968; Crime, 1990; Piis, 1994). But the low level of nutrients must be understood only relatively; due to the results of the present research 2.36 ANNALES • Ser. hist. nat. • 12 • 2002 • 2 Sonj» šKORNIk A M« j» KAUGARIČ RELATION BfTWUN INVIRONMFNTAl VARtAElFS, $P|CIES RiCHNiSS AND SPECIES COMPOSITION .... Ml-1 52 Tab. 3: Spearman rank order correlation coefficients (R) between environmental variables. Spearman R is given together with levels of probability # = p < 0.05, $- p <0.001. Tab. 3: Spearmanovi korelacijski koeficienti (R) med ekološkimi parametri, skupaj s stopnjami verjetnosti # - p < 0.05, $ ~ p < 0.001. Variable cacoj pH p2o5 Humu Humi1 Lipht' Temp* Nfc Sp.rich. CaCO, 1 pH 0.49# 1 p2o, 0.45# 0.5$ 1 k2o 0.55$ 0.31 0.49# 1 Humus 0.37# 0.11 0.15 0.45# 1 Humidity -0.41 # -0.22 -0.21 -0.22 -0.39# 1 light6 -0.17 0,42# 0.25 -0.05 -0.19 0.1 1 Temperature 0.15 -0.03 0.09 0.27 0.1 -0.24 -0.18 i NitrogenE 0.07 0.52$ 0.07 -0.05 0 0.11 0.33 -0,26 1 Species richness -0.05 0.17 -0.05 0.05 0.53$ -0.22 -0.08 -0.07 0.5# 1 Tab. 4: Spearman rank order correlation coefficients (Rj between environmental variables and CA 1-4. R is given together with levels of probability # = p < 0.05, $ = p <0.001. Tab. 4: Spermanovi korelacijski koeficienti (R) med ekološkimi parametri in CA 1-4. R je prikazan skupaj s stopnjami verjetnosti #-p < 0.05, $ = p< 0.001. Variable CA1 ca 2 ca3 ""cm j cac03 0.53# -0.4 -0.41 # -0.01 PH -0.06 -0.83$ -0.17 0.06 PA 0.08 -0.3 -0.28 -0.28 i<2o 0.47# -0.26 -0.1 b -0.11 Humus 0.77$ -0.22 0.18 -0.28 Humid ityf -0.45* 0.33 -0.1 7 -0.09 LightE -0.39 -0.35 -0.19 -0,07 Tempera tu re€ 0.27 0.03 -0.01 -0.18 Nitrogene -0.23 -0.44# 0.17 -0.1 7 Specie.s richness 0.27 -0.41 # 0.60$ -0.33 it could be summarised that species richness is positively affected by humus and nitrogen amounts. Deeper and naturally fertile soils enable a very wide spectrum of species, starting from the contingent of Brometalia to- wards to the rich contingent of Arrhenatheretalia order as well. It could be interpreted that species richness on naturally fertile soils is high due to the neutrophilous and mesoph'rlous species occurring in these conditions. It is known that unfertilised semi-dry and dry meadows are colonised by many rare and threatened species, which are adapted to high solar irradiation, heat, drought and cold winter period, to nutrient poor conditions (Ellenberg, 1996) - interpreted also as mineral nutrient stress (Grime, 1976, 19903 if these selected species are present, those meadows are automatically considered as "species-rich grasslands" due to the presence of "more important" species. Calcareous substrate is afso known (o increase species richness (Kinzel, 1983), but in our research the correlation between species richness, CaCO^ and pii were not statistically significant. One reason is probably the fact that all the plots have developed on soils on calcareous substrates (dolomite, limestone, marl, flysch). The other reason could be the fact that mainly all sampled plots presented typical Slovenian semi-dry grasslands which were in very good condition, due to the favourable ecological characteristics ot the localities and extensive management regime. 2.36 ANNALES • Ser. hist. nat. -12- 2002 • 2 Sofija ŠKOF NIK ft Mitja KAUCARIČ: RELATION BETWEEN ENViRONMtNTAL VARIABLES. SrEOES RICHNESS AND SPECIES COMPOSITION .... 141-152 POVEZAVA MED EKOLOŠKIMI PARAMETRI, ŠTEVILČNOSTJO RASTLINSKIH VRST IN FLORISTIČNO SESTAVO SLOVENSKIH POLSUHIH TRAVIŠČ ZVEZE MESOBROMION ERECT! Sonja ŠKORNIK & Mitja KAUGARiČ Oddelek za biologijo, Pedagoška fakulteti. Univerzi v Mariboru, SI-2000 Maribor, Koroška 160 in Institut za biodiverziteme študije, Znanstveno raziskovalno središče republike Slovenije, Koper, Si-6000 Koper, Garibaldijeva 18 F.-mail: 5onja.skornik@uni-mb.si POVZETEK Polsuha travišča zveze Mesobromion erecti (Br.-BI. & Moor 1938) Oberdorfer 1957 sodijo med habitate z visoko biodiverziteto. Flor ¡stično diverziteto lahko najpreprosteje označimo kot število vrst na določeni površini (v našem primeru je bila površina 25 nr). Namen naše raziskave je bil na osnovi 35 raziskovalnih ploskev (sestojev polsuhih travišč, izbranih na območju srednje, vzhodne in jugovzhodne Slovenije) ugotoviti povezavo med floristično sestavo teh travišč, številčnostjo rastlinskih vrst in izbranimi ekološkimi parametri. Vsa izbrana travišča vzdržujejo z ekstenzivno nego - redno košnjo enkrat na leto brez gnojenja. Vegetacijo smo vzorčili po standardni Braun-Blanquetovi metodi. Hkrati s popisi smo na vzorčnih površinah vzeli tudi vzorce tal, ki so jim bile določene naslednje lastnosti; pH, količina organskih snovi, karbonatov ter deleža kalija in fosforja. Razmere na rastiščih smo ocenjevali tudi na podlagi tehtanih srednjih vrednosti Ellenbergovih ekoloških indeksov za svetlobo, vlago, temperaturo in vsebnost, dušika. Klasifikacijo fitocenoloških popisov smo opravili z analizo TWINSPAN. Opravljena je bila tudi ordinacija popisov CA (Correspondence. Analysis). Na podlagi obeh analiz smo dobili pet dobro ločenih skupin (klastrov) s 5 do 7 popisi. Za interpretacijo florističnih gradientov, ki so se pokazali po ordinaciji CA, smo koordinate CA posameznih popisov s Spearmanovim korelacijskim koeficientom primerjali s pripadajočimi izmerjenimi in ocenjenimi ekološkimi parametri. Pri tem se je pokazalo, da so številni parametri v statistično značilni korelaciji s koordinatami CA. Ptva ordinacijska os je v pozitivni korelaciji z vrednostmi za humus, karbonate, vlažnost in kalij in jo lahko interpretiramo kot gradient od popisov na globokih in vlažnih rjavih tleh, do popisov na plitkih, suhih, karbonatnih tleh. Druga os je v negativni korelaciji z vrednostmi pH in vsebnostmi dušika v tleh; vzdolž te osi lahko spremljamo gradient od naravno hranilnih, bazičnih tal do spranih, kislih in s hranilnimi snovmi revnih, pustih tal. Iz dobljenih rezultatov povzemamo, da je številčnost rastlinskih vrst na traviščih, ki sicer niso umetno dognojevanj v rahli pozitivni odvisnosti z vsebnostmi humusa in dušika v tleh. Iz ordinacije CA, ki temelji na floristični sestavi izbranih eksperimentalnih ploskev, lahko jasno razberemo nekatere ekološke gradiente. Zaključujemo, da so pH, vsebnost humusa, karbonatov in dušika v tleh ter vlažnost, tal tisti ekološki dejavniki, ki najmočneje vplivajo na vrstno sestavo polsuhih travišč zveze Mesobromion erecti v osrednji, vzhodni in jugovzhodni Sloveniji. Ključne besede: Mesobromion erecti, polsuha travišča, številčnost rastlinskih vrst, klasifikacija, ordinacija, fitosociologija, EHenbergovi ekološki indeksi REFERENCES Barbour, M. C., J. H. Burk & W. D. Pitts (1987): Terrestrial plant ecology. Benjamin Cummings Publishing Company, Merilo Park, CA. Braun-Blanquet, J. (1964): Pflanzensoziologie. Grundzüge der Vegetalionskunde. Springer Verlag, Wien, New York. Burke, A. 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