UDK 630*111 + 164 (001) Izvorni znanstveni članci – Original scientific papers doi:10.31298/sl.143.1-2.4 Šumarski list, 1–2 (2019): 35–43 FLORISTIC AND MICROCLIMATIC FEATURES OF THE SOVLJAK DOLINE (MT. VELIKA KAPELA, CROATIA) FLORISTIČKE I MIKROKLIMATSKE ZNAČAJKE PONIKVE SOVLJAK (VELIKA KAPELA, HRVATSKA) Tihana VILOVIĆ1, Suzana BUZJAK2, Nenad BUZJAK3 SUMMARY The relation between floristic composition, microclimate and geomorphology of a large-sized karst doline was analysed in the area of the Sovljak doline located on the Mt. Velika Kapela. Habitat conditions in various parts of the doline, due to its morphology, were described in this work. Geomorphological observations, microclimatic measurements (including air temperature, relative humidity and dew point temperature data) and flora inventory were carried out. Ellenberg’s indicator values, life forms, chorological and taxonomical analyses were performed, as well as the analysis of habitat similarity. The doline slopes (northern and southern) appeared to offer different habitat conditions than its bottom, due to their morphological and microclimatic differences, which resulted in high taxa variability along short distances in the doline. Furthermore, the presence of temperature inversion pro- moted the development of the vegetation inversion, which is common in such large dolines. KEY WORDS: microclimate, geomorphology, flora, Ellenberg’s indicator values, vegetation inversion INTRODUCTION clearly expressed in dolines with greater depth, and in those UVOD situated on higher elevations (Šegota and Filipčić, 1996). Furthermore, microclimatic conditions influence the com- Dolines are natural enclosed depressions found in karst position and distribution of vegetation, thus, air tempera- landscapes, considered as diagnostic landform of such land- ture inversion can also lead to the vegetation inversion in a scapes. Besides their geomorphological context in karst, doline (Horvat, 1962). dolines are also described as interesting localities due to As a result of different type of genesis and evolution, dolines their special microclimatic, ecological and vegetational fea- differ in their morphological features, which are the main tures. The climate of the dolines differs from the climate of criteria for their classification, together with their morpho- the surrounding area, mainly because of the different genesis (Bondesan et al., 1992). Their horizontal dimensions amount of the radiation they receive, which depends on the may range from only a few meters, to a few hundred meters. exposition and inclination of the doline slopes (Cernatič- With the sides ranging from gently sloping to vertical, their Gregorič and Zega, 2010). As a concave relief form, they depth can vary from a few, to tens of meters. Morphoge- favour the formation of air temperature inversion, more netically, dolines can be classified into four main categories, 1 Tihana Vilović, MSc, University of Zagreb, Faculty of science, Department of Botany, Marulićev trg 20/II, HR-10 000 Zagreb, Croatia, [email protected] 2 Suzana Buzjak, PhD, Croatian Natural History Museum, Demetrova 1, HR-10 000 Zagreb, Croatia, [email protected] 3 Nenad Buzjak, PhD, University of Zagreb, Faculty of science, Department of Geography, Marulićev trg 19/II, HR-10 000 Zagreb, Croatia, [email protected] 36 Šumarski list, 1–2, CXLIII (2019), 35–43 concerning the type of the development process, which in- mensions. It is situated on the eastern slope of the Mt. Ve- clude dissolution (corrosion), collapse, suffusion or subsid- lika Kapela, 8.5 km SSW from the town of Ogulin, between ence (Williams, 2004). However, their genesis often includes the regions of Ogulinsko-plaščanska udolina valley on the more than just one process, thus the majority of the dolines east and the Gorski kotar on the west (Fig. 1). have polygenetic origin, even though one process is always The researched karst area is mostly covered by thermophilic dominant (Ford and Williams, 2007). beech forest (ass. Ostryo-Fagetum M. Wraber ex Trinajstić This study aimed to identify the habitat conditions in dif- 1972). Considering the Köppen-Geiger climate classifica- ferent parts of the Sovljak doline, situated on the Mt. Velika tion, this area belongs to the moderately warm climate type Kapela. Also, the aim was to investigate its microclimate, in with warm summer (Cfb), with mean July temperature be- order to detect a potential temperature inversion, which tween 20 and 22 °C and mean January temperature between may, if intense and frequent enough, cause the occurrence 0 and -3 °C. The precipitation is equally distributed during of vegetation inversion. Similar investigations were made the year, with the lack of a dry period (Kottek et al., 2006; by Lausi (1964) and Favretto and Poldini (1985) in Italy, Šegota and Filipčić, 1996). Bátori et al. (2009, 2011, 2012, 2016) and Bárány-Kevei (2011) in Hungary, Özkan et al. (2010) in Turkey, Antonić Basic geological conditions of the doline’s et al. (1997), Vrbek et al. (2010), Buzjak et al. (2011) and geomorphological evolution – Osnovni geološki uvjeti Surina (2014) in Croatia. geomorfološkog oblikovanja ponikve The Upper Jurassic carbonate rocks (Malm series) dominate RESEARCH AREA the research area, with two members which can be distin- PODRUČJE ISTRAŽIVANJA guished. Their characteristics determined by geological con- The Sovljak doline was chosen as an interesting site, since ditions and geomorphological processes are contributing to 2 it stands out by its funnel shaped morphology and large di- internal biotope conditions. The J3 member is represented Figure 1. Geographic position of the Sovljak doline with the locations of data loggers: TH9 – southern exposition slope, TH10 – bottom of the do- line, THMI-2 – northern exposition slope (URL 1) Slika 1. Geografski položaj ponikve Sovljak s lokacijama termohigrografa na mjernim točkama: TH9 – padina južne ekspozicije, TH10 – dno ponikve, THMI-2 – padina sjeverne ekspozicije (URL1) VILOVIĆ T. i dr.: FLORISTIC AND MICROCLIMATIC FEATURES OF THE SOVLJAK DOLINE (MT. VELIKA KAPELA, CROATIA) 37 by algal limestones, dolomites and dolomites with the lime- sitions, and at the bottom of the doline. The taxa were stone lens. Its main lithological characteristic is alteration of mostly identified in the field, with some exceptions, which 3 dolomites and limestones. The younger member J3 is rep- were collected and identified subsequently using standard resented by algal-foraminiferal limestones and dolomites floristic literature (Tutin et al., 1968 – 1980, 1993; Pignatti from the Lower Malm. Various types of limestones with mud 1982; Jávorka and Csapody, 1991; Domac, 1994). The plant or sparicalcitic cement and crystalinic dolomites are a char- material is partly deposited in the Herbarium Collection of acteristic feature of this member (Velić and Sokač, 1981). the Croatian Natural History Museum (CNHM). The no- The Quartar sediments are mostly eroded, but they appear menclature follows Flora Croatica Database (Nikolić, 2018). locally in the doline as the rock-creeped breccias. In the tec- We have performed taxonomic, chorological, Ellenberg’s tonic structure of the researched area, intense tectonic frac- indicator values (hereafter: Eiv) and life form analyses. Be- tures can be distinguished. The facilitating factor for the gen- sides the analysis of the total flora, the floristic analysis for esis of the doline was its position on the interception of faults, different parts of the doline was also performed, using the with the spreading directions NW – S, SE and NE – SW, and Sörensen index of similarity. Legal protection of taxa was also the presence of a few secondary fractures. Due to the determined according to the Nature Protection Act (Offi- limestone/dolomite alternation and by tectonic stress dense cial Gazette 80/2013) and the Ordinance on Strictly Pro- network of fissures the doline is characterized by intense tected Species (Official Gazette 144/2013, 73/2016). More- rock disintegration and slope processes, especially in the part over, the taxa listed in the Red Book of Vascular Flora of built of dolomite. Along the fault lines there are steeper Croatia (Nikolić and Topić, 2005) were marked using the slopes with rock debris at the base. Different slope inclina- adequate IUCN designations: VU – Vulnerable, NT – Near tion and geomorphological processes therefore resulted in Threatened, LC – Least Concern, DD – Data Deficient. pedogenesis (alternation of bare rocks, shallow brown soils Chorological analysis follows the classification used by on limestones and dolomites, thicker colluvium deposits be- Horvatić et al. (1967 – 1968). The chorological groups used low steep slopes), local hydrological paths of water infiltra- in this paper are: 1 – Mediterranean, 2 – Illyrian-Balkan, 3 – tion and microclimate (exposition and humidity). South-European, 4 – Atlantic, 5 – East European-Pontic, 6 – Southern-East European, 7 – Central European, 8 – Euro- MATERIAL AND METHODS pean, 9 – Eurasian, 10 – Circumholarctic, 11 – Widespread. MATERIJAL I METODE The data were taken from the Flora Croatica Database (Nikolić, 2018) and from the following literature sources: Tu- To gain wider perspective of the investigated area, a few dif- tin et al. (1993), Pignatti (1982), Buzjak (2001), Pandža ferent types of research were included in this study, such as (2010), Nežmah and Ljubičić (2012), Britvec et al. (2014). geomorphological, microclimatic and floristic research. Life forms and ecological indicator