©Slovenian Entomological Society, download unter www.biologiezentrum.at LJUBLJANA, JUNE 2004 Vol. 12, No. 1: 57-72 XVII. sieec, Radenci, 2001 CENOSES AND SPECIES PHENOLOGY OF CARABID BEETLES (COLEOPTERA: C ARAB ID AE) IN THREE STAGES OF VEGETATIONAL SUCCESSION IN UPPER PIVKA KARST (SW SLOVENIA) Slavko POLAK Notranjski muzej Postojna, Ljubljanska 10, SI-6230 Postojna, Slovenia, e-mail: slavko.polak@guest.arnes.si Abstract - The Carabid beetle cenoses in three stages of vegetational succession in selected karst area were studied. Year-round phenology of all species present is presented. Species richness of the habitats, total number of individuals trapped and the nature conservation aspects of the vegetational succession of the karst grasslands are discussed. Key words: Coleoptera, Carabidae, cenose, phenology, vegetational succession, karst Izvleček CENOZE IN FENOLOGIJA VRST KREŠIČEV (COLEOPTERA: CARABIDAE) V TREH STADIJIH ZARAŠČANJA KRASA NA ZGORNJI PIVKI (JZ SLOVENIJA) Raziskali smo cenoze hroščev krešičev v treh sukcesijskih stadijih zaraščanja izbranega kraškega območja. Za vsako od ugotovljenih vrst je podana njena celoletna fenologija. Obravnavani so pestrost vrst po habitatih, skupno število ujetih osebkov in naravovarstveni vidiki zaraščanja kraških travišč. Ključne besede: Coleoptera, Carabidae, cenoze, fenologija, zaraščanje, kras Introduction Until the late 19th century the Slovene Littoral Karst (Kras) and, in part, the southern slopes of the higher karst plateaus in southern Slovenia, resembled rocky semi-desert, covered sparsely by grass and scrub. This condition was brought about 57 ©Slovenian Entomological Society, download unter www.biologieiAStaifrtlflpniologica slovenica, 12 (1), 2004 by intense agricultural use, overgrazing by sheep and goats, burning and logging since ancient times. There are only small remnants left of the original forests. In the early 19th century the Austrian government began a series of successful reafforestation campaigns. As a consequence of nearly two centuries of reafforestation efforts, the Littoral Karst is now predominantly (55 %) forested, mainly by Austrian pine (.Pinus nigra) plantations and secondary forest. The Austrian pine woodlands are pioneers and when they reach maturity they naturally convert to the original broad-leaved forests as the pine dies out. At the same time the Austrian pine is now spreading over the abandoned calcareous grasslands and bare, stony ground that is now disappearing very rapidly. Flowery karst meadows are from nature conservation view highly valuable when assessed using different animal and plant groups such as birds (Trontelj 2000), butterflies (Habeler 1992, Čelik & Rebeušek 1996) and plants (Kaligarič 1997). Lack of human exploitation of very biodiverse karst grasslands and meadows is therefore bringing about the loss of this biodiversity. In recent years this has become one of important nature conservation issues in Slovenia. Only a few and local Carabid beetle cenose and species phenology investigations have been made in Slovenia so far (Drovenik 1978, Slapnik 1988, Furlan 1988, Vrezec 2000) and knowledge is still fragmented. In the present study I have investigated the species' richness and species' phenology of the Carabid beetles in the different stages of vegetational succession and I especially tried to answer the question of how the Carabid beetle cenoses react to the high rate of afforestation in the Slovene karst. Investigated Area and Methods I investigated the Carabid beetle fauna in three vegetational succession stages in the Upper Pivka karst in south-west Slovenia. The Pivka karst is an extensive valley on the western slopes of the high karst Snečnik plateau. The Snežnik plateau, at above 1000 meters in altitude, is well forested mainly with broadleaf and mixed forests of beech Fagus sylvatica and Abieti-Fagetum s.lato. The investigated area at approximately 600 m above sea level was once totally deforested pastures and grasslands. There remained only small remnants of Oak woodlands spared for litter collection. I investigated Carabids in the three succession stages of vegetational succession. The first area where I collected the Carabid beetles is dry, calcareous karst grassland and meadows that include bare, stony ground which is being rapidly swamped by various kinds of scrubland and mainly young Austrian pine trees in different phases of succession. The second vegetational succession stage that I investigated the Carabid beetles was a plantation of mature Austrian pine woodland. The trees are dense and there are few other tree species, but in a last ten years many other broad-leaved species such as wild cherry Prunus avium, oak Quercus sp. and flowering ash Fraxinus ornus have started to grow. I chose the mature oak forest as a final stage of the vegetational succession of the area. In the turkey oak woodland Quercus cerris and durmast oak Quercus petrea 58 S. Polak: Cenoses and species phenology of carabid beetles in three stages of vegetational succession on upper Pivka Karst predominate, but there are some other broadleaf tree species as well as some Austrian pine trees in the forest clearings. In each investigated habitat, I put 10 simple pit-fall traps in line approximately 15 meters apart. The 1/4 litre plastic containers were filled with salt solution for preservation. I added to the solution some drops of detergent to avoid static and some millilitres of old vinegar that is known as a ground beetle attractant. The traps were covered by tree bark to avoid flooding in the case of rain. I started with sampling in June 1995 and finished in June 1996. The traps were checked approximately every two weeks and in winter time every three weeks. The specimens that were counted, prepared and determined are preserved in the Collection of Notranjski muzej Postojna. The systematic is that followed by Drovenik & Peks (1999). The year-round phenology histograms for the most common species (eudominant and dominant) are made on the basis of the data collected. To evaluate the Carabid beetle cenoses of the three studied vegetational succession stages in the investigated area we calculated active dominance (DA) for all three investigated habitats using the formula (Tarman 1992): DA = No. individuals particular species x 100 / No. of all individuals of all the species Eudominant species > 10 % Dominant species 5 to 10 % Subdominant species 2 to 5 % Recedent species 1 to 2 % Subrecedent species < 1 % Results During the trapping over the one year period 1043 individuals were collected of 28 species of Carabid beetle. The smallest number (171) of the individuals was trapped in the dry karst grassland in the first stages of vegetational succession. In the Austrian pine woodland the number of trapped individuals was the highest (573) and lower again (299) in the last habitat of oak woodland. Among 28 collected species 20 species were trapped in the karst grassland, 21 in the Austrian pine woodland and 17 species in the oak woodland. The number of individuals of a particular ground beetle species and the percentages of species in each investigated habitat are shown in the Table 1. 59 ©Slovenian Entomological Society, download unter www.biologieiAStaifrtlflpniologica slovenica, 12 (1), 2004 Table 1: The number of individuals of a particular Carabid beetle species and the percentages of species in each investigated habitat in Upper Pivka karst (SW Slovenia). Karst grassland % Pinus nigra woodland % Quercus sp. woodland % Together Carabus catenulatus 13 7,6 6 1 50 16,7 69 Carabus hortensis 0 0 19 3,3 79 26,4 98 Carabus convexus 0 0 2 0,3 17 5,7 19 Carabus violaceus 50 29,2 3 0,5 2 0,7 55 Carabus coriaceus 33 19,3 7 1,2 5 1,7 45 Leistus rufomarginatus 0 0 26 4,5 3 1 29 Notiophilus biguttatus 0 0 1 0,2 0 0 1 Notiophilus palustris 0 0 2 0,3 0 0 2 Notiophilus rußpes 3 1,8 4 0,7 1 0,3 8 Notiophilus substriatus 1 0,6 0 0 0 0 1 Panageus bipustulatus 1 0,6 0 0 0 0 1 Myas chalybaeus 1 0,6 20 3,5 2 0,7 23 Poecilus koyi 1 0,6 0 0 0 0 1 Pterostrichus melanarius 1 0,6 1 0,2 0 0 2 Abax carinatus 0 0 1 0,2 0 0 1 Abax ovalis 8 4,7 229 40 65 21,7 302 Abax parallelepipedus 7 4,1 100 17,5 54 18,1 161 Molops ovipennis 29 17 37 6,5 10 3,3 76 Calathus fuscipes 4 2,3 4 0,7 1 0,3 9 Calathus cf. glabricollis 3 1,8 1 0,2 1 0,3 5 Synuchus nivalis 2 1,2 0 0 0 0 2 Laemostenus cavicola 0 0 1 0,2 1 0,3 2 Harpalus marginellus 0 0 1 0,2 1 0,3 2 Lebia clorocephala 1 0,6 0 0 0 0 1 Dromius notatus 8 4,7 1 0,2 1 0,3 10 Microlestes sp. 2 1,2 0 0 0 0 2 Aptinus bombarda 2 1,2 107 18,7 6 2 115 Brachinus explodens 1 0,6 0 0 0 0 1 No. of individuals 171 573 299 1043 No. of species 20 21 17 28 1. Carabid beetle cenoses Karst grassland Carabid beetle cenose Among the 20 species that were found in the dry calcareous karst grassland of the investigated area 3 species are eudominant (Fig.l). The most common is Carabus 60 S. Polak: Cenoses and species pheroiQgjfErfBWe^d^i^t^iaiy^lMSsieniitagesitef vegelatjejial:sm& s> & & & & £> ,?> „q> ctf p) or ,<3? ,cs ¿o .§15 o 8.10 i grassland -rinus nigra wuuuianu vjueiuus» sp. vvuuuidiiu j (S> , S> sv A 8> S> & S> £p & ,a Fig. 5: Carabus hortensis phenology and habitat preference in Upper Pivka karst (SW Slovenia). Carabus convexus (Fabricius 1775) Our data clearly show that this species prefers the thermophilic oak woodland. In the coldest Austrian pine forest we trapped only two specimens and none in the dry grassland. It seems that the species has three generations one in April and May, second in July and August and a third in October. 64 S. Polak: Cenoses and species phenology of carabid beetles in three stages of vegetational succession on upper Pivka Karst Carabus violaceus (Linnaeus 1758) Contrary to C. convexus this species clearly shows a preference for grassland habitats. It was the most common (eudominant) species in the karst grassland under investigation. The specimens trapped in the other two habitats seem to coincide with breeding dispersal. Despite of the fact that the first specimens had already emerged in May the most obvious peak (probably a second generation) starts at the end of July and finishes in the middle of September (Figure 6). Carabus violaceus -karst grassland Pinus niyia woodland Quelcus sp. woodland ; 15 T in c 10 4 / \ E / o W • o>' o> /V Ji? J? ^ >V fv "v "V K N. Fig. 7: Carabus coriaceus phenology and habitat preference in Upper Pivka karst (SW Slovenia). 65 ©Slovenian Entomological Society, download unter www.biologieiAStaifrtlflpniologica slovenica, 12 (1), 2004 Leistus rufomarginatus (Duftschmidt 1812) In the investigated area the pine woodland seems to be the most suitable habitat. Only three specimens were trapped in the oak woodland. The species is present in the cold part of the year from the October to January with an obvious peak in mid-November. The second less obvious generation emerges in May. Notiophilus biguttatus (Fabricius 1779) Only one specimen of this species was trapped in Austrian pine forest on 19th May. Notiophilus palustris (Duftschmidt 1812) One specimen of this species was trapped on 19th May and another on 15th October, both in the Austrian pine forest. Notiophilus rufipes (Curtis 1829) Among the Notiophilus species this was the commonest one. 3 specimens were trapped in the karst grassland, 4 in the Austrian pine forest and 1 in the oak forest. It is present in April, July and in September. Notiophilus substriatus (Waterhouse 1833) Only 1 specimen was trapped (4. 11. 1995) in dry grassland which shows the helio-philic character of this species. Panagaeus bipustulatus (Fabricius 1775) This southern European species prefers dry habitats, proved by our finding of a specimen on 1st July in the dry grassland. Myas chalybaeus (Palliardi 1825) The distribution of this Balkan species also reaches southern Slovenia. Our data clearly show that it prefers Austrian pine woodland, where it is subdominant among the other species. It starts to emerge in June but becomes commonest in July and August. The latest specimen was trapped at the end of September. Poecilus koyi (Germar 1824) This species is also a south European representative. It prefers open areas. The only specimen trapped was in the karst grassland on the 14th August. Pterostichus melanarius (Illiger 1798) This species was found only twice. One specimen was on 26th July in Austrian pine forest and the second on 10th September in the grassland. Abax caiinatus (Duftschmidt 1812) Contrary to the Abax ovalis this species is rare in the investigated area. The only specimen was found in the pine forest on 26th July. 66 S. Polak: Cenoses and species phenology of carabid beetles in three stages of vegetational succession on upper Pivka Karst Abax ovalis (Duftschmidt 1812) This central and southern Europe species has a montane and subalpine character. It prefers wet forest habitats. Therefore it is not a coincidence that it was most common in the Austrian pine forest and a bit less common but still eudominant in the oak woodland. The species occurs only accidentally in the grassland habitat. This species starts to emerge in the middle of May, it reaches its first maximum in second half of May. The next distinctive appearance of the species is in July and beginning of August and the third one, quite obvious in mid-November. The last specimen was trapped on 26th November (Figure 8). Abax ovalis karst grassland-Pinus nigra woodland-Quercus sp. woodland Fig. 8: Abax ovalis phenology and habitat preference in Upper Pivka karst (SW Slovenia). Abaxparallelepipedus (Piller & Mitterpacher 1783) In the investigated area this species shows similar figure to Abax ovalis. The species predominates in the Austrian pine forest, but is a bit less common in the oak woodland and appears only accidentally in the karst grasslands. The species appear for the first time at the beginning of May and finishes its season in mid-October. The species has at least two distinctive peaks one in May and second in July (Figure 9). 67 ©Slovenian Entomological Society, download unter www.biologieiAStaifrtlflpniologica slovenica, 12 (1), 2004 Abax parallelepipedus - - karst grassland Pinus nigra woodland ■ Quercus sp. woodland o ty rV" 5' >* V <0" • <0' S>' S*' ^ v r^-' & ' ^ jy Jz Fig. 9: Abax parallelepipedus phenology and habitat preference in Upper Pivka karst (SW Slovenia). Molops ovipennis (Chaudoir 1847) This species lives in the montane and subalpine habitats in the southern and southeastern Alps. It seems common on the submediterranean edge of the montane Snežnik plateau as well. Despite the literature which characterizes this beetle as a forest species my data and the results of Drovenik (1978) in Trnovski Gozd, show that it occurs in open grassland habitats too. According to the data collected in this study the species is the most common in Austrian pine forest where is classified as a dominant species. It is quite common in the calcareous karst grassland but much rarer in the oak forest. Molops ovipennis has two distinctive peaks in its appearance; despite this some specimens were caught in other periods also. The spring generation appears at the end of March, reaches its peak at the end of April and lasts to the end of May. We found only one specimen in July and one again in August. The second distinctive generation starts in September reaching a peak in November and December and finishes its appearance at the beginning of February. It is interesting that during the spring emergence the species was the most abundant in grassland habitats whilst in the autumn it was found most frequently in the Austrian pine woodland (Figure 10). 68 S. Polak: Cenoses and species phenology of carabid beetles in three stages of vegetational succession on upper Pivka Karst Mo!ops ovipennis karst grassland-Pinus nigra woodland-Quercus sp. woodland -5& S? S? S? £ S? & & -