Spatial and temporal dynamics of invertebrates ... - Springer Link

Biologia 67/6: 1143—1151, 2012 Section Zoology DOI: 10.2478/s11756-012-0113-y

Spatial and temporal dynamics of invertebrates dwelling karstic mesovoid shallow substratum of Sivec National Nature Reserve (Slovakia), with emphasis on Coleoptera Michal Rendoš1, Andrej Mock1* & Tomáš Jászay2 1

Pavol Jozef Šafárik University, Faculty of Sciences, Institute of Biology and Ecology, Moyzesova 11, SK-04167 Košice, Slovakia; e-mail: [email protected], [email protected] 2 The Šariš Museum in Bardejov, Radničné námestie 13, SK-08501 Bardejov, Slovakia; e-mail: [email protected]

Abstract: Interior spaces of the forested rocky debris (MSS) represent a transition zone between the surface and deep underground spaces and a place of animal adaptation to underground life. They serve as a refuge for relict fauna as well. The study was conducted in the limestone scree slopes in Sivec National Nature Reserve (Čierna Hora Mts, Western Carpathians, elevation about 500 m a. s. l.) covered by linden-maple forest from September 2008 to November 2009. The effort was to define the vertical and seasonal aspects of invertebrates and temperature regime. Invertebrates were collected by using subterranean traps (plastic cups with 4% formaldehyde, inserted into the depths 5–95 cm through a plastic tube), which were checked monthly. Almost 26,000 specimens were trapped. Arthropods highly dominated over gastropods and earthworms. Collembola (67.61%) and Acarina (15.55%) were eudominant. Macrofauna was represented mainly by larvae of Holometabola (7.55%) and adult Diptera (5.11%) and Coleoptera (1.13%). All these groups were captured along the total depth gradient. Coleoptera were studied in more details. Among 11 Coleoptera families, Staphylinidae predominated and were captured at all levels. Rather high species diversity was found: 67 spp. excluding common epigeic fauna. Some species supposed to be subterranean, e.g., Bryaxis frivaldszkyi slovenicus, Duvalius bokori valyianus and Omalium validum. Activity of most invertebrate groups decreased significantly with depth (prevalence of surface fauna), but it was not terminated at 1 m under surface; the same was true for beetles, both in activity and diversity. Conspicuous fact is that a mass of subterranean species were traced also close to the surface (35 cm), i.e., probably it is not necessary to put the traps as deep as in this study. Seasonal climate changes affected the activity of invertebrates which was the highest at the end of spring and the lowest during winter, but it was not completely interrupted. Microclimate was characteristic without major temperature fluctuations on the surface. It was stable deeper along with increasing average annual temperature. High diversity and the occurrence of rare faunistic elements as well as specific habitats of MSS are perspective study objects and they merit care; mature design of the next studies considering the effect of season and depth of traps deposition shall do them more effective and less laborious. Key words: mesovoid shallow substratum; invertebrates; Coleoptera; vertical distribution; diversity; temperature regime; seasonal dynamics; limestone scree; Slovakia

Introduction The concept of Mesovoid Shallow Substratum (originally in French, milieu souterrain superficiel, MSS) was defined by Juberthie et al. (1980). It consists of a system of empty ventilated spaces within the stony debris covered by soil. This formation is in most cases the result of frost weathering in temperature zone. Rock fragments accumulate in several layers on the bedrock. In the final phase they are covered by a layer of soil, which isolates the MSS from the surface and makes it a stable environment with conditions close to those in caves (Juberthie 2000; Giachino & Vailati 2010). This habitat was studied mainly in temperate mountain ranges (Culver & Pipan 2009) in both carbonate and non* Corresponding author

c 2012 Institute of Zoology, Slovak Academy of Sciences


carbonate rocks (Juberthie et al. 1980; Juberthie & Delay 1981; Camacho 1992). Parameters that affect biodiversity in MSS are thickness of soil layer, density of vegetation cover and especially the flow of organic carbon, which is stronger than in the cave, extension and continuity of subterranean spaces (Gers 1998; Pipan et al. 2011). Network of cracks within the bedrock represented a suitable shelter for surviving of invertebrate fauna during the last glaciation. Close contact with the surface and stable conditions made the MSS an environment that is more attractive and especially more affordable for fauna and finally more spacious than caves. The adaptation of animals to hypogean environment may also be in progress in this transition zone (Pipan et al. 2011; Růžička 1993, 1999). There is an assump-

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Table 1. Some characters of yearly temperatures at the study plot ( ◦C). The months are marked by Roman numerals. Depth

Max

Surface 15 cm 35 cm 55 cm 95 cm

20.5 18.5 17.5 17.5 16.0

Min (VII) (VII) (VII) (VII–VIII) (VIII)

–4.0 1.0 1.5 2.5 3.5

(I) (III) (II–III) (II–III) (II–IV)

Range

Average

24.5 17.5 16.0 15.0 12.5

7.9 8.6 7.9 9.1 9.3

tion that the obligate cave fauna became semi-extinct in Central Europe during the period of glaciation which caused noticeable regional and latitudinal differences in its distribution (Culver et al. 2006). The subterranean spaces with the occurrence of troglobionts are abundant mainly in the Mediterranean region (Gers 1988; Pipan et al. 2011) while adapted surface fauna with presence of relics prevails in the northern regions, especially with cold even permafrost type of MSS (Christian 1987). The type of rock has probably no influence on the specialized subterranean fauna (Giachimo & Vailati 2010). Invertebrates dwelling MSS were studied mainly in Europe, especially in France, Romania, Slovenia, Austria and the Czech Republic or in the Canary Islands, focused on some model groups, such as beetles (e.g., Gers 1986, 1988; Nitzu et al. 2007; Giachino & Vailati 2010), oribatid mites (Arillo et al. 1994), spiders (Nae & Ilie 2004; Růžička & Zacharda 2010; Laška et al. 2011), centipedes (Ilie 2003a, b), springtails (Gers & Najt 1983; Querner & Krenn 2005) and flies (Gers 1993) or occasionally on the full invertebrate communities (e.g., Nitzu et al. 2010). The objectives of this study were to investigate the MSS dwelling invertebrate community in the karstic part of the Čierna hora Mts (the Western Carpathians Mts), as the northernmost area of the obligate cave fauna in Central Europe and to monitor the spatial and seasonal aspects of both microclimate and invertebrates. Selection of the locality was based on the regional cave fauna inventory (Mock et al. 2009). We presumed that comparisons between communities and well-adapted species in both habitats, caves and scree slopes could lead to a more complex understanding of the subterranean environment functioning. Material and methods The research was conducted at one of the MSS sites (geographic co-ordinates 48◦ 50 31.27 N and 21◦ 06 33.97 E) in the National Nature Reserve (NNR) Sivec, the Western Carpathians Mts (eastern Slovakia). A massif of Mesozoic limestone with steep debris at its base is the typical feature of the reserve territory. The study plot is located at 530 m a. s. l., a few metres under the top of the slope on the foothill of rock faces. The north-east scarred slope is close to the valley and it is covered by the linden-maple forest (Tilio-Acerion). During the winter season the area is usually covered by snow. Invertebrates were collected by subterranean traps designed based on Schlick-Steiner & Schlick (2000) and Laška et al. (2008): 110 cm long PVC pipe (ø 110 mm) with 10 ver-

Max 1-day contrast 5.5 1.0 1.0 0.5 0.5

(IV)

tical levels (5, 15, 25, 35, 45, 55, 65, 75, 85 and 95 cm) where plastic cups were fixed as traps and small holes (ø 7 mm) were drilled around to pipe to allow the entry of invertebrates into the traps. Top of the pipe was covered with tin plates. The traps (volume 500 ml) were made of a flexible plastic, fixed on the moving central iron staff and filled with 4% formaldehyde for fixation. Triplicate of traps (or pipes) were dug in line, at a distance of 30 cm and traps were controlled monthly from October 2008 to November 2009. The obtained material was later fixed in alcohol and gradually identified to the level of higher taxa and Coleoptera to the species level using identification keys. The beetle nomenclature was according to Fauna Europaea (2011). Animals are deposed in the authors’ collections. Two series of thermodataloggers (iButton DS 1921G #F50 Maxim Dallas, USA) were used for long-term and continuous measurement of temperature (four-hour intervals). The temperature was measured at five levels: on the surface and inside the debris at depths of 15, 35, 55 and 95 cm.

Results Temperature regime The largest temperature fluctuations were observed on the surface. Deeper under the surface, only long-term fluctuations were registered, the amplitudes were lower in depth, but synchronised with the climate dynamics on the surface (Table 1, Fig. 1). On the soil surface, the temperature decreased below zero only for short periods in contrast to rather strong freezes in the air above the surface (more days with less than –10 ◦C). Deeper than 15 cm no frost occurred. Average annual temperature increased along the vertical gradient in contrast to maximum day temperature. Activity and seasonal dynamics of invertebrates along the vertical gradient Almost 26,000 individuals of 24 higher invertebrate taxa were collected, and more than 99.8% of individuals belonged to Arthropoda; some earthworms and gastropods were collected besides the major groups. Mesofauna, especially Collembola, was highly predominant over macrofauna; more than 83% of all individuals belonged to it. Adult Diptera and Coleoptera and the larval stages of several groups of holometabolic insects belonged to the dominant groups, exceeding 5% (Table 2). Majority of the individuals of all groups (60%) was trapped at 5 cm under the surface. Only eight higher taxa were distributed along the entire vertical gradient and 14 taxa were found in a depth of 95 cm. Besides

Invertebrates dwelling karstic mesovoid shallow substratum

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Fig. 1. Daily average fluctuations of air temperature within MSS at different depths.

Thysanoptera

Heteroptera

Auchenorrhyncha

33 3 1 0 9 2 6 8 20 13

0 0 0 0 0 0 0 0 0 1

19 1 0 0 2 0 0 0 0 0

0 0 0 0 1 0 0 0 0 0

0 1 0 0 0 1 0 0 0 0

9 3 1 0 1 0 0 0 0 0

Total

28

7

26 117

18 4039

26

1

4

69

97 17561

95

1

22

1

2

14

22 237 19 24 9 5 1 1 5 2 6 1 11 8 9 4 5 7 4 4

41 14 11 5 6 4 17 3 7 6

56 1 0 0 0 0 0 1 0 1

1 0 0 0 0 0 0 0 0 0

247 113 30 38 57 96 175 175 215 182

91 293 114

59

1 1328 1961 25973

Total

Psocoptera

43 11454 9 2635 6 602 0 275 1 401 3 358 14 559 3 384 12 397 6 496

Larvae

Plecoptera

42 4 5 1 2 3 3 3 4 2

Diptera

Diplura

0 2 0 1 0 1 0 0 0 0

Mecoptera

Chilopoda

0 0 0 0 0 1 0 0 0 0

Formicoidea

Pauropoda

21 0 1 0 1 2 1 0 0 0

Hymenoptera

Symphyla

18 2752 0 361 0 165 0 141 0 92 0 142 0 104 0 92 0 95 0 95

Coleoptera

Isopoda

96 3 3 0 2 3 3 3 1 3

Aphidinae

Araneae

17 5 1 1 0 0 2 0 0 0

Collembola

Pseudoscorpiones

5 1 0 0 0 0 0 1 0 0

Diplopoda

Lumbricidae

17 3 2 0 1 1 2 0 1 1

Acarina

Gastropoda

5 15 25 35 45 55 65 75 85 95

Opiliones

Depth (cm)/Taxon

Table 2. Overall distribution of higher taxa of invertebrates along the vertical gradient.

427 15557 109 3311 72 914 88 552 177 760 151 774 278 1182 221 907 246 1010 192 1106

D % 0.11 0.03 0.10 0.45 0.07 15.55 0.09 0.00 0.02 0.27 0.37 67.61 0.37 0.00 0.08 0.00 0.01 0.05 0.35 1.13 0.44 0.23 0.00 5.11 7.55 100.00

the regular occurrence of some invertebrate groups, Symphyla, Plecoptera, Thysanoptera, Mecoptera and scorpionflies were sporadically present, and harvestmen were caught only at the surface. Both high taxa diversity and specimen number declined strongly within the zone between –5 and –35 cm, then the decrease of both parameters stopped and other horizons showed equal characteristics, sometimes even with moderate increase (Fig. 3). Deeper, the structure of invertebrate communities changed, springtails highly predominated but their ratio slightly decreased with depth (from 74% to 51%), while the relative abundance of adult dipterans and insect larvae increased.

Seasonal climate changes affected the activity of invertebrates. Fluctuations of the locomotion activity (=presence in traps) during the year were observed in all dominant groups and at all depths (Fig. 3). In general, the activity culminated twice, during spring and autumn (summer and beginning of winter in Acarina and adult Diptera, respectively). These fluctuations were observed along the depth gradient within the talus, sometimes with moderate short-time decreases at deeper levels. The activity of some arthropods (Coleoptera, Diptera) was interrupted during the winter and summer period, in winter for longer period, nevertheless the activity of the other invertebrates

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Fig. 2. Monthly fluctuations of the activity of dominant groups of invertebrates.

Fig. 3. Overall activity (number of individuals) and the number of higher invertebrate taxa along the vertical gradient.

(e.g., Collembola and Acarina) dropped only slightly (Fig. 4). Species diversity and seasonal dynamics of activity of Coleoptera A total of 67 species of Coleoptera were captured (Table 3). Staphylinidae was the most diversified among the 14 families (36 spp., 53.7%) and inhabited the entire vertical gradient (Table 4). Five staphylinid species predominated over the rest, each of them participated with more than 5% in the community abundance: Liogluta microptera (Thomson, 1867), Omalium rivulare (Paykull, 1789), O. rugatum Mulsant & Ray, 1880, Bryaxis nigripennis (Aubé, 1844) and Lath-

robium fulvipenne (Gravenhorst, 1806) (Table 3). In general, the overall activity, species and family richness decreased with the depth from –5 to –35 cm. 58 spp. (85.3%) were recorded at 5 cm under the surface, while only 14, 4 and 1 species were found at –15 cm, –25 cm and –35 cm, respectively. Thus, more than 95% of species occurred between the depths of –5 to –35 cm. Deeper under the surface all mentioned parameters showed low values, their changes had no linear character and at the bottom of the vertical gradient they even rose slightly. Only 9 spp. (12.2%) dwelled deeper than –35 cm, three of them (4.4%) were found exclusively there: Anaspis sp., Duvalius bokori valyianus (Bokor, 1922) and Eusphalerum

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Table 3. Diversity and spatio-temporal distribution of Coleoptera. Taxon 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67.

Abax ovalis (Duftschmid, 1812) Abax parallelepipedus (Piller et Mitterpacher, 1783) Acrotona troglodytes (Motschulsky, 1858) Acrotrichis intermedia (Gillmeister, 1845) Adexius scrobipennis (Gyllenhal, 1827) Agathidium laevigatum laevigatum Erichson, 1845 Agriotes pilosellus (Sch¨ onherr, 1817) Amphichroum canaliculatum (Erichson, 1840) Anaspis sp. Anthobium atrocephalum (Gyllenhal, 1827) Anthobium melanocephalum (Illiger, 1794) Anthophagus bicornis (Block, 1799) Atheta fungi (Gravenhorst, 1806) Atheta putrida (Kraatz, 1856) Atomaria sp. Bryaxis frivaldszkyi slovenicus (Machulka, 1926) Bryaxis nigripennis (Aubé, 1844) Catops fuliginosus fuliginosus Erichson, 1837 Catops sp. Catops subfuscus subfuscus Kellner, 1846 Cephenium majus Reitter, 1881 Colon affine Sturm, 1839 Cryptophagus sp. Denticollis linearis (L., 1758) Dienerella elongata (Curtis, 1830) Duvalius bokori valyianus (Bokor, 1922) Euconnus (Cladoconnus)denticornis (M¨ uller et Kunze, 1822) Euconnus transsilvanicus (Saulcy,1876) Eusphalerum longipenne (Erichson, 1839) Eusphalerum rectangulum (Baudi di Selve, 1870) Eusphalerum semicoleoptratum (Panzer, 1795) Gymnetron sp. Habrocerus capillaricornis (Gravenhorst, 1806) Chrysomelidae sp. Ischnosoma longicorne (M¨ aklin, 1847) Lathrobium fulvipenne (Gravenhorst, 1806) Leiodes sp. Liogluta granigera (Kiesenwetter, 1850) Liogluta microptera Thomson, 1867 Medon fusculus (Mannerheim, 1830) Meligethes aeneus (F., 1775) Molops piceus piceus (Panzer, 1793) Nargus velox (Spence, 1815) Neuraphes elongatulus (M¨ uller et Kunze, 1822) Ocalea badia Erichson, 1837 Ocypus macrocephalus (Gravenhorst, 1802) Omalium rivulare (Paykull, 1789) Omalium rugatum Mulsant et Rey, 1880 Omalium validum Kraatz, 1857 Othius punctulatus (Goeze, 1777) Oxypoda acuminata (Stephens, 1832) Oxypoda alternans (Gravenhorst, 1802) Oxypoda formosa Kraatz, 1856 Oxypoda vittata M¨ arkel, 1842 Parabolitobius inclinans (Gravenhorst, 1806) Proteinus brachypterus (F., 1792) Proteinus crenulatus Pandellé, 1867 Pterostichus burmeisteri Heer, 1841 Pterostichus foveolatus (Duftschmid, 1812) Pterostichus oblongopunctatus (F., 1787) Ptomaphagus variicornis (Rosenhauer, 1847) Quedius fumatus (Stephens, 1833) Quedius mesomelinus mesomelinus (Marsham 1802) Quedius sp. Quedius suturalis Kiesenwetter, 1845 Rhizophagus dispar (Paykull, 1800) Scaphisoma assimile Ericson, 1845 Tachinus laticollis Gravenhorst 1802 Trimium carpathicum Saulcy, 1875 Total

Family C C S P Cu L E S Scr S S S S S Cr S S L L L Sc L Cr E L C Sc Sc S S S Cu S Ch S S L S S S N C L Sc S S S S S S S S S S S S S C C C L S S S S M Sca S S

Ind.

D (%)

Depth (cm)

Months

10 5 3 2 2 1 2 4 3 9 1 3 4 5 1 4 20 1 1 1 2 1 4 1 1 1 1 2 3 4 1 1 8 2 1 17 1 11 29 2 2 14 1 1 4 1 27 20 1 6 2 1 4 3 1 1 3 13 1 1 1 1 1 1 2 1 1 1 2

3.41 1.71 1.02 0.68 0.68 0.34 0.68 1.37 1.02 3.07 0.34 1.02 1.37 1.71 0.34 1.37 6.83 0.34 0.34 0.34 0.68 0.34 1.37 0.34 0,34 0.34 0.34 0.68 1.02 1.37 0.34 0.34 2.73 0.68 0.34 5.80 0.34 3.75 9.90 0.68 0.68 4.78 0.34 0.34 1.37 0.34 9.22 6.83 0.34 2.05 0.68 0.34 1.37 1.02 0.34 0.34 1.02 4.44 0.34 0.34 0.34 0.34 0.34 0.34 0.68 0.34 0.34 0.34 0.68

5, 25 5, 25 5, 35 5 5, 15 5 5 5 85 5 5 5, 15 5 5 5 5, 65, 85, 95 5, 15 5 5 5 5 5 5 5 15 65 5 5 75 5 5 15 5, 15 15, 25 5 5–25, 45–95 5 5 5, 15, 85 15, 75 5, 95 5, 15 5 5 5, 15 5 5 5 15 5, 15 5 5 5, 15 5 5 5 5, 45 5, 15 5 5 5 5 15 5 5 5 5 5 5

V, VII, IX, XI V, VI VI, X V, VII VIII, XI VIII VII V,VI VII, VIII, IX V, VI, VIII, XI V V–VII V–VII XI XI V–VII, XI V–VII, IX, X XI X V V IX VI, VII, IX VII XI V V V, VI VI, VII VI, VII VII VIII VI, VII, XI VIII,X VI VI-VIII VII X V-VII,X,XI IX V,VII V-VII,IX-XI IX V X, XI V V–VII, XI V–VII X I, II, IV, V, XII XI X X, XI XI IV V XI IV–VIII, X, XI V V VII VII V V V, XII IV X VIII VI

293

100.00

Explanations: Abbreviated names of familes: C – Carabidae, Ch – Chrysomelidae, Cr – Cryptophagidae, Cu – Curculionidae, E – Elateridae, La – Latridiidae, L – Leiodidae, M – Monotomidae, N – Nitidulidae, P – Ptiliidae, S – Staphylinidae, Sc – Scydmaenidae, Sca – Scaphidiidae, Scr – Scraptiidae.

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M. Rendoš et al.

Fig. 4. Monthly fluctuations of activity of the main invertebrate groups observed along the vertical gradient (logarithmic transformation).

Table 4. Structure of the complete beetle assemblage at the family level. Family 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.

Number of species

D (%)

inds

D (%)

Carabidae Chrysomelidae Cryptophagidae Curculionidae Elateridae Latridiidae Leiodidae Monotomidae Nitidulidae Ptiliidae Staphylinidae Scydmaenidae Scaphidiidae Scraptiidae

7 1 2 2 2 1 7 1 1 1 36 4 1 1

10.45 1.49 2.99 2.99 2.99 1.49 10.45 1.49 1.49 1.49 53.73 5.97 1.49 1.49

45 2 5 3 3 1 8 1 2 2 211 6 1 3

15.36 0.68 1.71 1.02 1.02 0.34 2.73 0.34 0.68 0.68 72.01 2.05 0.34 1.02

Total

67

100.00

293

100.00

longipenne (Erichson, 1839), belonging to different families. On the family level, the highest diversity was concentrated at surface of the debris (–5 to –35 cm), only four of them were present at deeper levels: Carabidae,

Nitidulidae, Scraptiidae and Staphylinidae, with the predominance of members of the latest family (66.7% of species) (Fig. 5). During the year, clear maximum of the total beetle activity was measured in the trap controls from May to July (e.g., during the months be-

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Fig. 5. Relative abundance, species and family richness of Coleoptera along the vertical gradient.

fore the true controls). Among 47 spp. (29 spp. exclusively), captured in this period, also some of specific representatives of the underground were collected (e.g., D. bokori valyianus, Bryaxis frivaldszkyi slovenicus (Machulka, 1926)), but the other 20 species were active only out of this period (Table 3). Discussion Specific climate characteristics within the scree slopes have been studied by several authors (e.g., Nitzu et al. 2007; Zacharda et al. 2007; Pipan et al. 2011). The basic characteristics of the year-round temperature regime is transient there compared to static cave spaces and surface (soil); it is more stable than on the surface but still clearly influenced by seasonal fluctuations. Such conditions can be considered as suitable for adaptive processes leading to the obligate underground strategy of life (like subterranean species) and moderate climate within the slope can be used as refuge by relict fauna, locally supported by the presence of such representatives of millipedes and springtails in the scree (Rendoš et al., unpublished). In general, this phenomenon was confirmed mainly in forested slopes or in the MSS covered by a huge soil layer (Pipan et al. 2011). Even the type of slope debris that was investigated in this study strongly impacts the surface climate in de-escalation of extreme values of temperature in summer or winter, considering the fact that its surrounding has also peculiar conditions (the slope is “breathing”). In deeper horizons more stable and increased temperature were observed. The study plot was situated at the upper part of the slope, which is under the influence of warmer air deposited within the scree (Růžička & Růžička 1990; Růžička 1993). The lower winter temperatures were only slightly below zero, although during January the air temperature was under –10 ◦C and rather huge layer of snow covered the sur-

face. On the contrary, bases of scree slopes can be permanently cooled even as permafrost in such cases and these are typical climatic anomalies of slope deposits and their close surroundings. The climatic characteristics of such habitats are equal to those that are typical of other altitudes or latitudes than the site under investigation, thus it is a potential refuge for organisms (Zacharda et al. 2007). Favourable microclimate without extreme temperatures enabled uninterrupted activity of invertebrates during the whole year. Warmed underground up to the surface probably caused that no vertical migration of fauna was observed. In addition, no retardation of seasonal activity at any of the investigated levels was observed. There is no general agreement about the depth of border between soil and MSS. For example, on the Canary Islands traps with 75 cm long plastic tubes were used and troglomorphic invertebrates were recorded (López & Oromí 2010). Querner & Greben-Krenn (2005) used only 50 cm tubes and they also recorded some troglophilous springtails at various depths. At the site investigated in this study the maximum thickness of organic soil and rhizosphaera run to the depth of 35–45 cm and a mixture of stones and mineralised soil followed, except for solitary roots which overgrew to a depth of several metres. The distribution pattern with typical sudden decline of activity of majority of invertebrates (and species diversity) along the depth gradient is probably caused by rapid limitation of food sources and open spaces. Gers (1993, 1998) observed that the distribution of fauna in MSS was induced by accessibility of food (dead plant material), which was concentrated at the surface and during rainfall it was distributed deeper under the surface. The occurrence of some species is aggregated, e.g., flies and their larvae (Gers 1993). We did not recognize aggregation of any taxa, except of the general concentration of majority of the specimens close to the surface. The distribution and activity of insect

1150 larvae was vertically continuous; more surprising was a rather continuous vertical distribution of adult flies and hymenopterans (mainly small body forms without reduced wings). Deep penetration of plant louses can be explained by deposition of food sources (long roots of trees). Dry periods prevented water transport of organic material deeper to the underground. Availability of food, which is not continuous and permanent over the year, can essentially influence activity and reproduction of animals in the MSS (Gers 1998). Cone-like distribution pattern is characteristic by a strong drop in the number of trapped individuals along the vertical gradient, especially at two uppermost levels. This trend extends to 35 cm under the surface. Deeper, the activity of animals is rather constant. In some of them the total vertical distribution is more like the shape of a sandglass, most markedly in Diptera or Diplura. Expressive dominance of mesofauna (mites and springtails) was expected, however, compared with similar studies the peculiarities of particular sites are distinguished. In some cases deep and continuous penetration of bigsized arthropods as well as lower relative abundance of mesofauna were observed (Laška et al. 2011). The differences are probably due to peculiarities of the regional fauna and its potential to colonise the underground (Pipan et al. 2011) and differences in topography, latitude, altitude, vegetation, exposition of the slope, but some contrasts can be subjective (e.g., differences in methodology). Seasonal dynamics of invertebrate activity within the slope followed changes in temperature, and there is no evidence of occurrence of abundant species independent of oscillation of climatic variables, which is in contrast with cave inhabitants which lost the seasonal rhythm (Culver & Pipan 2009). However, in this phase of investigation we are not able to exclude the occurrence of subterranean forms with other temporal model of activity, but based only on Coleoptera. These species are rare and can be caught only sporadically, being impossible to rate. Slight differences among the seasonal activity of single groups of invertebrates were observed in this study. The activity of dominant groups culminated rather steeply during late spring months (Collembola, Coleoptera), summer months (Acarina) to September (Diptera) and then it strongly decreased, probably due to the dry period. Seasonal fluctuations of activity in adult dipterans are probably caused by the end of the larval development during the maximum precipitation period (June–July) and consecutive incubation of adults. Close to the surface, both increase and decrease in seasonal activity of invertebrates were more sudden and shorter in time in comparison with those at deeper levels, except for Diptera, where the aestival peaks (at –65 cm, –85 cm, –95 cm) were the highest. Winter decline was longer than the aestival one (up to 4 months), but the activity of some invertebrates was continuous during all seasons, completely interrupted only in some cases and levels for a short period.

M. Rendoš et al. Coleoptera is the first model group we studied at species level. Their relative activity was rather low, but based on the partial unpublished data on other invertebrate groups, beetles are the group with the highest species richness dominating other groups of macrofauna that occurred within the scree. High species richness (alpha diversity) was recognized and high value of diversity index (Shannon’s index = 3.56, Simpson’s index 1–D = 0.96) have premised total local diversity will be higher in reality. Nevertheless such high biodiversity with absence of obligate subterranean forms has shown the upper horizons of scree habitat could be supposed as surface-subterranean ecotone. Deeper from –15 cm it is continuously converted into true MSS. In comparison with 20 caves and cavities in the same orographic unit several collectors used a combination of collecting methods during multi-year investigation and they found only 50 species (15 families), although diversity of families was higher in the caves (Mock et al. 2009). In both types of underground, caves and under the surface of scree slope the family Staphylinidae predominated, followed by small-sized representatives of other families (except of cave entrances with large-sized epigeic beetles). Beetles belong especially to the “surface” species without specific adaptations to life underground, however, there were no large epigeic forms (Anoplotrupes, Carabus spp. et al.), and even if no specific “MSS forms” or troglobite was found, some troglophilous species were present, e.g., the common Quedius mesomelinus or the infrequent Bryaxis frivaldszkyi slovenicus, B. nigripennis, Omalium validum and Duvalius bokori valyianus. But there is probably no potential for the occurrence of obligate troglobitic beetles in the whole West Carpathians (Košel 2009). In comparison with the local cave fauna, in the scree slope there is an absence of some important species (e.g., Atheta spelaea or Duvalius hungaricus), but their distribution pattern is discontinuous, they were recorded in different parts of the Čierna hora Mts (Mock et al. 2009) and there is no evidence of any troglobitic beetles in the Western Carpathians. From the faunistic point of view, the presence of some species is remarkable. B. frivaldszkyi slovenicus and D. bokori valyianus are endemic for the neighbouring part of the West Carpathians and they prefer subterranean habitats. A bulk of the species showed simple pattern of seasonal activity similar to other groups of terrestrial arthropods in temperate forests in general: two peaks yearly, especially the spring-summer one is massive. It can be a good tool for faunistic short-time research: most of the beetles can be collected in the “fruitful” late spring period close to surface. But there are many scattered species dwelling deeper levels and occurring as adults in different seasons. Acknowledgements The study was supported by the grant Vega 1/0139/09. Authors express great thanks to Dr. P. Ľuptáčik, J. Rendoš, M. Goga, E. Miková, S. Kuchár (Košice) for the help during field works, Dr. P. Ľuptáčik also for checking of tempera-

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