Роль природно-заповідних територій у підтриманні біорізноманіття. Матер. конф., присвяч. 80-річчю Канівського природн. запов. м. Канів, 9-11 вересня 2003 р. Канів, 2003. С. 260-262

TO THE STUDY OF THE ARANEOFAUNA OF THE DNIEPROVSO-ORELSKY NATURE RESERVE (DNEPROPETROVSK AREA, )

The Dnieprovsko-Orelsky Nature reserve is situated near Dnepropetrovsk City at the confluence of the Orel and Dnieper rivers, and is distinguished by its extremely high habitat diversity: reed-beds, riparian biotops of different types, flood land oak forests and poplar stands, mixed and coniferous forests, meadows, sandy steppes and others. The inventory of the araneofauna of this locality has not been carried out earlier. As a result of our investigations in May-August 1997-1998, 151 species from 21 families were registered. There are no predominating families in this local fauna. The Linyphiidae family is the most numerous, but it makes up 17%, while Araneidae comprises 12%, Salticidae 11%, Theridiidae 10%, Gnaphosidae 10%, 9%, Lycosidae 8% etc., 4 families are represented by only 1 species. communities of the oak forest are the most diverse – 91 species. Mainly these species are widespread in oak forests of the forest-steppe and steppe natural zones, and even the bulk of dominants is common. In the herbage of the dark shadowy cuttings, 7 species predominate (Enoplognatha ovata Cl., Linyphia hortensis Sund., L. triangularis Cl., Tetragnatha pinicola L. K., T. montana Sim., Araneus diadematus Cl., Metellina segmentata Cl.); Mangora acalypha Walck. and piger Walck. join them in more open alight places. The difference is in the absence of Helophora insignis Bl., Philodromus dispar Walck. and Lepthyphantes angulipalpis Westr.; in changing of Clubiona caerulescens L. K. to C. lutescens Westr.; and in number decreasing of Haplodrassus silvestris Bl., Microneta viaria Bl., and Entelecara acuminata Wider. The main part of the Linyphiidae found in the nature reserve occurs in the litter of this biotope. Abacoproeces saltuum L. K., Macrargus rufus Wid., Lepthyphantes flavipes Bl., Maso sundewalli Westr. are dominants. Dynamic density of such litter dwelling species as Pardosa lugubris Walck. and Zora spinimana Sund. increases from the old dark oak stand to the young open one, while dynamic density of Pachygnatha listeri Sund., Ozyptila praticola C. L. K., Trochosa terricola Thor., Abacoproeces saltuum decreases. The quantity of Xysticus cambridgei Bl. does not change. On the glades and forest edges, the dominant complex changes and consists of Terentula pulverulenta Cl., Haplodrassus umbratilis L. K., H. signifer C. L. K., Titanoeca schineri L. K., rare under the canopy. The maximum of the spider density in the litter was registered in the old oak forest (64 ind./m2), while the number in the herbage was the highest in the young forest (50 ind./100 sweeps), on average per season, with the peak in August (105 ind./sample). Species composition is also more diverse in the young open forest (63 species), in the old one it diminishes due to the poor light intensity and the absence of the herb layer (29). The same factors stipulate the typical features of the spider complexes of black poplar stands: poor species composition (23 sp.), the Linyphiidae predominance, and high spider density in the litter (43 ind./m2). In the plots of white poplars, in the dense alighted herbage, the araneocomplexes are mixed, represented by species typical of both, oak forest and steppe habitats. There occur photo-and xerophilous Uloborus walckenaerius Latr., Oxyopes heterophthalmus Latr., Cheiracanthium pennyi O. P.-C., Steatoda meridionalis Kulcz., Theridion innocuum Thor., Neoscona adianta Walck., with predaminating Dictyna arundinacea L., Agelena labyrinthica Cl., Evarcha arcuata Cl., Tarentula pulverulenta. This fact integrates the faunas of the poplar stand, steppe and pine forest. On the other hand, recording of Enoplognatha ovata, Diplocephalus picinus, Trematocephalus cristatus Wid., Tetragnatha montana, T. pinicola and a high number of Pardosa lugubris are typical of the oak stands. The main distinguishing character of this biotope is a great amount of Linyphia triangularis, which weaves densely the bush and grass layers. In pine forests, as in the other forest types, species composition and spider number depended on light intensity and understory development. In old dark plantations without bush and grass layers, spider fauna numbered only 15 species. Araneus diadematus Cl., A. angulatus Cl., Cyclosa conica Pall., Dictyna uncinata Thor., Theridion varians Hahn and others occupied the canopy; in needle litter we collected rear Crustulina guttata Wider, Lepthyphantes flavipes, Agyneta rurestris C. L. K., Stemonyphantes lineatus L., and more numerous Steatoda meridionalis, Titanoeca schineri, Agelena labyrinthica, Zelotes subterraneus C. L. K. Pholcus ponticus Thor., usually a synantropic species, was found in a stub. In the light pine forest, spider community was, vice versa, rich and diverse (45 species). The edges and glades were populated densely (45 ind./100 sweeps). Mangora acalypha, Neoscona adianta, Evarcha arcuata, Theridion simile C. L. K., Gibbaranea bituberculata Walck., Dictyna arundinacea, Argiope bruennichi Scop. were numerous, while Agalenatea redii Scop., Cyclosa oculata Pall., Gibbaranea ullrichi Hahn, Uloborus walckenaerius, Theridion impressum L. K., Cheiracanthium pennyi, Philodromus histrio Latr., Heliophanus flavipes Hahn, Enoplognatha ovata, Linyphia triangularis were common. Evidently, the bulk of dominants are wider, than that in the oak forest. In the dark pine forest with Gledichia and herb layer, two tendencies may be observed: first, a replacement of a photo- and xerophilous complex with a mesophilous one, with Tetragnatha pinicola and Metellina segmentata as dominants, and Anyphaena accentuata Walck., Linyphia hortensis, Tmarus piger, Heliophanus cupreus Walck., Araniella displicata Henz. recedents; and second, an increase of Enoplognatha ovata and Linyphia triangularis number. They are polytopic species preferring shadowy forests. As a result, the araneocomplex becomes closer to that of the oak forest. Altogether we found 68 spider species in the pine forests. In steppe habitats, there were 58 species recorded. A complex of the grass-dwellers wad formed by the same species as in the pine forest glades, but the ratio of dominants changed significantly. The quotient of Mangora acalypha, Evarcha arcuata, Theridion simile decreased, while that of Agalenatea redii, Uloborus walckenaerius, Neoscona adianta, Cyclosa oculata, Gibbaranea ullrichi, Cheiracanthium pennyi increased, Linyphia triangularis, Enoplognatha ovata, Gibbaranea bituberculata changed their position to recedents. The average spider density was high, 45 ind./sample, with a maximum in June (80 ind/sample). Spider assemblages in litter are more diverse in the steppe, than in the pine forest, 28 species. The most common are Gnaphosa mongolica Sim, Zelotes electus C.L.K., Z. longipes L. K., Callilepis nocturna L. In 1998, a small part of the steppe was burnt down. In May 1999, in the scarse grass only rare Dictyna arundinacea, Theridion simile, Neoscona adianta, Xysticus cristatus Cl. were collected. Herpetobium, on the contrary, was settled rapidly. In May, in both burnt and unburnt plots, the same species occurred, and even the dynamic density was similar (3,2 – 3,5 ind./10 trap-days, respectively). On the whole, species composition of the burnt plot turned out to be poore, because a big part of intact steppe was situated in a depression not far from a small lake, and some atypical of the steppe species get from a neighboring biotope (Pardosa lugubris, Trochosa terricola, T. ruricola De Geer, Haplodrassus umbratilis). The herbage had been inhabited fully to July. As a rule, northern elements invade southern climatic zones along the flood land ecosystems, while in steppe and pine habitats species with southern origin occur. In the investigated locality, there were an East European - Central Asian species Sitticus innopinabilis, Logunov, two Pontics Gnaphosa moesta (, Rumania, Crimea), and Steatoda meridionalis (Hungary, , , , Georgia) found. The latter occurs in Ukraine in the Kharkov, Poltava, Kherson Regions, and eastward is replaced by the widespread S. phalerata. A Eurasian steppe species, Gnaphosa mongolica, in Ukraine is common in the South of the Kherson Region, only once it is found on sandstone outcrops in Lugansk Region, and, at last, in sandy steppe of the Dnieprovsko-Orelsky nature reserve. Furthermore, we recorded here quite rare, locally occurring in Ukraine Aelurillus v-insignitus Cl., Asianellus festivus C. L. K., Sitticus zimmermanni Sim., Synageles lepidus Kulcz., Theridion innocuum, Ceratinopsis romana O. P.-K. Thus, a unique araneocomplex is being formed in the steppe, and demands strict protection.