THE CHANGE OF ZOOCOENOTIC CHARACTERISTICS OF GROUND-BEETLE COMMUNITIES UNDER THE INFLUENCE OF GRAZING HORSE ON FLOODPLAIN MEADOWS IN BELARUS

Leonora KHOTKO

«Scientific-practical Center of the National Academy of Sciences of Belarus for biological resources», Akademicheskaya str., 27, Minsk, 20072, Belarus, e-mail: khotko1@yandex.ru

Key words: ground beetles, dominance, meadows, abundance, dominant species.

Abstract: The investigations on the change of  the degree of ground beetle environmental similarity, of  the degree of the relative habitat timing and species dominance were carried out in the Minsk district in 2011. During the study period 5198 traps/days were processed, 6024 specimens of ground-beetles were determined. In addition, it is established that during the growing season the number of species in grazed plots compared with initial ones did not change - 34-51 species. Only the composition of species changed. As a result of studying species composition and zoocoenotic indicators of ground beetle communities 83 species living on floodplain meadows were revealed. Of the ecological groups selected on relation to humidity the greatest number of species on floodplain meadows presented mesophiles, and after grazing I, obviously, with rainfall gigrophiles were. On the basis of biotopic distribution we took these species to 8 ecological groups. Field species were characterized by the most number, sometimes their abundance reached 54 %. The majority of ground-beetle species (82,3 %) bred in the spring and in the beginning of summer. Species of multiseasonal phenological group weren't numerous (5,9 % – 26,5 %), and summer and summer-and-autumn groups were random (2,6 % - 11,8 %). It was explained by migration of “nearwater” mesophile species, which made a considerable part in fauna, from a spring high water to adjacent biotopes.

1. Introduction

Ground-beetles are an important component of soil fauna and occupy one of the leading positions in all land biogeocenoses, both on number of species, and by quantity of individuals in populations. They are a quite large group of coleoptera in a systematic respect and one of the most important groups in practical terms. They occur everywhere and have a high diversity of species (about 308 described species in the fauna of Belarus). Ground-beetles are sensitive enough to anthropogenic pressure, which makes them rather expressive and convenient material for biocenotic research and selection of biological indicators of ecosystem state among them. The complexes of ground-beetles on meadows of the forest zone are studied well enough [1-3].

In Belarus studied the complexes of ground-beetles on meadows [4-7]. There are stud farms for breeding horses in Belarus. It is necessary to graze horses for feeding on meadows, including floodplain ones. Studies on the influence of grazing horses on the ground-beetle communities in Belarus were not previously

carried out.

The purpose of this work is to determine consequences of the influence of grazing horses on ground-beetle communities.

2. Materials and methods of the research

The objects of the research were ground-beetles, as the most numerous on species and quantity group of Coleoptera, living on floodplain meadows. To avoid the influence of the seasonal changes in composition and abundance on the results of the research samples were selected every two weeks during the growing season. Ground-beetles were collected by the methods adopted in zoological studies – with the help of soil traps. The degree of environmental similarity of grazed meadows by the ground-beetle complexes was calculated according to [8]:
√c(a+b)∙100Psc

2ab ,

where c is the number of common species; a and b - the number of species in comparable communities; Psc - the amount of the lesser of two indicators of each

species abundance.

The degree of relative biotopical attachment of the species was determined by ratio of the difference between the percentage of species in a given biotope and its percentage in all investigated habitats to the sum of these shares [9].
The degree of species dominance was calculated according to [10].

During the study period 5198 traps/days were processed, 6024 specimens of ground-beetles were determined. On the grazed meadow we used the so-called gentle method of grazing horses. It lied in the facts that in the spring, almost to the end of May horses were not put out on a meadow. These data were like an original starting point of the ground-beetle community. Then horses were grazing only after 22 days later, in the summer at the end of May – mid June (grazing I), when the grass grew back up to 15 cm. The second grazing started after 40 days, and the third one only after 55 days. In the autumn, starting from the end of August, horses did not graze.

3. Results and discussion

Since a fresh grass contains a lot of potassium in the spring (under the snow), it cannot be used for horses. So they were put out on a meadow just at the end of May. From late April to late May the meadow served as a starting point for counting ground-beetles. During this period 35 species of ground-beetles represented 18 genera on the floodplain meadow were found. Among genera Harpalus (6 species) and Bembidion (5 species) were the most numerous on the number of species. In addition, it is established that during the growing season the number of species in grazed plots compared with initial ones did not change - 34-51 species. Only the composition of species changed. So, at the beginning spring-and-summer rare species were present. They disappeared during the subsequent period - Elaphrus cupreus, Broscus cephalotes, Bembidion lampros, Amara spreta, Harpalus anxius, Ophonus nitidulus. All of them were found to be widely distributed on the territory of Belarus, except Ophonus nitidulus, which was found only in northern and central parts of Belarus. Three species (Poecilus cupreus, Bembidion properans and Amara aenea) prevailed here (Table 1). Loricera pilicornis (3,5%) and Harpalus rufipes (1,6%) were subdominants. The rest 30 species belonged to rare ones. The causes of rarity and a local occurrence of certain species of ground-beetles in the involved area have a different basis.

Table 1 The degree of dominance of the dominant species on the meadows after grazing horses

Dominants	Biotopes
	initial area	grazing I	grazing II	grazing III
Poecilus cupreus (L.)	79,0	49,0	10,7	40,6
Bembidion properans (Steph.)	5,2	14,9	5,4	18,4
Amara aenea (Deg.)	4,9	12,0	-	6,5
Loricera pilicornis (F.)	-	5,7	-	-
Harpalus rufipes (Deg.)	-	-	-	5,7
Calathus fuscipes (Gz.)	-	-	-	4,5

Some of them were located on the boundary of its geographic range, while others were local, others lived in specific habitats, locally occurring in the territory. Finally, a number of species is poorly explored and data on their biotopical attachment and geographic range are very fragmentary.

Seven groups, of which field (44,2 %) and forest (23,5 %) species dominated, were selected on their biotopical attachment. It was explained by the proximity of the fields with various cultures and the forests (Table 2). On phenology of development three groups were selected, among which spring-and-summer species dominated, making 82,3 %. In relation to soil humidity five groups were selected. Among them mesophiles (35,3 %) prevailed.

Table 2 The abundance of species on biotopical attachment, phenology of development and relation to soil humidity in biotopes after grazing horses

Groups	Biotopes
	initial area	grazing I	grazing II	grazing III
Abundance of species on biotopical attachment (%)
Field	44,2	37,9	54,0	45,5
Forest	23,5	24,3	26,0	27,3
Meadow-and-field	14,7	10,8	8,0	6,1
Meadow	5,9	5,4	2,0	9,1
Meadow-and-forest	5,9	5,4	4,0	3,0
Everybiont	2,9	2,7	2,0	3,0
Swamp	2,9	5,4	2,0	3,0
Meadow-and-swamp	-	8,1	2,0	3,0
Abundance of species on phenology of development (%)
Spring-and-summer	82,3	76,3	58,8	61,7
Summer-and-autumn	11,8	7,9	5,9	5,9
All-season	5,9	13,2	23,5	26,5
Summer	-	2,6	11,8	5,9
Abundance of species on relation to soil humidity (%)
Mesophiles	35,3	26,3	47,1	44,1
Mesogygrophiles	26,5	23,7	17,6	14,7
Gygrophiles	14,7	36,8	11,8	14,7
Xerophiles	17,6	7,9	9,8	11,8
Mesoxerophiles	5,9	5,3	13,7	14,7

After grazing I the quantity of ground-beetle species did not change (38 species from 17 genera, among which Pterostichus (7 species) and Carabus (5 species) were the most numerous on the number of species, i.e. there was a change of genera by the number of species. Among them rare, spring-and-summer species Pterostichus anthracinus, Pt. minor, Pt. diligens, Pt. aterrimus, Pt. vernalis, from Carabus - C. menetriesi and C. clathratus were found. 17 species, which did not occur on an initial area, appeared. Of these 9 species (Blethisa multipunctata, Pterostichus anthracinus, Pt. minor, Pt. diligens, Pt. aterrimus, Agonum duftschmidi, A. viduum, Amara eurynota, Badister peltatus) were not found more on meadows. They were rare or locally common species. Four species dominated, i.e. conditions improved for species prevailing on the number. This is Poecilus cupreus, Bembidion properans, Amara aenea and Loricera pilicornis. By reducing the number of the first dominant the dominance degree of the other three dominants increased. Loricera pilicornis (a subdominant on an initial area) went into a dominant after grazing I. Poecilus versicolor (2,5 %), Harpalus rufipes (2,2), Pterostichus nigrita (1,9) and Carabus menetriesi (1,8 %) were subdominants. The other 30 species were rare.

8 groups were selected on biotopical attachment, of which field and forest species also dominated. Small amounts of meadow-and-swamp species (8,1 %), which were not on an initial area, appeared. Four groups were selected on phenology of development, among which spring-and-summer species dominated making 76,3 %. Summer species, which were not in the spring, appeared in connection with the onset of summer. 5 groups were selected on relation to soil humidity as well, of which mesophiles (35,3 %) dominated. It was 21 common species between an initial area and grazing I. The degree of environmental similarity among them was quite high and amounted to 62,4 %.

After grazing II in the summer (from June till the end of August) the number of species (51) and genera (21) also did not change. The composition of genera including a large number of species changed. They were Amara (10 species), Harpalus (8) and Carabus (5 species). The rest genera contained from 1 to 4 species. Within the genus Amara rare (80 %), spring-and-summer (70 %), field (70 %) species (A. famelica, A. familiaris, A. tibialis; of the genus Harpalus - H. signaticornis and H. xanthopus winkleri) were found.

22 new species appeared: there were no species on an initial area after grazing I. They belonged mainly to forest species (41 %) preferring mesophilic conditions, extended in all seasons of year (since spring till autumn) or only in the spring and in the summer. Thus two circumstances could play a role. First, feeding horses favorably affected some field, rare species of ground-beetles (Calathus fuscipes, C. ambiguus, melanocephalus, C. halensis, Agonum dolens, Amara plebeja, A. famelica, A. familiaris, ovata, A. similata, A. tibialis, A. bifrons, A. apricaria, Bradycellus caucasicus, Harpalus tardus, Microlestes minutulus), for which better microclimatic conditions were created. Secondly, though forest species (Notiophilus palustris, Carabus hortensis, Epaphius secalis, Pterostichus niger, Pt. melanarius, Calathus melanocephalus, Amara ovata, A. similata, Harpalus smaragdinus) fly badly enough, they use flight for settlement of young beetles, which emerged from a pupa and lost ability to flight in the process of maturing. This leads to a well-known proverb, which may be paraphrased and applied to ground-beetles: the born to run can't fly. Of these 22 species A. tibialis and H. smaragdinus didn't appear more on meadows. The first species preferred fields and consequently was very rare on meadows, and the second one more often occurred in the young light forests.

After grazing II the quantity of dominants decreased to 2 - Poecilus cupreus (10,7 %), Bembidion properans (5,4 %). Hence, conditions for dominants became worse. Loricera pilicornis was a subdominant (1,5 %). The other 48 species were rare.

8 groups, of which field (54 %) and forest (26 %) species also dominated, were selected on biotopical attachment. Meadow-and-swamp species, which were not on an initial area, appeared. 4 groups, among which spring-and-summer species again dominated, were selected on phenology of development, making 58,8 %. With approach of autumn more multiseasonal (23,5 %) species appeared, the quantity of summer-and-autumn species became much less (5,9 %). 5 groups, of which mesophiles also dominated, were selected on relation to soil humidity. More mesoxerophile species appeared in connection with the reduction of rainfall. There were 21 general species between grazing I and grazing II. The degree of environmental similarity among them was high enough making 62,7 %.

After grazing III in the end of August the quantity of species (34) and genera (19) did not change in comparison with ground-beetles after grazing II. The structure of genera containing a considerable quantity of species changed a little. They were Amara (8 species), Harpalus and Calathus (on 3 species). The other genera contained 1-2 species.

10 new species, which weren't on an initial area, appeared after grazing I and grazing II. It was mainly rare species, a half of which was made by field species. The third part of species belonged to multiseasonal ones, and the rest – to spring-and-summer species, late in the development.

After grazing III the quantity of dominants increased to 5 and almost reached an initial level after grazing I, excluding Loricera pilicornis (4,0 %), which became a subdominant. Two species – H. rufipes (5,7 %) and C. fuscipes (4,5 %) – were added to dominants. The quantity of subdominants increased to 4. Hence conditions for ground-beetles improved after grazing III. The other 25 species were rare.

8 groups, of which field (45,5 %) and forest (27,3 %) species dominated, were selected on biotopical attachment. It was explained by the proximity of the fields with various cultures and the forests (see Table 2). 4 groups, among which spring-and-summer species dominated, were selected on phenology of development, making 61,7 %. 5 groups, from which mesophiles dominated (44,1 %), were selected on relation to soil humidity. There were 23 general species between grazing II and grazing III. The degree of environmental similarity among them was low and amounted 37,1 %. Horses did not graze any more as in the late autumn level of nitrates increased in the grass due to an insufficient insolation and rainy weather.

If to spend a comparison of ground-beetle communities after three grazing one could conclude that the sparing mode of grazing horses didn't lead ground- beetle communities to a large reorganization in their structure. The quantity of species remained unchanged throughout all growing season. The structure of species was not changing long time, remained high enough and only by the autumn made the third part of initial forms, due to the fact that many species already finished the development by the autumn. The species of field, forest and everybiont groups were steady enough to grazing horses; their abundance remained at the same level throughout the whole season. Meadow-and-field, meadow-and-forest, meadow, swamp and meadow-and-swamp groups, which number was insignificant, were the most sensitive to grazing. Some groups (meadow and forest) increased their number by the autumn, and others such as meadow-and-field, meadow-and-forest and meadow-and-swamp decreased.

4. Conclusions

Thus, as a result of studying zoocoenotic indicators of ground- beetle communities 83 species living on floodplain meadows were revealed. Of the ecological groups selected on relation to humidity the greatest number of species on floodplain meadows presented mesophiles, and after grazing I, obviously, with rainfall gigrophiles were. On the basis of biotopic distribution we took these species to 8 ecological groups. Field species were characterized by the most number, sometimes their abundance reached 54 %. The majority of ground-beetle species (82,3 %) bred in the spring and in the beginning of summer. Species of multiseasonal phenological group weren't numerous (5,9 % – 26,5 %), and summer and summer-and-autumn groups were random (2,6 % - 11,8 %). It was explained by migration of “nearwater” mesophile species, which made a considerable part in fauna, from a spring high water to adjacent biotopes.

References

[1] I.H. Sharova., V.G. Matveeva, Complexes of ground-beetles of floodplain meadows in the landscape zones of the European part of the USSR: Proceed., (1974) 3-17. (in Russian)

[2] V. F. Antoshchenkov, Influence of a mode of the pasture site use on a ground-beetle complex, in: Fauna and ecology of invertebrates: Proceed., М, (1979). 41-47. (in Russian)

[3] A.I. Averensky, Ground-beetles (Coleoptera, Carabidae) of the valley of average Amga, in: Insects of meadow-and-taiga biocenoses of Yakutia: Proceed., Yakutsk, (1988) 34-42. (in Russian)

[4] V.P. Pristavko, A.M. Tereshkin, A.S. Shlyahtenok, O.R. Aleksandrovich, To knowledge of ground-beetle fauna (Coleoptera, Carabidae) of the Berezinsky Reserve in: Reserves of Belarus. Minsk, (7)(1983) 108-114. (in Russian)

[5] A.S. Shlyahtenok, Fauna of ground-beetles (Coleoptera, Carabidae) on dry meadows of the Berezinsky Biospheric in: Reserve and the influence of hay-mowing and grazing cattle on it, Questions of experimental zool. Minsk, (1983) 119-125. (in Russian)

[6] A.S. Shlyahtenok, Ground-beetles (Coleoptera, Carabidae) of meadow communities as an object of ecological monitoring, in: Fauna and ecology of insects of the Berezinsky Reserve, Proceed., Minsk (1991) 146-169. (in Russian)

[7] V. P. Pristavko, Vital forms of insects as a criterion at the selection of species-indicators for ecological monitoring (on an example of ground-beetles Coleoptera, Carabidae), Entomol. Review, 63(1)(1984) 52-56. (in Russian)

[8] L.Gruia, Un nouvel indice écologique de similarité, Hidrobiologia (RSR), 16 (1980) 19-26. (in Romanian)

[9] Yu.A. Pesenko, Principles and methods of the quantitative analysis in faunistic researches. М.: Nauka (1982) 287 pp. (in Russian)

[10] V.F. Paliy, Methods of studying fauna and phenology of insects, Voronezh, (1970) 189 pp. (in Russian)