Orthopteran fauna of the Hel Peninsula in Poland

Grasshoppers and katydids (Orthoptera) were studied on sand dunes of the Hel Peninsula in northern Poland in 2013. Altogether, 11 species o f grasshoppers and katydids were identified, three o f them can be regarded as elements o f the fauna characteristic for sand dunes. Species diversity and population density was higher in the seaside with sparse vegetation than in the neighboring pine forest. The reported low species richness is comparable to other peninsula covered by sand. Myrmeleotettix maculates was most abundant, particularly by the seaside with low shrubs and Tetrix bipuncata occurred frequently in each habitat, but especially on the forest gaps.

The aim of the study is to know what Orthoptera species occur in the various habitats of the Hel Peninsula.

S t u d y a r e a , m a t e r i a l a n d m e t h o d
The Hel Peninsula is a long and narrow mass of land, extending 36 km east of Władysławowo (near the Tricity -Gdańsk, Gdynia and Sopot) out into the Baltic Sea, with a width varying between 100 m and 3 km.The average annual precipitation and the average precipitation in the vegetation period (May-July) are 528 mm and 156 mm, respectively.July is the wannest month, with a daily average temperature ranging from 16.6 to 17.7°C.The average number of frost days is 89.4 (Wojterski & Bednorz 1982).The vegetation consists of 204 plant species with 155 genera and 50 families.The most numerously represented families are Compositae, Gramineae, Rosaceae, and Leguminosae (Blaszkowski 1994).The dominant tree species is pine (Pinaceae).The various study sites were selected to contain the widest spectrum of habitats of the Hel Peninsula.The orthopterans were collected from four habitats of the Hel Peninsula near the town Hel in various habitats (Fig. 1): 1. Pine forest (F): Dry pine forests (Pinaceae) are dominant vegetation on the Hel Peninsula.The characteristic pines are Pinus nigra Am., P. sylvestris L. and P. mugo Turra.The shrub layer is rather poor.There are local depressions in the forest.The areas with sparse wood as peat-bogs or wet sites are overgrown by Empetrum nigrum L. or Ledum palustre L. The important group consists of mosses (Dicranum sp.. Sphagnum sp., Leucobryum sp.) and lichens (Cladonia sp., Cetraria sp.).

Coastal dune (C):
The dunes covers a narrow strip, from 30 m up to 50 m wide, around the peninsula.The dunes consists of two parts: the white narrow and low, gradually transforming into the grey dune.The width of a typical grey dune is about 20 m.The inland grey dunes are bordered by the dry pine forest or grasslands.The flower vegetation cover and the number of plant species increase with distance from the sea -from white dune to grey dune.The present herb layer contains species winch belong to the families Asteraceae, Brassicaceae, Caryophyllaceae, Cyperaceae, Fabaceae, Lamiaceae, Poaceae (e.g.Acinos a n 'ensis (Lam.)Dandy, Arenaria serpyllifolia L., Artemisia campestris L., Berteroa incana (L.) DC.Carex arenaria L., Corynephorus canescens (L.) P. Beauv., Lathyrus maritimus L., Trifolium ar\!ense L.
3. Grassland (G): Dry meadow with an area of 300 square meters in the middle of the pine forest.The vegetation is dominated by the grasses from the Poaceae and Cyperaceae families and contains the herbs from the families Boraginaceae, Brassicaceae, Crassulaceae, Solanaceae, Urticaceae (e.g.Corynephorus canescens; Berteroa incana, Echium vulgare L., Hyoscyamus niger L., Sedum acre L., IJrtica dioica L.).

Lawn (L):
The urban area includes ruderal herbaceous vegetation between the buildings, with dominant grasses of Cyperaceae and Poaceae.
The material was gathered every day from 15th June to 28th June 2013.Orthopterans were primarily collected from herbal and partially shrub vegetation by sweeping (min.50 sweeps with standard sweep net of 38 cm diameter).Daily time of collection was three hours at each plot.Sample size was dependent on habitat and was 3 individuals on average in 10 sweeps.
The orthopterans (adults) were identified directly in the field, but nymphs were fixed using 70% ethanol and determined in the laboratory using identification keys (Bazyluk 1956, Kocarek et al. 2013).The nomenclature of Orthopera insects is used according to Kocarek et al. (2005), and of plants according to Kubat et al. (2002).In total 126 adults and 42 nymphs of Orthoptera were collected.Eleven species of katydids, grasshoppers and groundhoppers were recorded in the Hel Peninsula (Table 1).This is less than 10% of the species known in Poland.Similar habitats in the coastal dunes (in Belgium, Denmark, Latvia) had 10-23 species (Decleer & Devriese 1992, Folger & Handelmann 1999, Spungis 2007).Range of the most of the recorded species is limited to the Eurosiberian or European region and corresponds to dry grasslands or sandbanks.The species richness differs between the study habitats.The highest number of species was found on the coastal dunes (Table 1).Tetrix bipunctata, Myrmeleotettix maculatus and Chorthippus brimneus were the species with the biggest number of individuals cought.In dry habitats Myrmeleotettix maculatus and Chorthippus brunneus are frequently found (Holst 1986).The groundhopper Tetrix bipunctata is the specific xerothermic species and it was found in all sites of the Hel Peninsula.T. bipunctata inhabits dry short grasslands with partly open soil (Baur et al. 2006).In addition, it can also be present on relatively dry, nutrient-poor forest clearings with sunny, open and mossy areas.This species has a specific life cycle -the individuals hibernate as adults and can be found all the year round.It is observed to be most common in autumn and spring (Baur et al. 2006, Kocarek et al. 2013).Usually, in the early summer, more nymphs than adults are observed but we recorded only adult individuals.
The thermo-and xerophilic species Myrmeleotettix maculatus is one of the smallest European Acrididae.It especially colonizes sand grasslands, dry moorland with open peat spots or stony pastures in the mountains (Detzel 1998).In dry sandy habitats it can reach high densities (Ingrisch & Kohler 1998) and can be a dominant Orthoptera species (Schirmel et al. 2010).Adults are present from early May and can still be observed in early October (Kocarek et al. 2013).
Chorthippus brunneus is a widespread species, but prefers somewhat drier habitats.The habitats with high abundance of the species are often dry and sunny, often woodland clearings or edges and sometimes rocky areas.Furthemore, Ch. brunneus is observed also in nutrient-poor grasslands, on dry agricultural meadows, on embankments and roadsides, in ruderal localities and in gardens but it often occurs only in low density (Ingrisch & Kohler 1998, Bazyluk & Liana 2000, Kocarek et al. 2013).In Poland it is widespread (Bazyluk & Liana 2000).
The pine forest is dominating in the Hel Peninsula and the typical Orthoptera species for such habitat Chorthippus vagans (Eversmann, 1848) was also found there.This grasshopper species inhabits xerothermous areas as sandy pine forests, rocky slopes, dry grasslands and similar areas, usually close to forest habitats (Kocarek et al. 2013).In Poland it is present in 14 regions from the Baltic Coast to the Pieniny Mts.(Bazyluk & Liana 2000).The pine forest is sparse in place sand and allows the xerothermic species to survive (Holuśa 2000).

No
Species The most diverse habitat was the seaside with the various sites, from the bare soil to shrub vegetation (as Rosaceae).It corresponds to several Orthoptera species.Tettigonia viridissima Linnaeus, 1758 inhabits open areas of all types (fields, grasslands) as well as hedgerows, clear cuttings, parks or woodland edges.It prefers warm and rather dry lowland habitats.The distribution extends across most of Europe and temperate Asia (Holst 1986) and is not characteristic for dunes.The katydid Platycleis albopunctata has been recorded from the Hel Peninsula by previous authors (Brischke 1888, La Baume 1920, Bazyluk 1954).It is a subatlantic species, it occurs in all regions of Poland with exception of the Carpathian Mountains (Bazyluk & Liana 2000).This species colonizes rich grasslands or sandy areas and bare slopes.
Pholidoptera griseoaptera occurred in the Hel Peninsula only on edges of grasslands near the pine forest.The individuals moved to the taller vegetation, such as shrubs or herbs (frequently on the Urticaceae).It is one of the most widespread and common bush cricket particularly in forest area and it occurs throughout much of Europe (Maas et al. 2002).Other vegetation types such as meso-and xerothermic grasslands and reed beds (Samietz 1995) may serve as additional feeding habitats.It is abundant in Poland (Bazyluk & Liana 2000).
The blue-winged grasshopper Oedipoda caerulescens is a Palearctic species and inhabits sandy grasslands, rocky slopes or fine-earth rich steppe-like heathland (Appelt & Poethke 1997) or it lives on railway corridors and sand pits.The individuals occurred often in the coastal dune and seldom in the lawn in the Hel Peninsula.The same pattern as Oedipoda caerulescens showed the grasshopper Sphingonotus caerulans.It is known as inhabitant of sandy grasslands or inland dunes (...).
In the extensive lawn of the Hel Peninsula occurred also Chorthippus apricarius and Ch.mollis.Ch. apricarius requires grasslands and at least small gappy areas with open soil.Ch. mollis inhabits warm and dry, nutrient-poor grasslands and sandy grasslands.This species is endangered by the quantitative and qualitative decline of suitable grasslands due to the wellhttp://rcin.org.plknown factors eutrophication, agricultural intensification and overbuilding (Kuijken et al. 2003).
The sandy Hel Peninsula is inhabited by species of Orthoptera which tolerate the specific conditions.These are mainly psammophilic, xerophilous or pioneer organisms.The author is grateful to Dr. Petr Kocarek (CZE) for help in the identification of nymphs (Orthoptera).

Figure 1 .
Figure 1.Map o f Hel Peninsula and habitat sampled for Orthoptera.
R e s u l t s a n d d i s c u s s io n A c k n o w l e d g e m e n t s This research was supported by an Institutional Research Support grant from the University of Ostrava (reg.no.SGS21/PfF/2013, SGS24/PfF/2014).