URBAN POPULATION OF THE GROUND BEETLE CARABUS 
VARIOLOSUS NODULOSUS (COLEOPTERA: CARABIDAE) 
IN LJUBLJANA CITY (CENTRAL SLOVENIA)
Al Vrezec1,2, Irena Bertoncelj3, Andrej KAplA1, Špela AmBrožIč ergAVer1
1 nacionalni inštitut za biologijo, Večna pot 111, SI-1000 ljubljana, Slovenija 
2 prirodoslovni muzej Slovenije, prešernova 20, SI-1000 ljubljana, Slovenija
3 Kmetijski inštitut Slovenije, Hacquetova ulica 17, SI-1000 ljubljana, Slovenija
e-mail: al.vrezec@nib.si, irena.bertoncelj@kis.si, 
andrej.kapla@nib.si, spela.ambrozicergaver@nib.si
Abstract – A population of the endangered ground beetle Carabus variolosus
nodulosus creutzer, 1799 was discovered in landscape park tivoli, rožnik and
Šišenski hrib in the city center of ljubljana. In the park area we recorded 12,275
meters of flowing water. In 2012 and 2014, we confirmed the species at 24 out of 48
sampling sites (50%). the estimated minimal number of adult beetles in 2014 ranged
from 2295 to 5715. Based on the data collected, we zoned the area with the highest
densities. guidelines for the management of the area are also given in order to
maintain or even improve the status of the ground beetle population in ljubljana.
ljubljana holds the only urban population of the species known so far, which might
represent a unique evolutionary significant unit, although its share in the total
population in Slovenia is estimated at only 0.02%.
KeywordS: city park, urban environment, natura 2000, zonation, riparian habitat
Izvleček – UrBAnA popUlAcIjA močVIrSKegA KreŠIčA CARABUS
VARIOLOSUS NODULOSUS (coleopterA: cArABIdAe) V ljUBljAnI
V Krajinskem parku tivoli, rožnik in Šišenski hrib v mestnem središču
ljubljane je bila odkrita populacija ogroženega močvirskega krešiča Carabus
variolosus nodulosus creutzer, 1799. na območju parka smo popisali 12.275 metrov
tekočih voda. V letih 2012 in 2014 smo močvirskega krešiča potrdili na 24 točkah
od 48 vzorčnih mest (50 %). ocenjeno minimalno število odraslih hroščev v letu
2014 je bilo med 2295 in 5715. glede na zbrane podatke smo naredili conacijo
območja z največjimi gostotami. podane so tudi smernice za gospodarjenje z
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ACTA ENTOMOLOGICA SLOVENICA
LJUBLJANA, DECEMBER 2021     Vol. 29, øt. 2: 133–147
območjem, da bi ohranili ali celo izboljšali stanje populacije močvirskega krešiča v
ljubljani, ki je do sedaj edina znana urbana populacija vrste in morda predstavlja
celo edinstveno evolucijsko pomembno enoto, čeprav šteje po oceni le 0,02 %
celotne populacije v Sloveniji. 
KljUčne BeSede: mestni park, urbano okolje, natura 2000, conacija, mokrotni habi-
tat
Introduction
green spaces in urban environments have a positive impact on the quality of life
of residents (Adler & tanner 2013), but at the same time, from the point of view of
biodiversity conservation, they are special habitats due to a different type of manage-
ment, which can have a high conservation value. However, it is important to note that
larger patches of green areas (> 50 ha), habitat corridors and suitable management
are needed to preserve area-sensitive species within urban areas (Beninde et al. 2015).
In the city of ljubljana, one of the most important green islands is the landscape
park tivoli, rožnik and Šišenski hrib. the long-term vision of the city of ljubljana
in environmental protection program for the city of ljubljana envisages sustainable
growth and continuous improvement of the quality of life through the constant pursuit
of a clean, safe and friendly environment for all people and the preservation and cre-
ation of new green spaces with unique biodiversity (jazbinšek Seršen et al. 2014).
the landscape park tivoli, rožnik and Šišenski hrib, located near the city center, is
visited by more than 1,700,000 people per year (Smrekar et al. 2011) and is a key
area for the implementation of this vision.
Surveys of the beetle fauna in the areas of landscape park tivoli, rožnik and
Šišenski hrib have confirmed the presence of some species listed in the european
Habitats directive (council directive 92/43/eec): Carabus variolosus, Lucanus
cervus and Osmoderma eremita (Vrezec et al. 2013), while only historical data are
known for Cerambyx cerdo, Rosalia alpina and Morimus funereus (Brelih et al.
2006).
In the present study, we investigated the distribution and abundance of the popu-
lation of Carabus variolosus in the area of the landscape park tivoli, rožnik and
Šišenski hrib. In Slovenia and ljubljana, the subspecies Carabus variolosus nodulosus
creutzer, 1799 lives, which according to some authors even has species status (turin
et al. 2003), while the genetic structure of populations in Slovenia is even more com-
plex, as shown by a recent molecular study (mossakowski et al. 2020). this is
probably a consequence of the extremely low dispersal of the species with low genetic
heterozygosity of populations and high diversification among populations as a whole
(matern et al. 2009). this means that most populations of Carabus variolosus are
isolated, demographically independent, and even evolve independently. therefore,
isolated and viable populations of the species are particularly worthy of protection
due to their unique genetic structure (matern et al. 2009), which may even function
as evolutionary significant units.
Acta entomologica slovenica, 29 (2), 2021
134
A. Vrezec, I. Bertoncelj, A. Kapla, Ø. Ambroæiœ Ergaver: Urban population of the ground beetle Carabus variolosus nodulosus
135
the ground beetle Carabus variolosus inhabits very wet and swampy banks of
forest streams, which are usually covered with stands of swampy deciduous forests,
especially black alder (Alnus glutionosa), Equiseto-Fraxinetum, Carici-Fraxinetum
and forest stands of beech (Fagus sylvatica) and hornbeam (Carpinus betulus)
(drovenik & pirnat 2003, müller-Kroehling 2006, Vrezec et al. 2007). Adult beetles
live for two to three years, have a low dispersal power and live in relatively small
populations limited to suitable habitat (matern et al. 2007a, 2009). Because the beetle
is strongly tied to wet environments, its reproduction is limited to very moist habitats,
increasing its sensitivity to encroachment into swampy and shaded environments of
forest streams. the species is also affected by habitat fragmentation, which breaks
links between isolated subpopulations (müller-Kroehling 2006). In Slovenia, this
species is still widespread, but according to the results of the population monitoring
at selected sample sites between 2007–2020, it is locally declining (Vrezec et al.
2020).
the aim of the present study was to study the only known urban population of
Carabus variolosus and to give guidelines for improvement of the management of
the area for the conservation of the species in the landscape park tivoli, rožnik and
Šišenski hrib in ljubljana city.
Material and Methods
Study area
the landscape park tivoli, rožnik and Šišenski hrib is located in the center of the
city of ljubljana and covers an area of 459 ha, including the city park tivoli and the
rožnik and Šišenski hrib park forests. the area was declared a landscape park by
decree in 1984, both for natural and cultural aspects. within the landscape park there
are other, special protected areas: the nature reserves mali rožnik (Figure 1) and
mostec, a natural monument in the area below turn, a horticultural monument city
park tivoli and several natural values and cultural heritage sites (Smrekar et al. 2011).
the largest central part of the landscape park (288 ha) is a varied forest area with
five peaks (Šišenski hrib, rožnik, cankarjev vrh, tivolski vrh and debeli hrib).
Forest covers 341 ha or 74% of the area (Smrekar et al. 2011), with the main forest
communities being acidophilous Pineto-Vaccinetum austroalpinum, Alnetum
glutinosae and Querceto-Castanetum (Kermavnar 2015). the area was never
completely deforested in the past, although at least in the 15th century part of the area
was covered with vineyards (Smrekar et al. 2011). the forests are covering the major
part of the area at least from 18th century on, although it seems that this forest
fragment is isolated from the nearby continuous forests at least for 300 years (Figure
2). As late as the end of the 19th century, the forests of the park were inhabited by
true forest bird specialists such as the capercaillie (Tetrao urogallus) and the Ural
owl (Strix uralensis) (Schulz 1895), indicating the presence of primeval forest
stands in the park. Both species have disappeared from the park's forests to date
(tome et al. 2013), but forest cover has remained unchanged for at least the last 100
years (Smrekar et al. 2011). In the ljubljana urban forest, the economic use of timber
is low, and social and regulatory functions, including biodiversity conservation, are
more important (Smrekar et al. 2011).
In the eastern part of the park there is the 43 ha large city park tivoli, which is an
example of designed nature and was declared as city park already in 1814 (Smrekar
et al. 2011). on the western side of Šišenski hrib is the only large flat area within
landscape park. lake Koseze is located there and south of it are the only large non-
forested areas of the park. the landscape park is completely surrounded by built-up
areas from three directions (north, south and east). only on the western side is the
area connected to the wider hinterland of the hills of polhov gradec, but this ecological
corridor is interrupted by the western part of the ljubljana bypass (Smrekar et al.
2011).
larger watercourses in the area are the mostec stream, which flows into lake
Koseze, and pržanec and glinščica streams on the edge of the park (Figure 3). Higher
parts of the area consist of mechanically less resistant permocarbonate shales, sand-
stones and conglomerates, so smaller streams have carved deep and steep ravines.
due to the small catchment areas, rožnik watercourses usually dry up during the
summer months (Smrekar et al. 2011). during sampling of fish and crayfish in
mostec, glinščica, pržanec, lake Koseze and tivoli ponds, Bertok and podgornik
(2004) found that only mostec stream is preserved in a more or less natural form,
while the other water bodies are anthropogenically modified and impoverished.
Acta entomologica slovenica, 29 (2), 2021
136
Figure 1: example of a
swampy bank of a forest stream
in the area of the landscape park
tivoli, rožnik and Šišenski hrib
in the area of mali rožnik as a
habitat for Carabus variolosus
(photo: Irena Bertoncelj).
Slika 1: primer zamočvirjene
brežine gozdnega potoka na ob-
močju Krajinskega parka tivoli,
rožnik in Šišenski hrib v predelu
malega rožnika kot življenj -
skega prostora močvirskega
krešiča Carabus variolosus
(Foto: Irena Bertoncelj).
A. Vrezec, I. Bertoncelj, A. Kapla, Ø. Ambroæiœ Ergaver: Urban population of the ground beetle Carabus variolosus nodulosus
137
Figure 2: comparison of maps of the area of the landscape park tivoli, rožnik
and Šišenski hrib and nearby surrounding from years 1763 (above; josephinische lan-
desaufnahme 1763–1787 für das gebiet der republik Slowenien) and 2015 (below). 
Slika 2: primerjava kart območja Krajinskega parka tivoli, rožnik and Šišenski
hrib in bližnje okolice med letoma 1763 (zgoraj; josephinische landesaufnahme 1763–
1787 für das gebiet der republik Slowenien) in 2015 (spodaj). 
As part of this research, we sampled the central forested part of the landscape
park between tivoli and Večna pot.
Field sampling
we mapped all streams, their tributaries, springs and standing waters. during the
fieldwork we used gpS to record the route and waypoints, which were processed
using ArcgIS (eSrI). this allowed us to estimate the size of Carabus variolosus
habitat in the area.
Beetles were sampled in 2012 and 2014 during the spring peak of adult activity
between may and june. we used pitfall traps (diameter of 10 cm) placed directly ad-
jacent to streams, not more than 0.5 m from the water line, and left open for seven
days, when they were collected (Vrezec et al. 2009). the traps contained a smaller
amount of wine vinegar as bait and a number of structures (pebbles, pieces of bark,
and twigs) to prevent drowning of captured animals. Five traps were set at each site
for a total distance of 25 meters along the stream. At 40 sampling sites 200 pitfall
traps were set in total. Fieldwork was conducted under a permit from Slovenian en-
vironment Agency no. 35601-75/2012-8.
Data analysis
Systematic sampling at a large number of sampling sites allowed us to calculate
relative abundances of beetles (Krebs 1999). Systematically collected data and calcu-
lated relative abundances are particularly important for quantitative assessment of
the importance of the local population at the national level, as they show how important
the area is compared to other areas sampled using the same method (Vrezec & Kapla
2007). relative abundances do not represent the true absolute values of population
densities, but they allow effective comparisons between areas, i.e. they indicate the
population core areas with higher densities (Sutherland 2000, Vrezec et al. 2005,
2012). For sampling with traps, the sampling unit was the trapping night, i.e. the
catch of 10 traps in one night. the relative abundance (rA) was therefore calculated
as follows:
rA = no. individuals × 10 / [no. traps × no. nights]
to calculate the relative abundance, we only considered the data from the sites where
the species was found. For Carabus variolosus, reference tables of relative abundances
were prepared, which allowed us to determine the rank of local abundances according
to the situation in Slovenia. these reference values include data collected during the
national population monitoring of the species between 2007 and 2012 (table 1). the
mean value of relative abundance in the area of landscape park tivoli, rožnik and
Šišenski hrib can thus be classified into one of three classes: low density (mIn - values
between the minimum and the first quartile (Q1) of all known relative abundances in
Slovenia), medium density (med - values between the first (Q1) and the third quartile
(Q3) of all known relative abundances in Slovenia) and high density (mAX - values
above the third quartile (Q3) of all known relative abundances in Slovenia).
Acta entomologica slovenica, 29 (2), 2021
138
Using data collected in 2014 (40 sampling sites), we estimated the minimum
number of active adults of Carabus variolosus based on the total number of caught in-
dividuals. the sampling was conducted in one catching session only lasting 7 days
and without repeated recaptures. therefore only minimal possible population estimate
can be given. the species is mostly active up to 2 meters from the streambed (Bric
2011). At each site, we covered 25 meters of the stream with five traps, giving us 100
m2 of inspected habitat for the species. Based on the number of beetles captured in
seven days, we calculated the minimum absolute density (number of specimens / m2).
we calculated the average absolute density at all 40 sampling sites, which, according
to systematic sampling, should reflect the average density of the species along water-
courses in the area in a strip of 2 meters on each side of the stream. Using the
measured length of watercourses in the area of landscape park, we estimated the
total habitat of the species in which we estimated the minimum number of active
adult beetles at the time of sampling. Abundance was expressed in the interval calcu-
lated based on average density, and the upper limit was expressed as average density
with standard deviation added.
the area of landscape park was zoned according to habitat availability based on
all data collected on the occurrence of Carabus variolosus. zonation was done using
a conservative approach and respecting the precautionary principle. the impact zone
was estimated to be 25 m on either side of the stream bed. this zone includes a
narrow area of activity for the species along the stream where the majority of the
population resides (matern et al. 2007b, Bric 2011), and a broader area of impact im-
portant for shading the streambed and wet banks (matern et al. 2007b).
the data were processed in mS excel, and the map views with Arcgis 9.3
Results
Mapping of watercourses in the Landscape Park Tivoli, Rožnik and Šišenski hrib
during the mapping of watercourses, 12,275 meters of flowing waters, 10 standing
waters and six springs were recorded in the area of landscape park tivoli, rožnik
A. Vrezec, I. Bertoncelj, A. Kapla, Ø. Ambroæiœ Ergaver: Urban population of the ground beetle Carabus variolosus nodulosus
139
Table 1: reference values of relative abundances (rA [no. of individuals / 10
trap nights]) of ground beetle species Carabus variolosus nodulosus in Slovenia de-
termined between 2007 and 2012 (n = 205 locations with confirmed presence of the
species; Vrezec & Kapla 2007, Vrezec et al. 2012)
Tabela 1: referenčne vrednosti relativnih gostot (rA [št. osebkov / 10 lovnih
noči]) močvirskega krešiča Carabus variolosus nodulosus v Sloveniji ugotovljene
med letoma 2007 in 2012 (n = 205 lokacij s potrjeno prisotnostjo vrste; Vrezec in
Kapla 2007, Vrezec s sod. 2012)
Statistical value RA 
First quartile (Q1) 0.67
median (med) 1.33
third quartile (Q3) 2.57
maximum (mAX) 27.67
and Šišenski hrib (Figure 3). the longest and most branched is the system of forest
streams that flow into the stream in mostec. the other streams are mostly very short
and become channelized once they reach the forest edge. we only mapped the streams
during the period of higher water levels, so we did not record which of the streams
dried up during the hot summer months.
In the area of Šiška on the pod hribom road, where the hilly part steeply turns
into a plain, we recorded six springs, all of which are canalized. of the 10 standing
waters, six are in the area of ljubljana zoo. the largest standing water is lake
Koseze, which has a naturally constructed bank. In its immediate vicinity, on the
southern edge, there is also a small marshy water body. tivoli pond, which was
emptied and restored in 2011, has a paved bank. As a standing water body, we also
studied and sampled mali rožnik, the area of natural value of national importance.
Survey of Carabus variolosus
In 2012, we confirmed Carabus variolosus at four of eight sampling sites (50%)
and in 2014 at 20 of 40 sampling sites (50%) (Figure 4). during systematic sampling
Acta entomologica slovenica, 29 (2), 2021
140
Figure 3: mapped network of watercourses in the area of the landscape park
tivoli, rožnik and Šišenski hrib – springs (points), running (lines) and standing
waters (polygons).
Slika 3: Skartirana mreža vodotokov na območju Krajinskega parka tivoli, rožnik
in Šišenski hrib – izviri (točke), tekoče (linije) ter stoječe vode (poligoni).
in 2014, we captured 186 specimens in 1,400 trapping nights, of which 97 were
females and 89 males (the ratio of females to males was 1.1:1.0). 
In 2014, we calculated the relative abundance of captured beetles for each sample
site where the presence of the species was confirmed. the median relative abundance
of Carabus variolosus in landscape park tivoli, rožnik and Šišenski hrib was 2.57
(mIn -mAX: 0.29 - 7.71), which is slightly higher than the median relative abundance
for Slovenia. However, at 45% of the sample sites we confirmed the abundances be-
longing to the upper quartile of the abundances found so far in Slovenia. the highest
abundances of Carabus variolosus were found in the upper reaches of the tributaries
of the streams in mostec and in mali rožnik. the species was not found in the
streams in the eastern part of landscape park (Figure 4).
A. Vrezec, I. Bertoncelj, A. Kapla, Ø. Ambroæiœ Ergaver: Urban population of the ground beetle Carabus variolosus nodulosus
141
Figure 4: the presence and relative abundance of Carabus variolosus nodulosus
in the area of the landscape park tivoli, rožnik and Šišenski hrib was established in
2012 and 2014, and the display also includes random finds. the results of sampling
in 2012 and random finds are shown only by the presence or absence of the species.
relative abundances are shown only for systematic sampling performed in 2014.
Slika 4: prisotnost ter relativna gostota močvirskega krešiča Carabus variolosus
nodulosus na območju Krajinskega parka tivoli, rožnik in Šišenski hrib ugotovljena
v letih 2012 in 2014, prikaz pa vključuje tudi naključne najdbe. rezultati vzorčenja
v 2012 ter naključne najdbe so prikazani le s prisotnostjo oziroma odsotnostjo vrste.
relativne gostote so prikazane samo za sistematično vzorčenje izvedeno v letu 2014.
the narrower habitat of the species is a 4-meter strip along streams covering an
area of 49,100 m2 in landscape park tivoli, rožnik and Šišenski hrib. Based on sys-
tematic sampling, we estimated that in a 4-meter strip along streams the minimal
density of active adult beetles in 2014 was at least 4.67 ± 6.97 individuals / 100 m2.
this means that the population of the species in 2014 in the area of landscape park
tivoli, rožnik and Šišenski hrib numbered at least 2295 to 5715 adult beetles.
Zonation of the area for Carabus variolosus conservation
Based on all collected data and taking into account the precautionary principle,
we zoned the area landscape park tivoli, rožnik and Šišenski hrib according to the
availability of Carabus variolosus habitat (Figure 5). In zoning, we took into account
all collected data on the presence or absence of the species. the habitat zone of
Carabus variolosus in landscape park consists of all streams and their tributaries
where the presence of this species has been confirmed and where the presence of this
species is most likely according to the data collected. the watercourses in the western
part of the park proved to be important for the conservation of Carabus variolosus
(Figure 5).
Acta entomologica slovenica, 29 (2), 2021
142
Figure 5: zonation of the landscape park tivoli, rožnik and Šišenski hrib area
in according to the habitat of the ground beetle Carabus variolosus (red areas).
Slika 5: conacija območja Krajinskega parka tivoli, rožnik in Šišenski hrib
glede na življenjski prostor močvirskega krešiča Carabus variolosus (rdeče površine).
Discussion
the importance of the Carabus variolosus population in landscape park tivoli,
rožnik and Šišenski hrib is relatively low at the national level, as the park population
has been estimated at only 0.02% of the total Slovenian population of this species
(Vrezec et al. 2012), or at least 5,000 active adult beetles. this estimation should be
improved in future studies using more accurate capture-mark-recapture method
(matern et al. 2007a). nevertheless, up to our knowledge this is the only known
urban population of the species so far, even at the european level, where it is con-
sidered a rare stenotopic species of smaller, mostly montane streams, marshes and
swamps (turin et al. 2003). the population in europe appears to be severely depleted,
as the species is considered extinct in Belgium, France, Italy, Switzerland and
northern germany, while it is considered critically endangered in the rest of its
range in germany, Austria and the Balkans (turin et al. 2003). In this respect, the
urban population in ljubljana is a unique exception that requires stricter protection.
due to previous deforestation and recent heavy urbanisation it is now an isolated
population remnant for at least 300 years (Figure 1). However, historical isolation
processes are still unexplored. In respect to the species genetic differentiation (matern
et al. 2009) the described unique urban population might hold specific genetic struc-
ture as an evolutionary significat unit, and strict conservation measures are needed
to prevent its extinction. Further genetic study of this unique urban population are
highly needed.
In this study, streams and their headwaters in the area of mostec, mali rožnik,
around ljubljana zoo and below cankarjev vrh proved to be particularly important
for the species. Flowing water is the key, but not standing water. the latter is probably
also the result of major encroachments on standing water in this area. the area of city
park tivoli is less important for Carabus variolosus.
In the urban forest of landscape park tivoli, rožnik and Šišenski hrib ecological
and social functions (recreation, education) are emphasized for the benefit of citizens.
the importance of the wood-producing function of the forest is low, but present
(Smre kar et al. 2011). In order to preserve the biodiversity of the park, logging should
be limited to the most urgent protection and remediation measures. this is especially
true for cutting trees along forest streams, where increased thinning can cause accel-
erated drying of streams and marshy portions along them, negatively affecting the
population of Carabus variolosus. clearcuts along streams are particularly unfavor-
able.
For the long-term conservation of the natural network of watercourses with its as-
sociated biodiversity, which is unique to urban forests, we propose the following
management guidelines that will help conserve the Carabus variolosus population
(adapted according to matern et al. (2007b) proposal):
(1) A prohibition on logging and other forestry activities in the immediate vicinity
of forest streams defined by a 50 m impact zone from the streams;
(2) A ban on regulation and rapid drainage of streams in the area of landscape
park tivoli, rožnik and Šišenski hrib, which would lead to drying of the riparian
A. Vrezec, I. Bertoncelj, A. Kapla, Ø. Ambroæiœ Ergaver: Urban population of the ground beetle Carabus variolosus nodulosus
143
zone, as well as regulation of banks within zones that could significantly affect or
even destroy Carabus variolosus habitat;
(3) maintaining the natural dynamics of the watercourse with occasional flooding,
which maintains soil moisture with increased bank sedimentation, which also contributes
to reduced overgrowth of the bank with scrub (the measure also increases the retention
time of water in the park area, which is important due to the reduction in water
overflow during heavy rains, which is critical to limiting erosion and flooding (Adler
& tanner 2013), as the park is surrounded by predominantly urbanized areas);
(4) Avoiding the planting of non-native conifers, especially norway spruce, in
close proximity to the streams, as these contribute significantly to the acidification of
the substrate and thus the water;
(5) leaving fallen logs, especially of softwood species, along streams that serve
as overwintering structures for the beetle.
In the urban environment, the potential for introduction of non-native species is
greater than elsewhere and increases significantly with distance from stores selling
such live animals (chucholl 2014), which is particularly evident for aquatic species.
the likelihood of live animals being released increases with their accessibility to hu-
mans and with the population density of people in a given area, which is highest in an
urban environment. In the case of the watercourses in the landscape park tivoli,
rožnik and Šišenski hrib, as well as in the wider area of ljubljana, the risk of intro-
duction of non-native aquatic species is particularly high. From the perspective of
streams, which are the habitat of Carabus variolosus, it is important to highlight the
risk of introduction of non-native crayfish species, which have been shown to have
impacts on hydrology and biodiversity (Souty-grosset et al. 2006; Vrezec & Brancelj
2012). Impacts on biodiversity are reflected in both disease transmission and extinction
of some aquatic species due to increased predation, such as hygrophilous beetles
(casale & Busato 2008). Among the latter, the red Swamp crayfish Procambarus
clarkii is particularly dangerous, for which we also record cases of releases into the
environment in Slovenia (govedič 2018). no alien crayfish species have yet been
recorded in the wider ljubljana area, but due to the free availability of live crayfish
in stores in ljubljana (Vrezec & Brancelj 2012), the risk of introduction is high. Suc-
cessful introduction of predatory alien species may destroy the only known urban
population of Carabus variolosus, despite strict conservation measures to protect its
habitat.
the results of this and some previous studies on the biodiversity of the landscape
park tivoli, rožnik and Šišenski hrib (e.g. mihelič 2005; tome et al. 2013; Vrezec
et al. 2013) show quite high diversity. this state of biodiversity is unique in european
urban forests, so this is content that should be better exploited in ljubljana in terms
of promotion and education. due to the large number of visitors on the one hand and
the interesting biodiversity on the other hand, landscape park tivoli, rožnik and
Šišenski hrib allow a large part of the city population to have direct contact with the
specifics of the natura 2000 network. As such, it can serve both as an educational
and tourist facility and as an example of good practice in the conservation of endan-
gered species at the european level.
Acta entomologica slovenica, 29 (2), 2021
144
Aknowledgements
presented study was funded by the city of ljubljana (representative marjana
jankovič). we would also like to thank to dr. martina jaklič for her help with the
field work. we would like to thank to the anonymous reviewers for very helpful
comments and additions.
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Received / Prejeto: 21. 9. 2021
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