The diversity of amphibian species in water bodies of Kozienice Forest

FRAGMENTA FAUNISTICA 49 (2): 153 163, 2006 PL ISSN 0015-9301 MUSEUM AND INSTITUTE OF ZOOLOGY PAS The diversity of amphibian species in water bodies of Kozienice Forest Michał J. DĄBROWSKI* and Witold STRUŻYŃSKI** *Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, 00-679 Warsaw, Poland; e-mail: michal@miiz.waw.pl **Department of Zoology, Warsaw Agricultural University, Ciszewskiego 8, 02-787 Warsaw, Poland; e-mail: wstruzynski@tlen.pl Abstract: In the years 2003 2005, the diversity of amphibian species in Kozienice Forest was analyzed. Thirteen species of amphibians were found in 91 different water habitats. The most common were Rana esculenta, R. temporaria and Bufo bufo, the rarest Triturus vulgaris, B. viridis and T. cristatus. We confirmed the presence of all species which had been found in this area in the beginning of 70s. Beside the check-list of amphibians of this area, we recognized their preferences for several important features of the studied water habitats. The most obvious, was the tendency of green frogs, for inhabiting large and stable water bodies. The differences in species diversity and relative abundance between Kozienice Landscape Park and other protected forests were discussed. Key words: amphibians, distribution, Kozienice Landscape Park, habitat preferences, species richness INTRODUCTION Sudden extinctions of amphibian species and decline of their local populations have been observed for the last 20 30 years. Since early1990s, many studies have focused on global patterns of amphibian declines (Barinaga 1990, Wake 1991, Pechmann & Wilbur 1994). It is suspected that several interacting causes rather than one common reason have led amphibian populations and species to extinction. Six major hypotheses existing in the literature may be sorted into two categories. The first category indicates factors that directly interact with amphibian population, like land use changes, commercial over-exploitation, emerging infectious diseases and alien species. To the second category belong factors which indirectly affect amphibians: chemical pollutions, increased UV radiation and global climate change (Collins & Storfer 2003). Published papers have reported declining populations and extinction of amphibian species everywhere: in South and North America (Stebbins & Cohen 1995, Pounds et al. 1997, Lips 1998, 1999), in Australia (Laurance et al. 1996) and in Europe (Blab & Vogel 1999). It is well documented, particularly for Western Europe, that once common species have now become rare and live in isolated populations (Honegger 1978, Terhivuo 1981, Blab et al. 1984, Thielcke et al. 1991). In Poland, the dynamics of amphibian declines have not been so well documented as in West European countries. Nevertheless, in some areas this decline was well documented (Juszczyk 1987, Berger 2000, Rafiński & Tabasz 2001, Głowaciński & Rafiński 2003). For example, in Niepołomnice Forest, during twenty years, in the 70s and 80s of twentieth century, the number of amphibians was reduced by 90%, from 2000 to 150 300 individuals per one hectare (Głowaciński & Witkowski 1970, Witkowski 1978, Głowaciński 2003). Similarly, in agricultural landscape of Wielkopolska (Western Poland) during about ten years in the late 60s and early 70s the number of amphibians was reduced from 300 to dozen or so individuals per one hectare (Berger 1987, Rybacki & Berger 1997). Also in protected natural areas, population

154 M. J. Dąbrowski and W. Strużyński declines and species extinctions have been observed for the last fifteen years, for example in Ojców National Park (Szyndlar 1994, Rafiński & Tabasz 2001). Nowadays, the most urgent issue is to recognize the state of amphibian population in other areas and collect new information from areas researched in previous decades. This would allow to assess the dynamics of amphibian declines in Central and Eastern Europe. The purpose of this study was to establish the species diversity and distribution of amphibians in water habitats of Kozienice Forest. Kozienice Forest (central Poland) has been protected since 1983, when it acquired status of nature park, named Kozienice Landscape Park (KLP) (Fig.1). Fig. 1. Location of Kozienice Landscape Park on the map of Poland. The check-list of amphibian species living in the area of the KLP has never been made. The only available information consists the list of species found over 25 years ago at one site in the vicinity of Pionki town (Juszczyk 1987) and of the short note concerning the habitat of one toad species (Rębiś 1997). The present study, beside producing the first check-list of amphibians that occur in Kozienice Forest, aims also at assessing their commonness or rarity in the area as well as their preferences for the local water habitats of different characteristics. This information will be useful in the future comparative studies aimed at assessment of amphibian decline rates. STUDY AREA, MATERIAL AND METHODS Kozienice Forest (N51 31', E21 26') became known as a part of king economy property in the beginning of XVII century. Together with adjacent forests, it farmed vast woodland area covering all the middle lowland of central Poland (Zielony 1997). In the remnant of that vast woodland, in 1983 the Kozienice Landscape Park was created. Nowadays it has more than 26000 hectares in the area and its buffer zone more than 36000 hectares (Kurowski et al. 2002). The study reported here was carried out in 2003 2005. In the first year, it lasted from the beginning of March to the end of July. In the second year, the time of the study was prolonged to the end of October (excluding August). In the last year, 2005, it lasted from March to the end of May. The study included all kinds of amphibian water habitats encountered in Kozienice Forest.

Amphibia of water habitats in Kozienice Forest 155 The identification of amphibian species was carried out by the following means, used previously by other authors: Recognition of characteristic morphological features of adults during the reproductive season. Green frogs were caught and identified in detail with help of Berger (2000) herpetological atlas (Chobotow & Czarniawski 1999, Rychła et. al. 2002). Identification of male mating calls (Rzępała et. al. 2004). Examination of egg clumps, tadpoles and juveniles found in the water and immediate surroundings. Egg clumps and tadpoles that could not be identified were raised in captivity and later released after identification (Berger 2000, Rychła et. al. 2002). Identification of dead animals found on the roads and in water body surroundings (Rychła et. al. 2002, Trakimas 1999). Interviewing people and forest workers about presence of various species. Any information was verified by observation in indicated water bodies (Chobotow & Czarniawski 1999). The investigations were carried out in 91 selected water bodies potential mating places for amphibian. The knowledge about available water bodies was based on a map of KLP (1:75000) and on information from the Park Staff (M. Kurowski personal information). Care was taken to cover evenly the whole area of the Park and to select water bodies of various sizes in similar proportions as they occur there (Table 1). Each water body was inspected at least three times during each research season. Two inspections took place during day time (the first one in March or April the second one in May or June) and one inspection took place at night (in the end of April or beginning of May). During each day control the water body was first subjected to silent observation from the hiding place, and later its shore and shallows were searched. All signs of amphibian presence were noted down (mating calls, presence of adults, egg clumps and tadpoles). In the first year, only 21 water bodies were investigated; in the next year, those 21 were investigated again and another 58 were added. In the last year, all water bodies from previous seasons were investigated again and another 12 were included into research. Each water body was characterized in several aspects: On the basis of its surface size it was included in one of the three categories: (1) small (to 20m 2 ), (2) medium (20m 2 1 hectare), (3) large (>1hectare). The size was estimated with the use of maps or (in case of small water bodies) by self made measurements. Its distance from human settlements was measured and categorized as (1) short, less than 1.5 km or (2) long, more than 1.5 km. These two categories were distinguished on the basis of information on amphibian movement capability. The distance of 1.5 km during one reproductive season is considered to be the average distance traveled by Anura, and nearly maximum traveled by Urodela (Juszczyk 1987, Blab & Vogel 1999). Three categories of anthropogenic negative influence (human impact) on the water habitats were distinguished: (1) little and incidental influx of pollution left by fishermen or tourists; (2) incidental increase of the load of pollution once per season but in large amount that polluted 20 30% of the water body (for example: organic wastes (communal or agricultural), rubble and containers with remnants of used paints, oils and other chemicals); (3) influx of pollutants as above, but more often than once a season. In the consequence amphibians die. The last studied feature of the water bodies was seasonal change in the water level. It was measured twice, in March or April and May, in the last year of research (2005). The differences in water level were classified into three categories: (1) small change (water surface drops about 20% of the water body depth); (2) medium change (water surface drops considerably, but the depth still is about 60 cm or more); (3) large (the water body dries totally or only separated puddles remain).

156 M. J. Dąbrowski and W. Strużyński Table 1. Studied features of all 91 water bodies, during three year studies (2003 2005), in Kozienice Landscape Park. Amphibian species present in the water body Characteristics of water bodies Number of water bodies R. esculenta R. temporaria B. bufo R. lessonae R. arvalis H. arborea P. fuscus R. ridibunda B. calamita B. bombina T. vulgaris B. viridis T. cristatus Surface size Distance from settlements Human impact Water level changes Geographical coordinates of water bodies Name of the closest town or village to each water body 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1 + + 3 2 1 2 N51 30'12.8'' E21 23'42.5'' Karpówka 2 1 2 1 2 N51 30'13.8'' E21 23'34.7'' Karpówka 3 + + 1 2 1 2 N51 30'08.6'' E21 23'51.7'' Karpówka 4 + + + 3 2 1 1 N51 30'01.9'' E21 22'23.1'' Karpówka 5 + + + + + 3 1 2 1 N51 29'28.3'' E21 29'48.1'' Januszno 6 + + + 2 1 2 2 N51 29'32'' E21 29'43.7'' Januszno 7 + + + 1 2 1 3 N51 30'26.6'' E21 29'33.4'' Osowie 8 + + 1 2 1 2 N51 30'25.1'' E21 29'46.3'' Osowie 9 + + + + 1 1 3 2 N51 31'50.1'' E21 27'58.7'' Augustów 10 + + + + + 1 1 3 2 N51 31'46.6'' E21 28'09.9'' Augustów 11 + + + 1 1 3 3 N51 31'57.1'' E21 28'31.5'' Augustów 12 + + 1 1 3 3 N51 31'56.4'' E21 28'44.8'' Augustów 13 1 1 1 3 N51 31'28.3'' E21 29'09.5'' Augustów 14 + + 1 1 2 3 N51 31'26.5'' E21 28'58.4'' Augustów 15 + + 1 1 2 2 N51 31'28'' E21 28'45.8'' Augustów 16 + + + 3 1 1 1 N51 28'14.3'' E21 27'08.4'' Pionki 17 + + + + + + 2 1 2 2 N51 27'24'' E21 28'44.4'' Kolonia Suskowola 18 + + + + 2 1 2 2 N51 29'46.9'' E21 34'04.1'' Bogucin 19 + + + + + + + 1 2 1 1 N51 32'16.3'' E21 28'33'' Augustów 20 + + + + + + + 2 1 2 2 N51 29'12.5'' E21 23'35.4'' Jedlnia 21 + + + + 1 2 2 2 N51 30'02.9'' E21 25'47.8'' Pionki 22 + + + + 1 2 2 2 N51 31'44.1'' E21 24'58.7'' Posada 23 + + + + + 3 2 1 1 N51 31'26'' E21 23'31.9'' Posada 24 + + + + + 3 2 1 1 N51 31'22'' E21 23'08'' Posada 25 + + + + 3 2 1 1 N51 31'08.3'' E21 23'59.6'' Posada 26 + 1 1 2 1 N51 32'15.7'' E21 23'01.9'' Przejazd 27 + + 2 1 2 1 N51 32'14.5'' E21 23'40.5'' Przejazd 28 + + 1 2 1 3 N51 33'04.1'' E21 22'16.9'' Cecylówka 29 + + 1 1 1 3 N51 34'13.5'' E21 22'25.8'' Ursynów 30 1 1 1 3 N51 34'22.5'' E21 21'52.4'' Ursynów 31 1 1 2 3 N51 35'46.2'' E21 20'58'' Przecinka 32 1 1 2 1 N 51 35'55.5'' E21 20'50.2'' Brzóza 33 + 3 1 2 1 N51 35'56.5'' E21 20'56.9'' Brzóza 34 + + 2 1 2 1 N51 35'56.2'' E21 21'00'' Brzóza 35 + + 1 2 1 3 N51 34'48.5'' E21 23'23.9'' Stanisławów 36 + + + + 1 1 1 1 N51 30'53.1'' E21 20'16.1'' Stoki 37 + 1 1 2 3 N51 30'13.5'' E21 21'07.6'' Stoki 38 + + + 1 1 1 1 N51 29'03.4'' E21 20'01.4'' Zadobrze 39 + + + + 2 1 3 3 N51 28'06.1'' E21 20'46.1'' Poświętne 40 + + + 1 1 2 1 N51 27'56.1'' E21 20'58.2'' Kieszek 41 + + + + 1 1 1 1 N51 25'49.5'' E21 34'58.2'' Antoniówka 42 + + + 1 1 1 1 N51 25'34.9'' E21 34'55.7'' Antoniówka 43 + + 1 1 1 2 N51 25'32.8'' E21 34'58.8'' Antoniówka

Amphibia of water habitats in Kozienice Forest 157 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 44 + + + + 1 2 1 1 N51 26'06.6'' E21 34'00.8'' Antoniówka 45 + + + + + + + 2 1 1 1 N51 26'05.1'' E21 34'14.7'' Antoniówka 46 + + + + 3 2 1 1 N51 25'59.7'' E21 34'00.4'' Antoniówka 47 1 1 1 2 N51 26'43.7'' E21 34'29.1'' Patków 48 + + + + + + 2 1 2 2 N51 26'30'' E21 33'49.8'' Patków 49 + + + + + + + + 1 1 2 1 N51 26'30'' E21 33'53.2'' Patków 50 + + + + 1 1 2 1 N51 26'30'' E21 33'55.4'' Patków 51 + + 1 1 2 1 N51 26'30'' E21 33'58.5'' Patków 52 + + 2 1 2 1 N51 26'30'' E21 33'62.3'' Patków 53 + + 1 1 2 1 N51 26'34'' E21 33'64.1'' Patków 54 + + + + + 2 1 1 2 N51 27'25.4'' E21 28'55.9'' Kolonia Suskowola 55 + + + + + + + 3 1 1 1 N51 26'50.6'' E21 33'34.8'' Stasiów 56 + + + + + + + + 1 1 2 1 N51 26'41.7'' E21 35'42.9'' 57 + + + + 1 1 2 1 N51 26'47.3'' E21 36'23'' Las Las 58 + + + + + 3 2 1 1 N51 28'18.4'' E21 34'58.5'' Cyganówka 59 + + 1 2 1 1 N51 28'21.1'' E21 34'49.5'' Cyganówka 60 + + + + 2 2 1 1 N51 28'44.5'' E21 33'21.7'' Żytkowice 61 + + + 1 1 2 3 N51 31'31.4'' E21 27'43.8'' Augustów 62 + 1 1 3 3 N51 31'30.4'' E21 27'53.4'' Augustów 63 + + + 1 1 2 3 N51 31'30.1'' E21 27'48.2'' Augustów 64 + + + + 1 1 1 3 N51 32'00.5'' E21 27'26.5'' Augustów 65 + + 1 2 1 3 N51 27'34.2'' E21 16'10.9'' Kozłowska 66 + + + 3 2 2 1 N51 27'29.1'' E21 16'22'' Kozłowska 67 + + + 2 2 1 1 N51 27'27.7'' E21 16'31.6'' Kozłowska 68 + + + 2 2 1 1 N51 27'25.8'' E 21 16'24.4'' Kozłowska 69 1 2 1 2 N51 27'26.8'' E21 16'14.8'' Kozłowska 70 + + + 3 1 2 1 N51 29'32'' E21 13'52.2'' Jastrzębia 71 + + + + + + + 3 1 2 1 N51 30'49.2'' E21 35'43.7'' Molendy 72 + + 1 2 1 3 N51 30'23.5'' E21 35'29.5'' Molendy 73 + + + 1 1 3 3 N51 31'47.1'' E21 28'43.7'' Augustów 74 1 1 2 2 N51 31'39.9'' E21 28'17.6'' Augustów 75 + + 1 1 2 3 N51 32'50.7'' E21 24'15.4'' Marianów 76 + 1 1 2 1 N51 32'20.7'' E21 23'55.4'' Przejazd 77 + + + 1 1 2 3 N51 33'24.2'' E21 23'42.5'' Marianów 78 + + + + 1 1 2 3 N51 33'58.9'' E21 23'54.7'' Stanisławów 79 + + 2 1 2 1 N51 34'14.6'' E21 23'59.1'' Stanisławów 80 + + + + 1 1 1 1 N51 31'41.1'' E21 28'37.5'' Augustów 81 + 1 1 2 3 N51 31'24.6'' E21 27'37.5'' Augustów 82 + + + + 1 1 1 1 N51 26'16.5'' E21 28'31.1'' Sałki 83 + + + + + + 2 1 1 1 N51 26'16.7'' E21 28'22'' Sałki 84 + + + + 1 1 2 2 N51 27'23.2'' E21 28'24.3'' 85 + + + 2 1 1 1 N51 26'22.9'' E21 35'48.3'' Kolonia Suskowola Las 86 + + + 1 1 1 2 N51 28'58.7'' E21 36'24.3'' Ponikwa 87 + + + + + + 2 1 1 1 N51 27'03.3'' E21 27'25.9'' Płachty 88 + + + + 1 1 2 2 N51 26'17.7'' E21 29'09'' Mireń 89 + + + + + + 3 1 2 1 N51 23'57.9'' E21 26'06.7'' Helenów 90 + + + + + + 3 1 1 1 N51 23'55.5'' E21 27'01.9'' Helenów 91 + + + + 2 2 1 2 N51 23'46.1'' E21 25'08.2'' Kuczki Duże

158 M. J. Dąbrowski and W. Strużyński For statistical analysis the Statistix program was used. The correlation of different features of water bodies were calculated by Pearson s correlation. One-Way ANOVA was used to find statistically significant differences, between water bodies features, inhabited by 5-8 amphibian species and inhabited by 0-1 species. To recognize amphibian habitat preferences the Chisquare test was applied. RESULTS Characteristics of water bodies inhabited by amphibians Among 91 studied water habitats most (>60%) were small; and more than 70% were located closer than 1.5 km to human settlements. Only seven water bodies (8%) were categorized as highly devastated by human impact. In half of all water bodies the seasonal water level changes were small, in 25% they were medium and in 25% high (Table 2). Table 2. Characteristics of 91 freshwater habitats investigated in Kozienice Forest. See text for detailed criteria used for assessment of their size, water level changes and negative anthropogenic influence. Water body features Water body surface size Distance from settlements Negative anthropogenic influence Seasonal water level changes Category Small Medium Large >1.5 km <1.5 km 1 2 3 1 2 3 Number of water bodies 56 19 16 26 65 44 40 7 45 23 23 Percentage 61 21 18 29 71 48 44 8.0 49 25.5 25.5 For all 91 water habitats, the correlation between different features was calculated (Pearson s correlation) to account for possible interdependence between studied factors. Statistically significant negative correlation was found between the surface size and seasonal changes in water level (r = -0.47; p = 0.0001), as well as between two other factors: distance from settlements and negative anthropogenic influence (r =-0.48; p = 0.0001). As could be expected, in small water habitats the water level was more variable than in larger water bodies. Moreover, the water bodies located closer than 1.5 km to settlements were more exposed to human impact which led to negative disturbances of the habitats. 25 20 number of water bodies 15 10 5 0 0 1 2 3 4 5 6 7 8 number of amphibian species Fig. 2. Number of different amphibian species coexisting in 91 investigated water bodies.

Amphibia of water habitats in Kozienice Forest 159 In 83 studied water bodies, the presence of one to eight different amphibian species was stated; in 8 no amphibians were found (Fig.2). Two to four amphibian species most often coexisted in one water body. Greater species richness (5 8 species) was noted only in 21% of habitats (see Fig. 2). It was found, with respect to analyzed characteristics that water bodies without or only with one amphibian species (group 0 1) differed significantly from those inhabited by more species (group 5 8) in two features (internally correlated with each other): seasonal water level changes (ANOVA-test, F = 11.5 df = 1, p = 0.0015) and water body surface size (ANOVA-test F= 19.2 df = 1, p = 0.0001). Most species inhabited larger habitats with small seasonal changes in water level. Species richness, distribution patterns and habitat preferences In the study area, presence of 13 amphibian species was stated: the great crested newt (Triturus cristatus Laurenti, 1768), the smooth newt (T. vulgaris Linnaeus, 1758), the firebellied toad (Bombina bombina Linnaeus, 1758), the common spadefoot (Pelobates fuscus Laurenti, 1768), the common toad (Bufo bufo Linnaeus, 1758), the green toad (B. viridis Laurenti, 1768), the natterjack toad (B. calamita Laurenti, 1768), the tree frog (Hyla arborea Linnaeus, 1758), the pool frog (Rana lessonae Camerano, 1882), the marsh frog (R. ridibunda Pallas,1771), the green frog (R. esculenta Linnaeus, 1758), the common frog (or grass frog) (R. temporaria Linnaeus, 1758) and the moor frog (R. arvalis Nilsson, 1842). Species the most often encountered in the studied water bodies were R. esculenta, R. temporaria and B. bufo (present in 50% and 47% of habitats, respectively). Two other frog species: R. lessonae and R. arvalis were fairly common in the searched waters (>30%) and other species were significantly less common (<20% of water habitats), two newt species and the green toad were the rarest (Fig. 3). Fig. 3. Number of water bodies inhabited by each amphibian species. The same bar pattern indicates affiliation of the species to the same genus or group.

160 M. J. Dąbrowski and W. Strużyński Species preferences for particular habitat features were analyzed (Table 3). It was assumed that if the species in question had no particular preferences, it would occur in the water habitats of certain characteristics with the same frequency as the habitats occurred in the study area (see Table 2). The statistical analysis (Chi-square test) of the habitat preferences could be applied only for five most common species, which were found in more than 30 water habitats. In the case of two species, the frequencies of occurrence were significantly different from expected. For the eight less common species, the data were too scarce for such analysis. Table 3. Relative commonness of amphibian species and characteristics of the water habitats in which they occurred, expressed in numbers (upper row) and frequencies (lower row) of inhabited water bodies and compared to those available in Kozienice Forest. For five common species thick-framed cells occurrence significantly different than expected (Chi-square test, p<0,05); other frequency of occurrence as expected. For eight less common species, framed cells, indicate obvious tendencies for habitat selectivity, which could not be proved statistically due to scare data. * expected frequency based on features of water bodies available for amphibians in the study area (see Table 1). Species (number of water bodies) Distance from Negative anthropogenic Seasonal water level Water body surface size settlements influence changes Small Medium Large >1.5km <1.5km 1 2 3 1 2 3 0.61* 0.21* 0.18* 0.29* 0.71* 0.48* 0.44* 0.08* 0.50* 0.25* 0.25* Rana esculenta 21 15 14 15 35 24 25 1 34 11 5 (50) 0.42 0.30 0.28 0.30 0.70 0.48 0.50 0.02 0.68 0.22 0.10 Rana temporaria 27 10 9 12 34 26 17 3 24 13 9 (46) 0.59 0.22 0.19 0.26 0.74 0.57 0.37 0.06 0.52 0.28 0.20 Bufo bufo 23 12 10 13 32 19 20 6 24 13 8 (45) 0.51 0.27 0.22 0.29 0.71 0.42 0.44 0.13 0.53 0.29 0.018 Rana lessonae 14 13 10 11 26 19 18 0 27 9 1 (37) 0.39 0.36 0.27 0.30 0.70 0.51 0.49 0.0 0.73 0.24 0.03 Rana arvalis 18 6 9 11 22 16 11 6 14 9 10 (33) 0.54 0.18 0.28 0.33 0.67 0.49 0.33 0.18 0.42 0.28 0.30 Hyla arborea 11 1 6 4 14 8 9 1 11 3 4 (18) 0.61 0.06 0.33 0.22 0.78 0.44 0.50 0.06 0.61 0.17 0.22 Pelobates fuscus 10 7 0 2 15 9 3 5 8 5 4 (17) 0.59 0.41 0.0 0.12 0.88 0.52 0.18 0.30 0.47 0.30 0.23 Rana ridibunda 3 5 6 6 8 7 7 0 10 4 0 (14) 0.21 0.36 0.43 0.43 0.57 0.50 0.50 0.0 0.71 0.29 0.0 Bufo calamita 7 4 1 1 11 5 7 0 6 2 4 (12) 0.58 0.33 0.09 0.09 0.91 0.42 0.58 0.0 0.50 0.17 0.33 Bombina bombina 3 4 4 1 10 5 6 0 8 1 2 (11) 0.28 0.36 0.36 0.09 0.91 0.45 0.55 0.0 0.73 0.09 0.18 Triturus vulgaris 6 1 0 3 4 4 2 1 4 2 1 (7) 0.86 0.14 0.0 0.43 0.57 0.57 0.29 0.14 0.57 0.29 0.14 Bufo viridis 3 1 0 1 3 1 3 0 2 1 1 (4) 0.75 0.25 0.0 0.25 0.75 0.25 0.75 0.0 0.50 0.25 0.25 Triturus cristatus 3 0 0 1 2 2 0 1 2 1 0 (3) 1.0 0.0 0.0 0.33 0.67 0.67 0.0 0.33 0.67 0.33 0.0 According to Table 3 and to the information concerning characteristics of water habitats available for amphibians of Kozienice Forest (see Table 2), the preferences of different species were as follows: two frog species R. esculenta and R. lessonae belonging to the category of green frogs showed statistically significant preference for larger water bodies with small seasonal changes in the water level. Similar tendencies were observed in the marsh frog (R. ridibunda), also belonging to the category of green frogs and in the fire-bellied toad (B. bombina).

Amphibia of water habitats in Kozienice Forest 161 Two other frog species (R. arvalis and R. temporaria) belonging to the group of brown frogs, did not show any significant preferences for the analyzed habitat features. Three rarest species T. vulgaris, T. cristatus and B. viridis evidently preferred small water habitats, avoiding larger water bodies. DISCUSSION The commonness or rarity of particular species was based in our study on frequency of their occurrence in water habitats available to amphibians in Kozienice Forest. According to many research concerning different species this criterion is usually positively correlated with the size of the species population (Gaston 1994, Yu & Dopson 2000, Krystufek & Griffiths 2002). The results presented above can be compared with the previous assessment of species richness in one locality of Kozienice Forest and of similar assessments carried out in some other protected areas in Poland, of similar woodland character. The comparison of current results with the previous ones (Juszczyk 1987, Rębiś 1997) showed that generally species richness in Kozienice Forest has not changed for last 20 years, although in a single site near Pionki town examined in the past by Juszczyk, presence of three species (B. calamita, T. cristatus, T. vulgaris) previously described now could not be confirmed. This may indicate that the ranges of some species have contracted since the time of earlier studies. According to criteria used in this study, the most common species in Kozienice Forest were: R. esculenta, R. temporaria and B. bufo, slightly less common were R. lessonae and R. arvalis. Relatively rare species were H. arborea, P. fuscus, R. ridibunda, B. calamita, B. bombina. The rarest were B. viridis, T. vulgaris T. cristatus. In comparison to amphibian abundance described for other woodland nature parks, e.g. Janów Forest, Krzczonów Landscape Park and Przemków Landscape Park (Chobotow & Czarniawski 1999, 2001; Rychła et al. 2002), the main difference concerns B. bombina species quite common in those Parks and fairly rare in Kozienice Forest. B. bombina prefers rather shallow, warm water bodies, with stable water level (Hofman & Szymura 1998) and is very sensitive to lack of water, it can only withstand about 5 hours out of water (Blab & Vogel 1999). This sensitivity strongly restricts its dispersal ability. The land distance over 950m is too long for this species (Juszczyk 1987). Although shallow, warm water bodies are present in Kozienice Forest, but they may be too far from each other, and restrict occurrence of B. bombina in the studied area. Moreover, in neither of those landscape parks R. esculenta was so common as in Kozienice Forest; this may be due to exceptionally good water conditions for this species in the studied area, because for last ten years ground water level has raised considerably (Kurowski et al. 2002). As for habitat preferences of amphibians stated in this study, the most obvious one revealed by green frogs for large and seasonally stable water bodies should be expected, because these frogs spent most of the season in the water (Juszczyk 1987, Berger 2000). In the case of the brown frogs and the common toad, which did not show any particular preferences for the examined habitat features, evidently some other factors, not considered here, limited their occurrence in Kozienice Forest. Similar situation must be in case of three rarest species, the green toad and two species of newts, which showed clear tendency to choose small water bodies. Although such water bodies were very numerous in the area, newts and green frog were only found in few of them. It is well known, however, that in comparison to the 60s and 70s, when the newts were common even in urban areas (Kowalewski 1967), later they became less common.

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