A Landscape-Level Study on the Breeding Site Characteristics of Ten Amphibian Species in Central Europe
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Amphibia-Reptilia 34 (2013): 63-73 A landscape-level study on the breeding site characteristics of ten amphibian species in Central Europe Balázs Vági1,2,∗, Tibor Kovács1, Raluca Bancil˘ a˘3,4, Tibor Hartel5,6, Brandon P. Anthony7 Abstract. Temporary ponds are characterized as being in natural or close to natural states in Central and Eastern Europe, especially those located in forested landscapes. As these ponds function as breeding sites for many amphibians, they represent an ideal target to explore the terrestrial and aquatic habitat preferences of different species. We surveyed 133 small ponds in a forested, hilly region of North-Central Hungary. The occurrence of ten amphibian species and amphibian species richness were compared to six pond-related habitat variables and the extent of four terrestrial habitat types in the area surrounding the ponds. Our results suggest that most species’ occurrence and species richness are chiefly related to pond characteristics, although terrestrial habitat variables could also be a determining factor in particular species. Whereas the majority of amphibian species prefer larger, hence more permanent water bodies with abundant aquatic vegetation, the common frog (Rana temporaria) chooses small, shallow wallow pits for breeding and has special requirements concerning terrestrial habitat composition. This could explain its restricted distribution in the area. Our results suggest that maintaining a diverse set of ponds and forestry management which facilitates habitats’ structural heterogeneity are both important factors for the preservation of the rich amphibian fauna in Central Europe. Keywords: breeding pond use, Hungary, landscape ecology, temporary ponds. Introduction rary ponds fulfil a number of functions at both a local and landscape level. They act as breed- Temporary ponds are important for a number of ing habitats for a number of organisms. Indeed, wildlife species (Williams et al., 2003; Scheffer temporary ponds may have higher species rich- et al., 2006; Scheffer and van Nes, 2007) and ness than permanent ponds due to the absence their persistence depends on various environ- of predatory fish (Scheffer et al., 2006). Further, mental factors. Having a relatively small size, temporary ponds may act as stepping stones for their importance in ecosystems may be under- a number of wildlife species, increasing connec- estimated, and often their disappearance goes tivity at the landscape level (Semlitsch, 2000; unnoticed (Semlitsch and Bodie, 1998). Tempo- Williams et al., 2003; Roe and Georges, 2007). Pond breeding amphibians are an important 1 - Behavioural Ecology Group, Department of Systema- group to address the impacts of the globally tic Zoology and Ecology, Eötvös Loránd University, threatening habitat loss on wildlife (Bender, Pázmány Péter sétány 1 C, 1117 Budapest, Hungary Contreras and Fahrig, 1998; Fahrig, 2003) for a 2 - Lendület Evolutionary Ecology Group, Plant Protection number of reasons, e.g. complex life cycles and Institute, MTA Centre for Agricultural Research, Her- man Ottó út 15, 1022 Budapest, Hungary dependence on both aquatic and terrestrial en- 3 - Institute of Speleology Emil Racovi¸ta,˘ Bucharest, Ro- vironments (Wilbur, 1980; Stuart et al., 2008); mania seasonal migration between habitats (Cushman, 4 - Faculty of Natural Sciences, Ovidius University, Con- 2006); or sensitivity to environmental condi- stan¸ta, Romania 5 - Department of Ecology, Leuphana University, Lüne- tions due to their permeable skin (Feder and burg, Germany Burggren, 1992). As a consequence of these 6 - Sapientia University, Department of Environmental Sci- characteristics, amphibians are in global crisis ences, Cluj-Napoca, Romania (Alford and Richards, 1999; Houlahan et al., 7 - Environmental Sciences and Policy Department, Central European University, Nádor u. 9, Budapest 1051, Hun- 2000), with habitat degradation and loss being gary the most important drivers of their decline in the ∗Corresponding author; e-mail: [email protected] Northern Hemisphere (Stuart et al., 2004). © Koninklijke Brill NV, Leiden, 2013. DOI:10.1163/15685381-00002869 64 B. Vági et al. Considering their life history particularities, relevant for the maintenance of a diverse am- the habitat use and occurrence of pond breeding phibian assemblage, as well as suitability for amphibians can be best understood by simulta- each species. neously examining pond-related and terrestrial Here we present a case study of amphibian habitat-related variables (Marsh and Trenham, habitat in a forested area of Hungary. The ponds 2001). An increasing number of studies use this of this area have a temporary character and approach to explore amphibian occurrence. In have a rich amphibian fauna. We focus both Europe, the majority of these studies were car- on individual amphibian species and species ried out in the western part of the continent richness. where landscape fragmentation (e.g. due to in- tensive agriculture, increasing urbanization and road networks) was generally well pronounced, Materials and methods including Switzerland (Pellet, Guisan and Per- Study area description rin, 2004; Van Buskirk, 2005; Zanini, Pellet and Schmidt, 2009), Italy (Ficetola and De The study was conducted in the Pilis-Visegrád Hills (Pilis), located in North-Central Hungary within an area of Bernardi, 2004; Ficetola, Padoa-Schioppa and ∼300 km2 (fig. 1). Pilis is a moderately elevated range, the De Bernardi, 2009), Belgium (Denoël and Fice- highest peak reaching 756 m above sea level, the altitude tola, 2007, 2008), Netherlands (Laan and Ver- above 600 m representing less than 5% of total area. The boom, 1990; Vos and Chardon, 1998), England Hills comprise two geologically different parts – Visegrád Hills on the northeast consist of mainly igneous rocks while (Scribner et al., 2001), Ireland (Marnell, 1998), the Pilis range at the southwest is made of limestone. As France (Joly et al., 2001; Denoël and Lehmann, a consequence, surface water bodies and streams are more 2006; Curado, Hartel and Anrtzen, 2011), and abundant in the northeastern part of the study area. The hy- drology of the area is characterized mostly by temporary Sweden (Piha, Luoto and Merilä, 2007), but see ponds, in addition to 10 small permanent streams. Indermaur et al. (2010). The Central and East- The vegetation is mixed, consisting chiefly of deciduous ern European region is still scarcely covered forests although scattered hay meadows are also present. by such studies, although some have been un- The oak forests of the lower altitudes are dominated by Turkey Oak (Quercus cerris L., 1753) and Sessile Oak dertaken in Poland (Babik and Rafinski,´ 2001), (Q. petraea [Matt.] Liebl., 1784). The moderately elevated and central Romania (Hartel et al., 2009, 2010a, zones are covered mainly with mixed forests with oak 2010b). All these studies highlight the impor- species as above as well as Hornbeam (Carpinus betulus L., Fagus sylvatica tance of traditional land use for the preserva- 1753). Pure Beech ( L.) stocks cover large parts of the northern slopes, the cooler valleys and the most tion of amphibians. Ecosystems and landscapes elevated zones. are considered to be generally less impacted by The Pilis ponds have either natural or artificial origin, anthropogenic activities in this part of Europe those with the latter were established to provide drinking water for domestic animals and game at least 50 years (Palang et al., 2006; Hartel et al., 2008) there- ago. Due to the changes in land use and decreasing stock- fore this region offers the opportunity to explore raising artificial ponds lost their significance in farming, the ecology of amphibian habitat use (e.g. Har- hence their regular maintenance ceased. Nowadays all the tel et al., 2010a, 2010b). Understanding envi- ponds are governed primarily by natural processes. The pond maintenance activities of the forestry authority are ronmental factors governing amphibian habitat restricted to occasional sediment removal in a few ponds. use is important in Central Europe also because Most of the ponds in Pilis Hills have a temporary char- this region currently faces human-induced habi- acter and, as a consequence, fish are absent; however, in years with above-average precipitation they retain water all tat changes, e.g. habitat fragmentation (Csorba, year round. The surface of these small water bodies ranges 2008; Kovács, Vági and Török, 2010) and cli- from 10 to 6000 m2 and their depth rarely exceeds 50 cm. mate change (Bartholy and Pongrátz, 2007). It Accumulating sediment could be significant in the ponds; is of great importance to know what features sometimes the benthic sediment is 2-3 times deeper than the water column above. The average altitude of the ponds of an area with scarce human impact and es- is ∼400 m, only five of them being above 600 m and none pecially what breeding pond characteristics are above 700 m. Breeding site characteristics of amphibians 65 Figure 1. Location of the surveyed ponds in the region. The area with grey diagonal fill represents the area of Pilis-Visegrádi Hills. All the surveyed ponds are represented by circles, where the size of the circle represents the pond surface area, and the grey tone indicates the species richness (see legend). The thick black lines represent the Danube River. On the inset map: location of the study area in Hungary. Amphibian surveys and variables selection We characterized each site with 6 pond and 4 terrestrial variables (table 1). Approximate pond surface area was cal- Surveys were made in 133 ponds in 2010. We included culated from length and width measurements (to the nearest all known lentic water bodies of the area in our study, ex- 1 m) taken by laser range finder (Precaster Enterprises Co., cept those two large reservoirs, which contain fish. Each pond was visited at least twice between March and July: Taichung, Taiwan). On each study spot we drew an approx- once during the breeding season of early-breeding amphib- imate line map of the pond and surface area was estimated ians (March and April), and a second time during May, by assuming an elliptic or rectangular shape.