The study took place in the Natura 2000 site ‘Waldviertler Teich-, Heide- und Moorlandschaft’ (Flora-Fauna-Habitat Directive (FFH Directive)) and “Waldviertel” (Birds Directive), in the Lower Austrian Waldviertel region (district Gmünd). The Natura 2000 site includes different priority habitat types defined by the FFH Directive (Ellmauer et al. 1999). The Waldviertel region is at the border of subcontinental and suboceanic climates, characterized by cold temperatures and moderate rainfalls (Jungmeier et al. 2004). The nearest weather station in Litschau (sea level: 558 m) records a mean annual air temperature of 7.1 °C and a mean annual rainfall of 844 mm (ZAMG 2017). The Waldviertel region in the northwest of Lower Austria is part of the Bohemian Mass, characterized by many large acidic-mesotrophic forest peat bogs, dominated by Pinus sylvestris (Steiner 1992; Pfundner 2021). The carbonate-free bedrock is impermeable, which, in addition to the low temperatures typical for this region, forms a low-nutrient and highly acidic soil (Pruckner 2002; Pranjič et al. 2006).

Each of the four investigated peatlands contains water bodies (water-filled peat pools and/or blocked drainage ditches) (Fig. 1). The four sites are acidic, low in nutrients, and supplied by rainwater (Steiner 1992; Pranjič et al. 2006). The main habitats are bog forests with red pine (P. sylvestris) and wild rosemary (Ledum palustre), upland bogs with bog pine (P. mugo) and wild rosemary, and silted-up peat pools.

Figure 1. 

The four investigated peatlands in the Waldviertel region. A. A large peat pool in the Haslauer Moor; B. A blocked, water-filled drainage ditch in Heidenreichstein; C. A silting peat pool in Schrems; and D. A partly silting pool in the Schwarzes Moos.

All four sites are medium to heavily damaged from past peat extraction, and large parts of the Waldviertler peatlands were destroyed by forestry, which, along with neophytes and tourism, continues to threaten them today (Penz 2000; Pfundner 2021). Different restoration projects took place in the Natura 2000 site, which aimed to rewet the peatlands and stabilize the water levels by damming/blocking drainage ditches (Pfunder 2021). From 2017–2021, the four sites, among others, were part of the cross-border INTERREG project “Crossborder Habitat Network and Management,” which aims to restore the peatlands (Pfundner 2021). From 1991–2000 the Worldwide Fund for Nature (WWF) and a LIFE project from 1996–1999 took place at the Haslauer Moor and Heidenreichstein in which dam constructions and clearing of the central peatland areas were conducted to rewet the peatlands (Egger 2000; Seehofer et al. 2003; Ebhart 2011). In the Schremser Hochmoor, from 2003–2006, the project “Ländliche Entwicklung” conducted different restoration steps to rewet the peatland (Provincial Government of Lower Austria, 2009).

The Haslauer Moor (48.82472'N, 15.09889'E (WGS 84)) is located in the municipality Haslau. The peatland had an initial size of about 120 ha, of which only about 30 ha exist today (Egger 2000; Jungmeier et al. 2004). The Heidenreichsteiner Moor (48.85444'N, 15.14444'E (WGS 84)) in the municipality Heidenreichstein is part of the protected landscape (IUCN category V) “Naturpark Heidenreichsteiner Moor,” which is approximately 30 ha large (http://www.moornaturpark.at, accessed on 31.07.2023). The Schremser Hochmoor (48.79861'N, 15.10000'E (WGS 84)), located in the municipality of Schrems and also part of a protected landscape (“Naturpark Hochmoor Schrems”), is the largest of the four peatlands. The peatland is 107 ha in size (Natura 2000 standard data form). The peatland Schwarzes Moos (municipality Brand-Altnagelberg; 48.871944'N, 14.980556'E (WGS 84)) is next to the Czech border. Originally, the peatland was 54 ha in size, but due to the former glass industry and strong forestry, only 1 ha of the peatland is preserved (Pranjič et al. 2006). The site consists of several water-filled peat pools and drainage ditches in different silting stages inside a private forest (Table 1).

According to the herpetofaunistic database of Austria (HFDÖ), six reptile and nine amphibian species are potentially located in the area of the study site: B. bufo (Common Toad), Hyla arborea (European Tree Frog), Ichthyosaura alpestris (Alpine Newt), L. vulgaris (Smooth Newt), Pelophylax kl. esculentus (Edible Frog), P. lessonae (Pool Frog), R. arvalis (Moor Frog), R. dalmatina (Agile Frog), R. temporaria (Common Frog), Anguis fragilis (Slow Worm), Coronella austriaca (Smooth Snake), Lacerta agilis (Sand Lizard), Natrix natrix (Grass Snake), Vipera berus (Adder), and Zootoca vivipara (Viviparous Lizard), of which five species are listed as “vulnerable” by the IUCN (H. arborea, P. lessonae, R. arvalis, C. austriaca, V. berus).

The amphibian assessment took place eight times, mainly focusing on water bodies. As amphibians inhabit different habitats at different life stages, we combined several methods to assess the potential occurring species (Lüscher and Althaus 2009). The assessment started on 15 April 2018 and ended on 30 June 2018, consisting of six different methods: (1) acoustic mapping, (2) spawn mapping, (3) larvae mapping, (4) newt shining, (5) use of fish traps, and (6) visual mapping, which took place in all four study sites. All six mapping steps were planned to take place at the appropriate time, regarding their developmental stage (Cabela et al. 2001). The acoustic mapping took place once in April and once in May, i.e., during the reproductive season when male amphibians call to attract females (Glandt 2008). In each site, we spent a minimum of 30 min. To map the amphibian spawn, we slowly walked along the banks of the water bodies (for 15 min at each water body) at the end of April. The larvae mapping took place twice at the end of May, using a landing net with a mash size of approximately 2 mm. In small water bodies (< 10 m²) we took five strokes, in medium water bodies (ca. 10–30 m²) we took 10 strokes, in large water bodies (ca. 30–100 m²) 15 strokes, and in very large water bodies (> 100 m²) 20 strokes. To record the newts, we slowly walked along the banks of the water bodies after sunset and shone lights through the water for 15 min at each water body. In June, four fish traps were cast in each site to catch tadpoles and newts, which were emptied and dismantled the next morning. Visual mapping took place each time we were at the study site for the mapping steps described above.

In all six mapping steps, we determined the species directly at the study site. In doubtful cases, however, we recorded the amphibian calls with an iPhone SE 5 (acoustic mapping), took pictures with a camera (Nikon D90 or an iPhone SE 5; visual mapping), or took samples in alcohol (98% ethanol) for later determination with a binocular (ZEISS, Stemi SV11) and the identification key provided by Thiesmeier (2014). All people involved in the assessment used rubber boots, which were disinfected after each different study site to prevent spreading chytrid fungus or other transmissible diseases (Schmidt et al. 2009).

The reptile assessment took place from 4 June to 15 August 2018, along the banks of the water bodies, at the open parts of the peatlands (here referred to as moorlands) and their surrounding forests, with each site being visited four times during this period. The mapping consisted of a transect leading through the open moorlands and forests, approximately 400 m in length. The observer slowly moved along the previous determined path (transect) for one hour and mapped all visible reptile species along the transect and approximately 2 m right and left of it, following a zigzag pattern (Fitzgerald 2012). The mapping took place in the morning from 8:00 to 11:00 am or in the late afternoon, after 3:00 pm until 7:00 pm, and was interrupted during rainfall.

To characterize and verify the quality of the habitats, we (1) measured the pH value of each water body in the four sites using an HQd Portable Meter (Hach Lange GmbH, Düsseldorf, Germany) and (2) mapped the microhabitats and calculated an indicator species analysis (ISA). ISA is used to identify species characteristics of specific habitat types within the study site. The analysis was performed using the labdsv package in R Studios. Species with significant indicator values (P < 0.05) were considered strongly associated with specific habitat types, indicating their potential as habitat indicators. The results were interpreted to identify key species representing different habitat types in the study area. Microhabitats are small habitats with vertical and/or horizontal vegetation and landscape structure in a terrestrial and/or aquatic ecosystem (Ricklefs and Miller 1999). The scale for microhabitats used usually ranges from 25–100 m² (Baraloto and Couteron 2010). Microhabitats were defined based on the habitats provided by Cabela et al. (2001) and the results of Ebhart (2011). We drew polygons of each microhabitat based on the orthophotos of GEOLAND basemap (datasource: https://basemap.at/) and hand sketches of each peatland in ArcGIS 10.6.1 (ESRI) geographic information system (GIS) software to assemble microhabitats and the results of the amphibian and reptile assessments for each study site.

Two authorizations by the Lower Austrian government allowed us to catch and collect amphibians and reptiles (Provincial Government of Lower Austria, 3109: Stückler S.: BD1-N-200/021-2004; RU5-BE-64/019-2018; Schweiger S.: RU5-BE-64/018-2018; BD1-N-200/021-2004; NÖ-UA-V-30/004-2015).

In total, we located 1520 individuals (including larvae and spawn) of eight amphibian species in the study site: B. bufo, H. arborea, P. kl. esculentus/lessonae (hereafter grouped and called Pelophylax sp. as the distinction in the field is not reliable), R. arvalis, R. dalmatina, R. temporaria, I. alpestris, and L. vulgaris (Table 2). The species composition and the number of individuals differed in the two main aquatic habitats (peat pools and blocked ditches); in the peat pools, we located B. bufo, Pelophylax sp., R. arvalis, R. dalmatina, R. temporaria, and L. vulgaris. In total, we detected 725 individuals in the peat pools. The most abundant species was Pelophylax sp. (416 individuals; 46.3% of total individuals found), followed by B. bufo tadpoles (250 individuals; 27.8% of total found individuals). In the blocked ditches, B. bufo, H. arborea, Pelophylax sp., R. arvalis, I. alpestris, and L. vulgaris were identified. In total, we detected 174 individuals in the blocked ditches, again with Pelophylax sp. having the highest number of individuals (158 individuals, 17.6% of total found individuals) (see Table 2, Fig. 2).

Figure 2. 

Amphibian species observed in the Waldviertler peatlands: A. Lissotriton vulgaris; B. Ichthyosaura alpestris; C. Bufo bufo; D. Hyla arborea; E. Pelophylax sp.; F. Rana arvalis; G. R. dalmatina, and H. R. temporaria. Pictures A, B, G, H provided by Michael Franzen.

We located 64 individuals of four reptile species in the study sites: A. fragilis, N. natrix, V. berus, and Z. vivipara. In the Schwarzes Moos and the Haslauer Moor, we located three reptile species: A. fragilis, N. natrix, and Z. vivipara. In Schrems we found three species, namely N. natrix, V. berus, and Z. vivipara. Only in Heidenreichstein could we detect all four species: A. fragilis, N. natrix, V. berus, and Z. vivipara (Table 3, Fig. 3).

Figure 3. 

Reptile species observed in the peatlands of the Waldviertel region: A. Anguis fragilis; B. Natrix natrix; C. Vipera berus, and D. Zootoca vivipara. All pictures provided by Michael Franzen.

The lowest pH levels were found in the Schwarzes Moos, while the other three peatlands had higher pH levels (see Table 4, Fig. 4).

Figure 4. 

Comparison of pH values (visualized as strip charts). The peatlands included in the study site are Haslauer Moor (N = 4 pH measurements), Heidenreichstein (N = 3 pH measurements), Schrems (N = 6 pH measurements), and Schwarzes Moos (N = 5 pH measurements). Each point of the strip chart represents the pH level of a measurement point (black) and the mean value (red). For detailed results, see Table 4.

We characterized twelve different microhabitats in the assessment area: open moorland with moss, open moorland with sedges, open moorland with bushes, reeds with water body, water-filled blocked drainage ditch, temporary pond, open water-filled peat pool, silting water-filled peat pool, sparse forest/moor forest, forest, margin, and path (Suppl. material 2). The numbers of amphibian and reptile species ranged from 1–9 per microhabitat type. The ISA did not show any species with significant indicator values. Although species-specific indicator values were calculated, we did not find any significance for any habitat group, suggesting that no species demonstrated a strong preference for a specific habitat in our investigation. In general, silting water-filled peat pools were the microhabitat where we found the most species. We located most amphibian species in silting water-filled peat pools and water-filled blocked drainage ditches, and most reptile species in open moorland with moss, open moorland with bushes, and on paths. We observed Pelophylax sp. in nine, N. natrix in seven, and Z. vivipara in six different microhabitats, whereas I. alpestris only in water-filled blocked drainage ditches (Fig. 5A–C).

Figure 5. 

A. Microhabitats and amphibian and reptile species in Heidenreichstein (1: open moorland; 2: drainage ditch). Circles represent amphibian species; squares represent reptile species. Note the different scales; B. Microhabitats and amphibian and reptile species in 1: Haslauer Moor and 2: Schwarzes Moos. Circles represent amphibian species; squares represent reptile species; C. Microhabitats and amphibian and reptile species in Schremser Moor (1: large water-filled peat pool; 2: open moorland and a silting water-filled peat pool). Circles represent amphibian species; squares represent reptile species. Note the different scales.

Our results show that blocked ditches and peat pools provide aquatic habitats for eight amphibian species. We found higher numbers of individuals in silting water-filled peat pools than in blocked ditches, which might be related to heavy siltation and desiccation of the ditches (Remm et al. 2018). We observed all expected amphibian species in the study site: I. alpestris, L. vulgaris, B. bufo, H. arborea, R. arvalis, R. dalmatina, R. temporaria, and Pelophylax sp., but we did not locate all expected species in each peatland. Bufo bufo, Pelophylax sp., and R. arvalis we recorded in each peatland. Bufo bufo and Pelophylax sp. are very common species with low habitat requirements and are widely distributed across Austria (Cabela et al. 2001). Rana arvalis occurs across the Eurasian subcontinent but is limited in Austria to the eastern and southern lowlands (Glandt 2008). Spawn and larvae of R. arvalis are more resistant to acids than other amphibian species and therefore able to inhabit acidic peatlands (Räsänen et al. 2003; Burmeister 2015). We found several amphibian species in low abundances: I. alpestris, L. vulgaris, R. dalmatina, R. temporaria, and H. arborea.

In the Schwarzes Moos, we recorded the lowest pH levels ranging from 3.2–4.2 (Table 4); nevertheless, we observed calling B. bufo, Pelophylax sp., R. arvalis, and R. temporaria and located R. dalmatina spawn in peat pools. Mortality of many amphibian species increases when pH levels are below 4 (Pierce 1985). Dolmen et al. (2008) reported that low pH levels cause the absence and extinction of amphibians in Southern Norway: pH levels of 4.5–4.6 are critical for R. temporaria, 4.7 was the lowest pH level recorded for B. bufo, and 4.8 for L. vulgaris. Successful reproduction was not observed below 5.2 and 5.3 in R. arvalis and Triturus cristatus (Dolmen et al. 2008). However, pH levels of water bodies are subject to certain fluctuations in relation to, e.g., rainfall (Fraindová et al. 2022); therefore, a more comprehensive abiotic investigation of the water bodies on a long-term basis across the year is necessary to provide more detailed insights into the relationship between pH value and the amphibian fauna in the peatlands and its ecological role. Secondly, a more intensive assessment and an adjustment of monitoring methods might have been necessary to find species that are harder to detect. The two expected newt species (I. alpestris and L. vulgaris) do not call to attract females (Thiesmeier and Schulte 2010; Große 2011), which hampers localization. The use of more fish traps and additional newt-shining surveys could have helped to detect both species in higher numbers in all four peatlands.

Our study verified four reptile species in the Waldviertler peatlands, located mainly in open moorland habitats and on paths. During the reptile assessments that have been carried out at temperatures ranging from 18–27 °C, the most frequently observed reptile species was Z. vivipara (Table 3). We located Z. vivipara in all four peatlands, with the highest total number of individuals of all recorded reptiles. Zootoca vivipara also uses aquatic habitats, mainly to escape from enemies, and can submerge for up to 20 min (Thiesmeier 2013). On hot summer days, Z. vivipara relocates to wet and humid areas (e.g., dense understory) to prevent water loss through transpiration (Buschinger and Verbeek 1970). Similar to these observations, we also located most Z. vivipara between wet moss cushions in open moorlands.

The second most abundant species located in the study site was N. natrix, which we could verify in each peatland. The species is often found near water bodies, likely because N. natrix feeds mainly on frogs (Pelophylax sp., B. bufo, Rana sp.) (Filippi et al. 1996). The second snake species located in the study area was the Adder, V. berus. In Austria, V. berus occurs in the montane-alpine region and in the Bohemian Mass in the north of the country. In the latter area, V. berus mostly occurs in wet meadows and peatlands (Cabela et al. 2001). Vipera berus prefers high temperature variations between day and night, short vegetation periods, high precipitation and/or humidity, and structure-rich habitats (Völkl and Thiesmeier 2002). In peatlands, V. berus needs structures that heat up quickly (Otte et al. 2020). Consistent with these findings, we mostly found V. berus next to dead wood, on moss pads, or between high grass in open moorlands. We did not assess all reptile species that were expected in the area. To estimate the total reptile diversity in the peatlands, further investigations are necessary.