The water dynamics of the Pivka lakes are reflected in various ways, and this is reflected in the great biodiversity. We find an exceptional diversity of flora and fauna here due to the intertwining of the water game, the man who cultivates extensive use of meadows and pastures, and the sub-Mediterranean location. We find special ones in a variety of habitats (habitat types), such as wet and dry meadows, shrubs, forests, and karst caves.
The small fairy shrimp (Chirocephalus croaticus), which is endemic to Petelinjsko jezero Lake and its surroundings, should not be overlooked. Another unique species is the olm or proteus, which lives in the Pivka region’s underground (Proteus anguinus).
On the surface, tadpoles and aquatic insects are mostly found in wet meadows during floods, whereas fragrant flowers, colourful butterflies, and birds thrive during the dry season…
Fish would be expected in the lakes, but there are none due to dry periods, particularly during the summer, when the water hides underground.
Herbs thrive in dry karst meadows, which are also useful in home cooking. Many birds, including the rare Barred warbler, fieldfare, and Red-backed shrike, are secretly watching us in the bushes, which are densely forested with thorns of blackthorn, rosehip, hawthorn, and juniper.
Along the lakes are Javorniki forests, which are home to interesting animals such as deer, roe deer, lynx, wolf, and bear. We must not forget the squirrel that greets us along a footpath or the field hare that runs across the path after we have wandered around the landscape.
Meadows of Pivka intermittent lakes and their use
Extensive wet meadows predominate in the basins of the Pivka lakes, which form lakes more frequently, and extensively cultivated meadows are partially represented, whereas only extensively cultivated meadows are present in the basins that form lakes less frequently. In the hollows, which rarely form lakes, there are extensive dry and semi-dry karst grasslands. These are normally found on the slopes of lake basins.
In general, the central parts of the bottom of the Pivka Lake basins have thicker soil, whereas the marginal parts of the bottom have thin soil, and the hollows of Palško and Petelinjsko jezero Lakes have even rocky soil. “Jamči” have been preserved among the fallow lands at the bottom of the lake basins where fields were once cultivated. Fallows (abandoned, grass-covered fields) are typical of basins that are less frequently lake-like, whereas basins that are more frequently lake-like have no fallow lands or are limited to higher, marginal parts of the bottom and higher lying side basins.
The smaller basins of the Pivka lakes are better maintained; their bottoms are completely mowed, and there are no overgrown areas at the bottom (the exception is Kalsko jezero Lake). Plots are typically mowed in June, whereas some lakes are mowed no earlier than in August. Petelinjsko jezero Lakes has the highest proportion of unmown areas, where the Mouse garlic plant predominates, giving cow’s milk a distinct smell and taste, making the lake’s feed preferred for horses. The majority of pastures have been relocated to the slopes of lake basins.
What threatens the meadows of Pivka lakes?
The main threat to the preservation of nature-important meadows at the bottom of some Pivka lakes basins, namely the Palško jezero, Petelinjsko jezero, Veliko Drskovško jezero, and Kalsko jezero lakes, is overgrowth. In addition to water retention and shallow and rocky soils, the icing of lakes in winter can cause the branches of bushes and trees to break, inhibiting overgrowth. Meadow fertilisation is much less prevalent than overgrowth. Rooted-up meadows indicate the presence of wild pigs.
The driving of motor vehicles off the beaten path endangers the Pivka lakes as well. Driving a motor vehicle on the soaked ground causes damage to the turf.
The term habitat type can be interpreted in a variety of ways. We find several different words for the same concept in our and foreign contributions with nature conservation content – living environment, habitat type, habitat, biotope, ecotype. The authors’ goal is always the same: to bring a wider audience closer to the recognisable living environments in nature that we have been following since childhood.
A plant or animal community as a distinctive living part of an ecosystem associated with inanimate factors (soil, climate, presence and quality of water, light, etc.) in a spatially defined area is referred to as a habitat type.
According to Article 31 of the Nature Conservation Act (Official Gazette of the Republic of Slovenia, No. 96/04 – official consolidated text, 61/06 – ZDru-1, 8/10 – ZSKZ-B, 46/14, 21/18 – ZNOrg, 31/18 and 82/20) a habitat type is defined as a biotope or biotically distinct and spatially complete unit of an ecosystem.
Individual habitat types can be distinguished from the environment even by a non-expert who observes nature with keen interest. At a young age, everyone learns to distinguish the forest from the grassland and the rocks from the water while getting to know their surroundings. These are examples of habitat types of the highest hierarchical level. A more detailed division of habitat types is intended primarily for experienced professionals and largely corresponds with the type of vegetation (individual plant communities or groups of communities).
The following sections describe five habitat types found in the Seasonal Lakes of Pivka Nature Park.
Endemics in the Pivka region
- Fairy shrimp (Chirocephalus croaticus)
When the researchers inventoried the aquatic fauna in the Pivka intermittent lakes, they discovered that it is not particularly diverse, but it contains a number of interesting species. At least three of the crustaceans found in the Pivka lakes area are endemic, and two species have their only locality in Slovenia here. Petelinjsko jezero Lake is critical for the survival of a 12–15 mm crustacean known as the Karst Fairy shrimp (Chirocephalus croaticus). The shrimp was discovered in puddles in Croatia’s Neretva River’s lower reaches, but it could no longer be found there. They later discovered it in two more puddles near Lake Cerknica, but because they buried the area, they also destroyed the fairy shrimp’s environment. They are currently only found in Petelinjsko jezero Lake and Jeredovce Lake. The species can be found in large numbers under favourable conditions. This Petelinjsko jezero Lake and Jeredovce Lake resident is endemic, which means that this species of shrimp can only be found in the Pivka intermittent lakes area in the entire world.
- Olm (Proteus anguinus)
This area is also important for the olm (Proteus anguinus), which lives in the Dinaric-Karst groundwater from the Soča river basin in Trieste to the river Trebišnica in Herzegovina, earning it the name endemic to the Balkans. It is Europe’s sole representative of cave vertebrates.
The species is listed as vulnerable on the Red List of endangered amphibian species and is also protected by the Natura 2000 network.
Plant and animal species
We go over specific plant and animal species from the Nature Park area in greater detail.
The Pivka intermittent lakes area is important for large carnivores due to the presence of large, closed forests. For all three large carnivores – wolf (Canis lupus), bear (Ursus arctos), and lynx (Lynx lynx) – Javorniki are especially important as part of the Snežnik-Javornik massif in connection with the Kočevje forests and the Gorski Kotar forests. They form the largest compact sparsely populated forest complex, which serves as the primary habitat for large carnivores. The jackal is also increasingly present in the area (Canis aureus).
Wolves and bears, in particular, are frequently seen on the lakes, and the wildcat is also present at all times (Felis silvestris).
The significance of large carnivores in nature
Large carnivores are predators that play an important role in regulating ungulate density, as well as the overall functioning of natural ecosystems. Some of them are also scavengers (especially bears), thus performing a sanitary role in the ecosystem. Because some species (such as bears) eat plant fruits, they aid in seed dispersal, increasing the vegetation structure and diversity of the ecosystems in which they live.
The most common cause of plant endangerment is habitat change, but some plants can also be endangered by overharvesting, digging, uprooting. As a result, certain plant species are protected by special regulations. However, we should rather admire plant species in their natural habitat and only take photographs of them.
Representatives of wet meadows
Representatives of dry grasslands