Beetles constitute no less than a third of all species currently known on Earth, and Ground Beetle (Carabus variolosus) is just one of them. It is estimated that around 6,000 different beetle species live in Slovenia, many of them endemic, inhabiting only our karst caves and no other place in the world. Ground Beetle, however, is still a widespread species in Slovenia, although occurring in small numbers. It inhabits small, naturally preserved forest streams and narrow strips of extremely wet banks. This kind of marshy deciduous forest is overgrown with willow (Salix sp.), common alder (Alnus glutinosa), common ash (Fraxinus excelsior), beech (Fagus sylvatica) and hornbeam (Carpinus betulus) stands.
Periods of drought can badly affect Ground Beetles, particularly in the developmental stage of their pupae, when mortality greatly increases owing to dehydration or defects in their development. Their space for reproduction and development from eggs through larvae to adult animals is spatially highly limited. Their existence is further threatened by humans, especially through inappropriate floodplain forest management and encroachments upon forest streams. Any such encroachments upon marshy and shady environments of forest streams seriously contribute to the diminishing and fragmentation of the species' habitat.
To conserve the Ground Beetle, the project will provide for restoration and conservation of water and land habitats and their interconnection. We will improve the water flow rate of some filled and dry river branches and provide for more water in wetlands and floodplain forests. Thus we shall also contribute to the reduction of flood risks in the area, as well as to people’s and visitors’ awareness as to why we need to conserve wetlands, floodplain forests and natural forest streams.
What can we do to preserve and improve the habitat of Ground Beetle and other endangered beetles?
- In the process of forest management we should leave part of dead trees in the forest. By preserving dead standing and fallen trees, we shall take care not only of preserving the habitat of endangered beetles, but also of other organisms that provide for natural balance and a healthy forest.
- Trees along the banks of watercourses should not be felled, as they prevent erosion and evaporation of water from streams during the dry season. In this way, we shall nurture a good condition for the Ground Beetle as well.
- We should not encroach upon forest streams with new forest roads. Neither should we throw wood residues and branches into the streams, for this causes flood dangers as well as destroys the Ground Beetle’s habitat. Furthermore, no wood should be stored in streambeds.
- We should not pollute watercourses, and neither should we use fertilizers and phytopharmaceutical agents in the riparian zone of watercourses. In this way, we will maintain the natural balance, a favourable habitat for water invertebrates, amphibians and fish.
Why do we need beetles?
- Beetles constitute an order of insects that carry out a variety of functions in the ecosystem and thus provide favourable living conditions for many other organisms. Several beetle species are indispensable in nature. They are pollinators, take part in biomass decomposition, which enables soil formation. Many species are predatory and take part in garden pests’ control. Ground Beetles, too, are predatory species feeding on other invertebrates, crustaceans, other insects and molluscs.
- Ground Beetle is an indicator of pristine forest streams’ conservation status. It is highly sensitive to the regulation and consolidation of watercourses, damming and draining of streams and forest areas. By destroying natural watercourses, consolidating, polluting and cutting down riparian vegetation, we shall destroy its habitat and, in turn, making it to disappear soon.
Sources and literature
- Marinček, M. (2010). Močvirski krešič (Carabus variolosus, Fabricius, 1787) (Coleoptera: Carabidae) na območju Slovenskih goric (Diplomsko delo).
- Vrezec, A., Polak, S., Pirnat, A., Kapl,a A., Denac, D. (2008). Izvajanje spremljanja stanja populacij izbranih ciljnih vrst hroščev v letu 2008 in 2009 in zasnova spremljanja stanja populacij izbranih ciljnih vrst hroščev. Ljubljana: Nacionalni inštitut za biologijo.
- Vrezec, A., Ambrožič, Š., Kapla, A. (2016). Monitoring populacij izbranih ciljnih vrst hroščev v letih 2016 in 2017. Prvo delno poročilo. Ljubljana: Nacionalni inštitut za biologijo.
- Vrezec, A., Ambrožič Ergaver, Š., Kapla, A., Kocijančič, S. (2018). Dodatne raziskave kvalifikacijskih vrst Natura 2000 ter izvajanje spremljanja stanja populacij izbranih ciljnih vrst hroščev v letih 2018, 2019 in 2020. Prvo delno poročilo. Ljubljana: Nacionalni inštitut za biologijo.