The objective of the Claustra+ project is (among other things) to show that the Roman barrier walls are interesting, attractive and worth visiting. If we put something on a tourist map, we can reasonably expect an increased visit. This, however, can disturb or even adversely affect nature and its inhabitants. The role of the Institute of the Republic of Slovenia for Nature Conservation (ZRSVN) in the project is also to take care of directing the visit in nature.

Live interpretation (photo: U. Galien, archive ZRSVN).

We pay attention to larger groups of visitors, individual enthusiasts, those who spend the night in nature as well as parking (not to even talk about disposed waste and wild toilets). Animals need peace while they are mating, nesting, eating and raising their offspring. By walking in nature, we are destroying their living space, their shelters and their places for eating. The same goes for plants that cannot escape the soles of man’s shoes. By pulling and tearing them, we are directly destroying them, which can cause a collapse of the population of rare and endangered species.

Parking in nature is a special topic that has been tackled by many environmentalists and experts. The fact is that vehicles by trampling the ground cause direct damage and consequently the destruction of natural ecosystems, while indirectly causing pollution with their noise and exhaust gases. Let us also not forget that one or two parked cars are enough to make people follow their example – the next weekend there may be significantly more of them and the following weekend even more. The trampled surface is thus constantly expanding and eating into nature. In the overall arrangement of the development of a tourist destination and directing of the visit, parking spaces should be foreseen and arranged. If we expect the arrival of buses, we should also think of larger areas, which are also suitably hardened (maybe even a bit farther away from the destination).

The aim of the ZRSVN in this project is, therefore, to direct the tourist visit from the most sensitive and critical areas to less burdened and appropriately regulated areas that are adapted to a larger visit. This can be done by arranging access routes, benches, fences and information boards or other modern didactic tools. Preventing access is often less effective than directing in more pleasant manners. Visitors prefer to walk on trail covered in sand or chopped wood than an overgrown path. If there is a bench or information board along the way, the choice is all the more reliable.

People prefer to move around in areas where they feel safe. This can also be ensured by proper forest management (preventive felling of dangerous trees, preserving interesting trees, ensuring the diversity of tree species, time adjustment of forest works). For directing the visit, it is sometimes appropriate to conduct a veduta felling and to remove the trees or shrubs that obscure the views of the surrounding area. This makes it easier to expose and highlight the access to the Roman wall, waterfall, rocks, etc. Only the most enthusiastic individuals are willing to tread through the dense undergrowth, which may even have thorns.

Interpretative panels in Benete (photo: U. Galien, archive ZRSVN).

It is of utmost importance that the local population adopts the nature in the vicinity of a tourist destination. If the locals treat it well, visitors will also be able to capture this pulse more easily. We are talking mainly about the dumping of local waste into a forest or a sinkhole, the use of wildfire pits, breaking of trees and disrespectful behaviour. If you ask a local for information, you will already learn from his or her behaviour what he or she thinks about the destination and the nature (“Oh, there is some wall over there” or maybe “Yes, a wall on which you can see where the soldiers peaked out 1700 years ago.” Notice the difference?). Local guides will surely provide you with a more enthusiastic guiding than the guides from a distant larger city. It is also very sensible to involve children from local schools, who knows which one of them will be the future mayor or urbanist.

We must not forget, however, that it is crucial to take into account the time rules in nature. Everything functions cyclically and repeats itself so that it should not be difficult to determine the flowering time of Carniolan primrose or the arrival of bears from their den. The species are differently susceptible to disturbances in their living space, so directing of the tourist visit to the natural environment must be adapted accordingly.

With regards to this term, we first consider the number of plant and animal species in a country or a region, but the concept of biodiversity also covers the diversity of living spaces or habitats of plants and animals. Biodiversity also includes genetic diversity, that is, diversity among individual specimens of a species. Similarly, as people differ from each other in terms of height, figure, colour and curliness of hair, physical abilities, leisure activities, interests and many more, the animals of the same species always differ slightly from one another.

Diversity on the meadow (photo: M. Vernik, archive ZRSVN).

Why is diversity among members of the same species important? Because, under varying conditions in nature, different adaptations are required at different times. Let us consider an example of seeds: in nature, all of the seeds rarely sprout at the same time. Some sprout fast; such a plant can grow rapidly, blossom early, produce a large number of seeds and will leave a large number of offspring in favourable weather. However, in the case of spring frost, such a young plant will die. On the other hand, its peer will survive, because it is slower, perhaps less lush, and it sprouted late – when frost had already passed. If all the seeds of a species were to sprout early, all the young plants would die in the event of frost. And if all the plants sprouted, grew, blossomed and reproduced slowly and late, they might run out of time to produce their offspring – seeds, in the year when the winter starts unusually early, and the species would not survive. Nature sometimes encourages certain characteristics and at other times, different characteristics. The diverse characteristics among individuals of the same species make it possible for a part of the specimens to survive despite the changing conditions in the environment. Biodiversity is therefore particularly important in times of climate change!

Species that are not edible, useful or otherwise advantageous to humans are also a necessary part of the ecosystem; they have their place in the food chain in the natural ecosystem. In the pre-industrial era, the influence of man on nature was relatively small. The achievements of civilization brought about an increase in the number of people and accelerated use of natural resources, which caused the changing and shrinking of natural habitats. Due to the construction, the expansion of settlements and fields, mining of minerals or clearing of forests, natural habitats disappear completely. Other human activities, such as felling, mowing, pasturing, navigation and recreation are changing these habitats.

Preserved biodiversity is the basis for the widest range of ecosystem services that are essential for people’s lives. In their natural environment, plants and animals offer us the following ecosystem services:

  • plants produce oxygen and use carbon dioxide – this process is particularly intensive in forests;
  • they bind and decompose pollutants, with wetlands being particularly effective – they act as cleaning plants for the emissions of civilization;
  • they clean the air and water;
  • they protect us against floods, as wetlands and areas by the water serve as a spillway for growing waters;
  • they prevent erosion because plants strengthen and retain the soil with their roots;
  • they provide food, as the organic matter and thus all our food originate from plants, most of which are pollinated by animals;
  • the formation and development of fertile soil is the result of the functioning and dying of living beings;
  • and, last but not least, the preserved nature gives us the opportunities for recreation, a break and relaxation, which affects the physical and mental health of people and hence the healthcare budget.

    Bear family on the road (photo: U. Galien, archive ZRSVN).

Nature has a wonderful feature of self-cleaning, self-renewal and development. However, only until our exploitation remains within the limits of sustainable use.

It is very difficult to imagine that everything in nature is interconnected, interdependent and that these connections are very complex. Butterflies, beetles, snails and tiny insects in the soil are small, but indispensable components of man’s habitat, which must maintain balance, the power of renewal, cleaning and growth so that people can survive. Insects must pollinate our produce; aquatic vegetation, snails, the Turbellaria, crabs and other small organisms must maintain the self-cleaning power of our rivers. For us perhaps unimportant beetles must remain the food for birds and bats, which will ensure that unpleasant or harmful insects do not reproduce too much, etc. Plants must maintain the amount of oxygen in the atmosphere in which we have developed and which is suitable for our life. The intertwinement of relations between the organisms forms a solid framework of a pyramid, at the top of which is the well-being of man. We do not measure the well-being only in money and the belief that the missing elements of nature can be replaced without damage with artificial structures is an illusion.

The consequences of the disappearance of a species of butterfly are not immediately apparent. Some stones may be removed from the pyramid without major consequences, but we have already stolen many of them. We do not know when this framework will collapse; but today we already know for sure that it will. We are aware that the diversity of species and habitats gives nature the stability on which we depend. This stability means that the resources we are accustomed to are available to us – drinking water, suitable climate, food and crops. What the ruined stability of nature means for us is the occurrence of unforeseen and unpredictable events.

Today, despite the complexity of nature and our not understanding of all the details, we still know enough so that ignorance can no longer be an excuse. We simply cannot afford to be indifferent!

Nature is changing and will survive, as it has survived despite numerous catastrophes in the history of the Earth. After each crisis, evolution gained a new momentum: the predominant species left, they were replaced by new ones; nature remained, only slightly different than before. Will in the current crisis, which can be characterized as the new era of the great extinction of species, nature again erase the predominant species? It is certain that evolution will continue.

Gozd (foto: D. Klenovšek, arhiv ZRSVN).
Forest (photo: D. Klenovšek, archive ZRSVN).

Forests are an extremely diverse group of ecosystems found on all continents except Antarctica. They cover extremely diverse sites from dry to flood areas and marshes, from lowlands and coastal areas to mountains; in the Himalayas, they reach the altitude of about 4,000 m. If not for the deforestation in the past, they would probably cover most of Central Europe. Forest is a source of material goods – wood, forest fruits and wildlife, providing food and fuel for a proportion of mankind. It gives us space for recreation and relaxation and, as a reflection of the past and present management, it is a part of our historical and cultural heritage.

Today forests cover about a third of Earth’s land surface. They affect the local, regional and global climate. They bind carbon dioxide, thus storing carbon and releasing oxygen. They retain excess water in case of storms and floods, purify the air and water and protect us from the wind. Their roots protect the soil against avalanches and erosion. Many drugs in modern medicine originate precisely from the plants of tropical forests. Forests contain about half of the organic carbon and more than three-quarters of all the living mass on Earth! More than three-quarters of the accessible water to humans come from forest river basins.

Treetops with leaves are factories in which trees produce organic matter and oxygen. In doing so, they use carbon dioxide from the atmosphere. Forests are the world’s largest depository of carbon, which the plants have taken from the air and processed into an organic matter. Healthy forests can respond to the increased amounts of carbon dioxide in the air by increasing the consumption of it and accelerating their growth!

Spruce forest (photo: U. Galien, archive ZRSVN).

Every part of a forest is a link in the food chain, including undergrowth, fallen leaves and dead wood. On fallen trunks, stumps and small wood residue live many species of fungi and mosses and in them, numerous small arthropods, earthworms and other animals that feed on dead wood, thus decomposing it. The dead wood is a set table for the birds that feed on these animals, and they also find or carve out cavities for their nests in large old trees. In the upper layer of soil, tiny animals, fungi and bacteria from the waste parts of plants and dead animals produce humus, which holds water and is a source of nutrients for plants. The fungi absorb a part of these nutrients and gradually pass them on to the plants; thereby they retain the nutrients so that they are not rinsed off by the precipitation.

Old forests and especially primary forests, in which there are numerous old and dead trees, are a treasure trove of biodiversity. The virgin forest hosts the species that cannot be found in a managed forest. Approximately 170 species protected by European directives due to endangerment are bound to forests. Due to the years of predominant sustainable forest management, Slovenian forests are renowned for their high biodiversity. Part of this diversity are also many species that have elsewhere in Europe already disappeared.

Beech forest (photo: U. Galien, archive ZRSVN).

The majority of forests are nowadays shaped by man with his management, with which the species composition changes and the biodiversity is often reduced. Throughout history, in the developed world, man thinned most of the lowland forests to acquire agricultural land; three-quarters of the forests in the temperate zone were thus already transformed into fields. The forest area in the world is drastically decreasing, mainly due to thinning. The forests in tropical regions are disappearing the fastest, with which their mitigating impact on the global climate is decreasing as well. In those areas, every year forests disappear from an area equal to the size of five to eight Slovenias. The largest recorded natural closed forests are found in the tropical part of South America, in Siberia, Southeast Asia, Canada and the mountainous parts of the USA. Significant, but already fragmented forest areas can also be found in Equatorial Africa and the Southern and Eastern Europe.

In some places, forests are grubbed up and plantations of tropical wood species are planted in the same place. These are by no means a substitute for a natural forest! Since they contain only one tree species, there are not many animal species to be found in them. Trees on plantations grow quickly, need more water and nutrients than natural vegetation, often require irrigation and excessively deplete the soil.

Lately, tropical forests are also thinned for new fields where “bio-propellants” are produced. Some studies have shown that more energy is used to produce biofuels than these fuels deliver. At the same time, we destroy the forest which would, without any energy or financial investment, reduce the amount of carbon dioxide in the atmosphere on its own.

Stag beetle (photo: S. Jenčič, archive ZRSVN).

Due to the thinning of forests, animal species are disappearing; those that live only in the old-growth forests are the first and the most endangered. Observations suggest that the world’s populations of forest animals have decreased by 60 percent since 1970. In the Northern and Southern Europe, even the populations of widespread forest bird species have decreased by a third in the last 30 years. More than half of the forest species, protected by European directives, are in a disadvantageous state.

Forest covers 60% of Slovenia and its area has been increasing in recent years. The reason lies in the overgrowing of abandoned agricultural land. Although the surface of the lowland forest has been gradually decreasing due to urbanization in Slovenia in the last decades, ,  the total area of the forest has slightly increased.

Rivers, streams, river floodplains, lakes as well as those water surfaces that are the work of man (puddles and ponds, navigable and drainage channels and water containers) are combined under the concept of inland waters. European fresh waters are home to about 250 species of vascular plants and 250 species of fish.

Thick shelled river mussel (photo: M. Rogelj, archive ZRSVN).

Only a few rivers and streams are still in the natural state today; water habitats are changing due to regulation, fragmentation, pollution and water abstraction. Biodiversity in these ecosystems has been gradually declining for at least a century and the consequence of this is also the decline of economically important species. Watercourses that were regulated or otherwise modified by man are increasingly transforming from the mitigators of natural disasters to the cause for them.

Inland waters in Slovenia – the total length of running waters in Slovenia is just under 27,000 km – are home to 93 species and subspecies of fish. In the clay banks and between the roots, the European crayfish is hiding and under the stones in the more lively streams lives the stone crayfish. In the sandy or silt bottom, we find water snails and mussels – Slovenia is one of the richest countries in the world with regards to them! The otters feed on these invertebrates, digging the lair in the earthy shore. Some types of insects – dayflies, caddisflies, stoneflies, dragonflies – spend most of their lives in water. Before an adult animal completes its life within a few days or months, it can remain in development as a larva at the bottom of a stream for several years. The riverbed with millions of animals and microorganisms absorbs and processes the organic matter, heavy metals and other chemical pollutants, which flow into the watercourses with wastewater. It thus purifies the water, while the aquatic plants enrich it with oxygen.

Kingfisher (photo: D. Klenovšek, archive ZRSVN).

Lakes, meandering rivers with natural banks and floodplains are natural high water retainers, which occur in heavy rains or at high river flows. The vegetation growing on the banks and in the surroundings, as well as the soil that is the product of plants and animals in the ecosystem contribute to water retention. They thus protect the places that lie downstream against floods and act as water collectors during the rainy part of the year and provide the supply during drought periods. Inland waters supply the groundwater, from which we get most of the water for daily use in Slovenia. Vegetation in natural watercourses prevent the transfer of gravel, sand and silt and reduce the depositing of large quantities of these deposits in the lower flows of the rivers and coastal ecosystems.

The roots of plants, especially of the trees growing on the banks, consolidate the banks and prevent the water from eroding them and carrying them away. The line of trees and shrubs along streams and rivers is a diverse habitat of birds, small mammals, amphibians and insects. We know that the importance of freshwater ecosystems for people’s lives is remarkable. From observations and data, we conclude that the consequence of the degradation of these ecosystems is a huge decline in ecosystem services.

For most aquatic animals, dams are an impenetrable boundary, which divides the river into two separate ecosystems and the species into two separate populations. The two smaller ecosystems that are created are more sensitive to environmental impacts than one large ecosystem and small populations also die out more quickly. Dams are in most cases the result of small and large hydroelectric power plants.

Otter (photo: T. H. Oršanič, archive ZRSVN).

Regulations reduce the living space of wildlife and plants, while the polluted water impairs the quality of the habitat that remains. Smooth concrete or stone-clad riverbed no longer offers a lot of hiding places for animals – snails, mussels, aquatic oligochaeta, crabs and shrimps, as well as the larvae of dragonflies, caddisflies, stoneflies and dayflies; even less so for mammals and birds. When the small animals disappear, the watercourse is no longer attractive to larger animals that feed on them. Where there is no life, the watercourse loses its self-cleaning ability. Many species of water birds are among the globally endangered and their number is declining more rapidly than with dry-land species.

In contaminated rivers and streams, there are fewer plant and animal species than in the clean ones. Between 1970 and 2000, the populations of freshwater organisms decreased by half – this decline in animal species is greater than in seas or on land. On the other hand, in many places the rare species that are resistant to pollution have unnaturally multiplied.

A special problem of relatively isolated ecosystems, such as inland waters, are non-native invasive species that can supplant indigenous species and thus significantly reduce biodiversity. Today, 296 non-native species of invertebrates and 136 non-native species of fish live in European inland waters. In our waters, there are 17 non-native species of fish and the banks of some streams and rivers are covered with non-native invasive plants: Canada goldenrod and giant goldenrod, Himalayan balsam and Japanese knotweed. Especially along the lowland watercourses, the compounds of these species have supplanted a variety of indigenous plant species, which are normally found next to waters.

Karst caves are a unique habitat due to the constant darkness, high humidity and living conditions that almost do not know the seasons. More than 12,000 caves are known in Slovenia, they are relatively well preserved and are renowned for their specially adapted animals. The Dinaric Karst is an absolute record holder in the world for its diversity of cave animals and the Postojna Cave system is the richest underground cave in the world with as many as 99 animal species!

Titanethes albus (photo: C. Mlinar, archive ZRSVN).

Man’s aggressive space management has so far spared the caves and due to their isolation and inaccessibility, they are relatively well preserved. However, lately they have been increasingly endangered by waste dumping and chemical and organic pollution of groundwater. In some locations, even the stealing of cave animals cannot be ignored, which is done by unauthorized researchers and collectors.

The Karst was created where the layers of calcareous shells of the dead single-celled animals, clams and corals in the sea piled up during the geological history, which make up today’s calcium carbonate deposits. The calcareous layers dissolve under the influence of precipitation, which is why the Karst world is corrugated and full of cracks and caves, ranging from microscopic size to the largest Karst caves.

The Karst world covers 5 to 10 percent of the land surface. The largest Karst landscapes are in China and Australia and important Karst areas can also be found in the USA, Mexico and the Andes. In Europe, most of the Karst phenomena can be found in the Alps, the Balkans, Slovakia and Ukraine. In Slovenia, Karst occupies 44 percent of the territory. Karst caves are scattered throughout most of Slovenia, except in the north-eastern part.

In addition to large caves, the cave habitat also includes crevices and cracks, which can be dry or filled with water. There are no plants in the untouched caves because there is no light. The food in the caves is therefore scarce, the diet of these animals in most cases consists only of the particles that the water brings from the surface. There are about 370 species of true cave animals in Slovenia. Slovenia has the richest array of cave animals in the world. In addition to the true cave species, the animals from the surface also stray into the Karst caves in order to find a temporary or permanent residence in them. Bats are common inhabitants of the caves.

Cave animals differ from their surface relatives in that they do not have skin colour and eyes and their legs and sensors are prolonged. In the watery parts of the caves, crustaceans whose size can be measured in millimetres and centimetres are predominant, while spiders, pseudoscorpions, centipedes, beetles, springtails and mites live in the dry parts of caves. Our cave world is especially renowned for the abundance of cave snails and there are many endemics among the cave animals. This means that many cave animals are known only from Slovenia and one sort of the cave amphipoda was found only in a single jet of water in the Planinska Cave!

Laemostenus schreibersi (photo: M. Pršina, archive ZRSVN).

We should not forget that a large part of drinking water in Slovenia comes from Karst aquifers. Water connections in the underground are widely branched and not fully known and therefore pollution from the surface can flow anywhere into the underground. Since the Karst world also has a very poor capacity of cleaning the water, the consequences of contaminated water may reach unpredictably far. The harmful substances are not only bad for us, but also for the tiny animals in the caves; the largest polluters of cave waters are nitrates and pesticides. Waste materials and particles in the contaminated water in modest cave conditions mean an additional source of food! What may seem helpful at first glance is not advantageous for cave animals. The food attracts animals from the surface, who are only occasionally looking for food here. The species from the surface are more aggressive and can supplant the modest cave species. The illumination of tourist caves has a similar negative impact on cave animals. Light enables the growth of algae, which again represent additional food.

Fun Facts


Did you know that not all bears go into their dens in the winter? It all depends on the food supply in the autumn (when the bear accumulates fat) and in the winter (when there is markedly less food). If a bear is accustomed to food sources close to humans (composts, garbage cans, wild landfills, meat from the slaughter), it will not go into hibernation but will be visiting a village.



Did you know that the roots of a tree extend beyond its treetop? In the forest, the roots of the trees touch and intertwine, protecting the forest ground from slipping and erosion.



Did you know that bark beetles are polygamists? The male hollows out a cubbyhole in the spruce tree and invites the females into it. Usually, 2 or 3 respond. After fertilisation, they each dig their own tunnel away from the cubbyhole and lay eggs in the walls of the tunnel.



Did you know that not all flowers have colourful blossoms? Along the Ajdovski zid wall, in the Kobilji curek stream and in Lanišče, we may observe a flowering henbane bell in April, which has black-purple, brown blossoms. The plant is poisonous.



Did you know that newts and fire-bellied toads have warning colours only on their bellies? In case of danger, a fire-bellied toad throws itself on the back, arches its garish belly and plays dead. Predators think the animal is dead and bloated, thus inedible.



Did you know that unroofed caves are created because their ceilings become thinner and then collapse? One day this will happen to the Postojna Cave and it will look like a cave by the Roman wall in Vrhnika.