Fungi

Fungi of the Northern Velebit National Park

Fungi belong to some of the least explored groups of organisms in Croatia and it is believed that as yet only 20 percent of species have been identified. This may be surprising, given the popularity of mushroom picking! However, fungi with large fruiting bodies (scientific name: macromycetes) constitute only 20% of the fungal kingdom. Namely, what most people think to be a “mushroom” is only its smaller top part that serves for reproduction. The main mushroom body consists of a shapeless web of filamentous cells – the hyphae which grow through their meal – a layer of dry leaves, trees, dead animals, dung or other organic matter. Occasionally, fungus sprouts a special surface structure where spores serving for propagation are produced. These fruiting bodies or sporocarps, are what most people think to be a mushroom.
In addition to the familiar form of fruiting body, consisting of a stem and a cap, there are also plate-like, coral-shaped and other unusual forms of fruiting body, with a very large number of fungi producing quite small fruiting bodies of various shapes, some smaller than a millimetre. Often they can only be seen with the help of a microscope or magnifying glass.

Fungi are very important members of the ecosystem. They act as decomposers (saprotrophes) and return nutrients into circulation. In addition, many fungi live in mycorrhiza – a symbiotic association with woody plants, in which the fungus provides the plant with access to water, minerals and other important compounds, while the plant feeds the fungus with nourishing organic matter. Symbiotic fungi protect their hosts from a variety of disease-causing parasites, predators and competitors. In the forest, many trees live in such a symbiosis, with fungi significantly contributing to better health and growth of trees!

In current studies (by the end of 2011), as many as 382 species of fungi have been identified within the Park area. Many of them are rare and endangered, because they depend on deadwood that is scarce in managed forests. The trees in national parks are not felled and the forest is left to natural processes, which is why it abounds in bulky wood remains of dying old trees that are inhabited by a very large number of saprotrophic fungi generally not found in managed forests. Diseased and old trees remain in the forest, where they become food and home to fungi and numerous other living organisms.
National parks also provide an ideal habitat for parasitic fungi that live on trees causing disease or attacking already weakened or diseased trees. In a managed forest, such trees are removed from the forest together with their fungal tenants. Although disease is generally considered as something bad, it is an essential part of the dynamics of life and survival and in a healthy ecosystem contributes to biodiversity and stability of the ecosystem as a whole.