Veteranisation of young trees in order to enhance green infrastructure of valuable trees
About this good practice
Old broadleaved trees are a very species rich habitat. Up to 1000 species are depending on specific micro structures that only occurs in trees that are 250 ears or older such as holes, cavities, dead branches and sap flows. Today 18% of wood-living beetles are threatened in Europe and there is an acute need for more of these habitats.
In many places there are old trees that host many species, but there is an age gap to the next generation. There are often few middle-aged trees. Thereby these important tree structures face a risk of disappearing in the landscape before new ones can evolve. This will in the end cause many species to disappear. By artificially creating the structures in younger trees, the species have a chance to survive.
Veteranisation is usually carried out by arborists and aim to create the structures naturally created by storm, lightning, grazing animals and woodpeckers. This will result in a premature aging of the trees making them a more suitable habitat for many species depending on old trees, such as lichens, mosses, bats, fungi, mammals, and birds.
The practice should be carried out on trees approx. 25-40 cm in diameter of the same species as the old trees in the area.
This method allows us, within a relatively short period of time, to improve the conditions for species dependent on structures normally only found on old trees. With this method, we can both bridge geographical distances in the landscape as well as the generation gap.
Resources needed
Two skilled climbing arborists can veteranisate 5-10 trees in a day depending on skill, which habitat in the tree they create and the accessibility of the area.
It is important to plan wich trees to veteranise in advance. This requires a good inventory of the trees in the surrounding landscape.
Evidence of success
Monitoring has shown that veteranisation is successful in mimicking naturally formed features and creating useful habitats for a variety of species faster than would have occurred naturally. This is indicated by the presence of decay and a higher number of birds, bats, and threatened beatles etc. in veteranised trees than in similar other trees in same area.
Potential for learning or transfer
The problem of a generation gap (lack of suitable successors) to old trees is probably common around Europe. This increases the probability of extinction for species depending on structures in old trees. Veteranisation can be used by different stakeholders and be applied in different regions or countries. It is a relatively cheap method.
This good practice is therefore considered to have a high learning and transfer potential.
In areas with many young trees, this good practice can help the species survive until enough trees have become old.