Tree lichen: what to do about lichen on trees?

When lichens are first spotted on a tree, there is usually great concern that they are harming the tree in some way. Read here whether tree lichen needs to be removed.

Recognize tree lichens

Although there are lichens on trees of different colors, they are all so similar that it is difficult to confuse them with anything else. They are usually green, yellow-green, or blue-gray-green. Lichen is not an independent plant, but a community, which cannot be seen with the naked eye.

Note: Lichen can get very old. 100 years and more are not uncommon.

A fungus forms the basis of the lichen, it adheres to the subsurface, ensures stability and supplies the community with water and minerals. The alga or cyanobacteria cling to the fungus, it benefits from its water uptake and photosynthesis takes place in the community.

Common types of lichen

• Real plum lichen (Evernia prunastri), preference for sloes and plum trees
• Common yellow lichen (Xanthotia parietina) on bark and rocks in agricultural areas
• Key lichen (Parmelia), the last type of lichen in areas with high levels of air pollution
• Lichen (Graphis scripta) on linden, mountain ash or hazelnut

Differences from mushrooms

right one Tree fungi do not just stick to the tree, their root network penetrates the wood and destroys it. In addition, many fungi are putrefactive agents, so they are actually harmful. Only the fruiting body is visible, which has different colors depending on the type of mushroom, but rarely green. Tree fungi are often very hard and difficult to remove from the substrate; the fruiting bodies are often much larger and, above all, thicker than lichens.

Lichen on trees

Since tree lichens seem particularly fond of colonizing older, weakened trees, they are considered pests. This assumption is wrong, however, as they do not penetrate the tree and therefore neither deprive it of nutrients nor cause any damage. Some lichens can settle better on weakened trees because they have fewer antibodies in the bark. Since lichens occur more frequently in locations that they are comfortable with, they can literally overgrow the corresponding trees. This is particularly noticeable in winter, when the leaves of the tree are missing.

Remove lichen

Tree lichen must not and should not be removed, especially not for purely aesthetic reasons. Some species of lichens have become rare due to pollution and require every habitat they can find. There is also protected species.

One reason for removal is general trunk maintenance, in which loose pieces of bark are loosened from the tree so that pests cannot nest underneath. A stiff brush is usually sufficient for this.

Note: Lichen even protects trees as they prevent them from being in place on the bark Colonize harmful organisms.

Tree lichen and air quality

Lichen is an indicator of air quality because it can only absorb its nutrients from the air. The better the air, the more diverse the lichen species that can be found in an area. Conversely, this means that lichen is completely absent in locations with very poor air quality.

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