Nature on our doorsteps: Barking up the right tree . . .
Rosaleen Dwyer is the County Heritage Officer at South Dublin County Council – every week she gives us an insight into nature on our doorsteps and the beautiful biodiversity of its plants and wildlife.
In many ways, the bark of a tree does the same thing for trees as our skin does for us. It protects the important tissues underneath that help the individual to grow and stay healthy.
Bark consists of the tough outer layers of tissue on the trunk and branches of a tree. Underneath the bark, there are different layers of living cells that transport water and food up and down throughout the woody tree. If these cells are damaged, the passage of food and water can become blocked. This can affect the tree’s survival.
Bark therefore acts as a very important protective layer for the inner workings of the tree.
It prevents the living cells from drying out in hot or windy weather, while also protecting them from freezing frosts. The bark of some tree species also tastes unpleasant to insects and grazing mammals. While this may not prevent all attempts at nibbling or grazing, it can help reduce damage from creatures that wish to feed on the tree’s sugary sap.
Tree bark offers a place for mosses and lichens to colonise and grow
Different tree species have different types and textures of bark. Trees like the London Plane have bark that naturally peels off in layers and drops away. This helps these trees adapt and survive in cities where air quality is poor, because the dust and harmful pollutants that collect on the bark are regularly discarded by the tree.
Protection is not the only benefit that bark provides.
Many mosses and lichens use bark as a very useful platform on which to grow, while insects and spiders make their homes in the deep cracks and crevices of old bark. These creatures are hunted out by birds and other insect predators, while some bat species may also roost overnight underneath the loose bark of old trees.
The bark of a single mature tree therefore does incredible work, not just for the tree but for biodiversity in general.
