The moor birch;
The Fondation Hëllef fir d’Natur has announced that the Tree of the Year 2023, the moor birch (Moorbirke), is mainly found in swamps/bogs; it is the only European tree species that grows on nutrient-poor, permanently wet moorland / marshy soils.
Like the closely-related hanging birch (Hängebirke), the moor birch is a pioneer species of raw soil. The two birch species produce countless small winged seeds which are dispersed by the wind, to finally germinate wherever light is sufficient and the absence of competing vegetation allows them. The moor birch clearly colonises most of our humid areas / wetlands.
For this reason, the location is quite helpful in distinguishing between hanging and moor birch. The leaves are often found very high in the tree, and it is only on the old specimens of moor birch that the white- and black-ringed bark takes on more and more the fissured structure and the typical grey colour. The leaves have a clear distinguishing feature: they are diamond-shaped in the hanging birch and rather heart-shaped in the moor birch. The young leaves and shoots of the moor birch are covered with a fine down, which explains the Latin name of the species "pubescens".
It is of little help that where both types of trees occur, as hybrids with intermediate characteristics are not uncommon.
Botanically, the moor birch belongs to the hazel family, which can be seen in the shape of the flowers and seed pods in typical hanging catkins.
Due to the drying of peat bogs, birch swamp forests are a rare European habitat, protected as a priority by the FFH directive. In Luxembourg, the typical swamp sites have largely disappeared due to drainage and subsequent reforestation.
The names of the wetlands that remain give information about the water content of the site: Conzefenn, Koufenn, Fooschtbach, Sporbach, Elteschmuer, ...
Most of these locations are found in the Oesling, where higher rainfall, cooler climate and drainless valleys have favoured the formation of bogs. Both in Conzefenn and in Elteschmuer, measures are being put in place to preserve the moor birch forests as habitat, but this has been made difficult by the extreme dryness of recent years.
