Figure 1. Dall’s sheep feeding on lichens in Alaska. [Source Photo National Park Service, Alaska (Public domain)]Many animals feed on lichens. [1] For example, the abundant lichen vegetation of the tundra at high latitude provides a food source for reindeer and caribou and – occasionally – for some domestic animals (Figure 1). Cladonia are especially appreciated. Although called “reindeer lichens”, Cladonia rangiferina and Cladonia arbuscula, which are too bitter, are generally avoided in favour of other species such as Cladonia stellaris (Figure 2). Due to their importance in reindeer feeding, lichens play a major role in the food chain. It should be noted that after consumption of lichens by a reindeer herd, the growth of lichens being very slow, the reconstitution of lichen vegetation requires a duration of more than 30 years in the pasture. In mountain environments, it is the chamois and ibexes that readily graze on the Cladonia on the ground and sometimes on the branches or trunks.
Due to their importance in reindeer feeding, lichens play a major role in the food chain. It should be noted that after consumption of lichens by a reindeer herd, the growth of lichens being very slow, the reconstitution of lichen vegetation requires a duration of more than 30 years in the pasture. In mountain environments, it is the chamois and ibexes that readily graze on the Cladonia on the ground and sometimes on the branches or trunks.
In high mountains, the deposition of bird droppings favours the development of certain so-called nitrophilous species that seek nitrogenous materials, such as Xanthoria elegans, X. calcicola (Figure 4). In the Hautes-Alpes (France), the proliferation of these lichens on some walls has made it possible to detect the presence of golden eagles. [3] Birds often forage for food (spiders, insects or eggs or larvae) under lichens.
[1] Lichens are not widely consumed by humans because they are tough, much less tasty than mushrooms and even sometimes bitter. However, in times of famine, Canadians in the Far North ate various species of Umbilicaria (including Umbilicaria pustulata), known as “rock guts”, which are still consumed in Japan, cooked in fat, or raw, in salads. Even today, Iranian farmers still use Cetraria islandica to make flour and bread sold under the name “shirsad”.
[2] Boch, S., Prati, D., Werth, S., Rüetschi, J. & Fischer, M. 2011 – Lichen endozoochory by snails. Plos One, 6(4): e18770.
[3] Rémy, C. 2006 – Quelques relations entre lichens et oiseaux. Bull. Inf. Ass. Fr. Lichén. 31, 2, 2.32-35