Reindeer Lichen

Reindeer lichen is a pale, branching lichen found across the tundra and boreal forest regions of the Northern Hemisphere, including large parts of the Arctic, forming extensive mats or cushions on the ground that can dominate the vegetation across vast stretches of otherwise sparse northern landscape. Despite its plant-like appearance, it is not a plant at all but a composite organism formed from a symbiotic partnership between a fungus, which provides structure and absorbs water and minerals, and an alga, which contributes food through photosynthesis. Reindeer lichen grows extremely slowly, sometimes only a few millimetres a year, and it forms an essential winter food source for caribou and reindeer, which can smell it through snow cover and use hooves to dig down and expose it during the coldest months when little other vegetation is available. Because it recovers so slowly once disturbed, heavily grazed or burned patches of reindeer lichen can take decades to fully regenerate, making it an important indicator of the long-term health of Arctic and subarctic ecosystems.