Reindeer moss (Cladonia rangiferina) is a type of lichen, not a true moss. It forms a symbiotic relationship between a fungus and an alga or cyanobacterium, where the fungus provides structure and protection, and the alga or cyanobacterium produces food through photosynthesis. This organism has a distinctive spongy, foamy, grey-green appearance, resembling miniature trees or coral with many branches. It grows in cushion-like patches up to 10 centimeters tall, though its growth rate is notably slow.
Global Presence
Reindeer moss is widely distributed across the globe, primarily found in cold, northern climates. Its distribution is circumpolar, meaning it occurs across high latitudes around the North Pole. It thrives in biomes such as the Arctic tundra and boreal (taiga) forests.
In North America, it covers large areas of the ground in the Arctic tundra regions of Canada and Alaska. The lichen is also common in Europe, spanning from the Scandinavian countries through the boreal forests of Russia. Its presence extends to Asia, particularly in the Siberian tundra and boreal forests. Reindeer moss can also be found in pine heaths and open areas of the forest floor within these regions.
Environmental Needs
Reindeer moss prefers specific environmental conditions. It grows on well-drained, nutrient-poor, and acidic substrates such as sandy or rocky soils and peaty areas. It can also establish itself on organic materials like conifer needles, woody debris, or dead moss. This lichen shows a high tolerance for cold temperatures and freezing conditions.
While it tolerates cold, reindeer moss relies on humidity and atmospheric moisture for its water needs rather than direct soil moisture, as it does not have roots. It can absorb moisture and nutrients directly from the air through cells on its surface. While it can tolerate some shade, it prefers open, sun-exposed habitats. Its slow growth rate, around 3 to 11 millimeters per year, means it can take decades for mats to fully develop or recover from disturbance.
Role in Ecosystems
Reindeer moss plays an important role within its ecosystems, particularly as a food source. It is a primary winter food for reindeer and caribou. These animals have specialized digestive systems that allow them to extract nutrients from this lichen, which provides carbohydrates for energy.
Beyond providing food, reindeer moss contributes to soil stabilization by anchoring the ground and preventing erosion, especially in areas with unstable permafrost. Its dense mats also help create microhabitats, offering shelter and food for smaller organisms like insects and spiders. The lichen also helps regulate soil temperature and moisture. Its slow growth and direct absorption of atmospheric elements make reindeer moss sensitive to pollution and environmental disturbances.