Biotic factors in the Arctic tundra, as with other ecosystems, include living organisms, such as microorganisms, plants and animals. The biotic factors of the tundra include over 1,500 species of plants, which classify as mosses, lichen and grasses. The hardy group of animals calling the tundra home includes many types of mammals and birds, including polar bears, Arctic foxes, caribou and other iconic species.
The Arctic tundra experiences long, dark winters and faces some of the coldest temperatures on Earth. Whether transient visitors or year-round residents, the plants and animals of the tundra have special features for surviving the frigid Arctic air. Only plants with shallow root systems, which excludes all tree species, survive in these harsh conditions.
The thick layers of permanent frost beneath the surface of the Earth, called permafrost, prevent taller trees and plants with deeper root systems from growing. Shallow-root plants, which includes mosses, lichen and low-lying shrubs, grow close together. They endure the Arctic climate by carrying out photosynthesis in cold temperatures, growing low to the ground and blooming quickly in the summer. Arctic mammals, like the Arctic fox, have special adaptations too. These foxes have short ears and round bodies, covered with thick layers of fur, which insulates foxes from the cold. These biotic factors have a harmonious relationship with abiotic factors, such as climate and geography. In the aggregate, these factors form biomes.