The transfer of energy from organism to organism forms a food chain. All the possible feeding relationships that exist in a biome make up its food web. In the tundra, as elsewhere, the food web consists of producers, consumers, and decomposers. An analysis of the food web shows how energy is transferred within the tundra.

Green plants are the primary producers in the tundra. They produce organic materials from inorganic chemicals and outside sources of energy, like the Sun. Tundra annuals and hardy perennials, such as buttercups and dwarf willows, turn the Sun's energy into plant matter through photosynthesis.

Animals are consumers. Plant-eating animals, such as certain insects, caribou, reindeer, mountain goats, pikas, marmots, waterfowl, and lemmings, are primary consumers in the tundra food web. These animals then become food for the secondary consumers, which include predators such as spiders, wolves, and foxes. Tertiary...