Food webs of the tundra are limited due to lack of sunshine. The start of any food web is sunshine and for many months of the year there is little to no sun shining on the tundra, which becomes a frozen desert. When the spring thaw bursts forth, a simple tundra food web quickly begins production. Plants are devoured by herbivores and carnivores eat the animals that have eaten the plants.
Typical Food Web
When light and temperature conditions of the tundra permit, plant growth begins. Typical plant growth of the tundra includes low growing perennial shrubs and grasses, mosses, and lichens.
Vegetation leads to invertebrate grazers such as grasshoppers, caterpillars and other leaf eating bugs. The increased number of insects draws predatory invertebrates like spiders and carnivorous beetles.
The increased activity of the tundra food web draws larger vertebrates such as birds and grazing animals. Tundra birds maybe year round residents, such as the rock ptarmigan, or migratory from southern regions, like sandpipers and plovers. Caribou herds move into grazing grounds. Ducks and geese arrive and feed on the vegetation. Small mammals such as lemmings take the increased food supply as a sign to begin the breeding cycle.
The increased numbers of vertebrates provide a food supply for carnivores. Predatory birds such as owls and gyrfalcons hunt other birds and small mammals over the open tundra.
Lemmings and wading birds draw carnivores such as Arctic foxes and jaegers. Wolves hunt large grazing animals such as the caribou. If predators themselves avoid being eaten upon death, their bodies will decompose and become part of the earth.
The entire time the tundra food web is expanding, microbes are at work in the soil.
All dead plant and animal remains, and excreted material are consumed by decomposers such as earthworms and turned into soil. In turn the soil will provide the energy for new plant growth and the cycle of the food web on the tundra will begin again.
The limited sun for photosynthesis of the polar tundra means growth of green plants is small compared to a more fertile eco-system such as the rainforest. Tundra vegetation goes dormant during the long and harsh winter.
When vegetation can’t survive, the tundra food web also draws to a halt. An eco-system with low production of plants can only support limited animal life and will have a poor bio-diversity. Only highly adapted plant and animal species can survive on the tundra.
Everything living, plant or animal, must leave or go dormant to survive the harshest part of the winter and all activity except for bitter howling wind stops. During this period even the lowest microbes must cease production and everything on the tundra including the food web freezes.
This short growing season of the tundra and lack of bio-diversity has lead to highly adapted and efficient food webs. From soil to plant to animal, a simple food web survives the harsh environment of the tundra.
Wikimedia Commons: Tundra by Ranveig, 2004, Arctic Wolf by A.I., 2007.
Moore, Peter D. Tundra: Biomes of the Earth. Chelsea House, 2006.