The tundra is characterized by permafrost, a layer of permanently frozen subsoil. During the short cool summer, the ground thaws to a depth of a few centimeters and becomes soggy. In winter, the top layer of soil freezes again. This cycle of thawing and freezing, which rips and crushes plant roots, is one reason that tundra plants are small and stunted. Cold temperatures, high winds, a short growing season, and humus-poor soils also limit plant height.
Abiotic factors strong winds; low precipitation; short and soggy summers; long, cold, dark winters; poorly developed soils; permafrost
Biotic factors
Plant life: By hugging the ground, mosses and other low-growing plants avoid damage from frequent strong winds. Seed dispersal by wind is common. Many plants have adaptated to growth in poor soil. Legumes, for example, have nitrogen-fixing bacteria on their roots.
Animal life: Many animals migrate to avoid long harsh winters. Animals that live in the tundra year-round display adaptations, among them natural antifreeze, small extremities that limit heat loss, and a varied diet.
Which Biome?
An ecologist collected climate data from two locations. The graph shows the monthly average temperatures in the two locations. The total yearly precipitation in Location A is 273 cm. In Location B, the total yearly precipitation is 11 cm.
Interpret Graphs What variable is plotted on the horizontal axis? On the vertical axis?
Interpret Graphs How would you describe the temperature over the course of the year in Location A? In Location B?
Draw Conclusions In which biome would you expect to find each location, given the precipitation and temperature data? Explain your answer.
Analyze Data Look up the average monthly temperature last year in the city you live in. Plot the data. Then look up the monthly rainfall for your city, and plot those data. Based on your results, which biome do you live in? Did the data predict the biome correctly?