Which of the following is a key feature of the tundra biome?

A key feature of the tundra biome is permafrost, which is a layer of permanently frozen soil that lies beneath the surface. This unique characteristic significantly influences the ecosystem of the tundra. Permafrost restricts the types of vegetation that can grow, as the soil above it thaws only during the short summer season, allowing for limited plant growth, primarily mosses, lichens, and some hardy grasses and shrubs.

The presence of permafrost also impacts the animals that inhabit the tundra, as they must adapt to the harsh conditions and the limited availability of food. This biome is often found in polar regions, where temperatures remain low for most of the year, leading to a distinctive environment that is quite different from other biomes like deserts or forests.

This contrasts with desert-like conditions, which are characterized by dry environments but do not typically include permafrost, and with sandy soil and dense forests, neither of which accurately depict the tundra's composition or vegetation. Understanding permafrost is crucial in recognizing the ecological dynamics and challenges that define the tundra biome.