- biome characterized by permafrost, minimal tree growth, and extreme cold
- two types: arctic tundra (high latitude) and alpine tundra (high altitude)
- short growing season of 50-60 days limits vegetation to mosses, lichens, grasses, and dwarf shrubs
- permafrost layer stores massive quantities of frozen carbon cycle reserves
- thawing permafrost releases methane and CO2, creating a climate feedback loop
- fragile ecology: slow recovery from disturbance due to extreme conditions
- supports migratory species: caribou, arctic foxes, snowy owls, millions of nesting birds
- soil is thin, waterlogged in summer, and nutrient-poor
- alpine tundra occurs above treeline on every continent with mountains
- acts as a sensitive indicator of planetary warming trends
- covers ~10% of Earth’s land surface