Parameter Tree:
EARTH SCIENCE > BIOSPHERE > ECOSYSTEMS > TERRESTRIAL ECOSYSTEMS > ALPINE/TUNDRA

Definition:
Habitat found in the zone on mountain tops between permanent snow and the cold limits of trees, or in arctic regions, characterized by very low winter temperatures, short cool summers, permafrost below a surface layer subject to summer melt, short growing season, and low precipitation.

Reference:
The Nature Conservancy