Above the latitudinal treeline

Arctic tundra, as high-latitude tundra, is located in the northern hemisphere, encircling the north pole and extending south to the coniferous forests of the taiga or boreal forest, and the Arctic is known for its cold, desert-like conditions. [NPS Arctic] There are two types of tundra, the same page says: arctic tundra is above latitudinal treeline and alpine tundra is above elevational treeline. [NPS Arctic] Lake Clark National Park and Preserve says there are two kinds of tundra in Alaska, alpine and arctic: Arctic tundra is found north of the permafrost line, generally north of the arctic circle, and alpine tundra is found around the state at high elevations — the kind found in that park. [NPS Lake Clark] The National Natural Landmarks tundra page says alpine tundra are found at high elevation on mountaintops, whereas arctic tundra are located on high-latitude landmasses above the Arctic Circle or in far southern reaches like Antarctica. [NPS landmarks]

One Park Service page places Arctic tundra above the latitudinal treeline. Lake Clark’s page says north of the permafrost line, generally north of the Arctic Circle. The landmarks page says high-latitude landmasses above the Arctic Circle, or far southern reaches such as Antarctica. Those lines are related, and they are not identical.

A single caribou walks across a green, low, treeless coastal plain under a wide sky — A caribou on the coastal-plain tundra of Arctic National Wildlife Refuge, Alaska, photographed by Lisa Hupp of the U.S. Fish and Wildlife Service on 28 June 2021. This is Arctic tundra, not alpine tundra in the Rockies.Lisa Hupp, U.S. Fish and Wildlife Service · Public Domain (USFWS)

For Arctic tundra, the Park Service says the growing season ranges from just 50 to 60 days. [NPS Arctic] Arctic tundra is underlain by a layer of permanently frozen soil called permafrost, which is permanently frozen ground that affects nearly everything in the Arctic ecosystem, including soils, vegetation, water, and wildlife. [NPS Arctic] During summer months, the top layer of soil thaws — known as the active layer — creating a wet landscape with rapid runoff. [NPS Arctic]

An aerial view of a snowy tundra landscape marked by a tight network of polygonal cracks and ponds — An aerial view of ice-wedge polygons on the tundra at Cape Krusenstern National Monument, in the Western Arctic National Parklands of northwest Alaska, photographed on 31 January 2013. This is Arctic patterned ground, not alpine tundra in the Rockies.National Park Service · Public Domain (NPS)

Low, rolling Arctic tundra with polygonal patterning and several distinct rounded mounds under a cloudy sky — Tundra polygons and pingos — the hill-like mounds formed with water and permafrost — in Bering Land Bridge National Preserve, Alaska, photographed on 12 August 2007. This is Arctic tundra on the Bering Land Bridge, not alpine tundra in the Rockies.Bering Land Bridge National Preserve, National Park Service · CC BY 2.0

The polygons and pingos are Arctic landforms, seen from Alaska, not a picture of the Colorado alpine. For the comparison with high mountains, open the year-wheel desk.

Above the latitudinal treeline

Sources on this page