Biomes

Tundra

Very cold, permafrost, treeless
947 Animals
1/40 Page
Overview

Understanding This Category

Tundra is a cold-climate terrestrial biome defined by low mean temperatures, a short growing season, and vegetation constrained by limited heat and, in many regions, perennially frozen ground (permafrost). It occurs primarily at high latitudes and/or high elevations where tree growth is inhibited by climatic and soil thermal conditions.

The tundra is a land of extremes: long dark winters, short summers, and strong winds. Much ground is frozen by permafrost; only a thin active layer thaws, creating dry gravel and wetlands. Few trees grow; low plants like mosses, lichens, sedges, grasses, and dwarf shrubs grow in long daylight, fueling insect booms and animals like caribou, arctic foxes, lemmings, and migratory birds. Permafrost stores much carbon and makes polygonal ground and hummocks. Warming can change thaw, water, plants, and carbon.

Key Characteristics

Low temperatures and long winters with a short, cool growing season
Tree growth limited, resulting in open, treeless or nearly treeless landscapes
Permafrost common in arctic forms, with a seasonally thawed active layer that restricts rooting depth and drainage
Vegetation dominated by mosses, lichens, sedges/grasses, and dwarf shrubs adapted to cold and wind exposure
Strong seasonality in productivity and wildlife dynamics, including migration, dormancy, and synchronized breeding
Slow decomposition and nutrient cycling, with cold soils storing substantial organic carbon and supporting distinctive freeze-thaw landforms
Climate

Climate Conditions

Tundra has long, cold winters and short, cool summers with strong winds and weak sun. Widespread permafrost keeps soils cold, shallow, and often waterlogged when the active layer thaws. Rain and snow are low but so is drying, so summer surface moisture can be high. Low heat and short growing seasons prevent trees and favor low, cold-tolerant plants.

Temperature

Very large: typically ~30-50°C (54-90°F) difference between mean winter lows and mean summer highs, often larger inland/continental tundra.

Average High
Summer average highs commonly ~5-12°C (41-54°F); winter average highs often ~-20 to -5°C (-4 to 23°F), depending on latitude and continentality.
Average Low
Summer average lows commonly ~0-5°C (32-41°F); winter average lows often ~-30 to -15°C (-22 to 5°F).
Extremes
Cold extremes can drop to ~-50°C (-58°F) in continental/arctic interiors; warm extremes may reach ~15-25°C (59-77°F) during brief summer heat events, especially in inland tundra.

Precipitation

Low: typically ~150-400 mm/year (6-16 in), much of it as snow; some coastal tundra can be slightly wetter.

Pattern
Often summer-peaking due to light rain/drizzle and convective showers; winter precipitation is generally light but accumulates as persistent snowpack. Meltwater pulses occur during spring/early summer thaw.
Humidity
Generally low absolute humidity (cold air holds little moisture), but relative humidity and near-surface wetness can be moderate to high in summer because evaporation is limited and drainage is restricted by permafrost.
Seasonality

Tundra has extreme seasons: a long cold, dark winter when most life is quiet, and a short summer with almost constant daylight and fast, brief growth. Snow cover, spring melt timing, and the active layer depth control water, nutrients, and plant timing. Short summers favor quick flowering, migrant wildlife and insect bursts; harsh winters and wind keep it treeless.

Growing Season

The tundra growing season is very short—about 6–10 weeks (45–75 days). In the coldest high Arctic it can be only 3–6 weeks. Peak growth is usually mid/late June through July, tied to snowmelt and long daylight.

Seasons

Seasonal Changes

Polar Night / Deep Winter

Late fall through mid-winter (varies by latitude; longest and darkest period at high Arctic sites)

Extremely cold; persistent snow cover; strong winds and frequent blowing snow; very low humidity; rivers/lakes largely frozen; permafrost fully locked; minimal liquid water availability; occasional mid-winter warm intrusions can create crusted snow/ice layers.

Primary production near-zero; plants remain dormant under snow; nutrient cycling slows; most energy flow relies on stored biomass, detritus, and marine subsidies (near coasts). Snow depth and wind redistribution create patchy insulation that influences survival of overwintering plants and small mammals.

Migration of many birds completed; only resident species remain (e.g., some ptarmigan, ravens) Mammals increase insulation (thicker coats, fat reserves); reduced activity to conserve energy Small mammals (lemmings/voles) use subnivean (under-snow) tunnels for warmth and foraging; predation dynamics depend on snow structure Predators (arctic fox, wolves, owls where present) track prey and exploit wind-scoured hunting areas Reindeer/caribou may use windswept ridges to access lichens; deep snow increases energetic costs and can cause winter mortality events

Late Winter / Return of Light

Late winter to early spring (increasing daylight after winter solstice; still below-freezing)

Cold persists but solar radiation increases; stronger temperature gradients in snowpack; surface hoar and ice-crust formation possible; daylight length rapidly increases with latitude; storms remain common.

Light availability increases without immediate plant growth; snowpack metamorphosis affects insulation and access to forage; early-season photoperiod cues initiate hormonal changes in animals (breeding readiness, molt).

Resident birds begin territory establishment and pairing as light returns Predators shift hunting strategies with changing snow hardness (crusts can aid or hinder pursuit) Ungulates adjust movement to balance forage access and snow conditions; some begin pre-migration staging Arctic foxes and other mammals begin den selection/maintenance in preparation for breeding

Spring Thaw / Melt Season (Shoulder Season)

Spring to early summer onset (short but intense; timing highly variable year-to-year)

Rapid warming; snowmelt and break-up of ice; intermittent freeze-thaw cycles; widespread surface water and flooding due to impermeable permafrost; formation of melt ponds; soils remain frozen at depth with a shallow, gradually deepening active layer.

Pulse of nutrient and organic matter transport with meltwater; strong microbial activity surge as soils wet and warm; brief but intense availability of fresh plant growth; high risk of erosion and thermokarst where ground ice melts.

Major influx of migratory birds timed to snowmelt and insect emergence; rapid nesting initiation Caribou/reindeer and other ungulates migrate to calving grounds, often synchronized with green-up Lemmings and other small mammals increase reproduction as conditions improve; predators respond numerically/behaviorally Increased scavenging opportunities during ice break-up and flood events; aquatic and coastal food webs become more accessible

Brief Summer / Growing Season

Early to mid/late summer (often only 6-10+ weeks of effective growth; longer in subarctic tundra, shorter in high Arctic)

Cool but above-freezing periods; long days to continuous daylight at high latitudes; active layer reaches maximum depth; soils often saturated and poorly drained; high insect abundance; episodic warm spells; fog common in coastal tundra.

Peak primary production concentrated in a short window; rapid plant growth, flowering, and seed set; high photosynthetic rates driven by long photoperiod; intense decomposition and nutrient cycling in the active layer; carbon balance can shift (CO2 uptake vs methane emissions from wetlands) depending on moisture and temperature.

Explosive breeding season for birds; nesting, chick rearing, and fledging occur quickly Mosquitoes/blackflies emerge in large numbers, altering ungulate movements (seeking wind, snow patches, or coastal breezes) Herbivores intensively forage to rebuild fat reserves; lactation in ungulates; rapid juvenile growth Predators exploit high prey availability (eggs, chicks, small mammals); some species cache food Molt in many birds and mammals; increased activity and dispersal of juveniles

Autumn Cooling / Freeze-up (Shoulder Season)

Late summer to fall (often rapid; first frosts can occur even during late summer in high Arctic)

Temperatures drop; first snowfalls; increasing storm frequency; daylight shortens quickly; freeze-up of wetlands and shallow waters; refreezing of the active layer begins from the surface downward; vegetation senesces.

Abrupt end to growth; plant tissues lignify and enter dormancy; nutrient resorption in plants; decomposition slows as soils refreeze; freeze-up stabilizes ground and reduces surface water connectivity.

Southward migration of most birds; staging in coastal and wetland areas Ungulates shift to winter ranges; increased foraging on shrubs/lichens as green biomass declines Predators follow prey movements; caching behavior increases in some species Coat changes begin/complete (winter pelage) and fat accumulation peaks; activity patterns shift to conserve energy

Day Length: Day length varies extremely with latitude: near the Arctic Circle (~66.5°N) summers have very long days and winters have very short days; farther poleward, continuous daylight (midnight sun) can last weeks to months, and continuous darkness (polar night) can also persist for extended periods. Ecological significance: photoperiod is a primary, reliable seasonal cue in tundra-often more predictable than temperature-synchronizing plant phenology (rapid growth/flowering during long-day conditions), timing of migration and breeding in birds, molting and coat-color changes in mammals, and the brief scheduling of reproduction and fat accumulation needed to survive the long winter.

Where Found

Global Distribution

Tundra occurs mainly as a broad, near-continuous belt around the Arctic Ocean (Arctic tundra) and, secondarily, as "alpine tundra" above the climatic treeline on high mountains and plateaus worldwide. Its distribution is controlled by persistently low temperatures, short growing seasons, and (in the Arctic) widespread permafrost; in mountains it is controlled primarily by temperature and exposure rather than latitude.

~1.5-2.0% of Earth's surface (approximate) of Earth's Surface
~8-10 million km² (global; Arctic + alpine tundra combined, approximate) Total Area

Notable Locations

Alaska North Slope (e.g., Barrow region) Canadian Arctic Archipelago (e.g., Ellesmere and Baffin Islands) Svalbard (Norway) Lapland (northern Fennoscandia) Yamal and Taymyr Peninsulas (Russia) Chukotka (Far East Russia) Icelandic Highlands (tundra/heath mosaics) Greenland coastal tundra (e.g., west coast near Nuuk and Disko Bay) Tibetan Plateau alpine steppe-tundra zones Rocky Mountain alpine tundra (e.g., Trail Ridge Road area, Colorado) Andean moorland (e.g., Ecuador and Colombia highlands) South Georgia Island (subantarctic tundra-like vegetation)
Conservation

Conservation Status

Globally threatened by rapid climate-driven change; while large areas remain, tundra ecological integrity is declining quickly due to warming, permafrost thaw, altered hydrology, and expanding industrial activity in parts of the Arctic.

Rapidly Declining Trend
Not primarily area-loss everywhere; instead rapid functional loss. In heavily developed Arctic regions, localized conversion/fragmentation can exceed ~0.5-1% per decade, while climate-driven permafrost thaw, shrubification, and fire are accelerating across much larger areas. Loss Rate

Primary Threats

Climate Change Infrastructure Mining Pollution Human Disturbance Resource Depletion Hunting Human-Wildlife Conflict Invasive Species Disease Natural System Modification

Protection Efforts

  • Expansion and improved management of Arctic protected areas and ecological networks (national parks, reserves, wilderness areas).
  • Indigenous-led stewardship, co-management of wildlife (e.g., caribou/reindeer), and protection of subsistence resources.
  • Stronger environmental review and mitigation for linear infrastructure (routing, seasonal restrictions, roadless policies, spill prevention).
  • Protected-area connectivity planning to maintain migration routes and climate refugia.
  • Arctic pollution controls (spill response capacity, restrictions on certain contaminants) and monitoring of long-range pollutants.
  • Climate mitigation policies (global emissions reductions) and adaptation planning for permafrost, wildfire, and coastal erosion impacts.
Fun Facts

Did You Know?

"Treeless" doesn't just mean "too cold": trees struggle largely because permafrost blocks deep roots and creates waterlogged, low-oxygen soils in summer, while fierce winds and abrasion add stress.

A desert that can feel soggy: despite low precipitation, tundra often has marshy ground in summer because frozen subsoil prevents drainage and meltwater can't soak in deeply.

Snow can be a blanket, not just a hazard: a thick snowpack insulates the ground, helping some plants and small animals survive by keeping temperatures under snow far warmer than the air above.

Tiny plants can be powerhouses: mosses and lichens can photosynthesize at very low temperatures and low light, letting them dominate where taller plants can't compete.

Summer can be a feeding frenzy: explosive insect blooms (especially mosquitoes and midges) can happen because shallow water and long daylight speed up short life cycles.

Wildlife "changes outfits": many tundra animals (e.g., Arctic fox, ptarmigan) switch to white winter camouflage and back to darker summer colors-seasonal fashion for survival.

Permafrost carbon scale: the carbon stored in permafrost is on the order of roughly double the carbon currently in Earth's atmosphere-like a gigantic savings account that can "leak" if thawed.

A short growing season: many tundra plants have only ~6-10 weeks to grow, flower, and set seed-more like a sprint than a marathon compared with temperate ecosystems.

Root depth vs. a dinner plate: in many tundra areas, the "active layer" that thaws each summer can be shallow enough that most roots stay close to the surface, forcing plants to spread wide rather than dig deep.

Landscape as a patchwork quilt: tundra often alternates between dry hummocks, wet hollows, and shallow ponds over just a few steps, because freeze-thaw processes sort soils into repeating microhabitats.

Migration superhighway: huge numbers of birds breed on tundra during the brief summer, then disperse across continents-turning a seemingly empty landscape into a seasonal international hub.

Earth's biggest tundra: the Arctic tundra forms the planet's largest tundra region, ringing the Arctic Ocean across North America, Greenland, Scandinavia, and Siberia.

One of the planet's largest long-term carbon vaults: permafrost (a defining tundra feature) locks away roughly ~1,500 billion metric tons of organic carbon-more than is currently in the atmosphere.

Some of the oldest "individuals" can be tundra plants: many dwarf shrubs and sedges grow clonally (one genetic individual spreads), allowing single clones to persist for centuries to millennia in harsh conditions.

The "fastest-warming" biome neighborhood: the Arctic has warmed several times faster than the global average in recent decades (Arctic amplification), making tundra landscapes among the most rapidly changing on Earth.

One of the most extreme seasonal light regimes: tundra near the poles experiences some of the longest continuous daylight (midnight sun) and darkness (polar night) on land.

Tundra Animals

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