The tundra is one of the least species-rich biomes on the planet, with far fewer plants, animals, and fish than forests, grasslands, or wetlands at lower latitudes. Short growing seasons, extreme cold, and permafrost create conditions that most organisms simply cannot tolerate. Yet the tundra’s ecological story is not just about what is missing. The biodiversity it does support is tightly wired into food webs with little backup, harbors a surprisingly rich microbial world belowground, and is changing faster than almost any other biome as the climate warms.
How Plant Diversity Stacks Up
The tundra’s plant communities are sparse by almost any measure. Across the circumpolar Arctic, you find grasses, sedges, dwarf shrubs, mosses, and lichens, but the total count of vascular plant species is a fraction of what temperate or tropical ecosystems support. A typical square meter of tropical rainforest floor can host dozens of plant species; a similar patch of tundra might hold fewer than ten. The flora is dominated by low-growing, slow-reproducing species adapted to frozen soils and a growing season that can last as little as six to ten weeks.
Within the tundra, though, diversity varies in interesting ways depending on what kind of plant you look at. Vascular plants and lichens tend to reach their highest richness in moderately low-productivity areas, while mosses and their relatives peak in the least productive habitats.
1Ecography. Productivity–diversity patterns in arctic tundra vegetationThat pattern flips the familiar logic of “more resources, more species.” In the tundra, the spots with the most plant growth tend to be dominated by a few aggressive species, usually graminoids or shrubs, which crowd out competitors. The more marginal patches, where no single growth form can dominate, end up supporting a wider variety of lichens and bryophytes.
Dispersal ability also shapes which groups are most diverse and where. Lichens, which spread easily through airborne fragments, show relatively even species composition across vast distances. Vascular seed plants, which disperse less readily, show sharper differences in species makeup from place to place across the Eurasian Arctic.
2Global Ecology and Biogeography. Dispersal ability links to cross‐scale species diversity patterns across the Eurasian Arctic tundraIn practical terms, that means a lichen community in Svalbard can look a lot like one in Siberia, while the flowering plants in those two places may barely overlap.
Animal Life on the Tundra
Tundra fauna is limited but not negligible. The circumpolar Arctic supports roughly 88 species and 228 subspecies or distinct flyway populations of terrestrial birds, including shorebirds, waterfowl, raptors, and passerines.
3PubMed Central. Status and trends of tundra birds across the circumpolar ArcticThat sounds like a reasonable number until you compare it to temperate forests or tropical regions where a single national park might harbor hundreds of bird species. Still, Arctic-breeding birds punch above their weight ecologically. Many are long-distance migrants whose populations connect the tundra to wetlands and coastlines on every continent.
Shorebird richness is not spread evenly across the Arctic. Two broad regions stand out: a species-rich zone centered on Beringia, the region around the Bering Strait where Alaska and Siberia nearly touch, and a species-poor zone centered on the Atlantic Arctic. The difference traces to productivity, the length of the snow-free season, how many migratory flyways converge on an area, and how much tundra habitat existed during the last ice age.
4Journal of Biogeography. Patterns and determinants of shorebird species richness in the circumpolar ArcticBeringia largely escaped glaciation during the Pleistocene, giving species more time to accumulate and diversify there.
Among mammals, the cast is small: caribou, muskoxen, Arctic foxes, wolves, polar bears along coastlines, and several species of lemmings and voles. Invertebrate diversity is harder to pin down because it has been less thoroughly studied, though anyone who has spent a summer in the Arctic can attest to the overwhelming abundance of mosquitoes, blackflies, and botflies. These biting insects are an extreme and characteristic presence, even if the number of species involved is relatively low.
5PubMed Central. Biting insects in a rapidly changing ArcticFreshwater Fish Tell a Stark Story
If you want a clear illustration of how harsh the tundra is for biodiversity, look at freshwater fish. In the high Arctic, above roughly 71°N, the entire freshwater fish community collapses to a single species: Arctic charr. Overall, gamma diversity (the total number of species across a region) drops dramatically in the high Arctic compared to lower-latitude zones. Below 71°N, individual lakes and rivers can still host a reasonable number of fish species, and the overall species pool is richer, but composition changes sharply from one region to the next.
6Freshwater Biology. Circumpolar patterns of Arctic freshwater fish biodiversity: A baseline for monitoringThe high Arctic’s fish poverty reflects not only present-day cold but also glacial history. Many freshwater systems were scoured by ice sheets and have had only a few thousand years to be recolonized.
Why Simple Food Webs Matter More Than They Seem
One of the tundra’s defining ecological features is that its food webs are short and relatively uncomplicated. There are fewer species at every level, from primary producers up through herbivores to predators. That simplicity might suggest the system is uninteresting, but it actually makes the tundra unusually sensitive. With fewer species filling each role, the loss or decline of any single one ripples outward more powerfully than it would in a richer ecosystem.
Lemmings illustrate this perfectly. These small rodents are a key component of tundra food webs, and shifts in their population dynamics can affect the entire ecosystem.
7PubMed Central. Documenting lemming population change in the Arctic: Can we detect trends?When lemming numbers crash, Arctic fox, snowy owl, and skua populations suffer, and those predators shift to alternative prey like shorebird eggs, sending secondary effects cascading through bird communities. When lemmings boom, their intense grazing reshapes the vegetation. Predation pressure on lemmings varies with prey density and may contribute to the dramatic population cycles the species is famous for.
8PubMed. Disentangling trophic relationships in a High Arctic tundra ecosystem through food web modelingThe tundra’s broad range of plant growth forms, from mosses and lichens to graminoids and dwarf shrubs, combined with low functional redundancy, means that when the dominant plant type in an area shifts, a complex series of biological cascades follows. The effects are not limited to plants. Changes in vegetation alter soil temperature, moisture, nutrient cycling, and habitat for invertebrates and nesting birds.
9Global Change Biology. Ecosystem feedbacks and cascade processes: understanding their role in the responses of Arctic and alpine ecosystems to environmental changeIn a tropical forest, if one tree species declines, dozens of functional equivalents can fill the gap. In the tundra, there may be no backup.
The Microbial World Beneath the Surface
The tundra looks barren aboveground, but belowground is a different story. Permafrost soils harbor a microbial community that is both diverse and highly variable from site to site. Across Arctic permafrost, bacteria from the Proteobacteria and Actinobacteria groups dominate, averaging about 41% and 20% of the total community respectively. Other abundant groups, including Firmicutes, Bacteroidetes, and Chloroflexi, show substantial variation in their distribution across sites.
10PubMed Central. Permafrost microbial communities and functional genes are structured by latitudinal and soil geochemical gradientsThis microbial diversity matters far beyond taxonomy. These communities drive nutrient cycling, decompose organic matter, and play a central role in the tundra’s massive carbon stores. Tundra ecosystems hold large stocks of soil organic matter, likely because cold temperatures slow microbial decomposition more than they slow the accumulation of organic material from plant productivity and microbial remains.
11Soil Biology and Biochemistry. Plant-microbial linkages underpin carbon sequestration in contrasting mountain tundra vegetation typesThe size, structure, and physiology of the soil microbial community are strongly linked to aboveground plant community characteristics, making plant diversity a practical surrogate for assessing the tundra’s carbon storage potential.
So when people ask whether the tundra has high biodiversity, the honest answer depends partly on where you look. On the surface, no. Underfoot, the picture is considerably richer and more complicated.
Polyploidy and Hidden Genetic Complexity
Standard species counts may actually underestimate the tundra’s biological complexity. The Arctic is one of Earth’s most polyploid-rich areas, meaning many of its plant species carry extra sets of chromosomes. The frequency and level of polyploidy increase strongly as you move northward within the Arctic.
12Oxford Academic. Polyploidy in arctic plantsPolyploidy is not just a chromosomal curiosity. Plants with extra chromosome sets often have broader ecological tolerances, greater cold hardiness, and the ability to reproduce without pollinators through self-fertilization or asexual seed production. For tundra plants, these are critical survival traits. Polyploidy can also blur species boundaries. What looks like a single species based on outward appearance might encompass multiple genetically distinct lineages that arose through separate whole-genome duplication events. This cryptic diversity means the tundra’s genetic richness is higher than its species list suggests, and it has practical implications for conservation: protecting one population of a “species” may not conserve all of its genetic diversity.
How Climate Change Is Reshaping Tundra Biodiversity
The Arctic is warming two to four times faster than the global average, and the effects on tundra biodiversity are already visible. One of the most documented changes is shrubification: woody shrubs are expanding into areas previously dominated by grasses, mosses, and lichens. Model predictions suggest that as woody plants expand, species richness will decrease, species turnover will accelerate, and local extinction risk for the plants currently growing there will increase.
13Environmental Research Letters. Arctic shrubification mediates the impacts of warming climate on changes to tundra vegetationObservational data backs this up: shrub expansion, particularly of taller erect shrubs, has been associated with greater species losses and decreasing species richness in Arctic plant communities.
14PubMed Central. Plant diversity dynamics over space and time in a warming ArcticAlongside shrubification, a parallel process called borealization is underway. Species from the boreal forest, the biome just south of the tundra, are moving northward and upward into tundra territory.
15Environmental Research Letters. Borealization of tundra ecosystems with climate and land-use changeA synthesis of data from 32 study areas and over 1,100 plots resurveyed between 1981 and 2023 confirmed that boreal and boreal-tundra species are colonizing tundra and increasing in abundance.
16Ecology Letters. Borealisation of Plant Communities in the Arctic Is Driven by Boreal-Tundra SpeciesThis creates a paradox. Total species counts at a given tundra site may temporarily rise as newcomers arrive from the south. But the species being gained are widespread boreal generalists, while the species being lost are cold-adapted tundra specialists that exist nowhere else. The net effect is a homogenization of the Arctic flora, not a genuine enrichment. For cold-adapted animals, the picture is similar: modeling predicts that tundra-specialist mammals will see their ranges contract into a few discrete refugial areas as habitat shrinks, even as boreal species expand northward.
17Ecosphere. Arctic biodiversity: increasing richness accompanies shrinking refugia for a cold‐associated tundra faunaPermafrost Thaw and Shifting Habitats
Climate change is not only moving species around; it is physically remaking the tundra landscape. As permafrost thaws, the ground surface subsides unevenly, creating a patchwork of wet depressions and drier mounds known as thermokarst terrain. In older, more heavily subsided areas, the variability in soil moisture increases: some microsites become waterlogged while others dry out.
18Ecosystems. Plant Species Composition and Productivity following Permafrost Thaw and Thermokarst in Alaskan TundraGraminoids tend to colonize the cold, dry patches, while mosses and shrubs favor the warm, moist ones. In one sense, thermokarst can increase habitat heterogeneity and potentially support more species across a landscape. But it also disrupts existing plant communities, accelerates decomposition of ancient soil carbon, and can drown or strand species that depended on the old surface conditions.
For the tundra’s carbon stores, these changes are consequential. Permafrost soils contain roughly twice as much carbon as the entire atmosphere. When permafrost thaws, microbial communities that have been essentially dormant for thousands of years begin decomposing that stored organic matter, releasing carbon dioxide and methane. The speed and magnitude of this release depend partly on which plant and microbial communities take hold on the newly thawed ground, linking biodiversity directly to a global climate feedback.
Parasites and Overlooked Ecological Roles
When tallying tundra biodiversity, parasites rarely make the brochure, but they are ecologically significant. Host-parasite interactions in the Arctic occur in an environment of extremes: highly seasonal, frigid, and supporting low host species abundance and diversity.
19PubMed Central. A walk on the tundra: Host-parasite interactions in an extreme environmentArctic caribou and muskoxen carry gut nematodes, lungworms, and protozoans. Warble flies and botflies parasitize caribou herds so heavily that the animals alter their migration routes to avoid peak fly activity. In lemmings, parasites may influence population cycling by weakening individuals during certain phases of the boom-bust cycle.
Warming is already changing the parasite picture. Higher temperatures can shorten parasite development times, expand the active season for insect vectors, and allow parasites from lower latitudes to colonize new Arctic hosts. For wildlife managers and Indigenous communities that depend on caribou and other subsistence species, these shifts are more than academic. A parasite fauna that was once kept in check by cold is becoming more diverse and more virulent, adding yet another stressor to tundra animal populations that are simultaneously losing habitat to shrub encroachment and borealization.
Why the Tundra’s Low Biodiversity Still Demands Attention
Shifts in the distribution and composition of Arctic plants are expected to increase with continued global warming, with knock-on effects for the carbon cycle that extend well beyond the Arctic itself.
20PubMed. The changing biodiversity of the Arctic flora in the AnthropoceneThe tundra’s low species richness is precisely what makes each remaining species so important. In species-poor systems, every organism fills a larger share of the ecosystem’s functional roles. Lose a single keystone herbivore or a dominant moss species, and the consequences cascade further than they would in a system with dozens of functional substitutes.
That framing resets how we should think about tundra biodiversity. The question is not just whether the number is high or low but whether the biodiversity present is adequate to keep the ecosystem functioning. The evidence increasingly suggests the answer is: barely, and the margin is shrinking. Tundra specialists are being replaced by boreal generalists, shrub expansion is flattening plant communities, permafrost thaw is reshuffling microbial and plant assemblages, and parasites are diversifying in ways that add stress to already constrained animal populations. Each of these trends, individually manageable, compounds the others in a system with almost no ecological slack.