Does Antarctica Have Trees? A Look at Its Past and Present

Antarctica today is treeless, and has been for millions of years. The continent’s only native vascular plants are two small, ground-hugging species: a grass and a cushion-forming herb. But this barren landscape is a relatively recent development in geological terms. For most of the past 300 million years, Antarctica supported forests that ranged from sprawling seed-fern woodlands to lush conifer rainforests that would have looked at home in modern New Zealand. The story of how a continent went from forested to frozen involves shifting tectonic plates, plummeting carbon dioxide levels, and one of the most dramatic ecological collapses in Earth’s history.

What Grows on Antarctica Now

The Antarctic continent’s living vegetation is overwhelmingly non-vascular. Lichens, mosses, liverworts, and algae dominate, clinging to exposed rock and coastal fringes where conditions are just barely tolerable. Only two native species of flowering plants exist on the entire continent: Antarctic hair grass (Deschampsia antarctica) and Antarctic pearlwort (Colobanthus quitensis). Both are small, low-growing plants found mostly on the Antarctic Peninsula and nearby islands, and both likely arrived on a relatively recent geological timescale, during the late Pleistocene.¹

These two species have been expanding in recent decades. Monitoring over a 27-year period found significant increases in both the number of individuals and the number of populations at widely separated sites in the maritime Antarctic, strongly linked to a warming trend in summer air temperatures that has been evident since the late 1940s.² But even with this expansion, neither species grows more than a few centimeters tall. They are about as far from a tree as a vascular plant can get.

On the sub-Antarctic islands just north of the continent, the plant life is richer but still lacks anything resembling a forest canopy. Native and alien plant communities there are dominated by herbs and grasses, with woody species largely absent from the colder islands.³ You would need to travel considerably farther north, to places like southern Chile or New Zealand’s subantarctic islands, before encountering anything that could be called a tree.

The Permian Seed-Fern Forests

Rewind roughly 260 million years and the picture is unrecognizable. During the Permian period, Antarctica sat at high southern latitudes as part of the supercontinent Gondwana, yet it was covered in forests dominated by Glossopteris, a group of seed ferns with broad, tongue-shaped leaves. These were not scraggly survivors clinging to the edge of habitability. Fossil sites in the Transantarctic Mountains reveal well-developed forests with dozens of in-place tree stumps. At Lamping Peak in the upper Buckley Formation near the Beardmore Glacier area, two closely spaced bedding planes contain 53 and 21 in-place stumps respectively, along with abundant plant fossils that allow researchers to reconstruct the structure and biomass of these forests, which grew at roughly 75° south paleolatitude.⁴

The shales in which these stumps are rooted contain numerous Glossopteris leaves, painting a picture of a forest floor carpeted in shed foliage.⁵ These forests were clearly productive ecosystems, not marginal ones. The title of that 1992 paper sums up the central lesson neatly: “the present is not the key to the past.” What works as an explanation for modern polar ecosystems completely breaks down when you try to apply it to the deep past.

Silicified peat from other Permian sites in the Transantarctic Mountains tells the same story. Collections from Collinson Ridge show a low-diversity flora overwhelmingly dominated by Glossopteris, preserved in such detail that individual leaf anatomy can be studied.⁶ One reason for Glossopteris‘s dominance may be its underground partnerships. Fossil roots show fungal associations that likely helped these seed ferns thrive in soils that might otherwise have been nutrient-poor, a relationship that may partly explain why Glossopteris-type plants dominated across the entirety of southern Gondwana during this era.⁷

Triassic Conifers and the Challenge of Polar Light

After the end-Permian mass extinction wiped out Glossopteris and much of the planet’s flora, Antarctica’s forests did not disappear. They were replaced. By the Middle Triassic, roughly 240 million years ago, conifers and other gymnosperms had colonized the continent. Fossil forests from this period show something that earlier climate models said should have been impossible: thriving tree communities at latitudes where temperature extremes were thought to prevent growth entirely. Tree ring analysis from these Triassic fossils tells a different story, indicating growing seasons that were very favorable for plant life.⁸

That said, growing at polar latitudes came with a unique challenge: months of total darkness in winter, followed by months of continuous light in summer. Tree rings from both Permian and Triassic woods show a distinctive structure. They consist almost entirely of earlywood, with only a tiny percentage classified as latewood, typically amounting to just a few cells wide. This pattern indicates that trees transitioned very rapidly into seasonal dormancy, probably in direct response to declining light levels rather than temperature.⁹ The growing season was intense but compressed: trees would pour energy into growth during the months of continuous sunlight, then shut down as the sun sank below the horizon.

Not all trees coped equally well. A recently described dwarf conifer from the Triassic of Antarctica had one of the slowest growth rates in the entire fossil record, averaging just 0.2 millimeters per season. The surrounding geological evidence and ring data from other trees at the same locality show that conditions were not unusually harsh, so this particular tree may represent early evidence of suppressed growth from some other cause, perhaps genetic, perhaps related to competitive shading.¹⁰ Fossil wood from other Triassic sites in East Antarctica, including specimens collected during the first Korea Antarctic Geological Expedition, confirm that conifer forests were widespread across the continent during this period.¹¹

These ancient trees also maintained sophisticated underground symbioses. Fossilized root nodules from a Middle Triassic conifer called Notophytum, preserved in Antarctic peat, contain fungal structures identical in function to the mycorrhizal partnerships that help modern trees absorb nutrients. This discovery pushed the known origin of the conifer-mycorrhizal relationship back to at least the early Mesozoic.¹²

Cretaceous Rainforests at the Bottom of the World

Antarctica’s forests arguably reached their peak complexity during the Cretaceous period, roughly 100 million years ago, when the planet was in the grip of a greenhouse climate far warmer than today’s. On Alexander Island, off the Antarctic Peninsula, well-preserved fossil plant communities show something remarkable: spatially complex forests comparable in structure and composition to the temperate rainforests of present-day New Zealand. These were not uniform woodland but varied by terrain. Coastal meander belts supported medium-density forests of podocarp and araucarian conifers, about 568 trees per hectare on mature floodplain soils. Floodplain braided rivers supported patchier, lower-density stands of about 91 trees per hectare, interspersed with thickets of ferns, cycads, and early flowering plants.¹³

The range of disturbances these forests experienced also sounds familiar: flooding, frost damage, insect and fungal attack, and wildfire all left traces in the fossil record. These were not alien ecosystems from some unrecognizable world. If you could travel back in time and walk through them, the experience would feel broadly similar to a walk through a wet, cool forest in the southern hemisphere today, though with very different light conditions and unfamiliar species overhead.

The Eocene Peak and the Forests’ Long Decline

As the Cretaceous gave way to the Paleocene and then the Eocene, Antarctica’s forests persisted and even remained diverse. Fossil wood from the lower Paleocene Sobral Formation on the Antarctic Peninsula includes seven different conifer wood types, with araucarian woods being the most common, followed closely by podocarps.¹⁴ By the early Eocene, about 50 million years ago, podocarps had taken the lead. A study of 120 fossil wood samples from the La Meseta Formation found that conifers made up about 68% of all wood samples, with podocarp species being the most common, followed by what are likely cupressaceous and araucarian conifers.¹⁵

Alongside these conifers, southern beech trees of the genus Nothofagus became a major component of Antarctic forests. Molecular clock analyses suggest southern beeches were likely present in Antarctica as recently as 25 million years ago, and the continent served as a bridge for the dispersal of Nothofagus lineages between South America and Australasia.¹⁶ If you visit a Nothofagus forest in Patagonia or Tasmania today, you are looking at the distant relatives of trees that once flourished on Antarctic soil.

The decline began in the late Eocene. Mountain glaciation appeared on the Antarctic Peninsula around 37 to 34 million years ago, accompanied by a drop in atmospheric CO₂ concentrations and a decrease in the diversity of the angiosperm-dominated vegetation that had covered the northern peninsula.¹⁷ A key tectonic trigger was the opening of the Drake Passage between South America and Antarctica, which allowed the Antarctic Circumpolar Current to form. This current thermally isolated the continent from warmer ocean water, accelerating the cooling.¹⁸

The forests did not vanish overnight. Despite cooling and growing ice sheets, Nothofagus-dominated forests held on without dramatic changes in composition until the early Oligocene, roughly 33.5 to 32 million years ago. Then came a rapid shift: gymnosperms and cryptogams expanded markedly, replacing the broadleaf-dominated communities. Glacial-related environmental disturbance, including ice erosion and transport, appears to have broken Nothofagus‘s dominance and allowed other vegetation types to expand into newly disturbed ground.¹⁹

The Last Trees on the Continent

The most startling chapter in Antarctica’s botanical history may be the end of it. Fossil leaves from the Pliocene Sirius Group at Oliver Bluffs in the Transantarctic Mountains, deposited roughly 3 to 5 million years ago, belong to a newly described species of southern beech, Nothofagus beardmorensis. This species was winter deciduous, shedding its leaves annually. The presence of leaves, wood, and pollen together in the same sediments suggests they all came from the same species, growing in place.²⁰

The implications are striking. No living Nothofagus species can survive winter temperatures below about −22°C, and the trees need temperatures well above freezing for a substantial growing season to support the level of growth and reproduction observed in the fossils. If these dates are correct, as recently as the Pliocene, parts of Antarctica’s interior experienced conditions dramatically warmer than today. This would have been a low, scrubby woodland rather than a tall forest, but it was unmistakably a community of trees growing on what is now one of the coldest places on Earth.

The Sirius Group deposits remain somewhat controversial. Some researchers have questioned whether the fossils could have been reworked from older sediments rather than growing in place during the Pliocene. New techniques for identifying reworked versus contemporaneous pollen in Antarctic marine sediment cores are helping to resolve these kinds of questions. By using fluorescence characteristics and digital imaging, researchers can now better distinguish fossil pollen that is the same age as its host sediment from grains that have been eroded out of much older rock and redeposited.²¹

Why Deciduous, Not Evergreen

A long-running debate in paleobotany concerns why many of Antarctica’s ancient trees were deciduous rather than evergreen. The intuitive argument, advanced for about 50 years, was that deciduous trees saved carbon by avoiding the respiratory cost of maintaining leaves through the months of continuous polar darkness during winter. It sounds sensible: if your leaves cannot photosynthesize in total darkness, why keep them?

But experiments designed to test this idea by measuring the actual winter carbon balance of “living fossil” tree species in simulated warm polar climates found the opposite. The carbon cost of dropping all your leaves every autumn and regrowing them in spring far exceeds the respiratory cost of simply maintaining an evergreen canopy through winter darkness. Mathematical modeling supports this finding across a wide range of latitudes.²² The real adaptive advantage of deciduousness in these polar forests may have had more to do with frost protection or other environmental stresses than with carbon budgets during the dark season. This is one of those cases where a seemingly obvious explanation turned out to be wrong when someone finally ran the experiment.

Could Warming Bring Trees Back

With Antarctica’s climate warming, especially along the Peninsula, it is natural to wonder whether trees could eventually recolonize the continent. The short answer is that we are nowhere close. Current warming is producing measurable changes in the two existing vascular plant species, but the conditions that supported Antarctic forests, mean annual temperatures above freezing, deep unfrozen soils, and atmospheric CO₂ levels far higher than today’s, are not on any near-term trajectory to return. In maritime Antarctica, where warming has been most pronounced, vegetation is expected to increase in productivity and cover, but the species involved are mosses, lichens, and the existing hair grass and pearlwort, not trees.²³

Ironically, the bigger concern is not whether trees will return naturally but whether human activity might introduce non-native plants before the ecosystems are ready. Research on potential plant invasions suggests that warming enhances priority effects in plant community assembly, meaning the order in which new species arrive and how quickly they germinate could shape the future of Antarctic plant communities in unpredictable ways.²⁴ Seeds hitchhiking on visitors’ boots and clothing are a more realistic near-term threat than climate-driven reforestation.

Meanwhile, the existing native species face their own uncertainties under warming. Field experiments using passive warming chambers on the Antarctic Peninsula found that while warmer conditions early in the growing season were beneficial, the chambers ultimately intensified drought stress and extreme heat events. Antarctic hair grass suffered reduced photosynthesis and a notable decrease in a key stress-tolerance trait, while the pearlwort remained relatively unaffected.²⁵ Continental Antarctica, deeper inland, appears to be heading toward even drier and harsher conditions despite global warming trends. The relationship between warming and plant success on the continent is far from straightforward, and the idea that a warmer Antarctica simply means a greener one oversimplifies what is actually happening on the ground.