What’s Earth’s Dominant Species By Mass?

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A September 2026 report compares species by total biomass and finds cattle are the heaviest animal species by its estimates. Among plants, black spruce and Dahurian larch are leading candidates, but the available inventory data do not establish a definitive global winner. The result depends on how biomass is measured and how completely species are counted.

A report published September 27, 2026, estimates that no animal species comes close to the biomass of some boreal trees: black spruce in Canada accounts for more than 11 billion tonnes of growing wood, while Dahurian larch in Russia may account for at least 8.4 billion tonnes. The figures suggest that trees could be Earth’s dominant species by mass, but the report does not establish a definitive global winner because the estimates use different sources and methods.

The comparison depends on what counts as mass. The report gives approximate total masses for individual animal species, then uses a major 2018 study that measures the mass of life by its carbon content to compare biological kingdoms. In the animal category, it estimates cattle at about 650 million metric tons of total mass, humans at about 350 million and wild Antarctic krill at about 379 million. Those estimates come from different cited sources and should be read as approximate, not as a single synchronized census.

For plants grown by people, the report points to harvest data rather than a direct count of all living plants. Global sugar-cane production exceeded 2 billion metric tons in 2023, according to the figures it cites; maize production was about 1.1 billion tonnes. Harvest volume is not the same as the standing biomass of a species, but sugar cane’s perennial roots persist between harvests, making its living mass a relevant part of the comparison.

The leading wild-tree candidates are black spruce and Dahurian larch, both associated with boreal forests. The report cites Canada’s National Forest Inventory for its estimate of more than 11 billion tonnes of black spruce in Canada, with some also growing in the United States. For Russia, it calculates at least 8.4 billion tonnes of Dahurian larch from broader forest figures and assumptions about the share of larch species. That is an estimate, not a species-level total reported directly by Russia’s forest inventory.

Why Tree Biomass Changes the Comparison

The estimates challenge the familiar focus on people and livestock when comparing the mass of species. Cattle lead among animals in the report’s figures, but animal biomass is only a small part of the total mass of life. The 2018 study by Bar-On and colleagues estimates about 450 billion tonnes of carbon in plants, compared with roughly 2 billion tonnes in animals. Those are kingdom-wide carbon estimates, not a direct ranking of every species, but they show why the likely candidates for the overall lead are plants rather than animals.

That distinction matters for understanding the biosphere and human influence on it. Cattle, crops and forests are not interchangeable measures: livestock totals describe living animals, crop harvests record material collected over a year, and forest inventories estimate standing stocks. A large harvest does not by itself prove a crop species has the greatest living mass. The report’s tree estimates likewise show the possible scale of individual forest species while leaving room for uncertainty about their global totals.

How the Biomass Estimates Compare

The report starts by correcting a common comparison: ants are not as heavy as humans collectively in the cited estimates. But comparing all ants with people also groups many ant species against one human species. Its central question is narrower: which single species has the greatest total mass across its members?

For animals, the report puts cattle ahead of humans, krill and pigs. Its broader biological comparison relies on the 2018 paper by Bar-On et al., which measures biomass in carbon rather than total wet mass. Carbon is only part of an organism’s mass, but the measure helps compare how much biological material is present across kingdoms. Under that study’s estimates, plants outweigh fungi, bacteria, archaea, protists, animals and viruses by carbon mass.

The report then turns to boreal forests, where a few tree species can account for a large share of forest mass. It cites research describing this concentration and uses national forest data to assess black spruce and larch. The figures cover different geographic areas, years and levels of detail. They identify plausible contenders, but they are not a standardized global inventory of every species.

““Humans are pretty close to the top for a single species.””

— Signore Galilei report, September 27, 2026

Why No Species Is Confirmed as Winner

The report does not establish a definitive winner across all species. Its black-spruce figure is a Canadian estimate, with additional trees in the United States not quantified in the same total. The Dahurian-larch figure is derived from Russian forest area, the estimated share of larch and an assumption about how that share divides between two species. The report notes that Russia’s inventory does not provide the same level of species-specific detail.

There is also a measurement gap between total organism mass, carbon mass, annual crop harvest and standing forest stock. These quantities answer related but different questions. Some bacteria live deep underground in aquifers and seafloor sediments, environments that are difficult to study; the report says one dominant bacterial species could potentially be a contender. The available figures do not resolve that possibility or provide a uniform, current global census across all species.

Better Inventories Could Refine the Ranking

The ranking could change as forest inventories publish more species-level data and researchers improve estimates for hard-to-sample ecosystems, especially deep subsurface habitats. A stronger comparison would need consistent definitions of biomass, comparable time periods and global coverage for the candidate species. Until then, the report supports a cautious conclusion: cattle lead among animals, while boreal trees are plausible leaders among species overall, rather than a confirmed universal champion.

Key Questions

What species does the report identify as the heaviest?

It identifies black spruce and Dahurian larch as leading candidates, but does not confirm one overall winner. Its estimates cover different regions and rely on different methods.

Which animal species has the greatest biomass in the report?

Cattle, estimated at about 650 million metric tons of total mass. The report compares that with about 350 million tonnes for humans and 379 million tonnes for Antarctic krill.

Does the report say humans outweigh ants?

Yes. It says the idea that all ants weigh as much as all humans is not supported by the cited estimates, which put humans at roughly five times the mass of ants.

Why does the report use carbon mass?

The cited 2018 study uses carbon to compare biomass across kingdoms of life. Carbon is only part of an organism’s total mass, so carbon figures should not be confused with wet or total mass estimates.

Could a bacterium still be the largest species by mass?

The report says that possibility cannot be ruled out because many bacteria live in difficult-to-study aquifers and seafloor sediments. It considers a plant more likely to lead, but the evidence cited does not settle the question.

Source: hn