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A report published Sept. 27 estimates that black spruce and Dahurian larch each outweigh any animal species by a wide margin, though the tree rankings rely on incomplete, indirect calculations. The answer depends on what “mass” means: estimates of whole-organism weight differ from comparisons based on carbon biomass, and no definitive global species ranking is established.
A report published Sept. 27 identifies black spruce and Dahurian larch as leading candidates for the most massive species on Earth, with estimated totals of more than 11 billion tonnes and at least 8.4 billion tonnes, respectively. The figures suggest individual tree species may outweigh animals by a wide margin, but they are estimates assembled from national forest data, and the report does not establish a definitive global winner.
The comparison begins with animals, where cattle are estimated at about 650 million metric tonnes of total body mass. Humans are estimated at roughly 350 million tonnes, close to Antarctic krill, for which a 2009 estimate put biomass at 379 million tonnes. The report says pigs weigh about 140 million tonnes in total. These figures refer to whole-organism mass, not carbon alone.
For plants, the report distinguishes harvested crops from standing wild vegetation. Sugar cane had a 2023 harvest exceeding 2 billion metric tonnes, according to the figures cited, but that is annual production rather than a direct count of all living sugar cane at one time. Because sugar cane is perennial, its living mass may exceed that of an annual crop such as maize, the report says, without giving a full global standing-biomass estimate.
The wild-tree estimates are larger but less direct. The report cites Canadian inventory data showing more than 11 billion tonnes of black spruce in Canada, with some trees also growing in the United States. For Dahurian larch, it estimates at least 8.4 billion tonnes in Russia by allocating part of the country’s reported larch forests to that species. The author says the estimate could be higher, but it depends on assumptions about the share of Russian larch represented by Dahurian larch.
Why Tree Biomass Changes the Ranking
The comparison challenges the intuition that the largest species by mass must be a large animal or a familiar food crop. Individual wild tree species may represent billions of tonnes of living material, far exceeding the estimated mass of cattle, humans or krill. That matters because biomass is one way researchers describe how living material is distributed across the biosphere.
But a ranking by total weight is not the same as a measure of ecological influence or abundance per area. Nor does it show that people have little effect: the report notes that humans raise enormous numbers of livestock and cultivate crops at scale. The useful takeaway is narrower: depending on the measurement and species boundaries, boreal trees are candidates for the highest species-level biomass, while exact comparisons remain difficult.
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Two Measures, Different Comparisons
The report uses “biomass” in two related ways. Animal and crop examples are often given as total wet or whole-organism mass, while a widely cited 2018 study by Bar-On and colleagues compared broad groups of life by carbon mass. Carbon is only one component of an organism, so these totals are smaller and are not directly interchangeable with whole-body weights.
In the 2018 study’s estimates, plants contained about 450 billion tonnes of carbon, compared with 70 billion for bacteria, 12 billion for fungi, 7 billion for archaea, 4 billion for protists and 2 billion for animals. The report says cattle’s estimated 650 million tonnes of total mass correspond to about 61 million tonnes of carbon. The kingdom-wide figures show plants dominate carbon biomass overall, but they do not identify a single top species.
Species-level estimates face further challenges. Some organisms are difficult to sample, and forests contain many species whose abundance varies by region. The article points to the boreal forest belt, where a few tree species can account for a large share of forest mass, as a setting in which one species could plausibly accumulate unusually high biomass.
“Humans are pretty close to the top for a single species, weighing in at about 350 million metric tons.”
— Signore Galilei report
Why the Species Winner Is Unsettled
The report presents candidates, not a settled scientific ranking. The black spruce estimate cited covers Canada, while the Dahurian larch calculation uses Russia’s forest area and an assumed split between larch species. The report says Russia’s inventory does not provide species-level figures detailed enough to directly confirm the Dahurian larch total. The two estimates also rely on different data and methods, limiting a like-for-like comparison.
There is additional uncertainty for organisms that are hard to measure. The article notes that much bacterial biomass is found in aquifers and seafloor sediments, where sampling is difficult, and raises the possibility that a single bacterial species could have very high biomass. It does not provide a species-level global estimate that resolves that possibility. The precise answer also depends on whether “mass” means wet weight, dry weight or carbon mass, and on how a species’ geographic range and living material are counted.
Better Inventories Could Refine the Ranking
The estimates could change as forest inventories add more species-level measurements and researchers improve biomass estimates for hard-to-sample environments. A direct global comparison would need consistent methods across species, regions and types of organism, including a clear choice between whole-organism mass and carbon content.
For now, the report’s strongest conclusion is that black spruce and Dahurian larch are plausible leaders under the estimates it assembles, not that either has been proven to be Earth’s most massive species. No new measurement or ranking is announced in the source; the next step is improved data that can test the tree estimates against one another and against less-studied organisms.
Key Questions
What species does the report identify as the leading candidates?
It names black spruce, estimated at more than 11 billion tonnes in Canada, and Dahurian larch, estimated at at least 8.4 billion tonnes in Russia. The figures are not a definitive global ranking.
Are cattle the heaviest species by total animal mass?
The report estimates cattle at about 650 million metric tonnes, more than its estimates for humans, Antarctic krill or pigs. Those are whole-organism mass estimates, not carbon biomass.
Why is sugar cane included in the comparison?
Sugar cane’s 2023 harvest exceeded 2 billion metric tonnes, making it a major crop by annual production. That harvest figure is not the same as the total mass of all living sugar cane at one time.
Could a bacterium outweigh the tree candidates?
The report says this possibility cannot be ruled out because some bacteria live in difficult-to-study aquifers and seafloor sediments. It offers no global species-level bacterial estimate that confirms such a winner.
Why do biomass figures use carbon mass?
Carbon mass measures the carbon contained in organisms and supports comparisons of how biological material is distributed through the biosphere. It is smaller than whole-organism weight and should not be compared directly with wet-mass totals.
Source: hn
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