Higher temperatures cut carbon exudation from the roots of two common tree species
Higher temperatures drove down how much carbon the roots of two common tree species exude, a Dartmouth-led New Phytologist study found. Lead author Thomas Muratore expects exudation to fall wherever temperatures rise and soil nitrogen does not.
The Scientist · Science desk
Two tree species' roots: warming drove exudation down, root size and shape unchanged. Added nitrogen raised it regardless of temperature. Exudation feeds soil microbes that free nutrients. Where temperatures rise but nitrogen doesn't, Muratore expects less exudation. The team expected a rise.
- Who's exposed exposure Roots of the two tree species Higher temperatures drove down exudation; root system size and shape did not change at all, claim 5
- Who's exposed exposure Same roots, with added nitrogen Increased nitrogen levels increased exudation, regardless of temperature, Muratore said, claim 6
- Who's exposed exposure Soil microbes Exuded carbon compounds feed them and make them more active; they break down soil, freeing nutrients for roots, claim 2
- What it costs cost Where temperatures rise alone Muratore says exudation will likely decrease where nitrogen doesn't rise, and plant-soil interaction will decline, claim 8
- What doesn't add up contradiction Muratore and collaborators Expected warming and nitrogen to raise exudation across the board; they were wrong, claim 4
| Who | How | Kind | Claim |
|---|---|---|---|
| Roots of the two tree species | Higher temperatures drove down exudation; root system size and shape did not change at all | exposure | 5 |
| Same roots, with added nitrogen | Increased nitrogen levels increased exudation, regardless of temperature, Muratore said | exposure | 6 |
| Soil microbes | Exuded carbon compounds feed them and make them more active; they break down soil, freeing nutrients for roots | exposure | 2 |
| Where temperatures rise alone | Muratore says exudation will likely decrease where nitrogen doesn't rise, and plant-soil interaction will decline | cost | 8 |
| Muratore and collaborators | Expected warming and nitrogen to raise exudation across the board; they were wrong | contradiction | 4 |
What happened
- The study put two common tree species under higher temperatures and higher soil nitrogen, two changes that climate change can bring.
- Muratore and his collaborators had expected warming and added nitrogen to raise exudation across the board, and they were wrong.
- Added soil nitrogen increased exudation regardless of temperature, Muratore said.
- A companion paper in Scientific Data describes a database of more than 10,000 plant species and their belowground traits.
Why it matters
- What it limits constraint The step from lower exudation to slower nutrient release is the researchers' projection from how exudation feeds soil microbes.
- What it sets up precedent The expectation that warming speeds belowground activity, an assumption this team itself held, now has a counterexample in two tree species.
- What's now possible capability Because the trait database is public, other groups can test exudation against cloning and other belowground strategies without building their own dataset.
Exudation is the release of soluble carbon compounds from root tips. Microbes in the surrounding soil feed on it and become more active, and they break down the soil so that more nutrients are available for roots to absorb [2]. Scientists are beginning to understand the basics, but how climate change affects the process is still an open question [9].
Thomas Muratore, a postdoctoral researcher in Shersingh Joseph Tumber-Dávila's lab, is first author of the study [1]. Root size and shape did not change at all [5]. In our view, that means the simplest explanation for the drop, that warmed trees grew less root, does not fit these two species.
The net effect at a given site therefore depends on which driver arrives. Muratore said: "But we're unlikely to see nitrogen levels go up everywhere." [7] He described the consequence for soil as a loss in warmer places without added nitrogen, and said "that means the dynamic interaction between plants and soil in those places will decline" [8].
Phys.org's account of the study does not give the size of the effect, the two species, the amount of warming applied, how many trees were measured, or whether they grew in a field or a greenhouse. A projection to every place where temperatures rise depends on those details.
Two companion papers take a wider view. A New Phytologist concept paper led by Tumber-Dávila uses the global data set to call for studying root traits together [11]. "People who study roots need to talk with the people who study clonality, and so on," he said [12]. Clonality is a strategy in which underground stems become genetic copies of the original plant [13].
Muratore adds a geographic caveat. Most of what scientists know about root systems comes from the U.S. and Europe [14]. "We can't have a thorough understanding of plant systems and strategies if we aren't looking at plant systems and strategies globally," he said [15].
What to watch
- Whether the full New Phytologist paper gives the species, the amount of warming and the size of the exudation drop.
- Studies that measure microbial activity and nutrient availability alongside exudation under warming, which would test the link the researchers describe.
- Root work from outside the U.S. and Europe, which Muratore says is needed.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence50
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Claim ledger
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- [1]
Thomas Muratore is first author of a new study published in New Phytologist and a postdoctoral researcher in the lab of Shersingh Joseph Tumber-Dávila, an assistant professor in Dartmouth's Department of Environmental Studies.
- [2]
Exudation occurs when plants release soluble carbon compounds from the tips of their roots; this feeds microbes in the surrounding soil, making them more active, and those microbes break down the soil, which makes more nutrients available for the roots to absorb.
- [3]
Muratore's study examined how two common tree species respond to higher temperatures and to higher amounts of nitrogen in the soil, both of which can be byproducts of climate change.
- [4]
Muratore and his collaborators thought warming and nitrogen addition would both increase all kinds of plant activity, so exudation would increase across the board, but they were wrong.
- [5]
The researchers found that the size and shape of the root systems did not change at all, and that higher temperatures drove down exudation.
- [6]
Muratore said: "Increased nitrogen levels increased exudation, regardless of temperature."
- [7]
Muratore said: "But we're unlikely to see nitrogen levels go up everywhere."
- [8]
Muratore said exudation will likely decrease in places where temperatures go up but nitrogen levels don't, "and that means the dynamic interaction between plants and soil in those places will decline."
- [9]
How climate change might affect exudation is still an open question, with consequences for both plants and soil; scientists are beginning to understand the basics of exudation.
- [10]
Tumber-Dávila is co-author of a paper in Scientific Data describing a new database of more than 10,000 plant species, containing every measurable trait the authors could think of associated with belowground strategies.
- [11]
Using the new global data set, Tumber-Dávila led a concept paper in New Phytologist that calls on researchers to study belowground traits together rather than in isolation; the database has been made publicly available.
- [12]
Tumber-Dávila said: "People who study roots need to talk with the people who study clonality, and so on."
- [13]
Cloning is an underground behavior in which underground stems become genetic copies of the original plant.
- [14]
Some underground traits are more common in certain parts of the world and researchers tend to study them where they are common; most of what scientists know about root systems comes from work in the U.S. and Europe.
- [15]
Muratore said: "We can't have a thorough understanding of plant systems and strategies if we aren't looking at plant systems and strategies globally."
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Sources
1 independent publisher whose own reporting we read for this story.
- phys.orgClimate warming can slow how tree roots feed soil microbes
1 article · October 16, 2026
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