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Even trees 'hold their breath' to avoid harmful wildfire smoke, research finds By Mj Riches published July 31, 2024 Trees don't like to breathe wildfire smoke, either.Mixing volatile organic compounds, nitrogen oxides and sunlight will make ground-level ozone, which can cause breathing problems in humans.Unlike humans, however, leaves breathe in and out at the same time, constantly taking in and releasing atmospheric gases Clues from over a century of research In the early 1900s, scientists studying trees in heavily polluted areas discovered that those chronically exposed to pollution from coal- 2nd year Communication and expression techniques in English Babori.H burning had black granules clogging the leaf pores through which plants breathe.While scientists usually think about urban regions as being large sources of ozone that effect crops downwind, wildfire smoke is an emerging concern.For example, a study of multiple crop and wetland sites in California showed that smoke scatters light in a way that made plants more efficient at photosynthesis and growth.These pores are much like our mouths, except that while we inhale oxygen and exhale carbon dioxide, plants inhale carbon dioxide and exhale oxygen.When wildfire smoke is in the air, doctors urge people to stay indoors to avoid breathing in harmful particles and gases.They suspected that the substance in these granules was partly created by the trees, but due to the lack of available instruments at the time, the chemistry of those granules was never explored, nor were the effects on the plants' photosynthesis.It can also damage plants by degrading the leaf surface, oxidizing plant tissue and slowing photosynthesis.Other compounds, including nitrogen oxides, can also harm plants and reduce photosynthesis.We also measured the leaves' emissions of their usual volatile organic compounds and found very low readings.As atmospheric and chemical scientists, we study the air quality and ecological effects of wildfire smoke and other pollutants.Both humans and plants inhale other chemicals in the air around them and exhale chemicals produced inside them .However, a lab study in which plants were exposed to artificial smoke found that plant productivity dropped during and after smoke exposure -- though those plants did recover after a few hours.In a study that started quite by accident when smoke overwhelmed our research site in Colorado, we were able to watch in real time how the leaves of living pine trees responded.Plants have pores on the surface of their leaves called stomata.Most modern research into wildfire smoke's effects has focused on crops, and the results have been conflicting.On the first morning of heavy smoke, we did our usual test to measure leaf-level photosynthesis of Ponderosa pines.We were surprised to discover that the tree's pores were completely closed and photosynthesis was nearly zero.But what happens to trees and other plants that can't escape from the smoke?They may respond a bit like us, it turns out: Some trees essentially shut their windows and doors and hold their breath.How plants breathe?

Even trees 'hold their breath' to avoid harmful wildfire smoke,
research finds
By Mj Riches published July 31, 2024
Trees don't like to breathe wildfire smoke, either.
When wildfire smoke is in the air, doctors urge people to stay
indoors to avoid breathing in harmful particles and gases. But what
happens to trees and other plants that can't escape from the
smoke?
They may respond a bit like us, it turns out: Some trees essentially
shut their windows and doors and hold their breath.
As atmospheric and chemical scientists, we study the air quality
and ecological effects of wildfire smoke and other pollutants. In a
study that started quite by accident when smoke overwhelmed our
research site in Colorado, we were able to watch in real time how
the leaves of living pine trees responded.
How plants breathe?
Plants have pores on the surface of their leaves called stomata.
These pores are much like our mouths, except that while we inhale
oxygen and exhale carbon dioxide, plants inhale carbon dioxide and
exhale oxygen.
Both humans and plants inhale other chemicals in the air around
them and exhale chemicals produced inside them .
Unlike humans, however, leaves breathe in and out at the same
time, constantly taking in and releasing atmospheric gases
Clues from over a century of research
In the early 1900s, scientists studying trees in heavily polluted areas
discovered that those chronically exposed to pollution from coal-
2nd year Communication and expression techniques in English
Babori.H
burning had black granules clogging the leaf pores through which
plants breathe. They suspected that the substance in these granules
was partly created by the trees, but due to the lack of available
instruments at the time, the chemistry of those granules was never
explored, nor were the effects on the plants' photosynthesis.
Most modern research into wildfire smoke's effects has focused on
crops, and the results have been conflicting.
For example, a study of multiple crop and wetland sites in California
showed that smoke scatters light in a way that made plants more
efficient at photosynthesis and growth. However, a lab study in
which plants were exposed to artificial smoke found that plant
productivity dropped during and after smoke exposure — though
those plants did recover after a few hours.
Mixing volatile organic compounds, nitrogen oxides and sunlight will
make ground-level ozone, which can cause breathing problems in
humans. It can also damage plants by degrading the leaf surface,
oxidizing plant tissue and slowing photosynthesis.
While scientists usually think about urban regions as being large
sources of ozone that effect crops downwind, wildfire smoke is an
emerging concern. Other compounds, including nitrogen oxides,
can also harm plants and reduce photosynthesis.
On the first morning of heavy smoke, we did our usual test to
measure leaf-level photosynthesis of Ponderosa pines. We were
surprised to discover that the tree's pores were completely closed
and photosynthesis was nearly zero.
We also measured the leaves' emissions of their usual volatile
organic compounds and found very low readings. This meant that
the leaves weren't "breathing" — they weren't inhaling the carbon
2nd year Communication and expression techniques in English
Babori.H
dioxide they need to grow and weren't exhaling the chemicals they
usually release.
The long-term impact is still unknown
The jury is still out on exactly how long the effects of wildfire smoke
last and how repeated smoke events will affect plants — including
trees and crops — over the long term.
With wildfires increasing in severity and frequency due to climate
change, forest management policies and human behaviour, it's
important to gain a better understanding of the impact.