It is often said that forests are the lungs for Earth. Tall trees reach skyward in search of sunlight, sucking up water from their roots and carbon dioxide through their leaves. Photosynthesis.
The photosynthetic machinery in trees can breakdown if temperatures are too high.
A new study, which combined tree canopy measurements with global satellite data, found that a small portion of canopy leaves within tropical forests may be nearing their limit.
The study by Gregory Goldsmith, a tropical ecologist at Chapman University (California), shows that tropical forest leaves can exceed their critical temperatures thresholds.
Research shows tropical trees can keep photosynthesizing up to 46.7 °C (116 °F) on average. The world’s temperature is not uniform, and neither are forest canopies. Heat tolerance can vary.Goldsmith states that the differences in species and populations may even be found within individual leaves.
NASA’s Earth Observatory data was used by a team of ecoinformaticians led by Christopher Doughty, from Northern Arizona University to understand if certain leaves are approaching temperatures that are too warm for photosynthesis. ECOSTRESS sensorThe International Space Station has a satellite that measures the temperature of land surfaces as it orbits Earth.
The satellite measurements between 2018 and 2021 were validated by data from tower-mounted temperature sensors that recorded temperatures in the canopy of five forest sites located in Brazil, Puerto Rico Panama and Australia.
Goldsmith says that “you need to use both ground-based and satellite-based measurements in order to understand the temperatures” of the tropical forest canopy. “Because for leaf temperatures, the averages are not as important as the extremes.”
The analysis found canopy temperatures peaked around 34 °C on average during dry periods, though some leaves exceeded 40 °C (104 °F). A small fraction of all leaves – about 0.01 percent – surpassed critical temperatures at least once a season.
The researchers said that extreme temperatures can have a dramatic effect on a plant’s physiology, even though they are not common. They describe it as a rare but high-impact event. You can also write on paper.
As temperatures rise, trees will close their stomata or bean-shaped holes on the leaves to conserve moisture. Doing so could cause the leaves to be exposed to damaging temperatures, as they are no longer able cool down by transpiration.
Water-stressed plants may experience increased heat in times of drought, when the soils become parched. Soil moisture can also affect canopy leaf temperature.
Goldsmith admits that we do not know much about the causes of tree death. Goldsmith says that we have a limited understanding of the interactions between heat, drought, temperature and water.
To simulate future conditions the team modeled tropical forest responses to warmer temperatures and periods of drought, using data collected from three warming experiments, in which temperature sensors had been taped onto individual leaves within the upper canopy.
The model simplifies forest dynamics by making a number of assumptions. However, simulations indicate that under future warming scenarios, up to 1,4% of upper canopy leaves could become too hot for photosynthesizing.
If warming exceeds 3.9 °C, which is possible under worst-case scenarios, it might be hotter than forests can withstand. Trees and leaves could start to die off, causing a large loss in carbon storage.
The researchers emphasize, however, that the results are uncertain, meaning we could still act to protect tropical rainforests by reducing emissions or curbing deforestation.
“It’s still in our hands to decide what happens to these vital realms like carbon, water and biodiversity,” You can also find out more about the following:.
The study was published in Nature.
