Earth greening affects carbon uptake by plants

Researchers from North Carolina State University recently published a paper which suggests that “greening” – the amount of leaves that plants can produce – will significantly impact how much carbon dioxide plants can capture and store.

“As we work to anticipate the future climate, a big question is: What’s going to happen to vegetation, one of the largest stores of carbon on Earth? We know temperatures will rise and the growing season will be longer in most places, but there are a lot of unknowns about how that will affect how carbon is cycled between plants and the atmosphere. Our new results allow us to be more confident about what those changes will be,” said study co-author Josh Gray. 

Although climate change has led to more greening in some areas, it leaves other places vulnerable to “browning.” This process is caused by high temperatures which negatively impact photosynthesis and promote more carbon release.

“An earlier spring might be good for plant productivity because you have a longer period of carbon uptake,” said study first author Xiaojie Gao. “However, a longer autumn might make the situation worse. In autumn, plants tend to emit carbon.”

The researchers used satellites that measured infrared light to determine leaf biomass.

“Healthy green leaves are sort of like infrared mirrors,” said Gray. “So, they look really ‘bright’ to satellites in these wavelengths. With a few tricks, we can calculate an index that is the combination of how bright a place is in infrared and red wavelengths, and corresponds to how many leaves are in a place.”

The experts discovered that leaf biomass might have a larger impact on carbon uptake than the length of the growing season.

“There are some places where we have more leaves than we used to have, particularly at the higher latitudes,” Gray said. “There are also some places where spring might be coming early, and fall might be coming late. These changes are all affecting the amount of photosynthesis that is going on, but the amount of leaves plants are producing has a stronger association with carbon uptake than changes in growing season length. In other words, we found that greening trends were more important pound for pound than an extension in the growing season for carbon uptake.”

The research team believes satellites will play an essential role in future research and hope their research will help inform climate predictions.

The study is published in the journal Global Biogeochemical Cycles.

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By Erin Moody, Earth.com Staff Writer

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