Urban Tree Channeling of Soil Methane and Nitrous Oxide and Its Mitigation Using Biochar.
Karim MR, Thomas SC
Urban Ecology
The street trees outside your window may be quietly pumping invisible greenhouse gases skyward — and a simple soil amendment could shut that pipeline down.
Scientists discovered that trees in cities don't just absorb carbon dioxide — they can also act like chimneys, pulling harmful gases like methane and nitrous oxide up from wet, oxygen-poor soils and releasing them into the air. These gases are far more potent than CO2 at warming the planet. When researchers added biochar (a charcoal-like material made from burned organic matter) to the soil, the trees released much less of these gases, suggesting biochar could be a powerful tool for city planners and gardeners alike.
Key Findings
Urban trees actively channel methane and nitrous oxide from soil to atmosphere, acting as biological conduits for greenhouse gases beyond CO2.
Biochar soil amendment significantly reduced tree-mediated emissions of both methane and nitrous oxide in urban settings.
Urban tree greenhouse gas exchange is more complex than previously recognized, with non-CO2 gases potentially offsetting some of the carbon sequestration benefits of urban forests.
chevron_right Technical Summary
Urban trees act as conduits, channeling potent greenhouse gases — methane and nitrous oxide — from waterlogged soils through their trunks and into the atmosphere. Adding biochar to the soil around trees significantly reduces this gas leakage, offering a practical tool for making city forests better climate allies.
Abstract Preview
Urban forests are important carbon sinks; however, urban tree exchange of non-CO
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