Novel Strategies to Mitigate Greenhouse Gas Emissions from Urban Forestry
——Biochar Application
Abstract
Urban land use currently impacts approximately 1.0 million km² of the Earth's surface, with around 57% of the global population residing in cities—a figure that rises to about 82% in Canada. As urban land use is expected to double by 2100, urban areas are increasingly recognized as significant contributors to global greenhouse gas (GHG) emissions, accounting for over half of total emissions worldwide. Notably, emissions from urban soils and waste streams are not well understood, though recent satellite observations have identified significant GHG emissions from these areas, underscoring the urgency of addressing urban emissions in climate mitigation strategies.
This study explores the use of biochar, pyrolyzed biomass intended for soil amendment, as a method for reducing GHG emissions and enhancing carbon sequestration in urban settings. Biochar is proposed to improve soil quality, increase nutrient availability, and boost microbial activity, offering a multifaceted approach to emission mitigation while supporting sustainable urban forestry.
Our findings reveal that increasing the application of biochar leads to a significant uptick in carbon dioxide (CO₂) absorption and a reduction in methane (CH4) emissions. We also observed a positive impact on the absorption of ammonium nitrogen, which may improve soil health. However, changes in tree growth metrics such as diameter at breast height and crown diameter, while positive, were not statistically significant.
In summary, integrating biochar into urban green infrastructure emerges as a viable strategy for leveraging urban forestry waste to enhance environmental quality and support urban sustainability efforts. While the study indicates that biochar can substantially influence GHG dynamics and certain soil properties, the impact on broader soil and plant health metrics within urban forestry remains inconclusive and suggests the need for further research. This positions biochar as a promising, yet not definitive, tool for enhancing urban ecosystems and contributing to the resilience and sustainability of urban environments in the face of climate change.
