Novel strategies to mitigate GHG emissions from urban forestry waste

城市化影响了近1.0×10^6平方公里2，预计到2050年，全球约68%的人口将居住在城市地区。城市地区现在被公认为温室气体(GHG)排放的热点地区，占全球估计温室气体排放总量的一半以上。虽然建筑环境和交通部门的能源使用在排放中占主导地位，但城市废流和土壤的直接温室气体排放也是大的、但解决不好的贡献者；此外，城市土地使用可以极大地改变能源需求--例如，城市树木可以缓解城市热岛效应，从而减少能源消耗。拟议的项目将提供数据，以便更好地量化加拿大三个主要城市地区的城市林业废物在处理地点和用作覆盖物时的温室气体排放量。我们最近在经营林业的原木加工场地进行的研究表明，大量甲烷排放与林业废物有关。减少甲烷排放的目标很重要，因为甲烷占人为气候强迫的约30%，而且大气半衰期很短。这项研究将研究通过将城市林业废物转化为热解有机物(生物炭)来缓解该部门的温室气体排放，重点是在城市土壤和绿色基础设施中使用生物碳，以加强碳固存，减少基质温室气体排放(特别是甲烷)，并提高城市植被的生长和生理性能。我们还将与合作伙伴合作，研究在城市林业和城市绿色基础设施背景下使用创新的生物炭产品，包括颗粒生物炭和生物炭海岸种子。该项目的整合、建模和生命周期分析部分将探讨采用新战略产生“良性循环”的潜力，在这种循环中，来自城市植被的废物作为生物炭回收，用于城市林业和绿色基础设施，并带来包括减少城市能源需求在内的连锁反应。

Urbanization affects close to 1.0 x 10^6 km^2 with ~68% of the global population expected to reside in urban areas by 2050. Urban areas are now recognized as hotspots for greenhouse gas (GHG) emissions, accounting for more than half of total estimated GHG emissions globally. While energy use of the built environment and transportation sectors dominates emissions, direct GHG emissions from urban waste streams and soils are also large but poorly resolved contributors; moreover, urban land use can substantially modify energy demand - for example urban trees can mitigate the urban heat island effect and thus reduce energy use. The proposed project will provide data to better quantify GHG emissions from urban forestry waste at processing sites and when used as mulch in three major urban areas in Canada. Our recent studies in log processing sites in operational forestry suggest that large methane emissions are associated with forestry waste material. Targeting reductions in methane emissions is important as methane accounts for ~30% of anthropogenic climate forcing and has a short atmospheric half-life. The study will examine mitigation of GHG emission in this sector through conversion of urban forestry waste to pyrolyzed organic matter (biochar), with a focus on biochar use in urban soils and green infrastructure to enhance C sequestration, reduce substrate GHG emissions (particularly of methane), and increase urban vegetation growth and physiological performance. In collaboration with partners, we will also examine use of innovative biochar-based products, including pelletized biochars and biochar-coasted seeds, in an urban forestry and urban green infrastructure context. Integration, modeling, and life-cycle analysis components of the project will address the potential for novel strategies to generate a "virtuous cycle" in which waste material from urban vegetation is recycled as biochar for use in urban forestry and green infrastructure, with knock-on benefits that include reduced urban energy demand.