Centre for Urban Greenery and Ecology, National Parks Board, Singapore.
Department of Geography, National University of Singapore, Singapore.
J Environ Manage. 2021 Feb 15;280:111752. doi: 10.1016/j.jenvman.2020.111752. Epub 2020 Dec 24.
Turfgrass is an important component of the urban landscape frequently considered as an alternative land cover to offset anthropogenic CO emissions. However, quantitative information of the potential to directly remove CO from the atmosphere by turfgrass systems is lacking, especially in the tropics. Most assessments have considered the carbon accumulated by grass shoots and soil, but not the release of CO to the atmosphere by soil respiration (i.e., soil CO efflux). Here, we measured at high-temporal resolution (30-min) soil CO efflux, production, and storage rate for nearly three years in a residential lawn of Singapore. Furthermore, we quantified the carbon capture related to biomass production and CO emissions from fossil fuel consumption associated with maintenance activities (e.g., mowing equipment). Warm and humid conditions resulted in relatively constant rates of soil CO efflux, CO storage in soil, and aboveground biomass production (3370, 652, 1671 Mg CO km yr; respectively), while the systematic use of mowing machinery emitted 27 Mg CO km yr. Soil CO efflux and CO mowing emissions represent carbon losses to the atmosphere, while CO storage in soil and biomass productivity represent gains of carbon into the ecosystem. Under a steady state in which soil CO losses are only compensated by atmospheric CO uptake by photosynthesis, an ideal clipping waste disposal management, in which no CO molecule returns to the atmosphere (i.e., clippings are not burnt), and a 3-week mowing regime, this site can act as a sink of 2296 Mg CO km yr. In the scenario of incinerating all clippings, the lawn acts as an emission source of 1046 Mg CO km yr. Thus, management practices that reduce mowing frequency together with clipping disposal practices that minimize greenhouse gas emissions are needed to make urban lawns a potential natural solution to mitigate global environmental change.
草坪是城市景观的重要组成部分，常被视为抵消人为 CO 排放的替代土地覆盖物。然而，缺乏有关草坪系统直接从大气中去除 CO 的潜力的定量信息，尤其是在热带地区。大多数评估都考虑了草茎和土壤中积累的碳，但没有考虑土壤呼吸（即土壤 CO 通量）向大气中释放的 CO。在这里，我们在新加坡的一个住宅草坪上进行了近三年的高时间分辨率（30 分钟）土壤 CO 通量、产生和储存率的测量。此外，我们量化了与生物量生产和与维护活动（如剪草设备）相关的化石燃料消耗有关的 CO 排放相关的碳捕获。温暖潮湿的条件导致土壤 CO 通量、土壤中 CO 储存和地上生物量生产的相对恒定速率（分别为 3370、652 和 1671 Mg CO km yr），而系统使用剪草机排放了 27 Mg CO km yr。土壤 CO 通量和 CO 剪草排放代表碳向大气中的损失，而土壤中 CO 储存和生物量生产力则代表碳进入生态系统的增益。在土壤 CO 损失仅由光合作用吸收大气 CO 来补偿的稳定状态下，理想的剪草废物处理管理（即不将 CO 分子返回大气中，即不燃烧草屑）和 3 周的剪草制度下，该地点每年可吸收 2296 Mg CO km yr。在将所有草屑焚烧的情况下，草坪成为每年 1046 Mg CO 的排放源。因此，需要减少剪草频率的管理实践以及最大限度减少温室气体排放的草屑处置实践，以使城市草坪成为缓解全球环境变化的潜在自然解决方案。
