The common landscaping practice of mulching under and around plant material to conserve water, help maintain consistent substrate temperatures, and as a weed inhibitor, can also play a role in carbon sequestering and global warming. Of the variety of mulches used in landscape maintenance, the most important and least used is litter from the landscape itself. The biomass generated by trees, shrubs, perennials, and ground covers (high in Carbon content) is typically blown off and hauled away, adding unnecessary expense to usually tight maintenance budgets. If the collected plant litter is placed in landfill sites, then the 45%-50% of carbon contained in the material is slowly converted to methane gas (Smith and Heath). Methane gas is 23 times more potent than CO2 as a greenhouse gas (Keppler and Rockmann 54). Alternatively, if plant litter is left in place then the carbon it contains is sequestered for extensive periods of time while the material decomposes and is absorbed by the soil (Hu). In addition, while covering the soil surface, plant litter slows down emissions of CO2 from the soil to the atmosphere (Si-Qing et al).
We recommend in our maintenance specifications to leave all but large, hazardous, and unsightly plant litter in place to help establish a sustainable nutrient cycle.
Keppler, F. and Rockmann, T. 2007. Methane Plants and Climate Change. Scientific American, February.
Hu, Shuijin 2001. Nitrogen limitation of microbial decomposition in a grassland under elevated CO2. Nature, January/409. 188-191.
Si-Qing, C., Xiao-Yong, C., Guang-Sheng, Z., and Ling-Hao, L. Study on the CO2 release rate of soil respiration and litter decomposition in Stipa grandis Steppe in Xilin River Basin, Inner Mongolia. Journal of Integrative Plant Biology.