Methane Uptake in Urban Forests and Lawns

作者：Groffman Peter M^*; Pouyat Richard V

来源：Environmental Science & Technology, 2009, 43(14): 5229-5235.

DOI：10.1021/es803720h

The largest natural biological sink for the radiatively active trace gas methane (CH(4)) is bacteria in soils that consume CH4 as an energy and carbon source. This sink has been shown to be sensitive to nitrogen (N) inputs and alterations of soil physical conditions. Given this sensitivity, conversion of native ecosystems to urban, suburban, and exurban managed lawns thus has potential to affect regional CH4 budgets. We measured CH(4) fluxes monthly from four urban forest four rural forest and four urban lawn plots in the Baltimore, MD, metropolitan area from 2001 to 2005. Our objectives were to evaluate the effects of urban atmospheric and land use change on CH(4) uptake and the importance of these changes relative to other greenhouse forcings in the urban landscape. Rural forests had a high capacity for CH(4) uptake (1.68 mg m(-2) day(-1)). This capacity was reduced in urban forests (0.23 mg m(-1) day(-1)) and almost completely eliminated in lawns. Possible mechanisms for these reductions include increases in atmospheric N deposition and CO(2) levels, fertilization of lawns, and alteration of soil physical conditions that influence diffusion. Although conversion of native forests to lawns had dramatic effects on CH(4) uptake, these effects do not appear to be significant to statewide greenhouse gas forcing.

• 出版日期2009-7-15