Ecosystem Carbon Storage Along a 100-Year Chronosequence of Suburban Households.

Land use change, such as the conversion of native landscapes to agriculture, generally results in net loss of soil organic matter and soil carbon pools, whereas abandonment of agricultural lands leads to gradual recovery of pre-agricultural soil carbon levels. Urban landscapes are among the most heavily managed land cover types, and their extent is also rapidly changing. However, little is known about the potential for soils underlying suburban residential areas to recover their native soil organic matter levels over time. An understanding of the effects of urban and suburban development on soil carbon storage will enable more accurate estimates of the carbon balance of urban ecosystems and could inform the design of best management practices for urban regions.

Our study of 44 household landscapes in the Minneapolis-Saint Paul, Minnesota metropolitan region showed high variability in soil carbon density across landscapes ranging in age from 5 to 100 years since development. Analyses of soil samples collected to 40 cm depth in lawn areas showed a pattern of increasing soil carbon density for house ages from 10 to 70 years since development. Soil carbon density in turfgrass lawns was consistently higher than in adjacent unmanaged grasslands and comparable to literature values for turfgrass lawns measured elsewhere. Here we will compare the rate of carbon accumulation in our sites to a chronosequence of abandoned agricultural fields in the same local area. Furthermore, we will examine the factors besides time since development that may have influenced the patterns of carbon storage and discuss implications of this analysis for developing urban ecosystem carbon budgets.