Influence of aboveground tree biomass, home age, and yard maintenance on soil carbon levels in residential yards

摘要

With the rapid urbanization of natural lands, researchers have begun to examine the capacity of urban soils to store carbon (C), with recent attention to residential yards. We performed a case study to examine four potential influences on soil C levels in residential yards. In 67 yards containing trees, we examined the relationship of soil C (kg m~(-2)) to tree aboveground biomass, home age (3-87 years), yard maintenance (fertilization, irrigation, mulching or bagging lawn clippings), and soil texture (% clay, % sand, % silt), at three depths (0-15 cm, 15-30 cm, and 30-50 cm). Six tree aboveground biomass data sets were developed: 1) biomass, 2) biomass~*(1/distance from tree), 3) biomass≤15 m from sample site, 4) biomass≤10 m, 5) biomass≤5 m, and 6) biomass≤4 m. Biomass≤5 m and biomass≤4 m had the greatest explanatory power for soil C at 30-50 cm depth (P=0.001, R~2=0.28; P=0.05 R~2=0.39, respectively). The relationship between soil C and home age was positive at 0-15 cm (P=0.0003, R~2=0.19), but constant at the two lower depths. Yard maintenance had no significant influence on soil C levels across home age. At 0-15 cm, soil C increased with % silt (P=0.006, R~2=0.12). Overall, trees in turfgrass yards may have a stabilizing effect on soil C levels below 15 cm but minimal influence above 15 cm.