title: Multi-scale heterogeneity in vegetation and soil carbon in exurban residential land of southeastern Michigan, USA.
abstract: Exurban residential land (one housing unit per 0.2-16.2 ha) is growing in importance as a human-dominated land use. Carbon storage in the soils and vegetation of exurban land is poorly known, as are the effects on C storage of choices made by developers and residents. We studied C storage in exurban yards in southeastern Michigan, USA, across a range of parcel sizes and different types of neighborhoods. We divided each residential parcel into ecological zones (EZ) characterized by vegetation, soil, and human behavior such as mowing, irrigation, and raking. We found a heterogeneous mixture of trees and shrubs, turfgrasses, mulched gardens, old-field vegetation, and impervious surfaces. The most extensive zone type was turfgrass with sparse woody vegetation (mean 26% of parcel area), followed by dense woody vegetation (mean 21% of parcel area). Areas of turfgrass with sparse woody vegetation had trees in larger size classes (> 50 cm dbh) than did areas of dense woody vegetation. Using aerial photointerpretation, we scaled up C storage to neighborhoods. Varying C storage by neighborhood type resulted from differences in impervious area (8-26% of parcel area) and area of dense woody vegetation (11-28%). Averaged and multiplied across areas in differing neighborhood types, exurban residential land contained 5240 ± 865 g C/m2in vegetation, highly sensitive to large trees, and 13 800 ± 1290 g C/m2in soils (based on a combined sampling and modeling approach). These contents are greater than for agricultural land in the region, but lower than for mature forest stands. Compared with mature forests, exurban land contained more shrubs and less downed woody debris and it had similar tree size-class distributions up to 40 cm dbh but far fewer trees in larger size classes. If the trees continue to grow, exurban residential land could sequester additional C for decades. Patterns and processes of C storage in exurban residential land were driven by land management practices that affect soil and vegetation, reflecting the choices of designers, developers, and residents. This study provides an example of human-mediated C storage in a coupled human-natural system.
authors.affiliation: School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan, 48109, USA.
authors.forename: William S
authors.initials: WS
authors.lastname: Currie
authors.affiliation: School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan, 48109, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Kiger
authors.affiliation: School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan, 48109, USA.
authors.forename: Joan I
authors.initials: JI
authors.lastname: Nassauer
authors.affiliation: School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan, 48109, USA.
authors.forename: Meghan
authors.initials: M
authors.lastname: Hutchins
authors.affiliation: School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan, 48109, USA.
authors.forename: Lauren L
authors.initials: LL
authors.lastname: Marshall
authors.affiliation: School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan, 48109, USA.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Brown
authors.affiliation: Center for the Study of Complex Systems, University of Michigan, Ann Arbor, Michigan, 48109, USA.
authors.forename: Rick L
authors.initials: RL
authors.lastname: Riolo
authors.affiliation: Department of Geography and Environmental Management, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: Derek T
authors.initials: DT
authors.lastname: Robinson
authors.affiliation: School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan, 48109, USA.
authors.forename: Stephanie K
authors.initials: SK
authors.lastname: Hart
mesh_terms: D002244:Carbon / Q000737:chemistry*; D057486:Carbon Cycle; D004784:Environmental Monitoring; D006801:Humans; D008824:Michigan; D010944:Plants / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil; D002244:Carbon
keywords: carbon sequestration; carbon storage; exurban landscape; human-dominated landscape; landscape; land use; scaling; soils; spatial heterogeneity; tree cover; urban landscape