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Housing Age and Affluence Influence Plant and Soil Nitrogen and Carbon Cycles in Two Semiarid Cities
Author(s) -
Cobley L. A. E.,
Pataki D. E.,
McCarthy H. R.,
Martin S. A.,
Ehleringer J. R.
Publication year - 2018
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2018jg004424
Subject(s) - metropolitan area , nitrogen , vegetation (pathology) , environmental science , isotopes of nitrogen , stable isotope ratio , geography , chemistry , medicine , physics , archaeology , organic chemistry , pathology , quantum mechanics
While human activities have altered the urban nitrogen (N) and carbon (C) cycles, the relationships between social and biophysical processes in cities are not well understood. Here we evaluated relationships between sociodemographic variables (median household income and housing age) and N and C contents and stable isotope ratios of vegetation in the Los Angeles Metropolitan Area (LA), California, and the Salt Lake Valley, Utah. We hypothesized that (1) N content and stable isotope ratios would be negatively related to income via increased N deposition in lower‐income areas; (2) N and C content and N stable isotope ratios would have a positive relationship with age due to soil organic matter accumulation and increased exposure to N losses over time, respectively; and (3) δ 13 C would increase with income as a result of increased fossil fuel‐derived CO 2 concentrations in lower‐income areas. We found that δ 15 N values decreased with median household income in both cities and N content decreased with income in LA. In addition, atmospheric NO 2 concentrations decreased with income in LA. Soil N and C content increased with housing age. However, δ 15 N had opposing relationships with age in the two cities. Finally, foliar δ 13 C values were more isotopically depleted with both increasing household income and increasing NO 2 concentrations in LA. These results show that urban foliar and soil isotopic composition are associated with sociodemographic variables and that affluence, as well as housing age, influences urban plant and soil function.