Plant nitrogen concentration and isotopic composition in residential lawns across seven US cities
- 545 Downloads
Human drivers are often proposed to be stronger than biophysical drivers in influencing ecosystem structure and function in highly urbanized areas. In residential land cover, private yards are influenced by individual homeowner preferences and actions while also experiencing large-scale human and biophysical drivers. We studied plant nitrogen (%N) and N stable isotopic composition (δ15N) in residential yards and paired native ecosystems in seven cities across the US that span major ecological biomes and climatic regions: Baltimore, Boston, Los Angeles, Miami, Minneapolis-St. Paul, Phoenix, and Salt Lake City. We found that residential lawns in three cities had enriched plant δ15N (P < 0.03) and in six cities higher plant N (%) relative to the associated native ecosystems (P < 0.05). Plant δ15N was progressively depleted across a gradient of urban density classes in Baltimore and Boston (P < 0.05). Lawn fertilization was associated with depleted plant δ15N in Boston and Los Angeles (P < 0.05), and organic fertilizer additions were associated with enriched plant δ15N in Los Angeles and Salt Lake City (P < 0.04). Plant δ15N was significantly enriched as a function of housing age in Baltimore (r 2 = 0.27, P < 0.02), Boston (r 2 = 0.27, P < 0.01), and Los Angeles (r 2 = 0.34, P < 0.01). These patterns in plant δ15N and plant N (%) across these cities suggests that N sources to lawns, as well as greater rates of N cycling combined with subsequent N losses, may be important drivers of plant N dynamics in lawn ecosystems at the national scale.
KeywordsUrban ecology Natural abundance nitrogen stable isotopes Ecological convergence Nitrogen cycling
The authors thank Meghan Avolio, La’Shaye Ervin, William Borrowman, Moumita Kundu, and Barbara Uhl for field and laboratory assistance. This research was funded by a series of collaborative grants from the US National Science Foundation (EF-1065548, 1065737, 1065740, 1065741, 1065772, 1065785, 1065831, 121238320).
Author contribution statement
T. L. E. T. conducted laboratory and fieldwork, analyzed the data and wrote the manuscript. D. E. P., J. C.-B., P. M. G., S. J. H., J. B. H., S. E. H., C. N., and K. C. N. formulated the idea and developed methodology. J. L. M. conducted fieldwork. All authors provided editorial advice.
- Bissonette JA (1999) Small sample size problems in wildlife ecology: a contingent analytical approach. Wildl Biol 5:65–71Google Scholar
- Claritas (2008) PRIZM segment narratives. Nielsen (US) www.claritas.com/MyBestSegments/Default.jsp. Accessed 15 Nov 2014
- Craine JM, Elmore AJ, Aidar MPM, Bustamante M, Dawson TE, Hobbie EA, Kahmen A et al (2009) Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability. New Phytol 183:980–992CrossRefPubMedGoogle Scholar
- Gold AJ, Deragon WR, Sullivan WM, Lemunyon JL (1990) Nitrate-nitrogen losses to groundwater from rural and suburban land uses. J Soil Water Conserv 45:305–310Google Scholar
- Groffman PM, Law NL, Belt KT, Band LE, Fisher GT (2004) Nitrogen fluxes and retention in urban watershed ecosystems. Ecosystems 7:393–403Google Scholar
- Harrell FE, Dupont C et al (2014) Misc: Harrell miscellaneous. R package version 3.14-5. http://CRAN.R-project.org/package=Hmisc. Accessed 6 Nov 2014
- National Climatic Data Center (NCDC) (2014) National oceanic and atmospheric administration (NOAA) satellite and information service. 1981–2010 Climate normals. http://www.ncdc.noaa.gov/. Accessed 27 Feb 2015
- Pohlert T (2014) The pairwise multiple comparison of mean ranks package (PMCMR). R package. http://ftp.ussg.iu.edu/CRAN/. Accessed 28 Oct 2014
- Pouyat RV, Groffman PM, Yesilonis I, Hernandez L (2003) Soil carbon pools and fluxes in urban ecosystems. In: Kimble JM, Heath LS, Birdsey RA, Lal R (eds) The potential of US forest soils to sequester carbon and mitigate the greenhouse effect. CRC, Boca Raton, pp 347–362Google Scholar
- R Core Team (2013) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. http://www.R-project.org/. Accessed 20 Oct 2014
- US Census Bureau (2010) Annual estimates of the resident population: April 1, 2010 to July, 2013. Source: US Census Bureau, Population Division. Release date: March 2014. http://www.census.gov/population/metro/data/index.html. Accessed 24 Oct 2014
- US Geological Survey (USGS) (2008) USGS global ecosystems data viewer. http://rmgsc.cr.usgs.gov/ecosystems/dataviewer.shtml. Accessed 24 Oct 2014