Long-Term Nitrogen Addition Does Not Increase Soil Carbon Storage or Cycling Across Eight Temperate Forest and Grassland
- PDF / 473,189 Bytes
- 14 Pages / 593.972 x 792 pts Page_size
- 24 Downloads / 207 Views
Long-Term Nitrogen Addition Does Not Increase Soil Carbon Storage or Cycling Across Eight Temperate Forest and Grassland Sites on a Sandy Outwash Plain Clare E. Kazanski,1*
Charlotte E. Riggs,1 Peter B. Reich,2,3 and Sarah E. Hobbie1
1 Department of Ecology, Evolution, and Behavior, University of Minnesota, 1479 Gortner Ave., St. Paul, Minnesota 55108, USA; Department of Forest Resources, University of Minnesota, 1530 Cleveland Ave. N., St. Paul, Minnesota 55108, USA; 3Hawkesbury Institute for the Environment, Western Sydney University, Penrith South DC, NSW 2751, Australia
2
ABSTRACT Experimental nitrogen (N) deposition generally inhibits decomposition and promotes carbon (C) accumulation in soils, but with substantial variation among studies. Differences in ecosystem properties could help explain this variability: N could have distinct effects on decomposition and soil C due to differences in vegetation characteristics (that is, root C inputs and chemistry) that influence microbial biomass or soil properties like pH that can affect organic matter stabilization. We used a 12-year N addition experiment to determine effects of sustained N addition on soil C pool sizes and cycling across different grassland, conifer and
Received 8 May 2018; accepted 2 February 2019 Electronic supplementary material: The online version of this article (https://doi.org/10.1007/s10021-019-00357-x) contains supplementary material, which is available to authorized users. Author Contributions CEK and SEH conceived study, CEK performed the research and analyzed the data, CEK, CER, PBR, and SEH all contributed to interpretation and framing, CEK wrote the first paper version, CEK, CER, PBR, and SEH all contributed to paper revisions. Data available at eriment?e145.
http://www.cedarcreek.umn.edu/research/data/exp
*Corresponding author; e-mail: [email protected]
deciduous forest sites in Minnesota, USA, while controlling for soil type and climate. We conducted a year-long soil incubation, and fit one- and twopool decay models to respiration data to identify C pool sizes and decay rates. Contrary to previous studies, we found no consistent effects of N on soil C across sites: soil C stocks, microbial respiration, soil C decay rates and pool sizes all showed no general response to N in these sandy soils. Nevertheless, microbial biomass, microbial respiration, and the root biomass C pool responses to N addition were highly correlated, suggesting that soil C responses were ultimately driven by fine root biomass C responses to N addition, which in turn affected microbial biomass. However, the inconsistent directional responses to N among sites with similar vegetation cover highlight that N addition effects can be site-specific and raise caution for broad extrapolation of results from individual systems to global models. Key words: soil organic matter; decomposition; microbial respiration; nitrogen deposition; fertilization; soil carbon; incubation.
C. E. Kazanski and others
HIGHLIGHTS Across forest and grassland sites, soil C did not res
Data Loading...
