TY - JOUR
T1 - Cross-biome assessment of gross soil nitrogen cycling in California ecosystems
AU - Yang, Wendy H.
AU - Ryals, Rebecca A.
AU - Cusack, Daniela F.
AU - Silver, Whendee L.
N1 - Funding Information:
This research was funded by a grant from the Kearney Foundation to W. Silver as well as a National Science Foundation (NSF) (DEB-0808383) Doctoral Dissertation Improvement Grant to W. Yang. The Department of Energy Graduate Research Environmental Fellowship and the NSF Graduate Research Fellowship provided support for W. Yang. W. L. Silver was partially supported by the USDA National Institute of Food and Agriculture, McIntire Stennis project (CA-B-ECO-7673- MS). We appreciate lab assistance from Steve Blazewicz, Wendy Chou, Nicole Kim, Audrey Liu, Yit Teh, Andrew Thompson, Tana Wood, and Glen Yang. We thank Nicholas Krueger for producing the map of the study sites. We also thank the principal investigators for all of the research sites that we utilized: Edith Allen, Ronald Amundson, Dennis Baldocchi, Valerie Eviner, Michael Goulden, David Graber, Robert Graham, Brian Lanoil, Michael Loik, Diane Pataki, Katherine Purcell, James Richards, and David Smart. We also thank two anonymous reviewers for providing two rounds of rigorous and comprehensive reviews to improve our manuscript.
Publisher Copyright:
© 2017 Elsevier Ltd
PY - 2017/4/1
Y1 - 2017/4/1
N2 - Microbial transformations of nitrogen (N) largely determine whether N is retained in ecosystems via net primary productivity or lost via gaseous emissions and leaching. The controls on soil N cycling are often studied at single locales, making it difficult to predict N cycling at regional to global scales. We hypothesized that contemporary soil properties exhibit consistent relationships with instantaneous gross N cycling rates across diverse biomes that create a continuum in these properties. We measured ex situ gross N cycling rates and soil properties at 33 study sites representing five biome classifications in California including deserts, grasslands, shrublands, forest, and wetlands. Desert soils had significantly lower total N, organic carbon (C), microbial biomass N, and soil moisture as well as higher pH than all other biomes, whereas forests and wetlands had significantly lower soil nitrate (NO3−) concentrations (P < 0.001 for all). Gross mineralization rates were best predicted by the combination of soil moisture and soil C:N ratios (R2 = 0.46), which exerted positive and negative controls, respectively. Grasslands exhibited marginally higher gross mineralization than all other biomes, whereas deserts had the lowest rates due to low soil moisture (P = 0.09). Gross nitrification rates were positively correlated to soil NO3− concentrations (R2 = 0.34) and negatively correlated to soil C:N ratios (R2 = 0.31). The negative relationship between gross nitrification and soil C:N ratios was driven by forest soils, which had significantly higher C:N ratios and lower gross nitrification than all other biomes (P < 0.05). Dissimilatory NO3− reduction to NH4+ (DNRA) occurred in soils from all biomes. The strong positive correlation between DNRA rates and soil NO3− (R2 = 0.41) suggests NO3− limitation of DNRA. Predictable patterns in gross N cycling across biomes in California suggest that contemporary soil properties are important drivers of instantaneous soil N cycling rates that integrate over differences in vegetation type, atmospheric N deposition rates, and local climate.
AB - Microbial transformations of nitrogen (N) largely determine whether N is retained in ecosystems via net primary productivity or lost via gaseous emissions and leaching. The controls on soil N cycling are often studied at single locales, making it difficult to predict N cycling at regional to global scales. We hypothesized that contemporary soil properties exhibit consistent relationships with instantaneous gross N cycling rates across diverse biomes that create a continuum in these properties. We measured ex situ gross N cycling rates and soil properties at 33 study sites representing five biome classifications in California including deserts, grasslands, shrublands, forest, and wetlands. Desert soils had significantly lower total N, organic carbon (C), microbial biomass N, and soil moisture as well as higher pH than all other biomes, whereas forests and wetlands had significantly lower soil nitrate (NO3−) concentrations (P < 0.001 for all). Gross mineralization rates were best predicted by the combination of soil moisture and soil C:N ratios (R2 = 0.46), which exerted positive and negative controls, respectively. Grasslands exhibited marginally higher gross mineralization than all other biomes, whereas deserts had the lowest rates due to low soil moisture (P = 0.09). Gross nitrification rates were positively correlated to soil NO3− concentrations (R2 = 0.34) and negatively correlated to soil C:N ratios (R2 = 0.31). The negative relationship between gross nitrification and soil C:N ratios was driven by forest soils, which had significantly higher C:N ratios and lower gross nitrification than all other biomes (P < 0.05). Dissimilatory NO3− reduction to NH4+ (DNRA) occurred in soils from all biomes. The strong positive correlation between DNRA rates and soil NO3− (R2 = 0.41) suggests NO3− limitation of DNRA. Predictable patterns in gross N cycling across biomes in California suggest that contemporary soil properties are important drivers of instantaneous soil N cycling rates that integrate over differences in vegetation type, atmospheric N deposition rates, and local climate.
KW - Dissimilatory nitrate reduction to ammonium
KW - Gross nitrogen cycling
KW - Isotope pool dilution
KW - Nitrification
KW - Nitrogen
KW - Nitrogen mineralization
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U2 - 10.1016/j.soilbio.2017.01.004
DO - 10.1016/j.soilbio.2017.01.004
M3 - Article
AN - SCOPUS:85009260138
SN - 0038-0717
VL - 107
SP - 144
EP - 155
JO - Soil Biology and Biochemistry
JF - Soil Biology and Biochemistry
ER -