TY - JOUR
T1 - Lorenz Curve and Gini Coefficient Reveal Hot Spots and Hot Moments for Nitrous Oxide Emissions
AU - Saha, Debasish
AU - Kemanian, Armen R.
AU - Montes, Felipe
AU - Gall, Heather
AU - Adler, Paul R.
AU - Rau, Benjamin M.
N1 - Funding Information:
The work was funded by the USDOT Sun-grant 52110-9601, the USDA AFRI grant 2012-68005-19703, and the Richard King Mellon Foundation. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer. All data are archived on Penn State Data Commons (doi:10.18113/D3ZQ0B).
Publisher Copyright:
©2018. The Authors.
PY - 2018/1
Y1 - 2018/1
N2 - Identifying hot spots and hot moments of nitrous oxide (N2O) emissions in the landscape is critical for monitoring and mitigating the emission of this potent greenhouse gas. We propose a novel use of the Lorenz curve and Gini coefficient (G) to improve the estimation of the mean as well as the spatial and temporal variation of N2O emissions from a bioenergy landscape. The analyses indicate that the G was better correlated (R2 = 0.72, P < 0.001) with daily N2O emissions than the coefficient of variation and skewness. A hot moment for N2O emissions occurred after a storm event, with a heterogeneous spatial distribution of N2O emissions (G = 0.65); in contrast, CO2 emissions remained spatially uniform throughout the same period (G = 0.36). Volumetric soil air content below 0.03 m3 m−3 occurred more frequently in the wetter footslope positions and created N2O hot spots, with a high temporal inequality during the growing season (G = 0.75). In contrast, well-drained shoulder positions were cold spots, with uniformly distributed and low N2O emissions (G = 0.44). The spatial N2O inequality mirrored the landscape wetness generated by rain events, while biogeochemical equality prevailed in the landscape. The Lorenz curve and G are tools to standardize the spatial and temporal variation of N2O emissions across diverse landscapes and management scenarios. These two inequality indicators, in association with spatial maps, can help delineate the critical spatial mosaics and temporal windows of N2O emissions and guide landscape-scale monitoring and mitigation strategies to reduce N2O emissions.
AB - Identifying hot spots and hot moments of nitrous oxide (N2O) emissions in the landscape is critical for monitoring and mitigating the emission of this potent greenhouse gas. We propose a novel use of the Lorenz curve and Gini coefficient (G) to improve the estimation of the mean as well as the spatial and temporal variation of N2O emissions from a bioenergy landscape. The analyses indicate that the G was better correlated (R2 = 0.72, P < 0.001) with daily N2O emissions than the coefficient of variation and skewness. A hot moment for N2O emissions occurred after a storm event, with a heterogeneous spatial distribution of N2O emissions (G = 0.65); in contrast, CO2 emissions remained spatially uniform throughout the same period (G = 0.36). Volumetric soil air content below 0.03 m3 m−3 occurred more frequently in the wetter footslope positions and created N2O hot spots, with a high temporal inequality during the growing season (G = 0.75). In contrast, well-drained shoulder positions were cold spots, with uniformly distributed and low N2O emissions (G = 0.44). The spatial N2O inequality mirrored the landscape wetness generated by rain events, while biogeochemical equality prevailed in the landscape. The Lorenz curve and G are tools to standardize the spatial and temporal variation of N2O emissions across diverse landscapes and management scenarios. These two inequality indicators, in association with spatial maps, can help delineate the critical spatial mosaics and temporal windows of N2O emissions and guide landscape-scale monitoring and mitigation strategies to reduce N2O emissions.
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U2 - 10.1002/2017JG004041
DO - 10.1002/2017JG004041
M3 - Article
AN - SCOPUS:85041044742
SN - 2169-8953
VL - 123
SP - 193
EP - 206
JO - Journal of Geophysical Research: Biogeosciences
JF - Journal of Geophysical Research: Biogeosciences
IS - 1
ER -