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Article: Redefining droughts for the U.S. Corn Belt: The dominant role of atmospheric vapor pressure deficit over soil moisture in regulating stomatal behavior of Maize and Soybean

TitleRedefining droughts for the U.S. Corn Belt: The dominant role of atmospheric vapor pressure deficit over soil moisture in regulating stomatal behavior of Maize and Soybean
Authors
KeywordsAgroecosystem
Agricultural drought
Ecosystem stomatal conductance
Vapor pressure deficit
Soil water content
Issue Date2020
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/agrformet
Citation
Agricultural and Forest Meteorology, 2020, v. 287, p. article no. 107930 How to Cite?
AbstractThe U.S. Corn Belt, the world's biggest production region for corn and soybean combined, is prone to droughts. Currently 92% of the U.S. Corn Belt croplands are rainfed, and thus are sensitive to interannual climate variability and future climate change. Most prior studies identify the lack of soil moisture as the primary cause of agricultural drought impacts, although water-related stresses are also induced by high atmospheric water demands (i.e., vapor pressure deficit, VPD). Here we empirically attributed the variability of canopy-level stomatal conductance (Gs) and gross primary productivity (GPP) to VPD and soil water supply (i.e. volumetric soil water content, SWC), using eddy-covariance data from seven AmeriFlux eddy covariance sites in maize and soybean fields across the U.S. Corn Belt, which are well represented for the current rainfed part of the Corn Belt croplands. We used three independent approaches, including two statistical models (i.e. a multiple-linear regression model and a semi-empirical, non-linear model) and information theory, to quantify the relationship of Gs (or GPP) with VPD and SWC. The attribution result from the two models shows that VPD explains most of Gs variability (91% and 89%, respectively), and mutual information also attributed 91% of GPP variability to VPD. This finding was robust over the gradients of rainfall and temperature, crop types (maize vs. soybean), and management practices (whether irrigated or not). We reconciled our finding with the previously emphasized importance of precipitation and SWC, by conducting a path analysis, which revealed the causal relationships between precipitation, air temperature (Ta), relative humidity (RH), VPD, SWC, and Gs. We find that precipitation impacts on Gs through reduced RH and Ta to VPD (rather than directly through SWC). With increased VPD robustly projected under climate change, we expect increased crop water stress in the future for the U.S. Corn Belt.
Persistent Identifierhttp://hdl.handle.net/10722/283328
ISSN
2019 Impact Factor: 4.651
2015 SCImago Journal Rankings: 2.180

 

DC FieldValueLanguage
dc.contributor.authorKimm, H-
dc.contributor.authorGuan, K-
dc.contributor.authorGentine, P-
dc.contributor.authorWu, J-
dc.contributor.authorBernacchi, CJ-
dc.contributor.authorSulman, BN-
dc.contributor.authorGriffis, TJ-
dc.contributor.authorLin, C-
dc.date.accessioned2020-06-22T02:55:05Z-
dc.date.available2020-06-22T02:55:05Z-
dc.date.issued2020-
dc.identifier.citationAgricultural and Forest Meteorology, 2020, v. 287, p. article no. 107930-
dc.identifier.issn0168-1923-
dc.identifier.urihttp://hdl.handle.net/10722/283328-
dc.description.abstractThe U.S. Corn Belt, the world's biggest production region for corn and soybean combined, is prone to droughts. Currently 92% of the U.S. Corn Belt croplands are rainfed, and thus are sensitive to interannual climate variability and future climate change. Most prior studies identify the lack of soil moisture as the primary cause of agricultural drought impacts, although water-related stresses are also induced by high atmospheric water demands (i.e., vapor pressure deficit, VPD). Here we empirically attributed the variability of canopy-level stomatal conductance (Gs) and gross primary productivity (GPP) to VPD and soil water supply (i.e. volumetric soil water content, SWC), using eddy-covariance data from seven AmeriFlux eddy covariance sites in maize and soybean fields across the U.S. Corn Belt, which are well represented for the current rainfed part of the Corn Belt croplands. We used three independent approaches, including two statistical models (i.e. a multiple-linear regression model and a semi-empirical, non-linear model) and information theory, to quantify the relationship of Gs (or GPP) with VPD and SWC. The attribution result from the two models shows that VPD explains most of Gs variability (91% and 89%, respectively), and mutual information also attributed 91% of GPP variability to VPD. This finding was robust over the gradients of rainfall and temperature, crop types (maize vs. soybean), and management practices (whether irrigated or not). We reconciled our finding with the previously emphasized importance of precipitation and SWC, by conducting a path analysis, which revealed the causal relationships between precipitation, air temperature (Ta), relative humidity (RH), VPD, SWC, and Gs. We find that precipitation impacts on Gs through reduced RH and Ta to VPD (rather than directly through SWC). With increased VPD robustly projected under climate change, we expect increased crop water stress in the future for the U.S. Corn Belt.-
dc.languageeng-
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/agrformet-
dc.relation.ispartofAgricultural and Forest Meteorology-
dc.subjectAgroecosystem-
dc.subjectAgricultural drought-
dc.subjectEcosystem stomatal conductance-
dc.subjectVapor pressure deficit-
dc.subjectSoil water content-
dc.titleRedefining droughts for the U.S. Corn Belt: The dominant role of atmospheric vapor pressure deficit over soil moisture in regulating stomatal behavior of Maize and Soybean-
dc.typeArticle-
dc.identifier.emailWu, J: jinwu@hku.hk-
dc.identifier.authorityWu, J=rp02509-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.agrformet.2020.107930-
dc.identifier.scopuseid_2-s2.0-85079836133-
dc.identifier.hkuros310542-
dc.identifier.volume287-
dc.identifier.spagearticle no. 107930-
dc.identifier.epagearticle no. 107930-
dc.publisher.placeNetherlands-

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