Shifting Dynamics: Decoupling of Carbon and Water Cycles in the Amazon Rainforest

Shifting Dynamics: Decoupling of Carbon and Water Cycles in the Amazon Rainforest | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Physical Sciences - Article Shifting Dynamics: Decoupling of Carbon and Water Cycles in the Amazon Rainforest Sarah Worden, Sassan Saatchi, Nate Mcdowell, Nima Madani, Yan Yang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6908939/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Tropical rainforest carbon and water cycles are typically assumed to be tightly coupled - defined here as exhibiting strong positive correlations - since plants exchange water for carbon through stomatal conductance1, 2. However, our analysis of 40 years of remote sensing-based estimates of gross primary production (GPP) and evapotranspiration (ET) across the Amazon Basin reveals that this coupling is both spatially and temporally non-stationary. We find that 64% of the Basin exhibits weakly positive (R<0.3) or negative (R<0) correlations between GPP and ET, particularly in regions with lowest water deficits (WD; R=0.08±0.23). These weakly positive or negative correlations are largely driven by declines in R during the dry season, implying that seasonal environmental, physiological, or phenological controls on GPP and ET diverge in areas with minimal water stress. Moreover, the strength of GPP-ET correlations has declined since 1982 coinciding with rising vapor pressure deficit (VPD) across the basin. This weakening is likely due to rising CO2 and VPD suppressing canopy conductance (Gc), thereby reducing GPP without limiting the VPD-driven increase in ET. If this decoupling trend continues, it could amplify drought impacts by increasing water loss relative to carbon gain, ultimately reducing the Amazon’s role as a carbon sink. Earth and environmental sciences/Climate sciences/Biogeochemistry/Carbon cycle Earth and environmental sciences/Climate sciences/Climate change/Climate-change impacts Full Text Additional Declarations There is NO Competing Interest. Supplementary Files AmazonGPPETSupportingInfoSubmitVersion.docx Supporting Information for Shifting Dynamics: Decoupling of Carbon and Water Cycles in the Amazon Rainforest Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6908939","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Physical Sciences - Article","associatedPublications":[],"authors":[{"id":485196287,"identity":"6d5a8d18-45dc-4783-836c-33c284263021","order_by":0,"name":"Sarah 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However, our analysis of 40 years of remote sensing-based estimates of gross primary production (GPP) and evapotranspiration (ET) across the Amazon Basin reveals that this coupling is both spatially and temporally non-stationary. We find that 64% of the Basin exhibits weakly positive (R\u003c0.3) or negative (R\u003c0) correlations between GPP and ET, particularly in regions with lowest water deficits (WD; R=0.08±0.23). These weakly positive or negative correlations are largely driven by declines in R during the dry season, implying that seasonal environmental, physiological, or phenological controls on GPP and ET diverge in areas with minimal water stress. Moreover, the strength of GPP-ET correlations has declined since 1982 coinciding with rising vapor pressure deficit (VPD) across the basin. This weakening is likely due to rising CO2 and VPD suppressing canopy conductance (Gc), thereby reducing GPP without limiting the VPD-driven increase in ET. 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