Shifting carbon sink patterns driven by reduced sunlight and increased contribution from shaded leaves

Shifting carbon sink patterns driven by reduced sunlight and increased contribution from shaded leaves | 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 Research Article Shifting carbon sink patterns driven by reduced sunlight and increased contribution from shaded leaves Jinjun Du, Luhua Wu, Heng Wei, Dan Chen, Dongni Yang, Lusha Xiong, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7051659/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 Jan, 2026 Read the published version in Carbon Balance and Management → Version 1 posted 13 You are reading this latest preprint version Abstract Global warming has led to pronounced differences in photosynthesis and respiration between sunlit and shaded leaves. However, assessments of the resulting disparities in carbon sequestration potential and contributions remain limited, and the underlying mechanisms have yet to be systematically elucidated. This study used three carbon flux indicators—gross primary productivity (GPP), sunlit leaf GPP (GPPsun), and shaded leaf GPP (GPPshade)—to reveal the spatiotemporal dynamics and driving mechanisms of carbon sinks in the terrestrial ecosystems of southern China. The Lindeman-Merenda-Gold model was applied to quantify the relative contributions of climate change to carbon sink variations. The results showed the following: (1) GPP, GPPsun, and GPPshade exhibited increasing but fluctuating trends during the period 2001–2020, with growth rates reaching 10.88, 5.69, and 5.19 g C m −2 yr −1 , respectively. In 44.79% of the study area, GPPshade increased faster than GPPsun. (2) GPPshade/GPP showed an increasing trend (0.03%), with a mean value of 0.54. The contribution of shaded leaves to the carbon sink was 1.79 times higher than that of sunlit leaves. (3) Declining solar radiation (SR) dominated this shift. The contribution rates of SR to GPP, GPPsun, and GPPshade were 28.01%, 24.55%, and 34.52%, respectively. SR was the primary driver in 37.46%, 31.02%, and 50.19% of the entire study area. (4) In areas with decreased SR, GPPsun exhibited slow growth, and GPPshade decreased. In areas with increased SR, GPPshade surged, while GPPsun growth decelerated significantly. Shaded leaf carbon sinks emerged as the dominant contributor to the overall enhancement of vegetation carbon sinks. These findings demonstrate a key mechanism—increased GPPshade potential driven by SR decline, suppression of GPPsun, and a resulting restructuring of carbon sink dynamics. This study provides theoretical support for enhancing terrestrial ecosystem carbon sinks and offers valuable insights for advancing global carbon neutrality objectives. Karst GPP Vegetation Carbon sink Climate change Ecological restoration Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 28 Jan, 2026 Read the published version in Carbon Balance and Management → Version 1 posted Editorial decision: Revision requested 08 Aug, 2025 Reviews received at journal 27 Jul, 2025 Reviews received at journal 26 Jul, 2025 Reviews received at journal 26 Jul, 2025 Reviewers agreed at journal 23 Jul, 2025 Reviewers agreed at journal 23 Jul, 2025 Reviewers agreed at journal 23 Jul, 2025 Reviews received at journal 23 Jul, 2025 Reviewers agreed at journal 13 Jul, 2025 Reviewers invited by journal 13 Jul, 2025 Editor assigned by journal 12 Jul, 2025 Submission checks completed at journal 12 Jul, 2025 First submitted to journal 05 Jul, 2025 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. 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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-7051659","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":484836100,"identity":"57fb7635-7e8c-4566-83f4-576853685214","order_by":0,"name":"Jinjun Du","email":"","orcid":"","institution":"Tongren University","correspondingAuthor":false,"prefix":"","firstName":"Jinjun","middleName":"","lastName":"Du","suffix":""},{"id":484836101,"identity":"f4171eb9-709f-4f2e-a9fc-09590b5c41c8","order_by":1,"name":"Luhua 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However, assessments of the resulting disparities in carbon sequestration potential and contributions remain limited, and the underlying mechanisms have yet to be systematically elucidated. This study used three carbon flux indicators—gross primary productivity (GPP), sunlit leaf GPP (GPPsun), and shaded leaf GPP (GPPshade)—to reveal the spatiotemporal dynamics and driving mechanisms of carbon sinks in the terrestrial ecosystems of southern China. The Lindeman-Merenda-Gold model was applied to quantify the relative contributions of climate change to carbon sink variations. The results showed the following: (1) GPP, GPPsun, and GPPshade exhibited increasing but fluctuating trends during the period 2001–2020, with growth rates reaching 10.88, 5.69, and 5.19 g C m\u003csup\u003e−2\u003c/sup\u003e yr\u003csup\u003e−1\u003c/sup\u003e, respectively. In 44.79% of the study area, GPPshade increased faster than GPPsun. 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