Climate variability in the last 12,500 years has shaped vegetation dynamics differently across West African savannas and forests

Climate variability in the last 12,500 years has shaped vegetation dynamics differently across West African savannas and forests | 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 Climate variability in the last 12,500 years has shaped vegetation dynamics differently across West African savannas and forests Sanusi Camara, Hamada E. Ali, Josep Peñuelas, Moisés Méndez-Toribio This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9570403/v2 This work is licensed under a CC BY 4.0 License Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Abstract This study examines how climate variability from the Younger Dryas to the present shapes vegetation dynamics across West African savannas and forests using pollen-based compositional and functional analyses. Fossil pollen assemblages were grouped into major ecological domains and harmonised with TRY trait records, retaining defensible matches for key numeric traits, such as specific leaf area, leaf area, wood density, and seed mass. Functional dispersion (FDis), the squared chord distance (SCD), and principal coordinate analysis (PCoA) were used to evaluate regional differences and long-term ecological change. Within the savanna domain, Sahelian and Sudanian assemblages were compositionally distinct but only modestly functionally differentiated, indicating broad overlap in the occupied trait space. Temporal structuring also differed between the two regions: in the Sahel, FDis increased significantly toward the present, whereas no equivalent monotonic trend was detected in Sudan. At the broader biome scale, compared with savanna assemblages, forest assemblages showed substantially greater FDis and compositional turnover. Complementary PCA and NMDS of the harmonised pollen matrix revealed the same broad forest–Savanna split, whereas PERMANOVA confirmed significant biome-scale compositional differentiation (R² = 0.1309, p = 0.001) and highlighted additional regional structuring across the dataset. Trait trajectories further suggested more conservative strategies in savanna communities, with higher wood density and lower specific leaf area, whereas forest assemblages were more variable and structurally complex. The independent proxy variables showed limited direct explanatory power for FDis, with age, South Atlantic SST, δ¹³C, and δ¹⁸O emerging as the dominant predictors for Sahel. Overall, the results demonstrate that Holocene vegetation change in West Africa was biome-specific, regionally uneven, and characterised by stronger compositional differentiation than functional differentiation within the savanna domain. Paleoecology Terrestrial Ecology Forestry Holocene West Africa Vegetation dynamics Climate variability Fossil pollen Plant functional traits Functional diversity Proxy analysis Full Text Additional Declarations The authors declare no competing interests. Supplementary Files suplementarymaterials.docx Cite Share Download PDF Status: Posted Version 2 posted You are reading this latest preprint version Show more versions 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-9570403","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":633831639,"identity":"ce672365-859c-467b-93fc-df423af2ab55","order_by":0,"name":"Sanusi Camara","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0klEQVRIiWNgGAWjYDADfgjFTIIWyQZmUrUYHCBWi3wD88NPN2ruyRvfyD/8gqHCOrGBf3UCAcPZjKVzjhUbbruRzGbBcCY9sUHi7Qb8Whh4GKRz2BIYQVoMGNsOA7Wcxa9FvoGH+XfOvwT7zTNAWv4RoYXhAA+bdG5bQuIGiWTmB4wNQC38vQQcdpjNzDq3LyF5xpnHZgwJx9KN2yR4CTisvfnx7ZxvCbb97YmPP3yosZbt5yfkMKSIYJNIgJNEAuYPYIr/APFaRsEoGAWjYEQAAAXuReKCUjVBAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0009-0006-7722-6827","institution":"University of The Gambia, Department of Geography, Division of Humanities and Social Sciences, Faraba campus, The Gambia","correspondingAuthor":true,"prefix":"","firstName":"Sanusi","middleName":"","lastName":"Camara","suffix":""},{"id":633831640,"identity":"1d72d77f-7edd-4bd3-b0c6-28e4b452e87c","order_by":1,"name":"Hamada E. 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Fossil pollen assemblages were grouped into major ecological domains and harmonised with TRY trait records, retaining defensible matches for key numeric traits, such as specific leaf area, leaf area, wood density, and seed mass. Functional dispersion (FDis), the squared chord distance (SCD), and principal coordinate analysis (PCoA) were used to evaluate regional differences and long-term ecological change. Within the savanna domain, Sahelian and Sudanian assemblages were compositionally distinct but only modestly functionally differentiated, indicating broad overlap in the occupied trait space. Temporal structuring also differed between the two regions: in the Sahel, FDis increased significantly toward the present, whereas no equivalent monotonic trend was detected in Sudan. At the broader biome scale, compared with savanna assemblages, forest assemblages showed substantially greater FDis and compositional turnover. Complementary PCA and NMDS of the harmonised pollen matrix revealed the same broad forest\u0026ndash;Savanna split, whereas PERMANOVA confirmed significant biome-scale compositional differentiation (R\u0026sup2; = 0.1309, p\u0026thinsp;=\u0026thinsp;0.001) and highlighted additional regional structuring across the dataset. Trait trajectories further suggested more conservative strategies in savanna communities, with higher wood density and lower specific leaf area, whereas forest assemblages were more variable and structurally complex. The independent proxy variables showed limited direct explanatory power for FDis, with age, South Atlantic SST, δ\u0026sup1;\u0026sup3;C, and δ\u0026sup1;⁸O emerging as the dominant predictors for Sahel. Overall, the results demonstrate that Holocene vegetation change in West Africa was biome-specific, regionally uneven, and characterised by stronger compositional differentiation than functional differentiation within the savanna domain.\u003c/p\u003e","manuscriptTitle":"Climate variability in the last 12,500 years has shaped vegetation dynamics differently across West African savannas and forests","msid":"","msnumber":"","nonDraftVersions":[{"code":2,"date":"2026-05-15 19:52:06","doi":"10.21203/rs.3.rs-9570403/v2","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}},{"code":1,"date":"2026-05-04 04:48:10","doi":"10.21203/rs.3.rs-9570403/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b9dc5cc1-d9cf-435a-9c95-763cdf48a221","owner":[],"postedDate":"May 15th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":67453323,"name":"Paleoecology"},{"id":67453324,"name":"Terrestrial Ecology"},{"id":67453325,"name":"Forestry"}],"tags":[],"updatedAt":"2026-05-04T04:48:11+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-15 19:52:06","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v2","identity":"rs-9570403","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9570403","identity":"rs-9570403","version":["v2"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}