{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,18]],"date-time":"2026-10-18T18:33:37Z","timestamp":1792348417504,"version":"4.4.0"},"reference-count":61,"publisher":"National Academy of Sciences","issue":"29","license":[{"start":{"date-parts":[[2025,7,15]],"date-time":"2025-07-15T00:00:00Z","timestamp":1752537600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000270","name":"UKRI | Natural Environment Research Council","doi-asserted-by":"publisher","award":["NE\/T000449\/1"],"award-info":[{"award-number":["NE\/T000449\/1"]}],"id":[{"id":"10.13039\/501100000270","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000270","name":"UKRI | Natural Environment Research Council","doi-asserted-by":"publisher","award":["QUINTUS; NE\/S015833\/1"],"award-info":[{"award-number":["QUINTUS; NE\/S015833\/1"]}],"id":[{"id":"10.13039\/501100000270","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2025,7,22]]},"abstract":"<jats:p>\n                    Forests are potential carbon (C) sinks that partially offset anthropogenic carbon dioxide (CO\n                    <jats:sub>2<\/jats:sub>\n                    ) emissions via enhanced C assimilation and productivity. However, the question remains whether mature trees will express sufficient plasticity in nutrient acquisition strategies to support enhanced growth under elevated CO\n                    <jats:sub>2<\/jats:sub>\n                    (eCO\n                    <jats:sub>2<\/jats:sub>\n                    ). Trees may sustain growth by investing C belowground to enhance nutrient acquisition, e.g., by increasing root absorptive surfaces for greater soil available resource exploration (a \u201cdo-it-yourself\u201d strategy) or utilizing C exudation or mycorrhizal associations as priming mechanisms for nutrient acquisition (\u201coutsourcing\u201d). We show that 4 y of eCO\n                    <jats:sub>2<\/jats:sub>\n                    (+140 \u00b1 38 ppm; i.e., +35% above ambient) altered the relative belowground C investment strategies of mature oak (\n                    <jats:italic toggle=\"yes\">Quercus robur<\/jats:italic>\n                    L.) in a 180-y-old temperate forest. Fine-root branching frequency increased 73% under eCO\n                    <jats:sub>2<\/jats:sub>\n                    . Specific root C exudation was enhanced under eCO\n                    <jats:sub>2<\/jats:sub>\n                    (63%), particularly outside the peak growing season, and the exudate C to nitrogen (N) ratio was increased (28%). Ectomycorrhizal (ECM) biomass production increased during leaf fall (17%) while ECM turnover increased almost fourfold under eCO\n                    <jats:sub>2<\/jats:sub>\n                    . The exudate and root metabolome composition were considerably altered during the late growing season under eCO\n                    <jats:sub>2<\/jats:sub>\n                    . We find, therefore, that a broad suite of nutrient acquisition strategies are upregulated under eCO\n                    <jats:sub>2<\/jats:sub>\n                    , with dynamic shifting between different outsourcing and do-it-yourself elements at different times of the year. These belowground changes support the increase in net primary productivity observed in this forest, with implications for the role of mature temperate forests in the global carbon sink.\n                  <\/jats:p>","DOI":"10.1073\/pnas.2503595122","type":"journal-article","created":{"date-parts":[[2025,7,15]],"date-time":"2025-07-15T17:45:22Z","timestamp":1752601522000},"update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":18,"title":["Elevated CO\n                    <sub>2<\/sub>\n                    alters relative belowground carbon investment for nutrient acquisition in a mature temperate forest"],"prefix":"10.1073","volume":"122","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6335-1690","authenticated-orcid":false,"given":"Michaela K.","family":"Reay","sequence":"first","affiliation":[{"name":"School of Geography, Earth and Environmental Science, University of Birmingham","place":["Birmingham, United 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Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Victoria","family":"Pastor","sequence":"additional","affiliation":[{"name":"Department of Biology, Biochemistry, and Natural Sciences, School of Technology and Experimental Sciences, Universitat Jaume I","place":["Castell\u00f3 de la Plana, Spain"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Angeliki","family":"Kourmouli","sequence":"additional","affiliation":[{"name":"Birmingham Institute of Forest Research, University of Birmingham","place":["Birmingham, United Kingdom"]},{"name":"Lancaster Environment Centre, Lancaster University","place":["Lancaster, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Miles","family":"Marshall","sequence":"additional","affiliation":[{"name":"School of Environmental and Natural Sciences, Bangor University","place":["Bangor, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Robert T.","family":"Grzesik","sequence":"additional","affiliation":[{"name":"School of Geography, Earth and Environmental Science, University of Birmingham","place":["Birmingham, United Kingdom"]},{"name":"Birmingham Institute of Forest Research, University of Birmingham","place":["Birmingham, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Iwan","family":"Evans","sequence":"additional","affiliation":[{"name":"School of Geography, Earth and Environmental Science, University of Birmingham","place":["Birmingham, United Kingdom"]},{"name":"Birmingham Institute of Forest Research, University of Birmingham","place":["Birmingham, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manon","family":"Rumeau","sequence":"additional","affiliation":[{"name":"School of Geography, Earth and Environmental Science, University of Birmingham","place":["Birmingham, United Kingdom"]},{"name":"Birmingham Institute of Forest Research, University of Birmingham","place":["Birmingham, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kris","family":"Hart","sequence":"additional","affiliation":[{"name":"Birmingham Institute of Forest Research, University of Birmingham","place":["Birmingham, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiaojiao","family":"Ma","sequence":"additional","affiliation":[{"name":"School of Geography, Earth and Environmental Science, University of Birmingham","place":["Birmingham, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0238-9828","authenticated-orcid":false,"given":"Richard J.","family":"Norby","sequence":"additional","affiliation":[{"name":"School of Geography, Earth and Environmental Science, University of Birmingham","place":["Birmingham, United Kingdom"]},{"name":"Birmingham Institute of Forest Research, University of Birmingham","place":["Birmingham, United 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Robert","family":"MacKenzie","sequence":"additional","affiliation":[{"name":"School of Geography, Earth and Environmental Science, University of Birmingham","place":["Birmingham, United Kingdom"]},{"name":"Birmingham Institute of Forest Research, University of Birmingham","place":["Birmingham, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2532-2236","authenticated-orcid":false,"given":"R. 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