Elevated CO2 increases tree‐level intrinsic water use efficiency: insights from carbon and oxygen isotope analyses in tree rings across three forest FACE sites. Issue 2 (5th December 2012)

• Record Type: Journal Article
• Authors: Battipaglia, Giovanna; Saurer, Matthias; Cherubini, Paolo; Calfapietra, Carlo; McCarthy, Heather R.; Norby, Richard J.; Francesca Cotrufo, M.
• Is Part Of: New phytologist. Volume 197:Issue 2(2013)
• Page Start: 544
• Page End: 554
• Publication Date: 2012-12-05
• Subjects: Botany -- Periodicals; 580
• DOI: 10.1111/nph.12044
• Languages: English
• ISSNs: 0028-646X

Abstract

<abstract abstract-type="main" id="nph12044-abs-0001"> <title>Summary</title> <p> <list id="nph12044-list-0001" list-type="bullet"> <list-item> <p>Elevated CO<sub>2</sub> increases intrinsic water use efficiency (WUE<sub><italic>i</italic></sub>) of forests, but the magnitude of this effect and its interaction with climate is still poorly understood.</p> </list-item> <list-item> <p>We combined tree ring analysis with isotope measurements at three Free Air CO<sub>2</sub> Enrichment (FACE, POP‐EUROFACE, in Italy; Duke FACE in North Carolina and ORNL in Tennessee, USA) sites, to cover the entire life of the trees. We used δ<sup>13</sup>C to assess carbon isotope discrimination and changes in water‐use efficiency, while direct CO<sub>2</sub> effects on stomatal conductance were explored using δ<sup>18</sup>O as a proxy.</p> </list-item> <list-item> <p>Across all the sites, elevated CO<sub>2</sub> increased <sup>13</sup>C‐derived water‐use efficiency on average by 73% for <italic>Liquidambar styraciflua</italic>, 77% for <italic>Pinus taeda</italic> and 75% for <italic>Populus sp</italic>., but through different ecophysiological mechanisms.</p> </list-item> <list-item> <p>Our findings provide a robust means of predicting water‐use efficiency responses from a variety of tree species exposed to variable environmental conditions over time, and species‐specific relationships that can help modelling elevated CO<sub>2</sub> and climate impacts on forest productivity, carbon and water balances.</p> </list-item> </list> </p> </abstract>