Attributing forest responses to global‐change drivers: limited evidence of a CO2‐fertilization effect in Iberian pine growth. (1st September 2015)

• Record Type: Journal Article
• Authors: Camarero, J. Julio; Gazol, Antonio; Tardif, Jacques C.; Conciatori, France
• Is Part Of: Journal of biogeography. Volume 42:Number 11(2015:Nov.)
• Page Start: 2220
• Page End: 2233
• Publication Date: 2015-09-01
• Subjects: Biogeography -- Periodicals; 578.09
• DOI: 10.1111/jbi.12590
• Languages: English
• ISSNs: 0305-0270

Abstract

<abstract abstract-type="main" id="jbi12590-abs-0001"> <title>Abstract</title> <sec id="jbi12590-sec-0001" sec-type="section"> <title>Aim</title> <p>Forest responses to global‐change drivers such as rising atmospheric CO<sub>2</sub> concentrations (<italic>C</italic><sub>a</sub>), warming temperatures and increased aridification will depend on tree species and site characteristics. We aim to determine if rising <italic>C</italic><sub>a</sub> enhances growth of coexisting pine species along broad ecological gradients in a drought‐prone area.</p> </sec> <sec id="jbi12590-sec-0002" sec-type="section"> <title>Location</title> <p>Iberian Range, Spain.</p> </sec> <sec id="jbi12590-sec-0003" sec-type="section"> <title>Methods</title> <p>We sampled 557 trees of five pine species encompassing a wide climatic gradient and measured their radial growth. We used nonlinear flexible statistics (generalized additive mixed models) to characterize growth trends and relate them to <italic>C</italic><sub>a</sub>, temperature and water balance.</p> </sec> <sec id="jbi12590-sec-0004" sec-type="section"> <title>Results</title> <p>The sites most responsive to the growing‐season water balance were dominated by <italic>Pinus pinaster</italic> and <italic>Pinus nigra</italic> at low elevations, whereas those most responsive to temperatures were high‐elevation <italic>Pinus sylvestris</italic> and <italic>Pinus uncinata</italic> stands. From 1950 onwards, most sites and species showed decreasing radial growth trends. Growth trends were coherent with a CO<sub>2</sub>‐related fertilization effect only in one <italic>P. sylvestris</italic> site.</p> </sec> <sec id="jbi12590-sec-0005" sec-type="section"> <title>Main conclusions</title> <p>We found little evidence of growth stimulation of Iberian pine forests due to rising <italic>C</italic><sub>a</sub>. The results indicated that any positive effect of a <italic>C</italic><sub>a</sub>‐induced growth increase was unlikely to reverse or cancel out the drought‐driven trends of reduced growth in most Mediterranean pine forests. Further assessments of CO<sub>2</sub>‐fertilization effects on forest growth should be carried out in sites where climatic stressors such as drought do not override the effects of rising <italic>C</italic><sub>a</sub> on forest growth.</p> </sec> </abstract>