CO2 fertilization plays a minor role in long-term carbon accumulation patterns in temperate pine forests in the southwestern Pyrenees
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2021-07-04
Date
2019Author
Version
Acceso embargado / Sarbidea bahitua dago
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Artículo / Artikulua
Version
Versión aceptada / Onetsi den bertsioa
Project Identifier
ES/6PN/AGL2012‐33465 ES/1PE/AGL2016-76463-P
Impact
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10.1016/j.ecolmodel.2019.108737
Abstract
Isolating the long-term fertilization effect of CO 2 from other climate- and site-related effects on tree
growth has been proven a challenging task. To isolate long-term effects of [CO2] on water use
efficiency at ecosystem level, we used the FORECAST Climate forest model, calibrated for Scots pine (Pinus sylvestris L.) forests in the southwestern Pyrenees, growing at a Mediterranean montane ...
[++]
Isolating the long-term fertilization effect of CO 2 from other climate- and site-related effects on tree
growth has been proven a challenging task. To isolate long-term effects of [CO2] on water use
efficiency at ecosystem level, we used the FORECAST Climate forest model, calibrated for Scots pine (Pinus sylvestris L.) forests in the southwestern Pyrenees, growing at a Mediterranean montane site and at a continental subalpine site. Future climate scenarios (RCP 4.5 and RCP 8.5) were generated using a battery of six climate models to estimate daily values of temperature and
precipitation in a 90-year series. A factorial experiment was designed to disentangle the importance on C pools of three growing limiting factors (nitrogen limitation, climate (temperature +
precipitation) limitation and atmospheric CO 2 concentration). The relative importance of each factor was quantified by comparing the scenario with the limitation of each individual factor turned on
with the non-limitation scenario. Positive CO 2 fertilization due to improvement in water use
efficiency was detected by the model, but its quantitative impact improving tree growth was
minimum: its average increase in ecosystem C pools ranged from 0.3 to 0.9%. At the site with
cooler climate conditions (continental), the main limitation for tree growth was climate. Such
limitation will be reduced under climate change and the ecosystem will store more carbon. At the
site with milder climate conditions (Mediterranean), N availability was the main limiting factor
albeit modulated by water availability. Such limitation could be reduced under climate change as N cycling could accelerate (higher litterfall production and decomposition rates) but also increase if droughts become more frequent and severe. In addition, the magnitude of the uncertainty related to
climate model selection was much more important than CO 2 fertilization, indicating that
atmospheric processes are more important than tree physiological processes when defining how
much carbon could be gained (or lost) in forests under climate change. In conclusion, due to the
small changes in forest C pools caused by variation of atmospheric CO 2 concentrations compared to
changes caused by other growth limiting factors (nutrients, climate), reducing uncertainty related to
climate projections seems a more efficient way to reduce uncertainty in tree growth projections than
increasing forest model complexity. [--]
Subject
Publisher
Elsevier
Published in
Ecological Modelling 407 (2019) 108737
Departament
Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. IMAB - Institute for Multidisciplinary Research in Applied Biology
Publisher version
Sponsorship
Funding for this research has been provided by the Spanish Ministry of Economy and Competitiveness (projects AGL2012‐33465, AGL2016-76463-P), a Ramón y Cajal contract (ref.RYC‐2011‐08082) and Marie Curie Actions (ref CIG‐2012‐326718‐ECOPYREN3,H2020-MSCA-IF-2014-DENDRONUTRIENT).