Simulating precipitation decline under a Mediterranean deciduous Oak forest: effects on isoprene seasonal emissions and predictions under climatic scenarios
| Autor: | Elena Ormeño, Brice Temine-Roussel, Catherine Fernandez, Svenja Bartsch, J. Lathière, Jean-Philippe Orts, Christophe Boissard, Ilja M. Reiter, Henri Wortham, Bertrand Guenet, Thierry Gauquelin, Anne-Cyrielle Genard-Zielinski |
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| Rok vydání: | 2017 |
| Předmět: |
Mediterranean climate
Stomatal conductance 010504 meteorology & atmospheric sciences Water stress Edaphic 010501 environmental sciences 01 natural sciences chemistry.chemical_compound Animal science chemistry Climatology Soil water Environmental science Oak forest Isoprene 0105 earth and related environmental sciences |
| DOI: | 10.5194/bg-2017-17 |
| Popis: | Seasonal variations of Q. pubescens physiology and isoprene emission rates (ER) were studied from June 2012 to June 2013 at the O3HP site (French Mediterranean) under natural (ND) and amplified (+30 %, AD) drought. While AD significantly reduced the stomatal conductance to water vapour over the season excepting August, it did not significantly limit CO2 net assimilation, which was the lowest in summer. ER followed a significant seasonal pattern, whatever the drought intensity, with mean ER maxima of 78.5 and 104.8 µgC gDM−1 h−1 in July (ND) and August (AD) respectively. Isoprene emission factor increased significantly by a factor of 2 in August and September under AD (137.8 and 74.3 µgC gDM−1 h−1) compared to ND (75.3 and 40.21 µgC gDM−1 h−1), but no changes occurred on ER. An isoprene algorithm (G14) was developed using an optimised artificial neural network trained on our experimental dataset (ER + O3HP climatic and edaphic parameters cumulated over 0 to 21 days before measurements). G14 assessed more than 80 % of the observed ER seasonal variations, whatever the drought intensity. In contrast, ER was poorly assessed under water stress by MEGAN empirical isoprene model, in particular under AD. Soil water (SW) content was the dominant parameter to account for the observed ER variations, regardless the water stress treatment. ER was more sensitive to higher frequency environmental changes under AD (0 to −7 days) compared to ND (7 days). Using IPCC RCP2.6 and RCP8.5 climate scenarios, SW and temperature calculated by the ORCHIDEE land surface model, and G14, an annual 3 fold ER relative increase was found between present (2000–2010) and future (2090–2100) for RCP8.5 scenario compared to a 70 % increase for RCP2.6. Future ER remained mainly sensitive to SW (both scenarios) and became dependent to higher frequency environmental changes under RCP8.5. |
| Databáze: | OpenAIRE |
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