Deep Soil Conditions Make Mediterranean Cork Oak Stem Growth Vulnerable to Autumnal Rainfall Decline in Tunisia

Forests

Florent Mouillot¹  Fatma Gharbi²  Frederic Guibal³  Salwa Rejeb⁴  Mohamed N. Rejeb⁴  Lobna Zribi⁴ 

[1] CEFE, UMR 5175, CNRS-Université de Montpellier-Université Paul Valéry Montpellier, EPHE-IRD, 1919 route de Mende, Montpellier 34293, France;Faculté des Sciences de Tunis, département de Biologie, Tunis 2092, Tunisie;IMBE, UMR 7263, CNRS-Aix Marseille Université-IRD, Avignon Université, Europôle de l’Arbois, BP 80, Aix en Provence 13545, France;Institut National de Recherche en Génie Rural, Eaux et Forêts, Rue Hedi Karray, Ariana 2080, Tunisie;

关键词: Quercus suber L.;    dendrochronology;    drought;    phenology;    water model;    climate change;   

DOI  :  10.3390/f7100245

来源: DOAJ

【 摘 要 】

Tree rings provide fruitful information on climate features driving annual forest growth through statistical correlations between annual tree growth and climate features. Indices built upon tree growth limitation by carbon sequestration (source hypothesis) or drought-driven cambial phenology (sink hypothesis) can be used to better identify underlying processes. We used both analytical frameworks on Quercus suber, a sparsely studied species due to tree ring methodological issues, and growing on a favorable sub-humid Mediterranean climate and deep soil conditions in Tunisia (North Africa). Statistical analysis revealed the major role of autumnal rainfall before the growing season on annual tree growth over the 1918–2008 time series. Using a water budget model, we were able to explain the critical role of the deep soil water refill during the wet season in affecting both the drought onset controlling growth phenology and the summer drought intensity affecting carbon assimilation. Analysis of recent climate changes in the region additionally illustrated an increase in temperatures enhancing the evaporative demand and advancing growth start, and a decline in rainfalls in autumn, two key variables driving stem growth. We concluded on the benefits of using process-based indices in dendrochronological analysis and identified the main vulnerability of this Mediterranean forest to autumnal rainfall decline, a peculiar aspect of climate change under summer-dry climates.

【 授权许可】

Unknown