Tree roots can penetrate deeply in African semi-deciduous rain forests: evidence from two common soil types
2015
Freycon, Vincent | Wonkam, Christelle | Fayolle, Adeline | Laclau, Jean-Paul | Lucot, Eric | Jourdan, Christophe | Cornu, Guillaume | Gourlet-Fleury, Sylvie | Biens et services des écosystèmes forestiers tropicaux (UPR BSef) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad) | Institut des Sciences de l'Evolution de Montpellier (UMR ISEM) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE) ; Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS) | Université de Yaoundé I (UY1) | Ministère des Eaux, Forêts, Chasse et Pêche [République Centrafricaine] | Gembloux Agro-Bio Tech [Faculté universitaire des sciences agronomiques de Gembloux] ([FUSAGx]) ; Université de Liège = University of Liège = Universiteit van Luik = Universität Lüttich (ULiège) | Unité de recherche sur la productivité des plantations industrielles ; Institut National Agronomique Paris-Grignon (INA P-G) | Ecologie Fonctionnelle et Biogéochimie des Sols (Eco&Sols) ; Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Ecole Nationale Supérieure Agronomique de Montpellier (ENSA M) | Laboratoire Chrono-environnement (UMR 6249) (LCE) ; Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC) ; Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC) | Département Forêt (Cirad-FORET) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad) | ERA-Net BiodivERsA; national funders ANR (France); NERC (UK) BiodivERsA call for research proposals; AFD | ANR-08-BDVA-0001,CoForChange,Comment, pourquoi et où les espèces d'arbres survivront-elles à une augmentation des perturbations : diagnostic et outils d'aide à la decision pour atténuer l'effet des changements globaux sur la biodiversité dans les forêts du bassin du Congo.(2008)
International audience
显示更多 [+] 显示较少 [-]英语. Despite the important functional role of deep roots in withdrawing water during drought, direct measurements of root distribution are very rare in tropical rain forests. The aim of this study was to investigate the root distribution of Entandrophragma cylindricum, a common tree species in the Central African semi-deciduous rain forest, in Ferralsols and Arenosols. We dug two pits to a depth of 6 m in Ferralsols and two pits to a depth of 3 m in Arenosols, close to E. cylindricum trees. The vertical soil profiles were divided into 10 x 10-cm grid cells and the roots counted were distributed in three diameter classes. We fitted a root distribution model to our dataset. We found that vertical root distribution was shallower in Arenosols than in Ferralsols. Root penetration was not stopped even by a Ferralsol with high gravel content in its subsoil. Overall, our measurements showed that 95% of all roots were distributed to depths of between 258 and 564 cm from the soil surface, which is much deeper than the 95 cm depth previously reported in the literature for tropical rain forests. As sampling depth could explain this discrepancy, we recommend a sampling depth of at least 3-5 m to accurately estimate root distribution. The drier the dry season, the deeper the sampling depth should be. Our results are consistent with global models of root distribution in forest ecosystems, which are driven by climate variables. We thus suggest that deep rooting could be common in rain forests with a marked dry season.
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