[en] 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 × 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.
Research center :
Centre de Coopération International en Recherche Agronomique pour le Développement - CIRAD Institut Centrafricain de Recherche Agronomique - ICRA University of Bangui
Freycon, Vincent; CIRAD, UPR BSEF - Montpellier - France
Wonkam, Christelle; CIRAD, UPR BSEF - Montpellier - France
Fayolle, Adeline ; Université de Liège > Ingénierie des biosystèmes (Biose) > Gestion des ressources forestières et des milieux naturels
Laclau, Jean-Paul; CIRAD, UMR Eco&Sols - Montpellier - France
Lucot, Eric; UMR 6249 Chrono-Environnement - Besançon - France
Jourdan, Christophe; CIRAD, UMR Eco&Sols - Montpellier - France
Cornu, Guillaume; CIRAD, UPR BSEF - Montpellier - France
Gourlet-Fleury, Sylvie; CIRAD, UPR BSEF - Montpellier - France
Language :
English
Title :
Tree roots can penetrate deeply in African semi-deciduous rain forests: evidence from two common soil types
Publication date :
2015
Journal title :
Journal of Tropical Ecology
ISSN :
0266-4674
eISSN :
1469-7831
Publisher :
Cambridge University Press, New York, United States - New York
Volume :
31
Issue :
1
Pages :
13-23
Peer reviewed :
Peer Reviewed verified by ORBi
Name of the research project :
CoForChange Project (www.coforchange.eu)
Funders :
ERA-Net BiodivERsA AFD - Agence Française de Développement [FR]
Commentary :
This research is part of the CoForChange project (www.coforchange.eu). It was funded by the ERA-Net BiodivERsA, with the national funders ANR (France) and NERC (UK), part of the 2008 BiodivERsA call for research proposals. We thank the ARF Project (Appui à la Recherche Forestière) and its seven partners: AFD (Agence Française de Développement), CIRAD (Centre de Coopération Internationale en Recherche Agronomique pour le Développement), ICRA (Institut Centrafricain de Recherche Agronomique), MEFCP (Ministère centrafricain des Eaux, Forêts, Chasse and Pêche), SCAC/MAE(Service de Coopération and d’Actions Culturelles), University of Bangui and SCAD (Société Centrafricaine de Déroulage) for providing access to the M’Baïki. We thank IFB Industrie Forestière de Batalimo) for providing access to the Ngotto site. ChristelleWonkam was funded by AFD. We thank the two teams in the field who dug the pits at Mbaiki and Ngotto. We thank S. Guitet, J. Schenk and another anonymous reviewer for their insightful comments on a former version of the manuscript.
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