Root biomass, turnover and net primary productivity of a coffee agroforestry system in Costa Rica: effects of soil depth, shade trees, distance to row and coffee age

Defrenet Elsa, Roupsard Olivier, Van den Meersche Karel, Charbonnier Fabien, Pérez-Molina Junior Pastor, Khac Emmanuelle, Prieto Iván, Stokes Alexia, Roumet Catherine, Rapidel Bruno, de Melo Virginio Filho Elias, Vargas Victor J., Robelo Diego, Barquero Alejandra, Jourdan Christophe. 2016. Root biomass, turnover and net primary productivity of a coffee agroforestry system in Costa Rica: effects of soil depth, shade trees, distance to row and coffee age. Annals of Botany, 118 (4) : 833-851.

Quartile : Q1, Sujet : PLANT SCIENCES

Résumé : Background and Aims In Costa Rica, coffee (Coffea arabica) plants are often grown in agroforests. However, it is not known if shade-inducing trees reduce coffee plant biomass through root competition, and hence alter overall net primary productivity (NPP). We estimated biomass and NPP at the stand level, taking into account deep roots and the position of plants with regard to trees. Methods Stem growth and root biomass, turnover and decomposition were measured in mixed coffee/tree (Erythrina poeppigiana) plantations. Growth ring width and number at the stem base were estimated along with stem basal area on a range of plant sizes. Root biomass and fine root density were measured in trenches to a depth of 4 m. To take into account the below-ground heterogeneity of the agroforestry system, fine root turnover was measured by sequential soil coring (to a depth of 30 cm) over 1 year and at different locations (in full sun or under trees and in rows/inter-rows). Allometric relationships were used to calculate NPP of perennial components, which was then scaled up to the stand level. Key Results Annual ring width at the stem base increased up to 2·5 mm yr−1 with plant age (over a 44-year period). Nearly all (92 %) coffee root biomass was located in the top 1·5 m, and only 8 % from 1·5 m to a depth of 4 m. Perennial woody root biomass was 16 t ha−1 and NPP of perennial roots was 1·3 t ha−1 yr−1. Fine root biomass (0–30 cm) was two-fold higher in the row compared with between rows. Fine root biomass was 2·29 t ha−1 (12 % of total root biomass) and NPP of fine roots was 2·96 t ha−1 yr−1 (69 % of total root NPP). Fine root turnover was 1·3 yr−1 and lifespan was 0·8 years. Conclusions Coffee root systems comprised 49 % of the total plant biomass; such a high ratio is possibly a consequence of shoot pruning. There was no significant effect of trees on coffee fine root biomass, suggesting that coffee root systems are very competitive in the topsoil.

Mots-clés Agrovoc : Coffea arabica, agroforesterie, Erythrina poeppigiana, arbre d'ombrage, compétition végétale, espacement, racine, biomasse, croissance, profondeur de plantation, système racinaire

Mots-clés géographiques Agrovoc : Costa Rica

Classification Agris : F08 - Systèmes et modes de culture
K10 - Production forestière
F62 - Physiologie végétale - Croissance et développement

Champ stratégique Cirad : Axe 1 (2014-2018) - Agriculture écologiquement intensive

Auteurs et affiliations

• Defrenet Elsa, CATIE (CRI)
• Roupsard Olivier, CIRAD-PERSYST-UMR Eco&Sols (CRI)
• Van den Meersche Karel, CIRAD-PERSYST-UMR Eco&Sols (CRI) ORCID: 0000-0002-0866-7657
• Charbonnier Fabien, CATIE (CRI)
• Pérez-Molina Junior Pastor, CATIE (CRI)
• Khac Emmanuelle
• Prieto Iván, CNRS (FRA)
• Stokes Alexia, INRA (FRA)
• Roumet Catherine, CNRS (FRA)
• Rapidel Bruno, CIRAD-PERSYST-UMR SYSTEM (CRI) ORCID: 0000-0003-0288-5650
• de Melo Virginio Filho Elias, CATIE (CRI)
• Vargas Victor J., ICAFE (CRI)
• Robelo Diego, CNRS (FRA)
• Barquero Alejandra, Cafetalera Aquiares (CRI)
• Jourdan Christophe, CIRAD-PERSYST-UMR Eco&Sols (FRA) ORCID: 0000-0001-9857-3269

Source : Cirad-Agritrop (https://agritrop.cirad.fr/581451/)

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