Costa Rican coffee (Coffea arabica) plants are often grown in agroforests. Studying the relationship between shade-inducing trees on coffee plant biomass and root competition in the topsoil, and overall belowground net primary productivity (bNPP), Defrenet et al. estimate root biomass and bNPP at the stand level, taking into account deep roots and the positioning of coffee plants in relation to trees.
Coffee root systems are shown to comprise 49% of the total plant biomass; such a high ratio is possibly a consequence of shoot pruning. There was no significant impact of shade-inducing trees on the fine root biomass (2.3 t ha-1), suggesting that coffee root systems are very competitive in the topsoil.
This paper is part of the Root Biology Special Issue.