“…The biomass of trees comprises the majority of biomass in tropical forests and trees (Saatchia et al, 2011), but nevertheless the role of below-ground biomass pools and interactions require further examination as resource competition is a net measure of above-and below-ground plant-plant interactions. Roots account for a substantial proportion of tree biomass (almost 30 percent of the total biomass of young trees in a nearby plantation; Sinacore et al, 2017) and root:shoot ratios and root architecture are likely to shift along successional and other environmental gradients (Jaramillo, Ahedo-Hernández, & Kauffman, 2003;Rasmann, Bauerle, Poveda, & Vannette, 2011;van Noordwijk, Cadisch, & Ong, 2004;Zangaro, Alves, Lescano, Ansanelo, & Nogueira, 2012) and to differ across tree species and functional groups (Becker & Castillo, 1990;Markesteijn & Poorter, 2009;Shukla & Ramakrishnan, 1984;Sinacore et al, 2017). Including roots in future studies is a major challenge but will refine our ability to understand the role of N 2 fixer species in secondary forest succession.…”