Root and chemical traits

Many studies have quantified the functional variation of fine root traits to understand the overarching trade-off between maximizing resource acquisition or conservation (root economics spectrum -RES-). However, we know remarkably less on how plant strategies along the RES are actually constrained by the amount of photosynthates required to construct roots (i.e. construction costs, CC) or how belowground interactions with symbiotic organisms modify root trait patterns and their relationships with CC. Our main aim was to quantify CC of fine roots (<2 mm) and their underlying components (carbon, minerals and organic nitrogen concentrations) in 60 Mediterranean woody species with contrasting symbiotic association types (ectomycorrhizas, arbuscular and ericoid mycorrhizas and N-fixing bacteria). We examined (1) if the covariation among fine root traits along the RES was related to the intrinsic cost of producing roots and if this relationship was dependent on the type of root symbiosi...