Stoichiometric plasticity of microbial communities is similar between litter and soil in a tropical rainforest

Nicolas Fanin (1) , Nathalie Fromin (2) , Sandra Barantal (3) , Stephan Hättenschwiler (2)

1 FARE - Fractionnement des AgroRessources et Environnement
2 CEFE - Centre d’Ecologie Fonctionnelle et Evolutive
3 ECOFOG - Ecologie des forêts de Guyane

Heterotrophic microorganisms are commonly thought to be stoichiometrically homeostatic but their stoichiometric plasticity has rarely been examined, particularly in terrestrial ecosystems. Using a fertilization experiment in a tropical rainforest, we evaluated how variable substrate stoichiometry may influence the stoichiometry of microbial communities in the leaf litter layer and in the underlying soil. C:N:P ratios of the microbial biomass were higher in the organic litter layer than in the underlying mineral soil. Regardless of higher ratios for litter microbial communities, C, N, and P fertilization effects on microbial stoichiometry were strong in both litter and soil, without any fundamental difference in plasticity between these two communities. Overall, N:P ratios were more constrained than C:nutrient ratios for both litter and soil microbial communities, suggesting that stoichiometric plasticity arises because of a decoupling between C and nutrients. Contrary to the simplifying premise of strict homeostasis in microbial decomposers, we conclude that both litter and soil communities can adapt their C:N:P stoichiometry in response to the stoichiometric imbalance of available resources.

Domaines: Biodiversité et Ecologie; Milieux et Changements globaux; Interactions entre organismes; Ecosystèmes

Nicolas Fanin, Nathalie Fromin, Sandra Barantal, Stephan Hättenschwiler. Stoichiometric plasticity of microbial communities is similar between litter and soil in a tropical rainforest. Scientific Reports, 2017, 7 (1), pp.1-7. ⟨10.1038/s41598-017-12609-8⟩. ⟨hal-02127308⟩