Effects of arbuscular mycorrhizal colonisation on shoot and root decomposition of different plant species and species mixtures

We studied the decomposition of shoot and root tissues of four plant species from central Argentina belonging to contrasting functional types: a deciduous shrub (Acacia caven), a perennial forb (Hyptis mutabilis), an annual forb (Bidens pilosa) and a tussock grass (Jarava pseudoichu). They were grown from seed in a greenhouse in isolation or in 2- or 4-species mixtures, with and without arbuscular mycorrhizal fungi (AMF), and then placed to decompose under natural conditions in the field. AMF significantly enhanced decomposition of shoots, but not that of roots, independently of species identity and species-mixture composition. Our results suggest that AMF may be significantly affecting ecosystem functioning through the observed plant-mediated effects on decomposition.