The Functioning of Rhizosphere Biota in Wetlands – a Review

Anoxia and harmful metabolites are two of several particularities that characterize wetland soils and make their study so fascinating. Unique physiological and anatomical adaptations in roots of wetland plants allow them to exploit the light, water and nutrients available in the wetland. The adapted roots are surrounded by a rhizosphere, which attracts by its water, oxygen, nutrients and physical protection a myriad of wetland-specialized organisms. These organisms, which include viruses, bacteria and archaea (such as N-fixers, nitrifiers and methanotrophs), fungi (such as mycorrhizal fungi), protozoa and animals, determine the ecological functioning of the vegetated wetland through their interactions with the roots, with each other and with their inanimate environment. Several of these interactions, especially the globally significant immobilization of carbon and emission of greenhouse gases, are unique to wetlands. The present review highlights the main issues and gaps in our understanding of the contribution of rhizosphere biota to the ecological functioning of the widespread and globally important vegetated wetlands. Multi-disciplinary research teams that use modern technologies and approaches could help close these gaps.