Effect of past agricultural use on the infectivity and composition of a community of arbuscular mycorrhizal fungi

When species-rich semi-natural grasslands undergo conversion to arable fields and back to grasslands, the effect of past intensive agricultural management may persist for decades in the form of decreased plant diversity. Arbuscular mycorrhizal fungi (AMF) are an important component of grassland ecosystems affecting the biodiversity and productivity of plant communities, but little is known about their long-term response to past agricultural management after the abandonment of fields. The aim of this study was to compare the infectivity and composition of the AMF communities of a former field, abandoned 25 years ago, and a neighboring non-disturbed grassland, and to assess whether the composition of intraradical AMF communities can be linked to the inability of some plant species to colonize the abandoned field. AMF infectivity and diversity were evaluated in soil and root samples of 12 plant species differing in their ability to colonize abandoned fields. The abandoned field hosted the same pool of AMF taxa as the undisturbed grassland but the community of AMF colonized plant roots faster from a lower number of infective propagules in the abandoned field than in the grassland. The composition of intraradical AMF communities was affected by the biotope and the plant species, but was unrelated to the ability of the plant species to colonize the abandoned field. It is therefore concluded that plants and AMF have colonized the abandoned field independently and that differences between the AMF communities of the two biotopes reflect persisting differences in soil characteristics.