Mycorrhiza influences plant community structure in succession on spoil banks

The experiment simulated a plant succession stage when perennial grasses (e.g. Calamagrostis epigejos) invade communities of annuals with different mycotrophy (e.g. Atriplex sagittata and Tripleurospermum inodorum) on coalmine spoil banks. Communities of these three model species were planted in 30 l microcosms either in the presence of pre-established mycelium network of three arbuscular mycorrhizal fungi (AMF) species (individually and in a mixture) or without AMF. Different AMF species had significantly different effects on individual plant species’ growth, which resulted in changes in plant community structure. While in the no-AMF treatment the non-mycotrophic plant species A. sagittata contributed nearly 70% to the total plant biomass, in the presence of the 3 AMF mixture the contribution of this species was only about 10%. Different effects of AMF on tiller formation by C. epigejos suggest that some AMF could have greater potential to promote the replacement of annuals by perennial grasses than others. It can be concluded that not merely the presence but also the identity of AMF present on spoil banks can affect the coexistence of plant dominants, the community structure and the progress of plant succession.