Biotic Novelty Index as a measure of the impact of invasive plant species on fungal communities in soil
S-K. SEPP, K. PÜSSA, K. KALJUND, P. GYAMFI, K. KOOREM
Institute of Ecology and Earth Sciences, University of Tartu, Ülikooli 18, 50090 Tartu, Estonia

Multiple mechanisms can enable species to spread outside their native range. According to Darwin’s Conundrum, successful novel species can be either closely related to native species, allowing them to take advantage of mutualistic organisms in their new range, or success derives from differences that enable escape from specialised pathogens. The Biotic Novelty Index (BNI) has recently been proposed to quantify the differences between native and invading plant species, considering the mismatch of plant traits and coexistence time. We use invasion gradients of two widespread aliens, Reynoutria japonica and Solidago canadensis , to test if BNI can be used to predict the shift these plant species cause in soil communities. We focus on the dynamics of different guilds of soil fungi, e.g. mycorrhizal and pathogenic fungi. We test the hypothesis that increasing BNI is related to decreasing fungal diversity across both invasive plant species. Comparing the species, S. canadensis , which has closely related plant species in the native flora and establishes communities with lower BNI, brings about a weaker shift than R. japonica . Altogether, these results will present a new approach for generalising the effect of invasive plant species on other trophic levels across plant species and habitats.