Plant–soil feedback in native vs. invasive populations of a range expanding plant

Abstract

Although plant–soil feedback has been suggested as a mechanism that drives the success of invasive plants, studies that investigate differences in the intensity of plant–soil feedback among native and invasive populations of the same species are still lacking. However, such knowledge is important because it can provide an understanding of the mechanisms responsible for the spread of a species. Rorippa austriaca is a potentially invasive species - a successful range expander in Europe. We compared the plant–soil feedback of R. austriaca in populations from its native and invasive range. We explored both intraspecific feedback as well as feedback on a co-occurring grass species. Our results revealed a strong negative feedback effect as a consequence of soil conditioning by R. austriaca from the native range. On the contrary, a negative feedback effect was not observed for invasive R. austriaca. Interestingly, R. austriaca from the invasive range had a higher biomass than native R. austriaca. Our results might be explained by pathogen accumulation and soil modification by native R. austriaca, which had strong intra- and interspecific effects that seemed to be lost in the invasive R. austriaca. The loss of negative intraspecific plant–soil feedback and the increased growth of the invasive population may contribute to its successful range expansion. In spite of its increased growth, the co-occurring grass species is expected to successfully coexist with the invasive R. austriaca.