Influence of arbuscular mycorrhizal fungi on root foraging and competitive ability depends on soil phosphorus distribution: evidence from two pairs of invasive and native plants

Abstract

Besides uptake of nutrients by roots, plants can acquire nutrients through arbuscular mycorrhizal fungi (AMF). AMF play a crucial role in plant growth and competition. However, few studies have investigated the effects of AMF on root foraging and competition between invasive and native species in response to heterogeneous nutrients. Two pairs of invasive and native plants of the Asteraceae family were selected to create a common garden experiment involving three factors (heterogeneous vs. homogeneous phosphorus (P), with vs. without AMF, and monoculture vs. mixture). The results showed that AMF significantly reduced the foraging scale of the invasive species, Bidens pilosa, and decreased the precision of the invasive species, Praxelis clematidea, and the native species, Emilia sonchifolia. In monoculture, AMF significantly decreased the total biomass of the two invasive species under heterogeneous P rather than homogeneous P, which was confirmed by N and P uptake. In mixture, heterogeneity significantly decreased the tolerance competitive ability of B. pilosa but increased that of P. clematidea. In the homogeneous P, AMF significantly decreased the suppression ability of B. pilosa, while in the heterogeneous P, AMF decreased that of P. clematidea. Heterogeneous P with AMF increased the suppression ability of B. pilosa but decreased that of P. clematidea. The interactive effects of AMF and soil P distribution on root foraging and nutrient uptake and competition differ among the four species and show invasive-native pair differences. These findings provide valuable insights into the interactive effects and highlight the context dependency of these interactions.