Occurrence of plant suppression gradients through common mycorrhizal networks across ecological groups during successional dynamics

Plants can utilize the common mycorrhizal network (CMN) as a pathway for competition, enabling the suppression of other plants through an asymmetric distribution of resources. This study aimed to assess the competitive dynamics of CMN originating from adult Brachiaria brizantha plants, juvenile Heliocarpus popayanensis, and juvenile Cariniana estrellensis on the growth of seedlings of these three species. Plants and seedlings were cultivated in substrates containing native arbuscular mycorrhizal fungi (AMF). Analysis of variance was conducted, and means were compared using the Tukey test. The results indicated that seedling growth of all three species was significantly suppressed by the CMN originating from adult B. brizantha, moderately suppressed by the CMN from juvenile H. popayanensis, and weakly suppressed by the CMN from juvenile C. estrellensis. While the seedlings of B. brizantha initially experienced suppression, they eventually developed and suppressed the juvenile plants of both H. popayanensis and C. estrellensis, leading to a reversal of the nutrient flux. This shift corroborated the mechanism of reciprocal reward. The study observed the formation of a gradient in seedling suppression, with the strength of suppression inversely correlated with the advancement of ecological plant groups during succession. The establishment of the seedling suppression gradient was associated with variations in photosynthetic potential, mycorrhizal responsiveness, and root colonization intensity by AMF. The competition dynamics mediated by the CMN affect the composition and diversity of plant communities over time, reinforcing the importance of mycorrhizal interactions in plant ecology and ecosystem management, particularly in restoration and conservation contexts.