Productivity and tolerance reveal the shift from competition to facilitation among multiple species under multiple stressors

• The shift from competition to facilitation occurs on stress-intolerant species. • The shift due to the acceleration or deceleration of productivity under high stress. • Positive feedback effect improves productivity of stress-intolerant species. Interspecific competition and facilitation play essential roles in community structure and have been widely demonstrated between pairwise species. However, little is known about how interspecific interactions among multiple species shift between competition and facilitation under multiple stressors. Here, we developed a plant community dynamic model to investigate how the biomass of three dominant species ( Ceratophyllum demersum , Hydrocharis dubia , and Phragmites australis ) shifts across total nitrogen ( TN ) and water depth ( WD ) gradients, further clarifying the interspecific interactions among these three species compared to those observed between pairwise species. The results were as follows: (1) interspecific competition shifted to facilitation with increasing TN stress, mainly affecting the stress–intolerant species; (2) this shift under TN and WD stressors occurred at lower TN levels than those observed under a single TN stress, and the shift occurred at higher TN levels among the three species compared to those observed between pairwise species. We suggest that: (1) the shift from interspecific competition to facilitation primarily relies on the strong positive feedback effect that enhances low productivity under high stress; (2) the threshold for this shift is influenced by the acceleration or deceleration of productivity under high stress due to multiple stressors and species, respectively. Our study proposes adaptation mechanisms from the perspective of interspecific interactions among multiple species, which can be explained by the productivity and tolerance of these species under multiple environmental stressors. This research provides novel ideas and methodologies for gaining insight on the co-existence of multiple species and the stability of plant community systems.