FWB_P_Apr_25_0195_appendix

Water-filled treeholes provide an ideal system to separate the roles of resources and abiotic conditions in community assembly, and we hypothesized that resource-related niches more strongly drive niche differentiation than condition-related niches.We independently and jointly manipulated resource levels (cotton powder) and condition variables (plastic leaves) and analyzed species-specific responses using a trait-based SDM.Smaller species responded strongly to both manipulations and increased under resource addition, whereas larger species (e.g., <i>Tripteroides bambusa</i>) showed weak responses to single treatments but declined under combined treatments.Interactions between resource and condition niches showed additive and synergistic effects, and species responses were more strongly linked to resource niches, emphasizing their key role in community assembly.These findings highlight the importance of distinguishing resource and condition niches to advance our understanding of community assembly and niche differentiation.