In science education, the abstraction and complexity of scientific concepts are usually stumbling blocks that prevent students from learning science. Recently, augmented reality (AR) has offered transformative potential to support scientific concept learning by visualizing scientific phenomena and enhancing students' experiences. However, the lack of appropriate pedagogical scaffolds might not ensure effective learning in the AR learning environment (ARLE). In this study, we developed an AR-based learning tool (PeachBlossom) to support students' scientific concept learning and integrated the concept map strategy into AR learning activities. We conducted a quasi-experiment to examine the educational effectiveness of the concept map strategy on students' mental models and cognitive load in an ARLE. Eighty-five seventh graders (aged 12-14) from Central China were assigned into two groups (AR and AR with a concept map [ARCM]). The results showed that when considering students' prior mental models, the positive effect of the concept map strategy was found only in students with low and medium levels of prior mental models. In addition, the concept map strategy reduced students' mental effort but did not significantly affect students' mental load. This study emphasises the importance of considering students' prior mental models when implementing the concept map strategy in ARLEs.