Stand characteristics and ecological benefits of Chinese Fir, Chinese Cedar, and mixed plantations in the mountainous areas of the Sichuan Basin

•The forest productivity of mixed plantations was 18–39.5% greater than that of pure plantations.•Understory vegetation diversity in MCC was significantly higher than in PCL and PCF, by 15.8–20% and 13.2–35.7%, respectively.•The water conservation capacity of MCC is significantly higher (by 19.4–42.9%) than that of PCL and PCF.•Performance against the soil fauna diversity index was similar in all three stands.