Objectives  To provide a scientific basis and reference for enhancing the carbon sequestration capacity of national ecological forests and improving protection and management policies.

  Methods  Using NPP data of the national ecological forests in Zhejiang Province between 2005 and 2020, we analyzed the spatiotemporal characteristics of NPP of the national ecological forests in Zhejiang Province by combining topographic, soil, climate, and attribute factors. We used linear regression and geodetector to explore the influencing factors.

  Results  The NPP mean value of the national ecological forests in Zhejiang Province from 2005 to 2020 was 735.9 g·c/m²; The NPP mean value of the ecological forests in the middle mountain was the highest, followed by low mountain and hill, while the NPP mean value of the ecological forests in the plain was the lowest. The area of the southern slope was larger than that of the northern slope, and the area of the western slope was nearly equal to that of the eastern slope. The NPP mean value of the ecological forests growth rate was higher on the western slope compared to the eastern slope. The highest NPP mean value of the ecological forests was observed in red clay, while the NPP mean value of the ecological forests in red earth was nearly equal to that in yellow earth. The lowest NPP mean value of the ecological forests was observed in limestone soil. The mean NPP value of the ecological forests under collective ownership was significantly higher than those under state-owned ownership. Additionally, the NPP mean value of second-level forests was significantly higher than that of first-level forests. Furthermore, the NPP mean value of artificially established forests was significantly higher than that of naturally established forests. The NPP value of Pinus taiwanensis ecological forests was significantly higher than that of other species, and the NPP value of species containing Pinus massoniana or high-density timber species was higher than that of other species. Finally, the NPP value of Quercus spp. ecological forests and other shrubs was the lowest.

  Conclusions  From 2005 to 2020, there was a gradual increase in the NPP value. The NPP value of the national ecological forests in the northwest of Zhejiang Province was lower than that in the southeast. The distribution of the ecological forest NPP value was greatly influenced by latitude, longitude, yearly precipitation, yearly mean temperature, species, and soil type. Moderate manual intervention was found to be conducive to increasing the ecological forest NPP value, provided that strict regulation was maintained.