## 5 Conclusions  
This study used the InTEC model to simulate the spatiotemporal pattern of forest ecosystems' NEP in Zhejiang Province and analyzed their correlation with meteorological factors such as temperature, precipitation, relative humidity, and radiation. Studies have shown that the optimized InTEC model can better simulate the spatiotemporal distribution of forest ecosystems' NEP values in Zhejiang Province, and the correlation coefficient between the simulated NEP and observed NEP is up to 0.75. From 1985 to 2015, the forest ecosystem NEP of Zhejiang Province showed a rapidly increasing trend, with an annual average increase rate of 1.52 Tg-Cyr\({}^{-1}\), while forests in Zhejiang Province were carbon sources from 1985 to 1988. After that, the forest carbon sink ability gradually increased, and the annual average NEP increased to 393.91 gC\(\cdot\)m\({}^{-2}\)-yr\({}^{-1}\). The carbon sequestration capacity of forests in the  
Figure 13: The spatial distribution of the correlation relationships between forest NEP and (**a**) temperature, (**b**) precipitation, (**c**) relative humidity, and (**d**) radiation in Zhejiang Province from 2000 to 2015.  
east and southwest is higher than in the northeast plains. From 2000 to 2015, forests in Zhejiang Province were dominated by carbon sink forests. During this period, there was an extremely significant correlation between forest ecosystem NEP and precipitation, with correlation coefficients of 0.85, and there was a significant correlation between NEP and temperature and radiation, with the same correlation coefficient of \(-0.56\). However, there was only slight correlation between NEP and relative humidity. At the same time, the relative contribution rate of NEP to temperature, precipitation, relative humidity, and radiation shows that precipitation to NEP was the largest, reaching 61%, followed by temperature and radiation, which were 18% and 17%, respectively. The relative contribution rate of relative humidity was the smallest, at only 4%. During the period of 1985-1999, frequent man-made disturbance led to a weak correlation between NEP and temperature, precipitation, relative humidity, and radiation. This indicated that precipitation has a great impact on the carbon sequestration function of forest ecosystems in Zhejiang Province and that temperature and radiation have particular scientific significance for studying the ability of subtropical forests to cope with climate change.  
Conceptualization, H.D.; data curation, X.L., L.D., M.Z., N.H., T.L., and L.X.; methodology, J.Z. and F.M.; supervision, G.Z.; validation, F.M.; writing--original draft, J.Z.; writing--review and editing, H.D.  
The authors gratefully acknowledge the support of the National Natural Science Foundation (No. 31670644, U1809208), the State Key Laboratory of Subtropical Silviculture (No. ZY20180201), the Joint Research fund of Department of Forestry of Zhejiang Province, the Chinese Academy of Forestry (2017 SY04), and the Zhejiang Provincial Collaborative Innovation Center for Bamboo Resources and High-efficiency Utilization (No. S2017011).  
The authors gratefully acknowledge the supports of various foundations. The authors are grateful to the Editor and anonymous reviewers whose comments have contributed to improving the quality of this paper and we would like to acknowledge [PERSON] for her English editing of the article.  
The authors declare that they have no competing interests.