## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Indicator**} & **Value** & \multirow{2}{*}{**Study Region**} & \multirow{2}{*}{**Methods**} & \multirow{2}{*}{**Source**} & \multirow{2}{*}{**Reference**} \\  & **(gC\(\cdot\)m\({}^{-2}\).yr\({}^{-1}\))** & & & & \\ \hline \hline
1966–2257 & Southern China & Model & RFR-LUE & [PERSON] et al. (2017) [55] \\ \hline
1430–1619 & Southern China & Model & EC-LUE & [PERSON] et al. (2013) [56] \\ \hline
1174.65–1982.54 & Southern China & Model & MODIS, PML, and VPM & [PERSON] et al. (2022) [57] \\ \hline
1211–1604 & Southern China & Model & MODIS algorithm parameterized by FLUXNET sites & [PERSON] et al. (2017) [58] \\ \hline
1509 \(\pm\) 734 & Southern China & Model & VIP & [PERSON] et al. (2018) [59] \\ \hline
3150 & Tropical forests in Malaysia & Model & VPISIT & [PERSON] et al. (2011) [60] \\ \hline
3551 \(\pm\) 160 & Global tropical forests & Observation and model & Data synthesis & [PERSON] et al. (2007) [61] \\ \hline GPP & 1709 \(\pm\) 80 & Sites in Southern China & Site observation & FLUXNET & [PERSON] et al. (2019) [62] \\ \hline
1826 & Sites in Southern China & Site observation & FLUXNET & [PERSON] et al. (2017) [58] \\ \hline
3040–3140 & Tropical forests in the Amazon & Site observation & FLUXNET & [PERSON] et al. (2009) [63] \\ \hline
4860 & Tropical forests in the Amazon & Site observation & FLUXNET & [PERSON] et al. (2024) [64] \\ \hline
4010 & Tropical forests in West African & Site observation & In situ biometric measurements & [PERSON] et al. (2024) [65] \\ \hline
1314 & Caatinga ecosystem in Brazil & Site observation & FLUXNET & [PERSON] et al. (2021) [66] \\ \hline
2144 \(\pm\) 123 & Savanna ecosystem in North Australia & Site observation & FLUXNET & [PERSON] et al. (2021) [67] \\ \hline
1216.66 & Jiangsu Province, China & Model & BEPS & This study \\ \hline
687 & Southern China & Model & BEPS & [PERSON] et al. (2024) [68] \\ \hline
1018 & Southern China & Model & DLEM & [PERSON] et al. (2015) [69] \\ \hline
891 & Southern China & Model & M-SDGVM & [PERSON] et al. (2010) [70] \\ \hline
721 & Southern China & Model & CEVSA & [PERSON] et al. (2003) [71] \\ \hline
417.9 & Southern China & Model & CASA & [PERSON] et al. (2005) [72] \\ \hline
864 \(\pm\) 96 & Global tropical forests & Site observation and model & Data synthesis & [PERSON] et al. (2007) [61] \\ \hline
1300 \(\pm\) 50 & Evergreen forests in Ghana, West Africa & Site observation & In situ biometric measurements & [PERSON] et al. (2017) [73] \\ \hline
1000–1440 & Tropical forests in the Amazon & Site observation & FLUXNET & [PERSON] et al. (2009) [63] \\ \hline
536.27 & Jiangsu Province, China & Model & BEPS & This study \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of the GPP, NPP, and NEP results from this study to the existing observational and modeling records. From our study, it can be seen that both the area and C sequestration of PFs have increased over the past decades across the study region, highlighting their beneficial role in mitigating climate warming. The rapid expansion of PFs in Jiangsu after 2015 is closely linked to national and provincial mitigation policies and programs. Major afforestation programs launched between 2016 and 2020 which emphasized increasing forest cover as an important approach to fulfilling the national C neutral target in the upcoming decades [27]. These top-down initiatives were supported by economic incentives, such as subsidies and grain-to-green payments, encouraging the conversion of marginal farmland into forests and integrating afforestation into regional planning [28]. Meanwhile, ecological restoration efforts, including coastal shelterbelt planting and wetland forest restoration, e.g., in Yancheng City, have facilitated forest establishment along Jiangsu's coastal areas [78; 79; 80]. In addition, initiatives such as the promotion of \"Green and Beautiful Villages\" and the designation of \"National Forest Cities\" have motivated local governments to expand urban and peri-urban tree planting [81; 82].