## 4 Discussion  
Using multisource remote sensing data, this study examined the role of vegetation change on the terrestrial carbon uptake in a subtropical humid area, which would enhance our knowledge in the physical mechanism and support the land planning and eco-environment management. Results revealed that the vegetation greening enhanced the carbon sink level of the Dongting Lake Basin in the past two decades. In addition, the ecological conservation scenario could offset the potential decrease in future carbon uptake resulting from increased anthropogenic activities by 0.05 \(\times\) 10\({}^{7}\) t.  
LUCC plays an important role in the terrestrial carbon uptake at regional and global scales. Previous studies warned that global deforestation weakened the magnitude of \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Cultivated Land** & **Foresitland** & **Grassland** & **Water Area** & **Urban Land** & **Unused Land** \\ \hline Present Situation of Land & 80,336 & 149,120 & 19,826 & 7169 & 6852 & 482 \\ \multicolumn{1}{c}{} & Natural development & 79,351 & 146,559 & 19,069 & 8144 & 10,319 & 343 \\ \multicolumn{1}{c}{} & Ecological protection & & & & & \\ priority scenario in 2030 & 80,032 & 146,980 & 19,151 & 8167 & 9109 & 346 \\ \multicolumn{1}{c}{} & Economic development & & & & & \\ priority scenario in 2030 & 78,908 & 146,365 & 19,019 & 8114 & 11,034 & 345 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Area of different land use types under multi-scenario simulation (km\({}^{2}\)). \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Cultivated Land** & **Foresitland Carbon** & **Grassland Carbon** & **The Total of** \\  & **Carbon Uptake** & **Uptake** & **Uptake** & **Carbon Uptake** \\ \hline Present Situation in 2020 & 2.10 & 5.18 & 0.65 & 7.94 \\ \multicolumn{1}{c}{} & Natural development & & & \\ scenario in 2030 & 2.08 & 5.09 & 0.63 & 7.80 \\ \multicolumn{1}{c}{} & Ecological protection priority & & & \\ scenario in 2030 & 2.10 & 5.11 & 0.63 & 7.83 \\ \multicolumn{1}{c}{} & Economic development & & & \\ priority scenario in 2030 & 2.07 & 5.09 & 0.62 & 7.78 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Carbon uptake of different scenarios in the Dongting Lake basin in 2030 (\(\times 10^{7}\) t C). Figure 10: Comparison of vegetation carbon uptake in the Dongting Lake basin under different scenarios (\(\times 10^{7}\) t C). the terrestrial carbon uptake in recent decades [44; 45; 46]. Our work suggested that the degradation might be mitigated in the subtropical regions. The latest works also showed an overall greening trend at the global scale, particularly of China and India [47; 48; 49], which would therefore be expected to be an increased terrestrial carbon uptake in the foreseeable future. On the other hand, a contradiction always remains between socioeconomic development and eco-environment conservation. Urbanization unavoidably invaded the natural lands (i.e., the farmland, grassland, and forest) for the target of socioeconomic development [50], leaving great pressure on the terrestrial carbon uptake. Despite this, the ecological protection priority scenario would help to minimize the negative impact of urbanization. In this study, the regional carbon uptake would decrease in all the scenarios of recent decades. However, the magnitude of the carbon uptake decrease is minor in the ecological protection priority scenario, which strongly meets the sustainable goal for balancing socioeconomic development and eco-environment conservation. However, the advances in new technologies will have a new impact on the management of carbon sinks in the future. For example, the reduction in the cost of wood biochar would help to improve the biological carbon sequestration for carbon sinks management [51]. Moreover, although the application of solid biofuel technology has the potential to reduce the dependence on fossil fuels [52], the relationship is complex [53; 54].