## 4 Discussion
### Differentiated Impacts of Forest Cover Change and CDHEs on Forest Carbon Dynamics  
The net carbon loss due to CDHEs and forest cover changes between 2000 and 2022 showed significant differences in the two regions. The discrepancy might be attributed to variations in city types. Urbanization would directly affect the forest's carbon storage [79]. [PERSON] et al. [80] believed that urban expansion caused by urbanization causes the removal of forest vegetation, and the carbon absorption capacity of carbon sinks rapidly declines. At the same time, China is undergoing a rapid urbanization process with low vegetation coverage, and large areas of forest vegetation are cleared to meet the needs of urban population growth and economic development. As a significant financial center city in the Yangtze River Delta region, Nanjing's urbanization process is higher [81]. With the deepening of this process, the population of Nanjing has shown a sharp growth trend [81]. The surge in population is placing higher demands on food supplies, which in turn is driving the demand for farmland of a specific size. In this context, the land use pattern in the Nanjing area has changed significantly, especially since the conversion of forest to farmland has become frequent [82]. Therefore, the intensification of urbanization in Nanjing significantly impacts forest carbon storage through population growth and land use patterns. This also explains why forest cover change has become the main factor leading to forest carbon loss in Nanjing. This is consistent with [PERSON] et al.'s [83] belief that urban sprawl is the leading cause of carbon emissions in the eastern seaboard.  
Shaoguan, as a typical forest city in Guangdong Province, has a low urbanization level and a high forest cover. Human activity is relatively minimal. China has rolled out a series of policies aimed at ecological conservation in the south, such as the South China Timber Production Plan, which somewhat offset the carbon loss caused by forest cover change in Shaoguan [84]. Shaoguan is in the northern region of Guangdong, south of the Nanjing Mountains. The Nanjing Mountains block precipitation formation, partly leading to drought. Additionally, the karst geology in the northern Guangdong region exhibits significant ecological fragility, frequently encountering problems of soil and water loss [85; 86]. This unique geological structure lacks good water storage and precipitation replenishment capabilities, which may reduce surface water flow and limit evaporation during the growth process of young forests and artificial forests. This also helps explain why forest carbon loss in the Shaoguan area is mainly affected by CDHEs. It should be noted that there is a strong link between deforestation in low latitudes and climate warming [87; 88]. Global warming has further promoted the frequent occurrence of CDHEs, forming a vicious circle [89]. It is suggested that the importance of forest cover changes together with CDHEs in low-latitude regions needs to be considered.  
Forest management policies should be developed for different urbanization levels and geological conditions [90]. In highly urbanized areas, supervision of land use change should be strengthened to prevent forest carbon loss caused by overdevelopment [91]. In areas with high forest coverage, the control of human disturbance should be strengthened to reduce forest carbon loss. We will improve the protection of ecologically fragile areas to prevent soil erosion and ecological degradation [92; 93].