# Dynamic Changes in and Driving Factors of Soil Organic Carbon in China from 2001 to 2020
## 4 Discussion
### Driving Factors for SOC  
#### 4.2.1 Impact of Climate Change on SOC  
Our study shows that temperature and precipitation within the study period were positively correlated with SOC in eastern and southern China, and the warm and humid climatic background promoted the continuous accumulation of SOC, which is consistent with previous studies ([PERSON] and [PERSON] (1999)). On the one hand, studies have shown that plants are an important source of SOC ([PERSON] and [PERSON] (1999); [PERSON] and [PERSON] (1999)), and increased temperature promotes plant productivity and the allocation of organic carbon to the subsurface ([PERSON] and [PERSON] (1999); [PERSON] and [PERSON] (1999)). In addition, increased precipitation improves soil moisture conditions, and a moist soil environment promotes microbial growth and reproduction, accelerates the decomposition and transformation of organic matter, and further increases the organic carbon content in the soil ([PERSON] and [PERSON] (1999); [PERSON] and [PERSON] (1999)).  
On the other hand, the contribution of temperature and precipitation to SOC accumulation is not absolute, and studies have shown that climate warming enhances soil respiration, leading to soil carbon loss ([PERSON] and [PERSON] (1999); [PERSON] and [PERSON] (1999)). Warmer temperatures also alleviate the temperature limitation of microbial intracellular and extracellular enzyme activities, increase the microbial availability of apoplastic material, and accelerate CO\({}_{2}\) release ([PERSON] and [PERSON] (1999); [PERSON] and [PERSON] (1999); [PERSON] and [PERSON] (1999)). This tends to occur at high altitudes and high latitudes. Our results also suggest a tendency for the accelerated loss of SOC in northeastern China in the context of global warming and humidification.  
Finally, it has been shown that when the temperature reaches a certain level, the higher the temperature, the slower the rate of carbon sequestration, even resulting in carbon loss ([PERSON] and [PERSON] (1999); [PERSON] and [PERSON] (1999)). In semi-arid and arid regions, moisture is a key factor limiting vegetation growth, which in turn significantly affects SOC accumulation ([PERSON] and [PERSON] (1999)). Under global warming, frequent extreme heat and drought events can exacerbate the loss of SOC ([PERSON] and [PERSON] (1999)). [PERSON] et al. showed that SOC in the arid northwestern region of China has decreased by 585.50 Tg, with an average decrease of 19.52 Tg C yr\({}^{-1}\), in the past 30 years and more ([PERSON] and [PERSON] (1999)). Consistent with previous studies, our study also demonstrates that in the arid and semi-arid Northwest China, the effects of temperature and precipitation on SOC exhibited significant variability, with temperature mainly having negative effects and precipitation playing a positive role. However, the effects of human activities are also not negligible, especially in the areas of the Maowuosu Desert, Loess Plateau, and Alashan, where SOC shows a continuous increase due to continuous afforestation and vegetation protection and restoration [23; 66; 67].