# Impacts of Land-Use Change from Primary Forest to Farmland on the Storage of Soil Organic Carbon
## 5 Conclusions  
Through the comprehensive analysis of SOC storage changes after the conversion of primary forest to farmland, the main conclusions are as follows:  
1. After the conversion of primary forests into farmland, there is a significant decrease in the storage of soil organic carbon (SOC). This indicates that land use change has a significant impact on SOC content. Primary forests are complex and stable ecosystems that contain a large amount of organic carbon in the soil. However, once the primary forests are cleared for agriculture, the soil is exposed to the atmosphere and human activities, resulting in an accelerated decomposition rate of SOC and a sharp decline in SOC storage.
2. When primary forests are converted into farmland, temperate forests experience greater loss of SOC compared to tropical forests, while the loss of SOC in deeper soil layers is relatively smaller. This suggests that the extent of SOC loss after land use change depends on the type of forest and the soil depth. Temperate forests and tropical forests differ in soil characteristics, climate conditions, and vegetation composition. Therefore, after temperate forests are converted into farmland, the influence of climate change and soil characteristics leads to a more significant loss of SOC. Additionally, SOC decomposition rates are relatively slower in deeper soil layers, resulting in less severe SOC loss compared to shallow soil layers.  
The findings of these conclusions help us understand the dynamics of SOC changes after the conversion of primary forests into farmland and provide scientific guidance for agricultural management and land conservation. During the process of land conversion into farmland, implementing soil conservation measures, adopting appropriate fertilization and nutrient management strategies, selecting suitable cultivation methods, and promoting ecosystem restoration can help reduce the rate of SOC loss, promote soil health, and achieve sustainable agricultural development.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app14114736/s1](https://www.mdpi.com/article/10.3390/app14114736/s1)]([https://www.mdpi.com/article/10.3390/app14114736/s1](https://www.mdpi.com/article/10.3390/app14114736/s1)), Table S1: List of studies included in this meta-analysis.  
Conceptualization, X.Y., C.X. and Y.G.; methodology, X.P., H.C. and S.L.; software, C.L., L.C. and X.Z.; validation, J.Z. and X.Y.; formal analysis, C.X.; investigation, Y.G.; resources, C.X., Y.G., S.L. and C.L.; data curation, X.Z.; writing--original draft preparation, C.X., Y.G. and X.Y.; writing--review and editing, C.X., Y.G. and X.Y.; visualization, X.Z.; supervision, X.Y.; project administration, X.Y.; funding acquisition, H.C. and X.Y. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Natural Science Foundation of Fujian Province, grant number 2022J01604 and 2021J01117; and by Natural Resources Science and Technology Innovation Project of Fujian Provincial Department of Natural Resources, grant number KY-110000-04-2021-005.  
Not applicable.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
Authors would like to thank the anonymous reviewers for their comments and suggestions that improved this manuscript.  
The authors declare no conflicts of interest.