## 5 Conclusions  
In view of the spatial distribution of rocky desertification, this paper studies the information extraction technology of rocky desertification research hot regions based on literature text mining and then analyzes the spatial distribution of research hot regions on rocky desertification in China and the applicable scenarios of the analysis methods of research hot regions. The main conclusions are as follows:  
1. Based on the CNKI knowledge database, using the web crawler, research information can be obtained quickly and easily in a short time; then, through text parsing, toponym identification and matching, hotness metering and other technologies and algorithms, the research hot regions on rocky desertification in China can be identified effectively.
2. The research hot regions of rocky desertification in China are mainly distributed in Guizhou, Yunnan and Guangxi Province. There are 108 counties with 245.7 thousand km\({}^{2}\) that belong to moderate, high and very high level of research hotness, especially in Bijie, Liupanshui, Guiyang, Anshun, Southwest Guizhou Autonomous Prefecture, Buyi and Miao Autonomous Prefecture of QianNan, Qiandongnan Autonomous Prefecture, Qiandongnan Miao and Dong Autonomous Prefecture in Guizhou Province, Hechi, Baise, Nanning, Guilin in Guangxi Province and Zhaotong in Yunnan Province.
3. The research hot regions on rocky desertification have good spatial consistency with the sensitive areas of rocky desertification. The two spatial distributions show that the areas of central Guizhou, eastern Yunnan and northern Guangxi are rocky desertification-prone areas and research hot regions. The county unit coincidence rate of the two spatial distributions is 48% and the prefecture unit coincidence rate is 85%. A combination of high-sensitivity and low-intensity research on rocky desertification has emerged in the four regions--Qionglai Mountain-Liangshan Area of Sichuan, Wushan-Shennongjia Area of Hubei, Hengduan Mountain Area of western Yunnan and Dupangling Area of southern Hunan--because of topography, vegetation coverage, degree of accessibility, human influence and other factors.
* Strong rocky desertification processes are mostly found in areas with high sensitivity to rocky desertification and easily disproportionate ecosystems and such areas usually have higher research frequency and vice versa. Although there is a close connection between the rocky desertification area and the rocky desertification research hot regions, there were similar characteristics in terms of incomplete matching concepts, space and time. The rational application of the differences in the spatial distribution of the two can improve the spatial and temporal pertinence of rocky desertification prevention and control planning, engineering governance and scientific research.  
[PERSON]. ([PERSON]) designed the idea and methodology; [PERSON]. ([PERSON]) and [PERSON] implemented the idea, performed the experiments and preliminarily analyzed the results; and all authors drafted and revised the paper.  
This research was funded by [National Key Research and Development Plan Program in China] grant number [2016 YFC0503701, 2016 YFB0501502], [Strategic Priority Research Program of Chinese Academy of Sciences] grant number [XDA19040301, XDA20010202],and [Key Project of High Resolution Earth Observation System in China] grant number [00-Y30B14-9001-14/16].  
The authors declare no conflict of interest.