Abstract: Taking the 2009-2019 statistical yearbook data of Yan'an City as the data source, using the PSR model, a total of 31 factors were selected from the three levels of pressure, state and response to construct a land ecological security evaluation index system, and the entropy method was used to determine the weights of each index. Based on the land ecological security pressure index, state index, response index and comprehensive index, the dynamic change trend of land ecological security in Yan'an City from 2009 to 2019 was systematically evaluated, and a factor obstacle model was established to identify the main constraints on the ecological security of its land. The results showed that from 2009 to 2019, the land ecological security pressure index in Yan'an decreased from 0.314 6 to 0.128 9, a decrease of 59.03%, the status index rose from 0.049 2 to 0.235 7, an increase of 379.07%, and the response index rose from 0.034 0 to 0.177 8, an increase of 422.94%. From 2009 to 2019, the overall comprehensive index of land ecological security in Yan'an showed a fluctuating upward trend, rising from 0.397 8 to 0.542 4, an increase of 36.35%; according to the classification, the ecological security level of land in Yan'an City increased from less safe to safer. The amount of agricultural fertilizer application, raw coal production, and the number of cattle and sheep at the end of the year were the main limiting factors affecting the ecological security of land in Yan'an.

Key words: land ecological security, PSR model, entropy method, barrier degree, Yan'an City