粮食安全背景下东北典型黑土区耕地压力动态变化及趋势分析

东北黑土区耕地肩负国家粮食安全的重任,目前其耕层变浅、质量下降等耕地压力问题逐渐显现。为了掌握区域尺度上黑土耕地压力分布及其动态变化,保护黑土资源,该研究选取21个典型黑土县区,采用修正的耕地压力指数模型、灰色-BP组合预测模型分析测算耕地压力指数及耕地压力变化趋势,并依此对现有黑土地保护政策提出细化建议。结果表明：1）耕地压力指数受到耕地质量（负向影响）、实际人均耕地面积（负向影响）、粮食安全保障范围（正向影响）、社会经济发展水平（负向影响）等综合影响,得出典型黑土区域耕地压力的时空变化特征。2）耕地压力可表征粮食安全压力,但粮食安全压力无法准确反映耕地压力状况。3）耕地压力变化趋势为整体向好,局部堪忧。2004－2019年21个研究单元中除拜泉县以外耕地压力均下降至安全范围,2020－2024年有15个县区处于无压力平稳区或压力下降区,其余县区处于不同程度的压力状态。最后,对于不同压力区域提出因地制宜的黑土地保护政策建议。研究结果可为缓解黑土耕地压力、实现国家粮食安全提供科学依据。

Dynamic change and trend analysis of cultivated land pressure in typical black soil areas of Northeast China under food security

The northeast black soil region has been one of the most important main grain producing areas and commodity grain production bases in China. A great task is to realize the national grain supply and security. The typical black soil has the excellent soil characteristics and high fertility. However, the high-intensity utilization mode of arable land is widely used in the grain production under the ever-increasing demand with the acceleration of industrial development and urbanization. Although this approach can improve the grain output in a short period of time, the cultivated land pressure (such as shallower surface layer and quality decline) is gradually appeared in the black soil area. Therefore, it is very urgent to protect the black soil areas, as issued by the Outline of the Plan for the Protection of Black Soil in Northeast China (2017-2030) in 2017. This study aims to clarify the cultivated land pressure in the black soil area of Northeast China under different scopes of food security. The 21 typical black soil counties and districts were selected using the statistical data from 2004 to 2019. A modified model of cultivated land pressure index was established to calculate the cultivated land pressure index. The grey-BP network combined with the forecasting model was used to predict the change trend of cultivated land pressure in the next five years. Some suggestions were also proposed for the black land protection. The results show: 1) The cultivated land pressure was generally better in the typical black soil area of Northeast China from 2004 to 2019. But, there were still some areas with the "false security" phenomenon, due to the high intensity of cultivated land use pattern. The severe pressure constraints were found in the black soil of the cultivated land. The dynamic change of cultivated land pressure was negatively correlated with the quality of cultivated land, actual per capita cultivated land area, as well as social and economic development level. Therefore, the cultivated land pressure gradually increased with the expansion of food security. 2) A typical northeast black soil area of cultivated land was found to effectively relieve the national pressure from 2020 to 2024. But, the low and medium pressure level was observed in the Nehe, Changtu counties, whereas, the Baiquan county was in a high pressure rise. The Yian County was depended mainly on the rural social and economic development. Specifically, the pressure was in the good condition before 2023, but the subsequent trend indicated the pressure warning. 3) The pressure of cultivated land can be expected to represent the pressure of food security, but the pressure of food security cannot accurately reflect the pressure of cultivated land. Short-term high-intensity use of cultivated land can lead to the "deceptive" performance of cultivated land pressure. A low pressure of cultivated land was found at first, but the long-term role failed to ensure the food security with the gradual reduction of the fertility. 4) The measurement demonstrated that the current refined and improved policy was achieved in the pilot implementation of soil protection and utilization. Consequently, the pressure of arable land can be effectively relieved, even though there was a certain lag in the project. The index of cultivated land pressure was divided into four levels. Different protection suggestions were proposed to adjust the measures for the better policy benefits, according to the local conditions in the various soil pressure areas.