Quantitative assessment of cultivated land use intensity in Heilongjiang Province, China, 2001–2015

Abstract

Cultivated land is a crucial resource for human survival and development. The sustainable use of cultivated land is the foundation for ensuring food security and maintaining social stability. The Chinese government has promulgated a series of policies to protect cultivated land, focusing on the quantity, quality, and health of cultivated land. However, these policies lack adequate focus on aspects such as the intensity and sustainable use of the cultivated land. Human appropriation of net primary production (HANPP) is an important method for measuring land use intensity and ecosystem sustainability. Based on the HANPP framework, this study estimated the cultivated land use intensity (CLUI) at a 1-km-scale in Heilongjiang from 2001 to 2015. Spatial autocorrelation models were used to analyse the spatio-temporal patterns and aggregation characteristics of CLUI, and correlation analysis model was used to reveal the influencing factors of CLUI in time and space. The results included the following: (1) Utilization intensity of wheat (CLUIwheat), maize (CLUImaize), and all crops (CLUIall) increased by 0.07, 0.44, and 0.26, respectively, and rice (CLUIrice) decreased by 0.07 over 15 years. However, in the long term, cultivated land with rice had a higher utilization intensity with an average of 1.54, followed by maize (1.46) and wheat (1.23), which were significantly higher than the global average CLUI (approximately 0.84). Meanwhile, crop type conversion (from wheat and corn to rice, and from corn to rice) could significantly increase CLUI. (2) CLUIall had significant spatial heterogeneity and spatial aggregation characteristics. The barycentre of high-value aggregation of CLUIall moved to the northwest, while the barycentre of low-value aggregation moved to the southwest during the study period. (3) Fertilizers, pesticides, and plastic mulch had a significant positive correlation with CLUI. Excellent natural conditions could withstand more human disturbance and had lower utilization intensity. (4) Implementing the "Storing Grain in Land and Technology" strategy and cultivated recuperation policy to solve the high utilization intensity should be a priority. Scientific cropping structure, suitable cropping system, and reasonable fossil energy input were effective means to reduce the CLUI and achieve sustainable land use. In addition, establishing CLUI monitoring networks was an effective measure to obtain CLUI dynamics in a timely manner.