Spatial distribution characteristics of arable land grade in Beijing-Tianjin-Hebei-Shandong Region

Abstract: Understanding the distribution characteristics of cultivated land grade in the Beijing-Tianjin-Hebei-Shandong region at different spatial scales can provide a theoretical basis for cultivated land quality protection and improvement, and the optimized spatial distribution of cultivated land. In this study, we analyzed the distribution characteristics of cultivated land quality grade in Beijing-Tianjin-Hebei-Shandong region based on the national collection results of annual database of the cultivated land quality in 2014 and the methods including area-weighted averages, spatial analyses and geo-statistical analysis. Firstly, the average cultivated land quality of the whole area, provinces (cities) and secondary index areas of Beijing-Tianjin-Hebei-Shandong region were calculated by the area-weighted averages method of cultivated land quality, and the characteristics of the average cultivated land quality at different scales were analyzed. Secondly, we analyzed the spatial distribution characteristics of the cultivated land quality in Beijing, Tianjin, Hebei and Shandong by ArcGIS software. Finally, we studied the aggregations features of the cultivated land aggregation in provinces (cities) by used the method of location index, definitely of the distribution characteristics of cultivated land in Beijing-Tianjin-Hebei-Shandong region. The results showed that the quality grade ranged from 4 to 15 with an average of 9.5, which was relatively higher than the national average. There was a great gap of cultivated land grade among the different provinces. The cultivated land grade in the Shandong provinces had a higher quality, which ranged from 7 to 9. However, that in Hebei provinces had a lower grade that ranged from 9 to 14. The cultivated land grade in the southeast counties was higher than the northwest. The cultivated land grade was significant different in the different agricultural grading zones. Cultivated land grade in Huang-huai-hai Plain was 5.7 higher than Dam mountain plateau. Concentration degree of cultivated land quality in the plain area was higher than the mountainous area. The main causes affecting the spatial difference of cultivated land quality in the Beijing-Tianjin-Hebei-Shandong region were the light temperature/climate, agricultural production conditions and socio-economic conditions further perturbed its differentiation law. At the same time, as the Beijing-Tianjin-Hebei-Shandong region across eight latitudes, the thermal conditions and water-heat combination gradually decreased from south to north, and soil, vegetation also underwent the corresponding zonal changes. Complex geomorphological types restricted distinctly the distribution of cultivated land quality. In the future, in order to protect cultivated land in the Beijing-Tianjin-Hebei-Shandong region, the "cultivated land -occupying and compensating balance policy" should be strictly implement, the scale of high-quality cultivated land should be strictly management, sandy land should be improved, adopted to realize important the concentration of farming fields are in pieces. This research provides a reference for policy making about regional comprehensive planning, regional cultivated land resource security, permanent prime farmland protection and delineation, cultivated land occupation, balance and land remediation.