Approach of land use zone for capital farmland protection based on spatial agglomeration pattern and boundaries modification

Abstract: Current studies are focused on the high quality farmland parcels identification and aggregation, yet have not considered the concentered and contiguous pattern required in management. As a result, the protected areas of farmland are fragmental in spatial distribution, which increases the difficulty in large-scale production and the risk of occupation by constructive land around. So the capital farmland protection zones need to be transformed from parcels preservation to land use zones in concept; and the zones, which are high-quality and concentrated and have clear outlines and the functions of guiding and separating farmland from constructive and ecological land, can contribute to the capital farmland conservation practice. This paper interprets that land use zone for capital farmland protection has 3 basic rules in zoning. Firstly, the farmland parcels should be almost high-quality with sound drain and irrigation facilities and good capacity to resist the disaster; secondly, zones should have coherence and be closed; and at last, zones should have explicit and unaffected boundary and be encircled by linear features like high-grade road and river, so that they can be convenient for management as the parks. Based on the principles above, this paper proposes the methods consisting of farmland comprehensive quality evaluation, spatial agglomeration of local Moran's I and buffer analysis to delimitate the protected areas of basic farmland, and takes Pinggu District, Beijing City as the case study. At first, it analyzes the comprehensive quality of the capital farmland by multi-factor evaluation and gradual modification method; the factors that are related with the natural quality, location accessibility, development stability and ecological security of the capital farmland are considered in evaluation, and the high-quality capital farmland plot are selected. Then based on the scores of farmland comprehensive quality, spatial agglomeration method of local Moran's I is used to define the spatial pattern of high-quality and low-quality farmland, and the key protection areas of capital farmland are preliminarily delimitated. At last, for the capital farmland protection zones, boundaries modified methods in buffer analysis are used in modification of key areas. Results show that, the average score of the comprehensive quality of the capital farmland in Pinggu district is 53.66, indicating the capital farmland quality is relatively fine. And based on the Moran's I and the local indicators of spatial association method, 4 spatial agglomeration patterns of the fine capital farmland and the other land are obtained, which are high-high, high-low, low-high and low-low pattern, and the high-high and low-high pattern are chosen to the key protection zones that are 11 568.93 hm2. And the final capital farmland protection zones are designed by linear elements such as roads and rivers adjacent to the key protection zones. There are 44 capital farmland protection zones in Pinggu District with the total area of 13 395.99 hm2, covering 80% of the capital farmland plots. The results indicate that the design approach of the capital farmland protection zones based on spatial agglomeration pattern is useful to form the high-quality and concentrated zone with clear outline, which can provide guidelines for the capital farmland protection planning and land use planning in practice.