Evaluation of exploitation suitability of unutilized arable lands in ecologically fragile areas — A case study of Datong City, Shanxi Province

Datong City is in Northwest China. As a main coal production base, the city is in a relatively fragile ecological environment region. Human activity has greatly affected land ecological environment in this region. This paper used Fuzzy analysis to regionalize ecological fragility of Datong City based on administrative districts. This was important for the evaluation of exploitation suitability of unutilized arable lands in different areas of the city. The indicators for regionalization of ecological fragility were natural factors, such as those involved in terrain, physiognomy, meteorology and hydrology, and artificial factors, such as those involved in land use, society, and economy. The weights of indicators were decided by using AHP method and the ecological fragility was classed into four level, which were micro, slight, moderate and severe levels. The evaluation results showed that Nanjiao District, Yanggao County, Zuoyun County and Tianzhen County were severe ecologically-fragile regions. Hunyuan County was a moderate ecologically-fragile region. Then Guangling County was a mild ecologically-fragile region. Xinrong District, Datong County and Lingqiu County were weak ecologically-fragile regions. On the base of regionalization of ecological fragility of the city, the exploitation suitability of unutilized arable lands was evaluated by using the regulated classification of agricultural lands combined with environmental conditions. The evaluation index system was consisted of factors of site, soil, hydrothermal and ecology with a total of eleven indexes. The weights of indexes were decided according to their importance, and the suitability coefficient was calculated. The results showed that 84.09% (468 692.59 hm²) of unutilized arable lands in the region was suitable for cultivation. About 43.77% (205 165.81 hm²) of the unutilized arable lands was in the weak ecologically-fragile region. Also the areas of unutilized arable lands in the mild, moderate and severe ecologically-fragile regions were 52 392.84 hm² (11.18%), 69 427.45 hm² (14.81%) and 141 706.49 hm² (30.23%), respectively. Unutilized arable lands with high suitability for cultivation in the weak ecologically-fragile region were given exploitation priority. Unutilized arable lands with relative suitability for cultivation in the weak, micro-level fragility were a viable alternative. Unutilized arable lands with high suitability for cultivation in mild and severe ecologically-fragile regions were not considered for exploitation.