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Sloping farmland has been one of the most important parts of cultivated land in the hills and mountains areas. It is a high demand to clarify the evolution characteristics and driving factors of the temporal and spatial pattern of sloping farmland, in order to rationally utilize resources and ecological functions. This study aims to reveal the spatial distribution characteristics and driving factors of sloping farmland in Chongqing City in southwest China. The aspects covered the temporal and spatial change characteristics, cold and hot spot patterns, as well as the driving factors of sloping farmland. Firstly, the local spatial autocorrelation (LISA) and cold hot spot were selected to determine the local spatial agglomeration characteristics of sloping farmland using the remote sensing data from 2000 to 2018. Secondly, the transfer of land use was obtained to overlay the land use data of each period. A transfer matrix of land use was then used to determine the transfer direction of sloping farmland. Finally, four dimensions were selected as the indicators, including the natural environment foundation, social living conditions, economic development level, as well as policy and institution. A geodetector was then used to determine the driving mechanism of sloping farmland change. The results showed that: 1) The area of sloping farmland decreased by 2.40% and 22 300 km2 in 2018, accounting for 59.35% of the cultivated land, compared with 2000. The average annual change dynamic degree of sloping farmland was greater than 1% in the six districts and counties (Yuzhong, Jiangbei, Jiangjin, Nan'an, Dadukou, and Shizhu). There was an outstandingly different change trend of sloping farmland areas in the different districts and counties. 2) Sloping farmland was significantly transferred from the forest land, grassland, paddy field, and construction land, where the transfer out and transfer in were generally balanced during the 18 years. The sloping farmland returning to the forest land was mainly concentrated in the regions of Shizhu, Wulong, Fengdu, and Yunyang counties in the Qin-Daba and Wuling Mountainous Areas. The area of sloping farmland showed a small decrease trend in the process of land use transfer. 3) There was significant heterogeneity of local spatial autocorrelation in the sloping farmland. The area of sloping farmland in most regions was in the state of high-high and low-low aggregation. The hot spots were concentrated in the northeast of the study area, whereas, the cold spots were distributed in the west and the main urban areas. 4) The factors in the forestry output value, per capita net income of rural residents, grain yield, rural employees, agriculture, forestry, and water expenditure greatly contributed to the slope farmland change, most of which were nonlinear and two-factor enhancement. Among them, the interactive driving factors with the greater explanatory power were the grain yield/slope (2005, 0.927), and per capita net income of rural residents/resident population (2018, 0.910). The leading factors of spatiotemporal characteristics were ranked as economic development, policy regulation, farmers' income, urban expansion, and socio-economic factors. A relatively less impact on the sloping farmland was found in the natural factors, including the altitude and rainfall. The findings can provide a scientific basis for the protection and pattern optimization of slope farmland in the mountainous and hilly areas of southwest China. [ABSTRACT FROM AUTHOR]

Cultivated land being an essential natural resource, has been increasingly occupied in the last 60 years with the acceleration of urbanization. It is necessary to be careful in land use, in order to ensure food security and human existence. In addition, the quality degradation of cultivated land has seriously threatened to food security due to the misuse of land. Slope farmland, one type of cultivated land, is widely distributed in the plateau and mountain areas in the central and western China. Scientific quality evaluation of slope farmland is closely related to local food security and ecological environment, further to implement national protection schemes, such as the “Trinity” of quantity, quality and ecology. However, there are some features of slope farmland, such as wide distribution, large slope, soil erosion, frequent seasonal drought, low soil quality, to make accurate evaluation difficult. The evaluation index and model are also lacking. Taking the slope farmland in Yunnan as a research area, this study aims to construct a quality evaluation system of slope farmland based on the framework of “element demand regulation”. The 30 m × 30 m grid (pixel) was selected as an evaluation unit for the comprehensive weight. The quality of slope farmland was evaluated quantitatively, together with its characteristics of spatial distribution. The results showed that: 1) Index system of the Minimum Data Set (MDS) in quality evaluation of slope farmland consisted of 14 indexes, including the effective thickness of soil layer, arable layer thickness, bulk density of soil, soil texture, pH value of soil, organic matter, effective phosphorus, available potassium, accumulated temperature (≥10 ℃), field regularity, contiguity, amount of rainfall, assurance rate of irrigation, and field slope. 2) Slope farmland Integrated Fertility Index (SIFI) was distributed between 0.36 and 0.81, with an average value of 0.59. Most evaluation units of SIFI was less than 0.6, showing a significant difference (P<0.05). The SIFI size relationship between five types of soil in slope farmland were ranked in order: Lateritic red earths, Red earths, Purplish soils, Yellow earths, Yellow-brown earths. SIFI increased with the elevation in the range of 0-1 000 m, while decreased larger than 1 000 m, indicating the variation of SIFI was related to the range of elevation. 3) The quality of slope farmland can be Grade 6, 5, 7 and 4, according the national standard. Specifically, the quality of slope farmland was relatively high Grade 4 and 5 at the southern border, central, southeast, and western Yunnan, whereas, northeast and northwest Yunnan indicated low Grade 6 and 7. The Lorenz curve of quality grade showed a pattern of “S-type” distribution in different regions, indicating a low grade in Yunnan province. This finding can provide a scientific basis to improve the quality evaluation system of slope land, thereby to efficiently implement geological regulation of slope farmland. [ABSTRACT FROM AUTHOR]

Slope farmland is an important part of cultivated land resources in hilly areas of China. Identifying the spatio-temporal distribution and evolution characteristics of slope farmland resources is of great significance for rational planning and utilization of slope farmland resources and water and soil ecological environment construction. In this paper, using the land use data for 7 time points from 1980 to 2015, based on GIS spatial analysis technology, dynamic degree model, kemel density estimation and landscape pattern index model, the spatio-temporal distribution pattern and evolution law of slope farmland in Yunnan for nearly 35 years were quantitatively analyzed. The results showed that: 1) the area of slope farmland in Yunnan was 472.55×104 hm², accounting for 69.79% of the cultivated land area, and the average slope was 15.62°. The relationship between the area ratio of slope farmland in different agricultural divisions was: Southwestern Yunnan>Northeastern Yunnan>Northwestern Yunnan>Southern fringe>Western Yunnan> Southeastern Yunnan>Central Yunnan, and the average slope size relationship was: Northwestern Yunnan>Southwestern Yunnan>Northeastern Yunnan>Western Yunnan> Southern fringe >Southeastern Yunnan > Central Yunnan. 2) In the past 35 years, significant dynamic transfers had occurred in slope farmland, forest land, grassland and paddy fields, but the process of transfer in and out was generally balanced, and the area of slope farmland has a slight increase trend during the process of land use transfer. 3) The slope of most slope farmland was more than 8°, and the proportion of slope farmland with slope >15° was 78.54%. The area of slope farmland with different slopes in the past 35 years had a dynamic process. It showed an increasing trend for the slope farmland area with slope <15°, while decreasing trend for the slope farmland area with slope >15°. The area of slope farmland with different slopes has the dynamic process of “decreased→increased→decreased” or “decreased→increased→ decreased→increased”, and the fluctuation degree of >25° slope farmland was the largest. 4) With the evolution of spatio-temporal distribution of slope farmland in the past 35 years, the distribution characteristics of kemel density value in slope farmland have changed, but the change range was small. The distribution of slope farmland in most areas was in low-density value, and the area of high-density value was the smallest. Slope farmland distribution clusters were represented by four significant distribution zones: the Lincang distribution zone, the Lincang-Xishuangbanna distribution zone, the Pu’er distribution zone and the Zhaotong distribution zone. 5) Among the eight types of land use, the landscape dominance of slope farmland was in the middle position, and the fragmentation characteristics of slope farmland were the most significant among all land use types. In the past 35 years, the degree of fragmentation of slope farmland landscape has decreased, and the degree of contiguous use of slope farmland has been strengthened. The research results can provide theoretical support for the rational planning and utilization of sloping farmland and soil and water ecological environment protection in Yunnan. [ABSTRACT FROM AUTHOR]

Slope farmland is an important part of cultivated land resources in hilly areas of China. Identifying the spatio-temporal distribution and evolution characteristics of slope farmland resources is of great significance for rational planning and utilization of slope farmland resources and water and soil ecological environment construction. In this paper, using the land use data for 7 time points from 1980 to 2015, based on GIS spatial analysis technology, dynamic degree model, kemel density estimation and landscape pattern index model, the spatio-temporal distribution pattern and evolution law of slope farmland in Yunnan for nearly 35 years were quantitatively analyzed. The results showed that: 1) the area of slope farmland in Yunnan was 472.55×104 hm2, accounting for 69.79% of the cultivated land area, and the average slope was 15.62°. The relationship between the area ratio of slope farmland in different agricultural divisions was: Southwestern Yunnan>Northeastern Yunnan>Northwestern Yunnan>Southern fringe>Western Yunnan> Southeastern Yunnan>Central Yunnan, and the average slope size relationship was: Northwestern Yunnan>Southwestern Yunnan>Northeastern Yunnan>Western Yunnan> Southern fringe >Southeastern Yunnan > Central Yunnan. 2) In the past 35 years, significant dynamic transfers had occurred in slope farmland, forest land, grassland and paddy fields, but the process of transfer in and out was generally balanced, and the area of slope farmland has a slight increase trend during the process of land use transfer. 3) The slope of most slope farmland was more than 8°, and the proportion of slope farmland with slope >15° was 78.54%. The area of slope farmland with different slopes in the past 35 years had a dynamic process. It showed an increasing trend for the slope farmland area with slope <15°, while decreasing trend for the slope farmland area with slope >15°. The area of slope farmland with different slopes has the dynamic process of “decreased→increased→decreased” or “decreased→increased→ decreased→increased”, and the fluctuation degree of >25° slope farmland was the largest. 4) With the evolution of spatio-temporal distribution of slope farmland in the past 35 years, the distribution characteristics of kemel density value in slope farmland have changed, but the change range was small. The distribution of slope farmland in most areas was in low-density value, and the area of high-density value was the smallest. Slope farmland distribution clusters were represented by four significant distribution zones: the Lincang distribution zone, the Lincang-Xishuangbanna distribution zone, the Pu’er distribution zone and the Zhaotong distribution zone. 5) Among the eight types of land use, the landscape dominance of slope farmland was in the middle position, and the fragmentation characteristics of slope farmland were the most significant among all land use types. In the past 35 years, the degree of fragmentation of slope farmland landscape has decreased, and the degree of contiguous use of slope farmland has been strengthened. The research results can provide theoretical support for the rational planning and utilization of sloping farmland and soil and water ecological environment protection in Yunnan. [ABSTRACT FROM AUTHOR]