Distribution of Irrigated and Rainfed Agricultural Land in a Semi-Arid Sandy Area

Under water resource and terrain constraints, a certain scale threshold of irrigated and rainfed agricultural areas exists in semi-arid sandy areas. If this threshold is exceeded, water and soil resources will be unbalanced, and the ecological environment will deteriorate. Accurate assessment of the suitable scale of cultivated land in semi-arid sandy areas is of great significance for sustainable utilization of cultivated land resources and regional ecological security. Most existing research methods are based on water resource constraints and rarely consider terrain factors. Therefore, based on the principle of water balance and with the Horqin Left Wing Rear Banner as the research area, this study adopted a multi-objective fuzzy optimization model and relative terrain index analysis method to explore the appropriate spatial ratio of irrigation and rainfed agriculture. The results show that the area of irrigated agriculture in the study area is 77,700 hm2, and the appropriate scale is 91,700 hm2. The current area of dry farming is 184,600 hm2, and the suitable scale is 117,100 hm2. The results also show that the utilization efficiency of water and soil resources in irrigated agriculture was not optimal, rainfed agriculture exceeded its suitable scale, and water and soil resources were seriously unbalanced. However, the region of cultivated land that exceeds the appropriate scale is mostly located in an area with poor terrain, less precipitation, and other unsuitable conditions for cultivation, which is prone to abandonment, resulting in deterioration of the ecological environment. Therefore, the spatial layout of agricultural land use in the study area should be adapted to local conditions, and the water-saving structure of irrigated agriculture should be optimized to achieve the maximum comprehensive benefits. Dry farming should be controlled on a reasonable scale, and the part exceeding the appropriate scale should be returned to grassland to ensure sustainable development

Landscape ecological risk assessment of the Hailar River basin based on ecosystem services in China

The study aims to clarify the temporal and spatial evolution characteristics of landscape ecological risk in Hailar River basin in recent 30 years, and to serve for scientific formulation of ecological management strategies. In the study, ecosystem services were used to improve the traditional landscape ecological risk assessment method, and the theoretical basis of landscape ecological risk was clarified using the human-nature system method. The results show that, on the spatial scale, the overall landscape ecological risk of Hailar River basin is characterized by high in the middle and low around. The high-risk areas are mainly located in the transition zone of “urban-grassland” and “urban-forest” in the middle of the basin and the main mining areas, which are distributed in strips along the main roads and rivers. Low risk areas are mainly distributed in the Great Khingan Mountains forest area in the east and north of the basin. In terms of time scale, the landscape ecological risk in the edge of the watershed has always maintained a high proportion of low-risk areas (75.35 %), while the area of high-risk areas in the middle of the watershed has experienced a process of first increasing and then decreasing. In terms of ecological governance, high-risk areas should achieve orderly urban construction and orderly development of mineral resources, and establish a classified management system of natural resources. Low risk areas should continue to promote measures to prohibit logging and limit grazing, and establish a supporting ecological compensation mechanism. The conclusion shows that urbanization, mineral development and management, and the implementation of forest and grass policies are the main driving factors for the change of landscape ecological risks in Hailar River basin. The basic principles of zoning control and human land coordination should be adhered to, and the size of cities and towns should be adjusted reasonably to promote the orderly development of mineral resources and the orderly construction of projects