Changes of land pressure and land use mode in Loess hilly gully region

Abstract: The development of human society has brought great pressure on land resources, while the reasonable land use pattern is the key to alleviate the pressure and realize the regional sustainable development strategy. This paper, based on the land demand of social, economic, and ecologically sustainable development, constructs a quantitative evaluation method of land pressure from three aspects of food production, economic development, and ecological protection. According to the survey data of the Shanghuang experimental area in different periods, this paper analyses the changes process of land pressure index and land use patterns in different periods, the results show the following: the land pressure index was 0.738 before comprehensive control of soil and water erosion, which is severe pressure level; the comprehensive pressure index of land fell to 0.247 in year 2000; the land pressure decreased significantly; the pressure level demonstrates a mild pressure rating; and, during the conversion of cropland to forest and grassland, the land pressure index continued to decline, which reached 0.164 in year 2010. Land pressure was defined as land use pattern interactions throughout the whole study period, but the interactional features are significant differences in different periods. Before 1982, under the conditions of the traditional agriculture production pattern, due to the low levels of agricultural productivity and the rapid population growth, the land resource was facing tremendous pressure. The characteristics of land use pattern were that the productivity development level and the population growth were extremely imbalanced, the resources utilization and protection were in serious disorder, and the man-land relationship was opposite. During the periods of governance and returning farmland to forest and grassland, the land resource was facing greater pressure because of the situation of population growth. Under the interventions of technical factors and policy factors, the level of agricultural productivity increased greatly, so the land use pattern was changed from the extensive to the intensive management, the grain yield and economic income had great improvement, the ecological construction obtained great achievements, ecology and economics presented a harmonious development situation, the sustainable utilization level of land resource continuously improved. From the mutual relationship of land use pattern and land pressure, population growth is the primary source of land pressure, while the productivity level is the key to relieve the pressure.