Quantitive modeling changes in area of reclamation and returning cultivated land to forest or pastures under representative concentration pathways (RCPs) climate scenarios

Abstract: Northeast China as one of the important agricultural production bases is an area under reclamation and returning cultivated land to forests or pastures. Therefore, it is of great practical significance in guaranteeing the sustainable development and national food security to study the spatial and temporal variation of cultivated land in Northeast China under future climate scenarios. With the Northeast China as the study area, the authors collected data of land use, natural environment and social-economic, and simulated the spatial distribution and changing trends of cultivated land with the land use change dynamic (DLS) model based on the scenarios of land use planning and representative concentration pathways (RCPs) from year 2010 to 2030. The results showed that the area of cultivated land had an overall decreasing trend under the land use planning scenario, but the area of upland field increased slightly from year 2000 to 2010 and then declined greatly, while the paddy field continuously declined from year 2000 to 2030. The major land use type converted from the cultivated land was forest which mainly located in the Great and Small Xing'an Mountain and Changbai Mountain. Cultivated land transferred to residential area is around the original city. However, the expansion of urban area is not obvious due to the dispersion of conversion area over a large studied area. The increase in the area of cultivated land was mainly in the northern and western parts of Northeast China. Besides, the total area of cultivated land had a tendency to increase considerably under the Asia-Pacific Integrated model (AIM) scenario, with the upland field expanding more obviously and the paddy field declining slightly, which was mainly transferred from forest and grassland. Among them, the converted forest land was in the Greater Xing'an Mountains, while the converted grassland was near the Three River Plain and Songnen Plain. In addition, the cultivated land showed a greater decreasing trend under the model for energy supply strategy alternatives and their general environmental impact (MESSAGE) scenario compared to the land use planning scenario, and most of them were from grassland and residential area. Although the cultivated land showed a downward trend both in MESSAGE and land use planning scenarios, the direction of change was different. MESSAGE scenario had a rapid economic development and more emissions of greenhouse gases?, so the expansion of residential area was also one of the significant reasons for decrease in cultivated land, while the planning scenario focused on the ecological construction, therefore, more cultivated land was converted to forest. As for the AIM scenario, it had a similar economic development ratio, but it emphasized the agricultural production, and ecological construction was less than that under the planning scenario. Moreover, analysis on the conversion between different land use types indicated that the reclamation and returning cultivated land to forests or pastures was likely to continue under future scenarios, but the frequency of occurrence could decrease as the time goes by. The conclusions can provide significant decision-making information for the rational agricultural planning and cultivated land protection in Northeast China to adapt to the climate change.