Land Use Optimization Under The Perspective Of Restoration Ecology

Land resources are the basis of socio-economic development. Since the reform and opening up, China’s economic development has made great achievements, but also paid a high cost of the ecological environment. At present, China is in an important period of social change and economic transformation, adjustment and rational allocation of land use has increasingly become the urgent task that the great rejuvenation of the Chinese nation and the Chinese dream must face. With the increasing speed of global warming and in-depth of research, the study of land systems become the core of the great challenges of sustainable development humanity is currently facing. As one of the important contents in land change science and land systems scientific research, land use optimization meet directly to the demands of decision-makers, is the necessary choice to achieve sustainable human development.Therefore, this study analyzed the ecological effects of land use change and changes in grain production potential and optimized the land use in Western Jilin Province from the perspective of restoration ecology by rebuilding the historical trajectory of land use change. Concluded that:(1) Large-scale reclamation in western Jilin Province began in the late 19 th century. The land use change trajectories in western Jilin in nearly 100 years can be divided into six phases: the end of the Qing Dynasty(19th century-1911), the Republic of China(1912-1930), the period of Japanese puppet army’s occupation(1931-1945), around the founding of the PRC(1946-1954), the Great Leap Forward and the Cultural Revolution(1955-1977) and since the reform and opening up(1978-2013); the proportion of farmland and grassland in western Jilin in the early days of new China was 1:1, it was 3:1 in 1976 and it up to 5.6:1 in 2013; meanwhile, the alkali-land increased and the marsh seriously declined led to an increasingly disordered land use structure. To further investigate the transforming relationship between various types of land use, this study focoused on the land use change between 1976 and 2013. The results showed that there were 309,200 hm2 of non-arable(mostly were grassland, woodland and marsh) land transformed to arable land. With social and economic development, the expansion of construction land occupied 31,700 hm2 of cultivated land. According Land use transition probability matrix between 2000 and 2013, the land use structure in 2030 was simulated by using system dynamics model and found that ratio of farmland and grassland will become 14: 1. In addition, the land use degree composite index in 2013 reached 239 which had an increase of 4.6 over 1976 and it would reach 247.6 in 2030. Human activity(population density) and climate(temperature and precipitation) change had a significant impact on land use change.(2) The value of ecosystem services in Western Jilin Province was mainly contributed by marsh, farmland, water and grassland.There was a total reduction of 3.93 billion yuan in ecosystem service value of western Jilin between 1976 and 2013; the ecosystem service value of western Jilin detract from 49.198 billion yuan to 46.323 billion yuan in 1976-2000 and it was only 45.268 billion yuan in 2013, mainly due to the conversion of marsh and forest to other land use types, respectively let the total value of ecosystem services lost 3.368 billion yuan and 994 million yuan, of which only the conversion of arable land to marshes make the total value of ecosystem services reduced 2.23 billion yuan. In 2000-2013, the conversion of marshes to other land use types in Western Jilin was the main reason of the reduction in total value of ecosystem services.(3) As an important strategic material related to the livelihood of the people, food security was an important component of national security. Grain production potential could reveal wether arable land pattern was reasonable. Therefore, it was necessary to incorporate the grain production potential into land use optimization. The grain production potentials under different conditions in different years in Western Jilin were calculated by Global Agro Ecological Zone(GAEZ) model. Since 1976, the total grain production potential of western Jilin continues to increase; it increased about 4,516,700 tons between 1976 and 2013; the total grain production potential of western Jilin Province were 11,002,900 tons and 14,056,200 tons in 1976 and 2000; by 2013, the total grain production potential of western Jilin was 15,519,600 tons; the average grain production potential of western Jilin in 1976 were 2346.76 kg/hm2, it increased to 2997.99 kg/hm2 in 2000; the total grain production potential of western Jilin increased by 1,463,400 tons and the average grain production potential of western Jilin increased 312.12 kg/hm2 in 2000-2013; changes in grain production potential was mainly affected by climate, land use and irrigation rates.(4) According to the basic theory of restoration ecology, the structure and patterns of land use in 1976 was selected as the reference system of land use optimation. This study applied a multi-objective programming model and set five scenarios(most ecological, more ecological, ecological-economic, more economic and most economic) in land use structure optimization; “more economic” scenario that mostly developed the grassland animal husbandry became the final choice; the area of farmland, woodland, grassland, water, built-up land, alkali-land, marsh and unused land respectively was 2319.8 thousand hm2, 267.8 thousand hm2, 661.6 thousand hm2, 196.4 thousand hm2, 197.8 thousand hm2, 650.6 thousand hm2, 376 thousand hm2 and 18.5 thousand hm2 after land use optimization. Elevation, slope gradient, slope shape, slope aspect, andform, soil, temperature and precipitation were slected as the biophysics factors affected land use pattern and and population density was slected as the socio-economic factors to simulate space probability distributions of each type of land use in 2030.(5) Optimization allocation of land use spatial structure was processed under different climate scenarios and irrigation levels by using multi-criteria evaluation model and combining the status quo of land use, climate change and future grain production potential, followed five principles(There were two key steps: firstly, Western Jilin was divided into a number of grids with a size of 1000 m × 1000 m; secondly, the area percent of each type of land use within each grid was calculated). After optimization, the proportion of farmland and grassland in western Jilin reached 3.5:1 and the spatial structure of land use was more reasonable, but also the total value of ecosystem services and the grain production potential of western Jilin increased, illustrating the results of land use optimization was scientific and reasonable and feasible.