| A scientific and comprehensive analysis of the current situation and spatial and temporal patterns of change of arable land in Shandong Province is of some significance in exploring the mechanisms of arable land change in China.Firstly,based on the cognitive framework of "elements,functions and values",the study provided a comprehensive overview and detailed analysis of the current situation of farmland resources in Shandong Province from three aspects: farmland elements,farmland functions and farmland values,laying a foundation for the next study on the sustainability of farmland systems.On the basis of a deep understanding of the connotation of "quantity,quality and ecology",the evaluation system for the sustainability of farmland systems in Shandong Province was constructed from three perspectives: the quantity of farmland,the productivity of farmland and the ecological function of farmland,using multi-source data.Finally,the sustainability of the farming system in Shandong Province was analysed based on the theory of system dynamics,and the changes in the sustainability of the farming system from 2021 to 2035 were projected based on a population and economic growth scenario.The details of the study and the main conclusions are as follows.1.Analysis of the current situation of cultivated land elements,mechanisms of functional processes of cultivated land and patterns of changes in the value of cultivated landThis study constructed a multi-factor-based land adaptability evaluation system,and conducts a comprehensive evaluation of the standing and environmental factors of cultivated land in Shandong Province.The results showed that the overall land adaptability of Shandong Province is moderate.The land suitability of northwest and southwest Shandong was relatively good.In this study,Emergy Analysis was introduced to analyse the inputs of economic factors in the production of arable land systems in Shandong Province.The results showed that the factor use efficiency of the cropland system has been increasing year by year,and among the factors,mechanised power has a greater impact on the total output of cropland.The study further assessed the functions of cultivated land in Shandong Province in five aspects: food production,water conservation,soil conservation,carbon sequestration and oxygen release,and habitat maintenance.The results showed that the grain production capacity of the plain areas in northwest Shandong is high.Based on the above research results,this paper proposed an evaluation method for the comprehensive value of arable land based on its economic,social and ecological values,and calculates the comprehensive value of arable land in 2020 using Shandong Province as an example.To address these shortcomings,this paper introduced the dividend discount model in finance and calculates the value of arable land in Shandong Province from 2000 to 2020 based on data such as the value of ecosystem services,GDP growth rate and primary industry GDP.The results showed that the average value of arable land in Shandong province increased from RMB 15,600/mu in 2000 to RMB 61,300/mu in 2020.There is a significant positive correlation between the value of arable land and grain production.2.Analysis of the changes in the amount of cultivated land in the study area and evaluation of the sustainability of the amount of cultivated landA land use transfer matrix was constructed by analysing ESA land use data from 2000 to2020.The results showed that there was a net outflow of 4,192 square kilometres(6,288,000mu)of arable land in Shandong Province over the 20-year period,and that forest land and construction land were the main outflows of arable land in Shandong Province.16 cities in Shandong Province were in a state of net transfer of arable land over the 20-year period.From2000 to 2020,the centre of gravity of arable land in Shandong Province shifted to the northeast,with a distance of about 26 km.The direction of the shift in the centre of gravity of arable land is basically the same as the shift in the centre of gravity of the province’s population and economy.Compared with 2000,the fragmentation of arable land in Shandong Province will be more serious in 2020,and the fragmentation of high-quality arable land will be obvious.The red line for arable land in Shandong Province based on food security was calculated to be 66,000 square kilometres.The data of the "the third surveys" show that the current arable land in Shandong Province is already below this red line,and the sustainability of the amount of arable land in Shandong Province from 2000 to 2020 is generally decreasing,and the protection of arable land is facing challenges.3.Analysis of productivity sustainability of arable land system based on grain yield and non-point source pollution riskOver the past 20 years,grain production in Shandong Province has increased year by year.In spite of the decreasing amount of arable land,the total area of grain sown and grain yields in Shandong Province have both increased significantly compared to 2000.Total mechanised power and compound fertiliser have contributed significantly to the increase in grain yield.As the main grain crop in Shandong province,wheat and maize account for 95%of the province’s total production.The current spatial clustering of functional capacity for grain production in Shandong province is evident in all counties and cities,with Northwest Lu and Southwest shandong being the main grain-growing regions.Grain production capacity in the coastal areas of central shandong and the peninsula is weaker than in 2000.The centre of gravity of grain production has shifted 34 km to the west from 2000.An evaluation of arable land quality based on land adaptation found that.The average quality of arable land in Shandong Province did not change much between 2000 and 2020,and the policy of "balance between occupation and replenishment" has played a role in protecting the quality of arable land.The study also constructed a landscape load ratio index for Shandong’s watersheds based on the "source-sink" theory.The results show that non-point source pollution poses a greater threat to the productivity of cropland in southwest Shandong.4.Calculating the ratio of supply to demand of ecosystem services and evaluating the ecological sustainability of cropland in combination with energy value analysis-related indicatorsIn this paper,the supply and demand ratios for food production,carbon sequestration and oxygen release,water conservation,habitat quality and soil and water conservation were calculated for Shandong Province from 2000 to 2020.The results show that there was high spatial and temporal heterogeneity in the supply and demand ratios of each service.The plains of southwest shandong were a dominant area for many ecosystem services.The Environmental Sustainability Index(ESI),calculated based on the framework of emergy value analysis,shows that the ecological sustainability of arable land in Shandong Province has been decreasing since 2000,reaching a regional low in 2015 and then recently rebounding,but is basically lower than the national average for all indicators in the same year.Among the various crops,soybean has the highest carbon sequestration efficiency and peanut has the highest production factor utilization.Analysis based on the Morphological Pattern Analysis of Space(MSPA)model found that the southwest of Lu has large areas of contiguous arable land and is an important ecological core area.This chapter also uses the MCR minimum resistance surface model to construct the ecological security pattern of the cultivated land system in Shandong Province and delineate the core ecological corridors.5.Constructing a simulation model of the cropland system and predicting future changes in the sustainability of the cropland systemBased on the above framework for sustainability assessment of cropland systems,this paper constructs a system dynamics model for sustainability assessment of cropland systems in Shandong Province with the help of the system dynamics software Vensim.The simulation results for the period 2000-2020 show that the sustainability of farming systems in Shandong Province shows a general fluctuation with a slight increase.The model was further used to simulate the continuity of the cropland system from 2021 to 2035.The simulations are based on five scenarios of future changes in population and GDP growth rates.The simulation results show that the sustainability of arable land in 2035 will range from 1.038 to 1.088,with a higher probability of a decline in sustainability in 2035 compared to 2020,and the task of arable land conservation will remain severe. |
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