| Since the implementation of the western development policy,the economic and social development of Guanzhong-Tianshui Economic Zone has been developing rapidly.With the growth of economy and population,people’s demand for grain production is increasing,ecological areas are encroached on,soil erosion is serious,and carbon emissions are increasing sharply.The implementation of the economic development policy has brought damage to the ecological environment of the study area,and the implementation of grain for green program has erected an ecological protection barrier for us.It is undoubtedly an important content to study the interaction between the spatial distribution of land use and ecosystem services,and between different ecosystem services under the background of grain for green program.Therefore,this paper takes Guanzhong-Tianshui Economic Zone as the research area,quantitatively simulates regional food production services,carbon sequestration services and soil conservation services,analyses the impact mechanism of topography,climate and social demographic factors on the three ecosystem services under the background of grain for green program,and reveals the trade-offs and synergies among different ecosystem services and the efficiency of ecosystem services with different objectives.Based on above all,the optimization strategy of spatial pattern of regional ecosystem services is given,which provides an intuitive scientific reference for the management of emerging land competition in other regions and environment.The main contents of this study include:(1)calculating the ecosystem services of grain production,carbon sequestration and soil conservation in Guanzhong-Tianshui Economic Zone in 2015,and analyzing the spatial distribution characteristics of the three ecosystem services;(2)establishing ecosystem services network model based on Bayesian network and ecological process to determine the trade-off or synergy between grain production,carbon sequestration and soil conservation;(3)setting up land use scenarios under the background of grain for green program,calculating the probability distribution of three ecosystem services under each scenario based on Bayesian network;(4)according to the trade-off and synergy between ecosystem services,and the ecosystem services demand of stakeholders,the spatial pattern optimization strategies under different target ecosystem service efficiency in the study area were given.The main conclusions drawn from the study are as follows:(1)Spatial differences exist in the distribution of ecosystem services in Guanzhong-Tianshui Economic Zone.In the whole year of 2015,the total grain production of Guanzhong-Tianshui Economic Zone was 9.42×106t,with an average grain production of 1.18 t/ha.The total grain production of Weinan City was the highest,especially Fuping County,Pucheng County and Linwei District.As far as carbon sequestration capacity was concerned,Baoji City was the strongest,Tongchuan City and Yangling District were the weakest.Among the counties in the study area,Fengxian,Taibai,Weibin,Tianshui,Maiji and Longxian have the strongest carbon sequestration capacity,with the carbon sequestration per unit area exceeding 50 t/ha.In 2015,the total soil conservation capacity of Guanzhong-Tianshui Economic Zone was 2.36×109t,and that of Baoji City was the strongest,with the total soil conservation capacity reaching 8.16×108t and the average soil conservation per unit area reaching 450.74 t/ha.(2)The correlations between ecosystem services and bio-environmental factors and between ecosystem services are different.Grain production has a high correlation with slope,land use,vegetation cover and soil erodibility;carbon sequestration has a strong positive correlation with NDVI,NPP,soil respiration,soil organic carbon,and a strong negative correlation with soil and water conservation measures;soil conservation has a relatively strong correlation with slope,NDVI,rainfall,soil and water conservation measures and rainfall erosion.Grain production and carbon sequestration,grain production and soil conservation are trade-offs,while carbon sequestration and soil conservation are synergistic.(3)The implementation of grain for green program is of great significance to the improvement of carbon sequestration and soil conservation services in ecosystems,but it also weakens food production services.The maximum expected value of grain production service was 2.085696,which was lower than the expected value of grain production in 2015,and the minimum expected value of carbon sequestration service was 2.728526,which was higher than the expected value of carbon sequestration service in 2015.The expected value of soil conservation in 2015 was between the highest and lowest values in all scenarios.Under the scenario of maximum expected value of food production service,no matter in population reduction area,population stabilization area or population growth area,the cultivated land type remains unchanged where the slope is lower than 25 degrees.Where the slope is greater than 25 degrees,the cultivated land type in population growth area is converted to grassland,and the fallow land is converted to woodland in population reduction area and stability area.This scenario provides a reference for the conversion of fallow land use types to meet the needs of social grain production under the background of the grain for green program.Under the scenario of maximum expectation of carbon sequestration service and soil conservation service,no matter how the population changes and the slope districts are distributed,all fallow land is converted to woodland.The conversion scheme of fallow land use type in this scenario provides a reference for the priority development of carbon sequestration service and soil conservation service under the background of the grain for green program.the conversion scheme provides a reference;under the scenario of maximum expectation of carbon sequestration service and soil conservation service,no matter how the population changes and the gradient districts are distributed,al]fallow land is converted to forest land,and the conversion scheme of fallow land use type in this scenario is carbon sequestration service and soil conservation service under the background of returning farmland to forestry.The priority development of business provides a reference.(4)Considering the single ecosystem service efficiency only,the optimum areas for grain production are mainly distributed in Shangluo City in the southeastern part of the study area,Yangling District in the central part and Zhouzhi City,Huxian and Chang’an districts in the southern part of Xi’an City,Fengxian and Meixian districts in Baoji City;the optimal areas for carbon sequestration are mainly distributed in Xunyi County,Weibin District of Baoji City,Southern part of Chencang District,Qinzhou City of Tianshui City.the optimal soil conservation areas are mainly located at the northern foot of Qinling Mountains in the southern part of the study area,such as Fengxian and Taibai Counties in Baoji City,Zhouzhi County and Huxian County in Xi’an City,as well as some areas of Chang’an District and Zhashui County in Shangluo City.Considering the efficiency of dual-objective ecosystem services,the optimal land use allocation scenarios corresponding to any point on the dual-objective efficiency curves of grain production and carbon sequestration services,grain production and soil conservation services are all the scenarios that take into account both the efficiency and trade-off of dual-objective ecosystem services.The optimal land use allocation scenario between carbon sequestration and soil conservation is Ls9Ms9Hs9,which is the best scenario for land use allocation between carbon sequestration and under the scenario,both the carbon sequestration expectation and the soil conservation expectation reached the maximum.The trade-off and efficiency analysis of multi-objective ecosystem service shows that the highest overall benefit of grain production,soil conservation and carbon sequestration services corresponds to Ls9Ms9Hs9,and the scenario of balanced development among the three ecosystem services is Ls2Ms9Hs2.The main features of this paper are as follows:(1)729 land use scenarios were constructed,which fully considered the impact of human activities such as population distribution change rate and the implementation of grain for green program on the ecosystem services simulation and relationships between services.(2)It provides an open Bayesian network framework for ecosystem services,starting from single-objective,double-objective and multi-objective ecosystem service efficiency,we quantify the ecosystem service efficiency of different objectives and optimize the ecosystem service in an all-round way. |
PDF Full Text Request