Multi-scenario Prediction And Degradation Risk Assessment Of Ecosystem Services Based On Land Use Change

Ecosystem services(ESs)refer to the multiple benefits people obtain from ecosystems and are seen as the basis for human survival and development.Drastic land use changes have significantly altered the structure and function of ecosystems and threatened the supply of ESs.Therefore,exploring the process of regional LULC and its impact on ESs is crucial to territorial spatial governance and ecological civilization construction.Since 1978,China has made remarkable progress in socio-economic and land development through reform and opening up,which has led to great satisfaction in people’s life.However,high-intensity human activities,especially rapid and disorderly LULC,have caused serious disturbances to the natural environment,triggering structural damage and functional disruption of ecosystems.A series of growing ecological problems,such as water shortage,soil pollution,soil erosion,desertification,and biodiversity loss,have greatly jeopardized regional ecological security.Given the serious situation,China has made a major strategy to achieve ecological civilization to achieve the harmonious development between human beings and nature.To promote the modernization of territorial spatial governance,it is necessary to address the major issues of optimizing the landscape pattern and enhancing the sustainability of ecosystems.An urban agglomeration is a geographic area with high population concentration,rapid economic development,and prominent land use conflicts.The Wuhan metropolitan area(WMA)is located in the geographical center of China and consists of nine major cities,where hundreds of mountains and numerous rivers and lakes form a particularly distinctive and complex ecosystem.Benefiting from the favorable natural conditions and transportation network,the WMA has played a crucial role in China’s modernization.In the last two decades,this region has become one of the fastestgrowing and largest metropolitan areas in China.However,the growth process has not been entirely positive as environmental pollution and ecological degradation have also risen.For example,the continuous expansion of built-up areas has encroached on the surrounding natural and high-quality arable lands,creating habitat fragmentation and a decline in biodiversity.Therefore,based on the theories of man-land relationship,landscape sustainability,and risk management,this work systematically carries out the research on multi-scenario prediction and degradation risk assessment of ESs based on land use change in the WMA.Specifically,we first assessed and analyzed the spatiotemporal evolution characteristics of land use patterns and ESs(including agriculture production(AP),carbon sequestration(CS),soil conservation(SC),and water retention(WR))in the WMA in 2000,2010 and 2020.Meanwhile,the regional land use pattern in 2030 was simulated under five typical scenarios of historical continuity(HC),sustainability(SD),economic development(ED),ecological protection(EP),and food security(FS).ESs in 2030 and the degradation risk of future ESs were then predicted based on future land use change.On this basis,zonal regulation strategies for the degradation risk of ESs are also proposed in a targeted manner.The main finding of this study are as follows:(1)The characteristics of land use changes in WMA are systematically analyzed from multiple dimensions of the quantitative structure,spatial configuration,and development intensity.We found that the land use structure of the study area has been relatively stable in the past two decades,with cultivated land and woodland being the dominant land use types.The changes in land use structure are mainly characterized by a significant reduction in cultivated land,grassland,and unused land and a continuous increase in woodland and construction land.Large areas of lost cultivated land are the main source of other new lands.At the same time,the regional landscape pattern shows an obvious trend of increasing diversity,fragmentation,and complexity.On the one hand,urban expansion has exacerbated the reduction and fragmentation of cultivated land.On the other hand,the patterns of woodland and waterbody have been effectively optimized under the influence of environmental protection measures,improving the local ecological environment.In addition,with the rapid socio-economic development,the regional land development intensity has continued to increase and has shown significant regional differences in the past two decades.(2)The CLUMondo model was used to predict land use patterns in 2030 in the WMA.The results show that there were significant differences in land use structures under different future scenarios.The area of cultivated land increases most significantly in the HC scenario.Woodland conservation works best under the EP and SD scenarios.Built-up land is expected to grow rapidly under the HC and ED scenarios.Grasslands and unused lands show declines in all scenarios,while waterbody increases slightly only in the EP scenario.The landscape pattern of the WMA will change significantly in the next decade,showing the trend of simplification of landscape patterns(i.e.,the decline in landscape diversity and patch complexity).The land development intensity in the WMA is expected to increase significantly under all scenarios except the EP scenario.In addition,the validation results show that the CLUMondo model has high applicability in the land use simulation in this work.(3)Four typical ESs in the WMA and their spatiotemporal changes were assessed and analyzed from 2000 to 2020.It was found that the regional AP has increased significantly with a clear trend of a gradual slowdown,while CS,SC,and WR show a trend of growth followed by a decline.The WR showed a significant increase in 2010 due to extreme rainfall.Spatially,AP is roughly characterized by higher in the central and western regions and lower in the southeast and northeast.The regions where AP increased significantly were mainly concentrated in the northern part of the WMA,such as Qianjiang and Xiantao.Meanwhile,CS,SC,and WR generally vary with topography and are relatively low in the Jianghan Plain and the middle and lower reaches of the Yangtze River Plain,and relatively high in the low mountainous areas of the northeast and southeast.In addition,the trade-offs between AP and CS,SC,and WR are significant,implying that an increase in agricultural production will result in a loss of the other ESs.These relationships were found to be mainly distributed and form clusters in the west-central southeastern parts of the study area.The synergistic relationship between CS,SC,and WR is predominant,indicating that the three services are mutually beneficial and reinforcing to each other.(4)A Bayesian Belief Network(BNN)is constructed to predict the future ESs at the catchment scale based on the mechanism of the impact of land use change on ESs.The BNN in this work is found to be effective in integrating observational data and expert experience to make multi-scenario projections of ESs states in WMA.We found that the probability of lower and medium levels for AP and CS is higher than that of higher and highest levels,while the opposite is the case for SC and WR.At the same time,different scenarios have different effects on the probability distribution of ESs states.For example,the average probability of a higher level of AP under the FD scenario is 0.8 percent higher than that of the HC scenario.This finding suggests that land use changes under the FS scenario would be more likely to enhance the overall level of regional AP.In sum,AP benefits most from the FS scenario,while other services benefit more from the EP scenario and the SD scenario.In general,the SD scenario is most beneficial for maximizing the protection effects of multiple ESs.(5)An assessment framework was constructed by integrating the potential loss of ESs and the uncertainty of future land use changes to measure the degradation risk of ESs at the catchment scale in the WMA.The results show that 299 catchments are at a degradation risk of AP,of which 65% belong to moderate or above.There are 216 units with degradation risk for CS,of which 66% are at moderate risk or above.SC has 226 units with degradation risk,but only 46% of them are moderate or above.The degradation risk of WR is 311 units and 63% of them are above moderate risk.Ecological risks are generally low under EP and SD scenarios but higher under FS and ED scenarios.According to the risk status,the WMA can be divided into four major risk areas: Ⅰ.The region Ⅰ with low risk of all ESs,which is distributed in a discontinuous strip along the line of Xiaogan North-Huangshi South;Ⅱ.The region Ⅱwith high degradation risk of CS,SC,and WR,which is distributed in clusters in the eastern part of Huanggang and the southern part of Xianning;Ⅲ.The region Ⅲ with mainly degradation risk of AP,which is mainly distributed in the triangle of EzhouQianjiang-Xianning;and Ⅳ.The region Ⅳ with a high risk of AP,CS,and WR.The overall pattern of these areas is relatively fragmented,and the contiguous area is mainly located in the northwest of Xianning and the east of Huangshi.(6)Given the uncertainty and heterogeneity of ecological risk,a risk management framework is constructed in this study.The specific strategies are then proposed in the context of the risk status,natural ecological background,and socio-economic background of the WMA.First,we should develop a scientific multidimensional target system based on regional reality.Second,we should focus on improving the regional risk management environment and operation mechanism.Third,the planning should be strengthened to guide the implementation of relevant management measures.Finally,new technological tools should be fully applied to develop risk management approaches and capabilities.For different regions,region Ⅰ should deeply optimize the regional landscape structure and enhance ecosystem stability and productivity to create an urban ecological barrier.Region II should continue to promote forest ecosystem restoration under the principles of moderate development,protection first and conservation combined.Region III needs to enhance the production function of cultivated land by developing ecological agriculture.Region Ⅳ should strengthen the multiple-dimensional protection of the composite ecosystem and enhance the ecosystem function to achieve the goal of the ecological demonstration area.The main innovations of this work are as follows.Using CLUMondo and BNNs model to construct a research framework for simulating the response of ESs to land use change and effectively assessing the future response of ESs in the WMA under typical scenarios.On this basis,a future-oriented risk assessment system is further constructed by coupling the dynamic changes of ESs and the uncertainties of land use change,which effectively identifies the degradation risk of regional ESs.