Quantification Of Tradeoffs On Forest Ecosystem Services In Mount Funiu Region

As an important part of terrestrial ecosystems,forest ecosystems provide multiple ecosystem services for human society,and these ecosystem services interact with each other,showing tradeoffs and benefit synergies.Scientific understanding of ecosystem services tradeoff or synergy and their spatial differences will be not only conducive to improve the overall benefits of regional ecosystem services,but also contributed to scientific management and protection of forest ecosystems.Based on the multi-source data such as forest map,topography,NDVI,meteorology and soil,the key forest ecosystem services including forest volume,carbon storage,water yield,soil retention and habitat quality in the Mount Funiu Region were evaluated and mapped through integrated use of CASA model,InVEST3.2 model and Arc GIS10.2 software.Further,characteristics of interactions among different ecosystem services and the overall benefits were mapped and discussed from multiple spatial scales(i.e.,region,forest type,county,vertical belt)by spatial overlay analysis method,correlation analysis method and standard deviation method,while the partitioning scheme for forest resource management was proposed by using K-Means clustering analysis method.Finally the relationships between ecosystem services and natural factors or socio-economic factors were discussed,and the mechanism underlying the tradeoff relationship between ecosystem services was quantified by using the geodetector method.The main results and conclusions are as follows:(1)The spatial variation of forest ecosystem services is quite notable in Mount Funiu Region.The high value areas of forest volume,carbon storage and habitat quality are mainly located in the middle-and highaltitude mountains,and the water yield service decreases from south to north,while the high value areas of soil retention are located at the junction of counties in the eastern of study area.As far as forest type scale is concerned,except for the water yield service,the other service units provided by natural forests are all higher than the plantation forests.As far as county scale is concerned,except for the water yield service,the other service units in Zhenping and Neixiang are all relatively low.As far as vertical belt scale is concerned,since the natural environment conditions of the south slope are superior to those of the north slope,the water yield and soil retention service supply capacity provided by each vertical belt in the south slope is stronger than that in north slope,but the remaining services still remain to improve.(2)On regional scale,the area proportion of forests with low-synergy and different degrees of tradeoffs between services is 71.21%,and 28.79% of forests show high synergies.On forest type scale,the highsynergy areas of natural broad-leaved forests such as broad mixed forest,Quercus aliena var.acuteserrata forest and Quercus glandulifera var.brevipetiolata forest account for a large proportion,while the coniferous forests including Pinus massoniana,Pinus tabulaeformis and Pinus armandi are dominated by a single service.On county scale,the high-synergy areas in the five counties(i.e.,Lushan,Xixia,Nanzhao,Neixiang,Zhenping)account for a relatively large proportion,but most areas are dominated by water yield service.On vertical belt scale,the best synergy is in the middle-mountain deciduous broad-leaf forest belt on the south slope(SIII),and the worst synergy is in the low-mountain deciduous broad-leaved forest belt on the north slope(NI).(3)The overall benefits of the high-mountain areas are higher than those in the low-mountain areas,and the overall benefits of natural forests are higher than those of plantation forests.However,the overall benefits are still relatively low,and the uneven distribution of benefits among ecosystem services is more prominent.On forest type scale,the overall benefit of Quercus glandulifera var.brevipetiolata forest is higher,and the benefit distribution is relatively balanced.On county scale,the status of forest resources in Luanchuan is closer to the ultimate goal of forest resource management.On vertical belt scale,the SIII with the highest overall benefit and balanced distribution of benefits,is the optimal state of coordinated development of forest ecosystem services.(4)Quantitative results of service tradeoffs indicate that the low level of soil retention service at the regional scale is the main reason for the high tradeoff in most regions.In the future,increasing soil retention capacity should be the most important thing in the ecosystem service management.On forest type scale,the synergistic gain relationship between broad-leaved forest ecosystem services is more common,while the synergistic weakening and the high-tradeoff relationships between coniferous forest ecosystem services are more common.On county scale,there is a state of low tradeoff and high service benefit value between the water yield and carbon storage services in Lushan,Nanzhao,Xixia,Neixiang and Zhenping.On vertical belt scale,there is a state of the lowest tradeoff and highest service benefit value between the water yield and carbon storage services in the SI(i.e.low-mountain deciduous broad-leaved forest belt on the south slope)and SII(i.e.deciduous broad-leaf forest belt containing evergreen tree species),and there is a state of lower tradeoff and higher service benefit value between forest volume and water yield,soil retention in SIII.(5)The forest management sub-district based on the township scale is more suitable for the actual situation of the study area.Poor water supply services in most areas of the north slope are the main reasons for the tradeoffs between services.Engineering measures should be taken to improve water resources restrictions in light of local climate background and site conditions.The overall benefits of ecosystem services in the middle and low mountains and foothill areas in southeast of the study area are relatively poor.Thus in the future,it is necessary to strengthen the management of plantations and secondary forests on the south slope,reduce or prohibit the destruction of human activities,and increase cultivation of coniferous and broad-leaved mixed forests instead of pure forests.On the other hand,it is necessary to increase cultivation of Quercus aliena var.acuteserrata forest and Quercus glandulifera var.brevipetiolata forest on the south slope to improve the overall service capacity of the south slope,and in order to better develop the ecosystem services potential of the site conditions of south slope.(6)The contribution ratio of natural environment factors to the tradeoff relationship between ecosystem services is higher than that of socio-economic factors.Particularly the contribution ratios of forest type,precipitation and altitude are generally higher.Specifically,from high-altitude area to low-altitude area,the forest type has changed significantly,coupled with the increase of the destruction degree of forest resources by human disturbance and the increase of secondary forest and plantation area,the ecosystem services such as the forest volume and carbon storage are reduced,while the increase in precipitation leads to an increase in water yield capacity,so the tradeoff relationship is more common.In the future,the protection of natural forests and the improvement of the quality of plantations should be strengthened,and engineering measures also should be taken to improve the water resources restriction in high-altitude areas and the north slope,which will help to alleviate the tradeoff relationship between services.The impact of socio-economic factors is relatively weak because of the complexity of their impacts,especially after the population density and economic density reach the highest value,the ecosystem services such as the forest volume and carbon storage have increased again,which may be caused by the differences in the composition of local industrial structures.Therefore,in the future,developing emerging industries and promoting the upgrading of regional industrial structure will help to alleviate the tradeoff relationship between forest ecological benefits and economic benefits.