| The multifunctionality makes landscape rich in goods and services for human development.Enhancing the landscape multifunctionality(LM)is an effective pathway to realize the regional ecological restoration and the sustainable development.As a spatial unit linking the important food production area and the ecological security barrier area,the upper East Liaohe River Basin(UELRB)has the important task of maintaining regional food security and ecological security.However,due to overexploitation of ecological space,the UELRB has experienced ecological problems such as water scarcity,soil erosion,and declining value of ecosystem services,leading to an urgent need for restoring the regional LM.This study comprehensively assessed the spatiotemporal evolution of the landscape and its multifunctionality in the UELRB between 1990 and 2020.In addition,to project the potential benefits and limitations of existing territorial spatial planning,this study simulated the spatiotemporal evolution of the landscape and its multiple functions in the UELRB between 2025 and 2050,which provides a scientific basis for implementing and improving ecological restoration efforts.The main findings of this study are briefly listed below.(1)To clarify the key factors that constrain the regional sustainable development,this study summarized the driving mechanisms of the landscape evolution of UELRB between 1990 and 2020.The landscape evolution process can be divided into three periods by 10-year intervals,including ecological space overload period(1990～2000),landscape management transition period(2000～2005),and ecological restoration period(2005～2010).During the ecological space overload period,the forest landscape lost significantly(-4.45×104 ha)and the dryland landscape expanded significantly(+1.36×104 ha).During the landscape management transition period,the forest landscape lost slightly(-0.35×104 ha)and the dryland landscape reduced continually(-2.29×104 ha).During the ecological restoration period,the forest landscape recovered significantly(+2.19×104 ha)and the dryland landscape reduced continually(-2.29×104 ha).Territorial restoration projects and socioeconomic policies were the driving force behind the transformation from the overload development period to the ecological restoration period,resulting in the influence of human factors(e.g.,riparian restoration,road construction)on landscape change overtaking natural factors(e.g.,temperature,precipitation,topography).Thus,human activities become the key factor limiting the ecological restoration in UELRB.(2)This study simulated the spatiotemporal evolution of four key landscape functions(i.e.,vegetation water production,food production,vegetation carbon sequestration,and habitat maintenance)between 1990 and 2020.Results confirm the UELRB has ecological problems with degraded water production and habitat maintenance functions.From 1990 to 2020,the water production per unit area decreased significantly in forest landscapes(-69.74 m3),followed by dryland(-60.41 m3).The average habitat quality in forested landscapes decreased the most(-0.22),followed by paddy landscapes(-0.09).In contrast,the regional food production function continued to increase,with grain yields per unit area increasing by 2.73 t/ha and 1.67 t/ha in paddy and dryland landscapes,respectively.The carbon sequestration per unit area decreased by 125.68 × 104 gC/ha and 29.12 × 104 gC/ha in forest and grassland,respectively;meanwhile,the carbon sequestration per unit area increased by 46.44 × 104 gC/ha and 18.04 × 104 gC/ha in paddy and dryland landscapes,respectively.Because investigated functions weakened significantly in forest landscapes,it could be confirmed the necessity and importance of forest restoration,which is the main restoration aim of relevant territorial spatial planning.(3)This study used multifunctionality indicator and synergy indicator to spatially express the strength of LM and synergy relationships of multiple landscape functions.Results show that the forest multifunctionality weakened significantly between 1990 and 2020 because of the continuous decline in multifunctional synergy,showing that the simple restoration of forest area could not enhance the synergistic relationship of multiple landscape functions.In contrast,thanks to the increasing multifunctional synergy,paddy fields surpassed forest and have been becoming the most multifunctional landscape type,with the strongest integrated ecological benefits since 2000.However,the multifunctional indicator for paddy fields in 2020(3.37)was still lower than for forest landscapes in 1990(4.36).Therefore,the existing territorial spatial restoration strategy should seek an effective pathway to increase the spatial concentration of high-quality landscape functions.(4)This study projected the change of landscape and its four functions between 2025 and 2050 under six scenarios.It has been confirmed that the forest cover of UELRB could restore to 22%in 2035,which is the target of the existing territorial spatial planning.Also,UELRB is expected to increase the forest cover to 32.32%by 2050 with the support of existing territorial spatial restoration projects.However,the restoration process will be affected by future climate change,and the rate of forest landscape restoration will slow down when the temperature increases and precipitation decreases(i.e.,forest cover will decrease to 20.64～21.44%in 2035).Thus,it is recommended to control the regional carbon emissions to reduce the negative effect of climate change on regional ecological restorations.(5)This study simulated the spatiotemporal evolution of four landscape functions(i.e.,vegetation water production,food production,vegetation carbon sequestration,and habitat maintenance)between 2025 and 2050.Results show that with the massive increase of forest landscape area,the total carbon sequestration of regional vegetation will significantly increase,reaching 4.51 TgC in 2050,which will support the achievement of regional goals of carbon neutrality and emission peak.The regional habitat maintenance function will also improve by 17.11～22.69%.However,the UELRB is projected to experience a decrease in total vegetation water production(-2.03 × 108 m3)and total food production(-279.68 × 104 t)because of the replacement of the arable landscape by forest restoration.The falloff of these two functions will aggravate the regional water shortage and threaten the regional food security.Relevant practitioners should further strengthen the synergistic management of landscape functions and the technological upgrading of agricultural production. |
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