Greenspace Ecosystem Services And Landscape Planning Implications In Mountainous Cities

Mountainous cities are key areas for the new-type urbanization and ecological civilization construction in China.While achieving great socioeconomic development,mountainous cities are threatened by severe environmental problems(e.g.,biodiversity loss,soil erosion,and water pollution)due to population growth,built-up area sprawl,and greenspace fragmentation,along with rapid urbanization.Research on ecosystem services in mountainous cities is inevitable to promote greenspace patterns,improve human settlement quality,and achieve local sustainability.However,little is understood about the spatial patterns,tradeoff and synergy relationships,and response rules to landscape patterns of ecosystem services in mountainous cities.Following the classical urban ecology study framework(patterns,impacts,and promotion),this research took Chongqing metropolitan area—the most famous mountainous city in china,which has diverse landscapes and urbanization gradients,as an example,to study greenspace ecosystem services and landscape planning implications in mountainous cities.The objectives of this dissertation were to(1)quantify the spatial patterns of ecosystem services;(2)investigate the coupling relationships between ecosystem services and landscape patterns;(3)explore landscape planning strategies and methods for improving ecosystem services in mountainous cities.In this research,I used landscape metrics to quantify the landscape patterns in Chongqing metropolitan area and found the optimal scale for landscape analysis.Then the local critical ecosystem services were explored based on greenspace plans explanations and residents’ preference survey.Next,I quantified the patterns of ecosystem services and the trade-offs between ecosystem services at multi scales with multidisciplinary approaches and mass data.Afterward,the major impacting indicators and impacting rules of ecosystem services heterogeneities were detected by Geodetector.Lastly,I proposed a greenspace planning framework of coupling landscape patterns and ecosystem services with the above findings.Major findings are summarized as follow:(1)The four mountains(Mount Jinyun,Mount Zhongliang,Mount Tongluo,and Mount Mingyue)and two rivers(the Yangtze River and Jialing River)contributed to the excellent frame of greenspace in the Chongqing metropolitan area.However,greenspace in the study area kept decreasing and fragmenting at the expense of urbanization in the past 30 years.The characteristics of landscape patterns were affected by topography,rivers,mountains,and urbanization.Greenspace in the mountains was retained,but greenspace in the waterfront areas was developed for urbanization and agriculture.(2)Local critical ecosystem services(habitat,food production,water retention,water purification,soil retention,carbon storage,heat island mitigation,and recreation)were identified based on local key environmental problems,greenspace plans,and residents’ preferences survey.(3)The spatial patterns of ecosystem services in the Chongqing metropolitan area were significantly affected by the macro landform pattern of “four mountains,two rivers,and three valleys.” In terms of service efficiency ratio between the most significant hotspots and no significant spots areas,the spatial heterogeneities of heat island mitigation and recreation were the highest;followed by forest bird and waterfowl habitat,food production,nitrogen retention,phosphorus retention,and soil retention;the spatial heterogeneities of water retention and carbon storage were relatively weaker.(4)The tradeoffs and synergies between ecosystem services in Chongqing metropolitan area were complex and changed across scales.The synergies between food production and nitrogen or phosphorus retention,impacted by the landscape mosaic consisting of cultivated areas and forests,were different from other studies.As the scale increased,the relationships between most ecosystem services remained unchanged with stronger relevance,presumably because the heterogeneity of landscape patterns and natural geographical conditions reduced.A few tradeoffs or synergies between ecosystem services transformed as the scale increased,which could be caused by the various characteristic scales of different ecosystem services.In addition,the types,proportions,and attributes of ecosystem service bundles varied at different scales.Therefore,ecosystem services in mountainous cities should not be studied with coarse grain sizes.(5)In general,landscape composition is more influential to ecosystem services than landscape configuration.Forest bird habitat and water retention services were mainly depending on the proportion of forest.Waterfowl habitat and food production services were mainly driven by the proportion of water area and cultivated area,respectively.Nitrogen retention and phosphorus retention services were mainly decided by the proportion of cultivated area and forest.Soil retention service was mainly determined by slope.Heat island mitigation and recreation services were mainly depending on population density.Forest bird habitat,waterfowl habitat,nitrogen retention,phosphorus retention,heat island mitigation,and recreation services had thresholds with the change of landscape components.As for landscape configuration,fragmentation usually had greater impacts on ecosystem services than shape complexity because of complex and trans-scale ecological processes in most ecosystem services.(6)As the grain size increased,the ecosystem services became more predictable.We speculated there were three reasons: the intrinsic scales of some ecosystem services(e.g.,heat island mitigation)are large;the spatial heterogeneities of environmental and social variables(e.g.,road density)rise as the grain size decreases,which could increase the uncertainty of ecosystem services;large landscape units can provide more abundant supplies and demands of ecosystem service than the smalls,leading to more stable patterns of ecosystem services.(7)The interactions between landscape patterns and ecosystem services showed that the synergy between landscape patterns and ecosystem services is inevitable for optimizing greenspace in mountainous cities.Therefore,I proposed an ecological security planning framework for coupling habitat ecological network and ecosystem services protection,put forward a zoning plan for ecosystem services management,and identified priority promotion areas of water purification,heat island mitigation,and recreation services.The essential creative contributions of this thesis are to:(1)systematically integrate ideas,frameworks,and methods of landscape ecology and landscape sustainability science with regional landscape planning in the perspective of ecosystem service,and propose planning strategies and methods for improving ecosystem services;(2)use multidisciplinary methods and mass data to quantify spatial patterns of ecosystem services based on local conditions in the Chongqing metropolitan area;(3)reveal the tradeoffs,major impact factors,and impact rules of ecosystem services in mountainous cities at multi scales,and find the spatial heterogeneities of ecosystem services are driven by landscape characteristics in mountainous cities.