| Rapid urbanization in developing countries has been shown to demand higher intensity of development and more frequent humanecosystem interactions.Since the 1990s,the development process has been rapid and a series of achievements have been made.Urbanization in China is representative,poses severe risks if not irreversible consequences to the sustainability of natural ecosystem.The UN Sustainable Development Goals(SDGs)has highlighted the necessity to maintain harmony between the ecosystems and humanity for achieving a sustainable state.How to understand a series of ecological risk effects brought by Urbanization in China and coordinate the interaction between natural ecosystem and human society is a realistic problem that needs to be considered to realize the sustainable development model in today’s era.This article focused on the spatial coupling process of urbanization and ecological risk characterization factors at the multi-scale across the whole China and local typical regions.This study was evaluated based on three spatial scales(10km ×10km,2km × 2km,Province)over a 6-year time span of 1990,1995,2000,2005,2010,and 2015.The main research content are as follows:(1)the landscape ecological risk(LER)and population,economy,land and comprehensive urbanization levels across the country based on a 10km grid cell,and the coupling coordination status between LER and its leading urbanization factors,(2)the dynamics of ecosystem service value and comprehensive urbanization level in China based on provincial administrative units,and their coupling coordination status,(3)the ecosystem health and human interference in Gannan of typical ecological barrier regions of China based on 2km grid cells,and their temporal spatial relationship based on terrain gradient,and(4)the ecosystem service scarcity value(ESSV)and urbanization level in Yuebei of typical ecological barrier regions of China based on 2km grid cells,and the spatial heterogeneity response pattern of ESSV to urbanization progress.Through the above multi-angle risk characteristics,multi-research scale and multi-assessment scale studies,it can make contributions to comprehensively clarifying the dynamics of natural ecosystem under the background of urbanization and alleviating the contradiction between urban development and ecological protection of China in the future.The results indicate that:1.From 1990 to 2015,the level of landscape ecological risk in China increased slightly,and most of the hotspots were concentrated in the eastern,southern and central regions,while the hotspots in the western regions were dispersed.Hot spots correspond to water body,woodland and grassland in land types,and the closer these land types were to urban,the higher the risk level was.Population urbanization,economy urbanization,land urbanization and the comprehensive urbanization level measured by the three factors have been continuously improved during the study period.The main urbanization factors promoting the increase of LER in China include population density(PD),build-up land proportion(BLP)and comprehensive urbanization level(CUL).PD was dominant in the northern and eastern regions,BLP was dominant in the northeast and southwest regions,and CUL was dominant in the northwest,central and southern regions.Importantly,the level of coupling coordination between the three urbanization factors and LER increased over time,but most areas of China were still in a state of unbalanced development status in 1990-2015.2.From 1990 to 2015,the ecosystem services value(ESV)increased in only two provinces,Tibet and Qinghai,while it decreased in all other provinces,and the decline rate was higher in the provinces near the eastern part of China.In the same period,the CUL of all provinces increased,and the increase rate of provinces near the east was higher.In addition,the ESV was negatively correlated with urbanization,and its function curve was Ushaped.During the study period,the coupling coordination degree between ESV and urbanization increased,especially in 2015,indicating that the two were developing towards harmony.In terms of coupling type,there were great differences between eastern and western regions.Similarly,most provinces in China were still in an unbalanced development state,mainly concentrated in the central and western regions,while slightly balanced provinces were concentrated in the eastern regions.3.In 1990-2015,the ecosystem health(ESH)of Gannan in general was on the decline,mainly due to the lower gradient region on "Low"health and "Relatively low" level area increased and the "High" level area on the higher gradient region was reduced as a result.Hot spots of ESH were distributed in higher terrain gradient regions than cold spots.In addition,the degree of human interference in this area was obviously enhanced,and it was mainly concentrated in the lower gradient densely urban regions.The spatial correlation results showed that there was a significant negative correlation between ESH and human interference,and the correlation degree increased with time.At the same time,it also presented a significant spatial aggregation effect,and the terrain factors lead to the obvious differentiation between the two variables.The aggregation types were low health-high disturbance type and high healthlow disturbance type,the former was distributed around the city with lower gradient,and the latter was distributed in the mountain belt with higher gradient.4.From 1990 to 2015,the physical supply value of ecosystem services in Yuebei showed a downward trend,but the scarcity value of ecosystem services increased sharply during the same period,and the acceleration trend was particularly obvious after 2000.As woodland is the dominant land type in Yuebei,areas with higher scarcity value were mainly concentrated in the northern region.The urbanization level increased during the study period and accelerated significantly after 2000.Scarcity value and urbanization process showed similar dynamic trends during the same period.Surprisingly,spatial scarcity values were negatively correlated with urbanization,and their interaction intensifies over time.In addition,the spatial hot spots distribution of ESSV and urbanization showed opposite pattern.Among the aggregation types,the number of grid cells of high ESSV-low urbanization type and low ESSV-high urbanization type accounted for more than half of the total number of grid cells generating aggregation effect.In conclusion,the urbanization process in China did promote the increase of ecological risk,human disturbance had a negative ecological effect,and it also indicated that human society was closely related to the ecosystem.Therefore,the interaction between natural ecosystem and urbanization can provide a more accurate direction for resource adjustment and ecosystem improvement in the future,and contribute to alleviating human-nature contradiction and realizing steady and coordinated development through the four ecological risk characteristics of LER,ESV,ESH and ESSV. |
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