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The structure and “metabolism” (movement and conversion of goods and energy) of urban areas has caused cities to be identified as “super-organisms”, placed between ecosystems and the biosphere, in the hierarchy of living systems. Yet most such analogies are weak, and render the super-organism model ineffective for sustainable development of cities. Via a cluster analysis of 15 shared traits of the hierarchical living system, we found that industrialized cities are more similar to eukaryotic cells than to multicellular organisms; enclosed systems, such as factories and greenhouses, paralleling organelles in eukaryotic cells. We further developed a “super-cell” industrialized city model: a “eukarcity” with citynucleus (urban area) as a regulating centre, and organaras (enclosed systems, which provide the majority of goods and services) as the functional components, and cityplasm (natural ecosystems and farmlands) as the matrix. This model may improve the vitality and sustainability of cities through planning and management. publishedVersion

Quantifying the irrigation water demand of green spaces (IWDG) is an important part of smart urban water management. However, the IWDG in humid cites is not well characterized. Moreover, the alteration of natural hydrological processes caused by urbanization leading to the dependence of green spaces on irrigation is becoming more common. To better understand the IWDG in humid areas, we developed an estimation model and used the Yangtze River Delta in China as a case study. Results showed that the amount of water required by the green spaces in the Yangtze River Delta was approximately 354 × 106 m3, which was equivalent to 12% of the urban residential water consumption in 2011. This study also investigated the spatial-temporal changes of urban green spaces and estimated their effects on irrigation water demand. These findings provide policymakers an integrated view of the water demand of green spaces associated with sustainable management.

A challenge in urbanization is how to improve the usage of temporary fragmented land, alleviate land degradation and ensure food self-sufficiency. The greenhouses for cultivation have the potential to utilize the fragmented lands, yet there are little known of their spatial information. This study developed a framework to visually identify greenhouses and mapped the spatial pattern through the Google Earth Engine. Based on the investigation of 28,700 plots in three cities in China, it has found that: (1) the greenhouses distribution peaked at 1−2 km outside the built-up area; (2) more than 60 % of the greenhouses are less than 0.5 ha and the area increase with the distance from city center, which enabled the greenhouses to adapt to the fragmented lands; (3) the economic returns (average 2,400 yuan ha−1 yr−1) were much higher than the environmental impacts related to land degradation (500 yuan ha−1 yr−1); and (4) the economic returns provided by the greenhouses near urban fringes were higher than those in the rural, indicating the economic incentives and feasibility of greenhouse cultivation in urban fringes. This study will help decision-makers to form more effective strategies for utilizing temporary fragmented and degraded land to contribute to sustainable development of cities.

Understanding the relationships among ecosystem services is crucial for ecosystem-based management (EBM). In urbanized areas, improving human well-being increasingly depends on the services provided by human-dominated or artificial ecosystems. However, there is little understanding of the relationships among multiple ecosystem services of human-dominated ecosystems. Based on the methodology of ecosystem service bundles (sets of ecosystem services that repeatedly appear together), we conducted a case study in 22 urban–rural complexes across the Yangtze River Delta, the most developed area of China, to explore the spatial distributions, synergies, and trade-offs of multiple ecosystem services. Results showed that: (1) most of the selected ecosystem services were spatially clumped across the study area, and the distribution of ecosystem services contributes to the formation of scale effect in economy for the provision of services; (2) ecosystem service bundles aggregated spatially at the city cluster scale, implying the aggregate feature of bundles might be scale free; (3) trade-offs occurred mainly between land-dependent services (such as crop production and water supply), while synergies occurred mainly between land-independent services (such as manufactured products and students of higher education), and there were no significant relationships between landdependent and land-independent services; (4) compared with geographic factors, socio-economic factors were the major drivers in the formation of ecosystem service bundles in the heavy urbanized region of the Yangtze River Delta. The study could improve the understanding of the relationships among multiple ecosystem services from local to regional scales.

Human activities are strongly modifying the global nitrogen (N) cycle through increasing input, N species diversity, and pool size of industrial reactive N (Nr). However, the fluxes, fates and environmental consequences of industrial Nr (excluding synthesized N fertilizer) remain poorly understood and quantified. We report here that industrial Nr flux has increased 13.4-fold over the past 30 years in China, reaching 3.7 Tg N (1 Tg = 1012 g) in 2008, accounting for over 50% of China’s food Nr flux. Socioeconomic development (per capita GDP, urbanization and household size) significantly drives the growth of industrial Nr fluxes. This leads to “hotspots” of industrial Nr, mainly in relatively developed Eastern China. Industrial Nr loss rate during production is only 5%, much lower than that of cropland (50%) and livestock (80%). However, industrial Nr loss is point source pollution, and Nr release in concentrated doses produces serious risk in small regions. The contribution of structural N to total industrial Nr with a lifespan longer than one year (e.g., synthetic fiber, plastic) increased from 20% in 1980 to 70% in 2008. There was about 2.6 Tg N structural industrial Nr accumulated in human settlements in 2008, which could be one explanation of an unknown Nr sink of anthropogenic Nr input (mainly Haber-Bosch N fixation). Legacy effects caused by structural N accumulation have long-term consequences for environmental and human health, although structural N delays Nr release and reduces short-term Nr pollution. Industrial Nr use generates new features of modern global N biogeochemistry, such as increasing Nr species diversity, reducing Nr turnover rate. Future dynamics simulation of the earth system should involve industrial Nr. Explicit consideration and accounting of the fluxes and environmental consequences of industrial Nr would provide decision-makers a novel view of regional sustainable development.