JIEFENG KANG

Urban forest, as an essential urban green infrastructure, is critical in providing ecosystem services to cities. To enhance the mainstreaming of ecosystem services in urban planning, it is necessary to explore the spatial pattern of urban forest ecosystem services in cities. This study provides a workflow for urban forest planning based on field investigation, i-Tree Eco, and geostatistical interpolation. Firstly, trees across an array of land use types were investigated using a sampling method. Then i-Tree Eco was applied to quantify ecosystem services and ecosystem service value in each plot. Based on the ecosystem services estimates for plots, four interpolation methods were applied and compared by cross-validation. The Empirical Bayesian Kriging was determined as the best interpolation method with higher prediction accuracy. With the results of Empirical Bayesian Kriging, this study compared urban forest ecosystem services and ecosystem service value across land use types. The spatial correlations between ecosystem service value and four types of point of interest in urban places were explored using the bivariate Moran's I statistic and the bivariate local indicators of spatial association. Our results show that the residential area in the built-up area of Kyoto city had higher species richness, tree density, ecosystem services, and total ecosystem service value. Positive spatial correlations were found between ecosystem service value and the distribution of urban space types including the tourist attraction distribution, urban park distribution, and school distribution. This study provides a specific ecosystem service-oriented reference for urban forest planning based on land use and urban space types.

Urbanization provides both challenges and opportunities for biodiversity conservation, but patterns of urban plant diversity across land uses, especially in Asian countries, remains unclear. To determine these patterns of diversity, woody plants in 174 sample quadrats across various land use types in Kyoto City were investigated. Richness, abundance, and evenness were evaluated at city, land use, and quadrat scales, and biodiversity of different land use types was compared. At the city level, 223 species in 77 families were recorded. At the land use level, residential areas had the highest total biological richness, with moderate to low evenness, while commercial areas exhibited low richness. At the quadrat level, the low-rise residential area had higher species richness than the other land uses. Species abundance and evenness in quadrats were significantly different across land use types for the canopy layer but not for the understory. The results provide insights into urban biodiversity design and management by identifying prior land uses for biodiversity improvement and by highlighting the contribution of residential private yards. Urban heterogeneity, scale, and multidimensionality should be considered when measuring urban biodiversity.

The demand for urban ecosystem services increases with the rapid growth of the urban population. The urban forest is a crucial ecosystem services provider in cities. To achieve a better estimation of urban ecosystem services, an understanding of the link between heterogeneity and ecosystem services within cities is needed. Other than street trees and forest remnants, the contribution of dispersed green spaces should also be considered. In this study, a ground-based sample quadrat investigation of trees across a sequence of land types in Kyoto City was applied. The ecosystem services and monetary values of trees were further calculated using a customized i-Tree Eco tool. The ecosystem services calculated include carbon storage and sequestration, air pollutants removal, and runoff reduction. Ecosystem services of different land use classes were compared at both quadrat and single-tree levels. We found no significant difference across land use for all the ecosystem services at the quadrat level. However, ecosystem services were different across land use at the single-tree level. We performed a species-specific analysis and found that the pattern of ecosystem services at the single-tree level across land use varies with both the service tested and species. Our study suggests that the heterogeneity within a city should be considered when estimating urban ecosystem services. The results also provide insight into the urban green space management of Kyoto City.

A general framework for the analysis of the urban water-energy nexus (WEN) was proposed and a dynamic and quantitative WEN model was developed based on the Long-range Energy Alternatives Planning System (LEAP) and Water Evaluation and Planning (WEAP) tools. Using Xiamen, China, as a case study, eleven future scenarios were designed to explore the impacts of different factors, from both supply and demand sides, on urban WEN. Both water-related energy (WRE) and energy-related water (ERW) were studied to reveal the interconnected relationship between water and energy. We found that most WRE and ERW savings lie on the supply side, except for demand management scenarios, and most scenarios have larger trans-boundary effects than in-boundary effects due to the import of large quantities of energy and water. Industry structure adjustments (oriented toward energy or water savings) and energy-saving measures have better co-benefits in terms of energy and water savings than other measures. Promoting electric vehicles increases electricity imports and related trans-boundary ERW. Such effects should be considered before importing resources from outside city boundaries. Developing high-tech industries might also increase energy or water burdens. Finally, the boundaries of urban WEN research were discussed to promote additional comparable studies. (C) 2019 Elsevier Ltd. All rights reserved.

A water evaluation and planning model (WEAP) for Xiamen City was used to analyze trends in water use and demand between 2015 and 2050. This study was unique in that it considered the water resources of each of the city's five districts' separately, rather than the city as a whole. The water saving potential, water shortages, and water supply alternatives were analyzed under different simulated scenarios. The results show that future water consumption will greatly increase in Xiamen City, and that there will be a water shortage after 2030 without new water supplies. Water shortages will first occur in the Tongan and Xiangan districts, due to established water supply priorities and capacity. Industry restructuring (structural water-saving scenario, SWS) and advanced water-saving technology (technical water-saving scenario, TWS) can result in water saving potentials of 6.97% and 9.82% by 2050, respectively, while adopting both strategies (double water-saving scenario, DWS) can save 16.44%. The prevention of future water shortages requires the implementation of water-saving measures and the use of new water supplies.

Because cities are key to Chinese GHG management, a LEAP-based model integrating energy-related and non-energy related sectors was developed to study urban CO2 and GHG peak volume and time. Using Xiamen City as a case study, the future GHG emissions trends from 2015 to 2050 was simulated under three scenarios, namely a business-as-usual scenario (BAU), an emission-controlled scenario (EC), and a reinforced mitigation scenario (RM). Results show that Xiamen City will peak its total GHG emissions in 2039 under EC scenario and 2034 under RM scenario, while there might not be an obvious GHG peak under BAU scenario before 2050. Total CO2 emissions will peak at the same year as the GHG emissions peak year under EC and RM scenarios. Our research also indicates that population and economic growth has a significant impact on the city's CO2 and GHG peak, and Xiamen might reach the CO2 peak later than the national goal due to clean energy supply limitations and continued rapid growth. Lack of favorable conditions for large-scale renewable energy development and relatively high price of natural gas are the main obstacles for CO2 and GHG reduction in Xiamen City. In the future, greater attention on multi-sector reduction strategies is needed, including transforming industrial structure, expanding public transport while limiting private car growth, controlling per capita residential living area, improving public building energy efficiency, and reducing and reusing waste. (C) 2017 Elsevier Ltd. All rights reserved.

The consumption-based carbon footprint (CBF) can facilitate the implementation of broader mitigation policies that concern final consumption. Here, a city-centric global multiregional input-output model (CCG-MRIO) was developed to assess the carbon footprints of urban consumption in the global supply chain. Beijing was selected as the studied case, and results were as follow. In 2010, Beijing's CBF was 338.26 Mt CO(2)e, which was 1.90 times amount of its purely geographic accounting (PGA). Manufacturing, services, and construction were the top three consumers, while Mainland China and other developing regions were the main net importing areas, and utilities, manufacturing, and agriculture were the top net importing sectors. These findings indicated that Beijing imports large amounts of energy, water, and raw materials to support its consumption, while it mainly exports services and industrial products. The study fills the gap of data and methods for urban CBF compiling and can replicate to other cities with an input-output table. The CBF can promote sustainable local consumption behaviors, local production efficiencies improvement, and cooperation with importing regions. However, the model uncertainties increase in coordinating sectors, estimating trade relationship, and ignoring traffic differences; and the availability of municipal input-output table and energy data hinder its application.

Providing a comprehensive insight, water footprint (WF) is widely used to analyze and address wateruse issues. In this study, a hybrid of bottom-up and top-down methods is applied to calculate, from production and consumption perspectives, the WF for Xiamen city from 2001 to 2012. Results show that the average production WF of Xiamen was 881.75 Mm(3)/year and remained relatively stable during the study period, while the consumption WF of Xiamen increased from 979.56 Mm(3)/year to 1,664.97 Mm(3)/year over the study period. Xiamen thus became a net importer of virtual water since 2001. Livestock was the largest contributor to the total WF from both production and consumption perspectives; it was followed by crops, industry, household use, and commerce. The efficiency of the production WF has increased in Xiamen, and its per capita consumption WF was relatively low. The city faces continuing growth in its consumption WF, so more attention should be paid to improving local irrigation, reducing food waste, and importing waterintensive agricultural products.

Decomposition of the urban water footprint can provide insight for water management. In this paper, a new decomposition method based on the log-mean Divisia index model (LMDI) was developed to analyze the driving forces of water footprint changes, attributable to food consumption. Compared to previous studies, this new approach can distinguish between various factors relating to urban and rural residents. The water footprint of food consumption in Xiamen City, from 2001 to 2012, was calculated. Following this, the driving forces of water footprint change were broken down into considerations of the population, the structure of food consumption, the level of food consumption, water intensity, and the population rate. Research shows that between 2001 and 2012, the water footprint of food consumption in Xiamen increased by 675.53 Mm(3), with a growth rate of 88.69%. Population effects were the leading contributors to this change, accounting for 87.97% of the total growth. The food consumption structure also had a considerable effect on this increase. Here, the urban area represented 94.96% of the water footprint increase, driven by the effect of the food consumption structure. Water intensity and the urban/rural population rate had a weak positive cumulative effect. The effects of the urban/rural population rate on the water footprint change in urban and rural areas, however, were individually significant. The level of food consumption was the only negative factor. In terms of food categories, meat and grain had the greatest effects during the study period. Controlling the urban population, promoting a healthy and less water-intensive diet, reducing food waste, and improving agriculture efficiency, are all elements of an effective approach for mitigating the growth of the water footprint.

Cities are hotspots of socio-economic activities and greenhouse gas emissions. The aim of this study was to extend the research range of the urban carbon footprint (CF) to cover emissions embodied in products traded among regions and intra-city sectors. Using Xiamen City as a study case, the total urban-related emissions were evaluated, and the carbon flows amongregions and intra-city sectors were tracked. Then five urban CF accountings were evaluated, including purely geographic accounting (PGA), community-wide infrastructure footprint (CIF), and consumption-based footprint (CBF) methods, as well as the newly defined production-based footprint (PBF) and purely production footprint (PPF). Research results show that the total urban-related emissions of Xiamen City in 2010 were 55.2 Mt CO(2)e/y, of which total carbon flow among regions or intra-city sectors accounted for 53.7 Mt CO(2)e/y. Within the total carbon flow, import and export respectively accounted for 59 and 65%, highlighting the importance of emissions embodied in trade. By regional trade balance, North America and Europe were the largest net carbon exported-to regions, and Mainland China and Taiwan the largest net carbon imported-from regions. Among intra-sector carbon flows, manufacturing was the largest emission-consuming sector of the total urban carbon flow, accounting for 77.4, and 98% of carbon export was through industrial products trade. By the PBF, PPF, CIF, PGA and CBF methods, the urban CFs were respectively 53.7 Mt CO(2)e/y, 44.8 Mt CO(2)e/y, 28.4 Mt CO(2)e/y, 23.7 Mt CO(2)e/y, and 19.0 Mt CO(2)e/y, so all of the other four CFs were higher than the CBF. All of these results indicate that urban carbon mitigation must consider the supply chain management of imported goods, the production efficiency within the city, the consumption patterns of urban consumers, and the responsibility of the ultimate consumers outside the city.

A carbon footprint accounting of food production is useful for acquainting policy makers with both the potentials and the challenges of GHG mitigation in agriculture. In this study, a hybrid Economic Input-Output and Life Cycle Assessment (EIO-LCA) model was developed to investigate the carbon footprint of Chinese food production from 1979 to 2009. The change patterns and compositions of emission sources, impacts of urbanization, carbon footprint and carbon emission factors of 15 food types were examined. Research results indicate that the total carbon footprint of food production had doubled in those three decades, alongside rapid urbanization. The emission sources showing the most dramatic increases were synthetic fertilizer, direct energy use, enteric fermentation and manure management. Among all types of food, the carbon footprint of rice production increased most, and the carbon footprint of milk, bovine meat, fruit and vegetable production also grew rapidly due to increasing yields. There was an overall decreasing trend for carbon emission factors of rice, vegetable, fruit and animal-food production from 1979 to 2009. Notably, the carbon emission factors of most vegetable food production rebounded after hitting bottom in 1999 due principally to enhanced agricultural input. Compared with the U.S.A., China had a higher ratio of indirect carbon footprint in its food production system, which showed high material input and energy intensity. China had smaller carbon emission factors from rice and pigmeat production, but larger carbon emission factors from bovine meat production than the U.S.A., indicating the relative strengths and weaknesses of Chinese food-production technology. Mitigation solutions rely upon better balancing the dietary structure, improving the productivity of animal foods, and reducing agricultural inputs, especially synthetic fertilizer. (C) 2014 Elsevier Ltd. All rights reserved.