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Guo G.,CAS Guangzhou Institute of Geochemistry | Guo G.,University of Chinese Academy of Sciences | Guo G.,Guangdong Institute of Eco environmental and Soil Sciences | Wu Z.,Guangzhou University | And 6 more authors.
Landscape and Urban Planning | Year: 2015

The spatio-temporal pattern of biophysical composition significantly affects land surface temperature (LST). Previous studies, however, mostly characterized urban heat island (UHI) clusters being spatially homogeneous. The landscape spatial heterogeneity in urban across UHI clusters challenges us to more accurately characterize the relationships between LST and corresponding urban biophysical composition. In this study, we introduced an innovative integrated approach that combined object-oriented image segmentation with local indicators of spatial autocorrelations (LISA) to extract UHI clusters from an LST image. We used a regression tree model to examine the nonlinear relationships between LST and each of three satellite-based indices within the UHI clusters: normalized differential vegetation index (NDVI), normalized differential build-up index (NDBI), and normalized difference bareness index (NDBaI). We found that both NDVI and NDBI are strongly correlated with the variations of LST whereas NDBaI has a weaker correlation with LST. We also found that the regression tree model built in this study enabled us to effectively detect the nonlinear relationship between LST and biophysical composition. Furthermore, based on a set of rules derived from a regression tree analysis, we found that urban landscapes strongly affect LST and its spatial heterogeneity within a UHI. These rules were used to detect the nonlinear impacts of complex urban biophysical composition on LST. The results of this study provided insights into how LST within UHI varies with urban surface characteristics at fine spatial scale and also a new method for investigating effects of land surface composition on LST in urbanized areas. © 2014 Elsevier B.V.


Guo G.,Guangzhou University | Zhou X.,Guangzhou University | Wu Z.,Guangzhou University | Xiao R.,Guangdong Provincial Academy of Environment Science | Chen Y.,Guangzhou University
Environmental Modelling and Software | Year: 2016

The urban morphology is regarded as one of the main reasons for urban heat island (UHI). However, its effect on UHI in city-scale urban areas has seldom been examined. In this paper, we presented a rule-based regression model for investigating the nonlinear relationship between land surface temperature (LST) and urban morphology represented by building height, building density and sky view factor (SVF) across different dates in 2005. Results found that an urban morphology of medium building height and lower density significantly yielded higher LST variation levels, whereas the lowest LST variation levels occurred in high-rise and high-dense building arrays. Compared to building height, building density had a stronger influence on LST. Medium SVF values produced the lowest LST, whereas the largest and smallest SVF values produced the highest LST. Results also showed how rule-based regression model offer great performance in detecting the nonlinear mechanisms of LST as well. © 2016 Elsevier Ltd


Zhou J.,Guangdong Provincial Academy of Environment Science | Xiao R.-B.,Guangdong Provincial Academy of Environment Science | Sun X.,South China University of Technology
Chinese Journal of Applied Ecology | Year: 2013

Settlement morphology transition is triggered by rapid urbanization and urban expansion, but its relationships with residents commuting energy consumption remains ambiguous. It is of significance to understand the controlling mechanisms of sustainable public management policies on the energy consumption and greenhouse gases emission during the process of urban settlement morphology transition. Taking the Xiamen City of East China as a case, and by using the integrated land use and transportation modeling system TRANUS, a scenario analysis was made to study the effects of urban settlement morphology transition on the urban spatial distribution of population, jobs, and land use, and on the residents commuting energy consumption and greenhouse gasses emission under different scenarios. The results showed that under the Business As Usual (BAU) scenario, the energy consumption of the residents at the morning peak travel time was 54.35 tce, and the CO2 emission was 119.12 t. As compared with those under BAU scenario, both the energy consumption and the CO2 emission under the Transition of Settlement Morphology (TSM) scenario increased by 12%, and, with the implementation of the appropriate policies such as land use, transportation, and economy, the energy consumption and CO2 emission under the Transition of Settlement Morphology with Policies (TSMP) scenario reduced by 7%, indicating that urban public management policies could effectively control the growth of residents commuting energy consumption and green-house gases emission during the period of urban settlement morphology transition.


Zhou J.,Guangdong Provincial Academy of Environment Science | Xiao R.-B.,Guangdong Provincial Academy of Environment Science | Sun X.,Guangdong Provincial Academy of Environment Science
Ying yong sheng tai xue bao = The journal of applied ecology / Zhongguo sheng tai xue xue hui, Zhongguo ke xue yuan Shenyang ying yong sheng tai yan jiu suo zhu ban | Year: 2013

Settlement morphology transition is triggered by rapid urbanization and urban expansion, but its relationships with residents commuting energy consumption remains ambiguous. It is of significance to understand the controlling mechanisms of sustainable public management policies on the energy consumption and greenhouse gases emission during the process of urban settlement morphology transition. Taking the Xiamen City of East China as a case, and by using the integrated land use and transportation modeling system TRANUS, a scenario analysis was made to study the effects of urban settlement morphology transition on the urban spatial distribution of population, jobs, and land use, and on the residents commuting energy consumption and greenhouse gasses emission under different scenarios. The results showed that under the Business As Usual (BAU) scenario, the energy consumption of the residents at the morning peak travel time was 54.35 tce, and the CO2 emission was 119.12 t. As compared with those under BAU scenario, both the energy consumption and the CO2 emission under the Transition of Settlement Morphology (TSM) scenario increased by 12%, and, with the implementation of the appropriate policies such as land use, transportation, and economy, the energy consumption and CO2 emission under the Transition of Settlement Morphology with Policies (TSMP) scenario reduced by 7%, indicating that urban public management policies could effectively control the growth of residents commuting energy consumption and greenhouse gases emission during the period of urban settlement morphology transition.


Zhou J.,Guangdong Provincial Academy of Environment Science | Xiao R.B.,Guangdong Provincial Academy of Environment Science | Zhuang C.W.,Guangdong Provincial Academy of Environment Science | Deng Y.R.,Guangdong Provincial Academy of Environment Science
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2013

Urban forest and relevant management policies have been widely considered as a tool to mitigate carbon dioxide (CO2) emissions. However, the urban forest structure, function and role in carbon(C) offsets of Chinese urban forests are little understood. The main objective of this study was to evaluate the C storage and sequestration by urban forests and C emissions from energy consumption by urban energy consumption in Guangzhou, and analyse the effect of urban forests offsetting the C emissions from energy use. This paper also discussed the relationship between urban low carbon development and forest C sink, and explored the management practices for improving Guangzhou's urban forest function of offsetting C emissions. Guangzhou is located in north side of the Pearl River, along southeastern coast of China. The forests in Guangzhou includes five main types: Eucalyptus, Plus massoniana, Cunninghamia lanceolata, economic forest and evergreen broad-leaved forest. C storage and sequestration were quantified using urban forest inventory data and by applying volume-derived biomass equations and other models related to net primary productivity (NPP). C emissions from urban energy use were estimated by accounting for fossil fuel use and C emission factors. Total C storage by Guangzhou's urban forests was estimated at 654.42×104 t, and average C density was 28.81 t/ hm2. C storage in different districts ranged from 1.50×104 t to 354.99×104 t, as in the following order: Conghua>Zengcheng>Huadu>Baiyun>Luogang>Panyu>Tianhe> Huangpu. C storage of evergreen broad-leaved forest and young age class forest were respectively 530.67×104 t and 271.86× 104 t, which had played a chief role in forest total C storage in terms of forest type and age class. C sequestration by urban forests was 658,732 t/ a, with an average C sequestration rate was 2. 90 t·hm-2·a-1. The spatial distribution of C sequestration in Guangzhou was imbalanced: most of C was sequestrated in exurb just like Conghua and Zengcheng. The C sequestration percentages of Eucalyptus, Plus massoniana, Cunninghamia lanceolata, economic forest and evergreen broad- leaved forest were 6.25%, 8.13%, 3.67%, 1.48% and 82.25% respectively. C sequestration rate decreased with increasing forest age. For Eucalyptus, C sequestration for young, middle-aged, premature, mature and post-mature forests decreased with age from 3.06 t·hm-2·a-1 to 2.35 t·hm-2·a-1. Results were similar for Plus massoniana which decreased from 1.99 t·hm-2·a-1 to 1.34 t·hm-2·a-1, for Cunninghamia lanceolata from 4.06 t·hm-2·a-1 to 2.61 t·hm-2·a-1, and for evergreen broad-leaved forest from 4.17 t·hm-2·a-1 to 3.68 t·hm-2·a-1. Average annual C emissions of urban energy use from 2005 to 2010 in Guangzhou were 2907.41×104 t. Therefore, the C stored by urban forests equaled 22.51% of the average annual C emission from fossil fuel use, and C sequestration could offset 2.27% of the average annual C emission in Guangzhou. Urban forest's C sequestration had a small contribution on urban carbon reduction, but it is still one of the important measures of low carbon development from its comprehensive benefits such as releasing Oxygen, air purification, VOC(volatile organic compounds)management, stormwater runoff capture, building energy saving, aesthetics and recreation. Furthermore, this paper also analyzed the impacts of forest composition and forest age structure on C storage and sequestration of urban forests in Guangzhou, and gave suggestions on improving forest C sink to enhance C offset effect through the forest management.

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