Zong Y.,University of Hong Kong |
Kemp A.C.,University of Pennsylvania |
Yu F.,Durham University |
Lloyd J.M.,Durham University |
And 2 more authors.
Marine Micropaleontology | Year: 2010
We collected 77 modern diatom samples from sites across the Pearl River estuary, China to analyze the relationship between diatom assemblages and environmental parameters including water salinity, water depth and sediment particle size. Results showed that marine diatoms were dominant in the high salinity environment around Hong Kong and the outer part of the estuary. Brackish water diatoms were found in high abundance in the central part of the estuary. Both marine and brackish water diatoms were predominantly planktonic taxa. Freshwater diatoms dominated in low salinity environments, with planktonic taxa in the deep tidal channel and benthic species in the shallow deltaic distributaries. Statistical tests indicated that the modern diatom distribution is strongly correlated with salinity but is also influenced by several other environmental variables including sand content and water depth. Transfer functions relating diatom assemblages and water salinity had high r2 (0.94-0.98 for WA-PLS, 0.95 for MA and 0.98 for MAT) and relatively low RMSEP (2.66-1.63‰ for WA-PLS, 2.35‰ for MA and 2.70‰ for MAT). Due to the geographical distribution of samples, some spatial autocorrelation is likely present in the dataset. When this effect is considered, r2 decreases to 0.90 and RMSEP increases to 5.41‰, although the diatom-salinity relationship remains appropriate for reconstructing paleosalinity. Based on this estimate, a diatom-based salinity transfer function with high accuracy and precision is developed and successfully applied to a sediment core for quantitative reconstruction of the Holocene paleosalinity in the Pearl River estuary. © 2010 Elsevier B.V. All rights reserved.
Chen S.,Guangzhou Institute of Geography |
Han L.,Shandong University of Technology |
Chen X.,CAS South China Botanical Garden |
Li D.,Guangzhou Institute of Geography |
And 2 more authors.
ISPRS Journal of Photogrammetry and Remote Sensing | Year: 2015
The objective of this study was to evaluate the performance of moderate resolution imaging spectroradiometer (MODIS) 250m based TSS (Total Suspended Solids) retrieval model for developing the model of wide-range TSS concentrations. Using field spectral and TSS data (5.8-577.2mg/l) collected from estuary and coast of China, we calibrated (N=40) and validated (N=20) the 6 TSS retrieval models in forms of single band (B1 or B2), difference of the two bands, sediment index, band ratio and log-ratio by the least-squares technique. Results showed that the quadratic model of log-ratio is of the best accuracy (Calibration: R2=0.752, N=40. Validation: TSS>31mg/l, RMSE=37.9mg/l, N=12; TSS≤31mg/l, RMSE=3.25mg/l, N=8). We also found that the spectral log-ratio values increased with the increasing of TSS when TSS<31mg/l, but decreased with increasing TSS when TSS>31mg/l. The findings of quadratic curve vertex (log-ratio: ~1.58) in the proposed TSS model indicated that the spectral log-ratio may be sensitive to TSS of both low and high concentrations. We further applied the preferred model to retrieve TSS concentration from the MODIS 250-m images in turbid estuarial and clear coastal waters, and obtained a good mapping accuracy from the result (TSS>31mg/l: RMSE=38.6mg/l, MRE=24.7%, N=17; TSS≤31mg/l: RMSE=2.1mg/l, MRE=19.5%, N=11). The vertex-based methodology of TSS model developed in the study is applicable in mapping TSS concentrations that are of a wide range variation in estuarine and coastal water bodies based on MODIS 250-m image, and as well to maximize its application potential due to high imaging frequency (two times during daytime) and appropriate space resolution of MODIS images. Therefore, the method can be used to detect the high temporal variability of TSS during tidal cycle. As such, the application of MODIS-water quality detection technology can be extended to coastal sediment movement. © 2014 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS).
Wang S.,Sun Yat Sen University |
Fang C.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research |
Wang Y.,Guangzhou Institute of Geography
Renewable and Sustainable Energy Reviews | Year: 2016
This paper examines carbon dioxide (CO2) emissions from the perspective of energy consumption, detailing an empirical investigation into the spatiotemporal variations and impact factors of energy-related CO2 emissions in China. The study, which is based on a provincial panel data set for the period 1995-2011, used an extended STIRPAT model, which was in turn examined using System-Generalized Method of Moments (Sys-GMM) regression. Results indicate that while per capita CO2 emissions in China were characterized by conspicuous regional imbalances during the period studied, regional inequality and spatial autocorrelation (agglomeration) both decreased gradually between 1995 and 2011, and the pattern evolutions of emissions evidenced a clear path dependency effect. The urbanization level was found to be the most important driving impact factor of CO2 emissions, followed by economic level and industry proportion. Conversely, tertiary industry proportion constituted the main inhibiting factor among the negative influencing factors, which also included technology level, energy consumption structure, energy intensity, and tertiary industry proportion. Importantly, the study revealed that the CO2 Kuznets Curve (CKC), which describes the relation between CO2 emissions and economic growth, in fact took the form of N-shape in the medium- and long-term, rather than the classical inverted-U shape of the environmental Kuznets Curve (EKC). Specifically, an additional inflection appeared after the U-shape relationship between economic growth and CO2 emissions, indicating the emergence of a relink phase between the two variables. The findings of this study have important implications for policy makers and urban planners: alongside steps to improve the technology level, accelerate the development of tertiary industry, and boost recycling and renewable energies, the optimization of a country's energy structure that can in fact reduce reliance on fossil energy resources and constitute an effective measure to reduce CO2 emissions. © 2015 Elsevier Ltd.
Zong Y.,University of Hong Kong |
Huang K.,Guangzhou University |
Yu F.,Nanyang Technological University |
Zheng Z.,Guangzhou University |
And 4 more authors.
Quaternary Science Reviews | Year: 2012
The early Holocene history of the Pearl River delta is reconstructed based on a series of sediment cores obtained from one of the main palaeo-valleys in the basin. Sedimentary and microfossil diatom analyses combined with radiocarbon dating provide new evidence for the interactions between sea-level rise, antecedent topography and sedimentary discharge changes within the deltaic basin since the last glacial. These new records show that river channels of last glacial age incised down to c. -40 m into an older (possibly MIS5 age) marine sequence which forms the floor of the deltaic basin and exists primarily at c. 10 m-15 m below present mean sea level. Rapid postglacial sea-level rise flooded the incised valleys by the beginning of the Holocene, and prior to c. 9000 cal. years BP, marine inundation was largely confined within these incised valleys. The confined available accommodation space of the incised valleys combined with strong monsoon-driven freshwater, high sediment discharge and a period of rapid rising sea level meant that sedimentation rates were exceptionally high. Towards c. 8000 cal. years BP as sea level rose to about -5 m, marine inundation spilled out of the incised valleys and the sea flooded the whole deltaic basin. As a result, the mouth of the Pearl River was forced to retreat to the apex of the deltaic basin, water salinity within the basin increased markedly as the previously confined system dispersed across the basin, and the sedimentation changed from fluvial dominated to tidal dominated. Sea level continued to rise, albeit at a much reduced rate between 8000 and 7000 cal. years BP, and deltaic sedimentation was concentrated around the apex area of the basin. During the last 7000 cal. years BP, the delta shoreline moved seawards, and the sedimentary processes changed gradually from tidal dominated to fluvial dominated. © 2012 Elsevier Ltd.
Yang L.,CAS South China Botanical Garden |
Yang L.,Guangzhou Institute of Geography |
Ren H.,CAS South China Botanical Garden |
Liu N.,CAS South China Botanical Garden |
Wang J.,CAS South China Botanical Garden
Journal of Vegetation Science | Year: 2010
Questions: What are the nurse effects of Rhodomyrtus tomentosa in degraded land of South China? Are canopy or soil factors responsible for the main nurse effect? Do facilitative effects increase with the shade tolerance of the target species? Location: Degraded shrubland in South China. Methods: Seedlings of three native climax woody species (Schima superba, Michelia macclurei, Castanopsis fissa) that differ in shade tolerance were subjected to four treatments by transplantation: (1) under the canopy of R. tomentosa shrubs; (2) in open interspaces without vegetation cover (control); (3) under the canopy of R. tomentosa from which canopies had been removed; and (4) in open interspaces without vegetation but covered by branches and leaves of R. tomentosa. Results: At low soil nutrient levels, increased canopy shade, soil porosity and soil moisture under the canopy of R. tomentosa increased seedling survival of the climax tree species S. superba, C. fissa and M. macclurei, and shoot height of S. superba. The nurse effect (a form of facilitation) of R. tomentosa depended more on canopy shade than on soil amelioration. The magnitude of facilitation or nurse effect was positively correlated with shade tolerance of the target species. Conclusions: Use of nurse plants in restoration differs from traditional reforestation (clearing and/or burning to reduce interspecific competition between target tree species and non-target species) because it focuses on positive interactions between nurse plants and target plants that increase establishment of target species and reduce time required for restoration. Because nurse effects of R. tomentosa shrubs tended to be larger on target species with greater shade tolerance, shade-tolerant plants are suggested as target species to accelerate restoration. © 2009 International Association for Vegetation Science.
Lu S.,Beijing Forestry University |
Guan X.,National Academy for Mayors of China |
Zhou M.,Huazhong University of Science and Technology |
Wang Y.,Guangzhou Institute of Geography
Environmental Management | Year: 2014
A large number of mathematical models have been developed to support land resource allocation decisions and land management needs; however, few of them can address various uncertainties that exist in relation to many factors presented in such decisions (e.g., land resource availabilities, land demands, land-use patterns, and social demands, as well as ecological requirements). In this study, a multi-objective interval-stochastic land resource allocation model (MOISLAM) was developed for tackling uncertainty that presents as discrete intervals and/or probability distributions. The developed model improves upon the existing multi-objective programming and inexact optimization approaches. The MOISLAM not only considers economic factors, but also involves food security and eco-environmental constraints; it can, therefore, effectively reflect various interrelations among different aspects in a land resource management system. Moreover, the model can also help examine the reliability of satisfying (or the risk of violating) system constraints under uncertainty. In this study, the MOISLAM was applied to a real case of long-term urban land resource allocation planning in Suzhou, in the Yangtze River Delta of China. Interval solutions associated with different risk levels of constraint violation were obtained. The results are considered useful for generating a range of decision alternatives under various system conditions, and thus helping decision makers to identify a desirable land resource allocation strategy under uncertainty. © 2014 Springer Science+Business Media.
Ye Y.,Guangzhou Institute of Geography |
Zhang H.,Guangzhou Institute of Geography |
Liu K.,Guangzhou Institute of Geography |
Wu Q.,Guangzhou Institute of Geography
International Journal of Applied Earth Observation and Geoinformation | Year: 2012
Landsat TM images of the Pearl River Delta taken in 1988, 1998 and 2006 are used to explore the site factors that influence the construction land expansion in this study. Several site factors, including landscape types and the distances to roads, coastlines, or city centers, had significant impacts on the expansion of construction land, influencing the direction, scale and intensity of the expansion. The site factors serve as important natural and spatial indicators of the preferable locales for construction land expansion, describing tendencies to expand to locations in suburbs, plains and areas near roads or coastlines. © 2011 Elsevier B.V.
Li X.,Guangzhou Institute of Geography
Acta Geographica Sinica | Year: 2014
Taking Acta Geographica Sinica (AGS), Journal of Geographical Sciences (JGS), Annals of the Association of American Geographers (AAAG) and Transactions of the Institute of British Geographers (TIBG) as typical representatives of mainstream journals in China and western countries, according to the information from the respective official websites and documents, and with the background and development history of each journal, the author of this paper makes a comparative analysis on the aims of the journals, report content, internationalization degree, characteristics and their requirement for the articles. The results show that: 1) In terms of the arms of publication, AAAG and TIBG focus on their discipline construction, express definitely their high orientation of international authority, and emphasize contribution of publication to the discipline knowledge, i.e. they have specific and definite requirements for innovativeness, while AGS and JGS, in addition to serving the discipline construction, put forward their objective to serve national economic construction, and emphasize the high level and originality of publication. 2) On the report content, AAAG laid stress on physical geography for its publication in the first two decades, but human geography has been in a dominant position in the following period; attention is also paid to environment science and geographical methodology in recent years; and basic theory study for geography is deepening, but the publication tendency of weakening physical geography becomes a problem faced by the comprehensive geography journals. For the publication of AGS, the ratio of physical geography and human geography is reasonably balanced. JGS pays attention to physical geography and comprehensive research involving physical and human geography. Both of them lay stress on empirical research articles. 3) As for the degree of internationalization, the authors of all selected journals are mainly from their own country, the international authors mostly come from USA, UK, and Canada. The internationalization degree of authors of AAAG is the highest, and the internationalization degree of editors and editorial boards of those journals is similar to that of the authors, with a slight difference, the proportion of international editorial members in TIBG is the highest, but the number of international editorial members of AAAG is the biggest. As international mainstream journals, they are all included by the most important international retrieval systems. 4) As for journal characteristics, AGS and JGS pay more attention to empirical research; AAAG mainly features in the special issues and the presidential speech, and TIBG is mainly embodied in virtual issues and articles' contribution requirements.
Lv Z.-Q.,Chongqing Technology and Business University |
Dai F.-Q.,Chongqing Technology and Business University |
Sun C.,Guangzhou Institute of Geography
Environmental Monitoring and Assessment | Year: 2012
Urban sprawl is a worldwide phenomenon happening particularly in rapidly developing regions. A study on the spatiotemporal characteristics of urban sprawl and urban pattern is useful for the sustainable management of land management and urban land planning. The present research explores the spatiotemporal dynamics of urban sprawl in the context of a rapid urbanization process in a booming economic region of southern China from 1979 to 2005. Three urban sprawl types are distinguished by analyzing overlaid urban area maps of two adjacent study years which originated from the interpretation of remote sensed images and vector land use maps. Landscape metrics are used to analyze the spatiotemporal pattern of urban sprawl for each study period. Study results show that urban areas have expanded dramatically, and the spatiotemporal landscape pattern configured by the three sprawl types changed obviously. The different sprawl type patterns in five study periods have transformed significantly, with their proportions altered both in terms of quantity and of location. The present research proves that urban sprawl quantification and pattern analysis can provide a clear perspective of the urbanization process during a long time period. Particularly, the present study on urban sprawl and sprawl patterns can be used by land use and urban planners. © Springer Science+Business Media B.V. 2012.
Tao W.,Guangzhou Institute of Geography
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2014
LIDAR(Light Detection And Ranging) is widely used in forestry applications to obtain information about tree density, composition, change, etc. An advantage of LIDAR is its ability to get this information in a 3D structure. However, the density of LIDAR data is low, the acquisition of LIDAR data is often very expensive, and it is difficult to be utilised in small areas. In this article we eavluate different methods by using multi-view to acquire high resolution images of the forest. Using the dense match method a dense point cloud can be generated. Our analysis shows that this method can provide a good alternative to using LIDAR in situations such as these.