Kuzyakov Y.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research |
Kuzyakov Y.,University of Gottingen |
Xu X.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
New Phytologist | Year: 2013
Demand of all living organisms on the same nutrients forms the basis for interspecific competition between plants and microorganisms in soils. This competition is especially strong in the rhizosphere. To evaluate competitive and mutualistic interactions between plants and microorganisms and to analyse ecological consequences of these interactions, we analysed 424 data pairs from 41 15N-labelling studies that investigated 15N redistribution between roots and microorganisms. Calculated Michaelis-Menten kinetics based on Km (Michaelis constant) and Vmax (maximum uptake capacity) values from 77 studies on the uptake of nitrate, ammonia, and amino acids by roots and microorganisms clearly showed that, shortly after nitrogen (N) mobilization from soil organic matter and litter, microorganisms take up most N. Lower Km values of microorganisms suggest that they are especially efficient at low N concentrations, but can also acquire more N at higher N concentrations (Vmax) compared with roots. Because of the unidirectional flow of nutrients from soil to roots, plants are the winners for N acquisition in the long run. Therefore, despite strong competition between roots and microorganisms for N, a temporal niche differentiation reflecting their generation times leads to mutualistic relationships in the rhizosphere. This temporal niche differentiation is highly relevant ecologically because it: protects ecosystems from N losses by leaching during periods of slow or no root uptake; continuously provides roots with available N according to plant demand; and contributes to the evolutionary development of mutualistic interactions between roots and microorganisms. © 2013 New Phytologist Trust.
Song W.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
Habitat International | Year: 2014
For more than three decades, China has experienced large-scale expansion of construction land (i.e., land used for building structures and infrastructure) and a rapid loss of cultivated land, especially in metropolises. The present study assessed cultivated land loss due to construction occupation (i.e., the expansion of construction land) in Beijing. The effects of economic growth on cultivated land losses were also examined using a decoupling approach. It was found that the expansion of construction land in Beijing occupied an additional 845.2km2, 304.5km2 and 869.0km2 of cultivated land during the periods 1986-1995, 1995-2000 and 2000-2005 respectively. During 1986-1995, cultivated land was mainly taken over by the expansion of urban areas, whereas during 1995-2000 it was mainly replaced by the expansion of rural settlements, and, during 2000-2005, by uses in the "other construction" land use category (e.g., roads, railways, or industrial facilities located apart from urban areas or rural settlements). Beijing's economy and population growth were prominently decoupled from cultivated land losses during 1995-2000, but became negative decoupled during 2000-2005. © 2014 Elsevier Ltd.
Huang H.Q.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
Water Resources Research | Year: 2010
Due to a lack of sufficient theoretical relations, equations for bed load transport in alluvial channel flow have been developed using a variety of empirical assumptions. A linear relationship exhibited in the complex interactions among the three essential components of a river (channel geometry, bed load transport and flow resistance) has led this study to develop a more accurate form of the Meyer-Peter and Mller (1948, hereafter MPM) relationship, one of the world's most widely used bed load transport equations. This study demonstrates that the application of linearity theory can significantly improve its performance. On the basis of the dataset originally used by MPM, it is shown that the applicable form of the Manning-Strickler flow resistance relationship can be very satisfactorily determined. The MPM equation is consequently found to be expressible more accurately as φ = 6[ητb*-0. 047]5/3, where φ, η and τ*b are the normalized, dimensionless bed load transport rate, bed-form correction, and flow-strength parameters, respectively. Copyright 2010 by the American Geophysical Union.
Sang Y.-F.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
Water Resources Management | Year: 2012
Discrete wavelet transform (DWT) is commonly used for wavelet threshold de-noising, wavelet decomposition, wavelet aided hydrologic series simulation and prediction, as well as many other hydrologic time series analyses. However, its effectiveness in practice is influenced by many key factors. In this paper the "reference energy function" was firstly established by operating Monte-Carlo simulation to diverse noise types; then, energy function of hydrologic series was compared with the reference energy function, and four key issues on discrete wavelet decomposition were studied and the methods for solving them were proposed, namely wavelet choice, decomposition level choice, wavelet threshold de-noising and significance testing of DWT, based on which a step-by-step guide to discrete wavelet decomposition of hydrologic series was provided finally. The specific guide is described as: choose appropriate wavelet from the recommended wavelets and according to the statistical characters relations among original series, de-noised series and removed noise; choose proper decomposition levels by analyzing the difference between energy function of the analyzed series and reference energy function; then, use the chosen wavelet and decomposition level, estimate threshold according to series' complexity and set the same threshold under each level, and use the mid-thresholding rule to remove noise; finally, conduct significance testing of DWT by comparing energy function of the de-noised series with the reference energy function. Analyses of both synthetic and observed series indicated the better performance and easier operability of the proposed guide compared with those methods used presently. Following the guide step by step, noise and different deterministic components in hydrologic series can be accurately separated, and uncertainty can also be quantitatively estimated, thus the discrete wavelet decomposition result of series can be improved. © 2012 Springer Science+Business Media B.V.
Oduor A.M.O.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
New Phytologist | Year: 2013
Strong competition from invasive plant species often leads to declines in abundances and may, in certain cases, cause localized extinctions of native plant species. Nevertheless, studies have shown that certain populations of native plant species can co-exist with invasive plant species, suggesting the possibility of adaptive evolutionary responses of those populations to the invasive plants. Empirical inference of evolutionary responses of the native plant species to invasive plants has involved experiments comparing two conspecific groups of native plants for differences in expression of growth/reproductive traits: populations that have experienced competition from the invasive plant species (i.e. experienced natives) versus populations with no known history of interactions with the invasive plant species (i.e. naïve natives). Here, I employ a meta-analysis to obtain a general pattern of inferred evolutionary responses of native plant species from 53 such studies. In general, the experienced natives had significantly higher growth/reproductive performances than naïve natives, when grown with or without competition from invasive plants. While the current results indicate that certain populations of native plant species could potentially adapt evolutionarily to invasive plant species, the ecological and evolutionary mechanisms that probably underlie such evolutionary responses remain unexplored and should be the focus of future studies. © 2013 New Phytologist Trust.
Bao C.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research |
Fang C.-L.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
Renewable and Sustainable Energy Reviews | Year: 2013
With rapid urbanization and industrialization, China has become both the largest energy consumer and CO2 emitting country in the world. As a clean and low-carbon energy source, renewable energy is a good choice to substitute for the exhausted fossil energy. The Chinese central and local governments have made a series of policies and optimistic plans to promote a rapid development of renewable energies. China′s renewable energy development has become a key to the sustainable development of socio-economic system. Unlike most of the current studies which mainly identified the challenges regarding policies and technologies around renewable energy or performed specific analyses for a certain kind of renewable energy, this paper summarizes the spatial disparity and consistency among the major renewable energies, coal resources, energy consumption and its major influencing factors in China, and reviews the positive and negative environmental impacts of major renewable energies. Based on the geographical and environmental perspectives, this paper recommends that the Chinese government: constructs the national energy production bases according to the resource distribution; integrates different energies on the basis of their natural features and spatial consistency; adjusts the overall layout of socio-economic development consistent with renewable energies; and promotes a moderate renewable energy development to maximize the environmental benefits. © 2013 Elsevier Ltd.
Long H.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
Journal of Geographical Sciences | Year: 2014
The implementation of new type industrialization and urbanization and agricultural modernization strategies lacks of a major hand grip and spatial supporting platform, due to long-term existed "dual-track" structure of rural-urban development in China as well as unstable rural development institution and mechanism. It is necessary to restructure rural production, living and ecological space by carrying out land consolidation, so as to establish a new platform for building new countryside and realizing urban-rural integration development in China. This paper develops the concept and connotation of rural spatial restructuring. Basing on the effects analysis of industrialization and urbanization on rural production, living and ecological space, the mechanism of pushing forward rural spatial restructuring by carrying out land consolidation is probed. A conceptualization of the models of rural production, living and ecological spatial restructuring is analyzed combining with agricultural land consolidation, hollowed villages consolidation and industrial and mining land consolidation. Finally, the author argues that a "bottom-up" restructuring strategy accompanied by a few "top-down" elements is helpful for smoothly pushing forward rural spatial restructuring in China. In addition, the optimization and restructuring of rural production, living and ecological space will rely on the innovations of regional engineering technology, policy and mechanism, and mode of rural land consolidation, and more attentions should be paid to rural space, the foundation base and platform for realizing urban-rural integration development. © 2014 Science Press and Springer-Verlag Berlin Heidelberg.
Long H.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
Acta Geographica Sinica | Year: 2013
Currently, the implementation of new type industrialization, new type urbanization and agricultural modernization strategy lacks of a major hand grip and spatial sustain platform, due to long-term existed "dual-track" structure of rural-urban development in China as well as unstable rural development institution and mechanism and backward rural and agricultural infrastructures, which greatly affects the advancement of urban-rural integration development. It is necessary to restructure rural production, living and ecological space by carrying out land consolidation, so as to establish a new platform for building new countryside and realize urban-rural integration development in China. This paper develops the concept and connotation of rural spatial restructuring, i.e., an optimization and adjustment even utterly changing process of rural production, living and ecological space accompanied by rural socio-economic structure reshaping under the pressure of rapid industrialization and urbanization. The connotations of rural spatial restructuring involve three aspects of assembling industrial development, centralizing farmers' living and intensive resources utilization. Based on the effects analysis of industrialization and urbanization on rural production, living and ecological space, this paper also probes the mechanism which push forward rural spatial restructuring by carrying out land consolidation, an important approach to supplying cultivated land, revitalizing the stock land, optimizing rural-urban land, utilizing land intensively, and increasing land productivity. A conceptualization of the models of rural production, living and ecological environment spatial restructuring is analyzed in combination with agricultural land consolidation, hollowed villages consolidation and industrial and mining land consolidation. Finally, the author argues that a "bottom-up" restructuring strategy accompanied by a few "top-down" elements is helpful for smoothly pushing forward current rural spatial restructuring in China. The optimization and restructuring of rural intensive and high-efficient production space, suitable living space with amenity and ecological space with beautiful mountain and clean water will rely on the innovation of regional engineering technology, policy mechanism and mode of rural land consolidation, and more attentions should be paid to rural space, the foundation base and platform for realizing urban-rural integration development.
Li Y.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
Environmental Geochemistry and Health | Year: 2013
A field survey of mercury pollution in environmental media and human hair samples obtained from residents living in the area surrounding the Chatian mercury mine (CMM) of southwestern China was conducted to evaluate the health risks of mercury to local residents. The results showed that mine waste, and tailings in particular, contained high levels of mercury and that the maximum mercury concentration was 88. 50 μg g-1. Elevated mercury levels were also found in local surface water, paddy soil, and paddy grain, which may cause severe health problems. The mercury concentration of hair samples from the inhabitants of the CMM exceeded 1. 0 μg g-1, which is the limit recommended by the US EPA. Mercury concentrations in paddy soil were positively correlated with mercury concentrations in paddy roots, stalks, and paddy grains, which suggested that paddy soil was the major source of mercury in paddy plant tissue. The average daily dose (ADD) of mercury for local adults and preschool children via oral exposure reached 0. 241 and 0. 624 μg kg-1 body weight per day, respectively, which is approaching or exceeds the provisional tolerable daily intake. Among the three oral exposure routes, the greatest contributor to the ADD of mercury was the ingestion of rice grain. Open-stacked mine tailings have resulted in heavy mercury contamination in the surrounding soil, and the depth of appreciable soil mercury concentrations exceeded 100 cm. © 2012 Springer Science+Business Media B.V.
Ge Y.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
International Journal of Applied Earth Observation and Geoinformation | Year: 2013
Outputs of soft classification inherently contain uncertainty. As an input for the sub-pixel mapping (SPM) method, the uncertainty is propagated to SPM result especially the boundary region between classes. Therefore, reducing the uncertainty within the outputs of soft classification is worth exploring. This paper firstly utilizes multiple-point simulation (MPS) through training images for characterizing the spatial structural properties of a surface object/class. Consequently, MPS results are used to increase the accuracy of the fraction image of the surface object/class. The improved fraction image then inputs to the SPM method for producing the land cover map with finer spatial resolution. In order to validate the proposed method, a remotely sensed image from Landsat TM 30 m over the Qianyanzhou red earth hill region in China is used. This experimental study not only compares the results from SPM with improved fraction images with MPS and results from SPM with original fraction images, but also investigates the performances of different soft classifiers. It has been demonstrated that this proposed method is an effective way to reduce the uncertainty in outputs of different soft classification, increase the recognition accuracies of boundary regions and thus increase the accuracies of SPM simulated images. © 2012 Elsevier B.V.