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.
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.
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.
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.
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.