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Wang C.,Jiangsu University | Pei X.,State Key Laboratory Cultivation Base of Geographical Environment Evolution Jiangsu Province | Yue S.,Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application | Wen Y.,Nanjing Normal University
Wetlands | Year: 2016

Vegetation and soil are important factors in coastal wetland landscape evolution. This paper investigates the relationship between the aboveground biomass of Spartina alterniflora and soil factors of varying settling ages in Yancheng, China using correlation analysis and principal component analysis. The results indicate the following: (1) Soil factors varied significantly with different settlement ages of S. alterniflora that expanded toward the land and sea. Soil bulk density decreased with settlement age and was lowest for growth period IV (10 – 16 year old sites) whereas an opposite trend was shown for soil moisture. Soil salinity and soil nutrients were highest for growth period III (6 – 10 year old sites) (2) Principal component analysis demonstrated that soil bulk density, moisture and salinity are the main soil factors that drive landscape evolution in S. alterniflora marshes. (3) There was a significant positive correlation between S. alterniflora biomass and the organic matter and bulk density of soil (p < 0.05). Results showed that the invasion and settlement of S. alterniflora in the coastal wetland of Yancheng are changing the physical and chemical properties of the coastal wetland soil. This study has contributed to an understanding of wetland succession in the coastal landscape. © 2016 Society of Wetland Scientists Source


Duan P.,Yunnan Normal University | Li J.,Yunnan Normal University | Lv H.Y.,Nanjing Normal University | Lv H.Y.,State Key Laboratory Cultivation Base of Geographical Environment Evolution Jiangsu Province | Lv H.Y.,Jiangsu Center for Collaborative Innovation in Geographical
MATEC Web of Conferences | Year: 2016

In the Kriging interpolation method, different theory models of variation function are selected and fitted. There are many common variation function models, such as spherical model, index model, Gaussian model and so on. As these variation function models are non-linear, non-linear model are converted to linear model when these variation function models are solved. Different variation function models with different conversion methods are lack of generality in the process of Kriging interpolation. Particle swarm optimization algorithm with the advantages of global optimal solution can be directly used to solve non-linear fitting equation. In this paper, variation function model based on particle swarm optimization algorithm is fitted. Experiment shows that it is appropriate for fitting variable function based particle swarm optimization algorithm. © Owned by the authors, published by EDP Sciences, 2016. Source


Chen M.,Jiangsu Center For Collab Innovation In Geographical Information Resource Development | Chen M.,State Key Laboratory Cultivation Base of Geographical Environment Evolution Jiangsu Province | Chen M.,Chinese University of Hong Kong | Chen M.,Nanjing Normal University | And 4 more authors.
Applied Geography | Year: 2015

Increasing research has been conducted to improve navigation services for the blind when they are moving through an outdoor space. This article aims to propose a formal modeling approach helps facilitate decision making about navigation pathways. The proposed data model is based on an objective orientation idea. City features, such as street features, buildings and environmental areas, are organized as a series of function objects that meet the various needs of the blind. They are linked by paths with obstacles and irregular surface objects. A complex function object is composed of several inner function objects and paths; thus, it can reflect the spatial layout at various levels. Detailed semantic content can be added into the objects as an extension that enhances the representation and facilitates spatial learning. The geometric shapes of the proposed objects and their topological information are also recorded for local navigation and comprehensive path planning. To examine the usability of the data model, a prototype system was developed using the Chinese university of Hong Kong as a study area, and test cases are illustrated for a typical designed scenario. © 2015 Elsevier Ltd. Source


Li F.,State Key Laboratory Cultivation Base of Geographical Environment Evolution Jiangsu Province | Li F.,Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application | Tang G.,State Key Laboratory Cultivation Base of Geographical Environment Evolution Jiangsu Province | Tang G.,Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application | And 3 more authors.
Frontiers of Earth Science | Year: 2015

A simulated loess watershed, where the loess material and relief properly represent the true loess surface, is adopted to investigate the variation in slope spectrum with loess watershed evolution. The evolution of the simulated loess watershed was driven by the exogenetic force of artificial rainfall. For a period of three months, twenty artificial rainfall events with different intensities and durations were carried out. In the process, nine DEM data sets, each with 10 mm grid resolution, were established by the method of close-range photogrammetry. The slope spectra were then extracted from these DEMs. Subsequent series of carefully designed quantitative analyses indicated a strong relationship between the slope spectrum and the evolution of the simulated loess watershed. Quantitative indices of the slope spectrum varied regularly following the evolution of the simulated loess watershed. Mean slope, slope spectrum information entropy (H), terrain driving force (Td), Mean patch area (AREA_MN), Contagion Index (CONTAG), and Patch Cohesion Index (COHESION) kept increasing following the evolution of the simulated watershed, while skewness (S), Perimeter-Area Fractal Dimension (PAFRAC), and Interspersion and Juxtaposition Index (IJI) represented an opposite trend. All the indices changed actively in the early and active development periods, but slowly in the stable development periods. These experimental results indicate that the time series of slope spectra was able to effectively depict the slope distribution of the simulated loess watershed, thus presenting a potential method for modeling loess landforms. © 2015 Higher Education Press and Springer-Verlag Berlin Heidelberg Source


Zhao W.,Nanjing Normal University | Zhao W.,Nanjing University of Technology | Zhang J.,Nanjing Normal University | Zhang J.,State Key Laboratory Cultivation Base of Geographical Environment Evolution Jiangsu Province | And 6 more authors.
Journal of Soils and Sediments | Year: 2016

Purpose: Input of N as NH4 + is known to stimulate nitrification and to enhance the risk of N losses through NO3 − leaching in humid subtropical soils. However, the mechanisms responsible for this stimulation effect have not been fully addressed. Materials and methods: In this study, an acid subtropical forest soil amended with urea at rates of 0, 20, 50, 100 mg N kg−1 was pre-incubated at 25 °C and 60 % water-holding capacity (WHC) for 60 days. Gross N transformation rates were then measured using a 15N tracing methodology. Results and discussion: Gross rates of mineralization and nitrification of NH4 +-N increased (P < 0.05), while gross rate of NO3 − immobilization significantly decreased with increasing N input rates (P < 0.001). A significant relationship was established between the gross nitrification rate of NH4 + and the gross mineralization rate (R2 = 0.991, P < 0.01), so was between net nitrification rate of NH4 + and the net mineralization rate (R2 = 0.973, P < 0.05). Conclusions: Stimulation effect of N input on the gross rate of nitrification of NH4 +-N in the acid soil, partially, resulted from stimulation effect of N input on organic N mineralization, which provides pH-favorable microsites for the nitrification of NH4 + in acid soils (De Boer et al., Soil Biol Biochem 20:845–850, 1988; Prosser, Advan Microb Physiol 30:125–181, 1989). The stimulated gross nitrification rate with the decreased gross NO3 − immobilization rate under the elevated N inputs could lead to accumulation of NO3 − and to enhance the risk of NO3 − loss from humid forest soils. © 2016 Springer-Verlag Berlin Heidelberg Source

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