Wang Yanglin

Using impervious surfaces to detect urban expansion in Beijing of China in 2000s

The change of impervious surface area (ISA) can effectively reveal the gradual process of urbanization and act as a key index for monitoring urban expansion. Experiencing rapid growth of the built environment in the 2000s, urban expansion of Beijing has not been fully characterized through ISA. In this study, Landsat TM images of Beijing in 2001 and 2009 were obtained, and the eight-year urban expansion process in Beijing was analyzed using the ISA extracted by means of the vegetation-imperious surface-soil (V-I-S) model. From the spatial variation in ISA, the ring structure of urban expansion in Beijing was significant during the study period, with decreasing urban density from the city center to the periphery. In the ring road analysis, the most dramatic changes of ISA were found between the fifth ring and the sixth ring. This area has experienced the most new residential development, and is currently the main source of urban expansion. The typical profile lines revealed the directional characteristics of urban expansion. The east-west profile was the most urbanized axes in Beijing, while ISA change in the east-north profile was more significant than in the other five profiles. Moreover, the transition matrix of ISA levels revealed an increase in urban density in the low density built areas; the Moran′s I index showed a clear expansion of the central urban area, which spread contiguously; and the standard deviational ellipse indicated the northeast was the dominant direction of urban expansion. These findings can provide important spatial control guidelines in the next round of national economic and social development planning, overall urban and rural planning, and land use planning.

A mathematical model of soil moisture spatial distribution on the hill slopes of the Loess Plateau

Based on important factors that affect soil moisture spatial distribution, such as the slope gradients, land use, vegetation cover, and surface water diffusion characteristics together with field measurements of soil moisture data obtained from the surface soil under different land use structures, a soil moisture spatial distribution model was established. The diffusion degree coefficient of surface water for different vegetations was estimated from soil moisture values obtained from field measurements. The model can be solved using the finite unit method. The soil moisture spatial distribution on the hill slopes in the Loess Plateau were simulated by the model. A comparison of the simulated values with measurement data shows that the model is a good fit.Based on important factors that affect soil moisture spatial distribution, such as the slope gradients, land use, vegetation cover, and surface water diffusion characteristics together with field measurements of soil moisture data obtained from the surface soil under different land use structures, a soil moisture spatial distribution model was established. The diffusion degree coefficient of surface water for different vegetations was estimated from soil moisture values obtained from field measurements. The model can be solved using the finite unit method. The soil moisture spatial distribution on the hill slopes in the Loess Plateau were simulated by the model. A comparison of the simulated values with measurement data shows that the model is a good fit.

Zoning by Functions of Small-Scale Forest Ecosystems: A Case Study of Hui-Sun Forest Station in Taiwan Province, China

To optimize the spatial structure of an ecosystem, a forest landscape was selected as a research object. Based on the theory of structure and functions of landscape ecology, combined with the analysis of the characteristics of the inner structure in an ecosystem, this paper proposes to establish certain procedures to regulate the spatial structure of this forest landscape and construct a landscape pattern of forest ecosystem functions. Considering the functions of biologic production, environmental services, and cultural support in forest ecosystems, forest landscape zones should consist of areas of forest production, research, experimentation, recreation, and conservation to add value to the forest ecosystem, enhance its functions, and then identify the relevant environmental factors according to the environment featured in the research area. Based on the methods of landscape ecology and ecological planning, this paper develops a zoning project of ecosystem functions suitable for various environments. For this research, the Hui-Sun forest station in Taiwan Province, China was selected to be the experimental area for studying the feasibility of developing a zoning project of forest ecosystem services and the suitability of optimizing the spatial structures of the services.