Characterizing changes in the soil particle-size distributions (PSD) are a major issue in environmental research because it has a great impact on soil properties, soil management, and desertification. To date, the use of soil volume fractal dimension (D) is a feasible approach to describe PSD, and its calculation is mainly dependent on subdivisions of clay, silt, sand fractions as well as different soil particle-size classification (PSC) systems. But few studies have developed appropriate research works on how PSC systems affect the calculations of D. Therefore, in this study, topsoil (0–5 cm) across nine forest density gradients of Pinus sylvestris var. mongolica plantations (MPPs) ranging from 900–2700 trees ha^–1 were selected in the Mu Us sandy land, China. The D of soil was calculated by measuring soil PSD through fractal model and laser diffraction technique. The experimental results showed that: (1) The predominant PSD was distributed within the sand classification followed by clay and silt particle contents, which were far less prevalent in the study area. The general order of D values (Ds) was USDA (1993) > ISO14688 (2002) > ISSS (1929) > Katschinski (1957) > China (1987) > Blott & Pye (2012) PSC systems. (2) Ds were significantly positively related to the contents of clay and silt, and Ds were significantly negatively to the sand content. Ds were susceptible to the MPPs establishment and forest densities. (3) Ds of six PSC systems were significantly positive correlated, which indicated that they not only have difference, but also have close connection. (4) According to the fractal model and descriptions of soil fractions under different PSC systems, refining scales of clay and sand fractions could increase Ds, while the refining scale of silt fraction could decrease Ds. From the conclusions above, it is highly recommended that USDA (1993) and Blott & Pye (2012) PSC systems be used as reliable and practical PSC systems for describing and calculating D of soil PSD.

This paper reviews the emergence of the idea of ecological city; expounds the concept, connotation, and characteristics of ecological city; and summarizes related practical research. The purpose of this paper is to provide suggestions for the future construction of ecological city through the study of ecological city theory and practice. This paper aims to explore the driving factor and construction of an ecological city, strengthen the combination of theory and practice and the systematization and integrity of theory and method, and create a well-rounded atmosphere of ecological city.

This paper constructs an evaluation index system that assesses the ecological civilization construction level of Shenyang from 2011 to 2016 with the help of the analytical hierarchy process and the Delphi method. Although the results did show any apparent increase in the ecological civilization construction level of Shenyang, the city demonstrated a generally stable natural ecological level. The growing resource allocation and social civilization of the city were also accompanied by a decline in its population structure. Shenyang also demonstrated an initial decrease in its environmental guarantee that was immediately followed by an increase. However, the opposite trend was observed for its economic development.