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Cheng W.,Beijing Forestry University | Zhang Y.,Beijing Forestry University | Zhang Y.,Yanchi Research Station | Wu X.,Beijing Forestry University | And 4 more authors.
2011 International Conference on Remote Sensing, Environment and Transportation Engineering, RSETE 2011 - Proceedings | Year: 2011

In order to rapidly and accurately extract the feature information of sandy area in the north of Yanchi County, the QuickBird high-resolution remote sensing images were selected as data source. The choice of the best segmentation scale was analysed in depth. The way of object-oriented supervised classification and object-oriented classification by rules were used into information extraction. The results show objectoriented image feature classification can quickly extract characteristic information of sandy area in the north of Yanchi County by choosing the appropriate scale image segmentation and rules which is determined by the different characteristics of extraction information. © 2011 IEEE.

Wei B.,Beijing Forestry University | Ding G.-D.,Beijing Forestry University | Ding G.-D.,Yanchi Research Station | Wu B.,Beijing Forestry University | And 7 more authors.
Beijing Linye Daxue Xuebao/Journal of Beijing Forestry University | Year: 2013

Windbreak mechanism under different shrub cover conditions was quantitatively studied by carrying out a field investigation in southwestern marginal zone of the Mu Us Sandy Land, northwestern China. Artemisia ordosica and Salix psammophila shrub land were taken as the object of this study. Bare sand was set as control and the wind velocities at 0.1, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 m height upon research grounds were recorded. By doing statistical analysis of wind velocity measurements, drawing wind profile, calculating the wind profile equation, boundary layer thickness, aerodynamic roughness, we got the conclusion that both A. ordosica and S. psammophila shrub land decreased wind velocity of boundary layer much more significantly than bare land, and this effect decreased with wind velocity increasing. Aerodynamic roughness of shrub land decreased logarithmically with wind velocity increasing. When wind velocity was high, boundary layer displacement thickness would reflect the decrease of wind velocity at observation height more realistically than aerodynamic roughness. Analyzing from the air momentum, the loss of air momentum on the surface covered with vegetation was relatively stable. While the loss of air momentum on bare sand would decrease as wind velocity increasing.

Gao G.,Beijing Forestry University | Gao G.,Yanchi Research Station | Ding G.,Beijing Forestry University | Ding G.,Yanchi Research Station | And 6 more authors.
Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and Engineering | Year: 2014

We constructed an aeolian soil database in the Mu Us Desert. Soil particle size distribution(PSD)was measured with a laser diffraction technique, and the volume-based fractal dimensions were calculated following the standards of Chinese(DCHN), Soviet(DSU), American(DUS), and International(DINT)soil PSC systems. The results indicated that(1)The predominant soil particle size was distributed within the sand classification, which accounted for more than 90%of the total volume; Clay and silt particle contents were much less prevalent. The order of volume-based fractal dimensions was as follow: DSU, DCHN, DINT, and DUS. (2)Significant linear correlations occurred among DCHN, DUS, DINT, and clay, silt and sand particle contents(P<0.01), respectively, with the exception of any significant correlations between DSU and silt and sand particle contents(P<0.05), which showed a poor linear relationship. (3)There were significant positive correlation among DCHN, DINT and DUS(P<0.01), where there were poor correlations between DSU and other fractal dimensions. The linear regression analysis realized mutual transformation among DCHN, DUS and DINT. Taking into consideration soil PSD data, D values, and the observed correlations, we highly recommend that the American soil PSC system should be the optional system for calculating volume-based fractal dimensions of soil PSD. ©, 2014, The Editorial Board of Journal of Basic Science and Engineering. All right reserved.

Deng J.-F.,Beijing Forestry University | Ding G.-D.,Beijing Forestry University | Ding G.-D.,Yanchi Research Station | Wu B.,Beijing Forestry University | And 6 more authors.
Beijing Linye Daxue Xuebao/Journal of Beijing Forestry University | Year: 2014

A study of hydrological effects of litter layer and soil layer was carried out in two artificial forest stands (Populus bolleana and Pinus sylvestris var. mongolica) and one natural forest stand (Hedysarum scoparium) in Yanchi County, Ningxia of northwestern China. Its hydrological function of litter and soil was evaluated quantitatively through investigating standard spots, determining soil physical characteristics and water-holding capacity, and experimenting on soil infiltration, determining litter and soil water-holding capacity. The results showed that: 1) the litter total storage capacity of P. sylvestris var. mongolica was the largest, up to 7.86 t/hm2; P. sylvestris var. mongolica stand had both the maximum water capacity and available water capacity, which were 23.73 and 18.26 t/hm2, equivalent to water depth of 2.37 and 1.83 mm separately. 2) The P. sylvestris var. mongolica stand had strong soil water-holding capacity and the maximum of which was 349.12 t/hm2, equivalent to 34.91 mm water depth. The available soil water-holding capacity of P. sylvestris var. mongolica stand was 85.75 t/hm2, which was 3.24 times of H. scoparium stand, equivalent to 8.58 mm water depth. 3) Power function model can better reflect both water absorption speed of ground cover and its immersing time, and soil infiltrating rate and infiltrating time under different rainfall conditions, which had high correlation coefficient. 4) Using Philip infiltration model fitting the soil infiltration process (1 m deep soil), soil infiltration characteristics of different forest stands were obtained.

Zhang Y.-Q.,Beijing Forestry University | Zhang Y.-Q.,Yanchi Research Station | Liu J.-B.,Beijing Forestry University | Jia X.,Beijing Forestry University | And 3 more authors.
Polish Journal of Environmental Studies | Year: 2013

The rate and factors determining changes in the soil carbon pool after afforestation are still poorly understood, especially in arid and semiarid areas. This paper provides a review of the influence effect of afforestation on soil organic carbon (SOC) stocks based on a meta-analysis of 37 publications (including a total of 116 observations in the past 10 years), with the aim of exploring the major factors that can affect changes in soil carbon stocks after afforestation in arid and semiarid areas. This meta-analysis, which was based on a mixed linear model, indicates that the main factors that contribute to SOC accumulation after afforestation are previous land use, plantation age, mean annual precipitation, and mean annual temperature. It suggests that bare areas are the most suitable areas for afforestation, and that regions with precipitation of 250-400 mm and mean annual temperatures of 7.5-15°C have a greater impact on an area's capacity to accumulate SOC following afforestation. It shows that more SOC can be accumulated with the increase of plantation age. However, it also shows that plant species significantly affect SOC accumulation. This research will contribute to the development of policies of environment management and the models concerned with quantifying amounts of soil carbon sequestered by afforestation in these areas.

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