Advanced Materials Research Vols. 518-523

Abstract: The soil erosion test was carried out for the Zhao He grassland on the northern foothills of Yin Shan Mountain by the use of a portable wind erosion tunnel developed by Inner Mongolia Agricultural University, the variation low of soil wind erosion rate with the different wind speed and different arrangement in pairs of different soil moisture content and different vegetation coverage was obtained and the data analysis indicates that the anti-wind erosion characteristics of ground surface is most satisfactory when the vegetation coverage is 40%, soil moisture content 9.3% and the height of vegetation 50cm. The result of this study may provide a certain reference date for the application of prevention and control technology of soil wind erosion and be of vital significance to the implementation of sustainable development of livestock husbandry.

Abstract: It was important to explore the law of water and sediment reduction of loess slope in different grass coverage for carrying out the grass construction and controlling slope erosion in the Loess Plateau. Using the tests of outside artificially runoff erosion simulation, in the condition of 5L/min of the scouring flows, we conducted a pilot study of sediment yield, erosion rates, and runoff sediment concentration in three different slope conditions of 15°, 20°, 25° and three grass coverage conditions of bare slope, 30%~40% and 70%~80%. The results showed that: the grass coverage has significantly influences on sediment yield, erosion rate and runoff sediment concentration of loess slope. Sediment yield of loess slope with grass coverage of 70 ~ 80% is less than 10% of that of bare slope. Under the same conditions of gradient and grass coverage, the sediment yield and runoff sediment concentration had a direct proportion with the scouring flow. Under the same conditions of gradient and scouring flows, the erosion rate and runoff sediment yield of loess slope are basically the same. Grass has a significant role in enhancing resistance to corrosion of soil and reducing erosion of loess slope.

Abstract: The lake basin morphology is closely related to the health level of the lake system function. It is the prerequisite and fundamental to evaluate whether the lake ecosystem and service function are healthy or not. According to historical documents, maps, water and sediment data from 1986 to 2010, the author evaluated the health of the lake basin morphology on the typical years by using the catastrophe progression method and by selecting 8 indicators which includes the exposed frequency of bottomland, hydrodynamic conditions and geometry form of the lake basin.The results showed that: ① The East Dongting Lake has a relatively good health status ( the average of membership grade is 0.7486), but with high fluctuations (0.6775 ~ 0.7965); then followed by South Dongting Lake, (0.7311); the worst is West Dongting Lake (0.7269) while it has a minimum fluctuation of health relative membership degree (0.7026 ~ 0.7487);② In the last 20 years, the health standard of the Morphological Structure of Dongting Lake Basin has shown an tendency of "firstly get worse then improved" . It had the lowest healthy membership grade in 1998(0.6912), and the highest value in 2004(0.7711), the values of the remaining typical years are in between. They constitute a sufficient support to claim that the implementation of "4350" project, and the construction and impounding of the Three Gorges reservoir dam are so effective in improving the lake basin morphology toward the more healthy developing direction.

Abstract: Investigations on macronutrients (K, Na, Ca, Mg and P) and micronutrients (Fe) in windy sand- and salt-resistant plant species such as Cymomorium can help us to get a better understand their behaviours of ecologically environment geochemistry in the Gobi arid desert ecosystem. This study presents our investigations on the concentrations of K, Na Ca, Mg, Fe and P in xerophilous, sabulicolous, superhalophilous Cymomorium from the oasis ecosystem in the Beishan-Tianshan Gobi arid desert, northwestern China. The mean concentrations of macronutrients (K, Na, Ca, Mg and P) in Cymomorium Songaricum Rupr. are, respectively, 1.29±0.29 % K, 2.45±1.08 % Na, 2966±2038 μg g–1 Ca, 2038±1746 μg g^–1 Mg and 1462±457 μg g^–1 P. Although the average concentrations of Fe concentrations (341±361 μg g^–1) is within the normal range of Fe in plant species, the maximum Fe concentrations (1400 μg g^-1) were detected in Cymomorium stemmed from the sandy lowland around the Shaquanzi iron mine of the Xinjiang Uygur Autonomous Region in China. It suggested that the indigenous species of Cymomorium might be one of the appropriate xerohalophyte species to restore the vegetation of the oasis, saline land use for agriculture or arid environments destroyed by mining activities in the dry land because it may have higher ability to accumulate K, Na, Ca, Mg, Fe and P from saline soils, and it belongs to the native salt-resistant plant species.

Abstract: Abstract. Dynamics of vegetation and soil properties responses to vegetation recovery in the selected 72 Karst desertification sites in Guizhou, China were studied. Six typical and representative vegetation types along a chronosequence of vegetation recovery (corn land, sparse grass, regeneration forest, shrub, grass and shrub, and native forest with 0, 3-5, 10-15, 20-30, 30-40, and >100 yrs, respectively) were selected for the study of the plant species, vegetation features as well as soil physical & chemical properties in order to assess interaction between soil properties and vegetation structure. It was found that vegetation species had dry-resistant characteristics because of their extensive exposure to the basement rocks and thinness soil. Grass community was always coarse grass, shrub was generally dominated by vines, thorn bushes and tree species were almost leather-like, single and mini-type leaf plants. Factor analysis showed that the 3 factors, soil fertility, pH and clay, explain 67.97 % of total variance among the 19 soil property parameters. Soil fertility changed significantly effects included the increasing of soil organic matter, total and available nitrogen, humic acid, CEC, fuvic acid, exchange Ca, porosity and total P but decreasing bulk density. This trend was followed by enhancing of bio-enrichment capacity along the chronosequence of vegetation recovering process. Soil pH had no significant correlation with the vegetation recovery stages because it was determined by soil forming process and characteristic of parent materials. The factor clay only decreased slightly in the recovery stages. Cluster analysis indicated that vegetation structure could develop within short time under anthropocentric interfering, but soil fertility only accumulated with annual litter decomposing. We can conclude that recovery of vegetation community structure proceeded restoration of soil function.

Abstract: Soil respiration as a major flux in the global carbon cycle plays an important role in regulating soil carbon pools. Global climatic changes including warming and a changing precipitation pattern could have a profound impact on soil respiration of terrestrial ecosystems, especially in arid and semiarid region where water is limited. We conducted a field experiment to simulate precipitation changes in a Mongolian pine plantation at Horqin sandy lands. The results indicated that, soil respiration was significantly affected by reduced rainfall treatment and water addition treatment in 9 experiment plots. Soil respiration rates in the water addition treatment plots increased about 40.7% to 166.4% and decreased about 34.0% to 70.0% in the reduced rainfall treatment plots. A model of the relationships between soil respiration and moisture with temperature was obtained by an empirical equation. Through operating the model, it was indicated that the highest soil respiration rate occurred at high soil water contents and intermediate soil temperatures in 9 plots. In the combined responses of soil respiration to soil temperature and soil moisture, soil temperature as a single independent variable explained only 29.9% of variance in soil respiration, and soil moisture was 71.3% of variance in soil respiration. It was concluded from our results that precipitation compared with soil temperature dominated more significantly the variability of ecosystem soil respiration in semiarid sandy lands.

Abstract: Through simulation research on hydraulic characteristics of precast interlocking concrete blocks, the stress condition, overall stability, the effect of filling gravels into the holes of the blocks in the water flow during the flood period and the resistance parameters of the blocks were studied, a comprehensive analysis on the mechanical stability and the scour-resisting characteristics of the blocks was made, and then the requirement and the safety degree of the gravel filling were given. The experiment shows that compared with the surface protection of the conventional dyke projects, besides convenience for manufacture at low cost, this new type of protective revetment has such merits as higher anti-shear stress, better stability and permeability as well as improving ecological environment in river course.

Abstract: The Renjiang River Catchment in Zunyi City, Guizhou Province of China was selected as the study area to research how to design and match the measures for rocky desertification control and ecosystem restoration. SPOT satellite image (resolution 2.5m), the topographic maps (1:10000), regionalism Map (1:50000), hydrogeological map were used to research under the 3S-Technology (GPS, RS, GIS) and software including ArcView, ArcGIS and Erdas. Many times of field survey and discussions with the local people and government were also carried out. Conclusions were drawn that: the design and match of the measures for the Renjiang River Catchment is scientific and rational; land use conditions, rocky desertification grades, land suitability assessment and prediction of the cultivated land demanded are very important for the design and matching of the measures for the rocky desertification control; a comprehensive idea for each small catchement how to select and design individual measure and how to match the measures together to achieve the best effect of rocky desertification control is also important. Finally, suggestions are given for the karst rocky desertification areas that land use conditions, rocky desertification grades, land suitability assessment and prediction of the cultivated land demanded should be fully considered in the process of designing and matching the measures; the land use should be matched with the rocky desertification and should support the scale of measured designed; measures can be implemented only when these measures do not threat the basic cultivated land demand; the land suitability should also support the area of the measures designed.

Abstract: Suitability evaluation plays a determining and crucial role in the preliminary and terminal stages of the land reclamation, which is carried out to prove the suitability of land reclamation from the perspective of technology, society and ec onomy based on scientific technology, economic technology, Informatics, Prognostics and Mathematical statistics. Besides soil, climate, topography, water, farming practices, phreatic level also matters a lot for the suitability evaluation. Therefore, the present paper studies the land reclamation suitability in the plain mining areas with high phreatic water level, which will be supportive to determine the reclamation direction and allocate the land resources in reclamation areas.

Abstract: Under the influence of the properties of underlying surface, the wind-sand flow structure near the ground is different when the sandstorm occurs in different areas. In this paper, in order to explore the structure features of the wind-sand flow near the ground during a sandstorm in desertification grassland, Zhao He observation station at Inner Mongolia, China, in desertification grassland has been selected as an example. According to data measured by anemometer and sand collector，a comparative analysis on the relative sediment concentrations for different height in eight directions during the sandstorm on April 29-30，2011, and study the pattern of wind-sand flow structure have been done. The result shows that the first-rank curve fitting of wind-sand flow structure is exponential function under the northwest (main direction of the sandstorm), and the sediment discharge were increased with the height increase. The wind-drift sand flows are mainly suspension in prevailing wind direction. In the southeast, the opposite to the prevailing wind direction, the first-rank curve fitting of wind-sand flow structure is power function that showed sediment discharge were decreased with height increase, and saltation is the main wind-drift sand flows movement pathway. In the rest directions, weak correlations between sediment discharge and height during a sandstorm have been found. The closer directions to the prevailing wind direction, the more relative sediment discharge in the elevations above 30-35cm