Advanced Materials Research Vols. 726-731

Abstract: Pre-warning system of water resources security is a multi-level and complex system made of many factors. By analyzing current situation of water resources security pre-warning, operating mechanism of water resources security pre-warning system is put forward, Logic, time and knowledge related to operating mechanism are discussed. For pre-warning threshold decision is one of key technology in water resources security pre-warning, warning threshold decision and warning degree classification of water resources security pre-warning are set forth. These methods are systematic method, control chart method, synthetic judgement method, catastrophism method and expert decision method. Adopting the water resources security pre-warning system, situation can be analyzed and predicted promptly and effectively.

Abstract: Desertification has caused great harms to the ecological environment and socio-economic. Through many years test in Xinjiang desert area, some useful modes of desert governance can be implemented: (1) making use of advanced water-saving irrigation technology; (2) combining reasonable cropping patterns with higher economic value plants like arbors, shrubs and medicinal herbs planted in the desert, which not only plays the roles of windbreak and sand fixing, but also can gain some economic, ecological and social benefits.

Abstract: Whether the ecologically fragile areas can avoid weakness and enhance strong points and take advantages of their resources and carry on the reasonable development, it is related to the success or failure of the regional economic and social sustainable development strategy. Yellow River Delta as typical ecological fragile areas in China, the development of ecological and circulatory agriculture has strategic significance for the area towards the road of sustainable development. For the problem about Yellow River Delta develop ecological and circulatory agriculture, such as fragile ecological conditions, water shortages , serious environmental pollution, ecological technology relatively backward, low cultural quality of the agricultural labor force and weak support policies, we must take some countermeasures like development of rural education, promotion of ecotechnological progress, improvement of the agroecological environment , the comprehensive development and so on.

Abstract: It was proved that karst processing during groundwater cycle is one of carbon sinks to the atmosphere CO₂. To understand the carbon transfer path among the three phases of air, carbonate rocks and karst groundwater in epigenic karst system is very important for mechanic studies of karst carbon sink. There are 8 carbon stable isotope sample sites, including 5 groundwater sites and 3 gaseous CO₂ sites in Banzhai river catchment. The total 41 samples, including 38 karst water samples and 3 CO₂ samples are acquired in a whole hydrological year of 2010. 4 couples CO₂ partial pressure including free air and soil air are tested in site. Based on analysis the carbon stable isotope and CO₂ partial pressure data above, it is found that the mostly carbon in free air and karst water is from soil air. The carbon transfer path in epigenic karst system can be divided into 4 steps: 1 the photosynthesis of vegetation take CO₂ from free air; 2 the respiration of plant roots and decomposition of humic substance release CO₂ to soil layer; 3 the gaseous CO₂ is transfer to liquid HCO₃^- negion by karst process during the water cycle; 4 the bicarbonate in groundwater move to river or ocean fellow the groundwater flow. The forest and soil takes a booster pump action increasing the CO₂ partial pressure from free air to soil and it is very important in karst process.

Abstract: To reveal the relationship between chlorophyll fluorescence characteristics of desert plants and soil moisture in the hinterland of the Taklimakan Desert in south Xinjiang of China, Haloxylon ammodendron and Nitraria sibirica were selected and the chlorophyll fluorescence parameters under drought stress was determined. The results were shown that: (1) The maximum light quantum yield Fv/Fm value decreased with the decline of soil moisture content. (2) Fv/Fm values of Haloxylon ammodendron and Nitraria sibirica had changed significantly; when the Fv/Fm value was significantly lower than the control value, the degree of water stress would intensify. (3) The lower limits of soil moisture contents were suitable for the growth of Haloxylon ammodendron and Nitraria sibirica were 2.50% and 3.00%, respectively.

Abstract: In the majority of farming-pastoral areas, Inner Mongolia, grassland slope was reclaimed recent years due to the increase of population. The resulting deterioration of ecological environment problem is becoming more and more serious. In 2012, the effect of reclamation on erosion, vegetation and soil characteristics were researched in Saiwusu of Damao County, Inner Mongolia. Results show: 1. Severe wind erosion in spring, also severe water erosion in summer were on the slopping field. 2. After cultivation, annual herb such as Salsols collina, Corispermum declinatum, Chenopodum aristatum, Artimisia annua et al. grew vigorously, however perennial herb such as Stipa krylovii, Leymus chinensis and Agropyron cristatum were inhibited. 3. Soil nutrient sharp declined due to the erosion and harvest. In short, the grassland which converted to slopping field increases more than 5 times of soil erosion, soil fertility drops 30%, and vegetation changed completely after 1 year; 4 years later, soil fertility drops 50%, vegetation becomes sparse, soil water and fertility is poor, crop yield is low, the slopping field is not fit to continue farming, large abandoned.

Abstract: The Loess Plateau has the highest erosion rates in the world. Studying soil erosion process on the Loess Plateau has received more attention in recent years. Vertical erosion distribution zone is an important feature on the loess plateau. Infiltration, sediment concentration, erosion pattern and characteristic of sediment and water transportation have a clear distribution too. Research on soil erosion process can provide basis for constructing physical process based soil erosion mode and can provide scientific basis for laying out soil and water conservation measures effectively. So, spatial variability of slope erosion pattern, sheet, rill, shallow gully and permanent gully erosion process dominated at different erosion zone as well as slope-gully coupling system were discussed in this paper. And then, further research issues have been presented in the future.

Abstract: Biotic and abiotic factors how to influence soil respiration in different young monoculture plantations are not clearly understood. Soil respiration and its controlling factors were studied in six monoculture plantations in the coastal area of Shanghai, China. Soil respiration was significant difference among six stands. Variations of soil respiration in six plots were not directly related to changes in soil water content, but significant relationship was observed between soil respiration and soil temperature. The variation of soil respiration was firmly correlated to the variation of leaf area index (LAI) or gap fraction (GF), soil respiration enhanced with the increase of GF (or decreasing LAI). The microclimate within forest and soil temperature also had positively correlation with soil respiration, but which mainly were affected by GF or LAI. There was no significant relationship between soil respiration and either root biomass or soil nutrients.

Abstract: The labile fractions of organic carbon (OC) in soil can respond rapidly to changes in C supply and have been suggested as a sensitive indicator of soil quality. The object is to determine soil organic C and its labile fractions at the duration of different flooding. Three elevation gradient sites were chose: below 145m (permanently flooding site), 145-175m (seasonal flooding site), and above 175m (never flooding site) in the riparian zone of Three Gorges reservoir Area. The results showed that soil OC, dissolved organic C (DOC) and water-soluble carbohydrate (WSCh) were lower under seasonal flooding sites than those of never flooding upland and permanently flooding sites, whereas microbial biomass C (MBC) decreased with the flooding duration. Correlation analysis showed that soil OC and MBC had significantly positive relationship with DOC. The results suggested that seasonal flooding significantly affected soil OC and its labile fractions in the riparian zone of Three Gorges reservoir Area.

Abstract: Both soil temperature and soil water condition are important factors that influence soil respiration at different forest. In this study, a throughfall exclusion experiment was carried out to explore effects of increased soil temperature and decreased soil water content on soil respirations in the bamboo forest in North Zhejiang of China. The results showed that 1) monthly variation in soil respiration ranges from 2.00 to 0.63μmol·m^-2·s^-1 and 2.20 to 0.66μmolm^-2s^-1in throughfall exclusion and control plots respectively. The soil respiration monthly variation following the monthly variation of soil temperature and in contrast to the monthly soil water content. 2) Soil temperature can explain 65.5%and 73.9% of the variance of soil respiration in throughfall exclusion and control plots respectively. Multivariate linear model based on temperature and soil water content explained 66.9% and 73.4% of the variance of soil respiration in throughfall exclusion and control plots respectively. Soil water content had no significant relationship with soil respiration. Q₁₀ values of throughfall exclusion and control plots were 5.99 and 4.44.