Table of Content

15 July 2012, Volume 29 Issue 4 Previous Issue    Next Issue

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Analysis on Recent Change of Water Area of the Main Lakes in Xinjiang Based on MODIS Data BAI Rui-Dong, HE Long-Hua, WU Jing-Lu 2012, 29 (4):  561-566.  Abstract ( 1796 )   PDF (2433KB) ( 1007 )   The change of water area of the lakes in Xinjiang is an important indicator of climate change and disturbance of human activities. Based on the MODIS images, this paper analyzed the change of water area of 11 lakes with a water area larger than 100 km2 in Xinjiang during the period from 2000 to 2011. Results showed that the interannual variation of the 11 lakes was observably distinct, their smallest total area (4 585 km2) occurred in 2001 and their largest one (5 277 km2) in 2003. Although the variation of water area of the lakes in Xinjiang was significant and frequent in recent years, the water area of many lakes was in an increase trend. Analysis from the aspects of altitudes and geographical locations revealed that the lakes over the Qinghai-Tibetan Plateau, such as the Ayakkum Lake, were expanded in recent years; the area of those in the mountainous regions, such as the Sayram Lake, was basically stable; the lakes in the debouchure oases, such as the Bosten Lake, were in a shrinkage; and the lakes in plains, such as the Ebinur Lake and Manas Lake, were extremely unstable. The apparent diversity of water area from different altitudes and regions was jointly affected by both natural factors and human activities. However, the change of water area was mainly affected by climate change in recent years. References | Related Articles | Metrics

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Computation and Analysis of Water Vapor Content in the Tianshan Mountains and Peripheral Regions, China YAO Jun-Qiang, YANG Qing, HUANG Jun-Li, ZHAO Ling 2012, 29 (4):  567-573.  Abstract ( 1717 )   PDF (2296KB) ( 1073 )   The values of monthly mean water vapor content were computed using meteorological data from 3 radiosonde stations including Yining, Kuqa and Urumqi in the Tianshan Mountains and peripheral regions in Xinjiang, China during the period of 1976-2009, and a formula involving monthly mean water vapor content and surface vapor pressure was developed. The values of water vapor content at 44 meteorological stations in the Tianshan Mountains and peripheral regions during the period of 1961-2009 were computed and analyzed, the temporal and spatial distribution pattern of water vapor content and its relationship with precipitation was researched. Results are as follows: (1) There were three regions with high water vapor content in the Tianshan Mountains and peripheral regions, located in the valley plains in north piedmont of the Tianshan Mountains and Turpan Basin, and the water vapor content varied in a range of 12-21 mm. South Tianshan Mountains and Aksu, Korla and Hami were the regions with second high water vapor content, and the water vapor content varied in a range of 5-13 mm. The central and east parts of the Tianshan Mountains were the regions with low water vapor content, and the water vapor content varied in a range of 4-8 mm; (2) The variation curve of monthly water vapor content was unimodal, water vapor content was the highest in summer but lowest in winter, and the seasonal variation was significant. Water vapor content was increased during the period from February to July, its increase rate was the highest in March but the lowest in July, and the increase rates in these two months were 65.8% and 17.6% respectively. Water vapor content was decreased during the period from August to next January, its decrease rate was the highest in December but the lowest in August, and the decrease rates in these two months were 38.5% and 7.8% respectively. Monthly mean water vapor content in the Tianshan Mountains (7.83 mm) was lower than the average in whole Xinjiang (10.51 mm), in which the monthly mean and summer water vapor contents were the highest in the west Tianshan Mountains, they were 9.88 mm and 18.94 mm respectively; (3) The decadal variation of water vapor content was low during the period of 1961-2009, but water vapor content fluctuated significantly and was in an obvious increase trend after 1986; (4) There was no good correlation between water vapor content and precipitation. References | Related Articles | Metrics

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Response of Groundwater Level to the Ecological Water Conveyance in the Lower Reaches of the Tarim River LU Yan-Ling, YE Chao-Xia 2012, 29 (4):  574-578.  Abstract ( 1254 )   PDF (1909KB) ( 921 )   In this study, the dynamic change of groundwater level before, after and during the 12th ecological water conveyance to the lower reaches of the Tarim River in Xinjiang, China was researched, the temporal and spatial change of groundwater level was analyzed, and the relationship between groundwater level change and distance of monitoring wells away from the river channel was lucubrated. The results show that the raise extent of groundwater level was increased upstream and with the decrease of distance away from the ricer channel, and it was affected by that whether the place was flooded by conveyed water and by conveyed water volume. The analyzed result of the relationship between conveyed water volume and raise extent of groundwater level is of significance for understanding the recent effect of ecological water conveyance on groundwater level raise in the lower reaches of the Tarim River. It is considered that the long-term and stable ecological water conveyance is very important for the growth of natural vegetation and the ecological regeneration in the lower reaches of the Tarim River. References | Related Articles | Metrics

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Enzyme Activities and Physical and Chemical Properties of Five Different Soils in the Ebinur Lake Basin LIU Xiao-Xing, 吕Guang-Hui , YANG Xiao-Dong- , ZHANG Hai-Feng 2012, 29 (4):  579-585.  Abstract ( 1548 )   PDF (1592KB) ( 1159 )   In this paper, a case study was carried out in the Ebinur Lake Basin to reveal the correlations between enzyme activities and physical and chemical properties of different soils in a desert in arid area. The results indicated that the physical and chemical properties were different from different soils, the soil properties of chernozem and chestnut soil were better than that of other soils types, and there was a regularity in vertical distribution of physical and chemical properties. Enzyme activities were different from different soils, there was no distinct descending of enzyme activities along the soil profiles except along chernozem profile. There was also a significant positive correlation among soil enzyme activities, which indicated that there were the mutual promotion and interactional relationship among soil enzyme activities. There was a very significant positive correlation between soil enzyme activities and soil organic matter content and total N content in soil, and a significant positive correlation or very significant positive correlation between soil enzyme activities and soil moisture content. There was a very significant negative correlation between some soil enzyme activities and soil pH value. In contrast, there were no significant correlations between soil enzyme activities and total salt content and available phosphorus content. The correlations between soil enzyme activities and soil physicalchemical properties were different from different soils, which indicated that the main soil physical and chemical factors affecting soil enzyme activities were different from different soils. References | Related Articles | Metrics

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Research on the Spatial Variability of Soil Alkaline Phosphatase and Urease Activity in Highyield Cotton Field ZHU Xin-Ping, JIA Hong-Tao, ZHENG Chun-Xia, JIANG Ping-An, WANG Li 2012, 29 (4):  586-591.  Abstract ( 1793 )   PDF (1409KB) ( 886 )   The spatial variability of soil alkaline phosphatase and urease activity at different cotton growth stages was researched by sampling and testing the activity of alkaline phosphatase and urease in soil samples collected from the 10 m×10 m sample plots in a highyield cotton field. Their semivariogram figures and contour figures were charted using the method of geostatistics, and their horizontal and vertical spatial variability and temporal variability with cotton growth were lucubrated. The results showed that the variability of activity of alkaline phosphatase and urease in soil was moderate at three cotton growth stages. In vertical direction of soil, urease activity(0-20 cm) was higher than CV of urease activity(20-40 cm), the same as alkaline phosphatase activity. The vertical spatial variability of soil alkaline phosphatase and urease activity was different, the variability coefficient of urease activity in soil layer of 0-20 cm was higher than that in soil layer of 20-40 cm, but the vertical spatial variability of soil alkaline phosphatase was opposite. There was also the temporal variability of soil enzyme in cotton field, and the activity of soil alkaline phosphatase and urease was decreased with the increase of soil depth at three cotton growth stages. References | Related Articles | Metrics

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Effect of Longterm Fertilization on Soil Organic Carbon and Soil Inorganic Carbon in Oasis Cropland RONG Jing-Rong, LI Chen-Hua, WANG Yu-Gang, TANG Li-Song, CHEN Xiao-Min 2012, 29 (4):  592-597.  Abstract ( 1752 )   PDF (1895KB) ( 1231 )   In this study, the Fukang Station for Desert Ecological Research, Chinese Academy Sciences, was regarded as a platform to lucubrate the dynamic change of soil carbon content, soil carbon sequestration potential and longterm oasis agricultural nutrient cycling, including the distribution of soil inorganic carbon content (SIC) and organic carbon content (SOC) along soil profile and at different fertilization time under the different soil fertilization treatments, such as the treatment without fertilization (CK), single fertilizer application (NPK), and fertilization treatment with straw (S) in arid area. The results showed that the fertilizer application, soil depth and fertilization time affected significantly the SOC content and SIC content in soil (P<0.01).Compared with CK, the SOC content and SIC content under NPK, M and S were significantly increased (P<0.05),and the SIC content under the organic/inorganic fertilizing combination (M) was significantly higher than that under chemical fertilizer application. The average SIC content was increased from 9.12 g/kg in soil layer of 0-20 cm in depth to 9.17 g/kg in soil layer of 20-40 cm and to 9.94 g/kg in soil layer of 40-60 cm respectively, but the SOC content was contrary. These revealed that the rational fertilization could increase the organic carbon content in topsoil, and the carbon sequestration in soil could be increased under organic/inorganic fertilizing combination (M). References | Related Articles | Metrics

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Soil Moisture Properties in Four Types of Wetland in Gahai WANG Yuan-Feng, WANG Hui, MA Wei-Wei, FENG Yi-Ming, LI Jun-Zhen 2012, 29 (4):  598-603.  Abstract ( 1726 )   PDF (680KB) ( 1030 )    In this paper, the soil moisture content, soil bulk density, soil porosity, retention capacity of soil water and soil water storage of peatland, marsh wetland, mountains wetland and flood wetland in Gahai were researched. The results are as follows: (1) The soil moisture contents in peatland, marsh wetland, mountains wetland and flood wetland were 225.13%, 159.46%, 179.47% and 111.78% respectively; (2) The soil bulk density of four types of wetland increased with the increase of soil depth. In soil layer of 0-80 cm, the soil bulk densities of peatland, marsh wetland, mountains wetland and flood wetland were 0.89 g/cm3, 1.17 g/cm3, 1.11 g/cm3and 1.18 g/cm3 respectively; (3) In four types of wetland, the soil capillary porosity, non-capillary porosity, retention capacity of saturated soil water, retention capacity of soil water and soil water storage were decreased gradually with the increase of soil depth; (4) In peatland, marsh wetland, mountains wetland and flood wetland, retention capacities of soil capillary water were 2.50, 1.51, 1.00 and 1.78 times of soil weight, and retention capacity of saturated soil water were 2.83, 1.81, 1.25 and 2.08 times of soil weight, respectively; (5) In four types wetland, soil in peatland was looser, its porosity was larger, its ventilation was better, and retention and storage of soil water storage was higher than those of others. References | Related Articles | Metrics

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Assessment on Soil Fertility of Planted Forests in the Northeast Sandy Area of the Ulanbuh Desert YANG Xiao-Juan, LIAO Chao-Ying, SUN Wen-Yan, BAO Yao-Xian, LI Lu-Ping 2012, 29 (4):  604-608.  Abstract ( 1405 )   PDF (703KB) ( 969 )   In this study, the effect of vegetation on soil fertility was researched so as to guide the local vegetation construction. Nine pieces of planted forest in the northeast sandy area of the Ulanbuh Desert were taken as the study area,and 16 indicators of soil physical, chemical and biological properties were selected through the sensitivity analysis and principal component analysis to derive the integrated fertility index (IIF)calculated with the fuzzy comprehensive evaluation approach. The content of physical clay < 0.01 mm, degree of aggregation, organic matter content, total N content, bacterial population and urease activity were selected as the soil fertility indicators, which could reflect the most information of soil fertility, and the coefficient of determination was 0.940 5. Holistically, the value of soil fertility was in an order of shrubbery > woodland > sandy land, shrubbery could improve soil, and IIFof Caragana korshinskii was the highest. Therefore, the native nitrogenfixing shrubs should be considered as the dominant planted species, and some tree and herb species should also be selected, however, it is not suitable to plant trees in large area. References | Related Articles | Metrics

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Water Absorbent Capacity of Super Absorbent Polymer with Different Granularities and Its Effect on Soil Physical Properties LI Xing, JIANG Jin, SONG Chun-Wu, CHEN Ming- , ZHANG Yun-Chao, ZHANG Heng 2012, 29 (4):  609-614.  Abstract ( 1705 )   PDF (1697KB) ( 1583 )   In this paper, the effects of super absorbent polymer (SAP) on soil physical and chemical properties and the relationships among water absorbent capacity of SAP with three different granularities (2.0-3.2 mm, 1.0-2.0 mm and 0.5-1.0 mm) were studied in laboratory. The results showed that there was a negative correlation between water absorbent rate and SAP granularity. Soil moisture content could be significantly increased and soil evaporationcould be restricted after applying SAP. Soil pH value and electrical conductivity could be increased after　applying SAP, the proportion of liquid phase in soil could be increased, but that of gas phase decreased, and soil permeability could also be decreased. In general, the improving effects of SAP with medium granularity on soil physical and chemical properties, such as soil water content, pH value, total porosity, permeability and electrical conductivity, were the highest, especially when the proportion of applied SAP was 0.1%. References | Related Articles | Metrics

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Analysis on Community Structure of Picea crassifolia Forests in the Qilian Mountains ZHAO Wei-Jun, LIU Xian-De, JIN Ming, CHE Zong-Xi, JING Wen-Mao, MA Yu 2012, 29 (4):  615-620.  Abstract ( 2293 )   PDF (1335KB) ( 1126 )   In this paper, the features of Picea crassifolia pure forests at regional scale were analyzed by selecting three typical P. crassifolia forests in the Haxi, Xishui and Qifeng forest centers in the eastern, middle and western parts of the Qilian Mountains in China. The community structure characteristics, including the layer structure, DBH, height structure and static distribution of crown diameter structure of P. crassifolia forests in the designed temporary plots, were investigated. The regression correlations among these three indexes(DBH, height and crown diameter) were developed. The results are as follows: (1) Four layers, i.e. the arborous, shrub, herb and moss layers, could be observed. To some extent, the structure characters of arborous layer were negatively correlated with that of shrub and herb layers. Furthermore, moss in the middle part of the Qilian Mountains developed well; (2) The DBH of P. crassifolia in eastern part of the Qilian Mountains was in an “intermittent” type, and it was in a “reverse J” type in the middle part and a “unimodal” type in the western part. Moreover, the analyzed result of structure of the tree height and crown diameter showed that the regeneration of P. crassifolia was unhealthy in the study area; (3) In the different regions and sample plots, DBH, height and crown diameter of P. crassifolia were significantly correlated with each other, the regression model Y=aXb(P<0.01) could be used to depict their correlations. It is believed that these results can provide the theoretical basis for sustainable management, community regeneration and tending management of P. crassifolia forest in the Qilian Mountains. References | Related Articles | Metrics

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Response of Main Osmotic Adjustment Substances to NaCl Stress Accumulation in Atriplex canescens WANG Xin-Ying, SHI Jun-Hui, LIU Mao-Xiu, CHEN Qi-Min 2012, 29 (4):  621-627.  Abstract ( 1321 )   PDF (1905KB) ( 797 )   In this study, Atriplex canescens(Pursh) Nutt. plants were cultivated in sand-pots and irrigated with NaCl water so as to research the response of main osmotic adjustment substances to NaCl  concentration and stress time for 1, 5, 10, 20, 40 and 60 days respectively. The result are as follows: (1) The effects of stress time on proline, K+, Na+ and Cl- contents and K+/Na+ ratio in A. canescens leaves were extremely significant. The proline and Na+ contents in A. canescens leaves were increased with the stress time, but the K+ content and K+/Na+ ratio was decreased. The change of Cl- content was complicated. Proline and Na+ contents were slightly increased when the stress time was shorter than 40 days but increased significantly when the stress time was longer than 40 days; (2) The effects of NaCl concentration on the proline, K+, Na+ and Cl- contents and K+/Na+ ratio in A. canescens leaves were extremely significant. The proline and Na+ contents were increased with increasing NaCl concentration, but K+ content and K+/Na+ ratio was decreased. Under high NaCl concentration, the Na+ and proline contents were significantly increased, but the K+ content and K+/Na+ ratio was significantly decreased; (3) The ion transportation of A. canescens was selectable. Under salt stress, K+ was selected to transport from roots to stems, but Na+ was still remained in roots; Na+ was selected to transport from stems to leaves, the transportation of K+ to leaves was restricted, and K+ was transported from roots to stems; the K+/Na+ ratio in different vegetative organs was in an order of stem > leaf > root, and the ratio was decreased with increasing NaCl concentration. In conclusion, the effects of NaCl concentration on proline, K+ and Na+ contents and K+/Na+ ratio were increased with the NaCl stress time, and the interaction between NaCl concentration and stress time affected significantly the proline, Na+ anad Cl- contents in A. canescens leaves. Therefore, the time scale and interaction between NaCl concentration and stress time should be considered in further research in the future. References | Related Articles | Metrics

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Study on Dynamic Status of Litter Decomposition and Nutrients of Typical Desert Plants ZHAO Hong-Mei, HUANG Gang, MA Jian , LI Yan, FAN Lian-Lian, ZHOU Li 2012, 29 (4):  628-634.  Abstract ( 1668 )   PDF (2265KB) ( 882 )   As one of the most important ecosystem processes, litter decomposition is closely related to plant nutrients, ecosystem productivity and carbon and nutrient cycling, particularly to soil organic carbon pool-size and its stabilization. During last decades, numerous studies on litter decomposition in moist environment was conducted. However, there was few information about litter decomposition in arid area. Litter decomposition in arid area is different from that in moist environment owing to severe natural climate, such as sporadic rainfall, intense solar radiation, long-term drought and serious water loss and soil erosion. In recent studies, it was found that there is a discrepancy between simulated decomposition rates and measured ones in arid area. It is considered that ephemeral plants are important for net primary productivity in some deserts, and particularly for soil carbon input. The aims of this study are to investigate the dynamic status of litter decomposition of three typical desert species. Litter bag method was used to investigate the decomposition rate and nutrient release of roots, stems and leaves of Eremurus inderiensis, Erodium oxyrrhynchum and Seriphidium santolinum. Mass loss curves of leaves, stems and roots of these species were well described by an exponential decay model. Mass loss rates of leaves and roots of E. inderiensis, leaves, stems and roots of E. oxyrrhynchum, stems and roots of S. santolinum were 41.96%, 81.94%, 42.18%, 29.32%, 47.02%, 20.66% and 20.71% respectively. During the 364day decomposition in field, the decomposition rates were different from different species litters, and they were in an order of roots > leaves of E. inderiensis, roots > leaves > stems of E. oxyrrhynchum and roots > stems of S. santolinum. N and P release was observed throughout the decomposition process, N and P contents in litters were negatively correlated with mass loss. In addition, decomposition rate was significantly different at different decomposition stages. In conclusion, the decomposition rates of litters of desert ephemeral plants were high, and the decomposition time and litter types are the important factors of decomposition in arid area. References | Related Articles | Metrics

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Effects of Different Irrigation Volumes on Water Consumption and Growth of Elaeagnus oxycarpa SHI Ce, FAN Wen-Bo, ZHU Hong-Kai, WANG Jiu-Long 2012, 29 (4):  635-640.  Abstract ( 1412 )   PDF (895KB) ( 924 )   Elaeagnus oxycarpa  is a pioneer species planted for water and soil conservation in arid area. In this study, neutron probe and oven drying method were used to monitor the change of soil moisture content, water consumption and water consumption intensity of E. oxycarpa were calculated using the water balance principle, and the growth of E. oxycarpa was analyzed. The results show that water consumption of E. oxycarpa was increased with increasing the irrigation volume, and the total water consumptions under 6 irrigation volumes were 172.14 mm, 301.11 mm, 346.92 mm, 372.53 mm, 428.74 mm, 564.62 mm and 631.96 mm respectively. The change of water consumption modulus was similar to the variation of the corresponding water consumption. Water consumption of E. oxycarpa in May and June was higher than that in other months, and the average daily water consumption intensity was also in a gradual increase trend with increasing the irrigation volume. All the growth indexes of E. oxycarpa were increased with increasing the irrigation volume in an irrigation volume range of 30-90 mm, but their differences were not significant when the irrigation volume was higher than 90 mm, especially the response of new branch length to irrigation volume was the most sensitive. Proportion of wilting coefficient of E. oxycarpa accounted for 11.33% of the field water capacity. Growth of E. oxycarpa could not be restricted when the field water capacity maintained higher than 49.15%. References | Related Articles | Metrics

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Spatiotemporal Distribution of Soil Moisture Content and Aboveground Biomass under Different Terrains in Desert Steppe FANG Kai, SONG Nai-Ping, WEI Le, AN Hui 2012, 29 (4):  641-647.  Abstract ( 1538 )   PDF (1206KB) ( 1022 )   It is of significance to investigate soil moisture content and aboveground biomass under different terrains in desert steppe for understanding the effects of terrain on spatiotemporal heterogeneity of soil moisture content and aboveground biomass. Based on the TDR and field survey, we analyzed the heterogeneity of soil moisture content and aboveground biomass under 3 different terrains using the multivariate analyses, such as the oneway ANOVA, multiple comparison and Kriging interpolation. We also used the person correlation coefficient to analyze the relationship between soil moisture content and aboveground biomass and to clarify the effects of soil moisture content in different soil layers on vegetation at different growth stages.  The  results  are as follows: (1) The vertical distribution of soil moisture content was obvious, and CV was the lowest in soil layer of 0-20 cm but the highest in soil layer of  60-80 cm. The spatial heterogeneity of aboveground biomass was significant in whole growth season; (2) Soil moisture content and its spatiotemporal distribution pattern were different among the 3 different terrains, it means that terrain was the key factor affecting soil moisture content; (3) Terrain was not the main factor affecting the spatial variation of grassland productivity, and it affected significantly the dynamic vegetation growth but slightly the aboveground biomass; (4) The relationship between soil moisture content and aboveground biomass was different at different growth stages. Water consumption for vegetation growth at the initial growth stage was mainly from soil layer of 60-100 cm; there was a weak correlation between soil moisture content and biomass at other growth stages, which may be related to the formation time of drought-tolerant organs of plants. References | Related Articles | Metrics

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Change in Surface Mean Wind Speed of Northeast China during the Period of 1971-2010 JIN Wei, REN Guo-Yu, QU Yan, LIU Xiao-Ling 2012, 29 (4):  648-653.  Abstract ( 1856 )   PDF (2037KB) ( 1687 )   In this paper, the data of monthly surface wind speed in northeast China during the period from 1971 to 2010 were used to study the temporal and spatial change of average surface wind speed in three provinces (Liaoning, Jilin and Heilongjiang) in northeast China. The results are as follows: (1) For the entire period (40 years), the mean surface wind speed in these three provinces during the 40year period was significantly decreased with a rate of -0.23 m·s-1·(10 a）-1. During the 30year periods of 1971-2000 and 1981-2010 as well as the 20year period of 1991-2010, mean surface wind speed was in a significant decrease trend with rates of -0.25m·s-1·(10 a）-1,-0.20m·s-1·(10 a）-1 and -0.17m·s-1·(10 a）-1, and the values were all statistically significant at 0.001 confidence level; (2) For the entire study period, the average seasonal surface wind speed was significantly decreased, and the decrease was the most significant in spring, then in winter, fall and summer. All seasonal trends for the whole period were significant at 0.001 confidence level. The average monthly surface wind speed was also consistently decreased; (3) Average annual wind speed in northeast China in recent 40 years was significantly decreased except that at one or two stations. During recent 20 years, the average surface wind speed was in a decrease trend in most areas, but the sites with significant decrease trend were in a reduction, and those with increase trend were in an increase, especially in the central and western parts of northeast China in recent 10 years. References | Related Articles | Metrics

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Climate Characteristics and Forecast of Relative Humidity in Wuwei City LIU Ming-Chun, YANG Xiao-Ling, YIN Yu-Chun, HU Jin-Ge 2012, 29 (4):  654-659.  Abstract ( 2443 )   PDF (1694KB) ( 1307 )   In this paper, the spatiotemporal distribution and change trend of relative humidity were systematically analyzed based on the mean relative humidity data observed by 5 meteorological stations in Wuwei City during the period from 1960 to 2009. The result shows that relative humidity was low in the north but high in the south. Annual and decadal relative humidity was holistically in a decrease trend, and there was a 6-8 year periodic change. Relative humidity was the highest in summer, than in autumn, it was the lowest in spring, holistically in an increase trend  in winter, and in a decrease trend in other seasons. Relative humidity was the highest in August and September and the lowest in April, and it was high in the morning and evening but low around noon. There was a counter correlation between the diurnalvariations of relative humidity and temperature. The daily ECMWF numerical forecast grid field data at 20:00 during the period from 2003 to 2007 were used, the forecast factor was initially elected with Press criterion, the forecast factor was chosen with stepwise regression forecast method, and the relative humidity forecast equations were developed with optimal subset regression. The overall situation and the most superior significance forecast equations of mean monthly relative humidity were determined with the CSC double grading criterion, and the prognostic equations were at a confidence level of  α=0.01. Back substitution fitting rate of the prognostic equations varied in a range of 70%-77%, and the forecast accuracy rate in a range of 65%-72%. Objective and effective instruction products could be provided for forecasting relative humidity. References | Related Articles | Metrics

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Observed Change of Extreme Climatic Events in Shijiazhuang BIAN Tao, REN Guo-Yu, YUE Yan-Xia, ZHAO Wei-Liang 2012, 29 (4):  660-666.  Abstract ( 1461 )   PDF (3606KB) ( 879 )   In this paper, the changes of frequency and intensity of extreme temperature and precipitation events were analyzed using 8 extreme temperature indices and 5 extreme precipitation indices based on the daily temperature and precipitation data observed by 17 meteorological stations in Shijiazhuang during the period of 1972-2009. Results showed that warm days tended to increase, but cold days, frost days and ice days tended to decrease, especially there was a significant decrease of cold days and frost days. The increase of warm indices and the decrease of cold indices were the most significant at the stations in the eastern part of the study area. There was a slight increase of extreme maximum and minimum temperature, and also a significant increase trend of annual lowest values of maximum temperature and the highest values of minimum temperature. The spatial distribution of 4 extreme temperature indices was quite different, and there was a slight increase of heavy rain days and rainstorm days. There was also a slight increase of maximum 1-day and 3-day precipitation, but such trend was not significant at most stations. The linear trend of rainstorm intensity was only 0.83 mm/（d·10 a）, and the increase or decrease trend of heavy rain intensity accorded with that of rainstorm at most stations. References | Related Articles | Metrics

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Analysis on the Correlation between ]NDVI and Tree-ring Width Chronologies in the Upper Reaches of the Shiyang River LU Jun-Wei, WANG Nai-Ang, HOU Ying, ZHANG Xue-Min, CHANG Jin-Long 2012, 29 (4):  667-673.  Abstract ( 1855 )   PDF (2049KB) ( 766 )   In this study 160 tree cores were collected from Picea crassifolia in the upper reaches of the Shiyang River. After mounted, polished, cross dated and measured, the tree-ring width chronologies in the study area were developed. The monthly normalized difference vegetation index（NDVI）for the period from January 1982 to December 2006 was created using the GIMMS/NDVI data with the 8 km×8 km resolution from the NASA Goddard Space Flight Center. It was found that the annual NDVI curves were unimodal, the main growth season lasted from May to August, and the annual change of NDVI during the period of 1982-2006 was decreased in a fluctuation way. The relationships among tree-ring width index, NDVI and climatic data were analyzed. The results showed that both tree-ring width index and NDVI were strongly affected by precipitation during the period during non-growth period from September to next April, there was a significant positive correlation between tree-ring width index and precipitation during this period, but a significant negative correlation between NDVI and precipitation. The correlation between NDVI and tree-ring width index in plant growth season was poor, but there was a good negative correlation between them in non-growth season (r=-0.667, p<0.01). References | Related Articles | Metrics

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Study on Change of Extreme Temperatures in Gansu Province during the Period of 1960-2009 WANG Bao-Long, ZHANG Ming-Jun, WEI Jun-Lin, HUANG Xiao-Yan, WANG Sheng-Jie 2012, 29 (4):  674-680.  Abstract ( 1313 )   PDF (3035KB) ( 915 )   In this paper, the methods of regression analysis, inverse distance weighted and Mann-Kendall test were used to analyze the temporal and spatial variation of extreme temperature events in Gansu Province based on the daily and annual temperature data observed by 26 meteorological stations in the province during the period from 1960 to 2009. The thresholds of the extreme high temperature days and the extreme low temperature days at these stations were determined. Results indicated that the decadal trend of extreme temperature at these stations was basically similar, the annual extreme high temperature was in a slight increase, but the extreme low temperature was in a slight decrease. In spite of the above mentioned main trends in most regions, the spatial distribution differences were obvious. In addition, an obvious sharp change of extreme temperature indexes occurred in Gansu Province in recent 50 years. References | Related Articles | Metrics

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Study on Spatial Distribution of Drought Indices in the Weihe River Basin MA Ming-Wei, SONG Song-Bai 2012, 29 (4):  681-691.  Abstract ( 1566 )   PDF (7641KB) ( 946 )   In this paper, the drought actuality in the Weihe River Basin was investigated using drought indices based on the monthly precipitation data. A case study was carried out to compare the consistency and difference of the calculated results of Z-index and SPI at Xi’an Meteorological Station. The actuality and duration of historical drought and flood at the station at 1-month, 3-month, 6-month, 9-month, 12-month and 24-month time scales were analyzed, and the seasonal drought and flood features at the station were lucubrated. The SPI values at different time scales in the Weihe River Basin in November 1995 were computed to obtain their spatial distribution. It was found that Z-index was not suitable for describing the features of drought at shorttime scale. The SPI values at multi-time scales can be used to reflect the distribution of precipitation, which is an effective method for monitoring and predicting drought. The results also indicated that severe drought occurred in 1995 in the Weihe River Basin possessed the evident seasonal and multi-year features, and the drought severity decreased holistically from the southeast to the northwest. References | Related Articles | Metrics

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Wind and Water Erosive Forces in a Desertloess Ecotone—A Case Study in Jingbian County, Shaanxi Province YANG Yan-Yan, LIU Lian-You, CAO Heng-Wu 2012, 29 (4):  692-698.  Abstract ( 1565 )   PDF (1902KB) ( 884 )   In this study, a case study was carried out to research rainfall erosion, wind regime and resultant sand-transporting potential in Jingbian County located in a desert-loess ecotone in Shaanxi Province during the period from 2007 to 2009. The results are as follows: ① The rainfall events with precipitation ≥12 mm occurred during the period from May to September, the monthly rainfall erosion was the highest in August 〔318.24 MJ·mm/(hm2·h·a)〕, and the average annual rainfall erosion was 510.08 MJ·mm/(hm2·h·a); ② The direction of prevailing wind in the study area was northwest, then southeast, and their cumulative frequencies were 43.8% and 16.21%. The sandraise wind (6-9.9 m/s) occurred mainly during the period from March to June, and the occurring frequencies in these months were 19.34%, 12.34%, 20.5% and 12.39% respectively; ③ The average sand drift potential (DP) and resultant sand drift potential (RDP) were 228.76 VU and 41.73 VU respectively, the RDP/DP of wind direction was 0.2, and the resultant sand drift direction was 114.17°. All these show that the study area is in a moderate wind energy environment, the variability of monthly wind direction was high, and sand was transported southeastward. References | Related Articles | Metrics

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Study on Structure of Windblown Sand Flow over the Desert Ecotonein the Northern Marginal Zone of the Taklimakan Desert YANG Xing-Hua, HE Qing, A Ji-Gu-Li-Sha-Yi-Ti- , CHENG Yu-Jing 2012, 29 (4):  699-704.  Abstract ( 2086 )   PDF (1978KB) ( 1059 )   The damage of wind-lown sand flow is multiaspect, not only its destruction to soil surface texture and reduction of soil anti-rodibility, but also the affection on air quality and human activities. The Taklimakan Desert is the largest, warmest and driest desert in China, and it is also known as one of the  largest mobile deserts in the world and one of the main source fields of sandstorm in China. So it is of signality to study the structure of wind-lown sand flow. In this paper, the structure of wind-lown sand flow over the Xiaotang area in a desert ecotone in the Taklimakan Desert was studied. The results showed that the proportion of transported sand quantity within a 30-m height was higher than 47.3% of the total transported sand quantity near ground surface, and this result was different from that in previous studies. The transported sand quantity with height above ground surface changed in a power function way. The particle size distribution analysis of windblown sand sediment collected from different soil layers showed that the proportion of fine sand, very fine sand and silt was dominant (>99%). The average particle size was decreased with the increase of height. In windblown sand flow, wind profile near ground surface was not in a logarithmic distribution but in a power function distribution (u=azb).   References | Related Articles | Metrics

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Study on Severe Dust Storms and Their Disasters in Inner Mongolia Based on Copulas Function LIU Xue-Qin, LI Ning, JI Zhong-Hui, ZHANG Peng, GU Xiao-Tian 2012, 29 (4):  705-712.  Abstract ( 1964 )   PDF (1746KB) ( 847 )   This paper discussed the importance and the deficiency of multivariate analysis in researching natural disasters and describing the theory and methods of Copula function, which is widely used in financial field. On which a case study on severe sandstorm events in Inner Mongolia during the period of 1990-2008 was carried out. The joint distribution of 10-minute average maximum wind speed and duration of severe sandstorm disasters were revealed, and the return periods under different encounters were calculated. After comparing the return periods based on single variable, the obtained joint return periods were exacter. The case study showed that the Copula function can be used to simulate severe sandstorm disasters well. The results can be referred in working out the disaster reduction strategies and putting forward the measures of controlling severe sandstorm disasters, and also in further researching the risk of natural disasters. References | Related Articles | Metrics

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The Features of Ionic Components of TSP and Their Affecting Factors over Urumqi LIU Xin-Chun, ZHONG Yu-Ting, HE Qing, YANG Hao 2012, 29 (4):  713-720.  Abstract ( 1945 )   PDF (3077KB) ( 940 )   This paper analyzed the watersoluble ionic components of TSP over Urumqi in 2009 based on the data of atmospheric total suspended particles (TSP) measured with ion chromatographers at 4 observation sites. The results are as follows: (1) The total ion concentration which was averaged with the values measured at three stations over Urumqi City was 151.28 μg/m3, and the total ion concentration at Baiyang Station was 40.83 μg/m3. The ratio of NO3-/SO4 2-at all the 4 stations was low, which revealed that the atmospheric pollution was mainly from the fixed pollution sources in Urumqi; (2) SO42-, Ca2+, NO3- and NH4+ levels were higher than the other ions of TSP in 2009. There were the significant seasonal variations of concentration of ions. All the concentrations of ions, especially that of SO42-  and NO3-, were obviously increased in heating season; (3) Correlation analyses of all the ions were carried out, the results showed that the correlation coefficient between NH4+ and SO42-  was 0.828, and that between NH4 +and NO3 -was 0.659, these revealed that ammonium compounds were dominated by ammonium sulfate and ammonium nitrate. The correlation coefficient between NO3- and SO42-  was 0.973, which revealed that NO3- and SO42- came mainly from sulfur dioxide and nitrogen oxides. There was a good correlation between crust elements Ca2+ and Mg2+, and their correlation coefficient was as high as 0.914, which revealed that the sources of these two crust elements were similar, and these elements came mainly from dust weather, road dust and construction dust. References | Related Articles | Metrics

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Modern Sedimentation and Its Environmental Significance of the Bosten Lake OU Wen-Jia , LEI Huai-Yan, ZHANG Cheng-Jun 2012, 29 (4):  721-726.  Abstract ( 1642 )   PDF (1567KB) ( 1112 )   In this paper, the geochemical indicators of 27-cm shallow core samples collected from the Huangshui area in the Bosten Lake Basin were analyzed, their values were compared with the meteorological data observed by Yanqi Meteorological Station, and the environmental significance of modern sedimentation was discussed. The results show that climate change at that time (from 90 years ago to around 1980) was recorded well by the core samples at depth of 26-11 cm, that is, a dry climate change and an evaporation increase occurred at first, and then it became warmer with precipitation increase. The dominant factors of isotopic composition of organic matter and carbonate were changed due to the disturbance of human activities, input of external material sources and the eutrophication caused by industrial and agricultural sewage drainage in recent 40 years, thus the function of sediments in recording climate change was disrupted. References | Related Articles | Metrics

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Preliminary Study on Black Carbon Aerosol Pollution over Urumqi in Winter LI Shuai, GUO Zhi-Zhong, HU Lie-Qun, HE Qing, XU Zhi-De 2012, 29 (4):  727-734.  Abstract ( 1599 )   PDF (2279KB) ( 947 )   The features of BC aerosol over Urumqi in winter were analyzed based on the related black carbon aerosol, concentration of air pollutants and　meteorological data collected at Urumqi Atmospheric Environment Monitoring Station. The results showed that the average daily BC concentration was 6.55 μg/m3, the daily variation was significant, and there were the good correlations between the average daily BC concentration and API,PM10, PM2.5and NOx. The hourly variation of BC was significantly bimodal, which was related to the direct emissions from motor vehicles, human activities and heating with coal. The frequency of BC concentration occurred mainly in a range of 2-9 μg/m3, and its proportion was as high as 60% of all the observed values. Compared with other results, the BC level over Urumqi was higher than that in some foreign cities but relatively lower than that in most domestic cities. High BC pollution was mainly caused by air mass from the north and northwest. BC concentration began to decrease when wind speed was higher than 1.0 m/s, and the decrease could be close to 50%. There was no significant correlation between wind speed and BC concentration when wind speed was higher than 2.0 m/s. BC concentration in weekdays was higher than that in weekends. References | Related Articles | Metrics

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Analysis and Prediction of Land Use Change in Maqu County MA Yuan, HUANG Chong, ZHENG Wei 2012, 29 (4):  735-741.  Abstract ( 1490 )   PDF (2034KB) ( 994 )   Based on the detailed survey data of land use change during the period from 1975 to 2005, this paper analyzed quantitatively the static structure, dynamic change and main driving forces of land use change in Maqu County in southeast Qinghai-Tibetan Plateau. The results show that the area of forests and waters in Maqu County was reduced with the economic development and accelerated urbanization during the period of 1975-2005, the area of grasslands and land for urban expansion, rural construction and for expansion and construction of industrial, mineral and residential areas was enlarged, the information entropy of land use structure was holistically decreased, and the dominance value was gradually expanded. The integrated index of land use degree was increased by 0.076 5 during the period of 1975-1995, but it was decreased by 0.709 2 during the period of 1995-2005, these reveal that the land use degree was in development during the period of 1975-1995 but in a declining trend during the period of 1995-2005. According to the land use change characteristics of entropy, the GM (1, 1) model of grey theory was used to predict that the land use degree in Maqu County is in regulation during the period from 2006 to 2015. References | Related Articles | Metrics