Table of Content

25 August 2011, Volume 28 Issue 4 Previous Issue    Next Issue

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Desertification Process and Its Mechanism of Steppe Vegetation in the Hulunbeir Sandy Steppe, Inner Mongolia ZHAO Ha-lin, ZHOU Rui-lian, WANG Jin, ZHAO Xue-yong, ZHANG Tong-hui 2011, 28 (4):  565-571.  Abstract ( 1770 )   PDF (322KB) ( 1141 )   A field investigation on vegetation difference and change properties among different kinds of sand lands was conducted in the Qingbarhu Banner, Hulunbeir Sandy Land of Inner Mongolia in 2009 to understand desertification process and its mechanism of steppe vegetation. The results are as follows: (1) With development of desertification, the vegetation coverage, height, aboveground and underground biomass and litter yield of the steppe were sharply decreased, and the species richness, Shannon-Wiener index, Pielou evenness index and plant density were decreased in a fluctuation way; (2) Vegetation coverage, height and biomass were the most sensitive to desertification, and the response of species richness, biodiversity index and plant density to desertification was slow and lagged; (3) In desertification process, the effect of perennial high-quality forage was decreased but that of annual forbs was increased gradually in the community, the succession was gradually shifted from the community dominated by perennial gramineous plant Agropyron cristatum to the community dominated by annual gramineous and Chenopodiaceae plants, Setaria viridis+Corispermum macrocarpum; (4) In desertification process, soil coarseness, loose degree increase and decrease of soil organic matter and nutrient contents were the primary factors to cause vegetation degeneration, soil temperature and moisture content also affected the vegetation degeneration of the steppe to a certain extent, but the impact of soil bulk density and pH value on vegetation degeneration was quite low. References | Related Articles | Metrics

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Monitoring of Dynamic Change of Land Desertification in the Minqin Oasis during the Period of 2003-2008 WEI Huai-dong, ZHOU Lan-ping, XU Xian-ying, LI Ya, DING Feng, CHANG Zhao-feng, YANG Zi-hui 2011, 28 (4):  572-579.  Abstract ( 1800 )   PDF (514KB) ( 1663 )   On the basis of TM image interpretation, this study was to monitor the dynamic change of land desertification with an area of 8 355.20 km2 in Minin Oasis and its peripheral areas during the period from 2003 to 2008. The results show that land desertification was serious and its area accounted for more than 80% of the monitored area. The desertification land in Minqin Oasis was divided into two types, i.e. the wind-eroded desertification and salinized desertification, and it was distributed in the oasis and its peripheral areas in a zonal way. In 2003, the total area of land desertification in the monitoring area was 671 333.08 hm2. and accounted for 80.35% of the total area; in 2008, it was reduced to 670 396.13 hm2. and accounted for 80.24% of the total. During the period from 2003 to 2008, the area of land desertification was reduced by 936.95 hm2. and occupied 0.11% of the total in the monitoring area, in which the areas of wind-eroded desertification land and salinized desertification land were 0.49 hm2. and 936.45 hm2. respectively. Viewing from the desertification degree, the areas of serious desertification land and slight desertification land were reduced by 4 347.15 hm2. and 172.00 hm2. respectively, but the area of moderate desertification land was enlarged by 3 582.21 hm2. The reduced desertification land was mainly distributed in the oasis and its peripheral zonal regions of 0-2 km and 4-6 km in width, in which the area of reduced desertification land was the largest in the peripheral zonal region of 0-2 km, then in the oasis, and it was the smallest in the peripheral zonal region of 4-6 km; the enlarged desertification land was mainly distributed in the peripheral zonal region of 2-4 km and 6-20 km in width, and the enlarged extent was small. The desertification index of the Minqin Oasis was 2.256 5 in 2003 and 2.249 3 in 2008 respectively, it was between the moderate index and the serious one, and it was slightly decreased. Therefore, the development of land desertification was holistically kept within limits. References | Related Articles | Metrics

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Wind Regime and Its Geomorphologic Significance in the Hinterland of Gurbantonggut Desert GUO Hong-xu, WANG Xue-qin, JIANG Jin, ZHAO Xin-jun, HU Yong-feng 2011, 28 (4):  580-585.  Abstract ( 1988 )   PDF (536KB) ( 1392 )   Gurbantonggut Desert is the largest fixed and semi-fixed desert in China. In this study a statistical analysis on wind regime and sand drift potential at two weather stations located in the hinterland of the Gurbantonggut Desert was carry out during the period from 2003 to 2006. The results are as follows: The occurring frequency of sand transport wind is 0.25% in the central area of the desert and 0.11% in the south area. The prevailing wind directions are northeast wind and northwest wind in the central area but southwest wind and northwest wind in the south area. In the central area, the sand drift potential (DP) and resultant sand drift potential (RDP) are 66.7 VU and 25.7 VU respectively, and the resultant sand drift direction (RDD) is 197.0°. DP and RDP in the south area are 29.8 VU and 16.3 VU respectively, and RDD is 108.4°. Both the central and south areas of the Gurbantonggut Desert belong to the low wind energy environment according to Fryberger's classification. Sand transport wind in the study area occurs mainly in spring and summer, the percentage of DP from April to October accounts for 90% in the central area, and that from April to August in the south area accounts for 85%. Affected by strong wind and corresponding wind directions (northeast and northwest) in the central area, the ridge of longitudinal dune-chains extends along the resultant wind direction, and the dune chains are high. Affected by southwest and northwest winds in the south area, an eastward deflexion of the ridge of longitudinal dune-chains occurs, and a subsidiary ridge appears. References | Related Articles | Metrics

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Study on Distribution of Ephemeral Gullies in Semiarid Loess Area ZHAO Wei-jun, XU Zhi-chao, ZHANG Yan, ZHU Yan, ZHU Qing-ke 2011, 28 (4):  586-591.  Abstract ( 2184 )   PDF (469KB) ( 1354 )   Ephemeral gully (EG) erosion is one of the important ways of soil erosion in semiarid loess area. Extraction of ephemeral gullies from small watersheds was based on the SPOT image of Wuqi County in 2004, and the correlations between land use, slope and distribution of ephemeral gullies above shoulder line of valleys were analyzed based on the investigated date of land use in 35 small watersheds in Wuqi County, north Shaanxi Province. The results reveal that the EG density was in an order of hilly dry land < woodland < grassland; the EG density is significantly different from different land use types. Correlation analysis reveals that there was a positive correlation between the average slope and EG density in the same land use types, and ephemeral gullies are mainly distributed in a slope range from 25° to 35°. The study results can be referred in regenerating the ecology and conserving water and soil. References | Related Articles | Metrics

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Study on Spatiotemporal Change of Groundwater in the Ejin Basin XI Hai-yang, FENG Qi, SI Jian-hua, BAO Yin-hua, WANG Lin-bang 2011, 28 (4):  592-601.  Abstract ( 1496 )   PDF (661KB) ( 1179 )   In this paper, the spatiotemporal change of groundwater level in the Ejin Basin is analyzed based on the long-term monitoring data of groundwater level during the period from 1988 to 2006 and the groundwater level survey data in recent years using the geostatistical analysis method, the geostatistical characteristics and heterogeneity of groundwater depth are discussed, and the geostatistical model is used to fit the heterogeneity of groundwater depth. The results show that a continuous decline of groundwater level in the Ejin Basin had occurred since the 1940s, and it was more serious in the downstream area than that in the upstream area; the phreatic water level has started to rise again along with the increase of river discharge in recent years, but the deep confined water level is continually dropped, and the annual fluctuation range of phreatic water is higher than that of confined water. Spatially, groundwater depth increases at first and then decreases from the south to the north and decreases gradually from the west to the east. The groundwater level elevation decreases gradually from the south to the north, and it is U-shaped from the west to the east, that is the groundwater level elevation decreases at first and then increases. There is holistically a moderate spatial correlation of groundwater depth in spatial distribution, but there is a strong spatial correlation at four different directions in the Ejin Basin. The variable range of groundwater depth is 0.406° (longitude and latitude unit, about 33.7 km), that means there is a spatial autocorrelation in such variable range of groundwater depth. References | Related Articles | Metrics

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Game Analysis on Redistribution of Water Resources in the Tarim River Basin LI Xiao-yan, ZHANG Jie-bin 2011, 28 (4):  602-608.  Abstract ( 1840 )   PDF (392KB) ( 1339 )   Tarim River is one of the longest inland rivers in China and even in the world. The mainstream of the Tarim River was fed by its all nine headstreams in history. However, the headstreams were decreased to 4 in recent 50 years with the rapid population growth and artificial oasis enlargement, and the discharge of the mainstream of the Tarim River was also reduced sharply and continuously. The contradiction between supply and demand of water resources has become more serious, and a series of water environment problems occurred in the Tarim River Basin. These problems restricted seriously the social and economic development in the Tarim River Basin, and water crisis was exacerbated by water supply-demand contradiction. Fundamentally, the increasing water problems in the drainage basin are the game results of various stakeholders considering from their own interests. In this paper, a game model was developed and used to find out and analyze the contradiction in redistributing water resources under the imperfect initial water rights, the incentive and regulating mechanisms were developed for water consumption, and some safeguard measures were put forward from the administrative, legal, economic and technological aspects so as to ensure the successful implementation of the mechanisms. The purpose of developing the mechanisms is to shift the redistribution of water resources from the non-cooperative game to cooperative game, alleviate the conflicts between the individual interests sand collective interests, which are very important for sustainable development, utilization and management of water resources in the Tarim River Basin. References | Related Articles | Metrics

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Relationship between Spatiotemporal Variation of Water Pollution and Runoff Volume of Mainstream Section of the Weihe River in Shaanxi Province WANG Tai-ran, SUN Gen-nian, LIU Shun-yan 2011, 28 (4):  609-615.  Abstract ( 1991 )   PDF (468KB) ( 1329 )   In order to control environmental capacity divisionally in time-sharing way, in this paper the water quality monitoring data measured during the period from 2000 to 2004 were used to analyze the spatiotemporal variation of the 4 main pollution factors and their relationships with runoff volume of mainstream section of the Weihe River in Shaanxi Province. The result are as follows: (1) Permanganate index, ammonium ion and the BOD concentration were in an increase trend at all the cross sections, but the DO was in a decrease trend; (2) The annual variation of permanganate index at all the cross sections was relatively low, but the variation of BOD along the river section close to the urban area was intensive and in an increase trend year by year; (3) There was a significant negative exponent correlation between the permanganate index and ammonium; (4) There was an extreme value of runoff volume for the variation of permanganate index and ammonium ion concentration, when the runoff volume of the river was higher than the extreme value, an enough self-cleaning capability of the river could be maintained; on the contrary, stream water would be further polluted. The study results can be referred for achieving the goal of the coordinated development of economy and environment in the Weihe River Basin. References | Related Articles | Metrics

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Effects of Vegetation Types on Soil Quality in the Loess Hilly-gully Region DONG Li-li, ZHENG Fen-li 2011, 28 (4):  616-621.  Abstract ( 1606 )   PDF (310KB) ( 947 )   Soil quality is one of the most important environmental factors in sustaining the earth biosphere and developing sustainable agricultural product. Zhifanggou catchment of Ansai county of Shaanxi province was selected as the study area. Field investigations had been carried out and 8 sample plots with different vegetation types and ages were chosen. The effects of vegetation types on soil properties were analyzed through measuring soil particle size distributions, soil water stable aggregates, soil organic matter, total nitrogen, alkali-hydrolyzable nitrogen, ammonium nitrogen, nitrate nitrogen, available phosphorus, soil enzyme activities (invertase, alkaline phosphatase, and urease catalase), microbial biomass (carbon, nitrogen and phosphorus). The effects of vegetation types on soil quality were studied by calculating soil quality index (SQI) using factor analysis and membership function. Results indicate that SQI were 0.09-0.73, SQI in the crop land was the lowest, which was 0.09;SQI in the Robinia pseudoacacia forestland with 31-years age was the highest, which was 0.73. Under the same vegetation type, SQI increased with an increase of restoration year. Meanwhile, under the same restoration year, SQI in the Robinia pseudoacacia forestland was greater than that in the Pinus tabulaeformis forestland. These results showed that vegetation restoration and abandoned land can improve soil quality and extensive agricultural farming can decrease soil quality. References | Related Articles | Metrics

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Analysis on Soil PSD and Its Affecting Factors at Different Depths in Oasis Farmland —A Case Study in the Qira Oasis GUI Dong-wei, LEI Jia-qiang, ZENG Fan-jiang, MU Gui-jin, PAN Yan-fang, LI Kai-feng 2011, 28 (4):  622-629.  Abstract ( 1824 )   PDF (421KB) ( 1100 )   It is important to characterize the change of soil environment and its affecting factors in oasis for protecting oasis stability and achieving rational development in the process of oasification. In this study, the Qira Oasis was selected as the study area to analyze the change of soil particle size distribution (PSD, an important soil physical property) and its affecting factors at different depths based on the fact that farmland was the main land use type in the oasis. Fractal theory was used to describe PSD based on the PSD data at depths of 0-20 cm, 20-40 cm, 40-60 cm and 80-100 cm in sample plots in the oasis. According to the comparing and clustering analysis of PSD fractal dimension, the study result revealed that there was a significant difference of PSD among the sample plots at each depth, and the differences of farmland use years and locations were the main reasons resulting in the difference of soil PSD. At the depth of 60 cm, the dominant factor resulting in the difference of soil PSD was the farmland use years, especially at depth of 0-20 cm. However, its effect was gradually decreased with the increase of depth, and even there was no any important effect at depth of 80-100 cm. Therefore, there is a positive effect for PSD and soil environment to protect farmland which ensure the sustainable cultivation of farmland in the process of oasification. References | Related Articles | Metrics

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Analysis on Functional Diversity of Edaphon Communities in Medicago sativa Fields of Different Growth Years Based on Biolog-ECO Plates DONG Li-guo, JIANG Qi, CAI Jin-jun, ZHANG Yuan-run, XU Hao, LI Sheng-bao 2011, 28 (4):  630-637.  Abstract ( 2450 )   PDF (656KB) ( 1659 )   In this paper, the Biolog-ECO plates (Biolog, USA) were used to study the functional diversity of edaphon communities in Medicago sativa fields of different growth years in a semiarid loess hilly region. The results are as follows: (1) In the 0-15 cm soil layer, the average absorbance value in vigorous Medicago sativa fields was significantly higher than that in the severely degenerated Medicago sativa fields, degenerated Medicago sativa fields and slope farmland, especially the slope farmland; in the 15-30 cm soil layer, the average absorbance value of severely degenerated Medicago sativa fields was the highest, and it was the lowest in degenerated Medicago sativa fields; (2) In the 0-15 cm soil layer, the Shannon-Wiener index, Pielou index, Simpson index and richness index of Medicago sativa fields were holistically higher than those of slope farmland. In the 15-30 cm soil layer, the diversity index of edaphon of slope farmland was similar to that of severely degenerated Medicago sativa fields but higher than that of degenerated Medicago sativa fields and vigorous Medicago sativa fields, and that of degenerate Medicago sativa fields was the lowest; (3) Principal component analysis (PCA) of functional diversity of edaphon reveals that the functional diversity of edaphon in soil layers of 0-15 cm and 15-30 cm of slope farmland was similar to that of degenerated Medicago sativa fields. The use status of different carbon sources of Medicago sativa fields of different growth years was different; (4) Diversity of edaphon was holistically in an order of vigorous Medicago sativa fields > severely degenerated Medicago sativa fields > slope farmland > degenerated Medicago sativa fields. References | Related Articles | Metrics

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Study on Gentianaceae in the Karakorum Mountains in China HUANG Xue-jiao, XU Hai-yan, FENG Yuan-zhong, YAN Ping 2011, 28 (4):  638-642.  Abstract ( 1723 )   PDF (321KB) ( 1547 )   In this paper, the classification and distribution of Gentianaceae are researched based on the data of field investigation and specimens. The results show that 19 species and 1 variety in 6 genera of Gentianaceae are recorded in the Karakorum Mountains in China, among them there is 1 newly recorded species of Karakorum Mountains in China, it is Lomatogonium thomsonii, there are 3 newly recorded species of Xinjiang in China, and they are Gentiana ludlowii, Gentiana crenulato-truncata and Swertia wolfangiana. There are 7 species in 1 polytypic genus of Gentianaceae and 12 species in 5 monotypic genera in the Karakorum Mountains in China; the relations of flora in this area are the closest with those in the Pamirs of China, the similarity coefficients of genera and species are 85.7% and 53.3% respectively; secondly, the relations of flora in this area are close with those in Afghanistan and the Qinghai-Tibetan Plateau, the similarity coefficients of genera and species are 42.9% and 6.1%, 37.5% and 7.2%, respectively. The distribution-type of genera in Gentianaceae is temperate nature in this area. The 89.5% species of Gentianaceae in this area are therophytes which contain 17 species in 5 genera, and therefore they are the dominating components in the plant life form spectrum in this area, and 10.5% species of Gentianaceae in this area are Hemicryptophytes which contain 2 species in 1 genus. References | Related Articles | Metrics

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Research on Spermatophyte Flora in the Xilingol Desert Steppe YUE Xiu-xian, LIU Guo-hou, LIU Hui-juan, HU Shun 2011, 28 (4):  643-648.  Abstract ( 1590 )   PDF (380KB) ( 1546 )   The local flora structure and the distribution characteristics of seed plants in the Xilingol desert steppe were studied based on wild vegetable survey by processing the data, analyzing the plant families, genera and species and applying the methods of botany and phytogeography. It is suggested to protect and utilize rationally the wild plant resources in the study area, and an important reference is provided as the scientific basis to protect the local plant species. The results show that the local plants belong to the desert steppe flora. So far 348 endemic species in 180 genera and 55 families in the Xilingol desert steppe were recorded. In which there were 4 species in 2 genera and 2 families of Gymnosperm and 344 species (including 31 varieties) in 178 genera and 53 families of Angiosperm. Composed by the families and genera, the plurimotypic families (including more than 10 species), monotypic genera and oligotypic genera were the main part of the local flora and the main sources of flora complexity and species diversity to be as the widely distributed local species. At family level, the proportion of Gramineae, Compositae, Leguminosae, Chenopodiaceae, Cruciferae and Polygonaceae was the highest, there was a trend that the floristic element laid in big families of spermatophyte, and the dominance of plurimotypic families was evident. The proportion of 45 families with less than 10 species was 81.83% of the total families in the region. At genus level, although plurimotypic genera and plurotypic genera were the dominant species of local plant communities and the typical components, but they were not the main part, they had an important influence on the structure of flora and vegetable composition. The single-species genera and few-species genera are the main part of the local flora and the main sources of the local flora complexity and species diversity to be as the widely distributed local species. After analyzing the floristic geographical element of genera and species, the results reveal that the temperate element genera and species were the main part of the local flora, the geographic element of the flora was the multiplicity, and the temperate element was the main part of local flora; the temperate element characteristics were the typical features of local flora. The main floristic feature was temperate, but it was affected by pantropical element to a certain extent. The comparison of similarity coefficients of various florae (including the Dalai Lake Nature Reserve, the Dalinor National Nature Reserve, Otindag Sandy Land and Alxa Desert) reveals that the flora had an affinitive relationship with Alxa desert, and the seed plant flora in the steppe had the obvious desertification characteristics. The analysis of floristic geographical element and distribution characteristics in Xilingol desert steppe also indicated that the climate and environmental conditions, ecological amplitude and adaptive capacity of plants affected determinatively the floristic geographic distribution. References | Related Articles | Metrics

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Comparative Study on Effects of NaCl and Polyethylene Glycol on PSII Activity of Hippophae rhamnoides LI Li, LV Xiang-fang, PAN Xiang-liang, LI Hong, CHEN Bao-jun 2011, 28 (4):  649-654.  Abstract ( 1882 )   PDF (452KB) ( 939 )   Effects of polyethylene Glycol (PEG-6000) and NaCl on PSII activity of Hippophae rhamnoides were investigated by an experiment carried out in greenhouse. Both NaCl and PEG exposure restricted the electron transfer in acceptor, resulted in a decrease of energy yield into electron transfer chain. The two stresses still caused the decrease of chlorophyll content, but had no effect to the density of active photosynthetic reaction centers (RC/CSo). Compared with PEG treatment, NaCl exposure was higher in absorption flux, trapped energy flux and electron transport flux per excited reaction center (ABS/RC, TRo/RC, ETo/RC), but it had lower value in performance index (PIABS) due to the decrease in electron transport (φEo), probability that a trapped exciton moves an electron into the electron transport chain beyond Q-A (Ψo). Our results suggested that NaCl inhibited more intensely the PSII activity than PEG, as had close relation with specific ion effect of NaCl. References | Related Articles | Metrics

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Preliminary Study on Dormancy and Germination of Cynomorium songaricum Seed DONG Song-lin, CHEN Nian-lai, ZHANG Yong, LI Cai-xia, GAO Hai-ning 2011, 28 (4):  655-659.  Abstract ( 1744 )   PDF (411KB) ( 1298 )   In order to understand the parasitic property of Cynomorium songaricum, the dormancy and germination properties of C. songaricum seeds are researched. The seed germination was promoted with both physical and chemical ways. The results show that the C. songaricum seeds are small, and the embryo of matured seeds develops incompletely and at the globular proembryo stage all the time before and after germination. The results testified that the germination of C. songaricum seeds need a certain stimulating signal form the host roots; exogenous GA3 and ethylene solution have a function of breaking the dormancy of C. songaricum seeds. References | Related Articles | Metrics

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Study on Air Decontamination Function of Picea schrenkiana in the Tianshan Mountains ZHOU Yue-ming, CHANG Shun-li, ZHANG Yu-tao, SHI Qing-dong 2011, 28 (4):  660-664.  Abstract ( 2442 )   PDF (402KB) ( 1080 )   In this paper, the functions of adsorption and filtration of Picea schrenkiana forest to the main air pollutants are analyzed by monitoring and measuring the dynamic trends of dustfall amount and TSP in Picea schrenkiana forest and the sulphur content in Picea schrenkiana leaves at different altitudes, on which the air decontamination function of Picea schrenkiana forest is evaluated. The results are as follows: (1) The dustfall amount in the forest with canopy density of 0.8 was the highest in June and July, it was increased by 4.88 g/(m2·30 d) (34.8%) compared with that in an open contrast zone, and the air decontamination value of the forest was 2.17 yuan/(m2·30 d); (2) Rainfall and human activities affect significantly TSP concentration, the caught TSP in air over the forest can be increased by 0.052 mg/m3 compared with that in the open contrast zone, and it can be increased by 70.3% in maximum; (3) Correlation between the sulphur content in Picea schrenkiana leaves and altitude is not significant. In the threshold for injury, the sulphur content in leaves is increased with the increase of SO2 concentration in air, it is the highest (1.44 mg/g) at altitude of 2 300 m a. s. l., and the average SO2 decontamination value of each Picea schrenkiana tree is 2.16 yuan. References | Related Articles | Metrics

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Population Ecology of Tetraonchus monenteron in Esox lucius Linnaeus in the Ertix River ZHAO Jiang-shan, JIAO Li, WANG Bo-liang, Guli Jamal Mamat, YUE Cheng 2011, 28 (4):  665-668.  Abstract ( 1789 )   PDF (359KB) ( 905 )   The population ecology of Tetraonchus monenteron was investigated by analyzing the field-collected samples. The results show that the prevalence and infection intensity were different from different host groups with different body lengths, the mean prevalence was 45.4%, the mean infection intensity was 11.8±6.05, the prevalence was decreased but the infection intensity was increased with the increase of host body length; the mean abundance and the variance-mean ratio of Tetraonchus monenteron in the host Esox lucius Linnaeus were increased at first and then decreased with the increase of host body length, and the variance-mean ratio was higher than 1 in all the host groups with different body lengths, the over-dispersion of parasite population in host population was observed, and the degree of the aggregation increases with the increase of mean abundance. References | Related Articles | Metrics

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Spatiotemporal Distribution of Climate Change over the Qinghai-Tibetan Plateau in 21st Century CHENG Zhi-gang, LIU Xiao-dong, FAN Guang-zhou, BAI Ai-juan, WANG Bing-yun 2011, 28 (4):  669-676.  Abstract ( 2206 )   PDF (680KB) ( 1222 )   By comparing the data calculated with 23 models from the IPCC Fourth Assessment Report, precipitation data from GPCP and air temperature data from ECMWF, the spatiotemporal distribution of air temperature and precipitation over the Qinghai-Tibetan Plateau in 21st century was analyzed by using the output data of 11 models and the high-resolution dynamical downscaling data on A1B scenarios. The result of 11-model ensemble mean shows that the air temperature and precipitation will increase by 1.98 ℃ and 0.06 mm/d in the mid-21st century compared with those in 2008, but by 3.93 ℃ and 0.24 mm/d at the end-21st century. The results analyzed with the dynamical downscaling reveal that there will be the significant wetting and warming trends over the Qinghai-Tibetan Plateau in next 100 years, the spatial distribution of precipitation will be quite uneven, and there is a big uncertainty in simulating precipitation variation. References | Related Articles | Metrics

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Study on Wind Speed in Winter and Its Relation with Surface Sensible Heat in Spring and Summer over Northwest China CHEN Juan, LI Dong-liang, WANG Hui, CHEN Lian 2011, 28 (4):  677-687.  Abstract ( 1943 )   PDF (1197KB) ( 1419 )   In this paper, the spatial distribution and time evolution of wind speed over northwest China in winter in recent 37 years from 1970 to 2006 were analyzed base on EOF analysis, sharp climate change test and correlation analysis. The spatial distribution pattern and temporal variation trend of surface sensible heat in spring and summer as well as the correlation between wind speed in winter and surface sensible heat in next spring and summer in the arid regions of northwest China during the period of 1982-2006 were investigated and examined. Results show that the average wind speed over northwest China in winter in recent 25 years was significantly decreased, and wind speed was universally high in the 1970s, decreased in the 1980s, universally low in the 1990s, and increased slowly during the period from 2000 to 2006. The interdecadal variation and sharp change of wind speed accorded basically with the change of surface sensible heat in next spring and summer. There was a good positive correlation between wind speed in winter and surface sensible heat in next spring and summer, and the significant correlation occurred in the Tianshan Mountains, Qiemo, Hashun Gobi Desert, Kumtag Desert and west Inner Mongolia. References | Related Articles | Metrics

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Climatic Characteristics of Sunshine Duration in the Tianshan Mountains of Xinjiang ZHAO Yong, CUI Cai-xia, LI Yang 2011, 28 (4):  688-693.  Abstract ( 3181 )   PDF (613KB) ( 1320 )   Based on the daily sunshine duration data observed at 23 weather stations in the Tianshan Mountains during the period of 1961-2008, the spatiotemporal distribution and variation features of sunshine duration in the Tianshan Mountains were analyzed using some statistical methods, such as the simple linear regression and Mann-Kendall test. The results are as follows: (1) There was an obvious regional difference in climatic distribution of sunshine duration, and the sunshine duration increased from the west to the east and from the north to the south in the Tianshan Mountains; (2) The regional average sunshine duration was in a decrease trend, especially in winter and summer; (3) There was an obvious decadal variation trend of seasonal sunshine duration except that in spring, and a sharp decrease of seasonal sunshine duration occurred in winter 1987, summer 1978 and autumn 1980; (4) The sharp decrease of sunshine duration in winter and summer was related to the serious air pollution and the increase of cloud cover in recent 20 years. References | Related Articles | Metrics

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Characteristics of Sandstorm Weather in China in March 2010 XUE Zhan-jin, QIN Zuo-dong, MENG Xian-wen, FAN Xiao-hui 2011, 28 (4):  694-698.  Abstract ( 1396 )   PDF (505KB) ( 1296 )   Sandstorm is a kind of serious disastrous weather and results in some disadvantageous impacts on industrial and agricultural production, traffic, people's daily life and air quality. In March 2010, 6 times of sandstorm weather occurred in China, including 1 time of severe sandstorm, 3 times of sandstorm and 2 times of blowing sand weather, which were more than those in the same period in recent ten years (4.2 times), and the sandstorm weather was characterized by the concentrated occurring period of time, late time of the first occurrence, vast affecting area, etc. The analyzed results show that, under the geographical background of climate change and sand sources, the main reasons of sandstorm occurrence were the temperature increase, infrequent rainfall, strong cold air current and strong Mongolian cyclone in March 2010. References | Related Articles | Metrics

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Satellite Observation on Rainfall Enhancement in Stratiform Clouds over Shaanxi Province in Spring 2009 LIU Gui-hua, YU Xing, JIA Ling, YUE Zhi-guo, DAI Jin 2011, 28 (4):  699-704.  Abstract ( 1356 )   PDF (1403KB) ( 1051 )   Because of the advantages of cloud detection with satellite, the cloud structure and precipitation formation process can be analyzed from different configurations of cloud thickness, particle size and cloud top properties by the retrieval and multi-spectral analysis of satellite data, and consequently the potential of rainfall enhancement can be investigated based on the assumptions of rainfall enhancement and the available research achievements. A new applicable tool will be provided for satellite detection of the conditions of precipitation enhancement. A precipitation process of stratiform clouds from 7 to 8 February, 2009 was selected to analyze rainfall enhancement with MODIS polar orbiting satellite data. The retrieval microphysical characteristics of the clouds are as follows: (1) The cloud top temperature was about -10 ℃, the effective radius (Re) of cloud top was around 10 μm, the cloud body was thick, and the clouds were rich in supercooled water but lack of ice crystals or large drops at daytime of 7 February; (2) Rainfall occurred under the participation of high clouds; (3) There was a good opportunity for rainfall enhancement because of the existence of sustained and stable low-level stratiform clouds. Cloud tracking with FY2C geostationary satellite revealed that the cloud system lasted for 30 hours, in which clouds grew thick gradually with stable Re and less rainfall from the daytime to the night of 7 February. Although precipitation process of such clouds was weak, there was a good potential for precipitation enhancement operation. After the comprehensive analysis, the suitable criteria for detecting rainfall enhancement of supercooled stratiform clouds with satellite can be summarized as: the thickness of clouds is about 2 km, and cloud top temperature ranges from -10 ℃ to -20 ℃ with Re less than 15 μm. References | Related Articles | Metrics

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Cloud Detection in Xinjiang Based on MODIS Data ZHANG Xu, CUI Cai-xia, MAO Wei-yi, YANG Zhi-hua, CHEN Ai-jing 2011, 28 (4):  705-709.  Abstract ( 1691 )   PDF (755KB) ( 1082 )   Precipitation is closely related to clouds. Artificial weather stations and weather forecast radar detection are the primary means of cloud observation, but the means are sometimes unable to obtain the comprehensive and accurate cloud cover data due to the natural constraints and human error. Reference to a variety of domestic and foreign cloud detection methods, in this study the multispectral cloud detection algorithm based on the combination of index method and spectral threshold method was used to detect cloud cover conditions over Xinjiang using MODIS1, 6, 26-channel data. The analyzed results show that the average annual cloud cover duration in Xinjiang in 2009 was 82 days, in which the average annual cloud cover duration was 101 days in the mountainous regions and 69 days in the plains, respectively. References | Related Articles | Metrics

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Analysis on Input of Atmospheric Nitrogen Dry Deposition in Urumqi ZHANG Wei, LIU Xue-jun, HU Yu-kun, LI Kai-hui, SHEN Jian-lin, LUO Xiao-sheng, SONG Wei 2011, 28 (4):  710-716.  Abstract ( 1746 )   PDF (497KB) ( 1053 )   Atmospheric concentrations of NH3, NO2, particulate NH4+ (PNH4+) and NO3- (PNO3-) were measured from the samples collected with passive samplers and particulate samplers in Urumqi and its suburbs during the period from August 2009 to March 2010 to estimate atmospheric dry deposition of nitrogen (N) in this region. The results show that NH3 concentration at the Institute of Soil and Fertilizer Research (ISFR, suburban site) was higher than that at the Xinjiang Institute of Ecology and Geography (XIEG, urban site), while the concentrations of other atmospheric reactive N compositions (NO2, particulate NH4+ and NO3-) were higher at XIEG than those at ISFR. The mean concentrations of NH3-N, NO2-N, PNH4+-N, PNO3--N and PM10 (particulate matters with aerodynamic diameter less than 10 μm) at XIEG were 4.49, 4.31, 2.52, 11.84 and 225 μg/m3, and those at ISFR were 4.63, 2.32, 2.34, 7.59 and 188 μg/m3, respectively. Based on the measured concentrations and the dry deposition velocities cited from the references, it was estimated that the atmospheric dry deposition of N was 28.7 kg/(hm2·a) during the sampling period at XIEG and 21.6 kg/(hm2·a) at ISFR, in which the proportion of NHx (NH3+ PNH4+) accounted for 65.7% at XIEG and 69.4% at ISFR, NH3 was dominant during the period from August to November, and PNH4+ was dominant during the period from December to next March. References | Related Articles | Metrics

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Analysis on Atmospheric Boundary Layer Structure and Its Effect on Air Pollution over Urumqi City in Winter YANG Jing, WU Jiang-yan, LI Xia, PENG Cheng-hai, WANG Zhong-wei 2011, 28 (4):  717-723.  Abstract ( 1735 )   PDF (463KB) ( 1524 )   Effect of meteorological conditions of atmospheric boundary layer on air pollutant dispersion is significant, but there have been few studies on atmospheric boundary layer characteristics over Urumqi yet. During December 11-20, 2005, the sounding experiment in urban atmospheric boundary layer over Urumqi City was performed six times a day. Atmospheric boundary layer conditions, such as wind, temperature, mixing layer depth and temperature inversion, were analyzed. The results show that wind speed near ground surface was often lower than 3 m/s, and it was increased gradually with the increase of height below 600 m. The temperature inversion of ground-based and low level-elevated was higher than 1 ℃/100 m, and the daily mean mixing layer depth was 274 m. The meteorological conditions in two durations of air pollution at severe and light levels were compared. Wind speed was lower and temperature was higher during severe air pollution than that during light air pollution. In addition, the temperature inversion intensity during light air pollution was very high (4.5 ℃/100 m), but its inversion depth was low (166 m). The results reveal that the severe air pollution in Urumqi was mainly caused by the simultaneous decrease of wind speed in atmospheric boundary layer, labilization of the prevailing wind direction near ground surface, continuous surface temperature increase, and formation of unstable stratification below exhaustsmoke height of chimneys. The formation and stable continuance of the thick temperature inversion resulted in a long duration of severe air pollution. References | Related Articles | Metrics

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Effects of Different Carbon and Nitrogen Fertilizer Combination Treatments on Canopy CO2 Concentration, Photosynthesis and Yield Formation of Cotton Field under Drip Irrigation in Xinjiang YIN Fei-hu, GAO Zhi-jian, XIE Zong-ming, CHEN Guan-wen, LI Xiao-lan 2011, 28 (4):  724-728.  Abstract ( 3351 )   PDF (337KB) ( 1248 )   Based on pipe network system of drip irrigation under plastic film, the possibility of increasing cotton field canopy CO2 concentration and its effect were investigated via fertilization of dissolvable carbon fertilizer (water insoluble matter <1%). By setting different carbon and nitrogen fertilizer combination treatments, canopy CO2 concentration, leaf photosynthetic rate and yield formation of cotton field in Xinjiang were analyzed. The results show that canopy CO2 concentration was increased with the amount of carbon fertilizer increasing in cotton florescence. Under the conditions of providing adequate irrigation water and inadequate N fertilization, the leaf photosynthetic rate was higher under C300+N113.55 treatment (C300 means that the amount of ammonium bicarbonate was 300 kg/hm2), and N113.55 means that the amount of nitrogen was 113.55 kg/hm2, and it was the lowest under C600+N0 treatment. The seed cotton yield under C300+N113.55 treatment was the highest, and it was the lowest under C600+N0 treatment. There was a significant difference in seed cotton yield among different carbon and nitrogen fertilizer combination treatments. References | Related Articles | Metrics

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Spatiotemporal Evolution of Cotton Production in the Tarim River Basin in Recent 30 Years ZHANG Xin-huan, WANG Chang-yan, TANG Hong, XIAO Yan-qiu 2011, 28 (4):  729-736.  Abstract ( 2565 )   PDF (636KB) ( 1392 )   The Tarim River Basin is one of the most appropriate areas to produce cotton in China. It has become as the main area to produce high-quality cotton in China because of its natural advantages since recent decades. Based on the statistical data of cotton production during the period of 1949-2007, in this paper the spatiotemporal evolution of cotton production in the Tarim River Basin was analyzed based on the development index and suitability index. The results are as follows: (1) Cotton production in the Tarim River Basin was developed remarkably during the period from 1949 to 2007. The process of cotton production development was divided into three phases, i.e. the slow progress during the period of 1949-1985, rapid growth during the period from 1986 to 1999, and controlled expansion from 2000; (2) With the rapid development of cotton production, the major cotton production areas were reduced in the west Tarim River Basin while expanded eastward and northward. The development trend of cotton production could be divided into 5 evolution types, i.e. the steady predominance, promotional predominance, declining predominance, feeble predominance and naught predominance; (3) Suitability of cotton production in the Tarim River Basin is different from different regions. The counties with suitable temperature, abundant arable land and enough water resources around the mainstream of the Tarim River were the suitable regions to plant cotton. Several counties in the north Tarim River Basin are unsuitable for cotton production because of unfavorable climate. Other counties are the hypo-suitable regions to plant cotton; (4) The preponderant cotton production areas around the mainstream of the Tarim River correspond with the suitable region of producing cotton. Some cotton production areas are irrationally expanded. The cotton production areas with steady predominance are distributed in the suitable regions of producing cotton. Some cotton production areas with promotional predominance are in the suitable regions, and some in the hypo-suitable or unsuitable regions. The other cotton production areas were mainly in the hypo-suitable and unsuitable regions. References | Related Articles | Metrics