Table of Content

15 September 2011, Volume 28 Issue 5 Previous Issue    Next Issue

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Rational Groundwater Exploitation and Utilization, an Important Approach of Improving Salinized Farmland in Xinjiang FAN Zi-Li, QIAO Mu, XU Hai-Liang, ZHANG Qing-Qing, LI He-Ping, ZHANG Peng, ZHOU Sheng-Bin, LU Lei 2011, 28 (5):  737-743.  Abstract ( 2743 )   PDF (1917KB) ( 1943 )   Soil salinization is serious in arid regions of Xinjiang. According to the interpretation of remote sensing images of CBERS in 2005 and the data of field investigation, the area of farmland in Xinjiang was 5.05×106 hm2, in which the area of salinized farmland was 1.62×106 hm2 and occupied 32.07% of the total farmland area and 60% of the medial and lowyield farmland. Soil salinization is a main factor restricting agricultural development in Xinjiang. Salinized farmland is mainly distributed in the regions with high groundwater level, such as the groundwater overflow zone in the marginal zone of alluvial fans, deltas of large rivers, upper and central parts of alluvial plains and lakeside plains of freshwater lakes, where groundwater recharge is abundant, groundwater salinity is not high, waterbearing condition of aquiver is good, pressure water or artesian water is distributed in some regions, and these regions are optimal to utilize groundwater. To exploit groundwater in these areas can not only increase irrigation water volume, solve the shortage of irrigation water in spring and at the irrigation peak time, but can also bring about a drawdown of groundwater level and achieve a steady desalination of salinized farmland. References | Related Articles | Metrics

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Hydrological Regime and Water Resources in the West Qilian Mountains CHEN Guang-Ting, ZENG Fan-Jiang 2011, 28 (5):  744-749.  Abstract ( 2326 )   PDF (1596KB) ( 1579 )   The stream system in the west Qilian Mountains includes the Shule River Basin and the Sugan Lake Basin, and the latter is merged into the former sometimes. The Shule River Basin is close to the Eurasian “drought center”, the annual precipitation in the plains there is more than 50 mm only, and it increases with the altitude in the mountains and can be up to more than 170 mm in maximum. Modern glaciers develop in the west Qilian Mountains under high altitude although the altitude of snow line is high, and the proportion of glaciersnow melt water is high in runoff volume. Along with climate change towards warmingwetting pattern, the annual precipitation is in an increase trend, glaciersnow melt is sped up, and the annual runoff volume at the debouchure is increased. The supplydemand contradiction of water resources become more and more serious and some serious ecological problems occur due to the excessive development of the piedmont oases. Only by relying on the rational redistribution of water resources and the construction of watersaving irrigation can the supplydemand contradiction of water resources be alleviated. References | Related Articles | Metrics

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Study on Dynamic Change of Groundwater Depth in a Newly Reclaimed Oasis in Northwestern Marginal Zone of the Junggar Basin LU Lei, ZHAO Zhen-Yong, MENG Min, QIAO Mu, ZHOU Sheng-Bin 2011, 28 (5):  750-755.  Abstract ( 2009 )   PDF (2292KB) ( 1298 )   Based on the measured data of groundwater level from the observation wells, this paper analyzes the temporal and spatial characteristics and affecting factors of groundwater level change in Karamay agricultural development region in the Junggar Basin. The results show that groundwater level in the study area was continuously raised during the period of 1997-2009. There was a direct relationship between the raise of groundwater level and the irrigation period in the study area. Groundwater depth was gradually raised from the northwestern marginal zone to the northeastern marginal zone of the basin. As a result, many centers with high groundwater level were formed. As the increase of both the number and extent of the centers of groundwater level raise, these areas may be connected. The effect of precipitation and temperature change on the dynamic change of groundwater depth was not significant, and it is considered that the increase of irrigation volume and recycled water were the main factors resulting in groundwater level raise. In order to control groundwater level, prevent soil salinization and promote sustainable development in the agriculture development region, it is essential to develop watersaving irrigation technique and work out a rational irrigation quota. References | Related Articles | Metrics

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Analysis on the Change of Flood and Its Formation Causes in the Piliqing River Basin WANG Jiao-Yan, XIE Lei 2011, 28 (5):  756-760.  Abstract ( 1720 )   PDF (1616KB) ( 997 )   The Piliqing River is located in the transport routeway of water vapour from the west in the west Tianshan Mountains, where the mountain body is high, the river valley is deep, mountain slope is steep, and flood occurs frequently. According to the hydrological data measured at Piliqing Hydrological Station in recent more than 50 years, the model comparison coefficient, variation coefficient and skew coefficient were all in an increase trend with the time, which reveals that the flood frequency and discharge were in an increase trend. After analyzing the data of air temperature, precipitation and silt content at Piliqing Hydrological Station, it was found that flood occurrence in the drainage basin during the period from April to July was closely related to the violent melt of thick snow cover and heavy rainfall. The frequent occurrence of flood was mainly caused by heavy snowfall in winter, continuous increase of temperature in spring and vegetation destruction caused by excessive pasturing in the mountainous region in the upper reaches. References | Related Articles | Metrics

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Evolution of Water Resources and Water Environment in Shijiazhuang City in Recent 50 Years HU Jun-Chun, GUO Chun-Qing, ZENG Cheng 2011, 28 (5):  761-767.  Abstract ( 3738 )   PDF (3154KB) ( 1144 )   In this paper, the deduction and induction are used to study the evolution characteristics of precipitation, surface water resources, groundwater resources, surface water environment, groundwater environment and their positive and negative feedbacks in Shijiazhuang City in recent 50 years based on the theory of hydrological cycle. On the basis of the systematic study on evolution of water resources and water environment, the internal connections and interactions among water cycle, water resources and water environment are lucubrated based on considering human activities, global warming and construction of the middle route of South-to-North Water Diversion Project, and the strategic planning of water resources in Shijiazhuang City in the future is explored. References | Related Articles | Metrics

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Mechanism and Ecological Role of Snowmelt Funnel of Populus euphratica YANG Xiao-Dong, LV Guang-Hui , CHANG Shun-Li 2011, 28 (5):  768-774.  Abstract ( 3335 )   PDF (1774KB) ( 1194 )   There is a snowmelt funnel around a  Populus euphratica trunk in Tugai forest. This paper analyzes the relationship between P. euphratica  crown and the shape of snowmelt funnel, and the difference of soil temperature, organic matter content and salt content in soil between the funnel area and the ground of forest gap. The results show that the salt content and organic matter content in soil under P. euphratica crown was higher than that of the ground of forest gap, which resulted in a higher soil temperature under the crown and the best capacity of insulation for forest when the frozen soil was melted in spring, because the soil under the crown could get more solar radiation and there was also a “fertile island effect”, thus a snowmelt funnel formed around a P. euphratica trunk. Water from snowmelt under the crown flowed to the roots of  P. euphratica in spring, which was advantageous for the growth of  P. euphratica forest. To some extent, snowmelt funnel can be used to explain the phenomenon of mutualism and associate among species. Taking the Tugai forest as an example, snowmelt funnels of  P. euphratica contribute to the survival of ephemeral plants in arid and semiarid areas. References | Related Articles | Metrics

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Comparison of Soil Water Properties and Soil Water Storage Capacity in Different Forest Habitats LIU Qing-Bai, LIU Ming-Guo, WANG Yu-Tao, TANG Jing-Chao 2011, 28 (5):  775-779.  Abstract ( 1928 )   PDF (516KB) ( 1157 )   In this study, the physical properties of soil moisture and soil water retention were measured in plots of 20 m×30 m in the mingled forest of Pinus tabulaeformis Carr. and Robinia pseudoacacia L., pure forests of P. tabulaeformis Carr. and R. pseudoacacia L., and nonforest land in Beipiao County of Liaoning Province. The results showed that the soil physical properties including soil porosity, soil mechanical composition, soil water retention, soil permeability and soil water storage capacity in the mingled forest of P. tabulaeformis Carr. and R. pseudoacacia L. were all better than those in the pure forests and nonforest land. All the values of soil in the pure forests of  P. tabulaeformis Carr. and R. pseudoacacia  L. were similar. The comprehensive evaluation revealed that soil water retention in the mingled forest of  P. tabulaeformis Carr. and R. pseudoacacia L. was the highest among the three forest types. The linear regression equations of the main factors affecting the saturated hydraulic conductivity (EMAS) were developed. References | Related Articles | Metrics

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Response of Seedling Emergence of Two Haloxylon Species to the Interchanging of Soil Matrix in Habitants and Sand Burial Depth LI Hui, LI Yan, FAN Lian-Lian 2011, 28 (5):  780-788.  Abstract ( 1871 )   PDF (3275KB) ( 1043 )   Field interchanging transplants and sand burial controlled experiments were conducted on Haloxylon ammodendron and H. persicum to compare the seed germination, seedling emergence and seedling growth. The results are as follows: (1) The pH value, EC and nutrient content in interdune soil were higher than that on dune top, especially the difference of EC is five times; (2) The density of H. persicum seedlings was always higher than that of H. ammodendron during seedling growth on dune top, but the situation was contrary in the interdune lowland; total seedling densities of H. ammodendron and H. persicum were higher on their own soil type, this differed significantly among the two microhabitats. Results reveal that the regeneration capability and adaptability of H. persicum were higher than those of H. ammodendron for the barren dune top soil, but the situation was contrary for the interdune lowland; (3) Emergence rate of the two species was decreased with the increase of sand burial depth, and at the same sand burial depth, the mortality of H. persicum seedlings was lower than that of H. ammodendron. H. ammodendron emerged at sand burial depth of 0-3 cm, and its optimal burial depth was 0.5 cm. H. persicum emerged at all sand burial depths, and its optimal burial depth was 0-3 cm. Date of beginning to emerge was significantly affected by sand burial depth, and at the same sand burial depth, the emergence time of H. persicum was later than that of H. ammodendron. However, the growth rate of absolute height, biomass, shootroot ratio, shoot length and root length of H. persicum were higher than those of H. ammodendron, and the growth rate of absolute height of H. persicum was significantly affected by sand burial depth. These results reveal that the capability of enduring sand burial of H. persicum is higher than that of H. ammodendron, and H. persicum is easier to survive in severe microhabitat with sand burial and wind erosion. References | Related Articles | Metrics

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Analysis on Response of Grasslands to Climate Change and Its Spatial Difference in Xilingol League CAO Li-Guo, LIU Pu-Xing, ZHANG Ke-Xin, WANG Hong-Yan 2011, 28 (5):  789-794.  Abstract ( 1645 )   PDF (1884KB) ( 1326 )   Changes of the temperature and precipitation in Xilingol League of Inner Mongolia in the recent 51 years and the response of grassland climatic productivity to these changes were analyzed based on the meteorological data observed during the period from 1958 to 2008 using the Miami model, Thornthwaite model, Kriging interpolation and mathematical statistics method. The results revealed that the temperature increased by 2.19 ℃ in recent 51 years, its increase rate was 0.43 ℃/10 a, but precipitation decreased slightly with a decrease rate of 6.35 mm/10 a. All these revealed that climate in Xilingol League trended to be a warmingdrying pattern, and the seasonal productivity of grasslands was decreased in varying degrees. As a result, the grassland climatic productivity was inclined to decrease. There was a significant correlation between the grassland climatic productivity and the annual precipitation, and the correlation coefficient was 0.98, which suggested that water was the main factor restricting the grassland climatic productivity. The regression model is Y=169.606+7.053t+1.142r(R=0.978, P<0.01),which suggested that the annual grassland climatic productivity will be increased or decreased by 7.05 g/(m2•a) if the mean annual temperature increases or decreases by 1 ℃, and the annual grassland climatic productivity will be increased or decreased by 1.14 g/(m2•a) if the annual precipitation increases or decreases by 1 mm. References | Related Articles | Metrics

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Effect of Outersource Phosphorus Usage and Application Ways on the Contents of Available Phosphorus in Gray Desert Soil WANG Bin, ZHU Jing-Rong, XU Yong-Mei, LIU Hua, YANG Tao, MA Xing-Wang 2011, 28 (5):  795-799.  Abstract ( 1425 )   PDF (1019KB) ( 1203 )   The effect of outersource phosphorus usage and the application ways of humic acid on the content of available phosphorus in gray desert soil were studied in a laboratory. The results show that the content of soil available phosphorus was increased at first and then decreased with the increase of outersource phosphorus usage, and the soil phosphorus fixation rate was increased at first, and then decreased, but increased again with the increase of outersource phosphorus usage. There was a maximum balance point of available phosphorus in soil. The effect of application ways of outersource phosphorus and humic acid on soil available phosphorus content was significant. Soil available phosphorus content could be significantly increased by applying humic acid or outersource phosphorus. The effect of rational application of combining humic acid and outersource phosphorus on soil available phosphorus content was more significant than that by applying outersource phosphorus or humic acid only. Soil available phosphorus content could be increased most effectively by applying outersource phosphorus at first and then humic acid. Related Articles | Metrics

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Effects of Biological Soil Crusts on Seed Emergence and Seedling Growth in Loess Plateau, North Shaanxi Province WANG Rui, ZHU Qing-Ke, ZHAO Lei-Lei, CHANG Cun, MA Hao 2011, 28 (5):  800-807.  Abstract ( 1929 )   PDF (2288KB) ( 1224 )   Biological soil crusts are prevalent in arid and semiarid regions, they are the complex mixtures of cyanobacteria, green algae, phycolichens, mosses, liverworts, fungi and bacteria. In order to understand the effect of biological soil crusts (BSCs) on seed emergence and seedling growth in loess region, we conducted field surveys and studied the impact of intact crusts, broken crusts and soil on seed emergence of 4 plant species including Pinus tabulaeformis, Caragana korshinskii, Hippophae rhamnoides and Pyrus betulifolia based on the field emergence experiment in Wuqi County, Shaanxi Province during the period from July to August 2009. The results reveal that the vegetation coverage was reduced significantly with the increase of BSCs coverage and thickness (P<0.01), and vegetation types were in an increase trend (P＞0.05). Seed emergence rate and emergence process were affected by plant species and crust types (intact crusts, broken crusts and soil) (P<0.01), and the interaction between the two affected slightly the seedling emergence (P＞0.05), but affected significantly the emergence process (P<0.01). The seed emergence rate under broken BSCs was higher than that under intact BSCs, but there was no significant difference with soil. Broken BSCs could increase plant biomass and rootshoot ratio of plants, but intact BSCs affected the plant biomass and rootshoot ratio depending on the types of seed. References | Related Articles | Metrics

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Effect of Microbiotic Crust on Soil Water Infiltration in the Loess Plateau ZHANG Kan-Kan, BU Chong-Feng, GAO Guo-Xiong 2011, 28 (5):  808-812.  Abstract ( 1879 )   PDF (1200KB) ( 1335 )   In this study, the disc infiltrometers were used to measure soil water infiltration under 6 kinds of treatments (the regions where there was no microbiotic crust, there was microbiotic crust, Stipa bungeana grows, S. bungeana grows with microbiotic crust, Korshinsk peashrub grows, K. peashrub grows with microbiotic crust), and the measured data were compared and analyzed. The results are as follows: (1) Microbiotic crust impeded soil water infiltration whether there was vegetation or not, and the stable infiltration rate and cumulative infiltration were higher in the regions where there was no microbiotic crust than those in the regions where there was microbiotic crust; vegetation increased the capability of resisting soil water infiltration of microbiotic crust; (2) The fitting effect with Kostiakov model under the treatment without microbiotic crust and with S. bungeana was fine; that with Philip model under the treatments without microbiotic crust, with K. peashrub and K. peashrub with S. bungeana was fine; and that of water infiltration with Horton model under all 6 kinds of treatments was fine. Therefore, Horton model can be used to describe soil water infiltration in the Loess Plateau. References | Related Articles | Metrics

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Spatiotemporal Distribution of AM Fungi in the Rhizosphere of Artemisia ordosica and A. sphaerocephala in Desert SHAN Bao-Qin, HE Xue-Li 2011, 28 (5):  813-819.  Abstract ( 2003 )   PDF (1490KB) ( 961 )   The objective of this study is to elucidate the ecologic function of AM fungi and the interaction between sandfixation plants and AM fungi so as to provide more information for utilizing AM fungi and regenerating environment in desert regions. The study was carried out in the rhizosphere of Artemisia ordosica and A. sphaerocephala in north sandy land of Yulin city. The soil samples in profile of 50 cm in the rhizosphere of two host plants were collected at depths of 0-10, 10-20, 20-30, 30-40 and 40-50 cm in April, July and October 2007. The results show that both the host plants could form well symbionts with AM fungi in desert. The hyphal colonization of AM fungi of A. ordosica was 90.72%, that of A. sphaerocephala was 89.63%, and both of them formed the intermediate type mycorrhizas. The highest value of spore density occurred in soil layer of 0-10 cm, and the spore density was decreased with the increase of soil depth from 0 to 50 cm. The highest value of spore density occurred in July and was much higher than that in April and October, but the arbuscular colonization was reverse. Spore density of A. ordosica was significantly and positively correlated with available P, organic matter content, temperature and alkaline phosphatase. Arbuscular colonization was negatively correlated with available P, organic matter content and alkaline phosphatase. Spore density of A. scoparia was much higher than that of other two plants, but hyphal, vesiclar and arbuscular colonizations of AM fungi were much lower. References | Related Articles | Metrics

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Xeromorphic Moss, Crossidium crassinerve (Pottiaceae, Musci),a Newly Recorded Species in Shaanxi Province and Its Ecological Functions LIU Yong-Ying, BU Chong-Feng, MENG Jie, LI Min, ZHAO Jian-Cheng 2011, 28 (5):  820-825.  Abstract ( 1914 )   PDF (1158KB) ( 1029 )   As a xerophyte, Crossidium crassinerve (De Not.) Jur. is newly reported in Shaanxi Province based on the specimens collected from Shenmu County. The genus is recorded in Shaanxi Province for the first time. Its morphologic and anatomical characters are described and illustrated. Some important structures, such as cell of chlorophyllose filament on costae, peristome, basal membrane, spore, antheridium and relationship between rhizoid and sand fixation, are observed under a scanning electron microscopy. The species is one of the typical xerophytes growing in arid and semiarid areas. Moss forms gradually the following morphologic and anatomical features to adapt the extremely arid environment: plants dwarf and are in dense turfs or small cushions, have dense and branched rhizoids; stems have central strand and leaf costa with guide cells; stem leaves imbricate and are concave in distal half; upper part of the leaf margin is strongly recurved; costa excurrent is just like a long hyaline hair; filaments restrict the adaxial surface of costa; the species not only produces the sexual structure sporophyte, but also generates a lot of asexual structure gemmae in this area. The species is mainly distributed in desert, semiarid desert or hilly regions covered by sand sheet in the regions between 15°-50° N in the world. It plays the important ecological roles in sand fixation, water storage and vegetation succession. It is restricted in Inner Mongolia and Xinjiang of northwest China. The new record provides a reference for the flora in Shaanxi and even in China. References | Related Articles | Metrics

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Study on Impact of Tourist Activities on β Diversity of Mountain Meadow in the Wutai Mountain NIU Li-Qin, CHENG Zhan-Hong 2011, 28 (5):  826-831.  Abstract ( 1611 )   PDF (1316KB) ( 1067 )   Mountain meadow is a kind of special ecosystem, it is not only a kind of important scenery resources, but also has certain ecological benefits. Many scholars studied the impact of tourist activities on meadow, but these researches were not still extensive and profound. In this paper, the impact of tourist activities on β diversity of meadow is studied using 5 indices in the Wutai Mountain. The results are as follows: (1) β diversity of meadow communities is impacted by tourist disturbance and interspecies competition. There is a big change of β diversity among different communities but a small one in the same communities; (2) The change trend of five diversity indices shows that the higher the distance gradient is, the less the common species among communities are, and the high their difference is; (3) Although five β diversity indices are calculated with different ways, their results are consistent, among which the result of BrayCurtis index is more accurate and detailed. References | Related Articles | Metrics

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Ecological Adaptability of Helianthemum songaricum Roots in West Ordos QING Hua, YANG Jie, ZHANG Pu-Jin, CHEN Yu, ZHANG Lei, ZHAO Li-Qing, SONG Bing-Yu 2011, 28 (5):  832-838.  Abstract ( 1942 )   PDF (1173KB) ( 1093 )   Helianthemum songaricum, a rare and endangered shrub species in west Ordos, is tertiary relic plant, and its community is one of the major types of desert vegetation. The species plays the important roles in maintaining the stability of desert vegetation and researches for environmental evolution, flora, biological evolution and biodiversity. In this study, the roots of H. songaricum in west Ordos were excavated in growth season to investigate its morphological characteristics. Moreover, the soil mechanical composition and vertical distribution pattern of soil moisture content after effective rainfall in H. songaricum community were also investigated. The results show that the depth of the roots could reach down to about 100 cm, and the root range was more than 30 times larger than that of canopy; the root biomass and length density were mainly distributed in soil layers of 0-30 cm, which accounted for 94.51% and 90.61% of the total root biomass and total root length density, respectively. Vertically, the biomass and root length density of fine roots (＜1 mm in diameter), small roots (1-2 mm in diameter) and medium roots (2-5 mm in diameter) were all increased at first and then decreased with the increase of soil depth, and the maximum values occurred all in soil layer of 10-20 cm. Fine root biomass and root length density had a significantly positive correlation with soil water content, but not with soil mechanical composition. Compared with the contents of other soil particles, stone content was more correlated with fine root biomass, root length density and soil moisture content. Our results suggested that the formation of root morphological characteristics of H. songaricum is a result of adaptation to drought and gravel habitat. References | Related Articles | Metrics

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Ecological Adaptability of Caragana tibetica Individuals in the Ordos Plateau ZHANG Pu-Jin, YANG Jie, ZHAO Li-Qing 2011, 28 (5):  839-848.  Abstract ( 2519 )   PDF (5208KB) ( 1359 )   A peculiar ecotone forms in the arid and semiarid Ordos Plateau of China, and it provides an important habitat for diverse shrub communities that play an important role in maintaining the desert ecosystem and sustaining the local stock raising. Caragana tibetica community is a zonal vegetation type in this grasslanddesert ecotone. It occupies a largest area constituting an important rangeland and contributing to ecological stability in this region. We investigated the morphological characteristics of aboveground part of C. tibetica individuals. Underground part was studied only for the selected medium and small sized individuals. Soil moisture content inside and outside of C. tibetica nebkhas was measured, sand landforms were distributed around shrubs, and fissuration of roots and stems of C. tibetica was examined. We found that the individuals of C. tibetica were 57 cm long, 44 cm wide and 22 cm tall in average. Nebkhas were 77 cm long, 52 cm wide and 16 cm high in average, and their average volume was 0.071 m3. It was found that 18 thick stems of C. tibetica emerged from each nebkha surface in average. The length of stems buried in nebkhas varied in a range of 8-10 cm for each class with about 2/3 of them being dead. Number of stems in the lower class was 2-3 times higher than that in the higher class. Roots were stratified into two layers. In addition, stems buried in nebkhas grew adventitious roots. The rootshoot ratio varied in a range of 0.35-0.53. Generally, the soil layer of 20-60 cm in depth is characterized by small and fine roots and higher soil moisture content. Nebkhas play an important role in supporting and protecting aboveground part of C. tibetica. Stems and roots of the shrub are also characterized by the interesting phenomenon of fissuration. Our findings indicate that morphological characteristics of  C. tibetica are developed as a result of adaptability of C. tibetica to drought environment. References | Related Articles | Metrics

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Study on Phylogeny of Four Polygonaceae Genera from Arid and Semiarid Areas SUN Yan-Xia, ZHANG Ming-Li 2011, 28 (5):  849-853.  Abstract ( 1865 )   PDF (583KB) ( 1086 )   Atraphaxis, Calligonum, Parapteropyrum and Pteropyrum are all the genera of Polygonaceae distributed in arid and semiarid areas. The four genera have many similar characters in morphology. In China, Atraphaxis and Calligonum are mainly distributed in Xinjiang, and Parapteropyrum is endemic in Tibet. The genus Pteropyrum including 3-5 species can be found in Southwest Asia and Middle East. Total genomic DNA of Atraphaxis, Calligonum, Parapteropyrum and Pteropyrum was extracted from the leaves dried with silicagel or from herbaria, the polymerase chain reaction (PCR) was used to amplify the chloroplast DNA atpB-rbcL region. The atpB-rbcL , the intergenic spacer between atpB gene and rbcL gene, about 900 bp in length, is widely used for the phylogenetic analysis on generic level. The phylogenetic tree based on the atpB-rbcL sequences reveals that Calligonum shows closer relation to Pteropyrum, additionally, Parapteropyrum is out of the clade including Calligonum, Pteropyrum and Atraphaxis.Within Calligonum,Section Calligonum, Section Medusa and Section Pterococcus formed a small clade, which is distinct from Section Calliphysa. References | Related Articles | Metrics

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Study on Geographic Distribution of Endemic Plant Species in Xinjiang CHENG Yun, YUAN Lei 2011, 28 (5):  854-859.  Abstract ( 4451 )   PDF (918KB) ( 1999 )   The study shows that there are 271 endemic plant species in 119 genera of 38 families in Xinjiang. Under effects of the peculiar landforms of “two basins between three mountains” and the climatic conditions, the endemic plant species are more in the mountains where precipitation is high than those in plains and deserts. The endemic plant species are mainly distributed in the valley in the Tianshan Mountains, Altay Mountains, Kunlun Mountains and Pamirs. The endemic plant species are less in the Tarim Basin and TurpanHami Basin in south Xinjiang due to the severe natural environment; climatic conditions and the flora origin in the Junggar Basin are peculiar in arid northwest China, there are 118 endemic plant species, and they occupy 43.54% of the total in Xinjiang. Geographic distribution of endemic plant species in Xinjiang is analyzed, the formation causes are researched, and it is put forward that the conservation of endemic plant species is important for maintaining the biodiversity in Xinjiang. The results can be referred in further study on floras in Xinjiang.   References | Related Articles | Metrics

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Response of Water Resources in the Yellow River Basin to Global Climate Change LIU Ji-Feng, WANG Jin-Hua, JIAO Min-Hui, ZHANG Rong-Gang 2011, 28 (5):  860-865.  Abstract ( 2017 )   PDF (1500KB) ( 1110 )   The Yellow River Basin is located in arid and semiarid regions of China, where water resources system is very sensitive to climate change. Temperature and precipitation in the Yellow River Basin have changed obviously in recent decades. Since the mid1980s, temperature has been significantly increased, especially in winter temporally and in the north of the basin spatially. In the 1990s, precipitation in the Yellow River Basin was decreased apparently, and it has been slightly increased in 21st century. Climate warming and precipitation decrease were the important causes resulting in a sharp reduction of runoff volume in the Yellow River Basin. According to the predicted results with climate change model, the temperature would apparently increase and precipitation would have a slightly increment in 2050, which will aggravate the contradiction between demand and supply of water resources in the Yellow River Basin. Therefore, some adaptive measures should be taken so as to reduce the negative effects of climate change on water resources in the Yellow River Basin. References | Related Articles | Metrics

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Change of Heavy Precipitation Days in Shaanxi Province YANG Wen-Feng, GUO Da-Mei 2011, 28 (5):  866-870.  Abstract ( 1351 )   PDF (1298KB) ( 963 )   In this paper, statistical methods, such as the quartic polynomial, maximum entropy spectral analysis and MannKendall test, are used to analyze the daily precipitation data observed by 78 selected meteorological stations distributed evenly in Shaanxi Province during the period from 1961 to 2004, and the heavy precipitation days are acquired by defining heavy precipitation. The results show that the variability of heavy precipitation days was high, and drought and flood occurred easily in Shaanxi Province. The heavy precipitation days was increased after the end1990s. Under the reliability level of α=0.1， a sharp decrease of heavy precipitation days occurred during the period from the end1980s to the early1990s. Heavy precipitation days were increased from the north to the south, and there were two centers with more heavy precipitation days: one was near Yijun, and the other was near Zhenba. The daily maximum precipitation in the Guangzhong region was in an increase trend in recent 40 years, and it was increased by 1.5 mm every ten years. The intensity of heavy precipitation was also increased. References | Related Articles | Metrics

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Comprehensive Analysis on a Durative Regional Haze and Fog ZHAO Gui-Xiang, DU Li, WEI Li-Ping, HE Yao-Wu, LI Ying, ZHU Yu 2011, 28 (5):  871-878.  Abstract ( 2055 )   PDF (1881KB) ( 1355 )   A durative regional haze and fog weather occurred in Shanxi Province in November 1994 was comprehensively analyzed based on the observed data. The results are as follows: (1) Front area at 500 hPa was located by north, circulation at midlatitude was straight, and there was a warm advection at 850 hPa to convey continually towards Shanxi. These were the important weather background to form a largescale haze. While blocking situation at 500 hPa maintained stably and the surface refluence was stable to form the largescale fog; (2) Change of relative humidity at 850 hPa was the basic criterion of judging the formation of haze and fog; sustained existence of temperature inversion layer was the important reason for haze and fog; differences of humidity and intensity of temperature inversion layer were the criteria of judging the largescale haze and fog; (3) There was a wholelayer negative vorticity advection, but a weak reversion occurred at 1 000-925 hPa, and it was a dynamic factor for haze; there was a negative vorticity advection near ground surface but a positive one above 925 hPa, or there was a wholelayer positive one, which was the dynamic structure for fog; (4) The total temperature advection diagnosis reveals that there was a warmdry advection conveying to Shanxi before haze but a warmmoisture advection or a coldmoisture conveying to Shanxi before fog. The total temperature advection of haze was larger than that of fog, but the contribution of each component to the total temperature advection was different; (5) The occurring time and duration of haze and fog were quite different, and the meteorological factors were quite different before and after haze and fog occurred. All these could provide the references for forecasting haze and fog weather. References | Related Articles | Metrics

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Study on Statistical Downscaling of Air Temperature in West China CHAO Zhen-Hua 2011, 28 (5):  879-884.  Abstract ( 1955 )   PDF (2569KB) ( 1264 )   Driving data, such as air temperature, precipitation, wind field, specific humidity and radiation, used in land surface models and land data assimilation system, can be derived using the reanalysis datasets from downscaling. In this study, the statistical downscaling of air temperature data was analyzed based on calculating the observation error covariance in west China using geostatistics, estimating the background error covariance using innovation vector method, and interpolating the daily air temperature data with spatial resolution 0.125°×0.125° in 2000 using optimal interpolation, and the precision of the analyzed air temperature field was also analyzed. The results show that the analyzed daily air temperature can well reflect the change of air temperature in west China and be directly used in land surface models under the gentle topographical conditions. For the QinghaiTibetan Plateau, however, quality of the analyzed air temperature was poor due to the effect of the topography and distribution of weather stations, but it was increased to some extent compared with the reanalyzed data. References | Related Articles | Metrics

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Study on Climatic Characteristics of Low Temperature in the East Hexi Corridor and Forecast Method DING Wen-Kui, YANG Xiao-Ling, YANG Jin-Hu, ZHOU Wen-Xia 2011, 28 (5):  885-890.  Abstract ( 2369 )   PDF (1399KB) ( 1177 )   In this study, the spatiotemporal distribution, intensity and duration of low temperature in Wuwei in the east Hexi Corridor during the period of 1960-2009 were systematically analyzed using low temperature data (the lowest temperature ≤-20 ℃) observed by 5 meteorological stations. The results show that low temperature occurrence was regional, and low temperature days in high mountains and the marginal zone of north desert were obviously more than those in oases. Days and intensity of low temperature were significantly decreased with climate warming. Low temperature occurred mainly in January, February and December. Proportion of low temperature duration more than 2 days varied in a range of 41.4%-64.4% of the total, and severe low temperature occurred in low temperature process. The factors were initially elected with Press criterion and chosen with stepwise regression forecast method by selecting the ECMWF grid field data in January, February, November and December during the period of 2003-2007, the equations were developed with the optimal subset regression for forecasting the minimum temperature in January, February, November and December. The optimal significance equations for forecasting the minimum temperature were determined with the CSC double grading criterion, and the forecast equations passed through a significance test at level of  α=0.01. Back substitution fitting rate of the prognostic equations varied in a range of 70.7%-76.5%, and the forecast accuracy rate was in a range of 63.5%-68.9%. An objective and effective instruction product was provided for forecasting low temperature. Forecast marginal value and forecast rank of low temperature were determined with the highest approach principle. References | Related Articles | Metrics

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Experimental Study on Ensemble Forecast in Forecasting Heavy Rainfall in Xinjiang JIA Li-Hong, TANG Hao, WANG Jiang, ZHANG Yun-Hui 2011, 28 (5):  891-895.  Abstract ( 1800 )   PDF (1956KB) ( 1497 )   Based on the mesoscale model GRAPES and WRF with multiple physical parameterization schemes and cumulus parameterization schemes, an ensemble forecast system is developed with eight combinational schemes after carrying out the sensitivity experiments. Twenty sever precipitation synoptic processes in Xinjiang in 2007 and 2008 were simulated using the ensemble forecast system, and the forecast of 24hour precipitation was tested with Ts and BS. The results reveal that the score of ensemble forecast in forecasting heavy precipitation in Xinjiang was high, the forecasted precipitation was higher than the observed precipitation, but the forecasted precipitation with ensemble forecast was lower than that with control forecast, and it was closer to the observed one. The effect of precipitation of ensemble forecast in 24 hours is superior to the others. References | Related Articles | Metrics

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Study on Quantitative Models of Concentrations of Air Pollutants over Urumqi WEI Jiang, WANG Guo-Hua, REN Quan, LIU Zhi-Hui 2011, 28 (5):  896-900.  Abstract ( 2671 )   PDF (517KB) ( 1989 )   The relationships among monthly average concentrations of air pollutants (SO2, NO2 and PM10) over Urumqi and the monthly coal consumption, inversion layer thickness and monthly average wind speed were investigated. It was found that coal consumption and inversion layer thickness were the dominant factors affecting the diffusion of air pollutants over Urumqi. Based on these analyses, the regression models were developed to describe the effects of coal consumption, inversion layer thickness and wind speed on the concentrations of air pollutants. It was concluded that the effect of inversion layer thickness on different pollutants was different, and wind speed played more important role in diffusion of air pollutants during heating period than during nonheating period. References | Related Articles | Metrics