Table of Content

25 February 2011, Volume 28 Issue 1    Next Issue

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Distribution Patterns of the Species Richness of Plants and Animals in Xinjiang,China LI Li-ping, YIN Lin-ke, TANG Zhi-yao 2011, 28 (1):  1-9.  Abstract ( 2317 )   PDF (749KB) ( 1724 )   There are 3 637 wild vascular plants, 425 birds and 154 mammals in Xinjiang. In this study, a database of the distribution of all the plants, birds and mammals in Xinjiang was compiled, the distribution maps of the species richness of plants and animals were charted, the relations between these species were analyzed, and distribution hotspots of the species richness were obtained. The results revealed that the species richness in the northern and western parts of Xinjiang was higher than that in the southern and eastern parts. There were positive correlations of the richness among the vascular plants, halophytes, ephemeral plants, endemic plants and key protective plants, and there were also positive correlation between the richness of vascular plants and that of birds and mammals. Hotspots of different taxonomic groups were incongruent. Hotspots of vascular plants were distributed in the western part of the Altay Mountains, the western and central parts of the Tianshan Mountains, and the mountains in the west Junggar Basin; those of birds extended as far as the east Tianshan Mountains and the southern slope of the west Tianshan Mountains; and those of mammals were distributed only in the Altay Mountains and the west Tianshan Mountains. Altogether only 8.9% of the hotspots were shared by all the three groups. Current nature reserve networks cover the most of these hotspots. However, the Shawan-Manas region is an important conservation gap for biodiversity in Xinjiang. References | Related Articles | Metrics

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NDVI-based Interannual and Seasonal Variations of Vegetation Activity in Xinjiang during the Period of 1982-2006 ZHAO Xia, TAN Kun, FANG Jing-yun 2011, 28 (1):  10-16.  Abstract ( 2164 )   PDF (845KB) ( 1189 )   Interannual and seasonal variations of vegetation activity in Xinjiang during the period from 1982 to 2006 were studied using the time series data of normalized difference vegetation index (NDVI) derived from remote sensing images (NOAA/AVHRR), information of vegetation distribution and observed climatic data. The results show that the NDVI in growth season (from April to October) increased significantly in 27% of the study area but decreased in 4% of the study area in recent 25 years. The area with a high NDVI (>0.3) in growth season was enlarged by 5% during the period of 2002-2006 compared with that in the 1980s (1982-1986), and the area with a low NDVI (<0.1) in growth season was reduced by 5%. Seasonal NDVI in Xinjiang increased significantly in spring, summer and autumn in recent 25 years. Seasonal variation of NDVI reveals that the NDVI increase in autumn was the most significant (P<0.01), and the mean increase rate was 0.57%. However, the seasonal NDVI varied from different vegetation types. NDVI of grasslands and desert vegetation increased significantly in spring, summer and autumn, that of crops increased significantly in summer and autumn, especially in summer (increased by 1%/a), but that of forests increased significantly only in autumn. Therefore, our study suggests that the overtime of growth season and acceleration of plant growth were the main factors resulting in the increase of vegetation activity in Xinjiang, and the increase of temperature, rainfall in summer and agricultural practices might be the important driving factors. References | Related Articles | Metrics

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Dynamic Change of Forests in Xinjiang in Recent 25 Years SHI Lei 2011, 28 (1):  17-24.  Abstract ( 1891 )   PDF (792KB) ( 1329 )   Four types of forests (i.e., deciduous coniferous forest, evergreen coniferous forest, deciduous broadleaved forest and shrub) are distributed in Xinjiang. Forest coverage is only 2% of vegetation area, but the forests play an important role in social effects, economic returns and ecological benefits. The forests in Xinjiang were firstly classified with an expert classification method based on the seasonal change of NDVI curves of the forest types and the GIMMS NDVI datasets during the periods of 1982-1984, 1984-1988, 1989-1993, 1994-1998, 1999-2003 and 2004-2006, and then the changes of area, growing stock volume and density of the forests as well as their affecting factors were analyzed. The results show that the forest area and the growing stock volume were increased by 5.83×105 hm2 and 4.02×107 m3 in recent 25 years respectively, and the forest density was increased with an annual increase rate of 0.019%, indicating that the forests in Xinjiang were developed in a virtuous circle. Moreover, the forest density of deciduous broadleaved forests was decreased with an annual change rate of -0.62%, while the growing stock volume of deciduous broadleaved forests was increased because of the enlargement of plantation area. Therefore, both afforestation and reforestation can significantly contribute to the conservation of ecological environment in arid Xinjiang. References | Related Articles | Metrics

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Distribution Patterns and Climatic Explanations of Species Richness of Vascular Plants in Xinjiang,China LI Li-ping, Nurbay Abdusalih, WANG Shao-peng, WANG Zhi-heng, TANG Zhi-yao 2011, 28 (1):  25-30.  Abstract ( 2113 )   PDF (529KB) ( 1463 )   Distribution patterns of biodiversity at large scale and their affecting factors are one of the focal issues of ecology. Xinjiang is located in an extremely arid area in northwest China, where there are ideal places to explore the distribution patterns of species richness and their affecting factors under extreme conditions because of the complicated topographical and climatic conditions and the diversity of habitats. In this study, the relationships between the distribution patterns of species richness of vascular plants and the climatic factors in Xinjiang are analyzed based on the available data of vascular plants and climatic factors. The results reveal that the species richness increases with the increase of annual precipitation (AP) and actual evapotranspiration (AET), and the curve of species richness of vascular plants with the increase of MAT and PET is unimodal. In all the subregions, species richness increases significantly with AP. Species richness patterns with the increase of MAT are different in the mountains and basins, it increases at first and then decreases with the increase of MAT in mountains, but decreases monotonically in the basins. At different water deficit (WD) levels, the increase rate of species richness is decreased with the increase of AP at high WD. Species richness increases with the increase of MAT at low WD level but decreases at high WD level. Related Articles | Metrics

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Community Structure and Its Affecting Factors of Mountain Coniferous Forests in Xinjiang,China LI Li-ping, LIU Yi-ning, TANG Zhi-yao, GUO Zhao-di, FANG Jing-yun 2011, 28 (1):  31-39.  Abstract ( 3208 )   PDF (747KB) ( 2170 )   Spatial distribution patterns and environmental factors of forests are one of the primary topics of forest ecology. In this paper, the patterns and affecting factors of community structure of mountain coniferous forests in Xinjiang are explored after carrying out the survey of 120 plots of 11 locations in the Altay Mountains (Altay), northern slope of the Tianshan Mountains (NT in abbreviation, the same below), southern slope of the Tianshan Mountains (ST) and the Kunlun Mountains (KL). The results show that the mean stem height (Hm), maximum stem height (Hmax), mean stem diameter at breast height (DBHm), maximum stem diameter at breast height (DBHmax), total basal area (TBA) and stem volume of coniferous forests were the highest in NT, followed by Altay, ST and KL. There was no significant difference of stem density among the four regions. Among different forest types, community structure characteristics of Juniperus centrasiatica and J. jarkendensis forests were all lower significantly than those of other forests. In Xinjiang, Hm, Hmax, DBHm and TBA of mountain coniferous forests decreased significantly with the increase of altitude and mean annual temperature (MAT), but increased significantly with the increase of annual precipitation (AP). A general linear model (GLM) indicated that AP, aspect and moisture of plots were the most important factors affecting community structure of these coniferous forests in Xinjiang. References | Related Articles | Metrics

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Study on Plant Species Composition and Richness of the Mountain Coniferous Forests in Xinjiang LI Li-ping, Anwar Mohammat, GUO Zhao-di, HAI Ying, TANG Zhi-yao 2011, 28 (1):  40-46.  Abstract ( 2228 )   PDF (453KB) ( 1361 )   After carrying out the survey of 122 plots at 11 locations in the Altay Mountains (Altay), Kunlun Mountains (KL in abbreviation, the same below), and northern and southern slopes of the Tianshan Mountains (NT and ST respectively) in Xinjiang, it is found that the plant species richness of coniferous forests in Altay is significantly higher than that in ST and KL; plant species richness of Picea schrenkiana forests is significantly lower than that of P. obovata forests. According to the Sorensen Index, the plant composition in ST and KL is similar, and it is also similar in Altay and NT; the plant composition in Larix sibirica forests and Picea obovata forests are similar, but that in Juniperus centrasiatica and J. jarkendensis forests is quite different from that in Pinus sibirica and Abies sibirica forests, L. sibirica forests and Picea obovata forests. Species richness decreases significantly with the increase of altitude and mean annual temperature (MAT) but increases significantly with the increase of latitudes in whole Xinjiang. Species richness decreases with the increase of total basal area (TBA) in Altay and KL. According to the GLM (General Linear Model), aspect of plots (ASP) affects significantly the plant species richness in whole Xinjiang. Forest type and TBA also affects significantly the plant species richness in north Xinjiang. While in south Xinjiang, the plant species richness is significantly affected by annual precipitation (AP), slope position (POS) and TBA. References | Related Articles | Metrics

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Study on Relationship between Height and DBH of Mountain Coniferous Forests in Xinjiang LI Li-ping, Anwar Mohammat, WANG Xiang-ping 2011, 28 (1):  47-53.  Abstract ( 2802 )   PDF (466KB) ( 2006 )   Growth of trees includes two dimensions, i.e. diameter and height. The height-diameter relationship is affected by climatic and topographic conditions as well as species properties. In this paper, the relationship between stem diameter at breast height (DBH) and stem height (H) of coniferous forests is analyzed based on 120 sample plots investigated from 11 locations in the Altay Mountains (Altay), Kunlun Mountains (KL in abbreviation, the same below), and northern and southern slopes of the Tianshan Mountains (NT and ST respectively) in Xinjiang. The potential heights (H*) of trees in each plot were estimated. The results show that the taper of coniferous forests in KL, calculated with DBH/H, is higher than that in other regions, and the potential height in KL is lower than that in Altay and NT. For different forests, the taper of Pinus sibirica, Abies sibirica and Picea obovata forests is lower than that of Larix sibirica and Juniperus forests. The taper of Picea schrenkiana forests is lower than that of Juniperus forests but higher than that of Picea obovata forests. The H* of Juniperus forests is lower than that of other forests. Taper increases with the increase of altitude but decreases with the increase of AP in whole Xinjiang. For different regions, taper increases but H* decreases with the increase of altitude in Altay and NT, but there is no notable change of taper and H* with the increase of altitude in ST and KL. For different forests, the taper and H* of L. sibirica and Picea schrenkiana forests increase and decrease significantly with the increase of altitude separately. The taper of Pinus sibirica and A. sibirica forests increases significantly with the increase of altitude. According to the GLM (General Linear Model) analysis, change of the height-diameter relationship with environmental factors is different from different regions and scales. Annual precipitation (AP), aspect of sample plots (ASP) and forest type are the most important variables to taper and H* in whole Xinjiang. ASP, slope position (POS) and mean annual temperature (MAT) are important in north Xinjiang, and ASP, AP and MAT are important in south Xinjiang. References | Related Articles | Metrics

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Study on Species-area Relationships in the Southern and Northern Slopes of the Tianshan Mountains QIAO Xiu-juan, TANG Zhi-yao, Anwar Mohammat, FANG Jing-yun 2011, 28 (1):  54-59.  Abstract ( 1956 )   PDF (445KB) ( 1176 )   Species-area relationships (SARs) were discussed in the past decades, and they were supposed to be one of the few "genuine law" in ecology. Xinjiang is located in the hinterland of the Eurasia, where there is a high radiation but a low precipitation. In this study, the patterns and mechanisms of SARs in different arid vegetation types in the Tianshan Mountains were explored by investigating sample plots. The species-area curves of steppe, meadow and desert were charted based on 26 nested sample plots, the minimum area of each nested sample plot was 0.25 m2, and the maximum one was 400 m2. All species in each sub-plot were recorded to develop SARs. The logarithmic form power curve (S = c·Az) was applied to fit SARs, and then SARs from different areas were compared with climatic variables by plotting the slope (z value) and intercept (c value) to explore the main factors affecting the patterns of SARs in Xinjiang. The power-law model was used to explain 0.90 ± 0.01 of variance of species richness at different scales. The average value of overall slope was 0.20±0.02, lower than the mean of the world. The slopes of steppe and meadow were 0.13±0.01 and 0.14±0.02 respectively. There was no significant difference between the two vegetation types. However, these two figures were significantly lower than that of desert (0.28±0.02). The climatic variables were classified into three groups: energy, water and climatic stability. In the full climatic models, all the factors were used to explain 80.42% of z value and 91.90% of c value respectively. In all the three factors, water factor was the most important for SARs, and the R2 values of z and c were 69.88% and 66.22% respectively. However, the effects of water factor on z value and c value were quite different, and z value was decreased but c value was increased with the increase of water factor. Similarly, z value was decreased but c value was increased with the increase of species richness. The results reveal that water was the main factor affecting the species-area relationship in this area, and the species richness also played an important role. References | Related Articles | Metrics

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Community Structure and Conservation of Wild Fruit Forests in the Ili Valley,Xinjiang LI Li-ping, HAI Ying, Anwar Mohammat, TANG Zhi-yao, FANG Jing-yun 2011, 28 (1):  60-66.  Abstract ( 2575 )   PDF (443KB) ( 1697 )   Ili Valley in Xinjiang is one of the distribution centers of wild fruit species in the world. In this study, the species richness and structure of wild fruit forests in the Ili Valley were analyzed based on the investigated data from 67 sample plots. The results show that Juglans regia, Malus sieversii, Armeniaca vulgaris and Prunus sogdiana forests are the main wild fruit forests in the Ili Valley. In total, 207 species in 141 genera and 46 families have been recorded. Species richness is higher in the A. vulgaris and P. sogdiana forests than that in the J. regia and M. sieversii forests. Stem density of the M. sieversii forests is significantly higher than that of the A. vulgaris forests. Mean stem height (Hm) of the J. regia forests is higher than that of the P. sogdiana forests. There is no significant difference in mean stem diameter at breast height (Dm) among the four forest types. Species richness tends to decrease, whereas Hm and Dm tend to increase, and there is no significant change of stem density with the increase of altitude. The results of a canonical correspondence analysis (CCA) reveal that the J. regia forests are mainly distributed in the warm areas, whereas the M. sieversii forests in the cold regions, and the A. vulgaris forests widely across the Ili Valley. Compared with other three forest types, P. sogdiana forests are only distributed in the mountainous areas in Huocheng County, where water availability is relatively high. The wild fruit forests in the Ili Valley are suffering from the severe destruction due to the intensive human activities, and they should be protected in some ways, such as the collection of germplasm resources and ex-situ conservation. References | Related Articles | Metrics

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Formation,Distribution and Transport of Shallow Groundwater in Arid Areas,China ZHANG Hong-yi, ZENG Fan-jiang, AN Hai-tang 2011, 28 (1):  67-73.  Abstract ( 2063 )   PDF (763KB) ( 1872 )   Formation of shallow groundwater is an inter-transform process of precipitation, surface water and groundwater. Formation of shallow groundwater in the arid areas in China, where shallow groundwater relies mainly on runoff from the debouchures of rivers, is quite different from that in the humid regions in east China and the high-cold Qinghai-Tibetan Plateau. The studies reveal that mountainous groundwater is mainly recharged by rainfall (or glacial-snow melt water) permeation in the arid areas in China. Rainfall recharges rivers after it is transformed as surface water, and also plays a certain role in the formation process of shallow groundwater in the plain basins. Shallow groundwater in the plain basins is mainly recharged by surface runoff permeation downstream from the debouchures. Groundwater and surface water is from the mountainous regions. Affected by geologic and geomorphologic conditions, the multiple transform processes of groundwater and surface water in the plain basins provide the advantages for utilizing groundwater and the favorite conditions for improving the local social and economic development and people's life. References | Related Articles | Metrics

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Field Experimental Study on Infiltration in Seasonal River Channels WU Gui-zhi, ZHENG Xi-lai, LIN Guo-qing, HAO Peng 2011, 28 (1):  74-78.  Abstract ( 1790 )   PDF (404KB) ( 1097 )   In order to find the leaking laws of seasonal Dagu River in Shandong Province, some typical test sited were established in the upper and middle reaches of the Dagu River, and the field infiltration experiments were conduced based on the theory of water movement in vadose zone. Capacities of infiltration in riverbed in different vadose zones were studied. The results show that the infiltration process in the dry riverbed could be divided into two stages, i.e. the unstable infiltration and stable infiltration; the infiltration in the riverbed was affected by the hydraulic properties of vadose zone, and the infiltration rate in the upper reaches was higher than that in the middle reaches. The stable infiltration rates in the upper and middle reaches were 0.028 and 0.023 cm/s respectively. The process of unstable infiltration varied in a range of 1.5-2.0 hours, the proportion of infiltration was low in the total leakage, and it was gradually decreased with the time. Therefore, it is feasible to calculate the total leakage by using the stable infiltration rate in riverbed in flood season. References | Related Articles | Metrics

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Effects of Drip Irrigation Volume on Soil Water-salt Transfer and Its Redistribution Su Litan, Abudu Shalamu, SONG Yu-dong 2011, 28 (1):  79-84.  Abstract ( 2045 )   PDF (496KB) ( 1400 )   Because of the irrigation regime and natural factors, soil salinazation has become more and more severe in arid regions. A 3-year field experiment was carried out to investigate the effects of different drip irrigation regimes on soil salinity distribution and cotton yield at Aksu National Station for Farmland Ecosystem Scientific Research, Chinese Academy of Sciences. The results show that the distribution of soil salinity was affected by the redistribution of soil moisture content. Average soil moisture content was gradually increased in cotton growth season. The position of peak value of soil salinity under mulch was moved downward with the increases of drip irrigation volume, and it was moved vertically from 35 cm to 65 cm when the drip irrigation volume was increased from 3 000 m3/hm2 to 4 800 m3/hm2. The downward movement of the position of peak value of soil salinity under mulch was in an order of the treatment Ⅳ > treatment Ⅲ > treatment Ⅱ > treatment Ⅰ after irrigation, which reveals that the increase of drip irrigation volume could promote soil desalinization. Soil salinity was moved gradually from deep soil to topsoil and from the soil layer under mulch to the inter-mulch soil layer simultaneously. With the increase of drip irrigation volume, the average soil salt content was decreased in rhizosphere (0-40 cm in depth) at the end of experiment. The soil desalinization rates of the treatment Ⅰ, treatment Ⅱ, treatment Ⅲ and treatment Ⅳ were 2.5%, 7.7%, 9.7% and 15.8% respectively. Compared with the soil salinity in soil layer of 0-40 cm in depth, the average soil salt contents for all the treatments were increased in soil layer of 0-100 cm at the end of experiment, they were increased by 0.4 dS/m, 0.3 dS/m, 0.3 dS/m and 0.1 dS/m for the treatment Ⅰ, treatment Ⅱ, treatment Ⅲ and treatment Ⅳ, and their salinization rates were 9.3%, 6.8%, 6.7% and 2.6%, respectively. Therefore, high drip irrigation volume of 4 800 m3/hm2 could be the most suitable drip irrigation regime for leaching soil salinity under drip irrigation in silt loam soil in arid regions. References | Related Articles | Metrics

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Analysis on Soil Moisture Content in the Middle Reaches of the Yellow River LI Run-chun, ZHANG Xiu-zhi, WANG Li-hua, LV Xin-yan, GAO Yuan 2011, 28 (1):  85-91.  Abstract ( 1812 )   PDF (779KB) ( 1348 )   In this paper, the data of soil moisture content in the middle reaches of the Yellow River during the period of 1981-2002 were analyzed to find the horizontal and vertical distribution laws. Characteristics of interannual and inter-decadal change of soil moisture content were also analyzed. The results reveal that, horizontally, soil moisture content was approximately higher in the central part than that in the southwestern and southeastern parts of the study area. Vertical distribution of soil moisture content changed seasonally. Soil moisture content was sharply decreased from early spring to May, especially in topsoil, the time when soil became the driest was earlier for 3 ten-day periods than that in soil layer of 50-100 cm, and the upper soil layer was drier than the lower one. Moisture content in topsoil was sharply increased in rainy season, and it was higher than that in lower layer. Holistically, soil moisture content was in a decrease trend, and there was a 5-6-year periodic change in the study area during the period of 1981-1996. There was an abrupt change of soil moisture content around 1991 in the central-southern part. Soil moisture content and its interannual change extent were high before 1991, and then soil became drier and the interannual change extent was lower. The change of soil moisture content was the most remarkable in the central-southern part of the study area. References | Related Articles | Metrics

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Study on Land Use Structure in Zhangye City Base on Information Entropy and Grey Prediction WANG Xiao-jiao, CHEN Ying, QI Peng, ZHANG Ren-zhi 2011, 28 (1):  92-97.  Abstract ( 1927 )   PDF (414KB) ( 1313 )   This paper analyzes the dynamic variation of information entropy of land use structure in Zhangye City, Gansu Province during the period 2003-2007 based on Shannon information entropy, makes a preliminary discussion on the land use types affecting the values of information entropy, and predicts the information entropy in the city during the period from 2008 to 2015 using the GM (1, 1) model of grey system theory. The results show that, firstly, the main land use types affecting the dynamic variation of the information entropy of land use structure in the city were the grassplots, other farming lands, residential areas, lands for industry, mining and traffic as well as unused land, among which there was the closest correlation between the dynamic variation of information entropy of land use structure and the grassplots. Secondly, the information entropy and the equilibrium degree of land use structure in Zhangye City were monotonically increased, but the increase trend was gradually slowed down, which reveals that the land use structure was become more and more balanced with the economic development. References | Related Articles | Metrics

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Study on the Flora in Xarxili Nature Reserve in Xinjiang HAI Ying, YAO Jian-bao, Bingbujiafu, Dilimulat Yusufu, ZENG Ya-juan 2011, 28 (1):  98-103.  Abstract ( 1598 )   PDF (360KB) ( 1390 )   The Xarxili Nature Reserve (45°07'43″-45°23'15″N, 81°43'09″-82°33'18″E) is located in the southern piedmont of the Alataw Mountain in Xinjiang, its western part borders on the Republic of Kazakhstan, and its area is 314 km2. Since the ancient times, this area has been the territory of China. It was forcibly occupied by the former Soviet Union before the 1960s, and it was a disputed area between China and the former Soviet Union due to a series of unfair treaties imposed by tsarist Russia. After the disintegration of the former Soviet Union, the area became as a disputed area between China and the Republic of Kazakhstan. A series of agreements and joint communiqués were signed after carrying out the equal and friendly consultations between the two countries in the 1990s, and then the new national boundaries and boundary lines in the disputed area were delimited. As a result, the Xarxili Nature Reserve returned to China in 1999. After carrying out on-the-spot investigations, it has been found that there are 1 680 species of vascular plants (including the subspecies and variants) in 517 genera and 81 families, among which there are 23 species in 14 genera and 9 families of fern, 9 species in 3 genera and 3 families of gymnosperm, and 1 648 species in 500 genera and 69 families of angiosperm. Analysis of distribution patterns of the genera and species reveals that the proportions of the north-temperate-zone distribution pattern and its variants, temperate distribution pattern of the Old World and its variants are the highest because of the geographical location and the temperate features of the flora in this area. The proportions of the Mediterranean and West Asian-Central Asian distribution patterns and their variants are the second highest, and the proportions of the temperate Asian and tropical distribution patterns are the third highest. The proportions of East-Asian distribution pattern and its variants and the North-American discontinuous distribution pattern are the lowest. These reveal that there are the most interflows between the flora in this area and that in the Old World temperate zone, Mediterranean and Western Asia-Central Asia, there are also certain interflows with the temperate Asian and tropical flora, and the interflows with the East Asian and North American flora are the lowest. References | Related Articles | Metrics

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Conservation Biological Study on Eremosparton songoricum ZHANG Dao-yuan, LIU Hui-liang, WANG Jian-cheng, SHI Xiang, LIU Yan 2011, 28 (1):  104-110.  Abstract ( 1610 )   PDF (376KB) ( 1570 )   Rare species and their conservation in severe ecosystems have attracted more and more attention in recent years. Eremosparton songoricum (Litv.) Vass. is a rare woody shrub distributed in the mobile-dune areas in the Gurbantonggut Desert, Xinjiang, China. A conservation biological study on E. songoricum was carried out to examine the threatened ecological process and characteristics during the period from 2003 to 2009.The paper reviewed thoroughly the biological characteristics of tendency to rare status, geographic distribution, habitat conditions, population dynamics, features of sexual reproduction and asexual propagation, and genetic diversity and variation. In addition, some strategies and measures were put forward for conserving E. songoricum. References | Related Articles | Metrics

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Structure and Dynamic Change of Natural Pinus tabulaeformis Populations in the Ziwuling Forested Area CUI Chang-mei, WANG Xiao-an, GUO Hua, LI Wei 2011, 28 (1):  111-117.  Abstract ( 1762 )   PDF (479KB) ( 1132 )   Pinus tabulaeformis is an important endemic species in the Loess Plateau, and it has a pivotal role in improving local ecological environment. In this paper, the types of P. tabulaeformis population structure were analyzed with sampling method. The laws of dynamic change of P. tabulaeformis population were analyzed using the static life table and survival curve. The results show that the P. tabulaeformis populations were in an inversed J-shaped distribution, and their age structure belonged to a typical growth type. The height structure was in a reverse pyramid-like form, most trees were 2-6 and 8-14 m high (76.4%), the tree number was decreased with the increase of crown size, and the proportion of the trees with crown size smaller than 6 m2 was 85.5%. There was a close correlation between the tree height and DBH, and the correlation between the crown size and DBH was closer than that between tree height and crown size. Mortality of both seedlings and saplings was low, and the survival curves of P. tabulaeformis populations were between Deevey Ⅱ and Deevey Ⅲ. According to the structure and dynamic laws of P. tabulaeformis populations, it can create more economic returns and ecological benefits to take the suitable artificial rearing and conserving measures. References | Related Articles | Metrics

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Relationship between Species Diversity of Herbaceous Plants in the Shelterbelt and Environment Factors ZHANG Jia, LI Sheng-yu, JIN Zheng-zhong, LEI Jia-qiang 2011, 28 (1):  118-125.  Abstract ( 2007 )   PDF (442KB) ( 1219 )   Many researchers have focused on the close relationship between species diversity and ecosystem stability. The Taklimakan Desert is a mobile desert with various dunes. Climate in the desert is characterized by the extreme aridity, low vegetation coverage and a few survival salt-tolerant desert plants. So, herbaceous plants grow only in the bottom of dunes under the conditions of high temperature, drought and high saline environment. As the longest desert highway in the world, the Tarim Desert Highway in Xinjiang of China is 436 km in length and covers an area of 3 128 hm2. The shelterbelt along the highway with average width of 2-6 km is irrigated with salty groundwater. Shrubs of the shelterbelt are Haloxylon, Tamarix and Calligonum plants. Herbaceous plant species have been notably increased since the shelterbelt was planted, and the herbaceous plant coverage has been over 40% along some highway sections. A stable windbreak and sand-fixation system has been formed by the shrub layer and herbaceous plant layer. Previous researches focused on sand-fixing efficiency, micro-climate benefits, physical and chemical properties of soil, changes of plant growth and transpiration along the shelterbelt in the Taklimakan Desert. To date, there are no the papers focusing on the change of species diversity of the artificial ecosystem yet. In this paper, the spatial differentiation of herbaceous plants is researched, and the relationship between species diversity and environmental factors is analyzed. In the study, 10 sample plots were delimited along the Tarim Desert Highway shelterbelt, 3 sample lines, 100 m in length and perpendicular to the highway, were set in each sample plot, and 10 to 14 sub-plots (5 m×5 m) were delimited between the sample lines. Number, coverage and richness of herbaceous plants and corresponding environment factors, such as groundwater level, groundwater electrical conductivity and mineralization, soil electrical conductivity, average range of tree crown of shrub layer and shade density, were recorded and surveyed comprehensively. Sample altitude was measured by GPS; groundwater level was measured with self-made electronic water level meter; shrub crown diameter was measured with steel tape; shade density of shrubs and coverage of herbaceous plants were measured by ocular estimate; groundwater samples in the study area were collected and analyzed in laboratory, their electrical conductivity and mineralization were measured by conductivity gauge; soil samples were collected at soil depths of 0-10 cm and 10-30 cm and analyzed in laboratory, and their conductivity was measured by conductivity gauge. Main indices included the richness index, important value index, average vegetation coverage in the plots, Shannon-wiener diversity index (H'), Simpson diversity index (D') and Sorensen similarity index. The results are as follows: (1) There were less herbaceous plants and their species in the Tarim Desert Highway shelterbelt; these herbaceous plants were composed of 13 species in 12 genera and 8 families. Most of the plants belonged to Chenopodiaceae and Compositae families, and many of them were perennial; (2) Some plant communities were consisted of the scarce species, but many ones are composed of single families; (3) Under different groundwater levels, the electrical conductivity of topsoil, distribution of herbs and species diversity were quite different; (4) The species diversity of herbaceous plants was closely correlated to groundwater level, groundwater electrical conductivity and topsoil electrical conductivity. The correlation coefficients between Shannon-Wiener index and groundwater level, groundwater electrical conductivity, electrical conductivity of soil at depth of 0-10 cm were 0.72, 0.63 and 0.69, and those between Simpson index and groundwater level, groundwater electrical conductivity, topsoil electrical conductivity were 0.65, 0.61 and 0.69, respectively. The coverage of herb community and the diversity index were increased with the raise of groundwater depth. Therefore, the study results can provide the basal information for conserving plant species diversity, improving the stability of the ecosystem, maintaining the unblocked desert highway traffic, and supplying the gap of herbaceous plant diversity in the shelterbelt along the desert highway. References | Related Articles | Metrics

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Osmolyte Accumulation of Armeniaca vulgaris under Continuous Drought Stress Kurban Halil, WANG Lei, Yakup Abduxukur, Anwar Salam 2011, 28 (1):  126-132.  Abstract ( 1742 )   PDF (503KB) ( 1111 )   In this paper, the osmotic regulation characteristics of 4 types of Armeniaca vulgaris seedlings under 80-day drought stress were studied. Drought stress treatment was applied to test the osmotic regulation characteristics of biennial seedlings of Armeniaca vulgaris f. aurantica L., Wang et D. F. Cui and Armeniaca vulgaris f. glyeyosma L., Wang et D. F. Cui, and the relative soil moisture content at depth of 15-20 cm, relative water content in leaves of A. vulgaris and the contents of Na+, K+, soluble protein, soluble sugar and proline were measured every 20 days. The results show that the relative soil moisture content at depth of 15-20 cm was decreased to slight drought stress (54%) after the seedlings were irrigated for 20 days, the relative water content in leaves was maintained higher than 80% except that in leaves of sweet kernel No.2. Under slight drought stress, K+ accumulation occurred in leaves of most wild apricots. Na+ accumulation occurred in leaves of all four types of wild apricot seedlings when the relative soil moisture content was decreased to the severe drought stress (47%-18%) after the seedlings were irrigated for 40-80 days. Soluble protein was relatively sensitive to drought stress, it was accumulated under slight to moderate drought stress, and such accumulation was possibly related to the drought-resistant capability of seedlings. Soluble sugar was also accumulated when drought stress was severer. Proline content was sharply increased under severe drought stress after the seedlings were irrigated for 60 days, but it was too low to contribute to osmotic regulation under hyperosmotic conditions, which suggests that the Proline accumulation is a symptom that the cells were injured under such drought stress. References | Related Articles | Metrics

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Comparative Study on Anatomical Structures of Plant Leaves of Stipagrostis Neas in Xinjiang HAN Cai-xia, ZHANG Hao, LI Bang, WANG Shao-ming 2011, 28 (1):  133-138.  Abstract ( 2261 )   PDF (514KB) ( 1364 )   There are only two species in Stipagrostis in Xinjiang, i.e. S. grandiglumiss and S. pennata. They can survive in deserts because of their adaptability to desert environment. In this study, the micro-morphological features of plant leaves of these two species were observed with an optical microscope, and their anatomical structures were compared. The results show that the structure of leaves of the two species is typical and adaptable to desert environment. The thickness of epidermis of their leaves is different, there is thorn hair over the upper epidermis of their leaves, and the outer wall of epidermis cells is thicker than the inner ones. The character of epidermis cell, type of stoma apparatus, shape and number of vascular bundle of midrib are all quite different. These differences of micro-morphological features might do some favors for studying the classification of Stipagrostis Nees. The type of stoma of S. pennata is hardly round or triangle and quite pristine, but S. grandiglumis is mostly round and evolutional. Moreover, S. pennata survives in north Xinjiang, while S. grandiglumis in south Xinjiang. The length and the shape of the tubercles are also distinctive because of the different species and environment. The tubercle of S. pennata is round, whereas S. grandiglumis is acuate. These traits are not only related to their different species but also consisted in their different entironment. References | Related Articles | Metrics

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Effect of Drought Stress on Physiological and Biochemical Properties of Amorpha fruticosa Seedlings YAN Shu-yun, ZHOU Zhi-yu, ZOU Li-na, QIN Yu 2011, 28 (1):  139-145.  Abstract ( 1893 )   PDF (510KB) ( 1775 )   In recent years, precipitation has reduced and groundwater has been seriously pumped. Drought trend has become as a global focus. Relevant research, such as the adaptive mechanism and drought resistance of plants to drought habitats, has become as one of the important issues of plant physiological ecology. Amorpha fruticosa is an easily-bred perennial deciduous legume shrub with its strong adaptability to drought stress. Objective of this study is to research the physiological, ecological and adaptive properties of A. fruticosa seedlings under drought stress so as to provide the theory and reference for its utilization and popularization in arid and semiarid areas. Effect of drought stress on physiological and biochemical properties of A. fruticosa were studied with potted seedlings. The changes of net photosynthesis rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), osmotic adjustment, protective enzymes, chlorophyll content, and water status were investigated. Results show that water saturation deficit (WSD), plasma membrane permeability and MDA content of A. fruticosa were increased with the increase of drought stress, while Pn, Tr and Gs were decreased. However, water use efficiency (WUE), SOD activity and contents of K, soluble sugar and free proline (Pro) were increased evidently. Soluble sugar and Pro played an important role in osmotic adjustment. Contents of chlorophyll a (Chla), chlorophyll b (Chlb), total chlorophyll (Chl) and carotenoid (Car) pigment were also increased with the decrease of soil moisture content. Moreover, the change of Chla/Chlb ratio was not so remarkable with the increase of drought stress intensity. A physiological injury of A. fruticosa occurred under the drought stress. Drought stress on physiological and biochemical properties of A. fruticosa seedlings was different to a certian extent. Generally speaking, the higher the drought stress intensity is, the more distinct the index change will be. Results in this study show that Tr, WUE, contents of Pro, soluble sugar and K as well as SOD and POD activity are the objective reflection of the adaptive mechanism of A. fruticosa seedlings to drought habitats and could be used as the identification indexes of its drought resistance. These results reveal that A. fruticosa seedlings increase their drought resistance by changing their physiological properties and have a certain resistance to drought stress. Adaptation of A. fruticosa seedlings could provide the theory and reference for its utilization and popularization in arid and semiarid areas. References | Related Articles | Metrics

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Change and Trend Prediction of Precipitation in the Central Hexi Corridor in Gansu Province in Recent 53 Years LIU Hong-lan, BAI Hu-zhi, ZHANG Jun-guo 2011, 28 (1):  146-150.  Abstract ( 1915 )   PDF (346KB) ( 1262 )   This paper analyzes mainly the decadal, annual, seasonal, monthly and spatial changes of precipitation in the central Hexi Corridor based on the recent 53-year precipitation data observed by 6 weather stations in the middle reaches of the Heihe River. The mean generating function was used to develop the prediction model of precipitation after analyzing the historical evolution of precipitation in the central Hexi Corridor. The results show that the annual precipitation was increased by 4.75 mm/10 a in recent 53 years, it was decreased during the period from the end-1980s to the early-1990s, but increased slowly from the late-1990s, which reveals that the climate in the central Hexi Corridor changed from the warming-drying trend to the warming-wetting trend. It was predicted that the annual precipitation will be in a slow increase trend in next 15 years. References | Related Articles | Metrics

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Spatiotemporal Evolution of Extreme Precipitation Events in Shaanxi Province during the Period 1961-2007 JIANG Chuang-ye, CAI Xin-ling, WU Su-liang, KANG Lan, HUI Ying 2011, 28 (1):  151-157.  Abstract ( 1819 )   PDF (535KB) ( 1076 )   In this paper, the spatiotemporal change of annual extreme precipitation events is analyzed using the daily precipitation data observed by 78 meteorological stations in Shaanxi Province during the period 1961-2009. The results show that the threshold of extreme intensity precipitation varied in a range of 18.7-9.5 mm/d, and it decreased northward. The extreme precipitation events in the province occurred mainly in rainy season from May to September, especially during the period from July to September, their duration was mostly for one day, the extreme precipitation events with 2-day duration occurred mainly in the central-southern part of south Shaanxi Province, and those with 3-day duration were occasional. The change trend of annual extreme precipitation events in the province was not significant in recent 49 years, but the extreme precipitation events increased in summer. The EOF results reveal that there were 2 main spatial distribution patterns of frequency of extreme precipitation events in the province. The first one (EOF1) was that the high or low frequency of extreme precipitation events was accordant in whole province, and there were 22-year and quasi-8-year periodic changes. The second one (EOF2) was that the frequency of extreme precipitation events in the southeastern part was opposite to that in the northwestern part, and there were the 12-14-year and 2-3-year periodic changes. References | Related Articles | Metrics

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Analysis on the Change of Sunshine Duration in Kashgar,Xinjiang in Recent 39 Years YANG Xia, CAI Mei, ZHAO Yi-zhou, ZHANG Yun-hui, LUO Ang, JIANG Yuan-an 2011, 28 (1):  158-162.  Abstract ( 2397 )   PDF (463KB) ( 1507 )   In this paper, the change of sunshine duration and its affecting factors are analyzed based on the data of sunshine duration and occurring days of blowing dust, floating dust and sandstorm in Kashgar, Xinjiang during the period 1970-2008. The results show that the sunshine duration was increased notably in recent 39 years. There were the significant seasonal and annual variations of sunshine duration. The sunshine duration was changed insignificantly in the 1970s, sharply decreased in the 1980s, slightly decreased in the 1990s, but sharply increased during the period of 2000-2008. There was a 28-year periodic change of sunshine duration in Kashgar, and also a 25-year one in recent 39 years. An abrupt change of sunshine duration occurred in 1997. The significant increase of annual, spring and summer sunshine durations was mainly caused by the obvious reduction of floating dust, however sandstorm and blowing dust were not the main factors affecting the sunshine duration in Kashgar. References | Related Articles | Metrics

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Observation of Ground Temperature at Shallow Layer of Different Dune Types in the Tazhong Area JIA Xiao-lu, YANG Qing, HUO Wen 2011, 28 (1):  163-167.  Abstract ( 2211 )   PDF (389KB) ( 1182 )   Land surface temperature affects the capability of long wave radiation, and it is an important parameter for studying climate change. The variation of air temperature and precipitation was often stressed in studying climate change in the Taklimakan Desert in the previous studies, but ground temperature in the desert was infrequently studied. In this paper, MicroLite 16K LITE5016 was used to examine the spatial distribution and temporal variation of ground temperature at shallow layer of different dune types in the Tazhong area located in the central Taklimakan Desert, where oceanic airstream is difficult to arrive. The Tazhong area is characterized by a typical continental climate with frequently and intensely wind-blown sand movement. The area of mobile dunes in Tazhong occupies more than 80% of the total area of the Taklimakan Desert. Temperature variation here is drastic, the maximum temperature is as high as 45.6 ℃, and the diurnal-nocturnal temperature difference is over 40 ℃. The annual sunshine duration in this area is 2 700 hours, accumulated temperature ≥0 ℃ is over 4 000 ℃, and the total solar radiation is 5 700-6 000 MJ/m2. Precipitation in this area is low, the annual precipitation is no more than 50 mm and only 4-5 mm in minimum, and it is extremely arid climate.The values of ground temperature at different depths (0 cm, 10 cm and 20 cm) over a mobile dune and an artificially-fixed dune in the Tazhong area were measured during the period from August 3rd to 10th, 2009. The results are as follows: (1) Daily range of ground surface temperature was high in summer both for mobile dune and artificially-fixed dune, it was decreased with the increase of depth, and it was the lowest at depth of 20 cm; furthermore, the maximum ground temperature occurred 2 hours later from noon, and the minimum one occurred at dawn; (2) The ground temperature of artificially-fixed dune was lower than that of mobile dune; (3) The difference between ground temperature and air temperature was the highest in summer; (4) Wind speed affected significantly the ground surface temperature regardless of mobile dune or artificially-fixed dune. References | Related Articles | Metrics

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Analysis on Relationship between Lake Change and Climate Change in the Ulan Buh Desert Ren Yu, GAO Yong, YU Yi, ZHANG Jing-bo, JIANG Jing-yu, XING Tie-peng 2011, 28 (1):  168-174.  Abstract ( 2137 )   PDF (598KB) ( 1566 )   In recent years, the lakes in desert have been significant changed. Based on the satellite data and climate data, this paper analyzes the variation of two lakes in the Ulan Buh Desert. Using CBERS CCD data during the period from 2000 to 2008, the best wave bands were chosen to process the image, such as the high-accuracy geometric registration and mosaic, the brim information was extracted, and the change figures of the lakes in the Ulan Buh Desert were charted. A spectral reflection curve was charted with a TM image in 2000 to identify the changed area of the lakes. In order to avoid the contingency, the areas of each lake in recent continuous years were used to calculate the average area of each lake. The correlation coefficients between lake areas and climate change in recent 20 years were calculated. The result shows that the trend was accordant well with the result of remote sensing detection, and there was a significant positive correlation between the lake area and the annual precipitation. The lakes with small area were more sensitive to climate change than those with large area. The study result shows that remote sensing is of high usability in monitoring the lakes in desert, especially in west Inner Mongolia. References | Related Articles | Metrics

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Research on Drought Disasters in Central Gansu Province during the Period from 1400 to 1999 CHENG Ai-fang, ZHAO Jing-bo 2011, 28 (1):  175-180.  Abstract ( 1857 )   PDF (445KB) ( 1283 )   In this paper, the historical documents of drought disasters in central Gansu Province during the period from 1400 to 1999 were collected and analyzed. The ranks, decadal change, seasonal change, regional variation and climatic background of drought disasters in central Gansu Province during this period were focused on. It was found that 280 times of drought disasters occurred in central Gansu Province during this period, approximately once every 2.14 years in average. Drought disasters were mainly the moderate ones and accounted for 45.4% of the total, followed by severe ones and accounted for 32.1% of the total, and the occurring frequency of tremendous and slight ones accounted for 10% and 12.5% of the total respectively. Occurrence of drought disasters in central Gansu during the period from 1400 to 1999 could be divided into three stages. The first stage was before the 1480s, and it was characterized by high occurring frequency and continuous increase of drought disasters; the second stage was between the 1490s and the 1700s, and it was characterized by low occurring frequency and continuous decrease of drought disasters; the third stage was after the 1710s, and it was characterized by high occurring frequency and fluctuated increase of drought disasters. Seasonally, drought disasters occurred mainly in summer, and followed by spring drought and successive two-or three-season drought. Spatially, severity of drought disasters was increased from southwest to northeast of central Gansu Province. Occurring frequency of drought disasters fluctuated sharply in central Gansu Province during the period from 15th century to 17th century due to climate fluctuation; occurring frequency of drought disasters was continuously increased with temperature decrease during the period from 18th century to 19th century. Occurring frequency of drought disasters was the highest during the warm period in the 20th century in recent 600 years. References | Related Articles | Metrics

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Flood Disasters and the Development of Early Warning Model for Railway LI Xiao-xia, WANG Yong, GUAN Xiang-ning, WANG You-sheng, QUAN Jian-rui 2011, 28 (1):  181-186.  Abstract ( 1515 )   PDF (453KB) ( 1110 )   Lanzhou Railway Bureau is a main personnel and material transportation artery in northwest China, and manages 5 main railways in the popedom of the bureau: the western section of the Longhai Railway, southern section of the Baotou-Lanzhou Railway, eastern section of Lanzhou-Xinjiang Railway, northern section of the Baozhong Railway and Gantangzi-Wuwei Railway and 10 branch lines. The railways in the popedom of the bureau pass through Gansu Province and Ningxia Hui Autonomous Region. In this area, weather and climate is diversity, rainfall is quite different from different regions, the geographical environment is complicated, there are the Gobi deserts, deserts, mountains, plateaus and other landforms, and flood disasters occur frequently along the railways. In this paper, the data of disrupted times and their durations of the railways as well as rainfall are used to discuss flood disasters along the railways within the popedom of Lanzhou Railway Bureau during the period from 2002 to 2007. The temporal variation of flood disasters along the railways and their relationship with precipitation are analyzed. Results show that the flood disasters along the railways varied with rainfall type and intensity for different railway sections. Flood disasters occurred mainly during the period from May to October, especially from July to August, and the proportions of disrupted times and their durations of the railways were 62% and 77% of the total flood disasters. The water-damaged railway sections were mainly distributed along 5 railways and increased from northwest to southeast, the regional feature of water-damaged railway sections was obvious, and flood disasters were the most serious along the railway sections from Lanzhou to Dingxi and then to Tianshui. In this 2 sections, the average annual disrupted times of the railways were 15 and 12, and the average annual disrupted durations of the railways were 40.8 and 20.8 hours, respectively. Flood disaster along the railways was closely related to precipitation. The correlation between the disrupted times of the railways and precipitation was 0.78, and the correlation between the disrupted duration of the railways and precipitation was 0.41. Regional heavy rainfall, severe convective weather and continuous rainfall were the main factors resulting in water damage of the railways. There were 85 flood disasters along the railways during the period from 2002 to 2007, in which 50.5% were caused by the severe convective weather, 42% by regional heavy rainfall, and 9.5% by autumn continuous rainfall. References | Related Articles | Metrics