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Effects of short-term low temperatures on photosystem II function of samara and leaf of Siberian maple (Acer ginnala) and subsequent recovery
XiangLiang PAN, DaoYong ZHANG, Xi CHEN, Li LI, GuiJin MU, LanHai LI, AnMing BAO, Jing LIU, HuaiSong ZHU, WenJuan SONG, JianYing YANG, JunYong AI
Journal of Arid Land    DOI: 10.3724/SP.J.1227.00057
Abstract (3627)      PDF(pc) (365KB)(2111)       Save
Samara is the reproductive organ (seed) for many tree species in arid land in northwestern China. It is ecologically important in population development due to its dispersal function. However, information on its photosynthesis and effect of environmental stresses on its photosynthesis is still very limited. In the present study, responses of photosystem II (PSII) activity in samara and leaf of Siberian maple to short-term chilling/freezing and subsequent recovery potential were comparatively investigated by using polyphasic fluorescence test. The samara had more efficient photosynthesis (Fv/Fm and PIABS) and more efficient electron transport (φEo) but lower energy dissipation (DIo/RC) than leaf. Generally, the PSII performance and the electron transport for both samara and leaf were inhibited under low temperature stress, accompanied by an increase of energy dissipation in PSII reaction centers (RCs). PSII of both samara and leaf was not markedly affected by chilling and could acclimate to chilling stress. Short-term freezing could completely inhibit PSII activity in both samara and leaf, indicated by the drop of values of Fv/Fm, PIABS, φEo to zero. PSII functional parameters of short-term dark frozen samara could be largely recovered whereas those of frozen leaf could not be recovered. The higher tolerance of samara to short-term low temperature stress than leaf is of great ecological significance for seed development, population establishment of Siberian maple.
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A preliminary molecular historical biogeography of Caragana (Leguminosae) based on ITS and trnL-F DNA sequence data
MingLi ZHANG, Yun KANG, JunBo YANG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.00064
Abstract (2787)      PDF(pc) (280KB)(2012)       Save
The nrDNA internal transcribed spacer (ITS) and cpDNA trnL-F internal spacer (IGS) sequence data of Caragana eight species and one outgroup Halimodendron halodendron, was employed to reconstruct a phylogenetic tree, then the area relationship was analyzed by means of component analysis (CA), Brooks parsimony analysis (BPA), and dispersal-vicariance analysis (DIVA), six areas were selected from two divided distributions of East Asia and Tethys in Caragana. The phylogenetic tree indicated that there were three distinctive groups, which were attributed to some morphological characters, first with pinnate foliage and deciduous rachis, second with palmate foliage and persistent sclerotic stick rachis, and third with pinnate foliage and persistent sclerotic stick rachis. The results of CA and BPA illustrated general area relationships. An explicit area relationship should be Altai-Sayan, Far East-NE China and North China (Hengduan Mountains). DIVA recognized several explanatory vicariance and dispersal events. As the scenario of Caragana distribution pattern, it looks like the vicariance versus dispersal plays more important role. In vicaraince, there are not only the isolated far-distance vicariance, but also the adjacent vicariance especially a vicariance between Hengduan Mountains and North China.
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Research progress and developing trends on microorganisms of Xinjiang specific environments
HuiXia PAN, ZhengMing CHENG, YuanMing ZHANG, ShuYong MU, XiaoLing QI
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00051
Abstract (2838)      PDF(pc) (79KB)(2098)       Save
Microorganisms and its metabolic types are diverse in Xinjiang because of those extreme/special environments of drought, high or low temperature, saline and alkaline, oligotrophy. This article reviewed the research progress and achievements of various microbial resources (bacteria, fungi and actinomycete) in the special environments from the point of its ecology, development and application. Meanwhile, the development trend, protection and sustainable utilization of the microorganism resources were discussed.
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Local convergence zones or discontinuous lines in the Taklimakan Desert, Northwest China
Masatoshi YOSHINO, Takashi ISHIYAMA, Jun SUZUKI
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00077
Abstract (3045)      PDF(pc) (1730KB)(2266)       Save
In order to study convergence zones or discontinuous lines formed locally in the Taklimakan Desert, we analyzed available MODIS images onboad TERRA or AQUA satellite for ten cases: 29 March 2002, 14 April 2002; 2 January 2003; 21 April 2003; 26 March 2004; 28 April 2004; 30 January 2005; 25 June 2005; 3 December 2005; and 26 July 2006. We used weather maps published by the Japan Meteorological Agency for the Asia and Pacific region at 500 hPa, 700 hPa and 850 hPa, at 00Z and 12Z to analyze the meteorological conditions occurring in each case. We estimated the positions of air streams, convergence zones or discontinuous lines between them, and thermal conditions on the maps and confirmed the presence of cumulus and cumulonimbus clouds through satellite images in particular. After a review of previous studies, this paper introduced the results of the present study. Closed warm areas in the Taklimakan Desert and on the Tibetan Plateau and local convergence zones or discontinuous lines in the Taklimakan Desert were discussed together with their diurnal changes, using composite maps of the ten cases. Along the long axis of the desert the convergence zones or discontinuous lines normally extend 70–80 km in a west-east direction, but are suspected to exceed 100 km in extreme cases. On the other hand, the convergence zones or discontinuous lines extending in a north-south direction on the southern fringe of the desert have a length of 40–60 km. The closed warm areas show clear diurnal changes, but they were not detected at the 500 hPa level. An example of a clear convergence zone running in a north-south direction on 26 July 2006 was presented in detail with corresponding satellite images.
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Characteristics of the soil microbial population in forest land irrigated with saline water in the desert area
ZhengZhong JIN, JiaQiang LEI, XinWen XU, ShengYu LI, JingLong FAN, SiFeng ZHAO
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00107
Abstract (3214)      PDF(pc) (355KB)(3467)       Save
The study of soil microbial populations and diversity is an important way to understanding the soil energy process. In this study we analyzed the characteristics of soil microbial populations of the Tarim Desert Highway shelter-forest, by identifying microbial fatty acids and using methods of conventional cultivation. The results illustrated that the amount of soil microbial activity and the diversity of soil microbial fatty acid increased significantly with the plantation age of the shelter-forest; the soil microbial population was dominated by bacteria. The fatty acids of C14:0, C15:0, C16:0, C17:0, C18:1ω9, C18:0, C18:2ω6 and C21:0 were found to be dominant soil microbial fatty acids in the shelter-forest soil. Principal analysis and regression analysis showed that (1) concentrations of fatty acids of C14:0, C16:0 and C18:0 could be used as indicators of total soil microbial population; (2) soil bacteria and actinomycetes populations were closely correlated with the amount of fatty acids of C15:0 and C17:0; and (3) soil fungi were closely correlated with the amount of fatty acids of C18:1ω9 and C18:2ω6.
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Cited: Baidu(3)
Changes in stress within grassland ecosystems in the three counties of the source regions of the Yangtze and Yellow Rivers
YiPing FANG, DaHe QIN, YongJian DING
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00116
Abstract (3191)      PDF(pc) (288KB)(2881)       Save
Based on a database of more than 40 years of second production process and energy flow records for Maduo, Qumalai and Yushu counties, a dynamic model of the stress within grassland ecosystems was established using a nonlinear regression method for this source regions of the Yangtze and Yellow Rivers. The results show that dynamic curves of stress within grassland ecosystems in the three counties were in the shape of an inverted “U” during the period 1965–2007. It also revealed that the variation in actual amount of livestock inventories reflected the general trends of the stress within the grassland ecosystems in the source regions, although there were many other factors for the increase or reduction in grassland ecosystem stress.
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Effect of crude oil pollution on organic carbon and humus content in grey-brown soils in Mangyshlak, Pre-Caspian Sea Region
Saimbulek Dosbergenov
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00133
Abstract (3008)      PDF(pc) (121KB)(3860)       Save
The organic carbon and humus content in oil polluted brown and grey-brown soils in Mangyshlak, Pre-Caspian Sea Region, was analyzed from 2000 to 2008. The results indicated that bitumen substances from crude oil pollution deteriorated the soil property, however, the organic carbon content increased significantly. The products of oil pollution changed the composition of carbonaceous substances which formed soil humus, and changed the ratios of the humus components. Residual insoluble carbon increased with the rise of oil organic carbon. The mobility of humus components was significantly increased because of the high oxidation-reduction process in the topsoil, and the humus content and microorganism activity increased. The organic carbon content increased significantly, while it decreased with the distance away from the oil well. The rearrangement of physical, physical-chemical and chemical properties of the polluted soils was significant.
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Saline dust storms and their ecological impacts in arid regions
Jilili Abuduwaili, DongWei LIU, GuangYang WU
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00144
Abstract (4455)      PDF(pc) (210KB)(5009)       Save
In many arid and semiarid regions, saline playas represent a significant source of unconsolidated sediments available for aeolian transport, and severe saline dust storms occur frequently due to human disturbance. In this study, saline dust storms are reviewed systematically from the aspects of concept, general characteristics, conditions of occurrence, distribution and ecological impact. Our researches showed that saline dust storms are a kind of chemical dust storm originating in dry lake beds in arid and semiarid regions; large areas of unconsolidated saline playa sediments and frequent strong winds are the basic factors to saline dust storm occurrence; there are differentiation characteristics in deposition flux and chemical composition with wind-blown distance during saline dust storm diffusion; and saline dust storm diffusion to some extent increases glacier melt and results in soil salinization in arid regions. An understanding of saline dust storms is important to guide disaster prevention and ecological rehabilitation.
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Processes and trends of the land use change in Aksu watershed in the central Asia from 1960 to 2008
DeCheng ZHOU, GePing LUO, Lei LU
Journal of Arid Land    2010, 2 (3): 157-166.   DOI: 10.3724/SP.J.1227.2010.00157
Abstract (2793)      PDF(pc) (374KB)(3279)       Save
Land use change (LUC) in trans-boundary watersheds is of great importance to environmental assessment. The Aksu River is the largest trans-boundary river crossing Kyrgyzstan and China, but there was little information on the LUC of the watershed. We quantitatively investigated the processes and trends of its LUC by using analytic models based on the land use data derived from the remote sensing images and topographic maps. The LUC was in the quasi-balanced status with a slight difference between the loss and the gain of the area for most land use types during the period of 1960-1990, whereas transferred to the unbalanced status with significant difference between the loss and gain of the area during the period of 1990-2008. At the same time, land conversion direction changed from two-way transition to one-way transition for the most land use types. The integrated rate of net change of land use during the period of 1990-2008 is 2.1 times of that during the period of 1960-1990. Information on the processes and trends of LUC is valuable for better understanding the environmental changes across the whole trans-boundary watershed, and helpful to decision-making management for Kyrgyzstan and China.
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Tectonic geomorphological characteristics for evolution of the Manas Lake
YongHui YAO, HuiGuo LI
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00167
Abstract (3141)      PDF(pc) (514KB)(5331)       Save
Owing to global climatic changes and human activities, the lakes have changed dramatically in the Junggar Basin of Xinjiang in recent 50 years. Based on the remote sensing images from Beijing Satellite No.1 in 2006 together with the measured topographical data in 1999 and other data since the 1950s, this paper analyzes mainly the features of landforms around the Manas Lake and the changes of feeding sources of the lake. The results are as follows: (1) Tectonic movement brought about the fundamental geomorphological basis for lacustrine evolution, and the Manas Lake is one of small lakes broken up from the Old Manas Lake due to tectonic movement and drought climate; the Manas Lake had existed before the Manas River flowed into it in 1915. The geomorphologic evidences for evolution of the Manas Lake include: (a) Diluvial fans and old channels at the north of the lake indicate that the rivers originating from the north mountains of the Junggar Basin had fed the Old Manas Lake and now still feed the lake as seasonal rivers; (b) The Old Manas Lake was fed by many rivers originating from the mountains, except for the Manas River, from the evidence of small lakes around the Manas Lake, old channels, alluvial fans, etc.; (c) The elevations of the alluvial and diluvial fans are near to the 280 m a.s.l. and all of the small lakes and lacustrine plains are within the range of the 280 m a.s.l., which may prove that the elevation of the Old Manas Lake was about 280 m a.s.l.; (d) Core analysis of the Manas Lake area also indicates that the Manas Lake has existed since Late Pleistocene epoch. (2) Analysis on the feeding relations between the lakes and the lacustrine evolution shows that human activities are one of main driving forces of the lacustrine evolution in recent 50 years, and it is the precondition of restoring and maintaining the lacutrine wetlands in the study area to satisfy the feeding of the Baiyang and Manas rivers to the Manas Lake.
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Variation in soil water content to rainfall under Caragana microphylla shrub in Horqin Sandy Land
ShaoKun WANG, XueYong ZHAO, Hao QU, YaYong LUO, JianYing YUN
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00174
Abstract (2936)      PDF(pc) (204KB)(3026)       Save
In order to investigate the spatio-temporal variability of soil water content to rainfall under Caragana microphylla shrub in Horqin Sandy Land, a plot of 25 m × 25 m, where there were 6 shrub canopies of C. microphylla, was sited for measuring soil water content at two soil layers of 0-20 cm (top layer) and 20-40 cm (lower layer). Soil water content was measured on the 1st, 5th, 10th and 15th day after a 42 mm rainfall in Naiman of Inner Mongolia. The results showed that soil water contents at both layers under C. microphylla shrub were gradually decreased after the rain. Soil water content at the top layer outside the shrub canopy was higher than that inside the shrub canopy within 5 days, and became similar inside and outside the shrub canopy on the 10th day after the 42 mm rainfall, and it was lower outside than that inside the shrub canopy on the 15th day. The soil water content at lower layer in the area without shrubs was higher than that under shrub canopy all along. All the measured values of soil water content can be fitted to a variogram model. There was significant autocorrelation of the values of soil water content between top layer and lower layer, except for the fourth measured values of soil water content at top layer. The range and spatial dependence of soil water content at top layer were lower than that at lower layer.
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Species composition, distribution patterns and ecological functions of biological soil crusts in the Gurbantunggut Desert
YuanMing ZHANG, Nan WU, BingChang ZHANG, Jing ZHANG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00180
Abstract (3804)      PDF(pc) (301KB)(4114)       Save
As one of the most important biological factors that maintain the stability of the largest fixed and semi-fixed desert in China, the Gurbantunggut Desert, the biological soil crusts (BSCs) develop well and play critical ecological roles in the desert ecosystem. In this paper, we briefly summarize our research findings since 2002 including species composition, distribution pattern and ecological functions of BSCs in the desert. Our results indicate abundant species diversity of BSCs in the Gurbantunggut Desert in comparison to other deserts in China. At the scales of sand dune or whole desert, the distribution patterns of BSCs are location-specific. The existence of BSCs in this desert could: (1) accelerate the formation of desert soil and the weathering of minerals; (2) accumulate organic matter in surface soil through related species in soil crusts; (3) enhance the abilities of sand surface to resist wind erosion; (4) influence seed germination of vascular plants; and (5) enhance the production of dew deposition on sandy soil surface.
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Effects of sodium on nitrate uptake and osmotic adjustment of Suaeda physophora
JunFeng YUAN, ChangYan TIAN, Gu FENG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00190
Abstract (2659)      PDF(pc) (323KB)(2793)       Save
Na+ ions play an important role in the growth of halophyte. The effect of Na+ ions on nitrate uptake and osmotic adjustment in the euhalophyte Suaeda physophora was investigated under glasshouse conditions. Seedlings were exposed to 1 mmol/L NaCl (control), 300 mmol/L NaCl, 150 mmol/L NaCl plus 150 mmol/L KCl or 300 mmol/L KCl treatments for 24 d. Dry weight was not affected greatly by different salt treatments, but water content and succulence in leaves of S. physophora were significantly increased at 300 mmol/L NaCl and 150 mmol/L NaCl plus 150 mmol/L KCl treatments. The concentrations of Na+ and NO3- in leaves of S. physophora were the highest at 150 mmol/L NaCl plus 150 mmol/L KCl, but lowest at 300 mmol/L KCl treatment. Moreover, the increase of NO3- concentration did not result in the decrease of Cl- concentration at 150 mmol/L NaCl plus 150 mmol/L KCl treatments. The estimated contribution of NO3- to osmotic potential (CNO3) in leaves of S. physophora was 9.8% at 150 mmol/L NaCl plus 150 mmol/L KCl, and CNa and CCl were 31.0% and 23.3%, respectively. However, CNO3, CNa and CCl were respectively 1.6%, 7.9% and 11.9% at 300 mmol/L KCl treatment. It is concluded that Na+ stimulates NO3- absorption and the stimulation is independent on the internal or the external Cl- concentration in the euhalophyte S. physophora. These characteristics may explain the high levels of N in leaves of saline desert plants in arid ecosystem.
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Spatial integration of oasis city group around the western margins of the Tarim Basin
Yu YANG, XiaoLei ZHANG, Jun LEI, Wen DONG, WeiYao ZENG, Chao GAO
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00214
Abstract (3021)      PDF(pc) (365KB)(2948)       Save
In this paper, the oasis cities in Kashgar Prefecture and Kizilsu Kirgiz Autonomous Prefecture are taken as an example, through the factor analysis, spatial attraction interaction model and location quotient methods, urban hierarchy system, the intensity of urban economic ties, economic subordination degree, and structure of city functions were analyzed. The results indicated: (1) The urban hierarchy system takes Kashgar city as the main center, Artux city, Yarkant county and Maralbexi county as the sub-centers; (2) The intensity of economic ties among Kashgar city and each county is much higher than others. The interaction of Kashgar city, Shufu county and Shule county are the strongest, and the economic ties of Yarkant, Kagilik, Poskam counties are relatively close; All cities in the study area are economically subordinate to Kashgar city. (3) Three cities of Kashgar city, Shufu county and Shule county should connect strongly, with Kashgar city as the core. The cities and towns along the Southern Xinjiang Railway and along National Road 315 should be regarded as two strips, and the two city strips along the border, and the city strip along Provincial Road 215 should be treated as three axes. The ring structure strategy of “core ring, closer ring and radiated ring” was proposed. (4) It was proposed to build Kashgar city group in the north, and Yarkant city group in the south, Maralbexi city group in the southeast, and Taxkorgan border city group with four inner groups’ development strategy.
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Rare and endangered plant species of the Chinese Altai Mountains
Marina V. OLONOVA, DaoYuan ZHANG, ShiMing DUAN, LinKe YIN, BoRong PAN
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00222
Abstract (4684)      PDF(pc) (442KB)(5562)       Save
Altai (also named Altay in China) Mountain Country (Mountain System) is a unique natural region, located on the border between different floristic regimes of the Boreal and ancient Mediterranean sub-kingdoms, where distribution of plant species is actually limited. It is known to have sufficient endemic floral biodiversity in the Northern Asia. Many plants of Altai Mountain System need effective care and proper conservation measures for their survival and longer-term protection. Important Plant Area identified as the IUCN (the International Union for Conservation of Nature), specified criteria attract global attention for protection of floral biodiversity across the world. The records of 71 plant species from the Chinese Altai Mountains attributed to the criterion A and the dark conifer forests of Chinese Altai Mountains satisfied the criterion C, which may help qualify to fulfill the national obligation of the Convention on Biological Diversity.
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Revision of two species of Calligonum from the desert of Xinjiang, Northwestern China
Ying FENG, BoRong PAN, GuanMian SHEN
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00231
Abstract (3379)      PDF(pc) (145KB)(2644)       Save
By examination of Calligonum pumilum A. Los. and Calligonum ruoqiangense Liou f., collected from natural habitats, and the analysis of their variance, this paper revealed that the morphological characters of these specimens are quite different from each other, especially in the twist direction of ribs on fruits, rows of bristles along each rib, rigidity, interweaving degree of bristles, and their geographical distribution. Therefore, it is suggested that C. pumilum and C. ruoqiangense should be considered as two independent species.
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Characteristics and dynamics analysis of Populus euphratica populations in the middle reaches of Tarim River
JunXia WU, XiMing ZHANG, ChaoZhou DENG, GuoJun LIU, Hong LI
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00250
Abstract (3236)      PDF(pc) (324KB)(2549)       Save
Populus euphratica Oliv. is widely distributed along the Tarim River. Maintaining stability of P. euphratica population is important to local development. This study explored the static life table, survivorship curves and four function curves (survival rate, cumulative mortality rate, mortality density, and hazard rate), and development index of P. euphratica population in the middle reaches of Tarim River. The results indicated that the age structure of P. euphratica population belonged to positive pyramidal type, which meant young age-class individuals occupied most populations. The number ofⅠ-Ⅱage classes accounted for 66.2% of whole population, and this indicated that there were abundant subsequent seedlings resources to support the growth of P. euphratica population in the middle reaches of Tarim River. The survivorship curve of P. euphratica belonged to the Deevey Ⅲ (concave-type) and the development index was 47.72%. Four function curves revealed that the individuals of P. euphratica sharply decreased at the initial stage and then leveled off at the late stage of survival curve. Time sequence prediction models predicted that the number of midlife individuals would increase in future 10, 20, 30 years, and P. euphratica population grew steadily as a result of rich saplings.
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Robinia pseudoacacia leaves improve soil physical and chemical properties
Babar KHAN, Abdukadir Ablimit, Rashed MAHMOOD, Muhammad QASIM
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00266
Abstract (2916)      PDF(pc) (306KB)(2866)       Save
The role of the leaves of Robinia pseudoacacia L., which is widely distributed in the arid lands, on improving soil physical and chemical properties was analyzed at various incubation periods. The incubated soils added with 0, 25, 50 and 75 g Robinia pseudoacacia leaves were tested after consecutive incubation intervals of 6, 8 and 10 months and the different soil parameters were measured. The results showed the increases in organic matter (OM), extractable K, cation exchange capacity (CEC), aggregate stability and water holding capacity, but the decreases in pH value and bulk density after 6 months' incubation. The gradual decrease in change rates of soil properties indicated less microbial population and organic residual mineralization under acidic conditions, which were resulted from fast decomposition of leaves after the first 6 months incubation. The increases in soil organic matter content, extractable K, CEC, aggregate stability and water holding capacity and the decreases in soil pH and bulk density provide favorable conditions for crop’s growth.
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Dynamic changes of a typical linear dune in the Tengger Desert
KeCun ZHANG, KenJi KAI, JianJun QU, YuQuan LING, QingHe NIU
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00272
Abstract (3202)      PDF(pc) (622KB)(2942)       Save
The dynamical processes of a typical linear dune including morphological features, dune ridge swing range and crest height were investigated at different monitoring periods in the hinterland of Tengger Desert. The results indicated that the development of linear dune depends on not only the northwesterly prevailing wind, but also the winds from northeast and southwest. The dune ridge swayed along its fundamental strike and took on an eastward movement gradually. The original dune strike was NW70° on August 3, 1994, and then changed to NE15° on April 21, 2001. The dune crest increased by 1.8 m longitudinally, which manifested strong wind-blown sand activities in this region. Wind erosion frequently occured at the bottom of sand dune, while sand accumulation appeared on its mid-upper section. The mean wind erosion depth was 25 cm on the bottom of linear dune and the height difference of the control points on the dune’s ridge was 1.13 m. Although the linear dune swayed laterally, the horizontal displacement of its ridge moved eastward 5.8 m averagely. The swing range of the dune crest line is very distinct, with a maximum value of 13.2 m. The highest site on the K-profile swayed on both sides of the dune ridge and the heights were 19.88 m at the control point K5, 19.61 m at K6 and 19.05 m at K7, respectively. The results indicated that the lateral swing of the linear dune was distinct under the northwesterly wind and it moved toward east gradually.
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Cited: Baidu(3)
Reconstructing the annual precipitation variation since 1899 based on tree-ring width in the western Hedong sandy land of Ningxia
YaJun WANG, ShangYu GAO, YuZhen MA, RuiJie LU, YanLi SANG, HongWei MENG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00286
Abstract (2915)      PDF(pc) (366KB)(2622)       Save
Based on the analysis of the correlation between the tree-ring width of Pinus tabulaeformis and the climate factors in the western Hedong sandy land of Ningxia, a conversion equation between the annual precipitation and the tree-ring width since 1899 was reconstructed. The results of cross verification indicated that the conversion equation is stable and the reconstructed results are reliable. The result of reconstructed annual precipitation showed the remarkable fluctuation of precipitation and dry-to-wet variation before the 1940s. The smaller fluctuation and high frequent changes of precipitation occurred during the period of 1940s-1980s and after the 1980s the change trend of the precipitation became high periodic extent and low frequent. The study found that there were some coincidences with the climate change in Changling Mountains, Helan Mountains and the east of Qilian Mountains. The relatively dry periods in the beginning of 20th century, 1920s to 1930s, the end of the 20th century and 2004 to 2006 in the western Hedong sandy land of Ningxia accelerated the desertification, while the relatively humid period during the periods of the 1910s-1920s, 1930s-1940s and 1990s is favorable to prevent and control the desertification, and to weaken the climate warming and drying. The periods of annual precipitation variation in the western Hedong sandy land of Ningxia since 1899 are approximately 2-4 years, 5-7 years and 10 years.
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Cited: Baidu(14)
The changes of Lop Nur Lake and the disappearance of Loulan
ZhiChao WANG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00295
Abstract (3531)      PDF(pc) (332KB)(3559)       Save
The causes of the disappearance of the ancient town of Loulan in Xinjiang, China have been generally agreed to derive from two factors: human activities and natural factors (environmental variations). In this paper, the Muzart Glacier was selected as an example, and found that the length of the glacier has been gradually decreasing and the snow line has been retreating to a higher altitude, both results contributing to a decrease in river flow below the Muzart Glacier. From the distribution of moraines in the Tianshan Mountains and adjacent areas in different periods, the paper speculates that there have been four minor glacial periods since the Quaternary. Although the durations and scales of the four minor glacial periods were different, they all indirectly influenced the formation and disappearance of the Lop Nur Lake. The events of the fourth minor glacial period are the important impact factors in the existence and disappearance of Loulan. Whether the disappearance of Loulan can be related to the events of the three previous minor glacial periods needs further investigation.
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The climatic and hydrological changes and environmental responses recorded in lake sediments of Xinjiang, China
Long MA, JingLu WU, Jilili Abuduwaili
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00001
Abstract (3201)      PDF(pc) (412KB)(3612)       Save
Based on the analyses of environmental proxy data in lake sediments and instrumental records of Xinjiang in northwest China, the Holocene climate and hydrological variability and its environmental responses were studied in different time scales and regions. The results showed that the Holocene climate variability had obvious differences between the north and south of Xinjiang. In northern Xinjiang, the Holocene climate was dry in the early period, humid in the middle period, and then changed to dry in the late period. However, the climate transition times were not consistent in different regions. In southern Xinjiang, although there were many different types of climate change patterns inferred from different catchments, the warm and wet climate was recorded in most lake sediments in the middle Holocene. According to comparisons of some millennium scale records in lake sediments, the climate was warm and dry in the past 100 years. It can be concluded the climate showed a trend of aridity in Holocene. Especially in recent 50 years, the lake area has been shrinking rapidly because of the population growth and social economic development, which brings some environmental problems. Lake level and area changes were sensitively affected by the climate variation in geological history of Xinjiang and the lake level will continue to shrink because of the drought climate and strengthened human activities.
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Impact factors of soil wind erosion in the center of Taklimakan Desert
Qing HE, XingHua YANG, Ali Mamtimin, ShiHao TANG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00009
Abstract (4344)      PDF(pc) (239KB)(7645)       Save
The development and progress of soil wind erosion are influenced by the factors of climate, terrain, soil and vegetation, etc. This paper, taking Tazhong region, a town in the centre of the Taklimakan Desert, as an example and using comparative and quantitative methods, discussed the effects of climate, surface roughness (including vegetation cover) and surface soil properties on soil wind erosion. The results showed that the climate factor index C of annual wind erosion is 28.3, while the maximum of C is 13.9 in summer and it is only 0.7 in winter. The value of C has a very good exponential relationship with the wind speed. In Tazhong region, the surface roughness height is relatively small with a mean of 6.32 × 10-5 m, which is in favor of soil wind erosion. The wind erosion is further enhanced by its sandy soil types, soil particle size, lacking of vegetation and low soil moisture content. The present situation of soil wind erosion is the result of concurrent effects of climate, vegetation and surface soil properties.
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Phenotypic plasticity in response to soil moisture availability in the clonal plant Eremosparton songoricum (Litv.) Vass.
JianCheng WANG, Xiang SHI, DaoYuan ZHANG, LinKe YIN
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00034
Abstract (2823)      PDF(pc) (189KB)(3974)       Save
Eremosparton songoricum (Litv.) Vass is a dwarf clonal shrubby legume developed on the windward slopes of mobile or semi-fixed sand dunes of Central Asia. It is assumed that E. songoricum must possess a high degree of phenotypic plasticity for such a heterogeneous habitat. The variations of E. songoricum plants growing in two typical microhabitats (the upper slope and the lower slope of semi-mobile dune) were investigated. The morphological characteristics and the biomass allocation patterns were measured and compared at the clonal fragment level. Compared with the clonal fragment on the lower slope of dune, the clonal fragment on the upper slope of the dune (a) declined in total biomass and ramet height, (b) increased the length of rhizomes and the number of roots, (c) increased the degree of asymmetry, and (d) heightened allocation to the belowground biomass. Our results confirmed the hypothesis of high phenotypic adjustment capacity of E. songoricum to habitat moisture availability. Phenotypic plasticity of E. songoricum contributed to reduce the damage risk, led to an environmentally induced specialization in function of resources exploitation, resulted in its persistence in heterogeneous environments and was adaptive in sand dune environment.
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Recommending the IHACRES model for water resources assessment and resolving water conflicts in Africa
Samir Mohammad Ali Alredaisy
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00040
Abstract (3563)      PDF(pc) (220KB)(4411)       Save
The International Association of Hydrological Sciences (IAHS) recognized the lack of hydrological data as a world-wide problem in 2002 and adopted the Prediction of Ungauged Basins (PUB) as a decadal research agenda during the period of 2003 to 2012. One of the objectives is to further develop methodologies for prediction in ungauged basins and to reduce uncertainties in model prediction. Estimation of stream flows is required for flood control, water quality control, valley habitat assessment and water budget of a country. However, the majority of water catchments, streams and valleys are ungauged in most developing countries. The main objective of this paper is to introduce the IHACRES (Identification of Hydrographs and Components from Rainfall, Evaporation and Stream) model into African hydrological planning as a methodology for water resources assessment, which in turn can be used to resolve water conflicts between communities and countries and to study the climate change issues. This is because the IHACRES model is applied for the estimation of flows in ungauged catchments whose physical catchments descriptors (PCDs) can be determined by driving variables (i.e. rainfall and temperature); and also in gauged streams but whose gauging stations are no longer operational but historical data are available for model calibration. The model provides a valuable insight into the hydrologic behaviour of the upper water sources for valleys as well as provides a useful methodology for water resources assessment in situations of scarce financial resources in developing countries. In addition, it requires relatively few parameters in its calibration and has been successful applied in previous regionalization studies. It will also make possible the equitable distribution of water resources in international basins and rivers’ catchments. This paper does not apply the model anywhere, but recommends it as a methodology for water resources assessment in order to cure water conflicts on the African continent.
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Status and distribution of ungulates in Xinjiang, China
XingYi GAO, WenXuan XU, WeiKang YANG, David A BLANK, JianFang QIAO, KeFen XU
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00049
Abstract (3638)      PDF(pc) (205KB)(4812)       Save
Based on a long-term field investigation and other research results, we reviewed the status and distribution of ungulates in Xinjiang, China. The ungulates in Xinjiang included 19 ungulate species (30 subspecies) from 6 families and 2 orders. Among them, 3 species (2 subspecies) relate to Equidae (Perrisodactyla), and 16 species (28 subspecies) are from 5 families of Artiodactyla. In this paper, we analyzed the conservation status of most rare and important 13 ungulate species. Firstly, we proposed the protection of genetic diversity of Camelus ferus and the distribution areas of Moschus sifanicus, Procapra przewalskii and Saiga tatarica in Xinjiang. We found that Moschus sifanicus but not Procapra przewalskii distributed in Xinjiang. It was not clear whether the remnant populations of Saiga tatarica existed in Xinjiang and China-Kazakhstan border or not. We discussed that the protection level and rational use of Capra sibirica and enhancing protection level and enlarging monitoring and research projects for Pantholops hodgsoni and Gazella subgutturosa. And we would like to suggest Forestry Department to develop the captive breeding of Tibetan antelope for rational use. In addition, the captive breeding of Cervus elaphus in Xinjiang was reviewed. Local government should lessen strong control to Cervus elaphus because of many breeding centers’ establishment.
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Biofilter: a promising tool for mitigating methane emission from manure storage
Qiang HUANG, Qiang ZHANG, Nazim CICEK, Danny MANN
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00061
Abstract (3126)      PDF(pc) (177KB)(5783)       Save
Liquid manure storage may contribute to methane (CH4) emission and this emission can be greatly reduced if appropriate management practices are applied. Biofiltration has been used in other fields for mitigating greenhouse gas (GHG) emission (e.g., landfill) and shown promise for mitigation CH4 emission from liquid manure storage. It has been reported that biofilter was capable of reducing 80% of CH4 emissions from manure storage. The CH4 removal efficiency is influenced by many factors, including CH4 and O2 concentrations, temperature, moisture, composition of the filter bed, nutrient, and empty bed residency time (EBRT). Biological conversion of methane of a biofilter is a slow process due to the low water solubility of methane. The residence times (EBRT) between 5 min and 5 h have been used, whereas a typical EBRT of 25 s is used for common biofilter applications. Temperature at which methanotrophic bacteria are active ranges from 10oC to 45oC. The maximum activity is found at around 30oC. The optimal filter bed water content depends on both the gas flow rate and the type of filter bed (soil, compost, etc.) and ranges from 30%–70% of the water holding capacity. Compost is the best material for filter bed. The optimal pH for methanotrophic bacteria is neutral to slightly acidic. Copper and nitrogen compounds especially nitrate are important nutrients to methanotrophic bacteria but their optimal concentrations have not been founded. Phosphorus and other elements such as potassium and manganese are reported to affect the performance of methanotrophic bacteria but need further confirmation.
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Cited: Baidu(12)
Limitations on the recruitment of the rare sand shrubby legume Eremosparton songoricum (Fabaceae) in Gurbantunggut Desert, China
DaoYuan ZHANG, HuiLiang LIU, Xiang SHI, JianCheng WANG, YongKuan ZHANG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00075
Abstract (2817)      PDF(pc) (313KB)(3037)       Save
Eremosparton songoricum, a rare and endemic sand dune plant, appears to be experiencing recruitment failure. The structure of five populations from the Gurbantunggut Desert, China, was investigated for recruitment patterns, and two of them were examined for flowering, pollination and seed germination limits on regeneration. The results showed that total 150 seedlings only occurred on line transects in riverside Dure population, but they all died half a month later; no seedlings occurred in other four hinterland desert populations indicating recruitment was a failure at all populations although flowers were plentiful. Reproductive success depends on pollinators. Nectar is ‘reward’ for pollinators, with 0.06 μL–0.12 μL and 0.15 μL–0.35 μL per flower in Dure and Kabu populations, respectively, in continuously two secreting days. Spontaneous self pollination is rare with nearly zero fruit production. Geitonogamous self pollination is predominant with 14.47% fruit set. Seed mass in the riverside Dure population was significantly greater than that in other hinterland desert populations. Consequently, the Dure population exhibited a significantly higher germination rate (about 90%) than those in other populations (about 30%). Results suggested that recruitment failure of E. songoricum is not due to flower shortage, pollination limitation, or poor seed germination but environmental pressure and/or human disturbance.
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Spatial distribution of vegetation and the influencing factors in Qaidam Basin based on NDVI
WenBin ZHU, AiFeng LV, ShaoFeng JIA
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00085
Abstract (6306)      PDF(pc) (377KB)(6942)       Save
The spatial distribution of vegetation in Qaidam Basin was analyzed using GIMMS (Global Inventory Modeling and Mapping Studies) / NDVI (Normalized Difference Vegetation Index) data set from January 1982 to December 2006. Based on the data of precipitation, terrain, stream systems, land use and the map of vegetation distribution in Qaidam Basin, we studied the factors influencing the spatial distribution of vegetation. The results showed that the vegetation was generally low in Qaidam Basin and there was a clear semi-ring structure from southeast to northwest. In some areas, the existence of rivers, lakes and spring belts turned this semi-ring structure into a non-continuous state and formed distinct bright spots and continuous linear features. There were four main factors that affected the spatial distribution of vegetation coverage in Qaidam Basin, i.e., precipitation, hydrological conditions, altitude and human activities. Precipitation and altitude have a correlation and determine the basic pattern of vegetation distribution in Qaidam Basin. The impacts of hydrological conditions and human activities were mainly embodied in partial areas, and often broke the pattern of vegetation distribution dominated by precipitation and altitude.
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A cladistic scenario of Southern Pacific biogeographical history based on Nothofagus dispersal and vicariance analysis
MingLi ZHANG
Journal of Arid Land    2011, 3 (2): 104-113.   DOI: 10.3724/SP.J.1227.2011.00104
Abstract (2977)      PDF(pc) (253KB)(2914)       Save
Nothofagus is regarded as a key group for interpreting Southern Pacific biogeographical history. Based on a molecular phylogenetic tree, a quantitative dispersal-vicariance analysis (DIVA) of the genus is presented. The results indicate that the ancestral area of Nothofagus is a broad realm almost including the total extant distribution pattern of the genus rather than a so-named center of origin. Integrated with the paleogeography, the time of origin and subsequent diversification is inferred to have started in the Late Cretaceous. Most vicariance and dispersal events should be contained in that period. Vicariance events versus dispersal events play a dominant rule in speciation. The dispersal events are hypothesized to happen from the Late Cretaceous to Eocene in terms of the geological history. Rich fossils are collected in the Eocene. South America, comprising three subgenera of Nothofagus, should be considered as a diversification region, in which the distribution of the species of subgenus Fuscospora and subgenus Nothofagus are explained by dispersal events during the Late Cretaceous-Late Eocene.
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Cited: Baidu(4)
The formation age and evolution of Kumtagh Desert
JinNian TANG, ZhiZhu SU, Feng DING, ShuJuan ZHU, YouHao E, XinWei ZHAI, ZhiYu YI, HuJun LIU, JinChun ZHANG, FaMing LI
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00114
Abstract (3279)      PDF(pc) (713KB)(4050)       Save
The ancient aeolian sand has been regarded as an indicator for the formation and evolution of a desert in the past. Kumtagh Desert is located at the northern fringe of Qinghai-Tibet Plateau. The first integrated scientific investigation to the desert was carried out during the period of 2004-2006. Kumtagh Desert is an ideal natural model for studying the formation and evolution of the desert because the Quaternary strata containing ancient aeolian sands are widely distributed. The integrated field investigation and studies on sedimentary, chronology and palynology of typical profiles named Suosuo gully, Xiaoquan gully and gravel body with ancient aeolian sand layers showed that Kumtagh Desert was probably formed as early as 2,097.7±314.7 ka BP. During the period of 386.9±58.0 ka BP to 285.9±42.9 ka BP, the desert largely expanded and formed its modern distribution pattern. The desert was originally developed in the southwest, subsequently, expanded to the north and northeast. The sedimentary facies of Suosuo gully profile revealed that the desert experienced at least 19 cycles of advance and inverse processes of desertification with an average period of 110 ka in the Quaternary. The neotectonic movements played an important role in the formation, development and geomorphology of the desert. On one hand, the movements caused the formation of intermontane fault basin, which was further developed towards the closed drought basin, and caused the formation of natural environment. On the other hand, under the control of surrounding faults, the unique broom-shaped desert landscape was formed, and the gullies and sand ridges in this region experienced an abrupt directional change from north by west to north by east at the location of 39°45′-39°55′N. The unique landscape of gravel body that occurred widely in the northern desert was formed after 285.9±42.9 ka BP. The results in this paper provide the scientific basis for studying the formation age and evolutionary process under the dry climate and environment in the northwestern China, and the uplifting of Qinghai-Tibet Plateau as well as its responses to the global climate changes.
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GSPAC water movement in extremely dry area
HongShou LI, WanFu WANG, GuoBin ZHANG, ZhengMo ZHANG, XiaoWei WANG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00149
Abstract (3165)      PDF(pc) (405KB)(2747)       Save
Under an extremely arid condition, a PVC greenhouse was built on the top of Mogao Grottoes in gobi area. The results of 235-day constant extraction of condensed water on the greenhouse film and soil water content showed that 2.1 g/(m2×d) groundwater moved up and exported into the soil, and a phreatic water evaporation existed in the extreme dry area where the groundwater is buried deeper than 200 m. After a prolonged export, the soil water content in the greenhouse was not lower but obviously higher than the original control ones. According to the monitored parameters including relative humidity and absolute humidity of soil, and temperature outside and inside the greenhouse, it was found that there is the available condition and mechanism for the upward movement of groundwater, and also it can be sure that the exported water was not from the soil and atmosphere outside the greenhouse. Phreatic water, an important source for soil water, interacts with atmosphere moisture via soil respiration. Soil salinity also has important effects on soil water movement and spatial-temporal heterogeneity. The extremely dry climate, terrestrial heat and change of upper soil temperature are the fundamental driving forces of water transportation and phreatic water evaporation in the Groundwater-Soil-Plant-Atmosphere Continuum (GSPAC) system.
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Mitigating the catastrophic impacts of torrential rivers in semi-arid environments: a case of the Gash River in eastern Sudan
Samir Mohammad Ali Alredaisy
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00174
Abstract (4097)      PDF(pc) (402KB)(3694)       Save
The climatic, geomorphic, hydrologic and aquifer characteristics of the torrential Gash River across mountainous areas, in far eastern Sudan, were analyzed in order to mitigate its recurring catastrophic impacts. Hydrologic and climatic data and interpretation of Gash River satellite images were from relevant research works carried out in Gash Basin from 1985 to 2008. The results indicated that the total catchment area of Gash River is about 21,000 km2, and the basin area is 31,000 km2. The total length of Gash River is 450 km and the average slope is 200 cm/km. The width of the catchment varies from 30 m to 90 m and that of the basin is from 100 m to 800 m, and the course of the river is varied. During the period of 1980-2008, the mean annual rainfall was 250 mm and the mean annual discharge was 6.8 × 108 m3, and the flooding is approximately one time per 5 years. Torrential floods measured at Kassala town since 1907 showed that an absolute maximum discharge was 876 m3/s and a mean maximum discharge was 365 m3/s. These characteristics differ widely between catchment and basin areas. The author proposes that, by analyzing the climatic, geomorphic, hydrologic and aquifer characteristics of the Gash River and considering the role of community, a concise database could be provided to formulate the aquifer, geomorphic, hydrologic and climatic (AQUIGEOHYCLIM) regional approach to mitigate Gash River recurring catastrophic impacts.
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Magnetic property of loess strata recorded by Kansu profile in Tianshan Mountains
Jia JIA, XianBin LIU, DunSheng XIA, HaiTao WEI, Bo WANG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00191
Abstract (3388)      PDF(pc) (406KB)(3047)       Save
Kansu (KS) profile is located in the east of Yili basin, western Xinjiang, where typical loess sediments are distributed. The magnetic parameters (such as IRM, SIRM SOFT, and M) and grain size in the KS profile were analyzed in the study. The results showed that the magnetic property of KS loess is dominated by ferrimagnetic minerals, such as magnetite and maghemite. Antiferromagnetic and superparamagnetic minerals also exist in the profile, but had less impact on magnetic susceptibility. Compared with the typical loess sediments of the central Loess Plateau in China, the strata of Kansu profile contained more magnetic minerals and hard magnetic minerals. The analysis of grain size for magnetic minerals indicated that the properties of loess and paleosol were respectively dominated by PSD/MD and coarse SSD magnetite. The research found that the contents of magnetic minerals in loess and paleosol sequences in Kansu profile were similar, but the proportion of fine grained magnetite and soft magnetic minerals were varying, which implies a positive relationship between the value of magnetic susceptibility and intensity of pedogenesis.
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Sand flux estimation during a sand-dust storm at Tazhong area of Taklimakan Desert, China
XingHua YANG, XiaoLiang XU, Qing HE, Ali Mamtimin, Bo YU, ShiHao TANG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00199
Abstract (3894)      PDF(pc) (323KB)(3539)       Save
In this paper, the sand transport during a sand-dust storm in the Tazhong area of the central Taklimakan Desert from 11:29 to 23:56 on July 19, 2008 was observed and measured in real time. The sand flux at Tazhong was estimated using sand transport empirical formulas. The critical friction velocity at Tazhong was 0.24 m/s and the functional relation between the wind speed and sediment discharge at the height of 2 m was established. It was also found that the calculated values by Lettau's sediment discharge formula were close to those of the instrument measurements. The horizontal sand flux and the vertical sand flux during this sand-dust storm at Tazhong were respectively 258.67×10-4 kg/(m·s) and 40.07×10-7 kg/(m2·s).
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Tolerance to Zn deficiency and P-Zn interaction in wheat seedlings cultured in chelator-buffered solutions
WenXuan MAI, XiaoHong TIAN, Willam Jeffery GALE, XiWen YANG, XinChun LU
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00206
Abstract (3369)      PDF(pc) (280KB)(3344)       Save
Zinc deficiency is a common constraint for wheat production in the regions with limited precipitation, particularly in the regions with high levels of available phosphate (P) in soil. Two experiments were conducted using chelator-buffered nutrient solutions to characterize differences in tolerance to Zn deficiency among three winter wheat (Triticum aestivum L.) genotypes and to investigate the relationship between P and Zn nutrition in wheat species. Four indices, Zn efficiency, relative shoot-to-root ratio, total Zn uptake in shoot, and shoot dry weight were used to compare the tolerance to Zn deficiency among three wheat genotypes. The results indicated that the four indices could be used in breeding selection for Zn uptake-efficient genotypes. The genotype H6712 was the most tolerant to Zn deficient, followed by M19, and then X13. Specifically, H6712 had the highest Zn uptake efficiency among the three genotypes. The addition of P to the growth medium increased Zn uptake and translocation from roots to shoots. Total Zn content of the wheat plant was 43% higher with 0.6 mmol/L P treatment than that of control with 0 mmol /L P treatment. The Zn translocation ratios from roots to shoots were increased by 16% and 26% with 0.6 mmol/L P treatment and 3 mmol/L P treatment, respectively, compared with 0 mmol/L P treatment. In contrast, high Zn concentrations in the growth medium inhibited P translocation from roots to shoots, but the inhibitive effects were not strong. Sixty-six percent of P taken up by wheat plants was translocated to the wheat shoots at 0 μmol/L Zn treatment, while the percent was 60% at 3 μmol/L Zn treatment. The result may be due to the fact that the wheat plants need more P than Zn.
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Temperature and precipitation trends in Minqin Desert during the period of 1961-2007
ShuJuan ZHU, ZhaoFeng CHANG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00214
Abstract (2952)      PDF(pc) (316KB)(2890)       Save
This paper analyzed the data of temperature and precipitation in Minqin, typical desert area in northwest China, during the period of 1961-2007 by linear regression. The result indicated that the increasing rate of the mean annual temperature in Minqin was higher than that of the average of China; and the temperature in February increased by 3.01oC averagely in the past 47 years. The climate in Minqin displayed an evident warming trend. However, there was no evidently increasing trend of precipitation in the past 47 years, and drought occurred during the whole growing season.
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Breeding system and its consequence on fruit set of a rare sand dune shrub Eremosparton songoricum (Fabaceae: Papilionoideae): implications for conservation
DaoYuan ZHANG, Xiang SHI, JianCheng WANG, HuiLiang LIU John F GASKIN
Journal of Arid Land    2011, 3 (4): 231-239.   DOI: 10.3724/SP.J.1227.2011.00231
Abstract (3430)      PDF(pc) (1948KB)(3936)       Save
The breeding system and its consequence on fruit set of Eremosparton songoricum (Litv.) Vass., a rare shrubby legume occurring in moving or semi-fixed sand dunes of Central Asian deserts, were examined by manipulative experiments and observational studies in natural populations during the period of 2007–2009. The results showed that E. songoricum exhibits a mixed mating system. It is self-compatible, but depends strictly on pollinators to set fruits. Only two effective pollinators were detected and they triggered the specialized pollination mechanism (a ‘brush type’ and ‘tripping mechanism’). Geitonogamy becomes predominant in natural populations, because (74.5±1.3)% of visiting activity happened within or between inflorescences and (24.3±1.4)% occurred between ramets. As a result, inbreeding depression caused by geitonogamous selfing inevitably happened under natural conditions, showing 2.36 times less fruit set than was achieved by hand cross-pollination. The results ex-plained the rarity of the species due to its breeding system, and will assist to develop suitable conservation strategies in severe desert environments.
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Monophyly and infrageneric variation of Corispermum L. (Chenopodiaceae), evidence from sequence data psbB-psbH, rbcL and ITS
JuanJuan XUE, MingLi ZHANG
Journal of Arid Land    2011, 3 (4): 240-253.   DOI: 10.3724/SP.J.1227.2011.00240
Abstract (3832)      PDF(pc) (1766KB)(6733)       Save
Corispermum is one of the most problematic taxonomic genera in Chenopodiaceae. To understand the phylogeny and infrageneric variation of Corispermum, we sequenced the nuclear ribosomal ITS region and two chloroplast DNA regions (rbcL and psbB-psbH) of 22 species and three varieties of Corispermum and the related genus Agriophyllum. Several representative species of Salsola, Suaeda, Chenopodium, Kalidium and Camphorosma served as outgroups. Our phylogenetic trees confirm that the tribe Corispermeae is monophyletic, Corispermum and Agriophyllum have a close relationship. Corispermum is demonstrated to be monophyletic, and contains at least four clades which, consequently, are served as the foundation of the infrageneric sectional variation of Corispermum, in terms of a combination of molecular data and morphological characters. The evolution of morphological characters for fruit wing and apex, two important characters in generic classification, is consistent with the sectional division of Corispermum, especially to the East Asian and Chinese taxa.
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Cited: Baidu(5)
Altitudinal patterns of stand structure and herb layer diversity of Picea schrenkiana forests in the central Tianshan Mountains, Northwest China
LiPing LI, XiangPing WANG, Stefan ZERBE, LiYun ZHANG, JingYun FANG
Journal of Arid Land    2011, 3 (4): 254-260.   DOI: 10.3724/SP.J.1227.2011.00254
Abstract (3892)      PDF(pc) (727KB)(3863)       Save
Altitude is a useful indicator to examine patterns of forest structure and species diversity in relation to environmental factors. In this study, the altitude patterns of forest stand structure and species diversity were analyzed across 20 plots in the Tianchi Nature Reserve, Northwest China. The results showed that mean stem height (Hm), maximum stem height (Hmax) and mean stem diameter at breast height (Dm) of Picea schrenkiana trees all decreased significantly with increasing altitude. Potential tree height (H*) decreased while stem taper increased significantly as altitude increased, suggesting remarkable altitudinal changes in biomass allocation between the diameter and height growth of Picea schrenkiana. Understory herbaceous richness increased significantly with increasing altitude, or with decreasing total basal area (TBA), Hm and stand volume (Volume). High light availability for understory herbs might account for the higher species richness at high altitude. Sorensen Index decreased significantly with the increase in altitude intervals, while the Cody Index demonstrated a converse pattern, suggesting greater differences in species composition with larger distances.
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