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07 June 2010, Volume 2 Issue 2 Previous Issue    Next Issue
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Research Articles
Local convergence zones or discontinuous lines in the Taklimakan Desert, Northwest China
Masatoshi YOSHINO, Takashi ISHIYAMA, Jun SUZUKI
Journal of Arid Land. 2010, 2 (2): 77-86.   DOI: 10.3724/SP.J.1227.2010.00077
Abstract ( 2743 )     PDF (1730KB) ( 2003 )  
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.
Temporal and spatial variation of annual mean air temperature in arid and semiarid region in northwest China over a recent 46 year period
ShaoYong CHEN, YuanYuan SHI, YuZhen GUO, YanXiang Zheng
Journal of Arid Land. 2010, 2 (2): 87-97.   DOI: 10.3724/SP.J.1227.2010.00087
Abstract ( 3211 )     PDF (653KB) ( 3433 )  
We analyzed the 1961–2006 mean surface air temperature data of 138 stations in China’s northwest arid and semi-arid areas (CNASA), to measure climate change in terms of annual mean air temperature changes. We used methods of linear regression analysis, multinomial fitting, Empirical Orthogonal Function (EOF), Rotated Empirical Orthogonal Function (REOF), Mann-Kendall, Glide T-examination, wavelet analysis and power spectrum analysis. The results show that (1) the warming rate of the annual mean air temperature in CNASA was 0.35oC/10a during the 1961–2006 study period. Some places in the west part of Xinjiang and east part of the Qinghai plateau, which is impacted by the terrain of leeward slope, exhibit smaller increasing trends. However, the majority of region has shown distinct warming in line with general global warming; (2) The standard deviation of the annual mean temperature distribution is non-uniform. The south Xinjiang and east Qinghai–south Gansu areas show relatively small standard deviations, but the inter-annual variation in annual mean air temperature in the greater part of the region is high; (3) Inner Mongolia, Shaanxi, Gansu, Ningxia and Tarim Basin are the areas where the temperature changes are most sensitive to the environment. The degree of uniformity in annual mean air temperature increase is higher in the arid and semi-arid area. From the early 1970s, the trend in temperature changed from a decrease to an increase, and there was a marked increase in mean temperature in 1986. After that mean temperature went through a period of rapid increase. The entire area’s 10 hottest years all occurred in or since the 1990s, and 90% of various sub-districts’ hottest years also occurred after 1990. The process of temperature change appears to have a roughly 5-year and a 10-year cycle; (4) Annual mean air temperature variation has regional differences. In Inner Mongolia–Xinjiang and Shaanxi– Gansu–Ningxia–Qinghai areas, the temperature variation in their northern areas was very different from that in their southern areas; (5) Using the REOF method we divided the region into 4 sub-regions: the Northern region, the Plateau region, the Southern Xinjiang region and the Eastern region. The region’s annual mean air temperature transition has regional differences. The Plateau and Southern Xinjiang regions got warmer steadily without any obvious acceleration in the rate of warming. The Northern region’s warming started about 5-years earlier than that of the low latitude Eastern region. The ‘Startup region’ of the Qinghai-Tibet Plateau, appears to undergo temperature changes 3 to 10 years earlier than the other regions, and exhibits inter-decadal variations 1 to 2 years ahead of the other regions.
Hydraulic resistance partitioning between shoot and root system and plant water status of Haloxyolon ammodendron growing at sites of contrasting soil texture
GuiQing XU, Yan LI, Ting ZOU
Journal of Arid Land. 2010, 2 (2): 98-106.   DOI: 10.3724/SP.J.1227.2010.00098
Abstract ( 2562 )     PDF (427KB) ( 2940 )  
Hydraulic resistance components and water relations were studied on Haloxyolon ammodendron, a small xeric tree, growing at sites significantly differed in soil texture. Soil water content, leaf water potential (ψl), xylem water potential (ψx), root water potential (ψroot), leaf transpiration rate (TR) and stomatal conductance (gs) were measured at the two sites during the growing season of 2005 and 2006. Leaf specific hydraulic resistance (Rplant) during the whole growing season, hydraulic resistance of plants (Rp), shoots (Rshoot) and roots (Rroot) in the August of both years were calculated and expressed on leaf area basis. The results showed the proportion of the hydraulic resistance of the aerial part (Rshoot) to the Rp was the same to the proportion of the hydraulic resistance of the soil part (Rroot) to the Rp, indicating that both parts were equivalent important to plant water hydraulic system from soil to leaf. Positive significant correlations were found between Rp and Rroot, suggesting that root hydraulics resistance was a major determinant of plant hydraulic resistance (Rp) and transpiration rate. The integrated effect of stomatal control, hydraulic regulation and morphology adjustment enabled plants at heavy soil site surviving the extreme water deficit period.
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. 2010, 2 (2): 107-115.   DOI: 10.3724/SP.J.1227.2010.00107
Abstract ( 3066 )     PDF (355KB) ( 2967 )  
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.
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. 2010, 2 (2): 116-122.   DOI: 10.3724/SP.J.1227.2010.00116
Abstract ( 2674 )     PDF (288KB) ( 2594 )  
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.
Ecological function regionalization of fluvial corridor landscapes and measures for ecological regeneration in the middle and lower reaches of the Tarim River, Xinjiang of China
HuaRong ZHOU, DuNing XIAO
Journal of Arid Land. 2010, 2 (2): 123-132.   DOI: 10.3724/SP.J.1227.2010.00123
Abstract ( 2948 )     PDF (218KB) ( 3213 )  
The middle and lower reaches of the Tarim River are currently one of the main regions of ecological restoration in the arid areas of western China. Using the principles and method of landscape ecology, this study has chosen the fluvial corridor landscape in the middle and lower reaches of the Tarim River, and discusses the region’s ecologically functional regionalization system and issues related to its practical classification. On this basis the corresponding regionalizing principles and standards were developed which were used to qualitatively divide the three main landscapes as the ecologically functional areas in the drainage basin. The paper has also analyzed the characteristic of the study areas, and has put forward the measures for its ecological restoration.
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. 2010, 2 (2): 133-136.   DOI: 10.3724/SP.J.1227.2010.00133
Abstract ( 2794 )     PDF (121KB) ( 3556 )  
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.
Review Articles
Nitrogen deposition as an important nutrient from the environment and its impact on ecosystems in China
XueJun LIU, Ling SONG, ChunE HE, FuSuo ZHANG
Journal of Arid Land. 2010, 2 (2): 137-143.   DOI: 10.3724/SP.J.1227.2010.00137
Abstract ( 3186 )     PDF (91KB) ( 3179 )  
As an example of atmospheric nitrogen (N) deposition, the paper summarizes the definition, form and amount of nutrient from the environment (NFE) and the relationship between NFE and anthropogenic reactive N emission. Based on our own study and published articles, we find that N wet and dry deposition has been an important nutrient resource in agricultural and natural ecosystems in China. The total amount of N deposition and other environment-derived N in China was up to 18 Tg N/a, equal to approximately 60% of the national N fertilizer consumption. Nitrogen deposition is expected to contribute substantially to nutrient cycling and net primary productivity in various ecosystems. Therefore, it is crucial to utilize this environment-derived nutrient resource by integrated nutrient resource management in order to realize the sustainable development of both agricultural and non-agricultural ecosystems.
Saline dust storms and their ecological impacts in arid regions
Jilili Abuduwaili, DongWei LIU, GuangYang WU
Journal of Arid Land. 2010, 2 (2): 144-150.   DOI: 10.3724/SP.J.1227.2010.00144
Abstract ( 3599 )     PDF (210KB) ( 4266 )  
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.
Brief Communication
Seasonal changes in the number of Relict Gull (Larus relictus) at Ebinur Lake, Western China
Ming MA, Ying CHEN, Kedeerhan BAYAHEN, BaoWen HU, Fei LI, JiaQing WU, Xiang GAO, Yu MEI
Journal of Arid Land. 2010, 2 (2): 151-155.   DOI: 10.3724/SP.J.1227.2010.00151
Abstract ( 2998 )     PDF (172KB) ( 2831 )  
The Relict Gull (Larus relictus) is recognized as a vulnerable species, with a worldwide population of about 6,000 individuals. Always inhabiting the extreme arid regions of Central Asia, their migratory routes and winter grounds are unclear. This research focused on distribution sites, habitat, behavior, population size and seasonal changes of Relict Gull. Line transects and point counts in every month were used to investigate the gulls around the Ebinur Lake. The result showed Relict Gull was summer visitor to Xinjiang, Western China. Population curve with a single peak was obtained. This gull appeared in early April and was 63 individuals (1% of the global population). The number remained stable from May to July in 2009. The discovery of fledglings indicates that Relict Gull may breed here. They left Ebinur Lake in August. Relict Gull in Ebinur Lake should belong to the Central Asian subpopulation, which was the most westerly record in China.