Table of Content

15 May 2012, Volume 29 Issue 3 Previous Issue    Next Issue

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Soil Nutrient Characteristics under Different Land Use Types in a Gully-hilly Region of the Loess Plateau XIN Zhong-Bao, YU Xin-Xiao , ZHANG Man-Liang, LI Qing-Yun, LI Hai-Guang 2012, 29 (3):  379-384.  Abstract ( 2366 )   PDF (679KB) ( 1333 )   Land degradation is an important factor restricting social and economic sustainable development in the Loess Plateau, China. In this study, a field survey was carried out to investigate the soil nutrients under different land use types (woodland, grassland, orchard, terrace and slope farmland) in the plateau. The analyzed results of 8 soil nutrient indicators at 33 sample sites showed that the effects or impacts of different land use types on soil erosion were quite different, especially for the indicators, such as soil organic matter content, total nitrogen content and available nitrogen content. The soil organic matter content and total nitrogen content were in an obvious order of woodland > slope farmland ≈ terrace > orchard > grassland, the available P content was in an order of orchard > slope farmland > terrace > woodland > grassland, and the available P content under crops was obviously higher than that under natural vegetation. The study results revealed that terrace, as a traditional soil conservation practice, could perform very well in conserving soil nutrients, but the soil conservation capability of slope grassland was the poorest in the gully-hilly region of the Loess Plateau. References | Related Articles | Metrics

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Research on Soil Erosion and Regional Differentiation of Forestland in the Jinghe Watershed GENG Yan-Hui, 吕Ai-Feng , MIN Qing-Wen, HE Yong-Tao 2012, 29 (3):  385-392.  Abstract ( 1700 )   PDF (4213KB) ( 1028 )   Located in the Loess Plateau, the Jinghe Watershed is an arid and semiarid area, where land use structure is dominated by grasslands with moderate or low vegetation coverage, and hilly farmland is an important factor resulting in severe water loss and soil erosion in the drainage basin. Therefore, the emphases of its ecological construction are to convert land for farming to forests or grassplots and improve vegetation coverage of the grasslands. According to the match degree of ecological water requirement of the local forestlands and local precipitation in growing season, in this paper, the Jinghe Watershed was divided into three kinds of areas: suitable or relatively suitable forestlands, relatively unsuitable forestlands, and unsuitable forestlands. The research results show that the three kinds of areas are distributed as sloped belts from northeast to southwest, and proportions of their areas were 53.69%, 22.16% and 24.15% of the total respectively. The climate change effects on regional differentiation of vegetation were analyzed. Precipitation in growth season of forestlands during the periods of 1961-1980 and 1981-2004 was compared and evaluated, and the corresponding change of regional differentiation of vegetation in the watershed was researched. It was found that precipitation in growth season of forestlands was in a decrease trend in most area of the Jinghe Watershed, and the most decrease was about 50 mm. Owing to the impact of precipitation change, the unsuitable and relatively unsuitable forestlands  were expanded southeastward, and the area of suitable or relatively suitable forestland was reduced by 11.4%. The study results can be referred  for regenerating local vegetation. References | Related Articles | Metrics

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Effects of Super Absorbent Polymer on Soil Moisture Content and Spring Wheat Growth in the Hetao Irrigated Area BAI Gang-Shuan, ZHANG Rui, GENG Gui-Jun, DU She-Ni, YU Jian 2012, 29 (3):  393-399.  Abstract ( 1820 )   PDF (1357KB) ( 924 )   In order to promote the extension of super absorbent polymer, this paper evaluates some effects of super absorbent polymer BJ2101-L, soil structure improver PAM and BJ2101-L+PAM on soil moisture content and spring wheat growth in the Hetao irrigated Area, Inner Mongolia. The soil moisture content under the super absorbent polymer treatment was higher than that of the contrast case, especially at fringe-forming stage, and the soil moisture content under the BJ2101-L treatment was increased by 14.26% in soil layer of 0-80 cm in depth. Super absorbent polymer could be used to improve spring wheat tillering and root growth in deeper soil. The tillering capability of spring wheat under the PAM treatment could be increased by 60.45% compared with that of contrast case, and the distribution depth of wheat roots under the BJ2101-L treatment could be increased by 70.79%. Biomass and grain yield of spring wheat under BJ2101-L treatment were increased by 27.24% and 30.96% respectively compared with those of contrast case. Water use efficiency, water productivity efficiency and irrigation water productivity efficiency under the BJ2101-L treatment were increased by 20.58%, 24.13% and 31.00% respectively. BJ2101-L treatment could be used to significantly improve the economic returns per unit area, but the PAM treatment reduced significantly the economic returns. Super absorbent polymer should be actively applied in spring wheat production in the Hetao Irrigated Area, Inner Mongolia. References | Related Articles | Metrics

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Application of RBF Network for Calculating Desert Soil Evaporation in the QinghaiTibetan Plateau WANG Xue-Quan, LIU Jun-Mei, YANG Heng-Hua, ZHAO Xue-Bin, CHEN Qi 2012, 29 (3):  400-404.  Abstract ( 1767 )   PDF (816KB) ( 1069 )   Evaporation is an important factor affecting thermal balance and water budget over the earth surface. A long-term observation of soil evaporation over semifixed dune was carried out with micro-lysimeters (MLS) in the high-frigid regions in the Qinghai-Tibetan Plateau of China during the period of 2006-2009, the dataset was consisted of the collected daily soil evaporation as the output and the corresponding meteorological observation data including relative air humidity, air temperature, wind speed and soil moisture content as the input. A desert soil evaporation model was developed to research soil evaporation over semi-fixed dune based on the radial basis function (RBF) neural network, and the multiple linear regression (MLR) was used to validate the model. The results show that the values calculated with RBF network output were consistent with the observed values, and the root mean squared error was 0.14 mm. Both the average absolute percent error and the root mean squared error for the RBF neural network were lower than those for the MLR model. The RBF neural network model is good for calculating desert soil evaporation other than the traditional mathematica1 evaporation model, and it is characterized by the simple development, high accuracy and strong adaptability. References | Related Articles | Metrics

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Study on Soil Enzyme Activity in the Marginal Zone of the Ganjiahu Wetland in Xinjiang MA Xiao-Fei, LI Yan-Hong, YANG Ai-Xia, CHU Xin-Zheng 2012, 29 (3):  405-412.  Abstract ( 3068 )   PDF (2500KB) ( 1361 )   In this study, the activity of 4 soil enzymes affected strongly by different vegetation communities, anthropogenic factors and murine in the marginal zone of the Ganjiahu Wetland was lucubrated. The results are as follows: (1) The activity of urease and catalase was in an order of Phragmites australis community > Populus euphratica community > Holoxylon ammodendron community > Aneurolepidum chinense community, that of proteinase in an order of A. chinense community > P. australis community > P. euphratica community > H. ammodendron community, and that of sucrase in an order of P. australis community > H. ammodendron community > P. euphratica  community > A. chinense community; (2) Temporally, the maximum values of urease, catalase and proteinase contents occurred in August, and the minimum ones in May or October, but the maximum value of sucrase content occurred in May, then it was decreased gradually, and increased to some extent in October; (3) Vertically, urease and proteinase contents in P. australis  and H. ammodendron communities were decreased with the increase of soil depth, but the sucrase content was decreased at first and then increased with the increase of soil depth; (4) Linear regression analysis revealed that total N and organic matter content were the important factors affecting soil enzymatic activity; (5) Impact of trample on soil enzyme activity was serious, reclamation could increase the activity of these enzymes, especially that of urease and catalase. Impact of grazing on urease and proteinase was also serious. In addition, all the peak values of urease, catalase, proteinase and sucrase occurred in August; (6) The contents of urease, catalase, proteinase and sucrase were low in the areas with mice destruction compared with that in the micefree areas, especially the content of urease. The increase rates of activity of these enzymes in the areas with mice destruction were lower than those in the micefree areas during the period from May to August. References | Related Articles | Metrics

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Research on Change and Periodicity of Annual Runoff Volume along the Ningxia-Inner Mongolia Section of the Yellow River LIU Jun-Qiu, SHI Wen-Juan 2012, 29 (3):  413-418.  Abstract ( 2588 )   PDF (1557KB) ( 1759 )   In this paper, the change and periodicity of average annual runoff volume and its main affecting factors along the Ningxia-Inner Mongolia section of the Yellow River were lucubrated based on 46-year (from 1961 to 2006) average annual runoff volume data measured at Qingtongxia and Toudaoguai hydrological stations, and the multi-temporal scales were analyzed. The results show that the change of average annual runoff volume at these two stations at different temporal scales was synchronicities. After analyzing the wavelet variance plots, it was found that there were 18-year and 31-year periodic fluctuations of annual runoff volume. The results were tested and verified with the process line of the real part of wavelet to obtain the change trend of annual runoff volume at these two stations, and it was predicted that a low flow will continue along the Ningxia-Inner Mongolia river section in next few years. Reduction of annual runoff volume of the river section was mainly caused by the decrease of precipitation, increase of water consumption and operation of reservoirs. The study results can provide the references for conserving water resources, controlling sediment and predicting annual runoff volume along the Ningxia-Inner Mongolia section of the Yellow River. References | Related Articles | Metrics

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Elicitation of Management Mode of the Murray-Darling Basin in Australia to that in China SHI Xuan, ZHAO Zhi-Xuan, LI Li-Xin, GENG Si-Min, WANG Qing 2012, 29 (3):  419-424.  Abstract ( 4017 )   PDF (1266KB) ( 1265 )   To deal with the challenges of severe drought and some problems of water resources utilization, a comparatively sound management mode was formed for managing the Murray-Darling Basin in Australia. The successful experience includes: stress on basin scale management; threelayer organizational coordination system of MDBMC (Murray-Darling Basin Ministerial Council), MDBC (Murray-Darling Basin Commission) and CAC (Community Advisory Council); marketization with cap’s principle and water right transaction; and sound river basin management law system on the basis of agreement between states. Learning from the successful river basin management experience, the concept of sound river basin management and elaboration of the pattern of public participation in organizational framework setting should be fully expressed combined with the actuality of river basin management in China, the basinscale management should be emphasized, and the power of river basin management committees should be strengthened through provincial agreement; the function of market economy in basin management should also be strengthened. In addition, it is necessary to complete the legal system of river basin management so as to guarantee the application of sound river basin management. References | Related Articles | Metrics

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Analysis on Plant Functional Traits of Populus Species in the Tianshan Mountains XU Qing-Hua, ZANG Run-Guo, XIE Huai-Ci, BAI Zhi-Qiang, GUO Zhong-Jun, ZHAO Ling 2012, 29 (3):  425-431.  Abstract ( 2216 )   PDF (1893KB) ( 1062 )   Plant functional traits can help us to deduce plant life history strategies and enhance our understanding to ecosystem functions. In order to study the ecological strategies of adapting environment of 4 Populus species in north slope of the Tianshan Mountains, the differences in functional traits of leaves, stems and roots among Populus alba, P. nigra, P. russkii and P. euphratica were researched. The results show that the leaf size, leaf thickness, leaf dry matter content, stem tegument thickness, wood density and nutrition content of organs were significantly different among the 4 species, but the difference of specific leaf area was not significantly. Among the 4 species, both leaf area and leaf dry matter content of P. alba were the highest, both leaf thickness and wood density of P. euphratica　were the highest, and stem tegument thickness of P. nigra was the highest. Content of N in leaves of the 4 species was higher than that in stems and roots, the difference of N and P contents between stems and roots was not significant, contents of K in leaves, stems and roots of the 4 species were quite different; except P. euphratica, content of P in leaves was higher than that in stems and roots; contents of N, P and K in P. nigra were the highest, but those in P. russkii were the lowest. Variation of the functional traits of the 4 Populus species reflected their adaptation to environment. References | Related Articles | Metrics

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Strategies for Biomass Allocation of Two Desert Plant Species under Water Stress CHENG Jun-Hui, ZHANG Yuan-Ming 2012, 29 (3):  432-439.  Abstract ( 1854 )   PDF (3862KB) ( 1141 )   Water stress is one of the main driving forces to affect the structure and function of ecosystem in arid and desert regions. The objective of this study was to analyze the relationship between aboveground and belowground biomass of two desert plant species at their growth stages under water stress. The processes of biomass accumulation and allocation of Malcolmia africana and Ceratocarpus arenarius at their growth stages were researched by pot experiment. Three water supply treatments, i.e. the water-control treatment (CK), moderate water stress (LW1) and severe water stress (LW2), were applied in the experiment. The results showed that whether there was water stress or not, the accumulation of total biomass was fitted well by Sigmoidal growth model. The effect of water stress on total biomass accumulation was not obvious at early growth stages, but was significantly reduced at late stages. The proportions of leaves in total biomass of M. africana and C. arenarius were decreased by 8.9%-10.6% and 3.1%-3.4% respectively with the plant growth every 10 days, which were almost equal to the increased proportion of stems. Water stress could significantly increase root biomass, but the total biomass accumulation was still dominated by the increase of aboveground biomass. There were four visible stages of rootshoot ratio change during the whole growth stage of these two plant species. References | Related Articles | Metrics

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Research on Drought Resistance of Three Plant Species in Ecological Regeneration on Rocky Slope under Drought Stress ZHOU Jiang, PEI Zong-Ping, HU Jia-Jia, JIA Han-Shuai, ZHU Lin 2012, 29 (3):  440-444.  Abstract ( 1665 )   PDF (1213KB) ( 1145 )   Drought resistance of plants affects directly the final result of ecological regeneration on rocky slope. In order to research the mechanism of drought resistance of different plants under sustained drought, three plant species including Poa pratensis, Cynodon dactylon and Trifolium pratense,common in the ecological regeneration on rocky slope, were selected to research the changes of 6 drought resistance indexes including the relative water content, relative conductivity, contents of malondialdehyde, soluble carbohydrate, proline and chlorophyll of the plant leaves with pot culture experiments and chemical analysis. The results showed that all the physiologic and biochemical indexes of the plants changed in varying degrees under drought stress. Fuzzy membership function analysis and the grey correlation analysis were used to research the drought resistance of the 3 plant species and the sensitivity of 6 drought resistance indexes to drought stress. The results revealed that the drought resistance of the 3 species was in an order of C. dactylon ＞ T. pretense ＞ P. prarensis at the early and middle drought stages, but in an order of P. prarensis ＞ C. dactylon ＞ T. pretense at the late stage. The correlation degrees between the 6 drought resistance indexes and the membership degrees were in descending order of 0.708, 0.694, 0.638, 0.630, 0.609 and 0.607, so they can be accepted as the indexes of evaluating and selecting the droughtresistant plant species for ecological regeneration on rocky slope. Among these indexes, chlorophyll and relative water content of plant leaves are the most sensitive to drought stress.   References | Related Articles | Metrics

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New Progress of the Studies on Vegetation over Inter-dune Lowland WANG Yong-Cui, JIANG De-Ming, TOSHIO Oshida 2012, 29 (3):  445-449.  Abstract ( 2059 )   PDF (644KB) ( 1015 )   Inter-dune lowland is characterized by its small size, obvious spatiotemporal variation and complex ecological process, and the relationships between vegetation and environmental factors attract the attention of ecologists all over the world all along. We searched the papers about vegetation process over inter-dune lowland from CNKI and Web of Science, and the information of vegetation and soil seed bank survey methods were summarized. It is considered that following aspects need to be further studied: (1) Study on vegetation process over inter-dune lowland in semiarid region; (2) The consistent vegetation survey methods; (3) More detailed knowledge about the dispersal and growing conditions of rare and dominant plants; (4) The effect of grazing on vegetation process over inter-dune lowland. References | Related Articles | Metrics

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Study on Features of Avifauna in the Ordos Plateau in Inner Mongolia YANG Fan, YANG Gui-Sheng, XING Pu, XU Ying, XING Lian-Lian 2012, 29 (3):  450-456.  Abstract ( 2784 )   PDF (916KB) ( 1134 )   In this study, the transect method and fixed-radius sample plot method were used to carry out the detailed surveys on birds in the Ordos Plateau in Inner Mongolia in 2005 and during the period of 2008-2009. During the investigations, 168 bird species in 14 orders and 39 families were recorded. Among them 31 species were residents, 73 species summer visitors, 60 species migrants and 4 species winter visitors. There were 104 species of breeding birds, and they had significant advantages and constituted the main body of avifauna.  There were 92 middle- and northern-boundary breeding bird species, accounting for 88.5% of the total, and the northern-boundary species was absolutely dominant. The elements of Palaearctic realm played the important roles in the avifauna. Among the birds, 5 species were listed as national firstgrade protected wildlife in China, and 21 species as the second-grade ones. There were 5 kinds of habitats in the study area, i.e. the forestlands, thicket grasslands, wetlands, farmlands and residential areas. Survey results revealed that human activities affected significantly the birds avifauna. References | Related Articles | Metrics

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Spatial Distribution of Water Vapor Content over the Qinghai-Tibet Plateau in Summer HAN Jun-Cai, ZHOU Shun-Wu, WU Ping, WANG Chuan-Hui, YANG Shuang-Yan, YANG Ming 2012, 29 (3):  457-463.  Abstract ( 2053 )   PDF (2256KB) ( 1054 )   Based on the sounding data from 14 sounding stations over the Qinghai-Tibet Plateau during the period of 1979-2008 and the NCEP/NCAR reanalysis data in recent 30 years, the spatiotemporal distribution of water vapor content over the plateau in summer and the factors affecting abnormal water vapor content were analyzed using the means of linear trend method, Mann-Kendall test and composite analysis. The results show that water vapor content over the plateau in summer was decreased with the increase of altitude, namely water vapor content was high over the southeastern and northeastern parts of the plateau but low over the northwest part; On the whole, water vapor content over the plateau in summer was in an increase trend in recent 30 years, especially over the arid western region. The characteristics of the years with high (or low) water vapor content over the plateau in summer were as follows: （1） Water vapor flux was converged (or diverged) in the years with high (or low) water vapor content; （2） The potential height of water vapor content over the low-level plateau was in a negative (or positive) anomaly in the years with high (or low) water vapor content; （3） Surface temperature was higher (or lower) in the years with high (or low) water vapor content. References | Related Articles | Metrics

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Spatiotemporal Distribution of Snow Cover in Arid Regions in China WANG Zeng-Yan, CHE Tao 2012, 29 (3):  464-471.  Abstract ( 1869 )   PDF (2271KB) ( 927 )   Based on MODIS and AMSR-E combined cloud-free snow cover product, in this paper the snow cover duration days(SCD), snow cover onset date (SCOD) and snow cover ending date(SCED)  in arid regions of China were calculated and evaluated for 8 hydrological years from 2002 to 2009. Spatiotemporal distribution of snow cover in the study area was analyzed through mapping of SCD and statistical results of snow cover area (SCA). The results are as follows: (1) The compared results reveal that the accuracy of snow cover parameters extracted from remote sensing images is high and close to the data observed at the weather stations, the duration errors are mostly within 20 days; (2) Except for the regions covered with glaciers and firn in the alpine zone, north Xinjiang between the Tianshan Mountains and Altay Mountains is the region with the thickest seasonal snow cover, SCD was mostly longer than 60 days, but the distribution of seasonal snow cover is uneven. Holistically, the SCD becomes shorter, the SCOD becomes later and SCED becomes earlier from the marginal zone of the mountains to the central area of the basins; (3) The total areas of snow cover in arid regions were comparatively large in 2005, 2007 and 2002 but small in 2008 and 2006, respectively; The area and distribution of stable snow cover were comparatively stable, with the inter-annual changes being mainly the fluctuation of the number of SCD; the area of unstable snow cover were generally larger than stable snow cover, with obvious inter-annual fluctuations and the number of SCD mostly lower than 20. References | Related Articles | Metrics

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Analysis on Features of Regional and Continuous Drought in North Xinjiang in Spring and Summer ZHAO Yong, YANG Qing, MA Yu-Fen 2012, 29 (3):  472-478.  Abstract ( 1880 )   PDF (2065KB) ( 1166 )   As a kind of climate disaster, drought causes big economic loss, especially the big agricultural loss, it is meanwhile known to be such a complex natural hazard and also much more severe than any other natural extreme events. As the most frequent and serious meteorological disaster in Xinjiang, drought is characterized by vast disaster area and long duration. Therefore, it attracts more and more attention of meteorologists to study drought. Precipitation in north Xinjiang, 200 mm approximately, is much higher than that in south Xinjiang (about 50 mm), and utilization of the unified criteria to estimate the distribution of drought in these two distinguish regions is undoubtedly improper, so this paper focuses mainly on the variation of drought features in north Xinjiang (excluding the Tianshan Mountains). The previous researches focused mostly on seasonal change of drought, but few studies focused upon its regional and continual features. Complex topography induced dominantly the significant climatic difference between different regions and different seasons in north Xinjiang. Therefore, it is an issue worthy to lucubrate that how to analyze qualitatively the spatial features and time response of drought distribution. In this paper, the features of regional and continuous drought over the Junggar Basin in north Xinjiang in spring and summer were analyzed based on the daily precipitation data observed by 36 meteorological stations in Xinjiang during the period of 1961-2007. The results revealed that the extreme drought occurred most frequently in the basin, especially in northwest Xinjiang, where spring drought occurred every 3 years, but summer one occurred every 4-5 years. The probability of interseasonal draught occurrence was lower (<10%), while the occurrence of inter-monthly continual draught was much more common, and the occurring frequency of 2-month continual draught was approximately 20% of the total. The analyzed results showed that the continual draught occurred most frequently in May and June in northwest Xinjiang. Spring draught was much more common than that of summer one in the Ili River Valley and north Tianshan Mountains as well as the northern part of north Xinjiang, and the extreme draught occurred most frequently in the north Tianshan Mountains. Draught intensity in the three regions was in a decrease trend. Spring drought frequency was low in the late-1990s, and summer one was low in the late1980s. References | Related Articles | Metrics

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RS-based Estimation of Evapotranspiration in the Yarkant Oasis YANG Hong-Juan, CONG Zhen-Tao, ZHAO Yan, CHEN Jun-Peng 2012, 29 (3):  479-486.  Abstract ( 1919 )   PDF (2349KB) ( 903 )   In this paper, the values of latent heat flux were estimated for the Yarkant Oasis using the coupled algorithm of the harmonic analysis method, two-source energy balance (TSEB) model and MODIS data. The instantaneous evapotranspiration (ET) was extended to daily, monthly and annual scales. The spatiotemporal distribution of water consumption in the oasis in 2007 was analyzed. Water consumption proportions of different land use types were also calculated. In remote sensing method, though the surface energy balance was considered only, the differences between the simulated results of annual water consumption over the oasis and the values computed with water balance equation were low. Mean simulated annual ET results approximated to the values estimated with the runoffevaporation hydrological model for all the land use types. The results reveal that the ET model used in this paper can be used for researching water consumption in oasis, and the estimated results can provide scientific basis for redistributing water resources in the Yarkant Oasis. References | Related Articles | Metrics

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Analysis on Precipitation in Altay Prefecture, Xinjiang ZHUANG Xiao-Cui, YANG Sen, ZHAO Zheng-Bo 2012, 29 (3):  487-494.  Abstract ( 2288 )   PDF (2574KB) ( 987 )   This paper focused on precipitation in Altay Prefecture, Xinjiang based on the monthly precipitation data during the period from 1961 to 2009 and from January to March 2010, and the Mann-Kendall trend test, cubic function, Mann-Kendall sharp change check, R/S analysis and Morlet wavelet transformation analysis were used in the study. The results are as follows: (1) Annual and winter precipitation was significantly increased, and the change of precipitation in other seasons was not obvious; precipitation  was quite different from different regions; the linear trend of precipitation was consistent with the Mann-Kendall trend change; (2) The fitting results of cubic function revealed that the annual, spring and winter precipitation was monotonously increased, and such change occurred from the 1960s; summer precipitation was increased at first, then decreased, increased and decreased again; the variation of autumn precipitation was not significant, and the spatiotemporal distribution of precipitation was quite different from different regions; (3) Annual and summer precipitation was sharply increased around 1983 and 1987 respectively, the sharp change of spring and autumn precipitation was not significant, and there was no sharp change of winter precipitation; the sharp change time of precipitation was inconsistent; (4) There was a significant periodic change of annual and seasonal precipitation at inter-decadal and inter-annual scales; (5) There was an anti-continuance of precipitation. References | Related Articles | Metrics

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Distribution and Change of Different Precipitation Pulse Sizes in the Southern Marginal Zone　of the Junggar Basin, China ZHENG Xin-Qian, ZHENG Xin-Jun, LI Yan 2012, 29 (3):  495-502.  Abstract ( 2541 )   PDF (3473KB) ( 1014 )    The “pulsereserve” conceptual model was one of the most-cited paradigms to study the eco-process triggered by precipitation pulse in water-controlled ecosystem in the past decades, giving people a new scope to understand the relationship between precipitation and structure and function of desert ecosystem in arid area. In this paper, different sizes of precipitation pulse events contributing to annual precipitation and its frequency as well as its change in the marginal zone of the Junggar Basin, China were analyzed based on the daily precipitation data observed at 6 meteorological stations in the study area. The results showed that the proportion of low precipitation pulse event size (lower than or equal to 5 mm) was as high as 87.5%, while that of high one (higher than 10 mm) was only 4.3% of the total annual precipitation pulse frequency. However, the contribution rates of low and high precipitation pulse event sizes to annual precipitation were 47.5% and 26.6% respectively. In the past 50 years, annual precipitation was increased significantly, but the change of annual precipitation frequency was not significant. It could be explained that the low precipitation pulse event size was in a decrease trend, but the high one was in a significant increase trend. Anyway, the precipitation pulse event sizes in the marginal zone of the Junggar Basin were amplified in the past 50 years. References | Related Articles | Metrics

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Analysis on Change of Sunshine Duration in Hebei Province during the Period from 1961 to 2010 XIANG Liang, HU Bo, GU Yong-Li 2012, 29 (3):  503-509.  Abstract ( 1779 )   PDF (4224KB) ( 1020 )   In this paper, the change of annual sunshine duration in Hebei Provinc during the period of 1961-2010 was analyzed using EOF, maximum entropy spectrum and Lepage test. The results showed that the difference of spatial distribution of annual sunshine duration was significant in the province. Holistically, annual sunshine duration was decreased from the north to the south of the province, it was in a downtrend in most areas of the province, the downtrend was more obvious in most parts of the central-southern area than that in most parts of the northern area, and the downtrend of annual sunshine duration was extremely significant. The spatial distribution of annual sunshine duration was not only similar, but also varied from the south to the north. Temporally, the decrease of annual, seasonal and monthly sunshine duration was extremely significant except that in few months. Lepage test revealed that there was a sharp change of annual sunshine duration in 1972 and 2001. The analyzed results also showed that the there was a significant change and 4.2year periodicity of annual sunshine duration in the province. The further analyzed results revealed that the main factors resulting in the reduction of annual sunshine duration was cloud cover and fog, and floating dust was not the main reason causing the reduction of annual sunshine duration. References | Related Articles | Metrics

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Factor Decomposition and Demonstration Analysis of Carbon Emission Variation in Gansu Province LIU Ding-Hui, YANG Yong-Chun 2012, 29 (3):  510-516.  Abstract ( 1712 )   PDF (2707KB) ( 934 )   It is important to investigate the characteristics and mechanisms of energy-related carbon emission and provide the meaningful reference for formulating the rational strategy of carbon emission reduction. The aim of decomposition analysis is to reveal the importance of distinct components or factors related to historical carbon emission data. A calculation method was used to compute the values of energy-related carbon emission and analyze the historical change of carbon emission of 6 sectors in Gansu Province during the period of 1995-2009. It was found that the total energy-related carbon emission was increased from 9.46×106 t in 1995 to 1.57×107 t in 2009, the average annual increase rate was 3.66%, and it was lower than the average in China and also the values of some provinces and big cities in east China, such as Beijing, Shanghai and Jiangsu. Extended Kaya identity was used to develop a factor decomposition mode and decompose the change of total energyrelated carbon emission into the components of economic scale, population size, industrial structure, energy intensity and energy structure. Based on the time series decomposition of Logarithmic Mean Divisia Index (LMDI), the change of energy-related carbon emission during the period of 1995-2009 in Gansu Province was analyzed. Empirical results demonstrated that economic scale was dominant in the increase of carbon emission in Gansu Province, then the population sizes and industrial structure. Sectoral decomposition showed that the effect of economic growth on carbon emission increase was more significant than that of industry and traffic sectors. It was found that the main factors of restricting the increase of carbon emission are the decrease of energy intensity and the change of energy structure. Some policy suggestions were put forward for reducing carbon emission in Gansu Province in the future． References | Related Articles | Metrics

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Research on Wind Profile and Sand Drift Structure in Guaizi Lake Region in the Badain Jaran Desert HE Qing, HU Wen-Feng, YANG Xing-Hua, AI Li-·Mai-Mai-Ti-Ming, ZHAO Cong-Min 2012, 29 (3):  517-523.  Abstract ( 1996 )   PDF (1320KB) ( 1093 )   A field monitoring test was carried out in Guaizi Lake region in the Badain Jaran Desert so as to study the wind profile and sand drift structure in the region. The Analyzed results reveal that both free wind and sand drift profile can be scattered by Z=A·exp(-X/T)+Z1but the fitted coefficient of sand drift was higher. In the sand drift structure, the percentage of sand transport rate, sand concentration and energy of moving particles were all in an increase trend with the increase of height below 20 cm from the ground. The percentage of sand transport rate at all the heights was decreased with the increase of height above 20 cm, the proportion of sand transport rate was about 51% of the total, and sand drift occurred mainly in an air layer below 20 cm from the ground. Vertically, there was a negative correlation between average particle size and height, but a positive one between average particle size and wind velocity. These conclusions are of great guiding importance for constructing windbreak against sand drift in the Guaizi Lake region. References | Related Articles | Metrics

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Analysis on Aerodynamic Roughness Length in a Desert Transitional Zone of the Taklimakan Desert YANG Xing-Hua, AI Li-·Mai-Mai-Ti-Ming, ZHANG Rui-Jun, HE Qing, HUO Wen 2012, 29 (3):  524-528.  Abstract ( 1972 )   PDF (1105KB) ( 939 )   In this paper, the values of aerodynamic roughness length over the Hade and Xiaotang regions were calculated under the conditions when the atmospheric stability was in a neutral stratification and there was no windblown sand movement using the wind speed ratio method based on the data of average wind speed and temperature obtained from 10-m-high towers at Hade and Xiaotang in a desert transitional zone of the Taklimakan desert. The correlations between aerodynamic roughness length and underlaying surface, air stability and wind speed were analyzed and discussed. The results are as follows: The aerodynamic roughness length z0of neutral stratification was in ranges of 1.81×10-11-1.2×10-3　m and 1.00×10-11-1.65×10-3　m, their average values were 2.70×10-5　m and 6.05×10-5　m, respectively, and these values were close to those over flat sand surface. The aerodynamic roughness length z0changed obviously with the change of underlaying surface features. On the whole, the value of aerodynamic roughness length was increased with the increase of atmospheric stability, while the discrete degree of aerodynamic roughness length was increased. There was a significant negative exponential relation between aerodynamic roughness length and wind speed at 2m height. Atmospheric stability has a complex influential action on aerodynamic roughness length, which needs to be further studied. References | Related Articles | Metrics

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Analysis on Wet Deposition in Urumqi during the Period from 2000 to 2009 WEI Jiang 2012, 29 (3):  529-533.  Abstract ( 1633 )   PDF (1239KB) ( 859 )   Based on the monitoring date of acid deposition in Urumqi during the period from 2000 to 2009, in this paper the main characteristics of wet deposition were analyzed. The results show that wet deposition pollution was serious in Urumqi. Except the wet nitrogen deposition flux was 1.06 g·m-2and similar to the average of whole China, wet sulfur and calcium deposition fluxes were 3.21 g·m-2and 3.22 g·m-2 respectively and higher than those in other provinces and cities in China. Wet sulfate deposition in Urumqi came mainly from the local SO2 sources, it became more and more serious in recent years, the contribution of nitrogen deposition to the total wet deposition was in an increase trend, and the decrease of wet calcium deposition may result in a more serious acidification of wet deposition. References | Related Articles | Metrics

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Analyses on Factors Affecting Ecological Environment Change in South Xinjiang LI Xin-Hua 2012, 29 (3):  534-540.  Abstract ( 1767 )   PDF (1228KB) ( 1096 )   By virtue of previous studies and environmental monitoring data, this paper discusses the main ecological environmental problems in south Xinjiang in recent years, and analyzes the factors affecting these problems. The results show that the environmental change in south Xinjiang is affected by both natural and human factors. The natural factors are mainly precipitation, temperature, occurring frequency and intensity of dust weather, water resources, etc. Furthermore, climate change in this region is characterized by the increase of both temperature and precipitation and the decrease of occurring frequency of dust weather. The human factors are mainly characterized by environmental pressure that comes from continuant population growth, excessive exploitation of water and land resources, rapid development of urbanization and industrialization, etc. However, rational exploitation of water and land resources may bring about the positive effects to ecological environment, such as the improvement  of local climate, reduction of aridity and sandstorm disasters, control of land desertification, and improvement of service functions of artificial oasis ecosystem. Therefore, the change of natural factors and the disturbance of human factors can bring about positive and negative effects to the development of ecosystems in south Xinjiang.  References | Related Articles | Metrics

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Study on Relationship between Flood Disasters and Ecoentironment in the Lower Reaches of the Weihe River since Historical Periods LIU Jian-Fang, CHA Xiao-Chun 2012, 29 (3):  541-546.  Abstract ( 1773 )   PDF (1456KB) ( 1211 )   Flood disasters have occurred for several times in the lower reaches of the Weihe River since recent 30 years and resulted in enormous destruction. It is more and more necessary to deeply research the occurring laws of flood disasters in the study area. In this paper, the change in flood disasters during the period from 170 BC to 1992 AD was analyzed based on the historical flood disaster records in the lower reaches of the Weihe River. The results show that 243 flood disasters were recorded in the lower reaches of the Weihe River, in which they occurred less frequently before 630 AD but more frequently after that. From 1920, flood disasters occurred more and more frequently, but they reduced to some extent  after 1960. According to the historical data, fluctuation of the occurring frequency of flood disasters could be divided into 7 periods, the relationship between flood disasters and entironment evolution was analyzed, and the results show that the occurrence of flood disasters during the historical periods was directly related to the entironment evolution in the drainage basin. Therefore, it is very important for reducing flood disasters to intensify the entironment construction in the drainage basin. References | Related Articles | Metrics

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A Method for Determining Necessary Sample Size in Random Sampling and Its Application YAO Shu-Xia, ZHANG Tong-Hui 2012, 29 (3):  547-552.  Abstract ( 2834 )   PDF (717KB) ( 3773 )   The sample average is usually used to estimate the holistic average in random sampling of an ecological survey. However, determination of sample size plays an important role in calculating the sample average. Based on the statistical theory, a method of determining the necessary sampling size in random sampling in the Horqin Sand Land was obtained, and it was tested with some data sets, such as the contents of soil moisture, soil organic matter, nitrogen, phosphorus and potassium, composition of plant species, and vegetation height, density and coverage. The necessary sample sizes for these ecological indicators were obtained. As the values of cv (coefficient of variation) of these indicators were lower than the assumed values, the results are as follows: (1) The necessary sample sizes for the contents of soil organic matter, total nitrogen, available nitrogen, total phosphorus, available phosphorus and potassium in cropland ranged from 7 to 15; (2) The necessary sample sizes for the height, density, coverage and species composition of vegetation over fixed dunes and sandy grasslands were 11, 8, 28 and 15 respectively; (3) The necessary sample sizes for soil moisture content of fixed and semifixed dunes in depth 0-30 cm were 32 and 12 respectively. These results are of certain guiding and referring value for rationally selecting the sample sizes in the Horqin Sand Land and similar regions in the future. References | Related Articles | Metrics

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Preliminary Study on the Effects of Ecological Conservation on Material Benefits of Local Residents in Guyuan City, Ningxia Hui Autonomous Region PAN Ying, ZHEN Lin, YANG Li, LONG Xin, CAO Xiao-Chang 2012, 29 (3):  553-560.  Abstract ( 1754 )   PDF (2458KB) ( 1027 )   In this paper, the effects of ecosystem conservation policy on material benefits of local residents in Guyuan City of Ningxia Hui Autonomous Region were studied. Patterns and variations of five ecosystem services under the ecosystem conservation policy were analyzed based on the land use data, statistic data and household survey data during the period from 1995 to 2005. The five ecosystem services were the food supply, energy supply, water conservation, job opportunities and income sources. Material benefits of local residents were quantified by comparing the ecosystem services with the human need and consumption to ecosystems. Integrated with the land use change data, the effects of ecosystem conservations on the material benefits of local residents were assessed. The results show that the material benefits of local residents in Guyuan City was increased significantly during the period from 1995 to 2005, especially the improvement of farmers' income and food supply. In detail, 70.4% increase of material benefits of local residents depended on the grain yield increase of arable land, and 24.0% was brought about the ecosystem conservation; 26.9% increase of material benefits of local residents came from the subsidies of the project of converting land for farming to forests (or grassplots), and 70.5% was brought about the improvement of water conservation capability. References | Related Articles | Metrics