Table of Content

15 September 2012, Volume 29 Issue 5 Previous Issue    Next Issue

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Natural Regeneration of Plantation Forests under Drought WANG Han-Sheng 2012, 29 (5):  743-750.  Abstract ( 1880 )   PDF (972KB) ( 1092 )   Based on the investigation of some typical plantation forests and peripheral natural grasslands in a droughtprone semihumid area on the Loess Plateau, the analyses on meteorological conditions and the trial of shallow scarification of plantation land with fallen seeds and seedlings for regeneration were mainly regarded the factors affecting the natural regeneration of plantation forests. The results indicated that the germination of fallen seeds on land surface and seedling formation would be the key links for the natural regeneration of plantation forests under drought, in which water factor might be a dominant factor. Closely related to rainfall, the favorable aspects to ensure seedling occurrence for regeneration is snow cover accumulated in winter without thawing until early spring, and also precipitation lasting for a number of days or continuous rainy overcast appearing in spring or droughty season. Owing to successive scarcity of precipitation in winter and spring, it is difficult to emerge seedlings for regeneration in dry land. Nevertheless, to earth up may improve soil moisture conditions in dry land for fallen seeds and overcome the restriction of precipitation scarcity, thus the emergence of seedlings for regeneration may be improved. In order to stabilize the survival and growth of seedlings and achieve the natural regeneration of plantation forests, it is suggested to take some artificial measures. References | Related Articles | Metrics

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Experiment on Cultivation of Cistanche deserticola  under Drip Irrigated in the Hinterland of the Taklimakan Desert LI Bing-Wen, QIU Yong-Zhi, ZHOU Hong-Wei, XU Xin-Wen, WANG Qiang, FAN Jing-Long, JIN Zheng-Zhong, CHANG Qing, XU Bo, ZHANG Zhong-Liang 2012, 29 (5):  751-756.  Abstract ( 1599 )   PDF (1644KB) ( 1165 )   Cistanche deserticola is an endangered wild species adapting to growing in arid or semiarid area. This species is traditionally used in many countries as a tonic, and it has been currently planted as a new cultivated plant species in northwest China. In order to improve the cultivation technical level of C. deserticola,many cultivation experiments under drip irrigation with saline water were carried out in the hinterland of the Taklimakan Desert, including the different ditch and seeding ways, different inoculation depths and technology of stably increasing yield. The results of this study are as follows:(1) It is an effective way of improving the inoculation rate to increase the contacting rate of C. deserticola seeds with the hostplant roots, and the harvested biomass of C. deserticola under different cultivation ways was in orders of ditching seeding >holing seeding >digging seeding, and broad seeding >line seeding with seeding paperboard;(2) The harvested biomass of C. deserticola was increased with the increase of seeding amount under ditching seeding and broad seeding, but there was a upper limit, and the suitable seeding amount is 300 seeds/m under drip irrigation in sand;(3) Considering the cultivation ways and their cost, the inoculation depth should be kept in the main areas of the hostplant roots, and the depth should be shallower than 60 cm under drip irrigation in sand;(4) Once C. deserticola was inoculated, it could be harvested repeatedly. However, the harvested biomass of C. deserticola differed remarkably from different years, and the first three years were the main harvest time. The harvested biomass of C. deserticola could keep over 1 plant/m, and the economic income of cultivated C. deserticola was very remarkable since its fresh yield was as high as 1 800 kg/hm2 in average. References | Related Articles | Metrics

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Spatial Distribution of Fine Roots of Juglans regia Trees in Walnut-wheat Intercropping System in Arid Oasis WANG Shi-Wei, PAN Cun-De 2012, 29 (5):  757-762.  Abstract ( 1829 )   PDF (1105KB) ( 926 )   Under irrigation in an oasis in the Tarim Basin, the plant mode of Juglans regia L. intercropped with crops was used more because of the limited area of cultivated land per capita. The research was conducted to investigate the spatial distribution of fine roots (diameter ≤1 mm) of J. regia trees in J. regia wheat intercropping system in the Tarim Basin using the layered digging and image analysis methods. Results showed that, in vertical direction, the fine root length density of J. regia trees increased with the increase of soil depth in layer of 0-40 cm and decreased with the increase of soil depth below 40 cm. The fine roots grew mainly in soil layer of 10-80 cm, their proportion accounted for 65.9% of the total, and that in soil layer below 80 cm was 34.1%. The fine root length density of J. regia trees in the J. regia wheat intercropping system varied with soil depth in an exponential way. In horizontal direction, the proportion of the fine roots 175 cm away from the tree rows was 65.3% of the total. The fine root length density in the middle of alley in the intercropping system was minimum and relatively even. The patterns gained by analyzing the vertical and horizontal distribution of fine roots showed that, under irrigation in the oasis, the soil layer of 10-60 cm within 175 cm away from the trees was the main area for J. regia trees and wheat to compete soil moisture and fertilizer. Thus it is necessary to strengthen the water-fertilizer management in this competition area in farming practice. References | Related Articles | Metrics

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Clonal Configuration and Ramet Population Characteristics of Stipagrostis pennata in Different Habitats ZHU Li-Jie, WANG Shao-Ming, XIA Jun, ZHU Hong-Wei 2012, 29 (5):  770-775.  Abstract ( 1844 )   PDF (1753KB) ( 1018 )   This paper researched the morphological plasticity of clonal plant ramets at individual and population level, clonal configuration and ramet population characteristics of Stipagrostis pennata in different habitats (different slope positions, associated with different plant communities, different mobile dunes) in the Gurbantunggut Desert, Junggar Basin, Xinjiang. The average height of ramets, internode length, number of tillers, root diameter, underground rhizomes, average length of underground rhizomes of S. pennata were measured and analyzed, and the parameters of clonal configuration and the ramet  population characteristics of S. pennata in different habitats were studied. The results showed that the strength of ramets of S. pennata was high, the branches were more, and the spacer among ramets (internode length) was highly reduced, so S. pennata was in a typical “intensive” clonal growth pattern. Moreover, after compared the ramet population characteristics of S. pennata at different slope positions of semi-fixed sand dunes, it was revealed that the number of tillers and the average rhizome length of S. pennata at the dune top were significantly higher than those at the dune bottom. After analyzing the ramet population characteristics of S. pennata associated with different plant communities, it was revealed that the branches of S. pennata associated with Lappula myosotis community were obviously more than those associated with Seriphidium terraealbae, the branching density was higher, and the average rhizome length was shorter. Compared with semi-fixed dune, S. pennata growing at fixed dune had significantly the larger numbers of tillers and rhizomes, longer root diameter and higher aboveground biomass and underground rhizome biomass. The ramet population characteristics of S. pennata in different habitats were discussed based on the integration of clonal plants at the aspects of resources utilization and phenotypic plasticity. References | Related Articles | Metrics

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Study on Vegetation Distribution and Species Diversity in the Ebinur Lake Basin MA Yu-E, QIAN Yi-Bing, DUAN Shi-Min, CHANG Yi-Shen, LI Yang-Qi 2012, 29 (5):  776-783.  Abstract ( 1556 )   PDF (1509KB) ( 1115 )   In this study, the species composition and structural characteristics of the plant communities along the south and north transects in the Ebinur Lake Basin were systemically observed and measured. Based on the results, the important values of the species were chosen to calculate the indices of species diversity, evenness and dominance, and analyze the vegetation distribution and species diversity. The results are as follows: (1) Plants in the study region can be divided into ten communities, among them the Form.Tamarix chinensis was widely distributed; (2) There was a zonal distribution of vegetation in the lake basin. The species diversity of plant communities varied with the change of terrain, and the species diversity and evenness of the plant communities were high in the places with high altitude; (3) Along the south and north transects, soil salt content was the main factor affecting plant growth. With the increase of soil salt content, the number of species tended to decreasing and the structure of plant communities to simplifying. Species diversity increased with the decrease of soil salt content, showing a high species diversity of plant communities on the alluvialproluvial plain where the south transect was located in and the desert zone where the north transect was located in; (4) Affected by wind regime and soil salt content, the vegetation composition along the south transect was quite different from that along the north one. In the lakeshore, the species diversity of plant communities was higher and the plant growth was more flourishing along the south transect than that along the north transect.   References | Related Articles | Metrics

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Photosynthetic Capacity of Malus sieversii Trees in Natural Forest MAO Pei-Li, ZANG Run-Guo, BAI Zhi-Qiang, XU Zheng, GUO Zhong-Jun, LIU Duan 2012, 29 (5):  784-790.  Abstract ( 1928 )   PDF (1717KB) ( 924 )   Photosynthesis is a basic eco-physiological process for the functioning of ecosystems. Malus sieversii(Ledeb.) Roem. is the most important dominant species in the wild fruit forest on the northern slope of the Tianshan Mountains in northwest China. M. sieversi population has been declining rapidly due to more and more intensive anthropogenic disturbances. Research on the photosynthetic characteristics of M. sieversii of different size classes is critical to understand the functions of its dominated ecosystems and to take proper measures to conserve this endangered species. Net assimilation rate (A), stomotal conductance (gs)and specific leaf area (SLA) of sun-facing M. sieversii leaves at upper and lower parts of 64 adult trees were measured in a natural wild fruit forest in Xinyuan County on the northern slope of the Tianshan Mountains in Xinjiang, northwest China. The results showed that there was a significant effect of stem diameter class on photosynthetic characteristics of M. sieversii. Both Aarea and Amass were increased with the increase of diameter class, whereas gs was increased at first and then decreased, and the maximum values appeared at the main stem diameter of 25-35 cm at 0.5 m height. There was a significant effect of leaf position on photosynthetic characteristics. Aarea, Amass and gs of the leaves on the upper part of branches were significantly higher than those on the lower part. The results of regression analysis revealed that Aarea and gs were increased in a quadratic polynomial way with the increase of stem diameter, whereas Amass was increased in a linear relation. With the increase of diameter class, the change of SLA was not significant. There was a significant effect of leaf position on SLA. SLA of the leaves on the upper part of crown was significantly lower than that on lower part, and the differences of Amass between the leaves on the upper and lower parts was low. Aarea of the leaves on both upper and lower parts was increased with the increase of gs, but the regression equations were different. Aarea of upper leaves was increased in a power function with the increase of gs, where as Aarea of lower leaves was increased in a quadratic polynomial way with the increase of gs.  References | Related Articles | Metrics

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Analysis on Habitat and Amino Acid Content of Cordyceps sinensis YU Bin, FENG Feng-Ying, LIANG Liu-Ke, ZHU Lian-Qi, ZHAO Wen-Liang 2012, 29 (5):  791-796.  Abstract ( 1625 )   PDF (1839KB) ( 1088 )   Cordyceps sinensis is an endemic species of entomophagous fungus distributed in the alpine regions of the Qinghai-Tibet Plateau. It has been long known by its synonym C. sinensis both in scientific and non-scientific communities. C. sinensis, a unique entomophagous fungus parasitizing the larvae of the genus Thitarodes, is mainly distributed in the alpine meadows of the Qinghai-Tibet Plateau, and known as a valuable invigorant in traditional Chinese medicine for centuries in China. In order to research the properties of C. sinensis, some samples were collected from Qinghai Province, the contents of amino acids and elements were measured in laboratory, and the results were compared with those of other samples collected from Sichuan and Yunnan provinces and Tibet Autonomous Region. The conclusions show that the contents of amino acids are ample in C. sinensis, and the level of contents is clearly visible from basal caterpillar to stroma. Compared with the samples collected from Yunnan, Sichuan and Tibet, the contents of amino acids in C. sinensis samples collected from Qinghai Province were in average level. In addition, there were abundant mineral elements in C. sinensis. References | Related Articles | Metrics

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Effect of Super Absorbent Polymer on Seed Germination and Seedling Roots of Haloxylon ammodendron and H. persicum LI Xing, JIANG Jin, SONG Chun-Wu, WEI Zhen-Jiang, YIN Wen-Juan 2012, 29 (5):  797-801.  Abstract ( 2067 )   PDF (1270KB) ( 941 )   Effect of super absorbent polymer (SAP) on the seed germination and seedling root morphology of Haloxylon ammodendron and H. persicum  was investigated based on a pot experiment. The results showed that, compared with the contrast, the seed germination rates of H. ammodendron and H. persicum were increased by 18.7% and 24.0% respectively when SAP concentration was 0.05%. Vertical growth of seedling roots of H. ammodendron  was inhibited, while the growth and biomass accumulation of lateral roots were promoted when SAP concentration was 0.05%. Root length, lateral root number and root biomass of H. persicum all reached their maximum values at 0.1% SAP concentration. Seed germination and seedling root growth were all inhibited when SAP concentration was 0.2%. It was concluded that the perfect SAP concentration for H. ammodendron growth was 0.05%,and the best effect of SAP concentration for H. persicum varied in a range of 0.05%-0.1%. References | Related Articles | Metrics

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Effect of Water Stress on Root Vigor and Leaf Physiology of Cotton under Mulch Drip Irrigation YANG Chuan-Jie, LUO Yi, SUN Lin, GAN Rong, JI Li-Li-·A-Bu-Du-Wai-Li, ZHANG Yan 2012, 29 (5):  802-810.  Abstract ( 1822 )   PDF (5489KB) ( 1126 )   Water stress is one of the most important abiotic stresses. A field experiment was conducted to evaluate the growth and physiological response of cotton plants to soil moisture stress under mulch drip irrigation. The total irrigation volumes of 5 400, 4 950, 4 500, 3 750, 2 850 and 2 550 m3/hm2 were designed for each treatment according to the upper irrigation limits of 105%, 100%, 95%, 90%, 85% and 80% of field capacity, respectively. Differences in root vigor, chlorophyll, proline and malondialdehyde (MDA) contents were tested at cotton florescence and boll stage so as to reveal the physiological response of cotton plants to soil moisture stress. The relationships between soil moisture content and the praline and MDA contents as well as root vigor were analyzed. The results showed that the biomasses of dry shoots and leaves, leaf area, plant height, chlorophyll content and root vigor were significantly decreased due to water deficiency, while the rootshoot ratio, proline and MDA contents were sharply increased. The results also revealed that there was a negative correlation between soil moisture content and the proline and MDA contents, their correlation coefficients were -0.704 and -0.667 respectively, but the root vigor was decreased with the decrease of irrigation volume, their correlation was positive, and their correlation coefficient was 0.67. Moreover, this study revealed that the threshold level for water supply was 4 500 m3/hm2 to keep crop away from water stress. These results also revealed that the proline content, root vigor and MDA content were sensitive to soil moisture content. References | Related Articles | Metrics

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Study on Molecular Systematics of Genus Lappula Moench in China HUANG Jian-Feng, ZHANG Ming-Li 2012, 29 (5):  811-815.  Abstract ( 2470 )   PDF (907KB) ( 1180 )   In this paper, the molecular phylogeny of the sequences of nrDNA ITS and rpS16 regions of 13 species representing Lappula Moench was studied by taking Arnebia guttata and Coldenia procumbens as the outgroups and by using PAUP* 4.0. Consistent phylogenetic trees were obtained with the maximum likelihood and the maximum parsimony methods based on DNA sequence datasets. The topologies of gene trees revealed that the Lappula was monophyly, and the previous studies failed to avoid the subjectivity in the taxonomic categories and identified characters of the genus, making it unable to reflect the actual phylogenetic relationships of Lappula. Combining with morphology characteristics, this study concluded that the corollas of Lappula evolved from small form to large form, fruits from homotype to heterotype, and nutlet fringes from tuberculate or prickly one to winged one.   References | Related Articles | Metrics

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Response of Nostoc sp. to UV-B Radiation and the Protective Effect of Exogenous Antioxidants to Nostoc sp. DENG Song-Qiang, YANG Cui-Kun, AN Xiao-Liang, HU Chao-Zhen, CHEN Lan-Zhou 2012, 29 (5):  816-819.  Abstract ( 1632 )   PDF (634KB) ( 917 )   In this paper, the effects of UV-B radiation on the physiological and biochemical processes of [WTBX]Nostoc[WTBZ] sp., one of cyanobacteria isolated from desert algal crust, were investigated, and the protective effects of ascorbic acid and N-acetyl-L-cysteine were researched. The results show that the PSII activity [WTBX](Fv/Fm)[WTBZ] of stressed cells was significantly decreased with the increase of irradiance time and intensity, the chlorophyll fluorescence transits and photosynthetic parameters （ET0/ABS、ET0/TR0 and RC/CS0）] were also decreased significantly, but the ROS generation was increased. Exogenous 0.5 mM ascorbic acid or N-acetyl-L-cysteine could significantly decrease the production of ROS (reactive oxygen evolution), and the protective effect of ascorbic acid was better than that of N-acetyl-L-cysteine. The results suggested that Nostoc sp. adapted to the detrimental UV environment in desert, and exogenous antioxidant could effectively protect cells from UV-B damage. References | Related Articles | Metrics

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Analysis and Assessment on Solar Energy Resourcesin Altay Prefecture, Xinjiang WANG Jian-Gang, WANG Sheng-Tao, XU Jian-Chun, PAN Dong-Mei, LIANG Xiao-Zhong 2012, 29 (5):  820-825.  Abstract ( 2090 )   PDF (1628KB) ( 1305 )   Altay Prefecture in Xinjiang, west China, is of arid climate. Though its latitudes are a little northern, its solar energy is abundant because of long sunshine duration. Based on the theoretical calculation and analysis, in this paper a linear empirical equation of astronomical solar radiation was developed, and it was reckoned according to the latitudes. The computer software developed is convenient for calculation. The practical values and precision of solar radiation in Altay Prefecture were confirmed, and the distribution of astronomical solar radiation and ground total solar radiation was comprehensively analyzed and assessed. According to the calculated results, the annual total solar radiation energy in the Ertix River and Ulungur River basins varied from 5 400 MJ·m-2 to 5 700 MJ·m-2. Since 1960, the total solar radiation had been in a decrease trend with a decrease rate of -4.836 2 MJ·m-2·（10 a）-1, but it has begun to increase from 1999. The desert area between 45° N and 46° N is characterized by seldom precipitation, low latitudes and high solar radiation, so the solar radiation may be as high as 5 900MJ·m-2, and the potential solar radiation resources are very high. References | Related Articles | Metrics

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Study on Climate Change in Urumqi and Its Relationship with EI Nino/La Nina Events in Recent 49 Years XI Xiu-Mei, ZHAO Jing-Bo 2012, 29 (5):  826-831.  Abstract ( 1969 )   PDF (2383KB) ( 1350 )   In this paper, the methods of trend line and statistical analysis were employed to analyze climate change in Urumqi, Xinjiang and its relationship with the EI Nino/La Nina events based on the data of monthly temperature, precipitation and wind speed at Urumqi Meteorological Station and the statistical results of the EI Nino/La Nina events during the period of 1961-2009. Results indicated that both temperature and precipitation were increased, and wind speed was slightly decreased in recent 49 years. Climate changed towards a warmingwetting pattern. The statistical results showed that 16 EI Nino events and 13 La Nina events occurred during the period of 1961-2009. EI Nino/La Nina events affected seasonal precipitation, annual average temperature and wind speed in Urumqi. In El Nino years, winter precipitation in Urumqi was less than that in normal years, wind speed was slightly lower, and the average temperature was slightly higher. It was easy to occur warm winter and drought in Urumqi in the El Nino years. Spring and summer precipitation and wind speed were high in Urumqi in the La Nina years, and it was easy to occur flood, cold wave and wind disasters during the La Nina events. References | Related Articles | Metrics

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Analysis on Applicability of NCEP/NCAR in Reanalyzing Temperature in the Aksu River MU Zhen-Xia, XIE Lei, JIANG Hui-Fang 2012, 29 (5):  832-837.  Abstract ( 1683 )   PDF (1478KB) ( 928 )   In order to properly guide the studies on climate change and find out the reliable data sources, this paper discussed the applicability of NCEP/NCAR in reanalyzing temperature in the Aksu River.The monthly temperature data observed by 6 meteorological stations in the Aksu River Basin during the period from 1960 to 2007 and Kriging method were used. The results revealed that there was a good correlation between the analyzed temperature values with NCEP/NCAR and the observed ones at the meteorological stations, and the maximum correlation coefficient was 0.845. It was found that the NCEP/NCAR reanalysis was able to be used to derive the values of annual, seasonal and monthly temperature in the study area. Compared with the temperature values observed by the meteorological stations, the analyzed values with NCEP/NCAR reanalysis was lower than the observed ones. There was a similar trend of temperature change between the reanalyzed values with NCEP/NCAR and the observed data. Except some months, the reanalyzed values of monthly temperature with NCEP/NCAR were generally lower than the observed data, especially in spring, and there was a good correlation between the analyzed and observed data of temperature in autumn. References | Related Articles | Metrics

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Analysis on Spatiotemporal Change of Dry-wet Conditions in the Heihe River Basin during the Period from 1960 to 2008 ZHANG Ya-Ning, ZHANG Bo, ZHUO Ma-Lan-Cao, WANG Qiang, ZHAO Yi-Fei 2012, 29 (5):  838-846.  Abstract ( 1690 )   PDF (3413KB) ( 1172 )   In recent 50 years, a significant climate warming has occurred in China under global climate change, and it has facilitated the development of drought. Climatic drywet conditions have attracted more and more attention in recent years. The change of drywet conditions will cause the farreaching impacts to prospective agricultural production and natural environment, especially in northwest China. Located in the arid and semiarid areas in northwest China, the Heihe River Basin is the second largest inland river basin in China. Water resources have become as a “bottleneck” of social and economic development and ecological regeneration in the Heihe River Basin. Investigation on the temporal and spatial distribution of water resources in this region would be greatly helpful for the utilization efficiency improvement, appropriate redistribution of water resources, and relieving environmental deterioration. Based on the daily meteorological data observed by 16 meteorological stations in the Heihe River Basin during the period from 1960 to 2008, in this study the values of daily evapotranspiration of reference crop were calculated using the PenmanMonteith method recommended by the FAO, and then the values of monthly, seasonal and annual evapotranspiration of reference crop were obtained. In order to study the temporal and spatial change of drywet conditions in the study area, the humid index values at different time were interpolated using the data of evapotranspiration of reference crop and precipitation. By using the method of Inverse Distance Weighted (IDW) under ArcGIS, the spatial change of the drywet conditions was lucubrated so as to research the regional difference. In this study, a preliminary analysis on the main factors affecting the change of the drywet conditions was also carried out. The results indicated that the values of mean annual humid index were generally in an increase trend in a fluctuation way in the Heihe River Basin and its upper, middle, lower reaches in recent 49 years, and the surface humid status was improved to some extent. It was also found that the fluctuation of annual humid index was obvious, and the Cv (coefficient of variation) values of humid index in the Heihe River Basin and its upper, middle, lower reaches were 14.97%, 13.63%, 25.47% and 37.72% respectively. Seasonally, the drying trend occurred in spring, and the wetting trend occurred in summer, autumn and winter. According to the humid index, summer was the wettest season, then autumn and spring, and winter was the driest season. Apart from the lower reaches, the variation rate of summer humid index was the fastest, so the change of the drywet conditions was the most unstable in summer, and it was the most stable in winter. Correlation analysis between humid index and meteorological variables indicated that the change of precipitation was the dominant cause affecting the change of drywet conditions in the Heihe River Basin, and the change of other climate factors can enhance or weaken the change of drywet conditions. References | Related Articles | Metrics

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Analysis on the Change of Precipitation in the Qilian Mountains CHEN Zhi-Kun, ZHANG Shu-Yu, LUO Jia-Li, LI Zhao-Rong, SUN Yan 2012, 29 (5):  847-853.  Abstract ( 2004 )   PDF (2314KB) ( 1151 )   In this paper, the various trends and distributional characteristics of precipitation in the Qilian Mountains were studied using the data of hourly and daily precipitation in the mountains. Moreover, the tree-ring data of Picea asperata growing in the study area were used to analyze the response of tree-ring width to precipitation in the mountainous. A unitary linear regression model was used to develop a transfer equation so as to reveal the relationships between the standardized chronology of tree-ring width and the average precipitation at Minle Meteorological Station during the period from August to next July and the change of annual precipitation in recent 200 years. The results show that precipitation in 19th century was higher than that in 20th century. Drought occurred increasingly in 20th century, especially severe drought occurred in the 1920s and 1930s, such trend was consistent with that in north China. Precipitation in the Qilian Mountains was closely related to the altitude, and most precipitation occurred in the afternoon and nighttime. Flood season in the study area is in July and August. Moreover, the frequency of extreme precipitation was increased in recent decades, and the change of annual precipitation was not significant. References | Related Articles | Metrics

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Analysis on Precipitation in Huangnan Qinghai Province in Recent 50 Years LI Yan-Lin, XU Cun-Ping, XU Xian-Hua, LIU Cai-Hong 2012, 29 (5):  854-861.  Abstract ( 1867 )   PDF (2940KB) ( 785 )   In this paper, the variation of annual precipitation in Huangnan Prefecture was analyzed based on the precipitation data observed by 4 meteorological stations in the prefecture during the period from 1961 to 2010 by using the method of climatological diagnosis. The results show that there was a big difference in mean annual precipitation among the meteorological stations, and the annual precipitation was gradually decreased from the south to the north. The coefficient of variation revealed that there was an increase trend of annual precipitation from the south to the north, and the annual precipitation at all the stations was in a normal distribution. Except at Zeku, there was a decreased trend of annual precipitation in Huangnan Prefecture during the period of 1961-2010, but this trend was not significant. The variation of seasonal precipitation was different from different meteorological stations, but winter precipitation was in an increase trend at all the stations, especially in the south. Analyzed results revealed that a sharp reduction of annual precipitation occurred in the Henan region in 1985, and it occurred possibly around the early 1990s at Jianzha, Tongren, and Zeku meteorological stations. The results also revealed that there was a 10-year periodic change of annual precipitation at these 4 meteorological stations, and 2-4-year, 2-year, 3-5-year and 3-5-year one at Jianzha, Tongren, Zeku, and Henan meteorological stations respectively. References | Related Articles | Metrics

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Analysis on Cloud and Vapor Flux in the Northeast of the Qinghai-Tibet  Plateau during the Period from 2001 to 2011 DU Liang-Liang, LI Jiang-Ping, CHEN Xiao-Yan, SHANG Ke-Zheng, YANG De-Bao, WANG Shi-Gong 2012, 29 (5):  862-869.  Abstract ( 1485 )   PDF (2459KB) ( 1178 )   The northeast of the Qinghai-Tibet Plateau is the intersection transitional zone of the Qinghai-Tibet Plateau and the Loess Plateau, also the transitional zone of agriculture and animal husbandry, the terrain is complex, and it is often affected by various weather systems, so the response of climate change is very sensitive. It is characterized by the fragile ecological environment, soil erosion and water loss, pasture degeneration, land desertification and various environmental problems. Therefore, it is very meaningful for further understanding the climatic characteristics and climate change in the Qinghai-Tibet Plateau by analyzing the climate change and its trends in the northeast of the plateau. However, the recent discussion about cloud cover and its related factors in the northwest or in the whole plateau was insufficient. So it is necessary to study the temporal change of cloud cover and more detailed weather characteristics related to cloud cover over the northeast of the Qinghai-Tibet Plateau. It is of great significance for implementing artificial precipitation and developing air resources. Based on the daily cloud cover data observed by 22 meteorological stations and the NCAR/NCEP reanalysis data in the northeast of the Qinghai-Tibet Plateau (32°-37° N, 99°-104° E) during the period from 2001 to 2011, the development characteristics of cloud cover and the relationship between cloud cover and vapor flux in the northeast of the Qinghai-Tibet Plateau in recent 10 years were studied in terms of the statistical analysis and the HYSPLIT_4 Model. The results showed that the total cloud cover and the low cloud cover over the study area was decreased from the south to the north. There was an increase trend of total cloud cover and low cloud cover over the study area during the period from 2001 to 2011, especially in spring and summer. When rain or snow occurred, appear probability of cirrus was the highest, then that of altostratus, and that of cumulus was the lowest. Appear probability of convective cloud was higher than that of nonconvective cloud over the northeast of the Qinghai-Tibet Plateau. Water vapor is one of the main factors affecting the distribution of precipitation and the change of convective cloud. Water vapor flux came mainly from 700 hPa layer, and water vapor flux could reflect the low cloud cover well. References | Related Articles | Metrics

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Characteristics of Soil Enzyme Activities in Different Grasslands in the Western Slope of the Helan Mountain, China QIN Yan, NIU De-Cao, KANG Jian, CAO Ge-Tu, ZHANG Si-Lian, FU Hua 2012, 29 (5):  870-877.  Abstract ( 2095 )   PDF (1941KB) ( 1237 )   Soil enzymes are the specific biological catalysts for biochemical reaction in soil, and one of the indicators of evaluating soil health. This study was conducted at the grasslands in the western slope of the Helan Mountain and its piedmont in Alxa, Inner Mongolia, China. With measuring the distribution characteristics of soil enzyme activities, the relationships between soil enzyme activities and soil, vegetation and climatic factors were studied. The results are as follows: (1) Soil enzyme activities were decreased with the decrease of altitude and in an order of alpine meadow > mountain steppe > mountain desert steppe > steppe desert, and the difference was significant in topsoil (0-10 cm in depth); (2) Soil enzyme activities were decreased with the increase of soil depth; (3) According to the partial correlation and stepwise regression analysis, the main factors affecting the activities of soil urease and saccharase were soil microbial biomass carbon, soil organic carbon and total nitrogen, soil alkaline phosphatase activity was mainly affected by soil microbial biomass carbon and total nitrogen, and soil catalase activity was mainly affected by soil microbial biomass, total nitrogen, pH value and precipitation. References | Related Articles | Metrics

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Mobility of Heavy Metals and the Leaching Characteristics with Ascorbic Acid from Urban Soil in Tongchuan City LI Xiao-Ping, NAN Xiao-Juan , HOU Kang, CHEN Cong 2012, 29 (5):  878-882.  Abstract ( 1493 )   PDF (846KB) ( 1007 )   In this paper, the mobility of heavy metals Pb, Cu, Cr and Zn in urban soil in Tongchuan City and the leaching characteristics with ascorbic acid were investigated with once balance method. The pollution degree was assessed with the ecological risks index. The results showed that the contents of heavy metals Pb, Cu, Cr and Zn in urban topsoil were significantly different, and the contents of Pb and Cu were high. The holistic pollution degree of heavy metals was serious. The speciations of these 4 heavy metals were dominated by the residual forms, and Zn and Cu was mobile in soil environment. However, Pb was not mobile due to its existence forms of hydroxide, carbonate or phosphatic in the environment. The total potential ecological risk degree was high. It was found that Pb was a main element of potential ecological risk, Cr, however, was easy to be leached and transferred in soil organism, which could be paid more attention to in the future. References | Related Articles | Metrics

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Vertical Distribution of Soil Organic Carbon Content in Rhizosphere of Jujube at Its Different Growth Stages under Drip Irrigation with Salty Water WANG Cheng, LI Ning, WANG Xing-Peng, ZHANG Jun, JIANG Qian, WANG Liang 2012, 29 (5):  883-889.  Abstract ( 1634 )   PDF (2536KB) ( 897 )   In this paper, the effect of drip irrigation with salty water on soil organic carbon content in rhizosphere of jujube at its different growth stages was explored based on the experiment of field drip irrigation with salty water under different irrigation quotas and different salinity levels of irrigation water. The results showed that the soil organic carbon content varied with soil depth, salinity level of irrigation water and irrigation quotas, and its curve was Sshaped. The salinity affecting soil organic carbon content was in an order of 3 g/L>4 g/L>freshwater>2 g/L, organic carbon content in topsoil 10-30 cm in depth was higher than that in soil layer of 30-50 cm, but the organic carbon content in soil layer of 30-40 cm was relatively low. When the salinity of irrigation water was constant, the effect of irrigating quota on soil organic carbon content was in an order of 30 L>20 L>10 L, which indicated that an appropriate increase of irrigating quota was an effective way of soil desalination when jujube was irrigated with salty water. Compared with other treatments, drip irrigating quota of 30 L and 2 g/L salinity of irrigation salty water could significantly promote the utilization of soil organic carbon in rhizosphere of jujube. References | Related Articles | Metrics

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Experimental Study on Simultaneous Observation of Snowmelt and Soil Moisture Content under Air Temperature Increase GUO Ling-Peng, LI Lan-Hai, XU Jun-Rong, BAI Lei, LI Xue-Mei 2012, 29 (5):  890-897.  Abstract ( 2198 )   PDF (1570KB) ( 1537 )   Climate change plays an important role in dynamic changes of snow cover and soil moisture content. A warming weather in last decades had resulted in the shortening of snow cover season, reduction of water storage in snowpack and earlier snowmelt in spring, and these affected the spatiotemporal distribution of soil moisture content. In this study, a temperature increase experiment was performed at the Tianshan Station for Snow Cover and Avalanche Research during snowmelt season with a temperature increase system based on the principle of TFACE. The field experiment was conducted under three treatments: natural status, temperature increase treatment Ⅰ (air temperature was increased by about 2 ℃) and temperature increase treatment Ⅱ (air temperature was increased by about 4 ℃). The results indicated that snowmelt rate was significantly increased under both cases of temperature increase and more dust adhering to snow surface due to strong air convection caused by local warmer air. Snow cover disappeared 19 and 25 days earlier under the treatment Ⅰ and treatment Ⅱ than that under nature conditions, respectively. Corresponding to the change of snow cover status, soil moisture content was increased in varying degrees at different soil depth. Maximum soil moisture content occurred 13 and 22 days earlier, which revealed that stream flow peak might come earlier under climate change in the future in the watersheds where snowmelt water is an important water source. The field experiment provided an evidence to prove that global warming will bring a farreaching effect on the spatiotemporal distribution of regional water resources.   References | Related Articles | Metrics

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The Sources and Hydrochemical Properties of Groundwater in the Liyuan River Basin, Gansu Province ZHANG Qing-Huan, QI Shi, MA Jin-Zhu 2012, 29 (5):  898-906.  Abstract ( 1697 )   PDF (2184KB) ( 1024 )   The Liyuan River Basin is located in an arid inland in northwest China and it is an important agricultural area in the Hexi Corridor, Gansu Province. As a tributary stream of the Heihe River, the Liyuan River is of significance in promoting economic and ecological development in the Zhangye Basin. The ecosystem in the region is highly vulnerable and strongly affected by the hydrochemical composition of water. For this reason, it is necessary to monitor the hydrochemical evolution in this area so as to avoid the degeneration of the local ecological environment. As surface water resources are limited, groundwater has gradually become as an indispensable water source in people’s daily life and agriculture. A lack of understanding of the mechanisms of groundwater evolution may lead to unwise utilization of groundwater, and thus have a negative impact on local sustainable development may be resulted in. In this paper, the relationships between hydrochemical properties and stable isotopes were analyzed. The transformation of surface water and groundwater was lucubrated so as to provide the government with decisional support concerning groundwater conservation. It was assumed that groundwater flowed in the same path from the southwest to the northeast based on considering the flow direction of the Liyuan River. The results showed that the TDS values of groundwater increased from the southwest to the northeast. The highest TDS value was 1 258 mg/L, which was too high for drinking use; this was the result of water-rock interaction and the salinization caused by the infiltration of irrigation water. Along with the flow path, the hydrochemical type of deep groundwater changed from Ca-HCO3 to Ca-Mg-HCO3, Mg-SO4 and Na-SO4, that of shallow groundwater changed from Ca-HCO3 to Mg-HCO3-SO4 and Mg-SO4, and that of surface water remained as Ca-HCO3 without change. Among the hyrdochemical changes, the increasing content of Na+ was the most apparent. There were two reasons for the increase of Na+ content along the flow path: the first was that Ca2+ in groundwater exchanged with Na+ in minerals in the cationexchange process, and the second was the weathering of silicate minerals that produced Na+. The results simulated with Phreeqc software identified that there were the main water-rock interactions in groundwater along the flow path. In deep groundwater, calcite was precipitated at first, and then dissolved; whereas CO2 gas, gypsum, dolomite and halite were dissolved. In shallow groundwater, calcite was dissolved at first, and then precipitated, while gypsum and halite were dissolved. The modeling results were the evidences of the hydrochemical processes. The tracer elements of 2H and 18O in water molecules were used in this paper to analyze the water resources and recharge patterns. By comparing the δ18O-δ2H relation line of surface water and groundwater, global meteoric water line (GMWL) and local meteoric water line (LMWL), it was concluded that groundwater was recharged by precipitation or snowmelt water via surface runoff from the mountain area. Deep groundwater migrated upward to recharge shallow groundwater and surface water. References | Related Articles | Metrics

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Primary Study on the Rational Time of Ecological Water Conveyance to Lower Reaches of the Tarim River YE Mao, XU Hai-Liang, REN Ming 2012, 29 (5):  907-912.  Abstract ( 2031 )   PDF (1599KB) ( 1063 )   In this paper, the time and volume of 8 times of ecological water conveyance to lower reaches of the Tarim River was analyzed based on the data of ecological water conveyance and the field investigation on natural vegetation. The change of water volume from the Bosten Lake and the Tarim River to the lower reaches was summarized. The correlation between the seed falling time of 32 plants species and the watering time of the river course in the lower reaches of the Tarim River was analyzed, and the beginning time of ecological water conveyance was discussed. Furthermore, the feasible and rational beginning time of ecological water conveyance was put forward for conserving and regenerating natural vegetation in the study area. The results are as follows: (1) Because of the serious water consumption along the river channel, conveyed water for the ecology is mainly relied on stream flow of the Tarim River instead of the Bosten Lake. So it is a precondition that whether water resources in the mainstream area of the Tarim River are enough or not; (2) The 8 times of ecological water conveyance were mainly implemented during the periods from April to June and from August to October, because 49.73% water flows into the Bosten Lake and 82.33% water flows into the Tarim River during these periods; (3) The correlation between the watering time of the river course and the regeneration of natural vegetation was low, because the seed falling time of natural vegetation was not considered previously. Therefore, it is more rational to convey water from the Tarim River than from the Bosten Lake; (4) Judged from the seed falling time, the period from July to September is the most rational, however, that from midAugust to the end of September is the most reasonable if judged from stream flow of the Tarim River. References | Related Articles | Metrics

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Development Status and Prospect of Standardized Desertification Combating in China CUI Xiang-Hui, LU Qi 2012, 29 (5):  913-919.  Abstract ( 1578 )   PDF (775KB) ( 1460 )   Standardization is the groundwork of forestry development and ecological and environmental conservation, and it is also the main guarantee of carrying out successfully desertification combating. In this paper, the development status at home and abroad and the existing problems in the standardization of desertification combating in China were analyzed. It is considered that the existing problems are as follows: (1) The standard documents were not enough, and the structure was unreasonable; (2) The standardization level and degree of technological and scientific research achievements should be significantly improved; (3) The standard system was not perfect; (4) The participation consciousness in international standardization activities was insufficient. In the background of ecological and environmental degeneration, the area of desertification land is still likely to in continuous expansion. Moreover, the whole requirements of standardized desertification combating were expounded, and the development overall goal, emphases and some key standard documents should be formulated in the near future. It is pointed out that the development direction and some emphases are the organization construction, standardization personnel training, standard system construction and international standard participation. References | Related Articles | Metrics

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Analysis on Depositional Features of the Late Holocene Paleo-flood Slackwater Deposit in Middle Reaches of the Weihe River ZHAO Mei, CHA Xiao-Chun, HUANG Chun-Chang, PANG Jiang-Li, YANG Ling 2012, 29 (5):  920-925.  Abstract ( 1738 )   PDF (1647KB) ( 1269 )   Based on the field investigation, a Holocene paleo-flood slackwater deposit (SWD) in a Holocene loesspaleosol profile was found in middle reaches of the Weihe River Basin. The grain size, magnetic susceptibility, CaCO3, loss-on-ignition and surface micro-structure of quartz grains were analyzed in laboratory. The results showed that the properties of SWD were different from those of loess and paleosol. This SWD is identified as the most typical Holocene paleoflood deposit. According to the OSL dating and stratigraphy comparison, the age of the SWD was identified during 3 200-2 800 aBP, which just was the transition period from the mid-Holocene climatic optimum toward the late Holocene dry conditions, and the unstable climatic system and the weakening summer monsoon brought out a sharp change of precipitation and caused the occurrence of extreme paleo-flood. This study results are of great scientific significance in understanding the local hydrology change response to global change. References | Related Articles | Metrics