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    10 October 2013, Volume 32 Issue 10
    Effects of temperature on inorganic CO2 flux of saline soil and alkaline soil.
    WANG Zhong-yuan1,2, XIE Jiang-bo1,2, WANG Yu-gang1, LI Yan1
    2013, 32(10):  2525-2531. 
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    Soil CO2 flux and its environmental affecting factors in a saline desert.
    MA Jie1,2,3, YU Dan-dan3,4, ZHENG Xin-jun1,2**
    2013, 32(10):  2532-2538. 
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    Taking the southern Gurbantunggut Desert in Xinjiang as the object, and by using LI-8150 multichannel soil CO2 flux system, a continuous measurement of surface soil CO2 flux under Tamarix ramosissima population in an original saline desert was conducted during growth season, with the diurnal and seasonal variations of the CO2 flux and related environmental affecting factors analyzed. During the whole growth season of the population, the diurnal variation of the CO2 flux presented two distinct patterns, one was single-peaked, and the other was bimodal. The difference in the diurnal variation of the CO2 flux could be mainly caused by the inhibition of soil microbial activity by high temperature. The seasonal variation of the CO2 flux was not apparent, being fluctuated within a stable range (0.13-0.3 g C·m-2·d-1) especially when the diurnal variation was bimodal. When rainfall events happened, the CO2 flux increased in impulse type. During the rainfall cycle, the diurnal CO2 flux varied in bimodal-singlepeaked-bimodal type. Soil moisture content was the main factor limiting the soil CO2 flux in the saline desert.
    Spatial distribution pattern of soil dissolved inorganic carbon in an arid oasis.
    LIU Li-juan, WANG Yu-gang**, LI Xiao-yu
    2013, 32(10):  2539-2544. 
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    Taking Minqin oasis as a case, and by using geostatistics, RS, and GIS, this paper studied the spatial distribution pattern of soil dissolved inorganic carbon (SDIC) in 0-10 cm layer at watershed scale, aimed to understand the dynamic characteristics of SDIC under effects of water and soil in arid areas. In the oasis, the average content of SDIC in 0-10 cm layer was 0.056 g C·kg-1, and the OneSample KolmogorovSmirnov (K-S) test showed that the SDIC content followed normal distribution, and the  spatial distribution of the SDIC could be best fitted by a linear model with the application of variation function. The research based on Kriging method showed that the SDIC content decreased gradually from south to north, being the highest in Baqu, the southeastern part of Minqin oasis, followed by in Quanshan, the central part of the oasis, and the lowest in Huqu, the northern part of the oasis. The landscape maps overlaid land-use types in the same periods showed that the SDIC content in the oasis was mainly ranged in 005-0.06 g C·kg-1, being higher in cropland and sandy land, while lower in forest land, grassland, and saline land. Correlation analysis showed that the SDIC content was significantly positively correlated with HCO3- content, significantly negatively correlated with other salt ions and electrical conductivity, but weakly positively correlated with pH. This study could contribute to the understanding of the dynamic processes of surface soil carbon under effects of water and soil in arid-areas.
    Responses of CO2 flux in a saline desert of Northwest China to two contrasting extreme precipitation years.
    LIU Ran, LI Yan**, LIU Yan
    2013, 32(10):  2545-2551. 
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    Eddy covariance technique was used to measure carbon flux in a desert halophyte community in Fukang of Xinjiang during two hydrological years (2006 and 2007) with contrasting precipitation. The first hydrological year was dry (2006), with the total annual precipitation of 129 mm and the second was wet (2007), with the total annual precipitation of 231 mm. The main objective of this study was to characterize the seasonal and annual carbon flux of a desert halophyte community using the eddy covariance technique to determine the sensitivity of the system to the varying amounts of precipitation. The results showed that the daily carbon absorption rate of the ecosystem was obviously lower in 2006 than in 2007, with the maximum value being -0.4 g C·m-2·d-1 and -1.6 g C·m-2·d-1, respectively. The duration of the growth season was 120 days in 2006, and 160 days in 2007. The carbon absorption, gross ecosystem production (GEP), and ecosystem respiration (Reco) were -5 g C·m-2·a-1, 114.9 g C·m-2·a-1 and 110.1 g C·m-2·a-1  in 2006, and -40 g C·m-2·a-1, 257.7 g C·m-2·a-1 and 218.2 g C·m-2·a-1 in 2007, respectively. The linear relationship between the GEP and ecosystem evapotranspiration was obviously weaker in 2006 than in 2007, with the coefficient of determination being 0.40 and 0.71, respectively. The vegetation community survey revealed that the proportion of annual herbaceous plants in 2007 increased, which could fully utilize precipitation to improve the ecosystem productivity.
    Soil inorganic CO2 flux in relation to soil pH and electric conductivity in saline/alkaline soils.
    WANG Zhong-yuan1,2, XIE Jiang-bo1,2, WANG Yu-gang1, LI Yan1**
    2013, 32(10):  2552-2558. 
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    Soil CO2 flux is the second largest flux of carbon cycle in terrestrial ecosystems, and its slight variation can result in a significant change in the balance of atmospheric CO2 concentration. This paper analyzed the effects of soil pH and electric conductivity (EC) on the soil inorganic CO2 flux, an important component of soil CO2 flux, in saline/alkaline soils. The experiment was conducted at the Fukang Desert Ecological Station, Xinjiang of Northwest China from June to September, 2010. The inorganic CO2 flux of nine saline/alkaline soils was differentiated from the soil CO2 flux by the method of sterilization with high pressure steam chamber. The results showed that for certain saline/alkaline soil, the soil inorganic CO2 flux was mainly controlled by temperature. Low temperature benefited the CO2 absorption by the saline/alkaline soils, whereas high temperature benefited the CO2 release. The soil pH could be used as a good indicator for the soil inorganic CO2 flux. At low and high temperatures, the effects of the soil pH on the soil inorganic CO2 flux differed. The soil salinity also had effects on the soil inorganic CO2 flux, but the effects could be significant only when the soil salinity had a considerable change. This study highlighted the characteristics of soil inorganic CO2 flux in saline/alkaline soils, which could provide evidence to educe the underlying inorganic mechanisms. The nonnegligible role of soil inorganic CO2 flux requires further investigation towards a better understanding of soil carbon cycle in saline/alkaline soils in arid lands.
    Effects of long-term fertilization on soil labile carbon fractions and aggregates in an arid area.
    RONG Jing-rong1,2, ZHONG Wen-shao3, LIU Yan1, WANG Yu-gang1**
    2013, 32(10):  2559-2566. 
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    This paper studied the variation patterns of soil labile organic carbon fractions and water stable aggregates in oasis cropland under effects of different long term fertilization treatments, which could have significance in evaluating oasis cropland soil quality and regional carbon cycle. The study was conducted on an oasis cropland in Xinjiang of Northwest China, and installed four treatments, i.e., long-term (20 years) abandoned cultivation, no fertilization, chemical fertilization, and chemical plus organic fertilization. Cultivation conduced to the accumulation of particulate organic carbon, dissolved organic carbon, dissolved inorganic carbon, and water stable macro-aggregates (>0.25 mm) in surface soil (0-20 cm). As compared with no fertilization, chemical plus organic fertilization more conduced to the accumulation of soil labile carbon fractions and the formation and stability of water stable macro-aggregates. In the same treatments, the particulate organic carbon and water stable macro-aggregates in surface soil played a dominant role to their accumulation throughout the soil profile, while the dissolved organic and inorganic carbon in surface soil had a contrast tendency. There was a significant positive correlation between the soil labile carbon fractions and aggregate stability.
    Variation characteristics of herb layer carbon flux and soil respiration in southern edge of Jungggar basin, Northwest China.
    FAN Lian-lian1,2,3, XIE Ji-ping1,2,3, MA Jian1**, WANG Zhong-yuan1,2,3, ZHAO Hong-mei1,2,3
    2013, 32(10):  2567-2573. 
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    By using LI-840 and LI-8100, this paper measured the carbon flux in herb layer as well as the soil respiration rate in different dune parts in southern Junggar Basin, Northwest China, and studied the seasonal and diurnal variation characteristics of the carbon flux in herb layer, the annual variation characteristics of soil respiration rate in different dune parts, and the effects of environmental factors on the carbon flux and the soil respiration rate. The carbon flux in the herb layer exhibited a unimodal pattern both in diurnal and seasonal scales. The diurnal carbon flux in herb layer had a large fluctuation during vigorous growth season. In the herb layer, the net carbon exchange (NEE) ranged from -2.5 to 0.02 μmol·m-2·s-1, the total productivity (GEP) ranged from -4.4 to -1.1 μmol·m-2·s-1, and the carbon flux after September was maintained at near 0. Through the analysis on the relationships between the carbon flux and environmental factors, it was observed that there was a positive correlation between the herb layer carbon flux and soil temperature and between the soil respiration and PAR, whereas a negative correlation between the GEP and PAR. The annual soil respiration rate in different sand dune parts (top, middle, and bottom) presented a bimodal dynamic pattern, and there existed significant differences in the soil respiration rate among different slope positions.
    Photodegradation of plant litter in a temperate desert along a precipitation gradient.
    HUANG Gang1, ZHOU Li1, TANG Li-song1, LI Yan1**, ZHAO Hong-mei1,2
    2013, 32(10):  2574-2582. 
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    To estimate the effects of photodegradation on the decomposition of plant litter in arid areas of central Asia, three types of litter (Haloxylon ammodendron, Phragmites australis leaves and Triticum aestivum straw) were selected as test objects, and by using litterbag method, a decomposition experiment with UV exclusion and natural light was conducted along a precipitation gradient in the hinterland and southern periphery of Gurbantonggut Desert and the Turpan, Xinjiang of Northwest China. At the three sites, UV exclusion decreased the litter decomposition rate, but the contribution of photodegradation magnitude to the litter decomposition differed because of the different drought extent. UV exclusion reduced the N release from the litter, and the N release dynamics differed with litter type. H. ammodendron and P. australis leaves exhibited N releaseaccumulationrelease pattern, while T. aestivum straw showed N releaseaccumulation pattern. UV exclusion reduced the litter’s hemicellulose loss, but had little effects on the litter’s cellulose and lignin contents. Our study suggested that photodegradation played an important role in the litter decomposition in temperate deserts, and the effect magnitude was dependent on the specific environmental condition and litter quality.
    Photosynthetic responses and biomass allocation strategies of desert herbaceous plants under different precipitation patterns.
    WU Yu1,2,3, ZHENG Xin-jun1,3**, LI Yan1,3, TANG Li-song1,3
    2013, 32(10):  2583-2590. 
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    The responses and adaptation strategies of plants to the variations of precipitation pattern can affect the ecosystem processes such as carbon sequestration. In this paper, a pot experiment was conducted to study the variations of the net photosynthetic rate (Pn), maximum photochemical efficiency of PSII (Fv/Fm), and biomass allocation of four desert herbaceous plants (Kochia scoparia, Atriplex patens, Salicornia europaea, and Salsola lanata) under four simulated precipitation patterns (wet treatments 20 mm × 1 per week versus 10 mm ×2 per week, and drought treatments 12 mm × 1 per week versus 6 mm × 2 per week). Overall, the Pn of the plants peaked on the 2nd day after the treatments, and the plants maintained a higher level of single leaf Pn. The Fv/Fm of S. europaea and S. lanata in all treatments was kept within an optimal range. The specific leaf area (SLA) and specific root length (SRL) were less affected by the treatments. The growth of K. scoparia was limited by phosphorus, while that of the other three species was limited by nitrogen. The precipitation amount dominated the total biomass and the leaf, shoot, and root biomass, whereas the precipitation frequency regulated the biomass allocation in plant above and belowground parts. Under a given precipitation amount, the increase of precipitation frequency promoted more biomass allocation in plant belowground part.
    Photosynthetic responses of different plant functional types to small rainfall events in a non-disturbed desert.
    WU Yu1,2,3, ZHENG Xin-jun1,3**, LI Yan1,3
    2013, 32(10):  2591-2597. 
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    In arid areas, small rainfall (≤5 mm) events account for a large proportion of annual precipitation frequency, and occur in short time intervals. To elucidate the possible strategies of desert plants in utilizing small rainfall, this paper studied the photosynthetic responses of 28 plant species to simulated 1 and 6 mm rainfalls in Junggar Basin of Northwest China. For comparison, the 28 species were grouped into four plant functional types, i.e., herbaceous plants with short life cycle, herbaceous plants with long life cycle, nonphreatophyte shrubs, and phreatophyte shrubs. The results showed that after 1 mm rainfall, the net photosynthetic rate (Pn) and stomatal conductance (gs) of most herbaceous plants increased, while the gs of nonphreatophyte shrubs and the instantaneous water use efficiency (WUE) of phreatophyte shrubs had a response magnitude similar to that after 6 mm rainfall. In order to explore the possible mechanisms of small rainfall utilization, the leaf water uptake content (LWUC) and the percentage increase of leaf water content (Rw) were measured for assessing the leaf water uptake capacity of all the test species. The results revealed that most herbaceous plants with trichomes could directly absorb small rainfall, while shrubs could be indirectly benefited via increasing the humidity of microhabitat, regulating stomatal conductance, and reducing transpiration.
    Safety vs. efficiency trade-off in xylem hydraulic conductance system controls plant biomass allocation: A case study of cotton acclimation to soil texture.
    XIE Jiang-bo1,2, ZHONG Wen-zhao3, WANG Zhong-yuan1,2, XU Gui-qing1, WANG Yu-gang1, LI Yan1**
    2013, 32(10):  2598-2605. 
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    The development of phenotype is restricted by the geometry of plant vascular network. In different environments, plant vascular network makes the structural and functional tradeoff between efficiency and safety, develops different network characters, and thus, induces the plastic responses of phenotype. Despite the importance of vascular network structural acclimation in modifying plant phenotype, this topic has largely been neglected. In this paper, an environmental gradient of three soil textures (sandy soil, clay soil, and 1∶1 sandy soil and clay soil) was installed to study the effects of soil texture on the geometry of root and stem xylem vessels of cotton (Gossypium herbaceum L.) plants as well as the relationships among soil texture, xylem vessel size, and biomass allocation. The results showed that long-term exposure to the soil texture gradient led to a significant change in the vessel traits. The comparison of the plants in the three treatments indicated that the structural differences of the vessels could significantly affect (or wererelated to) the root, shoot, and whole plant hydraulic conductance, end-wall resistance, leaf area, and plant height. These results demonstrated that an increased soil particle size tended to result in a safer hydraulic system rather than a more efficient hydraulic system (safety and efficiency tradeoff).
    Estimation of pan evaporation in southeastern Junggar Basin of Northwest China based on Thom-Thony-Vauclin Model.
    ZHENG Xin-jun**, WANG Yu-gang, LI Yan
    2013, 32(10):  2606-2613. 
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    By using the observed data of daily solar radiation and pan evaporation from E601B evaporation pan at Fukang Desert Ecological Station, Xinjiang of Northwest China, the empirical parameters of Angstrom-Prescott Model and Thom-Thony-Vauclin Model were calibrated, respectively, aimed to analyze the possible reasons of the descend of pan evaporation in southeastern Junggar Basin under the scenario of past five decades climate change. When as=0.3134 and bs=0.5357, and a=0.6844 and c=1.4123, the Angstrom-Prescott Model and Thom-Thony-Vauclin Model preformed the best fitness, respectively. The calculation with Thom-Thony-Vauclin Model showed that the sum of pan evaporation in the plant growth season (April-October) in 2005-2011 ranged from 954.2 mm to 1120.0 mm, with an average of 1028.4 mm. For the variation of pan evaporation, wind speed descending contributed most (66.2%), air temperature ascending and solar radiation descending contributed 21.2% and 8.0%, respectively, whereas vapor pressure deficit descending contributed least (5.9%). Except that the relative sensitivity decreased with the increase of net radiation, the other three indicators showed opposite trends. Consequently, wind speed descending could be the most possible reason for the pan evaporation paradox in southeastern Junggar Basin.
    Dynamic predication of soil salinization in an oasis at lower reaches of inland river basin, Xinjiang of Northwest China.
    LIU Li-juan, WANG Yu-gang**, TANG Li-song
    2013, 32(10):  2614-2619. 
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    Aiming at the serious soil salinization in arid oasis, GIS and RS techniques were adopted to study the salinization characteristics in topsoil (0-20 cm) in an oasis at the lower reaches of the Sangong River Basin in the northern piedmont of the Tianshan Mountains in Xinjiang of Northwest China, and a spatial probability model was used to predict the dynamic status of the soil salinization. After a long-term land use process, the soil salinization in the study area aggravated to some extent, and the area of soil salinization was enlarged. The χ2test of spatial probability model revealed that the simulated value of transition probability and the measured value were more reliable during the period of 1982-2005 than during the period of 1982-1999. The simulated results of spatial probability model showed that after 2010, the area of natural landscapes was reduced, but that of artificial ones was enlarged, in which, the area of slight soil salinization was decreased, but that of moderate and serious soil salinization showed an opposite pattern. It was considered that within a long period, soil salinization would be still a key factor limiting the cropland productivity in the study area.
    Soil salt components and their spectral characteristics in Minqin Oasis of Northwest China.
    ZHANG Jian-ming1**, QI Wen-wen2,3
    2013, 32(10):  2620-2626. 
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    Based on field sampling and laboratary analysis, this paper studied the characteristics of soil soluble salts in Minqin Oasis of Northwest China. The dominant anions in the surface soil were Cl- and SO42-, and the main cations were Ca2+ and Mg2+. The correlation coefficients of the SO42- with the Ca2+ and Mg2+ were 0.918, and 0.933, respectively, illustrating that the SO42- was mainly combined with the Ca2+ and Mg2+. There was a higher precision when using linear equation to fit the relationships between the soil electrical conductivity and soil total salt content. Through the measuremnt of surface soil extract spectra and the analysis of surface soil spectral characteristics, it was found that the two transformations of firstorder differentiation of reflectivity and logarithmic reflectivity had the strongest correlations with the soil total salt content. The soil total salt content was further predicted by multiple linear regressions, and the regression equation with the firstorder differentiation of logarithic reflectance as the independent variable had the best effect, with the   determination coefficient  (R2) being 0.789.
    Net ecosystem carbon exchange in saline desert: A comparison of eddy covariance method and chamber-based method.
    MA Jie1,2,3, WU Yu1,2,3, ZHENG Xin-jun1,2**, TANG Li-song1,2, WANG Yu-gang1,2
    2013, 32(10):  2627-2634. 
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    By coupling the seasonal variation of leaf area index (LAI) with the synchronous chamber-based measurement of leaf net photosynthesis (respiration) rate and soil CO2 flux, the ecosystem carbon exchange in a saline desert was estimated, and the results were used to verify the reliability of eddy covariance data. The annual total leaf biomass of the saline desert ecosystem was 51.30±5.56 g·m-2, of which, more than 90.45% were contributed by Tamarix ramosissima. In the whole growth season, the LAI varied in single peak pattern, being 0.18-0.30 from the 30th of May to the 30th of September and peaked at the 197th day. The measurement of the carbon flux by eddy covariance method and chamber-based method showed that the net ecosystem carbon exchange had an obvious seasonal variation, which peaked in mid-July and had significant correlation with LAI (P<0.001). Through comparison, the daytime ecosystem carbon exchange from eddy covariance measurement was agreed well with that from chamberbased measurement, but the nighttime ecosystem carbon exchange from eddy covariance measurement was slightly underestimated, probably due to the weak turbulence during the night.
    Fine root production and turnover of Alhagi sparsifolia community in arid area of Xinjiang, Northwest China.
    JI Wei-ping1, WANG Jian-jian2,3**, ZHAO Xue-chun2,3, LAI Li-ming2, WANG Yong-ji2,3, MA Yuan-jian4, ZHAO Chun-qiang4, ZHENG Yuan-run2
    2013, 32(10):  2635-2640. 
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    Fine root plays a key role in the water and nutrient uptake by plants. To accurately understand the fine root production, turnover, and decomposition is crucial for studying the carbon budget in terrestrial ecosystem. Taking the Alhagi sparsifolia community, a typical plant community in arid area of Xinjiang, as test object, and by using soil core sampling and fine root litterbags, this paper studied the fine root amount, its spatiotemporal variation, and decomposition and turnover patterns in the growth period (from May to October, 2010) of the A. sparsifolia. The monthly average fine root biomass of the community was 93.10 g·m-2, of which, live and dead ones accounted for 72.72% and 27.28%, respectively. The fine root biomass showed an obvious seasonal variation trend, i.e., increased from May, peaked in late August, and declined gradually from September to October. 72.22% of live roots and 76.66% of dead ones were distributed in 0-30 cm soil layer, 13.82% of live roots and 13.39% of dead ones were distributed in 30-40 cm soil layer, and a little proportion of live roots were in the soil layers below 40 cm. The annual decomposition rate of fine roots was 64.52%, and it took 228 days and 916 days to decompose 50% and 95% of the total fine roots, respectively. The annual net production of fine roots was 118.81 g·m-2·a-1, and the annual turnover rate of fine roots was 1.75 cycles·a-1. All the results showed that the fine root production of the A. sparsifolia community varied significantly with season and soil depth, and, due to the lower decomposition rate but higher turnover rate, the fine roots of A. sparsifolia community had great significance in the distribution pattern of underground carbon cycling in arid area ecosystem.
    Spatial distribution of horizontal lateral roots of Populus pruinosa Schrenk in relation to clonal reproduction.
    ZHENG Ya-qiong1,2, ZHOU Zheng-li1,2, LI Zhi-jun1,2**
    2013, 32(10):  2641-2646. 
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    Populus pruinosa only naturally distributes in the Tarim basin of Xinjiang, Northwest China. In this paper, field investigation and laboratory analysis were conducted on the adults, samplings, and 1-year old seedlings of P. pruinosa, aimed to understand the spatial distribution of the clonal reproduction organs of P. pruinosa and the relationships of this distribution with clonal reproduction. The clonal reproduction organs of P. pruinosa were all the first order horizontal lateral roots on the taproots. The clonal reproduction organs and taproots formed in nearly 90 degree angle, and carried on vegetative growth and horizontal expansion in soil until they grew to a certain stage and penetrated vertically at particular space sites. The same taproots had different first order horizontal lateral roots, whose horizontal expansion parts were in the 10-100 cm soil layer and concentrated in the 20-40 cm layer. Different horizontal lateral roots had different distribution depth, extending direction, and expansion distance in soil, and even, different sections of the same horizontal lateral roots also had different distribution depth, extending direction, and expansion distance in soil. In different habitats, P. pruinosa could generate the horizontal lateral roots with almost unanimous vertical distribution. The generated horizontal lateral roots could produce clonal ramet, and were mainly distributed in the 5-30 cm soil layer. Underground water level could affect the occurrence of the clonal reproduction of horizontal lateral roots.
    Characteristics of energy distribution of Pinus tabulaeformis and Quercus aliena var. acuteserrata communities along an altitudinal gradient.
    LI Jing-jing1,2, DANG Kun-liang1,2**, TANG Peng-hui1,2
    2013, 32(10):  2647-2653. 
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    In this paper, the biomass, caloric value, ash content, and carbon content of natural Pinus tabulaeformis and Quercus aliena var. acuteserrata communities along an altitudinal gradient on the southfacing slope of middle Qinling Mountains, China were determined, aimed to explore the distribution patterns of the two communities’ biomass and energy at different altitudes. With the increase of altitude, the standing biomass and energy of the two communities decreased after an initial increase. The total biomass of P. tabulaeformis and of Q. aliena var. acuteserrata was the highest at altitude 1500-1600 m and 1400-1500 m, being 263.94
     t·hm-2 and 278.71 t·hm-2, respectively, while the total energy was all the highest at altitude 1400-1500 m, being 5715.38 GJ·hm-2 and 5756.13 GJ·hm-2, respectively. At the same altitudes, the caloric value and carbon content of P. tabulaeformis were higher than those of Q. aliena var. acuteserrata, but the ash content was in opposite. The caloric value and average caloric value of different organs of P. tabulaeformis increased with increasing altitude, while those of the bark of Q. aliena var. acuteserrata were in adverse. The average carbon content of P. tabulaeformis and of Q. aliena var. acuteserrata increased with increasing altitude, while the ash content had no regularity. The caloric value, ash content, and carbon content of P. tabulaeformis at different altitudes were 2039-21.47 kJ·g-1, 2.81%-3.54%, and 46.20%-50.50%, while those of Q. aliena var. acuteserrata were 19.69-20.18 kJ·g-1, 6.15%-7.77%, and 42.06%-44.15%, respectively. For P. tabulaeformis, significant differences were found in the caloric value and carbon content at different altitudes, but little difference was observed in the ash content. For Q. aliena var. acuteserrata, significant differences were found in the ash content and carbon content at different altitudes, but little difference was observed in the caloric value. It was considered that the microhabitat at medium altitude was more appropriate for the growth of P. tabulaeformis and Q. aliena var. acuteserrata.
    Distribution patterns of carbon density in different tree species plantations in a subtropical area of China.
    ZHENG Lu1,2**, CAI Dao-xiong1,2, LU Li-hua1,2, MING An-gang1,2, LI Zhao-ying1, LI Li-li1
    2013, 32(10):  2654-2658. 
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    By using combustion method, this paper measured the carbon density in the tree, shrub, herb, and litter layers of six tree species plantations in a subtropical area of China. For the six plantations, the carbon density in different parts of trees varied, being the highest in leaf and trunk, followed by in branch, and the lowest in root and bark. Among the tree species, Pinus massoniana had the highest carbon density, while Mytilaria laosensis and Castanopsis hystrix had the lower one. The carbon density in different parts of understory shrubs had significant difference, with a similar pattern to that in different parts of trees, i.e., being the highest in leaf and branch, and the lowest in root. With the increasing density of the stands, the carbon density of understory shrubs presented a decreasing trend. In herb layer, the carbon density was higher in aboveground part than in belowground part, and had a similar distribution pattern to that in different parts of understory shrubs. In litter layer, the carbon density decreased rapidly from un-decomposed layer to semi-decomposed layer to humus layer. In the stand components, the carbon density was in the order of tree layer > shrub layer > herb layer > litter layer.
    Effects of four kinds of Larix gmelini root exudates on the root activity and mycorrhizal infection incidence of Juglans mandshurica.
    SU Jin-bao1, WANG Dong-liang2, YANG Li-xue3**
    2013, 32(10):  2659-2664. 
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    A pot experiment was conducted to study the effects of applying four kinds of Larix gmelini rhizosphere and bulk concentration root exudates from a Juglans mandshuricaL. gmelini mixed plantation on the root activity and mycorrhizal infection incidence of J. mandshurica. In the treatments of applying rhizosphere concentration root exudates, 2,4-2 hydroxy benzoic acid and ferulic acid improved the J. mandshurica root activity and mycorrhizal infection incidence by 33.5% and 10.7%, and 6.8% and 5.7%, respectively, while the other treatments decreased the root activity and mycorrhizal infection incidence, as compared with the control. In the treatments of applying bulk concentration root exudates, the J. mandshurica root activity and mycorrhizal infection incidence had a greater change, being increased or decreased, as compared with the control. Both the rhizosphere and the bulk concentration 2,4-2 hydroxy benzoic acid promoted the growth of J. mandshurica. The correlation analysis showed that there existed significant correlations between J. mandshurica root activity, mycorrhizal infection incidence, and biomass, with the correlation coefficients being 0.897, 0.91 and 0.877, and 0.912, 0.894 and 0.917, respectively, indicating that higher root activity and mycorrhizal infection incidence promoted the growth of J. mandshurica.
    Interspecific associations among dominant tree populations in an elfin forest community in Shikengkong of Nanling Mountains, China.
    HU Wen-qiang1, HUANG Shi-neng1, LI Jia-xiang2, ZHOU Guang-yi1, WANG Xu1**
    2013, 32(10):  2665-2671. 
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    There distributes typical elfin forest community in Shikengkong of Nanling Mountains, but little is known about the interspecific relationships between the dominant tree species in the community. By using 2×2 contingency table, variance analysis, association index, χ2text, Pearson’s correlation coefficient, and Spearman’s rank correlation test, this paper quantitatively studied the interspecific associations of 120 species pairs of 16 dominant tree populations with higher importance value. The results of variance analysis showed that there existed significant positive correlations among the 16 dominant species, suggesting that this community was at a more stable climax stage. The χ2 test illustrated that there were 66 species pairs in positive association, and 54 species pairs were in negative association, with the ratio of positive to negative association being 1.22. The Pearson’s correlation coefficient test displayed that 65 species pairs were in positive association, and 55 species pairs were in negative association, with the positive/negative association ratio being 1.18. The Spearman’s rank correlation coefficient test reflected that 64 species pairs were in positive association, while 56 species pairs were in negative, with the positive/negative association ratio being 1.14. The association index showed that most species pairs had lower degree of association. Among the 120 species pairs, most pairs did not show significant association, which could be due to their ecological characteristics and the seral stage of the community. This forest community was at the late-successional stage and quite stable.
    Spatial patterns of Quercus wutaishanica seedlings and their microhabitats in Ziwuling Mountains of Loess Plateau.
    FAN Wei-yi, GUO Hua**, WANG Xiao-an, WANG Shi-xiong
    2013, 32(10):  2672-2678. 
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    By the methods of geostatistics, this paper studied the spatial patterns of Liaodong oak (Quercus wutaishanica) seedlings and their microhabitats in two kinds of forests (Liaodong oak forest and Pinus tabulaeformis plantation) in the Ziwuling Mountains of Loess Plateau, and the relationships between the Liaodong oak seedlings and their microhabitat factors. In the two forests, Liaodong oak seedlings were in clumped distribution, but the clumped scale existed greater difference. The seedlings were spatially autocorrelated in 1-5.94 m range in Liaodong oak forest, while in 1-1.94 m range in P. tabulaeformis plantation. By using forward selection method and Detrended Canonical Correspondence Analysis (DCCA), 14 microhabitat factors were selected. In Liaodong oak forest, the main microhabitat factors affecting the spatial pattern of Liaodong oak seedlings were litter thickness, soil available potassium content, and soil temperature. In P. tabulaeformis plantation, the main microhabitat factors were soil humidity, pH, and organic matter content. It was deduced that the microhabitat difference in seedling’s establishment could be an important factor which caused the heterogeneity of the seedling’s spatial pattern.
    Effects of slope aspect and altitude on the soil seed bank under different vegetations in Laji Mountains of Qinghai Province, Northwest China.
    HUANG Rui-ling1,2, ZHOU Hua-kun1**, LIU Ze-hua2, LEI Zhan-lan2, YAO Bu-qing1, WANG Xin-chuan3, WANG Wen-ying2, ZHAO Xin-quan1
    2013, 32(10):  2679-2686. 
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    In May (spring) and October (autumn), 2006, an investigation was conducted on the soil seed bank at different altitudes (3100-3920 m) and slope aspects (sunny slope, shady slope, and ridge) in the Laji Mountain of Qinghai, aimed to study the effects of slope aspect and altitude on the distribution pattern of the soil seed bank. The species life forms in the soil seed bank were similar in spring and autumn, mainly dominated by perennial herbs, followed by annual herbs, and deciduous shrub rarely appeared. The storage and species composition of the soil seed bank increased with altitude and presented a decreasing trend on the sunny slope and shady slope, but had more obvious fluctuation on the sunny slope. The storage of the soil seed bank was the minimum on the ridge. The soil seed bank in vertical direction had a diminishing pattern. The seeds were mainly distributed in 0-3 cm soil layer, followed by in 3-6 cm soil layer, and decreased gradually with increasing soil depth. The storage of the soil seed bank had seasonal dynamics, being greater in  October (seed-rain finished season) than in May (seed germination season).
    Soil organic carbon and mineralizable organic carbon in four subtropical forests in hilly region of central Hunan Province, China.
    GU Xiang1, FANG Xi1,2**, XIANG Wen-hua1,2, LI Sheng-lan1, SUN Wei-jun1
    2013, 32(10):  2687-2694. 
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    A short-term laboratory incubation was conducted to study the variations of soil organic carbon and mineralizable organic carbon concentrations in four forest stands (Cunninghamia lanceolata plantation, Pinus massoniana + Lithocarpus glaber mixed forest, Choerospondias axillaries deciduous broadleaved forest, and L. glaber + Cyclobalanopsis glauca evergreen broadleaved forest) in a hilly region of central Hunan Province. In the four forest stands, the concentrations of soil organic carbon and mineralizable organic carbon and the proportion of soil mineralizable organic carbon to soil total organic carbon decreased with soil depth. In the same soil layers, the concentration of soil organic carbon ranked in the order of L. glaber + C. glauca evergreen broadleaved forest > P. massoniana + L. glaber mixed forest > C. axillaries deciduous broadleaved forest > C. lanceolata plantation. In 0-30 cm soil layer, the organic carbon concentration in the secondary forests was 20.8%-31.9% higher than that in C. lanceolata plantation. The concentration and the proportion of soil mineralizable organic carbon were in the order of L. glaber + C. glauca evergreen broadleaved forest > C. axillaries deciduous broadleaved forest > P. massoniana + L. glaber mixed forest > C. lanceolata plantation. The soil mineralizable organic carbon concentration in L. glaber + C. glauca evergreen broadleaved forest, C. axillaries deciduous broadleaved forest, and P. massoniana + L. glaber mixed forest was 51.6%, 45.2%, and 41.0% higher than that in C. lanceolata plantation, and the proportion of mineralizable organic carbon in 0-30 cm soil layer in the former three secondary forests was 35.8%, 29.3%, and 20.0% higher than that in C. lanceolata plantation, respectively. In the four forest stands, soil mineralizable organic carbon had significant correlations with soil total organic carbon, microbial biomass carbon, total nitrogen, and the ratio of total organic carbon to total nitrogen.
    Responses of organic carbon mineralization in typical soils in northwest Guangxi of China to calcium carbonate and soil moisture.
    HUANG Yuan1,2,3, SU Yi-rong1,3, LIANG Shi-chu2, CHEN Xiang-bi1,3, HE Xun-yang1,3**
    2013, 32(10):  2695-2702. 
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    In order to understand the effects of soil moisture  on  organic carbon (OC) mineralization in two typical soils in Northwest Guangxi of China under the existence of calcium carbonate, a 100day incubation experiment with the topsoil (0-15 cm) of terra fusca in Karst region and of zonal red soil (as a control) was conducted to study the characteristics of soil OC mineralization under the conditions of three soil moisture gradients (30%, 65%, and 100% waterholding capacity; W1, W2, and W3) and a fixed added calcium carbonate quantity (50 g Ca14CO3·kg-1 dry soil) at 25 ℃. After 100day incubation, the contribution rate of the 14CCO2 from added calcium carbonate to the apparent accumulative mineralization amount under W1, W2, and W3 was 9.64%, 6.01%, and 7.63% for the terra fusca, and 34.05%, 27.73%, and 24.18% for the red soil, respectively. The soil OC mineralization rate and accumulative mineralization amount were in the order of W2 > W1 > W3 (P<0.05) for the terra fusca, and of W2, W3 > W1 (P<0.05) for the red soil, respectively. Soil moisture, soil type, and their interaction had significant effects on the soil OC mineralization rate and accumulative mineralization amount (P<0.05). Therefore, when studying the OC mineralization in carbonate-rich soils, especially for the calcareous soils developed in Karst geological background, it would be necessary to consider the effects of soil moisture content and inorganic carbonate decomposition on the soil OC mineralization, and to incorporate these effects into C cycle model to accurately assess the effects of soil inorganic carbon on the soil OC pool.
    Characteristics of plant community and its functional groups in desert grassland under effects of seasonal regulation of grazing intensity.
    SUN Shi-xian1, WEI Zhi-jun1**, LU Shi-jie1, LU Zhi-hong1, CHEN Li-bo3, LI Xia-zi1, WU Yan-ling2, LI Jian-ru4
    2013, 32(10):  2703-2710. 
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    Taking the Stipa breviflora desert grassland in Inner Mongolia as test object, a randomized block experiment was conducted to reveal the changes in the aboveground biomass of plant community, its diversity, the biomass of functional groups, importance value, and variation coefficient under the effects of the seasonal regulation of six grazing intensities. In the treatment of zerograzing in spring, severe grazing in summer and moderate grazing in autumn, the aboveground biomass and Shannon diversity index were significantly higher than those of the other treatments. In the treatments of zerograzing in spring, light grazing in summer and moderate grazing in autumn and of severe grazing in spring, severe grazing in summer and light grazing in autumn, the biomass of perennial grasses was significantly lower than that in other treatments and CK. The biomass of the annual and biennial forbs showed negative correlations with those of the perennial grasses, shrubs, semishrubs, and perennial forbs; while the biomass of perennial forbs was significantly positively correlated with those of perennial grasses, shrubs, and semi-shrubs. The importance value of the shrubs and semi-shrubs in the treatment of severe grazing in spring, severe grazing in summer and light grazing in autumn was significantly higher than that in other treatments and CK. The variation coefficient of the community biomass was the lowest (averagely 29%), that of the perennial forbs and perennial grasses was lower (averagely 49% and 56%, respectively), and the variation coefficient of the shrubs and semi-shrubs and of the annuals and biennials was higher (averagely 79% and 105%, respectively). It was suggested that the treatment of zero-grazing in spring, light grazing in summer and moderate grazing in autumn would be the more reasonable seasonal regulation mode of grazing intensity.
    Niche characteristics of ‘noxious and miscellaneous grass type’ degraded grassland on northern slope of Qilian Mountains, China.
    REN Heng1**, ZHAO Cheng-zhang2, AN Li-juan3
    2013, 32(10):  2711-2715. 
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    By using niche theory, this paper analyzed the niche characteristics of ‘noxious and miscellaneous grass type’ degraded grassland on the northern slopes of the Qilian Mountains under the grazing disturbance of Stipa krylovii grassland. In the degraded grassland of ‘noxious and miscellaneous grass type’, the constructive species (S. krylovii) and the main accompanying species (Stellera chamaejasme and Melica przewalskyi) had the similar higher importance value. The niche breadth of Aneurolepidium dasystachys and S. chamaejasme was 0.925 and 0.922, respectively, being greater than that of the other species, while the niche breadth of
    S. krylovii was only 0.669. There were 207 species pairs having the niche overlapping index over 0.05, indicating a lower niche polarization of the populations. The niche of the degraded grassland had some special characters different from other degraded grassland types, which could be related to the changes of community microenvironment, the resistance strategies of the populations against the microenvironment changes, and the populations themselves adaptability, reflecting the adaptive approaches of the populations to the regeneration under grazing disturbance.
    Functional groups of herbaceous plants in the lower reaches of Fenhe River basin in Shanxi Province, China.
    FAN Xiao1, ZHANG Feng2, PANG Chun-hua1**, AI Ying1, HOU Lu-dan1, CHENG Xue-lian1
    2013, 32(10):  2716-2720. 
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    By using the survey methodology of community ecology, a total of 85 sampling plots were installed in the lower reaches of Fenhe River Basin in Shanxi. According to the occurrence frequency of the investigated herbaceous species, 21 dominant species were selected for interspecies association analysis. The associations between dominant species were determined based on the χ2 inspection and in light of the association coefficient (AC) and the percentage co-occurrence (PC). The functional groups of herbaceous plants in the study area were classified by the associations between dominant species and the variations of moisture gradient. Overall, the 210 species pairs formed by the dominant species showed negative association, but the vast majority of the species pairs showed weak association and non-association. Four herbaceous plant functional groups were classified, i.e., aquatic, hygrophyte, mesoxerophyte, and invasive. Significant positive association was shown between the species in the same functional groups, and negative association or nonassociation was shown between the species of different functional groups.
    Crop yield response to different tillage modes combined with fertilization measures.
    ZHANG Jian-sheng, SUI Peng, CHEN Yuan-quan**, GAO Wang-sheng, NIE Zi-jin, ZOU Juan-xiu, SHI Yan-qin, XIONG Jie, WANG Hong-jiao
    2013, 32(10):  2721-2727. 
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    A3year (2009-2012) field experiment was conducted in Wuqiao County of North China Plain to study the crop yield response to different tillage modes combined with fertilization measures. Four tillage modes (rotary tillage, RT; subsoiling, ST; plough tillage, PT; no-tillage, NT) combined with three fertilization measures (manure and chemical fertilization, MF; straw returning and chemical fertilization, SF; chemical fertilization, CF) were installed, and wheat and maize were selected as test crops. Under 3year continuous tillage, the wheat yield was in the sequence of PT > ST > RT > NT, and the maize yield was in the order of RT > ST > NT > PT. When tillage was conducted in wheat season in the second year and notillage was conducted in maize season in the third year, the highest average yield of wheat and maize was observed in the treatment of sub-soiling in wheat season and in the treatment of no-tillage in maize season. When no-tillage was conducted in maize season in the second year and in wheat season in the third year, sub-soiling had the highest wheat yield, while rotary tillage had the highest maize yield. Based on the results under different tillage modes, continuous notillage for two and three years was not conducive to wheat yield improvement, and even, caused the yield decreased. However, continuous no-tillage for two and three years had less impact on maize yield, and even, could improve maize yield. As for the fertilization measures, the crop yield response in three years was consistent, and the average crop yield was in the sequence of MF > SF > CF. These results indicated that the appropriate tillage mode and fertilization measure conducive to the crop yield stability in North China Plain could be the “sub-soiling in wheat season and no-tillage in maize season combined with manure application”, under which, the crop yield could be increased by 10.6%, as compared with the widely adopted pattern (rotary tillage in wheat season and no-tillage in maize season combined with straw returning) in this area.

     
    Feeding behaviors of darkbarbel catfish (Peletobagrus vachelli Riehardson) in spawning ground of Chinese sturgeon in lower reaches of Gezhouba Dam, China: A laboratory study.
    LU Bo1, BAI Yan-qin1, LUO Jia1, LIU De-fu1, SHI Xiao-tao1,2,3**, CHEN Qiu-wen1,2, HUANG Ying-ping1
    2013, 32(10):  2728-2734. 
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    Darkbarbel catfish (Peletobagrus vachelli) is one of the major predatory fishes feeding on the eggs of Chinese sturgeon. In this paper, the wild darkbarbel catfish population (body length 14.34±5.16 cm, body mass 61.29±23.62 g) was collected from the lower reaches of Gezhouba  Dam, and a laboratory experiment was conducted to study the feeding preference, locomotion, and feeding circadian rhythm of the population under the conditions of natural day/night rhythm and water temperature 20.6 ± 0.5 ℃ and with the baits of earthworm (Pheretima sp.), commercial pellet, dried tofu, fish (Pseudorasbora parva), shrimp (Macrobranchium nipponense), and sweet potato, aimed to search for the countermeasures to reduce the predation of darkbarbel catfish on the eggs of Chinese sturgeon. No significant differences were observed in the percentages of the preference to the six kinds of baits, but the feeding rate of darkbarbel catfish on earthworm, fish, and shrimp was significantly higher than that on tofu, sweet potato, and commercial pellet. Under no bait addition, the locomotion level of the darkbarbel catfish could be defined as active period (18:00-22:00), subactive period (22:00-7:00), and non-active period (7:00-18:00), with significant differences among the three periods. Under bait addition, the locomotion level of the darkbarbel catfish could be defined as activity period (18:00-5:00) and non-activity period (5:00-18:00), with significant differences between the two periods. The feeding activity level of the darkbarbel catfish was classified into feeding period (17:00-5:00) and non-feeding period (5:00-17:00), with significant differences between the two periods. It was concluded that darkbarbel catfish preferred to feed earthworm, fish, and shrimp, and the locomotion and feeding rhythms of the darkbarbel catfish were of nocturnal, with the locomotion level disturbed by baits.
    Relationships between shorebirds and macrobenthos in Sheyang Estuary of Yancheng Reserve, East China in spring.
    HOU Sen-lin1, YU Xiao-yun2, LU Chang-hu2**
    2013, 32(10):  2735-2743. 
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    In the spring of 2009, an investigation was conducted on the relationships between shorebirds and macrobenthos in the Sheyang Estuary of Yancheng Reserve from the viewpoints of shorebirds bill length and foraging strategy. The high, medium, and low tidal flats without plants, intertidal zone with Spartina alterniflora, and the bank of creek without S. alterniflora were selected as the test habitats. In the study area, Bivalve and Crustacean were the main macrobenthos, whose distribution was basically the same as the distribution of shorebirds. The densities of the shorebirds with a bill length of >50 mm were significantly positively correlated with that of Crustacean, while the densities of the shorebirds with a bill length of <25 mm were significantly positively correlated with those of Bivalve and total macrobenthos. No significant correlations were observed between the densities of the shorebirds with a bill length of 25-50 mm and those of several forms of macrobenthos. The density of visual continuous shorebirds was positively correlated with that of Crustacean, and the density of tactile continuous shorebirds was positively correlated with the densities of Bivalve and total macrobenthos. However, the density of pause-travel shorebirds had less correlation with those of several forms of macrobenthos. The percentages of the shorebirds with a bill length of >50 mm and 25-50 mm were positively correlated to the percentages of epifauna life forms, but negatively correlated to the percentages of infauna life forms, whereas the percentages of the shorebirds with a bill length of <25 mm were positively correlated to infauna and negatively correlated to epifauna life forms. The percentages of the shorebirds with visual continuous and pausetravel foragingstrategies were positively correlated to the percentages of epifauna and negatively correlated to infauna life forms, whereas the percentage of the shorebirds with tactile foraging-strategy was positively correlated to infauna and negatively correlated to the epifauna life forms, but the correlations were not significant.
     
    Distribution characteristics of zooplankton in National Aquatic Germplasm Conservation Area in Lüsi fishing ground of East China in spring and summer.
    YU Wen-wen, LIU Pei-ting, GAO Yin-sheng, GAO Ji-xian, WU Fu-quan, TANG Jian-hua**, WU Lei, SHI Jin-jin
    2013, 32(10):  2744-2749. 
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    Two navigation surveys in May (spring) and August (summer) of 2010 were conducted to investigate the species composition, abundance distribution, dominant species, and species diversity of diet zooplankton in the national protection area of aquatic germplasm in Lüsi fishing ground. In the study area, the abundance of diet zooplankton was higher in spring (163.1 ind·m-3) than in summer (46.3 ind·m-3), while the biomass was higher in summer (699 mg·m-3) than in spring (324 mg·m-3). Both the abundance and the biomass of the zooplankton were higher in the southwest than in the northeast. The dominant species in both spring and summer were Calanus sinicus, Labidocera euchaeta, Sagitta nagae, and Pseudeuphausia sinica. C. sinicus was in absolute superiority, followed by L. euchaeta. The index of species diversity was lower in summer (2.27) than in spring (2.51). Overall, the zooplankton community had a stable structure, which provided basis for supplying rich feedstuffs to the fishes, especially juvenile fishes, in this conservation area.
    Spatiotemporal distribution patterns of elver (Anguilla japonica) in the Yangtze River Estuary of China.
    ZHI Yu-long1,2, HOU Jun-li1, ZHANG Tao1, ZHANG Long-zhen1, ZHAO Feng1, YANG Gang1, ZHUANG Ping1,2**
    2013, 32(10):  2750-2755. 
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    Based on the investigation data of anguillid elver (Anguilla japonica) at eight sampling sites in the waters of Dongwangsha, Sheshan Island, Qingcaosha, Dongfeng Xisha, Jiuduansha, and Nanhui of the Yangtze River Estuary in January-April, 2012, this paper studied the spatiotemporal distribution patterns of the elver in the Yangtze River Estuary. It was found that in 2012, the peak period of glass eel catch was from February to March, and gradually postponed from south to north and from the external to the internal of the estuary water. The spatiotemporal distribution patterns of the elver were accorded with its migrating route in the estuary. The main distribution areas of elver were the external waters of the Yangtze River Estuary, such as Nanhui, Sheshan Island, and Dongwangsha. Nanhui waters had the maximum catching quantity. Comparably, Qingcaosha and Dongfeng Xisha waters located inside of the estuary had lesser catching quantity. The fixedpoint monitoring and questionnaire surveys indicated that the total catch of glass eel in the Yangtze River Estuary was inferred nearly to 16.8 million individuals, with the output value being 50 million Yuan RMB. For the sustainable use of anguillid elver in the Yangtze River Estuary, it was suggested that the elver fishing time should be limited from February to March, and the elver fishing waters should be limited to the areas from Nanhui to Sheshan Island.
    Seasonal variation of zooplankton copepod community in Xiangshan Bay of East China.
    DU Xiu-ning, WANG Yun-long**, CHEN Tao, LIAO Yong
    2013, 32(10):  2756-2763. 
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    In the spring (April), summer (July), and autumn (October) of 2011, investigations with types Ⅰ and Ⅱ of plankton net were conducted on the zooplankton in Xiangshan Bay, with the species composition, abundance, and community structure of the dominant zooplankton group copepod analyzed. It was observed that the copepod species richness was the highest in summer (20 species), followed by in autumn (14 species) and in spring (10 species). The copepod abundance peaked in spring, and was lower in summer and autumn. Mesocopepod species Centropages mcmurrichi dominated in spring, while smaller copepods such as Acartia pacifica, Calanopia thompsoni, and Paracalanus parvus dominated in summer and autumn. According to the investigation data from type Ⅰ net, the copepod community could be divided into two subgroups, i.e., low temperature group in spring and high temperature group in summer-autumn. The combination of the environmental factors including sea surface temperature, surface nitrate, surface silicate, and bottom silicate had the most significant effects on the copepod community structure in the Bay (r=0.836), and each of the four prominent variables was significantly negatively correlated with copepod abundance (P=0.05). Overall, the copepod community in Xiangshan Bay had a significant seasonal variation, and an inter-annual variation was observed in the seasonal pattern of copepod, as compared with historical data.
    Characteristics of plankton community and their relationships with environmental factors in mudflat wetland of Hangzhou Bay, East China.
    LI Gong-guo1,2, TU Xiao-xia1,2, WANG Pei-er1,2, WANG Zi-pan2, LIU Hatrieuhungmr3, YANG Ji-fang1,2**
    2013, 32(10):  2764-2771. 
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    A seasonal investigation was conducted on the plankton community structure at five sampling profiles (S1-S3 for discharge area and S4-S5 for non-discharge area) in the areas with high and medium tide levels of the mudflat wetland of Hangzhou Bay in April (spring), July (summer), October (autumn), 2010 and January (winter), 2011, aimed to understand the characteristics of the plankton community and their relationships with environmental factors. In the wetland, the annual average density of phytoplankton was 3278 ind·L-1, being dominated by Oscillatoria (69.2%) and Ulothrix (17.2%), and the biomass was 0.039 mg·L-1, being dominated by Coscinpdoscus (66.2%) and Nitzschia (23.5%). The annual average density of zooplankton was 54.4 ind·L-1, being dominated by Rotifera (68.1%) and Copepoda (29.5%), and the biomass was 0.268 mg·L-1, being dominated by Copepoda (61.2%) and Rotifera (23.9%). The dominant species of each group of plankton were Oscillatoria, Brachionus calyciflorus, Diaphanosoma brachyurum, Sinocalanus dorrii, and Nematodes, respectively. The water nutrient concentrations and the biomass of plankton community were much higher at the profiles S2-S3 than at the other profiles, and much higher in the areas with medium tide level than with high tide level. The water NH4+-N concentration was significantly linearly correlated with phytoplankton biomass and zooplankton biomass, and the pollution index had a significant positive correlation with rotifers biomass (P<0.001). The areas with medium tide level were seriously polluted by inland discharge, whereas the significant increase of rotifer biomass and the decline of zooplankton species richness were the important characteristics of the plankton community.
    Characteristics of phytoplankton community structure in typical reservoirs in Weihe River Basin of China.
    ZHOU Xiao-yuan**, ZHANG Xing-lang, HAN Ya-hui, WANG Mei, GAO Hong-wei
    2013, 32(10):  2772-2779. 
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    In June 2011, an investigation was conducted on the community structure of phytoplankton in four typical reservoirs in the Weihe River Basin. By using the β diversity index, non-metric multidimensional scaling (NMDS), and cluster analysis, the phytoplankton community structure in the four reservoirs was classified, and the causes resulting in the differences in the community structure were analyzed. A total of 40 species and 8 genera of phytoplankton in the four reservoirs were identified. The cell density of the phytoplankton ranged from 12.00×104 to 132.48×104 cells·L-1, and the biomass ranged from 0.39 to 3.29 mg·L-1. In terms of species composition, the phytoplankton in the four reservoirs belonged to diatomchlorella. The standing biomass of the phytoplankton in Shitouhe reservoir was mainly consisted of Bacillariophyta and Euglenophyta, and that in Xiluoyu reservoir was mainly of Euglenophyta and Chlorophyta. The composition of the phytoplankton in Taoqupo reservoir was more disperse, but the cell density was mainly consisted of Chlorophyta, Euglenophyta and Chrysophyta, whereas the biomass was mainly of Euglenophyta, Chrysophyta, and Pyrrophyta. The cell density of the phytoplankton in Xijiao reservoir was mainly consisted of Bacillariophyta and Cyanophyta, and the biomass was mainly of Bacillariophyta and Euglenophyta. The cell density and biomass of the phytoplankton in the four reservoirs was decreased in the order of Xijiao reservoir, Taoqupo reservoir, Xiluoyu reservoir, and Shitouhe reservoir. According to the β diversity index, NMDS, and cluster analysis, the phytoplankton community in Shitouhe and Xiluoyu reservoirs could be classified as a common group, while that in Taoqupo and Xijiao reservoirs could be classified as two other independent groups. The variations of the phytoplankton community structure among the four reservoirs could be primarily attributed to the differences in trophic levels. In addition, illumination and temperature could partly account for these variations.
     
    Ecosystem health assessment of alpine grassland wetland nature reserve. 
    WANG Wei1, CHANG Xue-li1**, LU Shi-hai2, SAI Bayaertu3, WUFER Tuohuti3, WU Qier4
    2013, 32(10):  2780-2787. 
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    Alpine grassland wetland is the most important water source region of arid area oasis. Its ecosystem health assessment is crucial for understanding the mechanisms of regional environmental change. The Bayanbulak National Alpine Grassland Nature Reserve in the central part of Tianshan Mountains is the representative alpine grassland wetland ecosystem in the arid area of Eurasia continent. In this paper, “3S” technology and ground reflective spectrumbiomass model were applied to analyze the 2002-2010 MODIS NDVI data, and the ecosystem health status of the Reserve was assessed from the viewpoint of productivity. In the Reserve, the ecosystem health was mainly affected by climate fluctuation. In the process of the ecosystem health changed from average level to the best, the health status of the ecosystem was generally good. The healthy and healthier areas accounted for more than 91% of the total area, and there was no significant difference among different divisions. In the process of ecosystem health changed from average level to the worst, the health status of the ecosystem was overall bad, and the healthy area was less than 40%. There was an obvious heterogeneity among different divisions. The health level of the core area (wetland) was lower than that in the experimental and buffer areas (alpine grassland). The core area (wetland) played an important role in animal husbandry production and biodiversity conservation. Even in the worst year, 48% of the wetland still had a higher productivity than the average level, and the healthier area accounted for more than 18%.
    Spatiotemporal variations of air pollution index in China’s megacities.
    REN Wan-xia1, XUE Bing1**, ZHANG Lin2, MA Zhi-xiao1,3, GENG Yong1
    2013, 32(10):  2788-2796. 
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    Urban air pollution has been one of the key environmental problems restricting China’s sustainable development. It is of significance to approach the spatiotemporal patterns of air pollution in megacities for the establishment of regional environmental management policies in China. Taking Beijing, Shanghai, Tianjin, and Chongqing as the study cases, and based on the database of air pollution index (API) from July 2000 to June 2012, a total of 4382 days, this paper analyzed the spatiotemporal variation characteristics and regional differentiation patterns of air quality in China’s megacities. During 2000-2012, the air quality in  Beijing, Shanghai, Tianjin, and Chongqing had been improved gradually, in which, the total days with the air quality over National grades I and II in 2011/12 increased by 60%, 9%, 112%, and 80%, respectively, as compared to those in 2000/01. However, in definite periods of time, there existed the rebound of air pollution, with a higher frequency of serious pollution. The daily average API in the four megacities had a distinct seasonal variation, with the pollution accumulation type of “V”. The PM10 had replaced SO2 into the primary air pollutant, indicating that the air pollution sources in the megacities were more and more complicated. Due to the synchronization trend in the seasonal variation of API among the megacities, urban air pollution had become a regional environmental problem. In the four megacities, the primary period of the daily API variation was around 300 days, and the secondary period was around 150 days. Except that in Chongqing, the API in Beijing, Shanghai, and Tianjin presented the ‘weekend effect’. It was suggested the urban API was dually affected by the natural and human elements.
    Spatiotemporal pattern of vegetation net primary productivity in Henan Province of China based on MOD17A3.
    WANG Xin-chuang, WANG Shi-dong, ZHANG He-bing**
    2013, 32(10):  2797-2805. 
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    By using the 2000-2010 annual net primary productivity (NPP) data from MOD17A3 dataset and the GIS technology, a quantitative analysis was made on the spatiotemporal variation of NPP in Henan Province of China. In the Province, the annual NPP ranged from 308 to 430 g C·m-2·a-1, with an average of 384 g C·m-2·a-1. The average annual NPP was higher in the south and lower in the north part of the Province. The area with high NPP (>500 g C·m-2·a-1) was mainly distributed in the forested regions of west and southeast Henan. The forested regions of Taihang Mountains and Danjiang River Basin had an annual NPP of 200-300 g C·m-2·a-1. The farmland regions had an average annual NPP of 300-500 g C·m-2·a-1, the ecological conservation zone of Yellow River had an average annual NPP of <200 g C·m-2·a-1, while the cities and their surrounding areas had an average annual NPP of <100 g C·m-2·a-1. As compared with that in 2000, the annual NPP in most parts of the Province in 2010 had an increase, and the areas with the increased annual NPP accounted for 93.8% of the territory of the Province. The increase of the annual NPP in the Province was mainly in linear, and the areas with an increment of >10% occupied 83.7% of the territory of the Province. The areas with a <-10% decrease of annual NPP were mainly distributed in Danjiang River Baisn, northern parts of Jiaozuo City and Jiyuan City, and the areas surrounding cities, which could be induced by the destruction of forests and the expansion of cities. The distribution of vegetation types and the differences in the mean annual temperature and mean annual precipitation in the Province led to the differences in the NPP distribution, i.e., lower in north and higher in south. There existed a great difference in the estimation of the NPP among different NPP estimation models or among different data sources.

     
    Climate change and its effects on climatic productivity in the ThreeRiver Headwaters Region in 1960-2011.
    GUO Pei-pei, YANG Dong, WANG Hui, CHENG Jun-qi**
    2013, 32(10):  2806-2814. 
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    Based on the air temperature and precipitation data from 13 meteorological stations in the ThreeRiver Headwaters (Yangtze River, Yellow River, and Lancang River) Region in 1960-2011, the climatic productivity in this Region was estimated by Thornthwaite Memorial model, and, through linear trend analysis, Kriging interpolation, MannKendall test, and Empirical Orthogonal Function (EOF) resolution, the spatiotemporal variations of the air temperature, precipitation, and climatic productivity were analyzed, with the responses of the climatic productivity to climate change studied. In this Region, the mean annual temperature and the mean temperature in winter and in summer in recent 52 years were featured by repeated cold and warm fluctuations, but overall, presented an obvious rising trend. The annual precipitation had no obvious variation trend, but the precipitation in winter and in growth season had an increasing trend. Spatially, the precipitation had opposite variation trend in the east and west as well as in the south and north. The climatic productivity had less increase before the 21st century, but increased obviously since then. The correlation coefficient of climatic productivity and air temperature was larger than that of climatic productivity and precipitation, illustrating that air temperature was the main factor limiting the climatic productivity. The warm and wet climate increased the climatic productivity by 8.67%, but the cold and dry climate decreased the climatic productivity by 8.91%. In the future, the region’s climate would generally be warm and wet, and thus, the climatic productivity would be increased, which would be conducive to the improvement of natural herbage yield.
    Basic theory and technical framework of coastal wetland landscape process model.
    LIU Hong-yu1**, LI Zhao-fu2
    2013, 32(10):  2815-2822. 
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    Landscape process model is a spatially explicit model which is processbased and able to fully reveal the mechanisms of the spatiotemporal dynamics of regional landscape pattern. The model concerns a series of ecological processes, can reveal the variations of the structure and function of definite region’s landscape system, and thus, is an important means for the regional landscape planning, assessment, and management. Wetland landscape process model is one of the hotspots of great concern in recent years. Coastal wetland landscape is affected by the ocean tides, and has highly complicated dynamic variations. It is needed to study these dynamic variations from the aspects of basic theory, key points of model construction, and the processes of the model construction, including (1) to understand the ecological elements (hydrology, soil, plant community, climate, and geomorphology, etc.) and their interactions of coastal wetland landscape, which is the basis for constructing processdriven landscape model, and to explore the spatial heterogeneity of these ecological elements and its effects on the ecosystem evolution, which is the key for determining the main variables of processdriven landscape model, (2) to solve the key issues for constructing landscape process model, including model structure, its appropriate spatial scale, model construction methods, and model calibration and application. The landscape process model should display space and process changes, and thus, should include several ecosystem models based on each “cell” and the horizontal fluxes of material and information between “cells”. The spatial scale of the model means the “cell” size, while the ways of the model construction are “bottom-up” and “topdown”, and (3) to integrate the ecosystem model with GIS computer system, which is the key for landscape process model construction. The technical framework described in this paper is aiming at coastal wetland landscape process, which also could have significance for the construction of landscape process models for other wetland types.
    Carriers for immobilized laccase: Research progress.
    WANG Xin**, LIU Li, LU Jia-liang, LIANG Ji-yan, CUI Li
    2013, 32(10):  2823-2829. 
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    Laccase is a kind of oxidases, which is easily obtained and featured with excellent characteristics. More and more attentions have being paid on laccase because of its widespread applications in the field of environmental pollution control. To immobilize the freestate laccase to improve its catalytic efficiency and reuse rate, the selection of carriers is crucial for the immobilization process. Easily obtained and appropriate carriers can simplify the immobilization process, being conducive to the industrialized production and application of immobilized laccase, while inappropriate carriers could directly impact the use efficiency of immobilized laccase. In recent years, with the rapid development of the researches in materials, environment, and other related areas, growing numbers of new and high quality materials have been made into the carriers of immobilized laccase. To a certain extent, these newly developed carriers can enhance the utilization rate of laccase. In addition, some already applied carries after improvement are reused for preparing the immobilized laccase, and make the functions of laccase somewhat improved. This paper introduces several newly developed materials used as the carriers for laccase immobilization, summarizes the functions of laccase after immobilization, defines the optimal conditions for laccase immobilization, enumerates the advantages and disadvantages of various carriers, and analyzes the development trend of the carriers for laccase immobilization.
    Forecast of Microtus fortis disaster in Dongting Lake region of China.
    XU Zheng-gang1,2, ZHAO Yun-lin3, LI Bo1, ZHANG Mei-wen1, WANG Yong1**
    2013, 32(10):  2830-2836. 
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    An investigation was conducted on the Microtus fortis disaster in the Dongting Lake region of China, aimed to effectively reduce the agricultural production loss caused by this vole. Since 2003, 8 typical sampling sites along the Lake were installed, and the investigation at each site was conducted at least once in each season for more than 3 years. There existed differences in the outbreak risk degree of the M. fortis at different sites, and the East Dongting Lake area was considered as the higher outbreak risk region. The M. fortis population had a singlepeak fluctuation within a year, and peaked in summer. The west bank of East Dongting Lake was the main emigrated area of M. fortis, while the east bank of the Lake was the main immigrated area of this vole, causing the occurrence of M. fortis disaster. There was a close correlation between the quantity and the infection degree of the immigrated M. fortis. Through the analysis on the occurrence patterns of M. fortis disaster at different sites, a corresponding forecast model was established, which could be helpful to the integrative management of M. fortis disaster.