Table of Content

18 January 2013, Volume 24 Issue 1

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Vertical  variability of Pinus sylvestris var. mongolica tree ring δ¹³C and its relationship with tree ring width in northern Daxing’an Mountains of Northeast China.

SHANG Zhi-yuan1, WANG Jian1, ZHANG Wen1,2, LI Yan-yan1, CUI Ming-xing3,4, CHEN Zhen-ju4, ZHAO Xing-yun5,6

2013, 24(1):  1-9. 

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A measurement was made on the vertical direction tree ring stable carbon isotope ratio (δ¹³C) and tree ring width of Pinus sylvestris var. mongolica in northern Daxing’an Mountains of Northeast China, with the relationship between the vertical direction variations of the tree ring δ¹³C and tree ring width analyzed. In the whole ring of xylem, earlywood (EW) and bark endodermis, the δ¹³C all exhibited an increasing trend from the top to the base at first, with the maximum at the bottom of tree crown, and then, decreased rapidly to the minimum downward. The EW and latewood (LW) had an increasing ratio of average tree ring width from the base to the top. The average annual sequence of the δ¹³C in vertical direction had an obvious reverse  correspondence  with the average annual sequence of tree ring width, and had a trend comparatively in line with the average annual sequence of the tree ring width ratio of EW to LW above tree crown. The variance analysis showed that there existed significant differences in the sequences of tree ring δ¹³C and ring width in vertical direction, and the magnitude of vertical  δ¹³C variability was basically the same as that of the interannual δ¹³C variability. The yeartoyear variation trend of the vertical  δ¹³C sequence was approximately identical. For each sample, the δ¹³C sequence at the same heights was negatively correlated with the ring width sequence, but the statistical significance differed with tree height.

Soil organic carbon storage in different aged Larix gmelinii plantations in Great Xing’an Mountains of Northeast China.

QI Guang1,2, WANG Qing-li1, WANG Xin-chuang1, YU Da-pao1, ZHOU Li1, ZHOU Wang-ming1, PENG Shun-lei2, DAI Li-min1

2013, 24(1):  10-16. 

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A sampling plot investigation was conducted to study the soil organic carbon (SOC) storage in 0-40 cm layer in 10-, 15-, 26- and 61 years old Larix gmelinii plantations in Great Xing’an Mountains of Northeast China as well as the temporal variation pattern of the SOC source/sink during the plantation management after the clear cutting of primary L. gmelinii forest. With the increasing age of the plantations, the SOC storage increased after an initial decrease, and the inflection point was at a stand age between 15- and 26-years old. Compared with that of primary forest, the SOC storage of the plantations played a role of carbon source at early stage (10-26 years old), but gradually transformed into carbon sink then, with a SOC storage of 158.91 t·hm^-2 in 61-year-old plantation. The SOC storage of the plantations increased with soil depth initially, but was higher in upper soil layer than in deeper soil layer after the stand age being 26, which implied that human disturbance had strong effects on the vertical distribution of SOC. It was considered that the appropriate cutting age for the L. gmelinii plantations in Great Xing’an Mountains could be at least 60 years old.

Effects of gap size on the spatial heterogeneity of soil water in Pinus koraiensisdominated broad-leaved mixed forest.

WANG Li-xia1, DUAN Wen-biao1, CHEN Li-xin1, DU Shan1, WEI Quan-shuai1, ZHAO Jian-hui1, ZHANG Chen2

2013, 24(1):  17-24. 

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In August-October 2011, the soil water content (SWC) at different depths in different sized gaps in Pinus koraiensisdominated broad-leaved mixed forest of Xiaoxing’an Mountains, Northeast China was continuously measured by grid nesting method and time domain reflectometry (TDR), and the spatial heterogeneity of the SWC was analyzed by the principles and approaches of geostatistics. The SWC was most abundant in medium gap, followed by in large gap and in small gap whereas the maximum difference of SWC was the biggest in large gap, followed by in medium gap, and in small gap. The variation range of the nugget of SWC at different depths in the large, medium, and small gaps was 0.001-0.404, 0.001-0.273, and 0.001-0.261, respectively. The SWC heterogeneity resulted from random part and the total system SWC spatial heterogeneity were decreased in the order of large gap > medium gap > small gap. The spatial distribution pattern of SWC was most complicated in medium gap, while the spatial dependence in the variation of the SWC pattern was the strongest in large gap. High-grade patches (SWC was 50%-60%) occupied the largest area in medium gap, followed by in large gap, and there was no highgrade patch in small gap. As for the SWC at same depths and in same months, its grade distribution was most simple in small gap, but relatively complicated in large and medium gaps. The maximum value of SWC increased with increasing gap size.

Root architecture of two desert plants in central Hexi Corridor of Northwest China.

SHAN Li-shan1, LI Yi1, REN Wei2, SU Shi-ping1, DONG Qiu-lian1, GENG Dong-mei1

2013, 24(1):  25-31. 

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In this study, the root systems of desert plant species Reaumuria soongorica and Nitraria tangutorum in the central Hexi Corridor of Northwest China were excavated by shovel, and the characteristics of the plant root architecture were analyzed by using topology and fractal theory. The root topological indices of the two desert plants were small, and the root branching patterns were herringbonelike. The roots of the two desert plants had obvious fractal characteristics, with the fractal dimension of R. soongorica and N. tangutorum being (1.18±0.04) and (1.36±0.06), respectively. The root fractal dimension and fractal abundance were significantly positively correlated with the root average link length. The root average link lengths of the two plants were long, which enlarged the plants’ effective nutrition space, and thus, made the plants adapt to the dry and infertile soil environment. The sums of the root crosssectional areas before and after the root bifurcation of the two desert plants were equal, which verified the principle of Leonardo da Vinci. A total of 17 parameters of root architecture were analyzed by the principal component analysis. The parameters of root topological structure, numbers of root links, stepwise branching ratio, and root diameter could well present the root architecture characteristics of the two desert plants.

Eco-physiological responses and related adjustment mechanisms of Artemisia ordosica and Caragana korshinskii under different configuration modes to precipitation variation.

ZHOU Hai-yan1, WANG Ying-jue2, FAN Fan3, FAN Heng-wen1

2013, 24(1):  32-40. 

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This paper studied the community characteristics of two sandfixing plants (Artemisia ordosica and Caragana korshinskii) under different configuration modes (1 m×1 m and 2 m×2 m) in the Shapotou region of Northwest China as well as the water relation, gas exchange, and their adjustment mechanisms of the plants under natural and artificial precipitation conditions. With the variation of soil water content, the physiological water consumption and growth characteristics of A. ordosica differed from those of C. korshinskii. A. ordosica presented obvious fluctuation in the stomatal conductance, water potential, transpiration rate, photosynthetic rate, and rapid growth, and had higher water consumption than C. korshinskii. However, the variations of the abovementioned indices of C. korshinskii were relatively slow and more constant. The C. korshinskii had a lower photosynthetic rate but a very high accumulated biomass over years than A. ordosica. The response procedures and adjustment mechanisms of the two plants under water stress differed, with a water-conserving mechanism for A. ordosica and a watersaving mechanism for C. korshinskii. In extremely drought years, the C. korshinskii had stronger capabilities of water-saving and stress tolerance than A. ordosica. It was suggested that the selection of sandfixing plants should have a view to the benefits in water saving and sand fixation, and also, to the stability of sand-fixing forest.

Effects of increased precipitation on the water use of Nitraira tangutorum at southeast edge of Baddain Jaran Desert in China.

ZHU Ya-juan, LU Qi, WU Bo, LI Yong-hua, YAO Bin, ZHANG Jin-xin

2013, 24(1):  41-48. 

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This paper studied the threshold value of the water use of Nitraria tanturorum shrubs at the southeast edge of Baddain Jiran Desert. From the early May to late September in 2009, an irrigation simulating increased precipitation was conducted once every month. Three ratios of increased precipitation (0, 50% and 100%) were designed, based on the local mean annual precipitation (115 mm). On the 1 day before irrigation and the 1, 3 and 7 days after irrigation in May, July and September, the δ_D in the xylem water of N. tangutorum,  the soil water at the depths 10 and 30 cm, and the  well water and natural rainfall, and the variations of the soil water content were measured. Under natural condition, the N. tangutorum mainly utilize ground water in May and September, and utilize the soil water at the depths 10 and 30 cm in July. After irrigation, the ground water use rate of the N. tangutorum decreased, while the soil water use rate increased. In the treatment of 100% increased precipitation, the δ_D ratio of the water in N. tangutorum xylem was affected significantly, and the water use of the N. tangutorum in May, July and September increased. In the treatment of 50% increased precipitation, the soil water condition in May and July was improved, but the water use rate had little improvement. Only when the increased precipitation reached 100% of the local mean annual precipitation, could the water use rate of the N. tangutorum have an obvious increase.

Seasonal differences in the leaf hydraulic conductance of mature Acacia mangium in response to its leaf water use and photosynthesis.

ZHAO Ping, SUN Gu-chou, NI Guang-yan, ZENG Xiao-ping

2013, 24(1):  49-56. 

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In this study, measurements were made on the leaf water potential (Ψ_l), stomatal conductance (g_s), transpiration rate, leaf area index, and sapwood area of mature Acacia mangium, aimed to understand the relationships of the leaf hydraulic conductance (K_l) with the leaf water use and photosynthetic characteristics of the A. mangium in wet season (May) and dry season (November). The ratio of sapwood area to leaf area (A_sp/A_cl) of the larger trees with an average height of 20 m and a diameter at breast height (DBH) of 0.26 m was 8.5% higher than that of the smaller trees with an average height of 14.5 m and a DBH of 0.19 m, suggesting that the larger trees had a higher water flux in their leaf xylem, which facilitated the water use of canopy leaf. The analysis on the vulnerability curve of the xylem showed that when the K_l  decreased by 50%, the Ψ_l in wet season and dry season was -1.41  and -1.55 MPa, respectively, and the vulnerability of the xylem cavitation was higher in dry season than in wet season. The K_l peak value in wet season and dry season was 5.5 and 4.5 mmol·m^-2·s-¹·MPa^-1, and the maximum transpiration rate (T_{r max}) was 3.6 and 1.8 mmol·m^-2·s^-1, respectively. Both the K_l and  T_{r max}  were obviously higher in wet season than in dry season. Within a day, the K_l and T_r fluctuated many times, reflecting the reciprocated cycle of the xylem cavitation and refilling. The leaf stomatal closure occurred when the K_l declined over 50% or the Ψ_l reached -1.6 MPa. The g_s would be maintained at a high level till the K_l declined over 50%. The correlation between the hydraulic conductance and photosynthetic rate was more significant in dry season than in wet season. The loss of leaf hydraulic conductance induced by seasonal change could be the causes of the decrease of T_r and CO₂ gas exchange.

Influence of shading during the processes of drought stress and re-watering on the physiological and biochemical characteristics of Haplocladium microphyllum.

CHEN Wen-jia1, ZHANG Nan2, HANG Lu-lu1, WANG Yuan1, JI Meng-cheng1

2013, 24(1):  57-62. 

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An artificial water control experiment was conducted to study the influence of shading on the membrane permeability, osmoregulation capability, and protective enzyme activities of Haplocladium microphyllum during the processes of drought stress and re-watering. Four treatments of shading were installed, i.e., full daylight and 30%, 50% and 70% of shading. During drought stress, the relative water content of H. microphyllum presented a decreasing trend, while the relative conductivity reached the maximum when the drought stress lasted for 21 days, and the conductivity was high up to 58.0% under full daylight. The soluble sugar and free proline contents and the SOD and POD activities of the plant under drought stress were decreased after a sustained increase. During rewatering, the relative water content of H. microphyllum showed an increasing trend, the relative conductivity, soluble sugar and free proline contents, and SOD and POD activities had a slight increase first and decreased gradually then, but the SOD and POD still kept high activities. After rewatering, most of the test indices recovered to the levels before the drought stress. It was suggested that H. microphyllum had the typical characteristics of resurrection plants, possessing a strong capability against drought during the variation of soil moisture content.

Relationships between grazingpath and Berberis aggregate population characteristics in upper reaches of Minjiang River, Southwest China.

LIU Jin-xin, GONG Yuan-bo, ZHENG Jiang-kun, ZHANG Xing-hua, JIANG Guang-zheng, YUE Yan-jie, ZUO Qin, LIU Mu

2013, 24(1):  63-70. 

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Taking the Berberis aggregate shrubs in the ecotone of dry valley and montane forests in upper reaches of Minjiang River as study objects, and by the methods of tracking grazing and field survey, this paper studied the characteristics of habitat utilization by livestock and the features of grazing-path. The major factors affecting the features of grazing-path were screened by redundancy analysis (RDA), and the relationships of the grazing-path features with the coverage, size class, and distribution pattern of the shrubs were analyzed. It was shown that the distribution pattern of the grazing-path could intuitively reflect the characteristics of the habitat utilization by livestock, being in accordance with the results of tracking grazing. The Morisita index at 5 m scale could objectively reflect the distribution type of the grazing-path. Sample plots 1, 2 and 6 presented a contagious distribution of grazing-path, while the other plots showed regular distribution. In slope scale, the coverage and height of the shrubs were the notable affecting factors, which had negative correlations with the grazing-path features. There was a significant negative correlation between the coverage of B. aggregate population and the area of grazing-path. The population structure of B. aggregate had a close correlation with the distribution of grazing-path. The ratio of the long axis to short axis of the shrubs was averagely 1.29, and the shape of the shrubs approached to round. It was considered that the grazingpath landscape and the livestock on the grazingpaths had the function of reconstructing the shape of the shrubs. The directionality of the population pattern of B. aggregate was generally in line with the distribution type of grazing-path, but actually, they were opposite in distribution. The patches of the shrubs were in aggregated or uniform distribution in the areas deviated from the grazing-path.

 

Photosynthetic characteristics of an invasive plant Conyza canadensis and its associated plants.

WANG Xiao-hong1，2, JI Ming-shan1

2013, 24(1):  71-77. 

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To explore the invasion mechanisms of Conyza canadensis and develop effective control measures, this paper studied the photosynthetic characteristics of the invasive plant and its main associated plants Ixeris chinensis and Commelina communis. The light saturation point and light compensation point of C. canadensis were 1634.00 and 23.84 μmol·m^-2·s^-1, respectively, which were between those of the two associated plants. The maximum net photosynthetic rate of C. canadensis below light saturation point was 28.12 μmol·m^-2·s^-1, being much higher than that of the two associated plants. The apparent quantum yield of C. canadensis was 0.06, equal to that of I. chinensis  but higher than that of C. communis. The CO₂ saturation point and CO₂ compensation point of C. canadensis were 834.00 and 23.69 μmol·mol^-1, respectively. The maximum net photosynthetic rate of C. canadensis below CO₂ saturation point  was 31.97 μmol·m^-2·s^-1, which was between that of the two associated species. The carboxylation efficiency of C. canadensis was 0.078, being higher than that of the two associated species. The variations of photosynthetically active radiation and CO₂ concentration had little effects on the stomatal conductance and transpiration rate of the three plants, but significantly affected their water use efficiency. C. canadensis had higher photosynthetic rate and material accumulation capability, and its high productivity could be one of the important factors for its successful invasion.

Effects of exogenous iron on lead accumulation in Typha latifolia from a lead-contaminated soil.

ZHONG Shun-qing1, XU Jian-ming2，3

2013, 24(1):  78-82. 

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A pot experiment was conducted to study the effects of adding 100 and 500 mg·kg^-1 of exogenous iron (Fe) on the lead (Pb) accumulation in Typha latifolia growing on a soil with 0, 100, 500 and 1000 mg·kg^-1 of Pb, respectively. In treatment 500 mg Fe·kg^-1, the Pb concentration in T. latifolia shoots and roots was higher,  compared with that in treatment 100 mg Fe·kg^-1. When the soil Pb concentration was 1000 mg·kg^-1, the Pb concentration in T. latifolia shoots and roots in treatment 500 mg Fe·kg^-1  increased by 33.7% and 50.5%, respectively,  compared with that in treatment 100 mg Fe·kg^-1. The exchangeable Pb concentration in rhizosphere soil was 77.0%-114.6% higher in treatment 500 mg Fe·kg^-1 than in treatment 100 mg Fe·kg^-1. When the soil Pb concentration was 0, 100 and 1000 mg·kg^-1, the root dry mass in treatment 500 mg Fe·kg^-1 had a significant decrease,  compared with that in treatment 100 mg Fe·kg^-1. It was suggested that adding appropriate amount of Fe to Pb contaminated wetland soil could increase the availability of soil Pb and improve the Pb accumulation in plants.

Effects of aquatic plants during their decay and decomposition on water quality.

TANG Jin-yan, CAO Pei-pei, XU Chi, LIU Mao-song

2013, 24(1):  83-89. 

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Taking 6 aquatic plant species as test objects, a 64-day decomposition experiment was conducted to study the temporal variation patterns of nutrient concentration in water body during the process of the aquatic plant  decomposition. There existed greater differences in the  decomposition rates between the 6 species. Floating-leaved plants had the highest decomposition rate, followed by submerged plants, and emerged plants. The effects of the aquatic plant species during their  decomposition on water quality differed, which was related to the plant biomass density. During the  decomposition of Phragmites australis, water body had the lowest concentrations of chemical oxygen demand, total nitrogen, and total phosphorus. In the late decomposition period of Zizania latifolia, the concentrations of water body chemical oxygen demand and total nitrogen increased, resulting in the deterioration of water quality. In the  decomposition processes of Nymphoides peltatum and Nelumbo nucifera, the concentrations of water body chemical oxygen demand and total nitrogen were higher than those during the decomposition of other test plants. In contrast, during the  decomposition of Potamogeton crispus and Myriophyllum verticillatum, water body had the highest concentrations of ammonium, nitrate, and total phosphorus. For a given plant species, the main water quality indices had the similar variation trends under different biomass densities. It was suggested that the existence of moderate plant residues could effectively promote the nitrogen and phosphorus cycles in water body, reduce its nitrate concentration to some extent, and decrease the water body nitrogen load.

Relationships between vegetation characteristics and soil properties at different restoration stages on slope land with purple soils in Hengyang of Hunan Province, South-central China.

YANG Ning1,2, ZOU Dong-sheng2, YANG Man-yuan3, HU Li-zhen1, ZOU Fang-ping1, SONG Guang-tao1, LIN Zhong-gui1

2013, 24(1):  90-96. 

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By using space series to replace time series, this paper studied the relationships between the vegetation characteristics and soil properties at different restoration stages on the slope land with purple soils in Hengyang of Hunnan Province South-central China. There existed obvious differences in the soil physical and chemical properties at different restoration stages. From grassplot, grass-shrub, shrub to shrub-arbor, the soil organic matter, total and available N, and moisture contents increased markedly, soil bulk density had an obvious decrease, soil total and available P contents changed little, and soil pH decreased gradually, but no significant differences were observed among different restoration stages. At different restoration stages, the biomass of plant community had effects on the quantity and composition of soil microbes. The quantities of soil bacteria and fungi had significant positive correlations with the aboveground biomass of plant community, but the quantity of soil actinomycetes had less correlation with plant community’s aboveground biomass. At different restoration stages, the activities of soil urease, protease, alkaline phosphatase, invertase, cellulase, catalase, and polyphenol oxidase decreased with increasing soil layer, and had significant positive correlations with plant community’s richness and aboveground biomass.

Changes of nitrogen fractions in horse dung during its decomposition on the typical steppe of Inner Mongolia, North China.

CHEN Hai-yan1, Arengaowa2, LIU Xin-min2

2013, 24(1):  97-104. 

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From June 2008 to September 2009, a field experiment was conducted to study the change characteristics of the nitrogen fractions in horse dung during its decomposition on the typical steppe of Inner Mongolia. Two treatments were installed, i.e., deposited the horse dung on the ground and buried the horse dung in soil. In the two treatments, the concentrations of ammonia nitrogen (NH₃-N), amino acid nitrogen (AAN), and aminosugar nitrogen (ASN) in residual horse dung were maintained at a higher level in the earlier period of horse dung decomposition (0-90 d), but declined obviously in the later period (330-450 d). The concentrations of acid-hydrolysable unknown nitrogen (AHUN) and nonacidhydrolysable unknown nitrogen (UUN) presented an increasing trend with the decomposition of horse dung, and increased to a higher level in the later period. In fresh horse dung, NH₄⁺-N was the main fraction of inorganic nitrogen, and its concentration in residual horse dung decreased with the decomposition of horse dung. The concentration of NO₃^--N in fresh horse dung was lower, its leaching loss from the residual horse dung was weak, and it was accumulated in the residual horse dung with the decomposition of horse dung. The horse dung buried in soil had significant effects on the gaseous ammonia volatilization of NH₄⁺-N, but minor effects on the other nitrogen fractions. The main nitrogen sources of nitrogen mineralization in the earlier period of horse dung decomposition were NH₃^--N, AAN and ASN, and those in the later period were AHUN and UUN. The bioavailability of NH₄⁺-N was mainly revealed in the earlier period of horse dung decomposition, while that of NO₃^--N was in the later period.

Effects of biological soil crust on soil erodibility in Hilly Loess Plateau Region of Northwest China.

GAO Li-qian1,2,3, ZHAO Yun-ge1,2, QIN Ning-qiang1, ZHANG Guo-xiu1

2013, 24(1):  105-112. 

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Based on the analysis of the effects of biological soil crust (biocrust) in re-vegetated grasslands on soil physical and chemical properties, and by using EPIC estimation model in combining with simulated rainfall trials, this paper studied the effects of biocrust with different biomass and different soil texture on the soil erodibility (K  value) in Hilly Loess Plateau Region of Northwest China in different seasons. The results showed biocrust could significantly decrease soil erodibility, with the K  value of biocrust soil decreased by about 17%,  compared with subsoil. The soil erodibility decreased with the increasing biomass of biocrust. The K  value of moss crust soil  decreased by 21%,  compared with cyanobacteria crust soil. The erodibiliy of biocrust soil differed with different seasons, being significantly higher in rainy season than before or after the rainy season due to the differences in the biological activity of the biocrust organisms. The erodibilty of biocrust soil with different texture also varied significantly, with the K  value in the order of sandy loam soil > silt soil > sandy soil. The measurement under simulated rainfall showed that the development of biocrust could decrease the erodibility of biocrust soil by about 90%,  compared with that of the subsoil (5-10 cm).

Mechanisms of grass in slope erosion control in loess sandy soil region of Northwest China.

ZHAO Chun-hong1, GAO Jian-en1,2,3, XU Zhen3

2013, 24(1):  113-121. 

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By adopting the method of simulated precipitation and from the viewpoint of slope hydrodynamics, in combining with the analysis of soil resistance to erosion, a quantitative study was made on the mechanisms of grass in controlling the slope erosion in the cross area of windwater erosion in Loess Plateau of Northwest China under different combinations of rainfall intensity and slope gradient, aimed to provide basis to reveal the mechanisms of vegetation in controlling soil erosion and to select appropriate vegetation for the soil and water conservation in Loess Plateau. The grass Astragalus adsurgens with the coverage about 40% could effectively control the slope erosion. This grass had an efficiency of more than 70% in reducing sediment, and the grass root had a greater effect than grass canopy. On bare slope and on the slopes with the grass plant or only the grass root playing effect, there existed a functional relation between the flow velocity on the slopes and the rainfall intensity and slope gradient (V=DJ^0.33#em/em#^0.5, where V is flow velocity, D is the comprehensive coefficient which varies with different underlying surfaces, i is rainfall intensity, and J is slope gradient). Both the grass root and the grass canopy could markedly decrease the flow velocity on the slopes, and increase the slope resistance, but the effect of grass root in decreasing flow velocity was greater while the effect in increasing resistance was smaller than that of grass canopy. The effect of grass root in increasing slope resistance was mainly achieved by increasing the sediment grain resistance, while the effect of canopy was mainly achieved by increasing the slope form resistance and wave resistance. The evaluation of the soil resistance to erosion by using a conceptual model of sediment generation by overland flow indicated that the critical shear stress value of bare slope and of the slopes with the grass plant or only the grass root playing effect was 0.533, 1.672 and 0.925 Pa, respectively.

Composition and stability of soil aggregates in hedgerow-crop slope land.

PU Yu-lin1,2,3, LIN Chao-wen4, XIE De-ti1,3, WEI Chao-fu1,3， NI Jiu-pai1，3

2013, 24(1):  122-128. 

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Based on a long-term experiment of using hedgerow to control soil and water loss, this paper studied the composition and stability of soil aggregates in a hedgerow-crop slope land. Compared with those under routine contour cropping, the contents of >0.25 mm soil mechanical-stable and water-stable aggregates under the complex mode hedgerowcrop increased significantly by 13.3%-16.1% and 37.8%-55.6%, respectively. Under the complex mode, the contents of >0.25 mm soil water-stable aggregates on each slope position increased obviously, and the status of >0.25 mm soil wate-stable aggregates being relatively rich at low slope and poor at top slope was improved. Planting hedgerow could significantly increase the mean mass diameter and geometric mean diameter of soil aggregates, decrease the fractal dimension of soil aggregates and the destruction rate of >0.25 mm soil aggregates, and thus, increase the stability and erosion-resistance of soil aggregates in slope cropland. No significant effects of slope and hedgerow types were observed on the composition, stability and distribution of soil aggregates.

Effects of exogenous proline on the growth of wheat seedlings under cadmium stress.

SONG Min, XU Wen-jing, PENG Xiang-yong, KONG Fan-hua

2013, 24(1):  129-134. 

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Taking high protein wheat variety ‘Beinong 9549’ as test material, this paper studied the effects of foliagespraying different concentration (0, 1.0, 5.0 and 10.0 mmol·L^-1) proline on the growth and heavy metal uptake of wheat seedlings under cadmium stress. Under the stress of 1.0 mmol·L^-1 of CdCl₂, the root length, plant height and dry mass, leaf chlorophyll a and b and carotenoid contents of the seedlings decreased significantly by 24.0%, 15.0%, 27.5%, 23.3%, 6.7% and 30.8%, respectively, the leaf superoxide dismutase (SOD) activity decreased by 18.4%, the leaf proline, ascorbic acid and malondialdehyde (MDA) contents and the membrane permeability increased significantly by 78.6%, 31.5%, 17.9% and 24.8%, respectively, the leaf peroxidase (POD) activity was 2.4 folds higher, and the Cu uptake was promoted while the Zu absorption was inhibited, compared with the control. With the increasing concentration of sprayed proline, the root length, plant height and dry mass, and leaf chlorophyll a and b and carotenoid contents increased gradually to the levels of the control, the leaf proline and ascorbic acid contents and the leaf SOD activity increased, the leaf soluble protein content decreased after an initial increase, the leaf POD activity, MDA content and membrane permeability decreased, and the Zn accumulation increased while the Cd and Cu accumulation decreased. In sum, foliage-spraying proline could alleviate the cadmium stress on the growth of wheat seedlings, and spraying 5.0-10.0 mmol·L^-1 of proline could obtain the best effect.

Effects of arbuscular mycorrhizal fungus on the seedling growth of grafted watermelon and the defensive enzyme activities in the seedling roots.

CHEN Ke1,2, SUN Ji-qing1,2, LIU Run-jin1, LI Min1,2

2013, 24(1):  135-141. 

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A greenhouse pot experiment was conducted to study the effects of arbuscular mycorrhizal fungus Glomus versiforme on the seedling growth and root membrane permeability, malondiadehyde (MDA) content, and defensive enzyme activities of non-grafted and grafted watermelon growing on the continuously cropped soil. Inoculation with G. versiforme increased the seedling biomass and root activity significantly, and decreased the root membrane permeability and MDA content. The seedling shoot fresh mass, shoot dry mass, and root activity of non-grafted watermelon increased by 57.6%, 60.0% and 142.1%, and those of grafted watermelon increased by 26.7%, 28.0% and 11.0%, respectively,  compared with no G. versiforme inoculation. The root membrane permeability of non-grafted seedlings (C), grafted seedlings (G), nongrafted seedlings inoculated with G. versiforme (C+M), and grafted seedlings inoculated with G. versiforme (G+M) was in the order of C>G>C+M>G+M, and the root MDA content was in the sequence of C>G>G+M>C+M. G. versiforme inoculation increased the root phenylalanine ammonialyase (PAL), catalase (CAT), peroxidase (POD), β-1,3-glucanase and chitinase activities of grafted and non-grafted seedlings significantly, and the peaks of the POD, PAL and β-1,3-glucanase activities in the mycorrhizal roots appeared about two weeks earlier than those in the non-inoculated roots. These results indicated that inoculating arbuscular mycorrhizal fungus G. versiforme could activate the defensive enzyme activities of nongrafted and grafted watermelon seedlings, enable the seedling roots to produce rapid response to adversity, and thus, improve the capability of watermelon seedling against continuous cropping obstacle.

Identification of two Fusarium- isolates and their crude toxin allelopathic effect on Cucumis melo seedlings.

ZHAO Juan1, XUE Quan-hong2, DU Jun-zhi3, CHEN Jiao-jiao2

2013, 24(1):  142-148. 

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Eight fungi isolates were obtained from Fusarium-infected Cucumis melo (melon) plants and their rhizosphere soils. Taking melon cultivar ‘Xitian 1’ as test material, the reinoculation and seed germination experiments were conducted to investigate the pathogenicity and growth inhibition effect of these fungi isolates on melon. Through the determination of the induced enzyme activities, resistant substance contents, and cell membrane permeability of potted melon roots, the allelopathic effect of the crude toxins of two harmful fungi was studied, and according to the morphological characteristics and Internal Transcribed Spacer (ITS) sequencing, the two harmful fungi were identified. The crude toxins of the two harmful fungi TF and HF had strong inhibition effects on the germination and growth of the melon seeds. The MDA and soluble protein contents and the cell membrane permeability of the  ‘Xitian 1’ seedlings roots all increased, among which, the MDA content and cell membrane permeability  increased by 108.6% and 40.6%, respectively when treated with the stock solution of TF toxin,  compared with the control. The crude toxins of the two harmful fungi improved the induced enzyme activities of the melon roots, with the increment of the PAL and POD activities under the treatment of 10-fold dilution of TF crude toxin increased by 25.6% and 23.2%, respectively. When treated with the stock solution of HF toxin, the PAL activity  significantly increased by 30.0%. The two harmful fungi TF and HF were primarily identified as Fusarium equisti and F. proliferatum, respectively. This study showed that the two Fusarium -isolates could not infect melon via re-inoculation, but could negatively affect the melon’s normal growth and normal physiological and biochemical metabolism via toxins excretion, and in the meantime, improve the root protective enzyme activities, with the effects of both benefit and harmfulness on melon plants. The allelopathic hazard of the crude toxins of the isolates could be one of the main causes of continuous cropping obstacle of melon.

Screening and identification of low temperature-adapted antagonistic Bacillus isolated from Kekexili region of West China and the analysis of the isolates lipopeptide compounds.

XIE Yong-li1,2, GAO Xue-wen2

2013, 24(1):  149-155. 

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The research and exploitation of special microbial resources in extreme environment is of scientific significance and has broad applied prospect. In this paper, eight Bacillus strains isolated from the vegetation rhizospheres in Kekexili extreme region of Qinghai Province and presented good growth status at low temperature 4 and 10 ℃ were identified. Through physiological and biochemical analysis,
rep-PCR fingerprinting, and 16S rDNA and gyrB partial sequence analyses, the eight strains were identified as Bacillus mojavensis (3 isolates), Bacillus amyloliquefaciens (1 isolate), and Bacillus simplex (4 isolates). The agar plate antagonistic test showed that four of the isolates presented distinct antagonistic activity to Sclerotinia sclerotiorum and Xanthomonas oryzae pv. oryzae. The MALDI-TOF-MS analysis showed that the strain KKD-1 (B. mojavensis) produced fengycin and surfactin, whereas the strain KKD-2 (B. amyloliquefaciens) produced iturin A, surfactin and fengycin, suggesting that the biocontrol efficacy of the Bacillus strains could be related to the synthesis and excretion of the antifungal lipopeptide compounds. This study provided the bacterial resources for the research and exploitation of low temperatureadapted Bacillus biofertilizers and bio-pesticides.

Effects of climate and grazing on the vegetation cover change in Xilinguole League of Inner Mongolia, North China.

WANG Hai-mei1,2, LI Zheng-hai2, WANG Zhen3

2013, 24(1):  156-160. 

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Based on the monthly temperature and precipitation data of 15 meteorological stations and the statistical data of livestock density in Xilinguole League in 1981-2007, and by using ArcGIS, this paper analyzed the spatial distribution of the climate aridity and livestock density in the League, and in combining with the tenday data of the normalized difference vegetation index (NDVI) in 1981-2007, the driving factors of the vegetation cover change in the League were discussed. In the study period, there was a satisfactory linear regression relationship between the climate aridity and the vegetation coverage. The NDVI and the livestock density had a favorable binomial regression relationship. With the increase of NDVI, the livestock density increased first and decreased then. The vegetation coverage had a complex linear relationship with livestock density and climate aridity. The NDVI had a positive correlation with climate aridity, but a negative correlation with livestock density.  Compared with livestock density, climate aridity had far greater effects on the NDVI.

Natural succession of vegetation in Tiantong National Forest Park, Zhejiang Province of East China: A simulation study.

LU Na1,2, NI Jian1,2,3

2013, 24(1):  161-169. 

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By using spatially explicit landscape model (LANDIS 6.0 PRO), and parameterized this model with the long-term research and observation data of Tiantong National Station of Forest Ecosystem Observation and Research, this paper simulated the natural succession of evergreen broad-leaved forest in Tiantong National Forest park, Zhejiang Province in the future 500 years, analyzed the spatial distribution and age structure of dominant species and major landscapes, and explored the succession pattern of the evergreen broadleaved forest. In the park, the species alternation mostly occurred before the stage of evergreen broad-leaved forest. Pinus massoniana, Quercus fabric, and Liquidambar formosana occupied a large proportion during the early succession, but gradually disappeared with the succession process. Schima superba and Castanopsis fargesii took the main advantage in late succession, and developed to the climax community. Under the conditions without disturbances, the community was mainly composed of young forests in the early succession, and of mature or over-mature forests in the late succession, implying the insufficient regeneration ability of the community. LANDIS model could be used for simulating the landscape dynamics of evergreen broad-leaved forest in eastern China. In the future research, both the model structure and the model parameters should be improved, according to the complexity and diversity of subtropical evergreen broad-leaved forest.

Wetlands of priority restoration in Northeast China based on spatial analysis.

DONG Zhang-yu1,2, LIU Dian-wei1, WANG Zong-ming1, REN Chun-ying1, TANG Xu-guang1,2, JIA Ming-ming1,2, WANG Yan3

2013, 24(1):  170-176. 

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By using GIS/RS technology, and from the aspects of landscape structure, river and road densities, wetness index, geomorphology, and cultivated land productivity, a spatial analysis was made on the potentiality of wetland restoration in Northeast China, with the regions of priority and secondary priority restoration wetlands determined. Then, by using the coordinated development index of crop production and wetland as well as the landscape indices, the wetland restoration effect was verified. In Northeast China, the wetland area of priority restoration was 1.78×10⁶ hm², among which, farmland and grassland were the main types for restoration, accounting for 96.7% of the total, and mainly located in the Sanjiang Plain in the northeastern part and the Songnen Plain in the central part of Northeast China. The wetland area of secondary priority restoration was 1.03×10⁶ hm². After the restoration of the wetlands, the wetland area in Northeast China would be increased by 37.4%,  compared with the present wetland area, and the value of the coordinated development index of crop production and wetland would  increase from 0.539 before restoration to 0.733 after restoration. The landscape pattern would be more benefit to the performance of the ecological functions of the wetlands. This study revealed that the restoration scheme of the wetlands in Northeast China based on spatial analysis was practicable, which could provide data support for the implement of wetland restoration and the improvement of ecological environment in Northeast China.

Inversion of vegetation canopy’s chlorophyll content based on airborne hyperspectral image.

LI Ming-ze, ZHAO Xiao-hong, LIU Yue, LU Wei, DONG Shuai, MENG Lu

2013, 24(1):  177-182. 

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By using the airborne hyperspectral remote sensing data of Liangshui National Nature Reserve in Yichun of Heilongjiang Province, Northeast China, 15 spectral parameters including red edge area, triangular vegetation index, and normalized difference vegetation index, etc. were extracted， and in combining with 5 geographical parameters including slope, aspect, elevation, canopy density and total vegetation coverage, and by using SPAD-502, the vegetation canopy’s relative chlorophyll content in the reserve were measured, with the correlations of the leaf spectral reflectivity, its firstorder derivative and other deformations with the SPAD value analyzed. A prediction model for relative chlorophyll content was established by adopting the kernelbased partial least-squares regression, and a quantitative estimation of the vegetation canopy’s relative chlorophyll content in the study area was carried out with the established model. The results showed that the model performed best when the sections were three and the principle components were ten. The coefficient of determination of the model was R² = 0.855, the mean absolute percent error was 9.6%, and the prediction precision was 89.7%.

Spatiotemporal variation of water source supply service in Three Rivers Source Area of China based on InVEST model.

PAN Tao, WU Shao-hong, DAI Er-fu, LIU Yu-jie

2013, 24(1):  183-189. 

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The Three Rivers Source Area is the largest ecological function region of water source supply and conservation in China. As affected by a variety of driving factors, the ecosystems in this region are seriously degraded, giving definite impacts on the water source supply service. This paper approached the variation patterns of precipitation and runoff coefficient from 1981 to 2010, quantitatively estimated the water source supply of the ecosystems in the region from 1980 to 2005
 based on InVEST model, and analyzed the spatiotemporal variation pattern and its causes of the water source supply in different periods. In 1981-2010, the precipitation in the Three Rivers Source Area had a trend of increase after an initial decrease, while the precipitation runoff coefficient presented an obvious decreasing trend, suggesting a reduced capability of runoff water source supply of this region. The potential evapotranspiration had a declining trend, but not obvious, with a rate of -0.226 mm·a^-1. In 1980-2005, the water source supply of the region represented an overall decreasing trend, which was most obvious in the Yellow River Source Area. The spatiotemporal variation of the water source supply in the Three Rivers Source Area was the results of the combined effects of climate and land use change, and the climate factors affected the water source supply mainly through affecting the precipitation and potential evapotranspiration. Climate and land use change induced the ecosystem degradation and underlying surface change, which could be the main driving forces of the declined water source supply in the Three Rivers Source Area.

Geographical populations of brown planthopper in Nanning of South China and in Vietnam: A comparative study.

CHEN Yan1, WU Bi-qiu2, HUANG Suo-sheng2, HUANG Feng-kuan2, LING Yan2, LONG Li-ping2,3

2013, 24(1):  190-196. 

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A comparison was made on the differences of the geographical populations of brown planthopper (BPH), Nilaparvata lugens (St-l), collected from Nanning of South China and from Ha Noi, Ha Tinh, Hue, TP. Ho Chi Minh, and Song Cuu Long of Vietnam. The BPH populations from Nanning, Ha Noi, Ha Tinh and Hue could damage the rice varieties with Bph1 and bph2 genes, whereas the BPH populations from TP. Ho Chi Minh and Song Cuu Long showed stronger virulence to the rice varieties with Bph1, bph2, Bph3 and bph4 genes than the other populations. The survival rates of the nymphs from Nanning, Ha Noi, Ha Tinh and Hue populations on the rice varieties TN1, Mudgo and ASD7 were all above 52%, but those on the rice varieties Rathu Heenati, Babawee and Ptb33 were below 44%. The nymphs of the BPH populations from TP. Ho Chi Minh and Song Cuu Long on the TN1, Mudgo, ASD7, Babawee and Ptb33 had a survival rate of above 50%, but those on Rathu Heenati had a survival rate of below 50%. The nymphal development durations of the BPH populations from Nanning, Ha Noi and Hue were significantly shorter on TN1, Mudgo and ASD7 than on Rathu Heenati, Babawee and Ptb33, but for the BPH population from Ha Tinh, the nymphal development duration on TN1, Mudgo and ASD7, and on Rathu Heenati and Ptb33 had no significant difference. The nymphal development durations of the BPH population from TP. Ho Chi Minh on TN1 and ASD7 were significantly shorter than those on Rathu Heenati, Babawee and Ptb33, but for the BPH population from Song Cuu Long, the nymphal development durations on TN1, Mudgo, ASD7, Rathu Heenati, Babawee and Ptb33 had no significant difference.  After infested for 192 h, the nymph density of the BPH populations from Nanning and Ha Noi was significantly lower on Rathu Heenati, Babawee and Ptb33 than on TN1, Mudgo and ASD7, that of the BPH populations from Ha Tinh was significantly lower on Babawee than on TN1, Mudgo, the BPH populations from Hue and TP. Ho Chi Minh had a significantly lower nymph density on Babawee than on TN1, Mudgo, ASD7 and Rathu Heenati, and the BPH population from Song Cuu Long had a significantly lower nymph density on Babawee and Ptb33 than on TN1 and ASD7. The virulence of the BPH population from Nanning was similar with that of the BPH populations from central and northern Vietnam, which was a new proof that the BPH in South China was migrated from the central and northern parts of Vietnam.

Lethal effects of scopoletin and bisdemethoxycurcumin against Tetranychus cinnabarinus Boisd. (Acari: Tetranychidae): A simulation study.

YANG Zhen-guo, ZHANG Yong-qiang, DING Wei, LUO Jin-xiang

2013, 24(1):  197-204. 

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By using slide-dip bioassay method under laboratory condition, an investigation was made on the lethal effects of scopoletin, bisdemethoxycurcumin (BDMC), and their combination at an optimal mass ratio (7:6) of scopoletin to BDMC against the adult females of Tetranychus cinnabarinus Boisd. A timedose mortality model (TDM) was established, which passed the HosmerLemeshow test. The sensitivity of the adult females to the concentration change of the acaricides was in the sequence of scopoletin > optimal mass ratio of scopoletin to BDMC > BDMC. The peak mortality of the female adults was found at 32, 28 and 32 h after treated with BDMC, scopoletin, and their combination at the optimal mass ratio, respectively. The values of the LC₅₀ and LC₉₀ at 48 h after treated with BDMC, scopoletin, and their combination at the optimal mass ratio were 0.3324, 0.2035 and 0.2195 mg·mL^-1, and 2.1198, 0.9521 and 1.1617 mg·mL^-1，and the median lethal time (LT₅₀) of BDMC, scopoletin, and their combination at the optimal mass ratio was 7.4, 6.0 and 6.1 h at the concentration 1.0 mg·mL^-1, and 6.4, 4.8 and 5.0 h at the concentration 2.0 mg·mL^-1, respectively. The acaricidal activity and time-dose response of the optimal combination of scopoletin and BDMC were closer to those of scopoletin, suggesting a synergistic acaricidal activity of the combination of scopoletin and BDMC, which was worthy to be developed for application.

Melissopalynology and trophic niche of Apis cerana ceraca and Apis mellifera ligustica in Yunnan Province of Southwest China

LIU Yu-jia, ZHAO Tian-rui, ZHAO Feng-yun

2013, 24(1):  205-210. 

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In 2010 and 2011, the honey samples of Apis cerana cerana and A. mellifera ligustica were collected from Kunming and Mengzi of Yunnan Province, respectively, aimed to analyze the melissopalynology and tropic niche of the two bee species. The absolute pollen concentration of the honey of A. cerana cerana was 1.55×104 ind·g^-1, being significantly higher than that (1.01×104 ind·g^-1) of A. mellifera ligustica, and the number of nectar plant species collected by A. cerana cerana was 12.9, also significantly higher than that (7.7) collected by A. mellifera ligustica, indicating that A. cerana cerana could utilize more nectar plants, while A. mellifera ligustica had stronger selectivity to the nectar plants. The trophic niche breadth of A. cerana cerana was 0.35, which was significantly higher than that (0.23) of A. mellifera ligustica. The trophic niche overlap index between the two bee species was 0.71, and the interspecific competition index was 0.93, suggesting that the food competition between A. cerana cerana and A. mellifera ligustica was fierce.

Effects of cutting and reseeding on the ground-dwelling arthropod community in Caragana intermedia forest in desert steppe.

LIU Ren-tao, CHAI Yong-qing, YANG Xin-guo, SONG Nai-ping, WANG Xin-yun, WANG Lei

2013, 24(1):  211-217. 

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Taking a 25-year-old Caragana intermedia forest in desert steppe as test object, an investigation was conducted on the ground-dwelling arthropod community in cutting and no-cutting stands with and without reseeding, aimed to understand the effects of cutting, reseeding and their interaction on the individual number and group richness of grounddwelling arthropod in C. intermedia forest. There were significantly lower number and richness of ground-dwelling arthropod in the open spaces than under the shrubs in the no-cutting and no-reseeding stands. Cutting, reseeding and both of them could significantly increase the number and richness of ground-dwelling arthropod in the open spaces, but not under the shrubs,  compared with no cutting or reseeding. Consequently, there were no significant differences in the distribution of ground-dwelling arthropod in the open spaces and under the shrubs in the cutting, reseeding, or cutting and reseeding stands. Further, there was a similar buffer effect between cutting and reseeding on the ground-dwelling arthropod. No significant differences were observed in the ground-dwelling arthropod distribution, between cutting stand and reseeding stand, between cutting stand and cutting and reseeding stand, and between reseeding stand and cutting and reseeding stand. It was suggested that cutting, reseeding, or both of them could significantly improve the grounddwelling arthropod diversity especially in the open spaces, being beneficial for the restoration of degraded grassland ecosystem and the rational management on artificial C. intermedia forest in desert steppe.

Macrobenthos community structure and its relationships with environmental factors in Weihe River basin, Northwest China.

YIN Xu-wang1,2, XU Zong-xue1, GAO Xin3, BAI Hai-feng2, WU Wei1, SONG Jin-xi4

2013, 24(1):  218-226. 

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In October 2011, an investigation was conducted on the macrobenthos at 45 sampling sites in the Weihe River basin of Northwest China. A total of 116 macrobenthos species were collected, of which, 91 species (78.4%) were aquatic insects, 12 species (10.3%) were mollusks, 9 species (7.8%) were annelids, and 4 species (3.4%) were crustaceans. According to the species composition and relative abundance of macrobenthos, the 45 sampling sites could be divided into three groups by using twoway indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA). In the first group, Serratella sp., Hydropsyche sp., and Antocha sp. were the indicator species. In the second group, Tabanus sp., Alotanypus venustus, one species of Pelecorhynchidae, Liodessus sp., and Limnodrilus hoffmeistteri were the indicator species. In the third group, Ephemera nigroptera and Polypylis hemisphaerula were the indicator species. The canonical correspondence analysis (CCA) indicated that ‘cobble + boulder’ type substrate, current velocity, water conductivity, water depth, and water total nitrogen content had significant effects on the spatial distribution of macrobenthos in Weihe River basin.

Habitat suitability index model and minimum habitat area estimation of young Procypris rabaudi (Tchang): A simulation experiment in laboratory.

FENG Xian-bin1,2, ZHU Yong-jiu1,3, LI Xi1,2, HE Yong-feng1, ZHAO Jian-hua1,2, YANG De-guo1,2,3

2013, 24(1):  227-234. 

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Under the conditions of simulated micro-habitat in laboratory, and by using experimental ecological methods, this paper evaluated the suitability index (HSI) of young Procypris rabaudi for habitat factors (substrate, light intensity and water depth). The habitat suitability models of the young P. rabaudi were established, and the minimum habitat area of the young P. rabaudi was estimated. The young P. rabaudi preferred the habitats with the gravel diameter from 10 to 15 cm, light intensity from 0.2 to 1.8 lx, and water depth from 0 to 15 cm (distance from the bottom of the tank). The three suitability index models of the substrate, light intensity and water depth for the young P. rabaudi were SI_S=1.7338e^-0.997x(SI_S is the suitability index of substrate, and x is the gravel diameter; R²=0.89, P<0.01), SI_L=3.0121e^-1.339x(SI_L is the suitability index of light intensity, and x is the light intensity; R²=0.93,P<0.01), and SI_W=2.4055e^-1.245x(SI_W is the suitability index of water depth, and x is the water depth; R²=0.97, P<0.01), respectively. Arithmetic mean model HSI=(SI_S+SI_L+SI_W)/3 was most available for the estimation of the habitat suitability of young P. rabaudi. A total of seven groups of young P. rabaudi which established and maintained a relatively stable habitat area range were found. This habitat area ranged from 628 to 2015 cm², with an average of 1114 cm².

Hydroacoustic assessment of fish resources in reservoirs with different fishery management.

SUN Ming-bo1,2, GU Xiao-hong1, ZENG Qing-fei1, MAO Zhi-gang1,2, GU Xian-kun1,2

2013, 24(1):  235-242. 

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By using Biosonics DT-X echosounder (208 kHz), a hydroacoustic investigation was conducted on the fish resources in three mesotrophic reservoirs (Daxi Reservoir, Shahe Reservoir, and Jinniushan Reservoir) with different fishery management in late autumn and early winter 2011, and a GIS model was constructed to assess the fish resource distribution in the reservoirs. No significant difference was observed in the average size of fish in the three reservoirs, but the distribution curves of fish target strength (TS) showed that the fish size distribution proportion was different, and had close correlation with fishery management. The fish density in Daxi Reservoir (averagely 0.0183 ind·m^-3) had no significant difference with that in Shahe Reservoir (averagely 0.0124 ind·m^-3),but the fish density in Jinniushan Reservoir (averagely 0.0085 ind·m^-3) was significantly lower than that in Daxi and Shahe reservoirs. There was no significant correlation  between the horizontal distribution of fish density and the water depth in the three reservoirs. The fish in the three reservoirs were in group distribution, and fish aggregation was found in Daxi and Shahe reservoirs. In the three reservoirs, the fish biomass was the highest in downstream, and there was a greater biomass near the dam, except in Shahe Reservoir which was affected by fish catch activity. Based on the raster data obtained from GIS fish distribution model and the surface water area of each grid, the total amount of fish resources with the TS >-60 dB in the Daxi, Shahe and Jinniushan reservoirs was estimated as about 480000, 610000 and 520000 individuals, and that with the TS >-40 dB was about 50400, 52900 and 90700 individuals, respectively.

Phytoplankton’s community structure and its relationships with environmental factors in the rivers of Tongling City, Anhui Province of East China in winter.

WANG Li, WEI Wei, ZHOU Ping, LI Yang, SUN Qing-ye

2013, 24(1):  243-250. 

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Tongling is one of the main nonferrous metal mining areas in China, and the biodiversity in the river ecosystem of this area is seriously affected by heavy metals as a result of mining activities. In the winter in 2010, an investigation was conducted on the community structure of phytoplankton and its relationships with environmental factors in the main sections of the rivers in Tongling. A total of 203 phytoplankton species were identified, belonging to 96 genera and 8 phyla. The community structure of the phytoplankton differed obviously in different river sections, but the communities were all dominated by Bacillariophyta, Chlorophyta and Cyanophyta. The phytoplankton abundance ranged from 9.1×10³  to 6.5×10⁷ cells·L^-1, and the quantity of the phytoplankton in the river sections directly carried with mining waste water was significantly low. The Shannon index of the phytoplankton community at different sampling sites ranged from 0 to 3.45, with a significant discrepancy in different river sections. There existed significant correlations between the density and group number of phytoplankton and the COD_Cr and cadmium, copper and zinc concentrations in the rivers, and the concentrations of river total nitrogen, NH₄⁺-N, NO₃^--N, and copper, COD_Cr and pH were the main environmental variables affecting the phytoplankton’s community structure and its spatial distribution. Although the nutritional status of the river waters had greater effects on the community structure of phytoplankton, the effects of the heavy metals there from mining enterprises could not be neglected.

Effects of vegetation on river flow: A review.

XU Wei-gang, ZHANG Hua-yong, WANG Zhong-yu, HUANG Wen-pei

2013, 24(1):  251-259. 

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Vegetation is a component of the natural river. To understand the interaction between vegetation and water flow is of scientific and practical significance for the protection of wildlife habitats, the control of water body eutrophication, the ecological restoration of rivers and lakes, and the management of riverways. This paper reviewed the researches about the interaction between vegetation and water flow in riverways, summarized the research progress in the effects of the vegetation on the resistance coefficient and water flow structure, and introduced the applications of numerical simulation in this research field. Based on the previous studies, the effects of river section shape, plant individual form, and vegetation distribution pattern on the flow regime of water flow in vegetation section were analyzed. For further study, the importance of deeply understanding the hydraulics mechanisms of the interaction between vegetation and water flow in terms of the diversity of river morphology, the vegetation variation at different spatiotemporal scales, the water flow distribution in vegetation section, and the three dimensional turbulent simulation was expatiated.

Phosphorus availability in cropland soils of China and related affecting factors.

WANG Yong-zhuang1,2, CHEN Xin1, SHI Yi1

2013, 24(1):  260-268. 

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Soil phosphorus (P) availability directly determines cropland productivity. Based on the long-term fertilization experiments in different climatic zones of China, this paper summarized the P content, its availability, and the factors affecting the P transformation in China cropland soils. The total and available P contents in different types of China cropland soils were 0.31-1.72 g·kg^-1 and 0.1-228.8 mg·kg^-1, respectively. Soil parent material, soil physical and chemical prosperities, and fertilization practices were the main factors affecting the soil P availability. It was suggested that more attentions should be paid on the mixed application of organic manure and chemical fertilizers to improve the P availability of  cropland soils and on the potential environmental impacts of this fertilization.

Research progress on photosynthesis regulating and controlling soil respiration.

JING Yan-li1,2, GUAN De-xin1, WU Jia-bing1, WANG An-zhi1, YUAN Feng-hui1

2013, 24(1):  269-276. 

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To understand the mechanisms of soil respiration and accurately estimate its magnitude are the crucial basis of evaluating global carbon balance. However, the previously built soil respiration forecast models usually neglect the physiological processes that photosynthesis supplies substrates for rhizospheric respiration, leading to the defect in evaluating the mechanisms of soil respiration. This paper summarized the research progress on the mechanisms of photosynthetic regulation and control of soil respiration, introduced the related main research methods, and discussed the existing problems and research hotspots.

Nitrogen balance in dairy farm: Research progress. 

LU Chao, QIN Wen-xiao, GAO Teng-yun, WANG Xiao-xiao, HAN Zhi-guo, LI Jia

2013, 24(1):  277-285. 

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Large dairy farm with intensive management has high stocking density, but generally does not have enough space and normative feces disposal system, resulting in the discharged nitrogen surpassed the environmental carrying capacity of unit area land. Dairy farm is one of the major emission sources of nitrogen discharges in agriculture, where the nitrogen balance has being aroused attention by the experts abroad. The research on the nitrogen flow and nitrogen balance in dairy farm is the basis of the dairy farm nitrogen cycling and management study, as well as the basis for the construction of environmental laws, regulations and policies. The most reliable indicators to evaluate the nitrogen flow and nitrogen balance in dairy farm are nitrogen surplus and nitrogen use efficiency. This paper introduced the concept of nitrogen balance on farmscale and the nitrogen flow within farm, compared the application scope of nitrogen surplus and nitrogen use efficiency, analyzed the factors affecting the nitrogen balance in dairy farm, and summarized the effective strategies to reduce the nitrogen discharges from dairy farm, aimed to provide references for the nitrogen management of dairy farm in China.

Weight of evidence (WOE) approach and its application in sediment quality assessment of coastal ecosystem: A review.

WU Bin1,2, SONG Jin-ming1, LI Xue-gang1, YUAN Hua-mao1, LI Ning1

2013, 24(1):  286-294. 

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At present, chemical approaches are the main tools adopted to assess the contaminated sediments along China’s coast. However, with the crucial progress of weight of evidence (WOE) approach in both logic and practice, this approach is getting available to be applied in the sediment quality assessment of our coastal ecosystem. By incorporating the levels of evidences such as sediment chemistry, toxicity and benthic community ecology, WOE forms an integrated approach to assess the potential adverse biological effects of environmental stressors mainly toxic substances by reconciling the information from multiple relevant lines of evidences and by weighing the data quality, study design, and other factors, being the sole means currently available to characterize the actual sediment quality and to reach an environmental decision. This paper reviewed the history of sediment quality assessment and the progress of WOE research in coastal sediment, summarized the variety of WOE definitions and interpretive techniques with reliability analysis, and discussed the limitations of WOE in theory and practice. Several improvement suggestions were proposed associated with the prospects of WOE research to advance the coastal sediment quality assessment in China.

Research progress on using index of biological integrity to assess aquatic ecosystem health.

LIAO Jing-qiu, HUANG Yi

2013, 24(1):  295-302. 

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Index of biological integrity (IBI) is one of the most important and popular tools in assessing aquatic ecosystem health. This paper reviewed the selection of indicator species for IBI, its construction process, and its applications in assessing aquatic ecosystem health, summarized the commonly used candidate biological parameter indices of fishindex of biological integrity (F_IBI), benthosindex of biological integrity (B_IBI), and periphytonindex of biological integrity (P_IBI), and pointed out the feasibility and necessity of using microbe-index of biological integrity (M_IBI) to assess the health of aquatic ecosystem.