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Table of Content

    18 December 2010, Volume 21 Issue 12
    Articles
    Soluble organic carbon in plant litters on Loess Plateau: Content and biodegradability.
    2010, 21(12):  3001-3006. 
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    The litters of eight plant species from the Loess Plateau were cut into pieces with 2 mm and 1 cm in size, and extracted with distilled water and 0.01 mol·L-1 CaCl2 to determine the soluble organic carbon (SOC) content. In the meantime, a 7-day indoor incubation test was conducted at (25±3) ℃ to investigate their biodegradability. The SOC content and the ratio of SOC to total carbon (SOC/TC) in the litters were 18.20-156.82 g·kg-1 and 4.21%-32.84%, respectively. Shrub litter had a slightly higher SOC content than tree litter, while grass litter had the lowest SOC content. After 7-day incubation, the biodegradation rate of SOC in the plant litters ranged from 44.5% to 80.6% (62.9% on average), and decreased in the order of shrub > tree > grass. By the end of the incubation, the proportion of soluble organic matter in solution had a significant increasing trend, which was related to the rapid biodegradation of labile composition in the litters. The higher content and higher biodegradation rate of SOC in plant litters might play important roles in nutrient cycling and energy flow during the vegetation restoration on Loess Plateau.
    Net photosynthesis and its affecting factors in a tropical seasonal rainforest ecosystem in Southwest China.
    2010, 21(12):  3007-3014. 
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    By using eddy covariance technique, this paper quantitatively analyzed the photosynthetic characteristics of tropical seasonal rainforest ecosystem and related environmental controlling factors in Xishuangbanna in 2003-2006. In the study period, less interannual difference was observed in the net photosynthesis of the ecosystem, with the maximum photosynthesis rate (Peco,opt), respiration at daytime (Reco,d), and apparent quantum yield (α) averaged by 0.813 mg·m-2·s-1, 0.238 mg·m-2·s-1, and 0.0023 mg·μmol-1, respectively. As affected by the interaction of air temperature (Ta) and vapor pressure deficit (VPD), the photosynthetic characteristics had some seasonal differences. In rainy season, the ecosystem had the strongest photosynthetic capacity because of the higher precipitation and warmer air temperature; in foggy and cool season, fog drip played an important role in the water relations of plants, and thereby, the ecosystem photosynthetic capacity was still higher; in dry and hot season, due to the limited precipitation and high temperature, the Ta and VPDincreased, inducing a decrease of ecosystem α and Peco,opt. The net CO2 exchange of the ecosystem strongly depended on the Ta above 20 ℃ and the VPD above 1 kPa.
    Effects of snow cover on soil temperature in broad-leaved Korean pine forest in Changbai Mountains.
    2010, 21(12):  3015-3020. 
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    A snow-shading experiment was conducted in a broad-leaved Korean pine forest in Changbai Mountains from 2004 to 2007 to observe the soil temperature with and without snow cover. Snow cover played an important buffering role in the change of soil temperature, namely, slowed down the change process of soil temperature. The effect of snow cover on preserving soil heat was quite obvious in shallow soil layer (0-20 cm), and enhanced with increasing snow depth. When the snow depth increased from 10 to 20 cm, the effect enhanced significantly. However, when the snow depth exceeded 30 cm, the increasing trend turned to indistinctive. In the period of snow-melting, soil temperature kept around 0 ℃ for some time, and after then, increased gradually. The length of the period keeping soil temperature around 0 ℃ was determined by snow depth and the duration of snow cover.
    Canopy interception in larch plantations: Measurement and modeling in Eastern Liaoning Mountainous Region.
    2010, 21(12):  3021-3028. 
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    Based on the 2005-2008 observation data of canopy interception in larch  plantation in eastern Liaoning Province, and by using Gash model, the interception process was simulated. In the plantation, there was a significant positive correlation between throughfall and rainfall (R2=0.98), and the annual throughfall accounted for 77.64% of the total rainfall. The canopy interception was positively correlated with rainfall and its intensity. The canopy interception simulated by Gash model was lower than the measured values, except for the results in 2007 because of the short intervals between rainfalls. The absolute error of simulated values had a negative exponential correlation with rainfall, and the range was 1.26%-68.96%, and the mean value was 29.09%. The estimated values were almost equal to the measured values, with the correlation coefficient being 0.91.
    Soil water resource use limit in semi-arid loess hilly area.
    2010, 21(12):  3029-3035. 
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    Taking Caragana korshinskii as test object, and by using neutron probe, a long term observation was conducted on the soil water and plant growth during the process of vegetation restoration in semi-arid loess hilly area. The results showed that after seeding on waste land, the capability of plant community in conserving soil and water was promoted with time, with the depth of roots to absorb and use soil water increased and the soil water content reduced. Then, the dried soil layer appeared, and its deepness and thickness increased with increasing plant age. Therefore, the plant use of soil water had a limit, soil water resource use limit, i.e., the soil water storage when the deepness of dried soil layer was equal to the largest depth that rain could recharge. In the C. korshinskii woodland in semi-arid loess hilly area, the soil water resource use limit in 0-290 cm layer was 249.4 mm. When the soil water storage in  woodland was close or equal to the soil water resource use limit, effective measures should be taken to decrease soil evapotranspiration or increase soil water supply to ensure the sustainable water use of plant roots.
    Selection of biomass estimation models for Chinese fir plantation.
    2010, 21(12):  3036-3046. 
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    A total of 11 kinds of biomass models were adopted to estimate the biomass of single tree and its organs in young (7-year old), middle-age (16-year old), mature (28-year old), and mixed-models fitted. Among the 11 kinds of biomass models, power function models fitted best, followed by exponential models, and then polynomial models. Twenty-one optimal biomass models for individual organ and single tree were chosen, including 18 models for individual organ and 3 models for single tree. There were 7 optimal biomass models for the single tree in the mixed-age plantation, containing 6 for individual organ and 1 for single tree, and all in the form of power function. The optimal biomass models for the single tree in different age plantations had poor generality, but the ones for that in mixed-age plantation had a certain generality with high accuracy, which could be used for estimating the biomass of single tree in different age plantations. The optimal biomass models for single Chinese fir tree in Shaowu of Fujian Province were used to predict the single tree biomass in mature (28-year old) Chinese firplantation in Jiangxi Province, and it was found that the models based on a large sample of forest biomass had a relatively high accuracy, being able to be applied in large area, whereas the regional models with small sample were limited to small area.
    Effects of drying and re-watering on the photosynthesis and active oxygen metabolism of Periploca sepium seedlings.
    2010, 21(12):  3047-3055. 
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    Taking two-year old Periploca sepium seedlings as test materials, an experiment with controlled soil water contents was conducted to study the effects of repeated drying and re-watering on the leaf photosynthetic characteristics and the lipid peroxidation and antioxidant system in young leaves, mature leaves, old leaves, new stems, and fine roots. The seedlings were subjected to three cycles of drying and re-watering, with regular irrigation to maintain the soil water content at around 80% of field capacity as the control (CK). Under drying, the leaf relative water content (RWC) and net photosynthesis rate (Pn) decreased significantly, while the leaf photosynthetic pigments content increased. When the seedlings were re-watered, their leaf RWC recovered to the CK level, showing a strong repair capacity after drying. Both the leaf chlorophyll content and the Pn after repeated drying and re-watering presented a higher level than those of the CK, indicating a compensatory effect appeared and an appropriate drought stress being able to induce the adaptability of P. sepium to drought stress. Stomatal closure was the main factor limiting P. sepium photosynthesis under drought stress, while non-stomatal limitation only worked at noon. Under drying, the superoxide anion radical (O2) production rate in young leaves, new stems, and fine roots increased while the malondialdehyde (MDA) contents decreased, suggesting that these young tissues were not suffered from the oxidative stress. The activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in different organs had different variation trends, with those in fine roots changed actively, suggesting the important role of fine roots in the acclimation of P. sepium to drought environment. It was the cooperation and coordination among plant organs that made P. sepium more adaptive to the repeated drying and wetting conditions in drought -prone regions.
    Effects of nitrogen and carbon addition and arbuscular mycorrhiza on alien invasive plant Ambrosia artemisiifolia.
    2010, 21(12):  3056-3062. 
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    A greenhouse control experiment was conducted to explore the effects of nitrogen and carbon addition and arbuscular mycorrhiza (AM) on the growth of alien invasive plant Ambrosia artemisiifolia (common ragweed). Nitrogen addition had no significant effects on the morphological indices, biomass and its allocation, and absolute growth rate of A. artemisiifolia, but increased the nitrogen content in the aboveground and underground parts of the plant significantly. Carbon addition increased the content of soil available nitrogen. In this case, the biomass allocation in root system for nutrient (nitrogen) absorption promoted, resulting in a remarkable decrease of branch number, total leaf area, specific leaf area (SLA), and leaf mass ratio. As a result, the total biomass decreased significantly. The symbiosis of A. artemisiifolia and AM fungi had great influence on the common ragweed’s soil nitrogen acclimation, which enhanced its resource-capture by the increase of SLA, and this effect was more significant when the soil nitrogen content was low. AM fungi played an important role in the growth of A. artemisiifolia in low-nitrogen environment.
    Prediction of potential suitable distribution area of Flaveria bidentis in China based on niche models.
    2010, 21(12):  3063-3069. 
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    Based on the distribution records of Flaveria bidentis in China, and by using five ecological niche models (GARP, Maxent, ENFA, Bioclim, and Domain), 32 eco-geographical variables were chosen to simulate the potential suitable distribution area of F. bidentis in the country, and the simulation precision of the models was assessed by the method of Receiver Operating Characteristic (ROC) curve analysis. Among the models adopted, Maxent model had the best simulation precision. Its prediction showed that the potential suitable distribution area of F. bidenti in this country accounted for 7.5% of the total, with the central and southern Hebei, Beijing, Tianjin, Henan, Shandong, Anhui, and Jiangsu having high potential invasion risk.
    Effects of compaction on diurnal variation of soil respiration in Larix gmellinii plantation in summer.
    2010, 21(12):  3070-3076. 
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    Taking the Larix gmellinii plantation in the experimental forest farm of Northeast Forestry University as test object, and by using Li-8100 automatic instrument, the daily CO2 emission rate of soil in summer under different degrees of man-made compaction was measured, with the regression models established. There were significant differences in the diurnal variation of soil respiration rate under different degrees of man-made compaction. In CK (no compaction), the maximum value of soil respiration appeared at 15:30-17:30, and the minimum value appeared at 03:30-05:30, which were obviously lagged behind those in compaction treatments. The maximum and minimum values of soil respiration rate in main roads appeared at 09:30-11:30 and 23:30-01:30, and those in branch roads appeared at 11:30 and 01:30-03:30, respectively. In all treatments, soil respiration rate had significant correlations with surface temperature, relative humidity, and the temperature at 10 cm soil depth, but the correlation with the soil moisture at 5 cm depth tended to be not significant when the compaction degree was increasing. Compaction altered surface soil physical structure, decreased surface soil CO2 release rate.
    Relationships between leaf surface characteristics and dust-capturing capability of urban greening plant species.
    2010, 21(12):  3077-3082. 
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    Taking 21 representative urban greening species in Xi’an as test objects, their leaf dust-capturing capability was determined by artificial dust-deposition method, and the relationships between the dust-capturing capability and leaf surface features, e.g., trichomes, wettability, surface free energy and its polar and dispersive components on dust-capturing capability were studied. For the tested 21 species, their maximum leaf dustcapturing capability was 0.8-38.6 g·m-2, and there was a significant difference among them, with the greatest variation up to forty times. The amount, distribution, and morphology of trichomes had great influence on the leaf dust-capturing capability, possibly due to the different action patterns between trichomes and particulate matters. There was a significant negative relationship between leaf contact angle and maximum leaf dust-capturing capability (r=-0.523), except for four species whose leaf surface has trichomes. For wettable leaves, their maximum dust-capturing capacity ranged from 2.0 to 8.0 g·m-2, but for nonwettable leaves, their maximum dust-capturing capacity was below 2.0 g·m-2. The leaf surface free energy was mainly manifested in the action of dispersive component, while the contribution of polar free energy was lower than 20%, which could be related to the existence of non-polar or weakly polar substances on leaf surface. The leaf surface free energy and its dispersive component had a significant positive correlation (r=0.500, 0.572) with the maximum leaf dust-capturing capability, but the positive correlation between polar free energy and maximum dust-capturing capability was not significant (r=0.244).
    Spatial optimum allocation of shelter-forest types in Three Gorges Reservoir Area based on multiple objective grey situation decision.
    2010, 21(12):  3083-3090. 
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    Based on the 2007 Landsat TM images and the dominant environmental factors of shelter forest, the forest sites in the Three Gorges Reservoir Area were classified, and by using multiple objective grey situation decision model, three indices including water conservation amount, biomass, and stand productivity were selected to make the spatial optimum allocation of the present four kinds of shelter forest (coniferous forest, broadleaf forest, mixed coniferousbroadleaf forest, and shrub) in the Area. The forest sites in the Area in 2007 could be classified into 40 types, and after the optimization of spatial allocation, the proportion of coniferous forest, broadleaf forest, mixed coniferous-broadleaf forest, and shrub would be 32.55%, 29.43%, 34.95%, and 3.07%, respectively. Comparing with that before optimization, the proportion of coniferous forest and shrub after optimization was reduced by 8.79% and 28.55%, while that of broadleaf forest and mixed coniferous-broadleaf forest was increased by 10.23% and 27.11%, respectively. After the optimization of spatial allocation, the amount of water conservation, biomass, and stand productivity of the shelter forests in the area would be increased by 14.09×108 m3, 0.35×108 t, and 1.08×106 t, respectively.
    Spatial pattern of vegetation landscape diversity in Longitudinal Range-Gorge Region, Southwestern China.
    2010, 21(12):  3091-3098. 
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    Based on the China 1:1000000 vegetation type map, and by using GIS spatial analysis, the spatial pattern of major vegetation landscape diversity indices and its relationships with environmental factors in Longitudinal Range-Gorge Region (LRGR) were analyzed. The proper scale for studying the vegetation landscape diversity in LRGR was 2000 m. In the study region, an obvious regional difference was observed in the vegetation landscape diversity indices, exhibiting typical longitudinal “corridor” and latitudinal “barrier” characteristics. The correlations between the vegetation landscape diversity indices and environmental elements were significant, and the regional difference in the environmental elements was the main factor controlling the spatial pattern of vegetation landscape diversity indices. The “corridor-barrier” function of the longitudinal range-gorge terrain made a spatial redistribution of hydro-thermal conditions, being the main cause of the special pattern of the vegetation landscape diversity
     in LRGR.
    Spatial pattern of soil fertility |in Bashan tea garden: A prediction based on environmental auxiliary variables.
    2010, 21(12):  3099-3104. 
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    Taking topographic factors and NDVI as auxiliary variables, and by using regression-kriging method, the spatial variation pattern of soil fertility  in Bashan tea garden in the hilly area of Fuyang City was explored. The spatial variability of the soil fertility  was mainly attributed to the structural factors such as relative elevation and flat/vertical curvature. The lower the relative elevation, the worse the soil fertility  was. The overall soil fertility level was relatively high, and the area with lower soil fertility only accounted for 5% of the total. By using regression-kriging method with relative elevation as auxiliary variable, the prediction accuracy of soil fertility  was obviously higher than that by using ordinary kriging method, with the mean error and root mean square error being 0.028 and 0.108, respectively. It was suggested that the prediction method used in this paper could fully reflect the effects of environmental variables on soil fertility , improve the prediction accuracy about the spatial pattern of soil fertility, and provide scientific basis for the precise management of tea garden.
    Dynamic changes of urban architecture landscape based on Barista: A case study in Tiexi District of Shenyang City.
    2010, 21(12):  3105-3112. 
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    In this paper, three-dimensional building information was extracted from high resolution satellite image based on Barista software. Combined with ArcGIS software, the dynamic changes of the building landscape in Tiexi District of Shenyang City during urban renewal process were analyzed from the conversion contribution rate, building density, average building height, and built-up area rate. It was found that during this urban renewal process, four dominant landscape types (vacant lot, residential building, industrial building, and road) were the main parts of the landscape changes. The areas of vacant lot, residential building, commercial building, and road increased, while that of industrial building decreased. The building density decreased, while the average building height increased. There was an obvious regional variation in building landscape. The building density in industrial district was higher than that in residential district, while the average building height was in adverse. The further from the city center, the lower the building density and building average height.
    Impacts of cultivated land conversion on cultivated land productivity in China: Prediction and analysis.
    2010, 21(12):  3113-3119. 
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    This paper simulated the spatial patterns of cultivated land in China under the future scenario by using the Dynamics of Land System (DLS) model, and then estimated the cultivated land productivity at the grid pixel dimensions based on the Estimation System of Land Production (ESLP). In addition, the spatial patterns of cultivated land productivity in each of China agro-ecological zones were analyzed. On this basis, this paper predicted the impacts of cultivated land conversion on the cultivated land production in China in 2000-2020, and identified the major affecting factors on the cultivated land production. The research results indicated that the impact of improving the cultivated land productivity on the cultivated land production would be wunch more remarkable than that from the magnitude of cultivated land conversion in regions where there were high potential to imrprove the cultivated land productivity. However, in the regions with nearly no room to improve the productivity, cultivated land conversion would produce more apparent impacts on the total cultivated land production. In this sense, it was of significance for the national food security in China to adjust the cultivated land conversion to ensure the 0.12 billion hm2 of cultivated land, and to increase investment and improve management level to increase per unit grain yield.
    Dynamics of recent cultivated land in Zhejiang Province and relevant driving factors.
    2010, 21(12):  3120-3126. 
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    Through the human-computer interactive interpretation of the 2000, 2005, and 2008 remote sensing images of Zhejiang Province with the help of RS and GIS techniques, the dynamic database of cultivated land change in the province in 2000-2008 was established, and the driving factors of the cultivated land change were analyzed by ridge regression analysis. There was a notable cultivated land change in the province in 2000-2008. In 2000-2005 and 2005-2008, the annual cultivated land change in the province arrived -1.42% and -1.46%, respectively, and most of the cultivated land was changed into residential and industrial land. Non-agricultural population rate, real estate investment, urban green area, and orchard area were thought to be the main driving factors of the cultivated land change in Zhejiang Province, and even, in the developed areas of east China.
    Surrounding characteristics of preferential flow in cultivated typical black soils of Northeast China.
    2010, 21(12):  3127-3132. 
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    Taking the cultivated soils in typical black soil region of Northeast China as test objects, and by using dye tracer and double-ring infiltrometer techniques and photograph interpretation method, this paper measured and analyzed the dye-stained width and dye-stained coverage of soil transverse and longitudinal sections as well as the field maximum dye-stained depth, aimed to approach the water flow movement pattern and distribution characteristics in test soils. At soil depth 0-15 cm, matrix flow was the main soil water flow movement pattern; at depth 15-20 cm, lateral flow was observed, and the average dye-stained width and dye-stained coverage reached their maximum, being 23 cm and 20.73 %, respectively. At depth 20-67 cm, the main soil water flow movement pattern was macro-pore flow, with cracks and macro-pores as the main preferential routes. The cracks at depth 20-35 cm made the preferential flow have distinct surrounding characteristics, and the macro-pores at depth 40-67 cm were the main preferential routes. Due to the existence of the preferential routes of cracks and macro-pores, the migration velocity of water in soil increased by 4.5 times, which could not only cause water loss, but also accelerate the migration of pesticides to ground water. It was suggested that these preferential routes should be decreased or eliminated during the cultivation and management on cultivated typical black soils.
    Effects of carbon source and flooding time on microbial Fe(Ⅲ) reduction in paddy soils.
    2010, 21(12):  3133-3140. 
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    Paddy soil samples were collected from six provinces of China, and an anaerobic incubation test was conducted to examine the microbial Fe(Ⅲ) reduction potential under the conditions of different flooding time and with glucose, pyruvate, lactate, or acetate as the sole carbon source. The results showed that flooding time had significant effects on the eigenvalue of Fe(Ⅲ) reduction, Vmax, with the order of 20 d > 30 d > 12 d > 1 d > 5 d, which suggested that the difference in the microbial community structure in different flooding periods was the main reason inducing the different potential of Fe(Ⅲ) reduction. In all test flooding periods, glucose and pyruvate were the superior carbon sources, with the Fe(Ⅲ) reduction rate being 88.1%-99.9% and 58.0%-97.9%, respectively. When lactate was amended, the Fe(Ⅲ) reduction rate varied greatly among different paddy soils. For the paddy soils from Hunan and Zhejiang, the Fe(Ⅲ) reduction rate during flooding period could reach 87.1%-100%; while for other soils, it was 5.0%-49.4% in the first 5 days of flooding and 52.2%-99.9% in 12 days after flooding. When acetate was used as a carbon source, the Fe(Ⅲ) reduction rate increased with flooding time. Especially in the paddy soil from Zhejiang, the Fe(Ⅲ) reduction rate changed greatly from 5.3% to 75.8%.
    Effects of low light on photosynthetic characteristics of tomato at different growth stages.
    2010, 21(12):  3141-3146. 
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    Taking low light tolerance tomato strains 02S02 and 02S32 and sensitive strains 02S52 and 02S57 as test objects, this paper studied their leaf photosynthetic characteristics at seedling stage, flowering-fruit-setting stage, and fruit-inflating stage under effects of low light. The experiment was carried out in a low light environment, a plastic tunnel covered with black shading nets, with the light intensity being about 50% of that in normal plastic tunnel (average light intensity 800 μmol·m-2·s-1at sunny morning 9:00-11:00). For the four test tomato strains, their leaf photosynthetic rate in low light environment had a slight increase, but decreased greatly when the light intensity increased, with the change trends being similar but the change degree differed with strains and growth stages. The light compensation point and dark respiration rate decreased gradually with plant growth, and the decrement was larger for low light tolerance strains than for sensitive strains. The light saturation point, maximum photosynthetic rate, and apparent quantum yield decreased at all the growth stages, but the decrements differed with growth stages and were not consistent with the low light tolerability of test strains.
    Effects of applying controlled-release fertilizer blended with conventional nitrogen fertilizer on Chinese cabbage yield and quality as well as nitrogen losses.
    2010, 21(12):  3147-3153. 
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    An open field experiment was conducted to study the effects of applying controlled-release fertilizer blended with rapidly available chemical N fertilizer on Chinese cabbage yield and quality as well as nitrogen losses, including ammonia volatilization and NO3--N accumulation and leaching in Beijing suburb. The results showed that a combined application of 2:1 controlled-release fertilizer and urea fertilizer (total N rate 150 kg·hm-2) did not induce the reduction of Chinese cabbage yield, and decreased the leaf nitrate and organic acid contents significantly, compared with conventional urea N application (300 kg·hm-2), and had no significant difference in the cabbage yield and leaf nitrate content, compared with applying 150 kg·hm-2 of urea N. The combined application of 2:1 controlledrelease fertilizer and urea fertilizer improved the N use efficiency of Chinese cabbage, and reduced the ammonia volatilization and NO3--N leaching. At harvest, the NO3--N concentrations in 20-40, 60-80 and 80-100 cm soil layers were significantly lower in the combined application treatment than in urea N treatment.
    Effects of water-fertilizer spatial coupling in root zone on winter wheat growth and yield.
    2010, 21(12):  3154-3160. 
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    A soil column experiment was conducted to study the winter wheat growth and yield under effects of different soil wetting (overall wetting, upper part wetting, and lower part wetting) and fertilization (overall fertilization, upper part fertilization, and lower part fertilization). The plant height and leaf area at tillering stage decreased significantly under lower part fertilization, compared with those under upper part and overall soil fertilization, but had no significant differences under different soil wetting. At jointing stage, the plant height was higher when the soil wetting and fertilization were at same location than at different location, manifesting a synergistic coupling effect of water and fertilizer. Lower part soil wetting and lower part fertilization decreased the root, shoot, and total dry biomass significantly, upper part fertilization benefited the biomass accumulation of winter wheat, and upper part soil wetting combined with upper part fertilization had an obvious coupling effect on the shoot-and total dry biomass. Soil wetting and fertilization at same location induced a higher ratio of root to shoot, compared with soil wetting and fertilization at different location, and lower part soil wetting resulted in the maximum water use efficiency (WUE), compared with upper part and overall soil wetting. A higher WUE was observed in the soil wetting and fertilization at same location than at different location, but a lower WUE was induced by lower part fertilization. The grain number per spike under upper part and overall soil wetting was increased by 41.7% and 61.9%, respectively, compared with that under lower part soil wetting, and this yield component under upper part and overall soil fertilization was also higher, compared with that under lower part fertilization. Upper part soil wetting and fertilization had an obvious coupling effect of water-fertilizer on the yield and yield components (except for 1000 grain mass). Different soil wetting and fertilization affected the yield mainly through affecting the grain number per spike.
    Spatiotemporal characteristics of reference crop evapotranspiration in inland river basins of Hexi region.
    2010, 21(12):  3161-3167. 
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    Based on the 1961-2008 daily observation data from 17 meteorological stations in the inland river basins in Hexi region, the daily reference crop evapotranspiration (ET0) in the basins was computed by Penman-Monteith equation, and the spatiotemporal characteristics of seasonal and annual ET0 were studied by GIS and IDW inverse-distance spatial interpolation. In 1961-2008, the mean annual ET0 (700-1330 mm) increased gradually from southeast to northwest across the basins. The high value of mean annual ET0 in Shule River basin and Heihe River basin declined significantly (P<0.05), with the climatic trend rate ranged from -53 to -10 mm·(10 a)-1, while the low value of mean annual ET0 in Shiyang River basin ascended slightly. The ET0 in the basins had a significant annual fluctuation, which centralized in Linze and decreased toward northwest and southeast. The ET0 in summer and autumn contributed most of a year, and the highest value of ET0 all the year round always appeared in Shule River basin. The climatic trend rate was in the order of summer > spring > autumn > winter. Wind speed and maximum temperature were the primary factors affecting the ET0 in the basins. Furthermore, wind speed was the predominant factor of downward trend of ET0 in Shule and Heihe basins, while maximum temperature and sunshine hours played an important role in the upward trend of ET0 in Shiyang basin.
    Ecological cost of grain production in gully area of Loess Plateau.
    2010, 21(12):  3168-3174. 
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    Economic and ecological methods were applied to investigate the ecological cost of grain production in the gully area of Loess Plateau. In the study area in 2008, the ecological loss due to grain production was 7.2% of the total crop output, and the ecological cost reached 2.42 yuan·kg-1 for wheat and 2.12 yuan·kg-1for corn. However, the per unit sales were 1.70 yuan·kg-1 for wheat and 1.28 yuan·kg-1 for corn. The combination of high production cost and low income affected the sustainable development of local ecological economy. The analysis of grey relationships among various factors affecting the ecological cost of grain production indicated that yield, sown area, and agricultural mechanical cost were the important factors affecting the ecological cost of grain production, while chemical fertilizer cost and organic fertilizer cost had less impact on the ecological cost of grain production. Under current production conditions, the ecological cost of grain production in the area could be reduced by raising the level of scientific and technological inputs, expanding the scale of family agricultural production, and improving the grain yield.
    Estimation of optimum normalized difference spectral index for nitrogen accumulation in wheat leaf based on reduced precise sampling method.
    2010, 21(12):  3175-3182. 
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    Four independent field experiments with 6 wheat varieties and 5 nitrogen application levels were conducted, and time-course measurements were taken on the canopy hyperspectral reflectance and leaf N accumulation per unit soil area (LNA, g N·m-2). By adopting reduced precise sampling method, all possible normalized difference spectral indices [NDSI(i, j)] within the spectral range of 350-2500 nm were constructed, and the relationships of LNA to the NDSI(i, j)were quantified, aimed to explore the new sensitive spectral bands and key index from precise analysis of groundbased hyperspectral information, and to develop prediction models for wheat LNA. The results showed that the sensitive spectral bands for LNA were located in visible light and near infrared regions, especially at 860 nm and 720 nm for wheat LNA. The monitoring model based on the NDSI(860,720) was formulated as LNA=26.34×[NDSI(860,720)]1.887, with R2=0.900 and SE=1.327. The fitness test of the derived equations with independent datasets showed that for wheat LNA, the model gave the estimation accuracy of 0.823 and the RMSE of 0.991 g N·m-2, indicating a good fitness between the measured and estimated LNA. The present normalized hyperspectral parameter of NDSI(860,720) and its derived regression model could be reliably used for the estimation of winter wheat LNA.
    Effects of arsenic on maize growth, antioxidant system, and ion distribution.
    2010, 21(12):  3183-3190. 
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    A greenhouse sand culture experiment was conducted to study the effects of arsenic (As) on the biomass accumulation, photosynthetic pigments, antioxidant system, and the absorption and distribution of As and mineral ions in maize Zhengdan 9.58. At lower concentrations (<2 mg As·L-1), As stimulated the growth of maize seedlings, and increased the plant height, taproot length, and biomass accumulation significantly; at higher concentrations (>4 mg As·L-1), As inhibited the seedlings growth severely. At 2 mg As·L-1, the chlorophyll a, b, and a+b contents reached their peaks; but with increasing As concentration, the chlorophyll contents decreased gradually. At 10 mg As·L-1, the destruction of chloroplast structure and the dissolution of thylakoid membrane were observed by electron microscopy. With increasing As concentration, the activities of antioxidant enzymes SOD, POD, and CAT in root increased, and those in leaf reached the maximum at 8 mg As·L-1. The sensibility of the enzymes in leaf to As stress was in the order of POD>CAT>SOD. Correlation analysis showed that the contents of MDA, soluble sugar, and soluble protein were positively correlated with As concentration. High concentration As inhibited the absorption of P,K, Ca, Fe and other elements obviously. And comparing with shoot, root was more sensitive to As stress. The growth indices of root could be more available to be used as the indicators of plant arsenic toxicity.
    Effects of winter cover crop on methane and nitrous oxide emission from paddy field.
    2010, 21(12):  3191-3199. 
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    Static chamber-GC technique was employed to study the effects of different treatment winter cover crops, including no-tillage and directly sowing ryegrass (T1), no0tillage and directly sowing Chinese milk vetch (T2), tillage and transplanting rape (T3), notillage and directly sowing rape (T4), and fallowing (CK), on the CH4 and N2Oemission from double cropping rice paddy field. During the growth period of test winter cover crops, the CH4 and N2O emission in treatments T1-T4 was significantly higher than that in CK (P<0.01). Treatments T1and T3not only had the largest CH4 emission(0.60 and 0.88 g·m-2), but also had the largest N2O emission (0.20 and 0.23 g·m-2, respectively). After the winter cover crops returned to field, the CH4 emission from early and late rice fields in treatments T1T2T3, andT4was larger than that in CK. In early rice field, treatments T1 and T2had the largest CH4emission (21.70 and 20.75 g·m-2); while in late rice field, treatments T3 and T4had the largest one (58.90 and 54.51 g·m-2, respectively). Treatments T1-T4also had larger N2O emission from early and late rice fields than the CK did. The N2Oemission from early rice field in treatments T1, T2, T3, andT4 was increased by 53.7%, 12.2%, 46.3%, and 29.3%, and that from late rice field in corresponding treatments was increased by 28.6%, 3.8%, 34.3%, and 27.6%, respectively, compared with CK.
    N2Oand CH4emission from Japan rice fields under different long-term fertilization patterns and its environmental impact..
    2010, 21(12):  3200-3206. 
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    This study intended to investigate the greenhouse gases emission from Japan single cropping paddy fields after 75-year continuous application of ammonium sulfate, composted rice straw with soybean cake, and fresh clover, as well as the environmental impact of the emission. During this long period, field management remained constant in terms of rice cultivation density, irrigation, and equivalent net N fertilization. No significant differences were observed in N2Oemission among the fertilization treatments, but the CH4emission differed significantly between organic amendment and ammonium sulfate application, indicating that long-term organic fertilization didn’t increase N2O emission but promoted CH4emission. The cumulative global warming potential (GWP) of the CH4and N2Ofrom the paddy ecosystem was the greatest (310.7 g CO2e·m-2) under fresh clover application, followed by composted rice straw plus soybean cake addition (151 g CO2e·m-2), and the least (60.6 g CO2e·m-2) under ammonium sulfate application. This study showed that for paddy system, it was CH4 instead of N2Othe major factor affecting global warming, and thereby,to control and reduce the CH4 emission from paddy system would be the core in mitigating greenhouse gases emission from paddy field. Long-term consecutive application of composted rice straw plus soybean cake could increase soil organic matter, improve soil fertility, promote rice high-yielding, and as well, mitigate CH4 emission, being the recommendable paddy rice production mode in practice.
    Transformation of exogenous dimethyl arsenic in soil.
    2010, 21(12):  3207-3211. 
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    A pot experiment was conducted to study the speciation transformation of exogenous dimethyl arsenic (DMA) in soil. The added DMA was mainly transformed into arsenate [As(V)], accompanied with a small amount of monomethyl arsenic (MMA). When the concentration of added DMA was 30 mg·kg-1, the transformation rate was the highest, being 6.71%, 8.11%, 11.33%, and 19.32% when the cultivation time was 10, 15, 30, and 40 days, respectively. With increasing concentration of added DMA, soil soluble arsenic (AE-As) had an increasing trend, but decreased as the cultivation time increased. Comparing with CK, the addition of DMA increased the concentrations of soil arsenic bounded to aluminum (Al-As), iron (Fe-As), calcium (Ca-As), which was possibly  due to the adsorption or fixation of added DMA and its transformation products by the oxides or hydroxides of soil aluminum, iron, and calcium.
    Transformation of different exogenous arsenic forms in soil under aerobic condition.
    2010, 21(12):  3212-3216. 
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    An incubation test was conducted to study the transformation of exogenous dimethylarsenic acid (DMA), monomethylarsenic acid (MMA), and arsenate [As(V)] in soil under the condition of 35% of  water-holding capacity. After added into soil, the concentrations of test arsenic forms all showed a decreasing trend with time. The DMA and MMA were mainly demethylated, and after 120 days incubation at constant temperature and humidity, transformed into As(V). A small amount of MMA was detected in the treatment with added DMA on the 120th day of incubation, and a small amount of DMA was detected in the treatment with added MMA during the period of 7-60 days incubation. By the end of the incubation test, the concentrations of added DMA and MMA in soil decreased significantly (P<0.01), with the decrement being 99.5% and 94.3% and the concentration of transformed As(V) increased by 4.61 and 5.15 times, respectively. Comparing with DMA and MMA, the As(V) after added into soil had less form transformation.
    Interactions between natural vegetation succession and waste residue in lead-zinc tailings deposited sites.
    2010, 21(12):  3217-3224. 
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    Natural vegetation succession process and related mechanism is one of the important research contents in ecological restoration of abandoned mining land. Taking 4 lead-zinc tailings deposited sites with the recovery time being about 10 years, 20 years, 30 years, and over 40 years under similar site conditions in northwest Guizhou Province as study areas, this paper studied the interactions between the natural vegetation succession and the physicochemical properties of waste residue. The results showed that with the increasing dumping time of the waste residue, the nutritional conditions of base material improved significantly,  the total N, P, and K contents and the pH value increased, while the EC, bulk density, and especially, available lead and cadmium contents decreased. Meanwhile, the plant community species richness (S), diversity index (H), and
    evenness (J) increased correspondingly with increasing recovery time. The composition of plant communities was dominated by perennial herbaceous. In the first 20 years of recovery, the vegetation succession process was very slow, but after 30- and 40-year recovery, the vegetation coverage reached 53% and 87%, respectively. Canonical correlation analysis showed that there were significant correlations between base material properties and species diversity, and the canonical variables were the total N, P, and K contents of base material. The species diversity index was significantly negatively correlated with the available Pb and Cd contents of base material. The natural vegetation succession process in the study areas accelerated after 30 years of recovery, and the limiting factors of vegetation recovery were the nutrient deficiency and the high availability of Pb and Cd in base material.
    High arsenic- tolerant fungi: Their isolation and tolerant ability.
    2010, 21(12):  3225-3230. 
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    A total of thirteen fungal strains with higher arsenic (As)- tolerance ability were isolated from six As-contaminated soil samples collected from the mining areas of Shimen County and Chenzhou City in Hunan Province. Among the strains isolated, Penicillin janthinellum, Fusarium oxysporum, and Trichoderma asperellum had the highest As-tolerance ability, based on the morphological identification and phylogenetic analysis. Culture experiment showed that on the solid plates with 30000, 30000, and 20000 mg·L-1 of As, P. janthinellum, F. oxysporum, and T. asperellum had a better colony growth, and after cultured in the liquid medium with 0-50, 0-50, and 0-80 mg·L-1 of As for 2 days, respectively, the dry mycelia masses of the three strains all increased with increasing As concentration. When the As concentration reached 50, 50, and 80 mg·L-1, respectively, the fungal biomass of F. oxysporum, T. asperellum, and P. janthinellum increased significantly, compared with CK. High concentration As had no significant effects on the sporalation of the three fungal strains.
    Differential protein analysis on the root response of rice with high phosphorous uptake efficiency to low phosphorous stress.
    2010, 21(12):  3231-3238. 
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    A comparative proteomics analysis was performed to identify the molecular response of a rice cultivar (Oryza sative cv. ‘IRRI71331’) with high phosphorous (P) uptake efficiency to low P stress. The hydroponically grown rice plants were provided with two levels of P (0.5 mg·L-1 and 10 mg·L-1) supplied in quarter strength Kimura solution, and the root total proteins extracted on the 3rd and 6th day of treatments were separated by two-dimensional gel electrophoresis (2-DE). Comparing with the control (10 mg·L-1 of P), a total of 29 protein spots under low P stress (0.5 mg·L-1) showed differences in their relative abundance, among which, 17 were higher, 11 were lower, and 1 was novel on the 3rd day, and 8 were induced, 19 were suppressed, 1 was disappeared, and 1 had no obvious change on the 6th day. Ten differentially expressed protein spots were identified by MALDI-TOF/MS, and searched in protein databases. According to the putative functions, the identified proteins were classified into four groups, i.e., signal transduction (glycine-rich RNA-binding protein, phosphate starvation response regulator-like), gene expression (putative pre-mRNA splicing factor, putative AAA-metalloprotease), metabolism (adenylosuccinate lyase, serpin, S-adenosylmethionine synthetase, MYB transcription factor-like protein), and ion transport (cation-transporting ATPase, sarcoplasmic reticulum protein). The identified proteins were involved in various physiological responses to enhance stress resistance, such as signal recognition and transduction, RNA cleavage, degradation of denatured protein, and ion transportation and cellular ion balance. The serine protease inhibitor and S-adenosylmethionine synthetase and the MYB transcription factor-like protein, which were the key proteins associated with P deficiency- tolerance of other species, were affected by the same stress for rice. The results indicated that the tolerance to low P stress was controlled by a complex signal transduction and metabolism regulation network in rice root system.
    Population genetic structure of Beauveria bassiana from south and southwest Anhui sericultural regions: ISSR analysis.
    2010, 21(12):  3239-3247. 
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    White muscardine caused by Beauveria bassiana is an important factor affecting sericulture. In the present study, a total of 124 B. bassiana isolates
    were obtained from the silkworm cadavers, rearing rooms and appliances, surrounding mulberry orchards, pine plantations, and croplands in Jingxian County of south Anhui and Qishan County of southwest Anhui. Together with the mass production strains, the isolates were analyzed for population genetic structure by ISSR markers to trace the origin and the spreading track of the muscardine. The results showed that the two B. bassiana populations in Jingxian County and Qishan County were heterogenic, being monophyletic in Jingxian and polyphyletic in Qishan. Both the Jingxian population and the Qianshan predominant subpopulation were characterized typically by enzootic nature, i.e., low incidence and frequent occurrence, but the Qianshan non-predominant subpopulation could spread among some alternate hosts outside the rearing rooms. The groups prevailing in
    pine caterpillar populations in the pine plantations of Qianshan and Jingxian, the production strains, and the epizootic strain prevailing in surrounding mantids were all not associated to the silkworm muscardine, displaying safety to sericulture.
    Seasonal changes of fish species composition and diversity in mudflat wetlands of Hangzhou Bay.
    2010, 21(12):  3248-3254. 
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    In order to understand the spatiotemporal variation of fish species composition and biodiversity in the mudflat wetlands of Hangzhou Bay, thirty six surveys were conducted in the mudflat area, inning area, and aquaculture area in the south bank of the Bay in March (early spring), May (spring), July (summer), and October (autumn), 2009. A total of 41 species belonging to 9 orders and 16 families were observed, among which, Cyprinid had the largest species number (14 species, 33.3% of the total), followed by Gobiidae (8 species, 19.1%). According to the lifestyle of fish, these 41 species could be divided into five ecological types, i.e., freshwater type (21 species), brackish-water type (16 species), inshore type (2 species), anadromous type (Coilia ectenes), and catadromios type (Anguilla japonica). The fish abundance was the highest (54.5 fish per net) in summer, followed by in spring and autumn, and the lowest (17.7 fish per net) in early spring. In the three habitats, mudflat area and inning area had the similar seasonal change of fish abundance, i.e., the lowest in early spring, the highest in summer, and then decreased in autumn. Only two or three species were the dominant species in different seasons. In mudflat area, the dominant species were Mugil cephalus and Liza carinatus; while in inning and aquaculture areas, the dominant species were Carassius auratus, Hemiculter leucisculus, and Pseudorasbora parva. The values of Margalef’s richness index (D), Pielou’s evenness index (J), and Shannon index (H) were lower in March than in other months, but had no significant differences among May, July, and October (P>0.05). The H value ranged in 0.27-2.13, being the lowest in March and higher in May and October (1.66 and 1.63, respectively). Overall, the fish abundance and biodiversity in the mudflat wetlands of Hangzhou Bay had apparent seasonal changes.
    Research progress in water use efficiency of plants under global climate change.
    2010, 21(12):  3255-3265. 
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    Global climate change is one of the most concerned environmental problems in the world since the 1980s, giving significant effects on the  plant
    productivity and the water transport and use patterns. These effects would be reflected in the water use efficiency (WUE) of individual plants, communities, and ecosystems, and ultimately, in the vegetation distribution pattern, species composition, and ecosystem structure. To study the WUE of plants would help to the understanding and forecasting of the responses of terrestrial vegetation to global climate change, and to the adoption of adaptive strategies. This paper introduced the concept of plant WUE and the corresponding measurement techniques at the scales of leaf, individual plant, community, and ecosystem, and reviewed the research progress in the effects of important climatic factors such as elevated atmospheric CO2 concentration, precipitation pattern, nitrogen deposition, and their combination on the plant WUE, as well as the variation characteristics of plant WUE and the adaptive survival strategies of plants under different site conditions. Some problems related to plant WUE research were pointed out, and the future research directions in the context of global climate change were prospected.
    Action mechanisms of microorganisms on arsenic and the feasibility of utilizing fungi in remediation of arsenic-contaminated soil.
    2010, 21(12):  3266-3272. 
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    Utilizing fungi to remediate arsenic-contaminated soil and water body has a great potential, which has been focused and highlighted in environmental sciences. Though the arsenic in environment can not be biodegraded as organic contaminants, its bioavailability can be affected by microorganisms via the processes oxidation/reduction, absorption/desorption, methylation/demethylation, and precipitation/dissolution, etc., and thereby, its toxicity could be reduced, and the arsenic-contaminated environment could be remediated. This paper introduced the action mechanisms of microorganisms on arsenic, summarized the research progress in the arsenic bioaccumulation and bio-volatilization by fungi, and discussed the feasibility of utilizing fungi in the remediation of arsenic-contaminated soil, aimed to provide theoretical reference for the bioremediation strategies of arsenic-contaminated soils.
    Microbial source tracking of water fecal pollution: A review.
    2010, 21(12):  3273-3281. 
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    Livestock feces and domestic sewage are the one of the main factors inducing water pollution, while the identification of the pollution source is particularly important in pollution control and management. Because of this, microbial source tracking (MST) has recently been paid more and more attention by the related researchers around the world. In this paper, the research progress of two types of MST methods, their advantages and disadvantages, and existing problems in application were reviewed and discussed. It was considered that in the library- and culture-dependent MST methods, PCR genotyping based on repetitive sequences was most practicable, while in the library- and culture-independent MST methods, PCR-DGGE based on the gene of specificity in Escherichia coli had a very glaring sight. Future researches should be more focused on the library- and culture-independent MST, and the combination of library- and culture-dependent MST with library- and culture-independent MST could make the tracking results more credible.
    Effects of exogenous NO3- on cherry root function and enzyme activities related to nitrogen metabolism under hypoxia stress.
    2010, 21(12):  3282-3286. 
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    A water culture experiment with controlled dissolved oxygen concentration was conducted to explore the effects of exogenous NO3- on the root function and enzyme activities related to nitrogen metabolism of cherry (Prunun cerasus × P. canescens) seedlings under hypoxia stress. Comparing with the control (7.5 mmol NO3-·L-1), treatments 15  and 22.5 mmolNO3-·L-1 made the materials for plant metabolism abundant, ensured the synthesis of enzyme proteins, increased root activity, maintained root respiration, improved the activities of enzymes related to nitrogen metabolism, such as nitrate reductase (NR), glutamine synthethase (GS), and glutamate dehydrogenase (NADH-GDH) in roots, and thereby, supplied enough energy for root respir
    ation and NAD+ to glycolytic pathway, ensured electron transfer, and avoid ammonium toxicity under hypoxia stress. As a result, the injury of hypoxia stress to cherry plant was alleviated. Applying NO3-· at the concentration of 22.5 mmol·L-1 was more advisable. However, NO3-· deficiency (0 mmol·L-1) showed opposite results. The above results suggested that applying exogenousNO3-· to growth medium could regulate cherry root function and nitrogen metabolism, and antagonize the damage of hypoxia stress on cherry roots.