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    20 April 2010, Volume 21 Issue 04
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    Articles
    Spatiotemporal patterns and driving factors of grassland fire on Mongolian Plateau.
    2010, 21(04):  807-813. 
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    By using GIS spatial analysis method and L3JRC remote sensing data, the spatiotemporal patterns of grassland fire on the Mongolian Plateau in 2000-2007 were examined, and the difference in the grassland fire activities between Inner Mongolia and Mongolia was compared. The effects of vegetation, climate, and human disturbance on the grassland fire were also analyzed. There existed significant difference (P<0.001) in the burned area ratio among three vegetation types, and decreased in the order of meadow steppe > typical steppe > desert steppe. The grasslands in Mongolia had significantly higher burned area ratio than those in Inner Mongolia (P<0.001), and the fire frequency had the same pattern with the burned area ratio. The fire activity differed significantly among years. The burned area ratio was negatively correlated with the annual precipitation in meadow steppe (r2=-0.54, P<0.05) and typical steppe (r2=-0.61, P<0.05). Fire activity also showed monthly variation, occurring mostly in spring and autumn when the weather was dry and windy. It was found that Inner Mongolia had much higher human population and livestock density but lower burned area ratio than Mongolia, suggesting that human disturbance, overgrazing in particular, was the major factor inducing the different patterns of grassland fire between Inner Mongolia and Mongolia.
    Effects of grassland afforestation with Mongolian pine on soil chemical and biological properties in Keerqin Sandy Land.
    2010, 21(04):  814-820. 
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    Taking one grassland and 15-, 24-, and 30 years old Mongolian pine (Pinus sylvestris var. mongolica) plantations in the southeast of Keerqin Sandy Land as test objects, this paper studied the effects of grassland afforestation on the soil chemical and biological properties, including pH value, C, N, and P concentration, inorganic N concentration, C and N mineralization rates, microbial biomass C, and enzyme activities. At the early stage of afforestation, the concentration of soil C, N, and P decreased; but with increasing stand age, they recovered gradually. Compared with those in grassland, the soil C, N, and P concentration in 24 years old plantation decreased by 29%, 34%, and 33%, respectively, but the soil C and N concentration in 30 years old plantation had less difference. Afforestation led to an increase of soil NH4+-N concentration and a decrease of soil NO3-N concentration, but had less effects on the soil N mineralization and nitrification rates. The soil C mineralization rate was decreased in the order of 24 years old plantation >30 years old plantation > grassland >15 years old plantation. Soil microbial biomass C and invertase activity decreased at the early stage of afforestation, but recovered with increasing stand age. After afforestation, soil urease activity had less change, but soil catalase activity increased gradually. Our results indicated that in Keerqin Sandy Land, grassland afforestation with Mongolian pine had significant effects on the soil chemical and biological properties, and the effects differed with stand age.
    Effects of light environment on Juglans mandshurica seedlings growth and photosynthesis.
    2010, 21(04):  821-826. 
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    In order to understand the light requirement and adaptability of Juglans mandshurica seedlings, two-year-old J. mandshurica seedlings were grown under four light regimes (100%, 60%, 30%, and 15% of natural irradiance). After 1-year adaptation, the seasonal variations of the seedlings photosynthetic variables were measured by a Li-6400 portable photosynthesis system. The J. mandshurica seedlings were insensitive to the changes of light environment in spring, but their maximum net photosynthetic rate, maximum carboxylation rate, and maximum electron transport rate increased significantly with increasing light intensity in summer and autumn (P<0.05). The light saturation point declined with decreasing light intensity (P<0.05), but the apparent quantum yield, dark respiration rate, and light compensation point under different light environments had no significant changes. The relative growth rate under 100% and 60% of natural irradiance had no significant difference (P>0.05), but declined significantly in the order of 60%> 30％> 15% of natural irradiance (P<0.05). These results indicated that J. mandshurica seedlings had the maximum relative growth rate under 100% and 60% of natural irradiances, and could tolerate 15%-30% of natural irradiance by reducing light saturation point and carbon accumulation, exhibiting strong adaptability and plasticity to light environment.
    Distribution pattern of Haloxylon ammodendron population based on Ripley’s K(r) function and fractal dimension.
    2010, 21(04):  827-835. 
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    By using Ripley’s K(r) function and fractal dimension, this paper studied the spatial pattern and fractal characteristics of four ecotypes Haloxylon ammodendron population at different development stages in Gurbantonggut desert. Of the four ecotypes, soil ecotype clumped in 1-18 m scale, while sand, saline soil and gravel ecotypes clumped in all scales, suggesting that desert plant could adapt a habitat via clumping. The spatial pattern of H. ammodendron population differed with its development stage. Seedlings and saplings clumped, while adult trees showed random distribution. Compared with Ripley’s K(r) function, correlation dimension could reflect the ability of spatial occupation, but couldn’t directly reflect the clump or not clump in arid area. Moreover, the dimension was susceptible to the number and size of H. ammodendron.
    Water use strategy of Ficus tinctoria in tropical rainforest region of Xishuangbanna, Southwestern China.
    2010, 21(04):  836-842. 
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    Based on the measurement of the stable isotope ratios of hydrogen and oxygen in soil, fog, rain, and plant non-photosynthetic tissues, as well as the gravimetric soil water content, soil water potential, and leaf water potential, this paper studied the water use strategy of F. tinctoria at its different life stages in Xishuangbanna of Southwestern China. The water potential in shallow soil layer (10-50 cm) had a greater change between hot-dry season and foggy season, whereas that in deeper soil layer (51-120 cm) had less change during the seasons. No significant difference was observed in the soil water content between foggy season and hot-dry season. The leaf water potential at predawn and midday varied with life stage. From the measurement of the stable isotope ratios and other parameters, it was found that shallow soil water was the main water source for F. tinctoria, and F. tinctoria had different water use strategy at its different life stages.
    Maximizing empower of Spartina alterniflora community.
    2010, 21(04):  843-848. 
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    When a new plant species is introduced to a new district, its disturbance could alter the structure of original ecosystem, resulting in the formation  of a distinctive self-organized ecosystem to develop the maximizing empower under the new situation. In this paper, an emergy analysis method was made on the two ecosystems Spartina alterniflora salt marsh and mudflat in North Jiangsu. Compared  with the mudflat, S. alterniflora ecosystem had a 1.52E+18 sej higher annual total emergy output, 4.72 times of emergy density, and about 5 times of  base emergy yield ratio. S. alterniflora ecosystem could use the energy more efficiently to increase its emergy storage and to realize it self’s empower maximizing. After invading into a tidal flat ecosystem,  S. alterniflora via self organization could promote the ecosystem to achieve empower maximizing, and to full play its ecological services. However, too fast propagation and  spread could induce a series of negative effects, such as inhibiting native plants, trenching on sea-route, and endangering the seashells breeding, etc.
    Spatial heterogeneity of surface soil moisture in a broad-leaved Korean pine forest in Changbai Mountains based on geostatistic analysis.
    2010, 21(04):  849-855. 
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    By the methods of geostatistics, this paper studied the spatial heterogeneity of surface soil moisture in a broad-leaved Korean pine forest in Changbai Mountains. Three sampling plots sized 50 m×50 m were installed, and the moisture content in 0-7.5 cm soil layer was measured with a time domain reflectometry. The coefficient of variation of the surface soil moisture was 24.32% in plot 1, 24.11% in plot 2, and 23.60% in plot 3, suggesting a moderate variability. The variogram of the surface soil moisture could be well fitted by spherical model, and had a higher spatial heterogeneity, which mainly came from spatial autocorrelation. The structural ratio of surface soil moisture was 57.9% in plot 1, 83.3% in plot 2, and 90% in plot 3, and the regressed range (distance beyond which samples were spatial independent, an indicator of patch size) was 5.5-13.1 m, being consistent with the results from Bayesian method. Through Kriging interpolation, the surface soil moisture content was 49.3% in plot 1, 52.8% in plot 2, and 42.6% in plot 3.
    Evolvement of landscape pattern in coastal peri-urban area: A case study of Jimei District, Xiamen City.
    2010, 21(04):  856-862. 
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    Based on the 1987-2007 Landsat TM/ETM+ images of Jimei District in Xiamen City, and through the analysis of landscape indices on both patch- and landscape scales, this paper quantitatively studied the evolvement and spatiotemporal characteristics of the unique landscape pattern in the coastal peri-urban area. The evolvement of the landscape pattern in the area had the characters of rapid, instable, heterogeneous, and transitional. In 1987-2007, the land area for urban construction increased from 2.7 km2 to 29.1 km2, with an average annual growth rate of 13%, but still was not the predominant landscape. The rapid expansion of urban construction land was mainly through occupying farmland and absorbing rural settlements, which showed the character of “enclave” and resulted in a complex space form. In the same period, the land area for rural construction increased by 2.3 times, with an average annual growth rate of 6.2%, and the expansion of the rural construction land had the characters of out-of-order and dispersive. 42% of the farmland was depleted by the urban and rural sprawl, resulting in its fragmentation. Under the effects of urbanization, the overall landscape pattern of the peri-urban area tended to be fragmentized and heterogeneous, because of the rapid and complicated landscape change.
    Landscape centrality and its applications in ecological network planning and management.
    2010, 21(04):  863-872. 
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    Coherent ecological network (EN) construction has been considered as an important landscape planning strategy for biodiversity conservation, eco-environmental safety management, and resources protection of recreation, history and culture. Its planning and management attract extensive attentions from ordinary people to managers. To identify the key landscape elements is the keystone and the difficulty in EN planning and management. In order to solve this problem, the concept landscape centrality and its measurement were put forward in this paper, based on graph theory and network analysis theory, with its application aspects and framework discussed. It was considered that though the concept landscape centrality could supply a new approach to solve the problems in identifying key landscape elements and building coherent EN, further studies should be made on the ecological significance of centrality indices, analysis of experimental data, and development of simple and universal software, aimed to validate and improve this approach.
    Prediction of landscape patterns in Ili River Delta based on CA_Markov model.
    2010, 21(04):  873-882. 
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    Based on the remote sensing and hydrologic data and in combining with the characteristics of arid area, a landscape classification system for Ili River Delta was established. In the meantime, by the methods of quantitative analysis in landscape ecology and the simulation method with CA_Markov model, the landscape change pattern in the Delta from 1975 to 2007 and the scenarios simulation landscape pattern in 2020 were analyzed. Under the effects of anthropogenic activities and environmental factors, the landscape change pattern in 1975-2007 presented definite periodicity and instability. In 1990-2007, the landscape change accorded with the applied conditions of CA_Markov model; in 2020, the predicated landscape pattern showed severe patch fragmentation, the landscape connectivity tended to be weakened, and the spatiotemporal change patterns of the landscapes closely related to water, such as lake, marsh, and floodplain, were of great uncertainty. There was a significant differentiation between the predicated landscape patterns in 2020 based on the 1990-2000 and 2000-2007 probabilistic transfer matrixes. The variation degrees and expression forms of different landscapes also differed, due to the discrepancy and instability of natural conditions, as well as the different change ways and directions of landscape types in 1900-2000 and 2000-2007.
    Spatial pattern of surface soil organic matter |based on remotely sensed multispectral image.
    2010, 21(04):  883-888. 
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    Remotely sensed multispectral LandSat TM image was used to analyze the spatial pattern of surface soil organic matter across the cropland in Fuxin Town of Liaoning Province. The proper bands of the TM image that correlated with the distribution of surface soil organic matter were selected, and the quantitative relationships between surface soil organic matter and the digital number (DN) values of bands TM 1, TM 2, TM 3, TM 4, TM 5, TM 6, and TM 7 were analyzed and determined, which could be applied to establish a prediction model of surface soil organic matter. It was shown that the surface soil organic matter in study area had a strong negative correlation with the DN values of TM 4 and TM 5 (r=-0.617 and -0.623, P<0.001), and an inverse second order polynomial regression with the DN values of TM 3 and TM 5 (R2=09134, P<0.001). The regression model using the DN values of TM 3 and TM 5 could make a reliable prediction of the spatial pattern of surface soil organic matter (R2=0.9151, P<0.001). Across the study area, the cropland with soil organic matter content less than 10 g·kg-1 was mainly distributed in the zones at hill foot, while that with surface soil organic matter content usually more than 10 g·kg-1 and partly reached 15-20 g·kg-1 was in flat zone.
    Effects of seasonal freeze-thaw cycle on soil aggregate characters in typical phaeozem region of Northeast China.
    2010, 21(04):  889-894. 
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    Taking the cropland soil in typical phaeozem region of Northeast China as test object, this paper analyzed its dry-sieved and water-stable aggregates composition, disruption rate (PAD0.25, PAD1.0), mean mass diameter (Dmm), mean mass soil surface area (SAmm), and fractal dimension (D) under different water supplement and different frequency and rate of freeze-thaw cycle, aimed to study the effects of seasonal freeze-thaw cycle on the top soil aggregate characters in the region. No water supplement plus no freeze-thaw cycle and no water supplement plus freeze-thaw cycle increased the amounts of >5 mm dry-sieved and >0.25  mm water-stable aggregates significantly, and the Dmm of the aggregates by 7.98%-29.41% and 36.11%-44.44%, respectively. The measurement of SAmm and D also indicated the promotion of the aggregation of macroaggregates. However, smaller water supplement plus freeze-thaw cycle and seasonal freeze-thaw cycle increased the amounts of <2 mm dry-sieved aggregates and 0.25-1 mm water-stable aggregates significantly, accelerated the disruption of air-dried aggregates, and decreased the SAmm and D of water-stable aggregates by 10.88%-25.52% and 1.02%-3.40%, respectively, indicating that aggregation was somewhat promoted. After seasonal freeze-thaw cycle, the PAD0.25 decreased by 33.45% (P<0.05) but PAD1.0 had less change, suggesting that the seasonal freeze-thaw cycle in typical phaeozem region did not weaken soil splash-resistibility, while strengthened the water-stability of soil aggregates.
    Soil physical and chemical properties and root distribution in high yielding spring maize fields in Yulin, Shaanxi Province.
    2010, 21(04):  895-900. 
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    An investigation was made on the yield component, dry matter allocation, root distribution in 0-100 cm soil layer, and soil physical and chemical properties in two high yielding (>19500 kg·hm-2) spring maize fields of Yulin, Shaanxi Province. In the two fields, the planting density was from 105000 plants·hm-2 to 123000 plants·hm-2, spike rate was from 97.7% to 102.2%, 1000-grain weight was >320 g, and the dry matter allocation in ears occupied 60.2%-65.5% of the total. The average bulk density in 0-100 cm soil layer was from 1.28 g·cm-3 to 1.33 g·cm-3, and the soil bulk density, porosity, and field water-holding capacity along the profile all changed in M type. Maize roots were mainly distributed in 0-60 cm soil layer, and those in 0-20 cm and 20-60 cm accounted for 64.8%-72.1% and 23.30%-28.17% of the total, respectively. There was a close relationship between root distribution and soil physical-chemical properties. Root dry mass in 0-20 cm soil layer had a significant positive correlation with soil organic matter, total nitrogen, and total phosphorus, while that in 20-60 cm soil layer was significantly correlated with soil bulk density and field water-holding capacity. Therefore, to select soils with good permeability and high maintenance capacity of water and nutrients would be the key in obtaining high maize yield.
    Spatial variability of soil N, P, and K in main production area of Castanea mollissima.
    2010, 21(04):  901-907. 
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    By using the methods of classic statistics in combining with geo-statistics, this paper analyzed the spatial variability of soil N, P, and K in the main production area of Jingdong chestnut,  Qianxi County of Hebei Province. In the study area, the contents of soil total N, P, and K and soil available N and K were lower, but the available P content in topsoil was higher. The soil N, P, and K had a medium variability of distribution, and soil P had the largest coefficient of variation. In topsoil, the distribution of total N and available N fitted Gaussian model, and their spatial variability was mainly affected by structure factors. The distribution of soil total K and available K fitted spherical model and Gaussian model, respectively. The spatial variability of soil total K was co-affected by structure factors and random factors, and had a medium spatial correlation; while the spatial variability of soil available K was mainly affected by structure factors, and had a strong spatial correlation. At county scale, soil N and K contents were higher in the south and northwest than in the middle and northeast, soil total P content was higher in the north, and soil available P content was higher in the south. Soil total N and K had significant positive correlations with soil available N and K; while soil total P had no significant correlation with soil available P.
    Effects and action mechanisms of different water management modes on rice Cd absorption and accumulation.
    2010, 21(04):  908-914. 
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    Taking Cd polluted reddish yellow paddy soil (RYPS) and alluvial loamy paddy soil (ALPS) as test objects, pot experiments were conducted to study the effects of different water management modes, including whole growth season flooding (WF), draining and sunning field at tillering stage (TP), draining and sunning field at milk stage (MP), draining and sunning field at tillering and milk stages (TMP), and wetting irrigation (WI), on the Cd absorption and accumulation by rice. For the two test soils, their Fe2+ content was the highest in treatment WF and the lowest in treatment TMP. Compared with TMP, treatment WF increased the Fe2+ content in ALPS by 585.4% and that in RYPS by 1316.3%. The contents of available S and available Cd in the two soils were all in the order of WF<TP<MP<WI<TMP. Comparing with TMP, treatment WF decreased the available S and available Cd contents in ALPS by 96.4% and 70.1% (P<0.01), and those in RYPS by 55.5%  and 54.1% (P<0.01), respectively. On the two soils, WF and MP had a relatively higher rice yield than other treatments. The Cd content in rice stem and leaf and in brown rice followed the sequence of WF<MP<TP<WI<TMP, and was decreased by 74.1%  and 57.5% (P<0.01) in treatment WF on ALPS, and by 55.6%  and 43.6% (P<0.01) in treatment WF on RYPS, respectively, compared with those in treatment TMP. Besides the available Cd content of the two soils, water management modes also played important roles in the Cd absorption and accumulation by rice via affecting the soil Fe2+ and available S contents, with the effects being significantly larger on soil available S than on soil Fe2+.
    Effects of different application modes and rates of controlled release urea on fertilizer nitrogen use efficiency and grain yield of summer maize.
    2010, 21(04):  915-920. 
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    A field experiment was conducted to study the effects of different application modes (bottom application and side-dressing) and rates (0，75，  and 150 kg N·hm-2) of controlled release urea on the photosynthetic capability, fertilizer nitrogen use efficiency, and grain yield of maize (Zea mays L.). Compared with conventional urea (U), the controlled release urea (CU) at same application rates increased the leaf photosynthetic rate, chlorophyll content, nitrate reductase activity, and kernel filling rate significantly, and promoted the grain yield by an average of 9.5% (P<0.05). Bottom application of CU induced a 6.2% higher grain yield than side-dressing CU. The average agronomic efficiency (AE) and partial factor productivity (PFP) of CU were 74.5% and 11.0% higher than those of U, and bottom application of CU increased the AE and PFP by 26.8% and 5.7%, respectively, compared with side-dressing CU. Higher application rates of CU improved the photosynthetic capability, and increased the grain yield, AE, and PFP. Bottom application of CU could significantly increase the grain yield, AE, and PFP of maize, compared with side-dressing CU.
    Effects of long-term application of chemical fertilizer, pig manure, and rice straw on chemical and biochemical properties of reddish paddy soil.
    2010, 21(04):  921-929. 
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    In 2005 and 2007, soil samples were collected from a 27-year experimental field in Wangcheng County of Hunan Province to study the effects of long-term application of chemical fertilizers (CF) and their combinations with pig manure (PM) and rice straw (RS) on the chemical and biochemical properties of reddish paddy soil (Typic Haplic-Stagnic Anthrosis). Under the fertilization, soil pH had somewhat decrease, and soil conductivity changed less, compared with those before the experiment was installed. The contents of soil total organic carbon (TOC), total N, available N and P, and microbial biomass C (Cmic) and N (Nmic), soil respiration rate, and activities of soil urease, acid phosphatase, invertase, and dehydrogenase were all higher in treatments CF+PM and CF+RS than in treatments CF and CK, and the Cmic/TOC ratio was higher in treatments CF+PM and CF+RS than in treatment CF. During the study period, applying CF alone induced a lower rice yield than the application of CF plus PM or RS.There were significant positive correlations (P<0.01) between soil biochemical properties and soil TOC and nutrient contents. It was concluded that long-term application of CF combined with PM and RS improved the soil chemical and biochemical properties, being an effective measure to improve the quality and fertility of reddish paddy soil.
    Short term effect of applying organic materials in improving soil fertility of Weibei rainfed highland.
    2010, 21(04):  930-936. 
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    A comprehensive evaluation was made on the effects of applying different organic materials on the soil chemical properties and enzyme activities in Weibei rainfed highland, based on field experiment and laboratory analysis. A total of ten quantitative indices were selected, and factor analysis and minimum Euclidean distance method were employed to evaluate the overall soil fertility. Crop yield was used to verify the evaluation results. Applying organic materials promoted soil fertility and crop yield significantly. Compared with applying chemical fertilizer alone, its combination with straw compost and with organic manure increased the wheat yield by 20.43% and 22.38%, respectively. The soil quality under the combined application of chemical fertilizer with straw compost was the highest, with an integrated score up to 56.53, followed by the combined application of chemical fertilizer with organic manure, and of chemical fertilizer with high amount straw. Therefore, a combined application of chemical fertilizer with straw compost or organic manure could improve the soil fertility significantly, and thereby, increase the crop yield. Using the selected 10 factors and factor analysis to evaluate the quality of soil fertility could accurately reflect the soil fertility level, and predict the soil productivity in the highland.
    Coupling relationship of agricultural eco-economic system in Wuqi County based on structural equation model.
    2010, 21(04):  937-944. 
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    Based on the peasant household investigation in Wuqi County in 2008, the coupling relationship of agricultural eco-economic system in the County was analyzed by using structural equation model. It was shown that agricultural resources and industrial situation had definite effects on the system coupling, with the influence coefficient being 0.14 and 1.00, respectively. There was a negative correlation coefficient (-0.11) between the agricultural resources and industrial situation, suggesting that the industrial development in the City was not based on the effective utilization of agricultural resources, and the agricultural resources hadn’t direct effects on the economic benefit. The direct path coefficient between the industrial situation and economic benefit was -2.95, and the total path coefficient was only 0.23, illustrating that the industrial development in the City was mainly relied on the utilization of other energy and material resources. From the viewpoint of the coupling relationship of the agricultural eco-economic system, it was considered that the current agricultural ecosystem in the County was unstable, and less depended on outside resources. In other words, there was a potential crisis in the process of building and forming a well coupled agricultural eco-economic system. Therefore, this county should improve its utilization of agricultural resources through developing its pasture and forest industries.
    Distribution characteristics of water and salt in a spring wheat soil under brackish water irrigation.
    2010, 21(04):  945-951. 
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    A field experiment was conducted to study the distribution characteristics of water and salt in a spring wheat soil under brackish water irrigation. Three irrigation quota (100%ETc, 80%ETc, and 60%ETc) and three water salinity levels (0.7, 3 and 6 g·L-1) were installed. The results showed that soil water distribution was affected by irrigation quota and soil texture. Sufficient irrigation made the irrigation water stored in deeper soil layers; while insufficient irrigation made the irrigation water more stored in top soil layer. Under the same irrigation quota, the salt accumulation in soil body increased with increasing water salinity; while under the same water salinity, the salt content and salt accumulation depth in soil body increased with increasing irrigation quota. Successive brackish water irrigation in the whole growth period of spring wheat induced soil salinization, and insufficient irrigation made the salt more accumulated in surface soil layer, compared with sufficient irrigation.
    Spatiotemporal distribution of photosynthetically active radiation in rice canopy.
    2010, 21(04):  952-958. 
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    Field experiments were conducted in Nanjing in 2007 and 2008, involving two rice cultivars and three nitrogen application rates. The plant morphology and spatiotemporal distribution of PAR at different canopy heights were measured at filling stage with SunScan canopy analysis system. Nitrogen application rate had significant effects on the plant height, panicle curvature, and leaf angle of rice. The leaf area was greater in mid canopy than in upper and basal canopy. The maximum leaf area index (LAI) layer appeared at 0.60 of relative canopy height. The average PAR transmittance decreased from top to bottom in rice canopy, exhibiting a quick attenuation within the upper and mid canopy and a slow reduction within the basal canopy. In addition, the average PAR transmittance at different canopy heights decreased with increasing nitrogen application rate. The diurnal variation of average PAR transmittance was greater at noon than in the morning and afternoon. With increasing LAI accumulation, the average PAR transmittance at different canopy heights decreased in an exponential pattern. The diurnal variation of population extinction coefficient (K) was smaller at noon than in the morning and afternoon, and the K value was in the range of 0.35-0.50. The 3-dimensional distribution of PAR in rice canopy indicated that the PAR transmittance on horizontal plane was greater, and exhibited much more light flecks in upper and mid canopy than in basal canopy. The PAR density distribution at the same canopy height was non-uniform on the horizontal plane. Higher PAR transmittance, greater diurnal variation of PAR transmittance, and smaller population extinction coefficient were observed for the erect plant type rice cultivar.
    Effects of light quality on the growth and chloroplast ultrastructure of tomato and lettuce seedlings.
    2010, 21(04):  959-965. 
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    By using light emitting diode (LED) to accurately modulate spectral energy distribution, and with fluorescent light as the control, this paper studied the effects of light quality on the growth and chloroplast ultrastructure of tomato and lettuce seedlings. Under red LED, the soluble sugar, starch, and carbohydrate contents of tomato and lettuce seedlings were significantly higher than those under fluorescent light, and the starch grains in chloroplast swelled obviously. Under blue LED, the hypocotyl length of tomato seedlings were restrained remarkably, but the leaf chlorophyll a and carotenoid contents of tomato and lettuce seedlings were increased significantly. Under red + blue LED, the soluble sugar, starch, carbohydrate, and sucrose contents and C/N ratio of lettuce seedlings reached the maximal and were significantly higher than those under red LED, the main root length of the seedlings increased significantly, their leaf chloroplast morphology was normal, granum number increased, stroma lamellae was clear, but the starch grain size was smaller than that under red LED. The results suggested that light quality had remarkable effects on the photomorphogenesis, growth, carbon and nitrogen metabolism, and chloroplast development of plant seedlings. Red LED promoted the accumulation of photosynthates but hindered their transport, while adding appropriate amount of blue LED to red LED could more benefit the accumulation of photosynthates in lettuce seedlings, and promote the seedlings root growth and the export of assimilation products.
    A newly developed blue nitrogen index for estimating canopy leaf nitrogen concentration of rice.
    2010, 21(04):  966-972. 
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    Based on the field experiments with different rice varieties and nitrogen application rates, a comprehensive analysis was made on the quantitative relationships between hyperspectral vegetation indices of rice canopy and its leaf nitrogen concentration (LNC) at different rice growth stages. The wave bands most sensitive to the canopy LNC were in red region (665-675 nm), blue region (490-500 nm), and red edge region (680-760 nm). Within the range of 400-2500 nm, the wave bands showing the best relationships between rice canopy vegetation indices and LNC were 550-600 nm and 500-550 nm in green region, and the ratio index SR(533,565) had the highest value of determination coefficient (R2). However, the spectral parameter established with three wavelengths in blue region, i.e., blue nitrogen index R434/(R496+R401), had a significant linear relationship with the canopy LNC, and made the prediction accuracy of the canopy LNC promoted significantly, compared with SR(533,565). The tests with independent datasets showed that R434/(R496+R401) was a reliable indicator of rice canopy LNC, with the RMSE and RE values between measured and estimated LNC being 9.67% and 8%, respectively. Therefore, the newly developed blue nitrogen index R434/(R496+R401) was recommended as a good indicator of rice canopy LNC.
    Community structure and diversity of butterfly in Mt. Liupanshan National Nature Reserve of Ningxia, China
    2010, 21(04):  973-978. 
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    An investigation was made on the community structure and diversity of butterfly in the Mt. Liupanshan National Nature Reserve of Ningxia. There were 130 species, belonging to 5 families and 68 genera. Nymphalidae had the highest number of genus (33) and species (68), while Papilionidae only had 2 genera and 2 species. Lycaenidae had the highest richness index (1.75) and evenness index (0.84), Nymphalidae had the highest diversity index (3.01), Pieridae had the highest dominance index (0.90), while Papilionidae had the lowest richness index (0.37), diversity index (0.40), and dominance index (0). In the subfamily of Nymphalidae, Satyrinae had the highest number of genera (13) and species (24), Libytheinae only had 1 genus and 1 species, Apaturinae had the highest richness index (1.11) and evenness index (0.84), Limenitinae had the highest diversity index (2.04), and Satyrinae had the highest dominance index (0.96).
    Genetic diversity of native goat breeds in Henan Province.
    2010, 21(04):  979-986. 
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    In this paper, the genetic diversity of five native goat breeds (Niutui, Huai, Henan Dairy, Taihang Black, and Funiu White) in Henan Province was evaluated by using 18 microsatellite loci. For the five goat breeds, the 18 microsatellite loci were all highly polymorphic. The higher polymorphism information content (PIC), higher heterozygosity (Hz), and larger number of alleles suggested the higher genetic diversity, and the greater genetic variation of the breeds. Cluster analysis showed that Niutui goat had a closer relationship with Taihang Black goat, but a relatively far relationship with Henan Dairy goat. The coefficient of genetic differentiation and the genetic distance indicated that the variation mainly existed within the breeds, but small variation also existed among the breeds. In combining with the actual eco-geographic distribution of the five goat breeds, a conservation mode of avoiding inbreeding and implementing selective hybridization was proposed.
    Effects of cadmium on testis spermatocyte apoptosis and epididymis mature spermatozoa quality of mice.
    2010, 21(04):  987-992. 
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    By the method of artificial water contamination, and using transmission electron microscope (TEM) and flow cytometer (FCM), this paper studied the effects of cadmium on the germ cell apoptosis in testis and the quality of mature spermatozoa in epididymis of mice. Compared with that in control group, the amount of the germ cells under apoptosis in experimental groups was remarkably higher, and the ultrastructure of the germ cells showed the phenomena such as mitochondrion vacuole, karyotheca invagination, chromatin margination, and karyopyknosis, indicating that cadmium could easily cause testis spermatocyte apoptosis of mice. The proportion of the germ cells with early apoptosis was significantly higher in experimental groups than in control group, while that of active germ cells was in reverse (P<0.05). In high dosage group (0.10 mmol CdCl2·L-1), the survival rate of germ cells (75.1%) was significantly lower than that in control group and other experimental groups, and the early apoptosis rate of the germ cells (22.6%) was significantly higher than that of the control. The DNA breakage rates of the germ cells in testis and epididymis were significantly higher in high dosage group (18.2% and 26.5%) than in control group (3.3% and 5.6%) (P<0.05), and the amounts of testis germ cells with DNA breakage in experimental groups were lower than those of the epididymis germ cells with DNA breakage. The apoptosis rates of the germ cells in testis and epididymis increased gradually with the increase of cadmium dosage. It was concluded that the dosage of cadmium had definite effects on the apoptosis and DNA damage of mice germ cells.
    Toxicity and field control efficacy of pyriproxyfen and its mixture with organic silica to B-biotype Bemisia tabaci.
    2010, 21(04):  993-999. 
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    Laboratory bioassay and field experiment were conducted to evaluate the toxicity and field control efficacy of pyriproxyfen and its mixture with organosilicon to B-biotype Bemisia tabaci. The laboratory bioassay indicated that pyriproxyfen had strong ovicidal activity against B. tabaci and high activity against B. tabaci nymphs, but had low toxicity to B. tabaci adults. After the adults were exposed to pyriproxyfen-treated eggplant leaves for 48 h, their oviposition on untreated eggplant leaves was not affected, but the egg hatching rate was sharply lowered, suggesting that pyriproxyfen had high transovarial activity. Organosilicon auxiliary agent did not show any synergistic effect when mixed with pyriproxyfen. Field trials showed that pyriproxyfen could effectively control the B. tabaci nymphs on eggplants, but could not effectively control the adults.
    Quantitative changes of phenolic acids in Larix gmelinii needles induced by leaf damage.
    2010, 21(04):  1000-1006. 
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    Phenolic acids are the important secondary metabolites associated with induced plant responses. Taking the Larix gmelinii seedlings with their needles on 4 selected branches being partially cut off or fed by Dendrolimus superans (Lepidoptera: Lasiocampidae) larvae as test objects, this paper quantitatively determined the phenolic acid concentrations in the undamaged needles by using HPLC. One day after 50% of the needles on the branches were cut off or fed by D. superans larvae, the concentrations of benzoic acid, caffeic acid, gallic acid, phenylaetic acid, cinnamic acid, vanillic acid, syringic acid, sylicylic acid, and chlorogenic acid in undamaged needles had significant difference with the control; and one day after 75% of the needles were cut off or fed by D. superans larvae, the concentrations of the 9 phenolic acids and ferulic acid changed significantly. These results implied that cutting off or feeding with 50% or 75% of the needles could cause the concentrations of phenolic acids in needles reach the damage thresholds to induce chemical defense of larch seedlings. On the first day after treatment, the concentrations of caffeic acid, phenylaetic acid, cinnamic acid, vanillic acid, and gallic acid in needles induced by 50% and 75% of cutting were all significantly higher than those induced by larvae feeding; on the 5th day after treatment, the concentrations of these 5 phenolic acids induced by 50% and 75% of cutting were significantly lower than those induced by feeding; while on the 10th day after treatment, the concentrations of the 5 phenolic acids had no significant difference between cutting and feeding. It suggested that the quantitative changes of phenolic acids in larch needles induced by cutting were more rapidly than those induced by feeding, and the induced defense response intensity of phenolic acids was correlative with cutting degree. All of the results showed that it was possible to control the pest damage of L. gmelinii by using appropriate methods to induce the quantitative change of phenolic acids in needles.
    Effects of feeding by Spodoptera litura on the composition and quantity of Bt maize volatiles.
    2010, 21(04):  1007-1013. 
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    By the methods of headspace enrichment and GC-MS, this paper studied the composition and quantity of the volatiles emitted from two transgenic Bt  maize varieties (5422Bt1 and 5422CBCL) and their homologous regular variety (5422) after the feeding by Spodoptera litura. As for the intact plants, the volatiles emitted from variety 5422 were (E)-β-ocimene, linalool, (3E)-4,8-dimethyl-1,3,7-nonatviene (DMNT), and (E)-β-farnesene, those from 5422Bt1 were linalool and DMNT, while 5422CBCL only emitted linalool. After the feeding by S. litura, a total of twelve volatiles including terpenoid, alcohol, ester, and indole were emitted from 5422 and 5422Bt1, and ten volatiles were emitted from 5422CBCL, with a lack of (Z)-3-hexen-1-yl acetate and nerolidol. The kinds and quantities of terpenoids emitted from the test three varieties were increased significantly, with eight kinds increased for varieties 5422 and 5422Bt1, and seven kinds increased for 5422CBCL. The emitted amounts of linalool and DMNT from the Bt maize varieties were
     higher than those from the regular variety, while the emitted amounts of other volatiles were in reverse. Especially for (E)-β-farnesene, its emitted amount from the Bt maize varieties was much lower than that from the regular variety. It was obvious that after the feeding by S. litura, the composition and quantity of the volatiles emitted from the Bt maize varieties differed with those emitted from the regular variety, and there was a difference between varieties 5422Bt1 and 5422CBCL.
    Bacterial community structure in production water from oil reservoirs in Daqing Oilfield.
    2010, 21(04):  1014-1020. 
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    By the methods of molecular biology, this paper studied the bacterial community structure in the production waters from polymer-flooded, water-flooded, and transition zone’s oil reservoirs in Daqing Oilfield of Northeast China. The total DNA was extracted from the three production waters, and the 16S rDNA clone libraries of the waters were constructed. About 200 positive clones were randomly selected from each library, and analyzed with amplified ribosomal DNA restriction analysis (ARDRA). The selected 596 positive clones were clustered into 85 operational taxonomic units (OTUs), with 28 OTUs in polymer-flooded library, 41 in water-flooded library, and 33 in transition zone’s library. Sequences analysis of the libraries showed that the dominant bacterial groups in the production waters were Acinetobacter, Arcobacter, Firmicutes, Pseudomonas, and Sulfurospirillum. Polymer-flooded sample had the simplest bacterial composition, with the dominant (85%) of Acinetobacter, and part (7%) of Pseudomonas. Water-flooded sample was also dominated by Acinetobacter (62%), while Pseudomonas and Sulfurospirillum occupied 20% and 6% of the total, respectively. Different from the former two, the transition zone’s sample was dominated by Arcobacter (50%), followed by Acinetobacter (19%) and Firmicutes (18%).
    Anti-microbial activity of endophytic actinomycetes isolated from Ammodendron bifolium and their antagonism to endophytic bacteria.
    2010, 21(04):  1021-1025. 
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    A total of twelve endophytic actinomycetes and thirty-one endophytic bacteria were isolated from the surface-sterilized Ammodendron bifolium (Pall.) Jakovl roots, and the anti-microbial activity of the endophytic actinomycetes was screened, taking Escherichia coli, Staphylococcus aureus, and Bacillus subtilis as the indicator strains. Three of the 12 isolated endophytic actinomycetes could inhibit the growth of the three indicators, and two did not
    show any anti-bacterial activity. The antagonism of the endophytic actinomycetes against the endophytic bacteria isolated from same plane was significant different. About 44.9% pairing showed inhibiting activity, with the diameters of inhibition zone from 8.25 mm to 28.5 mm, and the main targets were gram negative and bacillus bacteria, while 55.1% pairing did not show exhibiting activity, indicating that the interactions between endophytic actinomycetes and bacteria were quite diversified.
    Effects of sewage sludge application on leaf photosynthesis and plant growth of Buxus microphylla.
    2010, 21(04):  1026-1030. 
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    The application of urban sewage sludge as an organic fertilizer for garden plants has obtained an increasing attention. Taking Buxus microphylla seedlings as test objects, a greenhouse pot experiment was conducted to study the responses of their photosynthetic characteristics and growth to the application of sewage sludge (SS). Five treatments were installed, i.e., low dosage SS (LC), medium dosage SS (MC), high dosage SS (HC), inorganic fertilizers (IF), and control (no application of sewage sludge and inorganic fertilizers, CK). The application of SS increased the chlorophyll and N contents in B. microphylla seedlings leaves, but with the increase of SS dosage, the net photosynthetic rate (Pn) decreased. In August, treatments LC and MC increased the Pn but HC decreased the Pn by 259% and 89%, respectively, compared with IF and CK. In October, treatments LC, MC and HC decreased the Pn, compared with IF, but the Pn in LC was still higher than that of CK. The Pn in treatments MC and HC was lower than that of CK, and the Pn in HC was 48.4% and 29.2% lower than that in IF and CK, respectively. The plant height, basal diameter, and root length were the greatest in treatment IF, followed by in LC. Treatment LC induced the greatest above ground biomass; MC increased the plant height and the above ground biomass, but decreased the basal diameter and root length, compared with CK; while HC seriously restrained the root growth. Our results indicated that the dosage of sewage sludge for B. microphylla seedlings should be lower than 30 t·hm-2.
    Soil pH value and fertility level at various types of slopes in disturbed area of Xiangjiaba hydropower construction.
    2010, 21(04):  1031-1037. 
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    Taking seven types of slopes in the disturbed area of Xiangjiaba construction as test objects, this paper measured their soil pH, and evaluated their soil fertility with standard integrated grade method. The soil at vegetation-growing concrete gunning (VGCG) was weakly alkaline, while the others were acidic at different degree. The soil pH value was decreased in the sequence of VGCG (7.68±0.04)> discarded residue (DR) (6.96±0.02)> framed beams with soil cover (FBSC)(6.93±0.16)> external soil with spray seeding (ESS)(6.75±0.35)> thick layer substrate (TLS)(6.67±0.36)> natural secondary forest (NSF)(5.68±1.25)> natural forest (NF)(4.71±0.23); while the integrated index of soil fertility was in the order of VGCG (3.06±0.02)< TLS(4.06±0.78)< NSF(4.52±0.16)< FBSC(4.62±0.06)< NF(4.62±0.06)< ESS(4.90±0.01)< DR(5.00±0.10). It proved that some artificial additives such as cement, compound fertilizer, and humus had definite positive effects in adjusting soil pH and maintaining soil fertility, being helpful to provide favorable soil condition for plant growth.
    DEM-based ecological purification system analysis and design.
    2010, 21(04):  1038-1042. 
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    By using plot investigation and system simulation methods, and taking a typical complex wetland ecosystem in Liaodong Bay as research object, the organic pollutants purification efficiency of the ecological units was analyzed comprehensively and a pollutants purification capacity estimation model was built correspondingly. Furthermore, an optimal design to the wetland ecosystem based on its DEM (digital elevation model) information was made. The results indicated that the purification ability for CODCr, BOD5 and petroleum were different in each ecological units, which led to different purification loading rate of systems with various components and structures. The original CODCr purification capacity and the removal loading of CODCr in the study area were 188.9 kg·d-1 and 284 g·m-2·d-1, respectively, while they were up to 313.3 kg·d-1 and 4.72 g·m-2·d-1 after the optimal ecological design based on the DEM information, with the purification efficiency being enhanced by nearly 20%.
    Mating capacity of male Macrobrachium rosenbergii with different morphotypes.
    2010, 21(04):  1043-1048. 
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    From the viewpoint of behavioral ecology, a pilot study was made on the mating capacity of male Macrobrachium rosenbergii with different morphotyp
    es (blue claw, BC; orange claw, OC; runt or small male, SM) native to the Pusur River in Chalna County of Khulna Division, Bangladesh. No significant differences were observed in the mating behavioral modes among the male morphotypes, but the time invested in such typical mating behaviors as pre-/postcopulatory mate-guard and copulation/spermatophore transfer for BC, OC and SM had distinct difference. BC spent much less time than OC or SM on precopulatory guard (PG) and spermatophore transmission (ST), but much more time on post-copulatory guard. SM spent the longest time on PG and ST, and the shortest time on postcopulatory guard. The average frequencies of successive copulation in 120 h were respectively 4.6, 2.2, and 1.3 at the sex ratio of 8∶1 (♀∶♂) in BC, OC and SM when the body mass of the females was 80 percent of the males. BC possessed much stronger capacity of successive copulation. The mating capacity of male M. rosenbergii was not only related to its own body mass, but also related to the body mass of female M. rosenbergii. Only when the males and females matched to some extent in their body mass, could the copulation be guaranteed in success. Otherwise, false copulation would occur.
    Effects of spatiotemporal and environmental factors on the fishing ground of Trachurus murphyi in Southeast Pacific Ocean based on generalized additive model.
    2010, 21(04):  1049-1055. 
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    Based on the 2001-2007 Chilean jack mackerel (Trachurus murphyi) fishing data from Chinese vessels, as well as the spatiotemporal factors and the environmental factors such as sea surface temperature (SST), chlorophyll concentration, and temperature gradient (TGR) in the Southeast Pacific Ocean, this paper analyzed the resource variation of T. murphyi and its relationships with the spatiotemporal and environmental factors in the Ocean by using generalized additive model (GAM). The results showed that the rate of deviance explained about CPUE (catch per unit effort) was 31.47%. The fishing production of T. murphyi had distinct seasonal variation, and mainly concentrated in the 17th-41st weeks of the year, with the CPUE reached the highest in the 25th-31st weeks. The fishing ground of T. murphyi in the Ocean was mainly located in the waters of 78°-98° W and 30°-43.5° S. The suitable sea surface temperature was in the range of 12 ℃-18 ℃, and the optimum temperature was 14 ℃-16 ℃. The appropriate chlorophyll concentration range and temperature gradient were 0.09-0.18 mg·m-3 and 0.3 ℃-1.9 ℃, respectively. The results of stepwise GAM showed that the relative importance of the seven variables affecting the CPUE of T. murphyi was in the order of: weeks of the year, year, sea surface temperature, longitude, latitude, chlorophyll concentration, and temperature gradient.
    Research progress on forest fire whirl.
    2010, 21(04):  1056-1062. 
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    Fire whirl is a special fire behaviour that occurs in forest fire, and closely linked with crown fire and spot fire. Its generation mechanisms lie in the generation and development of rotating vortex. Establishing fire whirl simulation devices is one of the common research methods. In laboratory simulation tests, infrared thermography and thermocouple are adopted to measure flame temperature, while high-speed photography, three-dimensional laser Doppler, and Pitot tubes are used to measure fire whirl rotating speed. On the basis of experimental data, three-dimensional fire whirl models can be constructed.
    Transport of antibiotic resistance genes in environment and detection methods of antibiotic resistance.
    2010, 21(04):  1063-1069. 
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    The large scale use of antibiotics in medicine, animal husbandry, and aquaculture induces the increasing emergence of antibiotic resistance bacteria and antibiotic resistance genes (ARGs), and, as a kind of new environmental contaminants, the ARGs are attracted much attention by the public. This paper summarized the research progress of ARGs in recent years, and discussed the transport of ARGs in water, soil, and air, and in plants and animals. The necessity of the study on ARGs in environment and the existing problems in present studies were pointed out, and the research methods of antibiotic resistance (including antibiotic resistance bacteria and ARGs) were introduced. Some related research directions were proposed.
    Management modes of degraded ecosystem in southwest Karst area of China.
    2010, 21(04):  1070-1080. 
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    Ecologically fragile Karst area is a hotspot area concerned by academia. Owing to its intrinsic vulnerability and intense human activities, the ecosystem
     in this area is in degradation. Based on the degradation mechanisms of the ecosystem and the fragile degree of eco－environment in southwest Karst area of China, previous management experiences, and the factors leading to ecological deterioration, three types management modes of degraded ecosystem in ecologically fragile Karst area were summarized, i.e., ecological emigration-forest reservation-natural vegetation recovery, returning farmland into forestland-soil and water conservation-afforestation, and sustainable eco－agriculture-courtyard economy-resources industry. The appropriate areas for these modes, the problems needed to be paid attention in practices, and the cost－benefit analysis of these modes were also discussed.