Table of Content

18 August 2011, Volume 22 Issue 08

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Articles

Effects of elevated CO₂ concentration and nitrogen deposition on the biomass accumulation and allocation in south subtropical main native tree species and their mixed communities.

2011, 22(08):  1949-1954. 

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A 5-year experiment was conducted to study the effects of simulated elevated CO₂ concentration, nitrogen deposition, and their combination on the biomass accumulation and allocation in five south subtropical native tree species Schima superba, Ormosia pinnata, Acmena acuminatissima, Syzygium hancei, and Castanopsis hystrix and their mixed communities. The test tree species had different responses in their biomass accumulation and allocation to the elevated CO₂ concentration and nitrogen deposition. Elevated CO₂ concentration and nitrogen deposition increased the biomass of legume species by 49.3% and 71.0%, respectively, and promoted the biomass accumulation in sun species. Nitrogen deposition increased the biomass of shade-preference species significantly, but elevated CO₂ concentration was in adverse. Elevated CO₂ concentration inhibited the biomass allocation in the belowground part of sun species but promoted the biomass allocation in the belowground part of shade-preference species. Elevated CO₂ concentration, nitrogen deposition, and their interaction all promoted the biomass accumulation in mixed communities. Elevated CO₂ concentration increased the biomass accumulation in the belowground part of the communities, while nitrogen deposition increased the biomass accumulation in the aboveground part. Under the background of global climate change, Ormosia pinnata and Castanopsis hystrix tended to be the appropriate species for carbon fixation in south subtropical area.

Effects of aboveground and belowground competition between grass and tree on elm seedlings growth in Horqin Sandy Land.

2011, 22(08):  1955-1960. 

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Elm sparse woodland steppe plays an important role in vegetation restoration and landscape protection in Horqin Sandy Land. In this paper, a two-factor and two-level field experiment was conducted to explore the effects of aboveground and belowground competition between grass and tree on the growth of e
lm seedlings in the Sandy Land. Five aspects were considered, i.e., seedling biomass, belowground biomass/aboveground biomass, stem height, ratio of root to stem, and leaf number. For the one-year-old elm seedlings, their biomass showed a trend of no competition > aboveground competition > full competition > belowground competition, belowground biomass / aboveground biomass showed a trend of belowground competition > full competition > no competition > aboveground competition, stem height showed a trend of aboveground competition > no competition > full competition > belowground competition, root / stem ratio showed a trend of belowground competition > full competition > no competition > aboveground competition, and leaf number showed a trend of aboveground competition > no competition > belowground competition > full competition. Belowground competition had significant effects on the growth of one-year-old elm seedlings, while aboveground competition did not have. Neither belowground competition nor aboveground competition had significant effects on the growth of two-year-old elm seedlings. It was suggested that in Horqin Sandy Land, grass affected the growth of elm seedlings mainly via belowground competition, but the belowground competition didn’t affect the resource allocation of elm seedlings. With the age increase of elm seedlings, the effects of grass competition on the growth of elm seedlings became weaker.

Spatial heterogeneity of plant community species diversity in Ejina Oasis at the lower reaches of Heihe River.

2011, 22(08):  1961-1966. 

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By the method of geostatistics, this paper studied the spatial heterogeneity of plant community species diversity in Ejina Oasis at the lower reaches of Heihe River. In the study area, the Margalef richness index (M_a), Simpson diversity index (D_s), Shannon diversity index (H′) and Pielou evenness index (J′) were in normal distribution, and the coefficient of variation (CV) ranged from 55.8% to 67.8%, suggesting a moderate variability. The M_a and H′ were accorded with exponential models, and the D_s and J′ were accorded with spherical models. The H′ had the highest extent of spatial variation, followed by M_a, J′ and  D_s. Within the variable range, the structural factors in the spatial variation of M_a, D_s, H′, and J′ were dominant, ranging from 81.1% to 93.0%. The indices changed obviously parallel to the river, with significantly high values near Dalaihubu Town (42° N, 101° E), and obviously low values within the strips 100°-101° E and 102°-102°30′ E, mainly including east and west Gobi and the hinterland of Badain Jaran Desert.

Effects of simulated acid rain on  water physiological characteristics of Myrica rubra seedlings.

2011, 22(08):  1967-1974. 

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Taking the seedlings of typical subtropical economic tree species Myrica rubra in Zhejiang Province as test materials, a pot experiment was conducted to study their water physiological characteristics under effects of simulated acid rain (pH 2.5 and pH 4.0), with water (pH 5.6) as the control. Season, year, and acid rain all had significant effects on the  photosynthetic rate (P_n). Among the treatments, the P_n had a greater difference in summer than in spring and autumn, and was higher in treatment acid rain (pH 4.0). Season, year, acid rain, and the interactions of season and year and of the three factors had significant effects on the stomata conductance (G_s), and also, the G_s had a greater difference among the treatments in summer than in spring and autumn. Acid rain had inhibitory effect on G_s. Season, year, acid rain, and the interactions of season and year and of season and acid rain affected the transpiration rate (T_r) significantly. Same as P_n and G_s, the T_r had a greater difference among the treatments in summer than in spring and autumn. Acid rain (pH 2.5) had the strongest inhibitory effect on T_r. Acid rain and the interactions of season and year and of season and acid rain had significant effects on the water use efficiency (WUE), and acid rain (pH 2.5) had definitely positive effect on the WUE.

Characteristics of stemflow for typical alpine shrubs in Qilian Mountain.

2011, 22(08):  1975-1981. 

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Taking the typical alpine shrubs Potentilla fruticosa, Salix cupularis, Hippophae rhamnoides, and Caragana jubata in Qilian Mountain as test objects, a field investigation from June 1 to October 31, 2010 was conducted on the variation characteristics of the shrub stemflow, and analyzed the affecting effects of rainfall intensity and canopy structure morphology. The stemflow generated when the rainfall in early period was 2.1 mm, with an average of 3.4%, 3.2%, 8.0%, and 4.2% of the gross rainfall for P. fruticosa, S. cupularis, H. rhamnoides, and C. jubata, respectively. There was a significant positive linear correlation between the stemflow and rainfall intensity. With increasing rainfall, the stemflow percentage showed a trend of increase-decrease-increase. Stemflow played an important role in supplying water to the shrub rhizosphere, and the average funneling ratio was 59, 30, 110, and 49 for P. fruticosa, S. cupularis, H. rhamnoides, and C. jubata, respectively. The stemflow percentage had a significant exponential relationship with the maximum rain intensity in 10 minutes (I₁₀). When the I₁₀ was more than 6.0 mm·h^-1, the stemflow of H. rhamnoides and C. jubata showed a persistently increasing trend, while that of P. fruticosa and S. cupularis tended to be stable. Canopy structure morphology had complicated effects on the stemflow. In the same rainfall intensities, the height and crown projection area of the shrubs were the important factors affecting the generation of stemflow.

Age structures of Spodiopogon sibiricus populations on weedy meadow and elm woodland in Songnen Plain, Northeast China.

2011, 22(08):  1982-1986. 

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In 2003 and 2006, investigations were made on the age structures of Spodiopogon sibiricus populations as well as the matter productivities and vegetative reproduction capacities of different age-class modules of the populations on the weedy meadow and elm woodland in Songnen Plain of Northeast China. At the two habitats, the tillers of S. sibiricus all consisted of 2-3 age classes, and the rhizomes all composed of 4 age classes. Both the tillers and the rhizomes had the greatest proportion of 1- or 2-year-old, and the age structures were of expansive or stable. The 1- or 2-year-old  tiller-node buds were dominant, and the rhizome topmost buds occupied 29.4%-45.0%, being of significance to the population regeneration in the next year. The 1- or 2-year-old  modules of the tillers and rhizomes had the highest matter productivity and vegetative reproduction capacity, and the rhizomes had higher vegetative reproduction capacity than the tiller-nodes.

Effects of exogenous lead on the growth and lead accumulation characteristics of roadside dominant herbaceous plants in Shanxi Province.

2011, 22(08):  1987-1992. 

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A greenhouse pot experiment was conducted to study the effects of different concentration (0, 500, 1000, 1500 mg·kg^-1) lead (Pb) on the growth and Pb absorption and accumulation of 14 roadside dominant herbaceous plants in Shanxi Province. With increasing Pb concentration in the pot, Amaranthus retroflexus and Sorghum bicolor×S.sudanese appeared obviously toxic symptoms, while the other 12 test plants had higher Pb tolerance, with no significant decrease in their plant height and biomass, compared with control. Chenopodium album and Psathyrostachys juncea had the lowest Pb content (averaged 12.70 and 11.33 mg Pb·kg^-1, respectively) in their aboveground part and the lowest Pb ratio (0.12 and 0.10, respectively) of aboveground part / root, being the potential low Pb-accumulation plants and able to be used for the vegetation restoration of Pb-polluted soil. Red leaf A. tricolor and green leaf A. tricolor in treatment 1500 mg Pb ·kg^-1 had the highest Pb accumulation (53.37 and 45.29 mg Pb per 100 plants, respectively) in their aboveground parts, being able to be chosen as the pioneer plants for the remediation of Pb-polluted soil.

Impacts of salt stress on the growth and physiological characteristics of Rosa rugosa.

2011, 22(08):  1993-1998. 

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Taking 1-year old cuttings of a wild type and three cultivars of Rosa rugosa as test materials, this paper studied their biomass, photosynthesis, osmotic adjustment substance contents, root activity, and ion contents under the stress of different concentration NaCl. Salt stress inhibited the growth of the cuttings, and root was more sensitive than shoot. Under salt stress, wild rose had significantly higher contents of free proline and soluble sugar than the cultivars,and the contents of free proline and soluble sugar in cultivar ‘Ziyan’ were higher than those in cultivars ‘Zhongke 2’ and ‘Purple Branch’. Compared with rose cultivars, the wild rose under salt stress had smaller changes in its photosynthetic characteristics and root activity. It was suggested that wild rose had a higher resistance to salt stress than the cultivars, and cultivar ‘Ziyan’ had a higher resistance than ‘Purple Branch’ and ‘Zhongke 2’. All the test indices could be used as the indicators of R. rugosa salt-tolerance.

Soil nutrient status of pure birch and larch plantations based on their seedlings bioassay.

2011, 22(08):  1999-2004. 

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One-year-old birch (Betula platyphylla) and larch (Larix olgensis) seedlings were respectively planted in pots with the soils taken from 35-year-old  pure birch and larch plantations, and the seedlings growth, biomass increment, foliar nutrient content, and soil nutrient status were monitored, aimed to evaluate the fertility levels of the two soils and the possible interspecific interaction in mixed larch-birch forest. Birch soil had significantly higher contents of total N and available N than larch soil, while larch soil had significantly higher contents of total P, available P, and total K than birch soil (P<0.05). In the first growth season, the height and collar diameter growth and the biomass accumulation of birch seedlings growing on birch soil were 69%, 52%, and 65% (P<0.05) higher than those growing on larch soil, and the larch seedlings also had 12%, 8%, and 37% gains of the indices, respectively. The foliar N concentration of both larch and birch seedlings growing on birch soil was higher than that on larch soil, while the foliar P concentration was higher when the seedlings were growing on larch soil than on birch soil. The birch soil had higher content of available N because of the higher litterfall, while the larch soil had greater available P because of the higher P mobilizing effect. It was predicted that in mixed birch-larch forest, the complementary interaction of soil N and P could benefit the growth of the two tree species.

Effects of simulated nitrogen deposition on soil available nitrogen forms and their contents in typical temperate forest stands.

2011, 22(08):  2005-2012. 

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An indoor experiment was conducted to study the effects of simulated nitrogen deposition on the soil available N in typical temperate forest stands. During the  experiment period, nitrogen deposition increased the soil NH₄⁺-N, NO₃^--N, and available N contents, as compared with the control, but the increments differed with stand types, soil layers, nitrogen treatment types, and treatment duration. Mixed forest soil had weaker responses in its available N contents to the nitrogen deposition than broad-leaved forest soil but stronger responses than artificially pure coniferous forest soil, and soil A horizon was more sensitive to nitrogen deposition than soil B horizon. Ammonium nitrogen deposition had larger effects on soil NH₄⁺-N content, nitrate nitrogen deposition had larger effects on soil NO₃^--N content, while mixed ammonium and nitrate nitrogen deposition increased the contents of both soil NH₄⁺-N and soil NO₃^--N, and the increments were higher than those of ammonium nitrogen deposition and nitrate nitrogen deposition, suggesting the additive effects of the mixed ammonium and nitrate nitrogen deposition on the forest soil available N.

Carbon storage, density, and distribution in forest ecosystems in Jilin Province of Northeast China.

2011, 22(08):  2013-2020. 

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By using forest resources inventory data and field investigation data, this paper studied the carbon storage, density, and distribution characteristics in forest ecosystems in Jilin Province of Northeast China. The total carbon storage in the forest ecosystems was 1827.293 Tg C, and the carbon storages in arbor layer, shrub-grass layer, litter layer, and soil were 439.152 Tg C, 5.195 Tg C, 45.600 Tg C, and 1330.466 Tg C, accounting for 24.1%, 0.3%, 2.5%, and 73.1% of the total, respectively. The carbon density in the forest ecosystems was 225.304 Mg C·hm^-2, with 54.352 Mg C·hm^-2 in arbor layer, 0.643 Mg C·hm^-2 in shrub-grass layer, 5.644 Mg C·hm^-2 in litter layer, and 164.666 Mg C·hm^-2 in soil. Different types of the forest ecosystems had a carbon storage varied from 9.357 Tg C to 959.716 Tg C and a carbon density ranged from 180.648 Mg C·hm^-2 to 254.627 Mg C·hm^-2, with the highest values in soil and the lowest values in shrub-grass layer. Overall, the carbon storage and density in the forest ecosystems were greater in eastern mountainous area than in central and western plains. In the Province, middle-aged forests had a greater proportion than the forests in other age classes, and thereby, a proper management of the present forests could increase the carbon sequestration of the forest ecosystems.

Changes of China agricultural climate resources under the background of climate change. Ⅷ. Change characteristics of heat resources during the growth period of double cropping rice in Jiangxi Province.

2011, 22(08):  2021-2030. 

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Based on the observation data from the meteorological stations and agricultural experimental stations in Jiangxi Province, this paper studied the change trend of the growth period of double cropping rice in the province, and, by using the indices growing degree-days (GDD), cool degree-days (CDD), and heat degree-days (HDD), the change trends of the heat resources at each growth stage of the double cropping rice in 1981-2007 were analyzed. Under the background of climate warming, the mean air temperature, mean minimum air temperature, mean maximum air temperature during the growth period of the double cropping rice all had an increasing trend, leading to the shortening of double cropping rice growth season, with the most obvious decrease of vegetative growth phase and the prolonged reproductive growth phase. In the vegetative growth phase, the GDD and HDD increased, while the CDD decreased. In 1981-2007, the effective heat resources of double cropping rice in Jiangxi Province increased, low temperature risk reduced, while high temperature risk increased. The increment of the effective heat resources for double cropping rice was higher in northeast Jiangxi than in southwest Jiangxi, low temperature risk was higher in south Jiangxi than that in north Jiangxi, and high temperature risk was the highest in middle Jiangxi.

Effects of applying controlled-release fertilizer and its combination with urea on nitrous oxide emission during rice growth period.

2011, 22(08):  2031-2037. 

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By the method of static chamber, a field experiment was conducted to study the effects of applying controlled-release fertilizer (CRF) and its combination with urea on the N₂O emission during rice growth period. Four treatments, i.e., no fertilization (CK), urea (U), urea and CRF with a ratio of 3：7 (U+C), and CRF(C) were installed, and the N application rate in treatments U, U+C, and C was the same. Compared with treatment U, treatments U+C and C decreased theN₂O emission during rice growth season by 40.4% and 59.6%, and decreased the emission at midseason aeration stage by 65.1% and 83.9%, respectively (P<0.05). Compared with that in treatment C, the N₂O emission in treatment U+C had a slight decrease, and decreased by 53.9% at midseason aeration stage. Applying CRF increased rice yield, and the increment in treatments C and U+C was 7.8% and 9.8%, respectively, as compared to treatment U. Applying CRF delayed the peak time of soil inorganic nitrogen concentration, resulting in the reduction of N₂O emission at midseason aeration stage. During rice growth season, no significant correlation was observed between N₂O flux and soil Eh or soil temperature.

Effects of nitrogen application and ridge film furrow planting on water use of winter wheat in dry land of South Shanxi.

2011, 22(08):  2038-2044. 

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A 2-year (2008-2010) field experiment was conducted to study the effects of basal dressing nitrogen, topdressing nitrogen, and ridge film furrow planting on the 0-2 m soil moisture status and the grain yield and water use efficiency of winter wheat in rain-fed area of South Shanxi Province. In all treatments, the soil moisture status during winter wheat growth period had the same change trend, being increased steadily from pre-sowing to revival stage and decreased sharply from revival stage to heading stage, and then increased gradually till maturity stage. From revival stage to heading stage, the soil water consumption was the most. Increasing nitrogen basal application rate or topdressing nitrogen increased the soil water consumption, widened the soil moisture active layer, and deepened the relatively stable layer. Topdressing nitrogen increased grain yield significantly; ridge film furrow planting decreased soil water consumption obviously. The water use efficiency under ridge film furrow planting was 23.4% and 39.1% higher than that under conventional planting system in 2009 and 2010 (P<0.01). The grain yield under ridge film furrow planting plus topdressing nitrogen was 3643 kg·hm^-2, which was significantly higher than that under single ridge film furrow planting or topdressing nitrogen, displaying a preferable water-fertilizer coupling effect.

Salt tolerance evaluation of cotton (Gossypium hirsutum) at its germinating and seedling stages and selection of related indices.

2011, 22(08):  2045-2053. 

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A sand culture experiment was conducted to study the salt tolerance of 13 cotton cultivars at their germinating and seedling stages under the stress of different concentration NaCl, and a cluster analysis was made on the salt tolerance, according to the subjection values of salt toxicity coefficients of multi-indices and the sum subjection value. It was observed that the appropriate concentration of NaCl for the evaluation of salt tolerance was 150 mmol·L^-1. The salt tolerance differed with cultivar and growth stage. Among the 13 cultivars, the CCRI-44 and CCRI-177 were steadily salt-tolerant at both germinating and seedling stages, the CCRI-103, Dexiamian 1, and NuCOTN 33B were steadily and moderately salt-tolerant, while the CCRI-102, Sumian 12, and Simian 3 were steadily salt-sensitive. Germination rate, germination potential, germination index, vigor index, and fresh mass could be served as the indicators to evaluate the salt tolerance of the cultivars at germinating stage, while plant height, leaf expansion rate, shoot dry mass, root dry mass, root vigor, and net photosynthetic rate could be applied to assess the salt tolerance at seedling stage.

Effects of solar greenhouse vegetable cultivation on soil physical quality.

2011, 22(08):  2054-2060. 

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Taking the solar greenhouse heavy loam soil having been planted vegetables for different years at Yunyang Town in Jingyang County of Shaanxi Province as test objects, and with the uncovered vegetable soil adjacent to the greenhouse as the control, this paper studied the effects of solar greenhouse vegetable cultivation on soil physical quality. Solar greenhouse vegetable cultivation had greater effects on the bulk density of 0-30 cm soil layer (an increase in 0-10 cm soil layer and a decrease in 10-30 cm soil layer), but little effects on that of 30-40 cm soil layer. In 0-40 cm solar greenhouse soil profile, the contents of <0.01 mm physical clay and <0.001 mm clay were lower in upper layer than in deeper layer, indicating their downward movement, and this phenomenon was more obvious with increasing year of solar greenhouse vegetable cultivation. Within the first 5 years of solar greenhouse vegetable cultivation, soil field water capacity decreased significantly, with a decrement of 13.8%, but remained relatively stable after then.

Effects of sunken depth of energy-saving solar greenhouse on the diurnal variation and spatial distribution of environmental factors in the greenhouse.

2011, 22(08):  2061-2068. 

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Taking the energy-saving solar greenhouses with the same infrastructure but different sunken depths (0, 0.5, 1.0, and 1.5 m) in Tai’an of Shandong Province as test objects, this paper analyzed the intercepted amount of direct solar radiation energy, and studied the diurnal variation and spatial distribution patterns of environmental factors in the greenhouses on winter solstice (December 20-24, 2009) and summer solstice (June 19-23, 2010). With the increase of sunken depth, the shadow areas in the greenhouses caused by sunken profiles increased gradually, the direct solar radiation energy into the interior of the greenhouses shifted from south to north, and the ratio of ground radiation to back wall radiation decreased gradually. Within the range of 0-1.0 m sunken depth, the air temperature and soil temperature in the greenhouses increased significantly with increasing sunken depth; but when the sunken depth was 1.5 m, the warming effect declined significantly, and the deviation of the lowest soil temperature increased. The deeper the sunken depth, the lower the light intensity and the higher the relative humidity in the greenhouses were. In considering of both lighting and heat preservation, the appropriate sunken depth of energy-saving sunlight greenhouses with a span of 10 m in Tai’an region should be less than 1.0 m.

Dynamic changes of surface soil organic carbon and light-fraction organic carbon after mobile dune afforestation with Mongolian pine in Horqin Sandy Land.

2011, 22(08):  2069-2074. 

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This paper studied the dynamic changes of surface (0-15 cm) soil organic carbon (SOC) and light-fraction organic carbon (LFOC) in 25- and 35-year-old sand-fixing Mongolian pine (Pinus sylvestris var. mongolica) plantations in Horqin Sandy Land, with a mobile dune as a comparison site. After the afforestation on mobile dune, the content of coarse sand in soil decreased, while that of fine sand and clay-silt increased significantly. The SOC and LFOC contents also increased significantly, but tended to decrease with increasing soil depth. Afforestation increased the storages of SOC and LFOC in surface soil, and the increment increased with plantation age. In the two plantations, the increment of surface soil LFOC storage was much higher than that of SOC storage, suggesting that mobile dune afforestation had a larger effect on surface soil LFOC than on SOC.

Crop-soil nitrogen cycling and soil organic carbon balance in black soil zone of Jilin Province based on DSSAT model.

2011, 22(08):  2075-2083. 

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By using the CERES-Maize crop model and Century soil model in Decision Support System of Agrotechnology Transfer (DSSAT) model, this paper studied the effects of crop management parameters, fertilizer N application rate, soil initial N supply, and crop residue application on the maize growth, crop-soil N cycling, and soil organic C and N ecological balance in black soil (Mollisol) zone of Jilin Province, Northeast China. Taking 12000-15000 kg·hm^-2 as the target yield of maize, the optimum N application rate was 200-240 kg N·hm^-2. Under this fertilization, the aboveground part N uptake was 250-290 kg N·hm^-2, among which, 120-140 kg N·hm^-2 came from soil, and 130-150 kg N·hm^-2 came from fertilizer. Increasing the N application rate (250-420 kg N·hm^-2)induced an obvious increase of soil residual N (63-183 kg·hm^-2); delaying the N topdressing date also induced the increase of the residual N. When the crop residue application exceeded 6000 kg·hm^-2, the soil active organic C and N could maintain the supply/demand balance during maize growth season. To achieve the target maize yield and maintain the ecological balance of soil organic C and N in black soil zone of Jilin Province, the chemical N application rate would be controlled in the range of 200-240 kg N·hm^-2, topdressing N should be at proper date, and the application amount of crop residue would be up to 6000 kg·hm^-2.

Vulnerability assessment of eco-environment in Yimeng mountainous area of Shandong Province based on SRP conceptual model.

2011, 22(08):  2084-2090. 

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Based on the ecological sensitivity-resilience-pressure (SRP) conceptual model, and selecting 13 indices including landscape diversity index, soil erosion, and elevation, etc., the vulnerability of the eco-environment in Yimeng mountainous area of Shandong Province was assessed under the support of GIS and by using principal component analysis and hierarchy analytical method. According to the eco-environmental vulnerability index (EVI) values, the eco-environment vulnerability of study area was classified into 5 levels, i.e., slight (<1.8), light (1.8-2.8), moderate (2.8-3.5), heavy (3.5-4.0), and extreme vulnerability (>4.0). In the study area, moderately vulnerable area occupied 43.3% of the total, while the slightly, lightly, heavily, and extremely vulnerable areas occupied 6.1%, 33.8%, 15.9%, and 0.9%, respectively. The heavily and extremely vulnerable areas mainly located in the topographically complicated hilly area or the hill-plain ecotone with frequent human activities.

Spatiotemporal dynamics of land cover in northern Tibetan Plateau with responses to climate change.

2011, 22(08):  2091-2097. 

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By using the 2001-2008 MODIS land cover products (MCD12Q1) and based on the modified classification scheme embodied the characteristics of land cover in northern Tibetan Plateau, the annual land cover type maps of the Plateau were drawn, with the dynamic changes of each land cover type analyzed by classification statistics, dynamic transfer matrix, and landscape pattern indices. In 2001-2008, due to the acceleration of global climate warming, the areas of glacier and snow-covered land in the Plateau decreased rapidly, and the melted snow water gathered into low-lying valley or basin, making the lake level raised and the lake area enlarged. Some permanent wetlands were formed because of partially submersed grassland. The vegetation cover did not show any evident meliorated or degraded trend. From 2001 to 2004, as the climate became warmer and wetter, the spatial distribution of desert began to shrink, and the proportions of sparse grassland and grassland increased. From 2006 to 2007, due to the warmer and drier climate, the desert bare land increased, and the sparse grassland decreased. From 2001 to 2008, both the landscape fragmentation degree and the land cover heterogeneity decreased, and the differences in the proportions of all land cover types somewhat enlarged.

Simulation of vegetation landscape in Pingtan Island based on BP neural network model.

2011, 22(08):  2098-2104. 

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Taking GIS as technical platform and by using Matlab 7.0, the vegetation landscape in Pingtan Island was cut with 2 km×2 km grid graph. The data of 50 quadrats were obtained. Forty-four of the 50 quadrates were used for model training, and the rest 6 were used for model checking. Fractal dimension, Shannon diversity index, and contagion index were selected as output data of the model, and the number of residential quarter, wind speed, and the distance from the coast were chosen as affecting factors. A BP neural network model of vegetation landscape in Pingtan Island was established, and was checked by error test. The results demonstrated that the major factors affecting the vegetation landscape spatial pattern and diversity in Pingtan Island were wind speed and the distance from the coast, and anthropogenic factors had greater effects on the spatial connection of vegetation landscape. The fitted results of the relationships between vegetation landscape and environmental and anthropogenic factors were basically accorded with the truth. The average error was 7.4%, and the minimum error was 0.2%, indicating that the model could be applied to quantitatively predict and simulate the vegetation landscape in Pingtan Island.

Priority areas for biodiversity conservation in Hainan Island: Evaluation and systematic conservation planning.

2011, 22(08):  2105-2112. 

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A total of 140 endangered species in Hainan Island were selected as indicator species, and their spatial distribution patterns were analyzed by using mechanism habitat model. Based on the iterative operation with systematic conservation planning tool MARXAN, the priority areas of these species were identified and evaluated. The priority areas had an area of 5383.7 km², accounting for 15.6% of the total land area of the Island, and mainly distributed in some forest regions (Yinggeling, Jianfengling and Wuzhishan) and in northern part water source regions. In the priority areas, the conservation proportion of 11 1st grade indicator species habitats occupied at least 65% of all the habitats. Through the gap analysis of priority areas and current nature reserves, it was suggested that an expansion of Jianfengling, Yinggeling-Limushan, and Wuzhishan-Diaoluoshan nature reserves and the establishment of Baolonglinchang-Linbiling-Fuwanling protection system should be made, and the protection areas for water source conservation and endangered species should be established in the northern part of the Island.

Applications of habitat equivalency analysis in ecological damage assessment of oil spill incident.

2011, 22(08):  2113-2118. 

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Habitat equivalency analysis (HEA) is one of the methods commonly used by U.S. National Oceanic and Atmospheric Administration in natural resources da
mage assessment, but rarely applied in China. Based on the theory of HEA and the assessment practices of domestic oil spill incidents, a modification on the HEA was made in this paper, and applied to calculate the habitat value in oil spill incidents. According to the data collected from an oil spill incident in China, the modified HEA was applied in a case study to scale the compensatory-restoration. By introducing the ecological service equivalent factor to transfer various habitats, it was achieved to value of the injured habitats in ecological damage assessment of oil spill incident.

Characteristics of non-point source pollution in Tiaoxi watershed and related affecting factors.

2011, 22(08):  2119-2125. 

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By using soil and water assessment tool (SWAT) model, this paper simulated the surface runoff intensity and the export loadings of sediment particulates and nutrients via non-point source hydrological pathway in Tiaoxi watershed, and integrated with the simulation results, analyzed the temporal and spatial distribution characteristics of non-point source pollution in the watershed in 2008. In the study area, the per unit area non-point source pollution was stronger
 in northern region than in southern region and in eastern region than in western region, and the weakest in central region. Among the land utilization types, farmland had the biggest contribution to the sediment loading. There were significantly positive correlations between the loadings of surface runoff and associated sediment particulates and the rainfall intensity. The export loadings of nutrients through surface runoff were higher in rainy season (from June to September) than in dry season (from December to next March), and there existed significant correlations between the surface runoff loadings of sediment particulates, organic nitrogen, and nitrate and the average gradient of lands.

Spatial pattern and its variation of Cnaphalocrocis medinalis larvae and Ummeliata insecticeps under paddy rice cropping neighboring with vegetables or corn.

2011, 22(08):  2126-2132. 

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Geostatistical methods were adopted to characterize the spatial pattern and its variation of Cnaphalocrocis medinalis larvae (Lepidoptera: Crambidae) and Ummeliata insecticeps (Araneida: Linyphiidae) in the habitats of paddy rice neighboring with white melon, tomato, or corn. In the rice growth period, C. medinalis larvae and U. insecticeps presented aggregative distribution, with the spatial range varied from 1.91 to 182.57 m and from 3.70 to 9.70 m, respectively. Isoline map showed that the density of U. insecticeps was spatially and temporally identical with that of C. medinalis larvae, suggesting that U. insecticeps had strong pursuing and control effects on C. medinalis larvae. Among the test neighboring patterns, paddy rice neighboring with white melon had the best performance of U. insecticeps.

Effects of Bt corn straw insecticidal proteins on enzyme activities of Eisenia fetida.

2011, 22(08):  2133-2139. 

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Bacillus thuringiensis (Bt ) proteins released from Bt corn can enter soil ecosystem via returning straw into field, root exudation, and pollen fluttering-down. In this study, the straws of Bt corn and its near-isogenic non-Bt line were added into soil with an application rate of 5% and 7.5% to breed Eisenia fetida, and the total protein content and the activities of acetylcholine esterase (AchE), glutathione peroxidase (GSH-PX), catalase (CAT), and superoxide dismutase (SOD)  in E. fetida were determined after 7 and 14 days. Under the same application rate of the straws, the total protein content and GSH-PX activity of E. fetida decreased while the AchE, CAT, and SOD activities increased on the 14th day, compared with those on the 7th day. The Bt corn straw increased the SOD activity and decreased the AchE and GSH-PX activities, but had less effects on the total protein content and CAT activity, compared with non-Bt corn straw. All the results suggested that Bt corn straw had no inhibitory effect on E. fetida total protein but could inhibit the AchE and GSH-PX activities, and could not induce CAT activity but induce SOD activity within a short time.

Colonization and disease control and fruit preservation functions of endophytic bacterial strains in lychee.

2011, 22(08):  2140-2146. 

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By spraying the GFP-marked endophytic bacterial strains BS-2-gfp and TB2-gfp, this paper studied their colonization in lychee organs and the functions of the strains in disease control and fruit preservation. The BS-2-gfp and TB2-gfp could colonize and propagate in lychee leaves, flowers, un-matured fruits, and matured fruits, and transfer from the flowers to un-matured fruits. The colonization of BS-2-gfp and TB2-gfp in lychee leaves varied with season and growth stage, being larger in quantity and longer in duration in spring than in autumn. The colonization quantity and duration of the strains also differed in other organs. Both the BS-2-gfp and the TB2-gfp could be isolated and recovered from lychee leaves after 37 d inoculation, the BS-2-gfp could not be isolated from the flowers after inoculation for 10 d, and the BS-2-gfp and TB2-gfp had the largest colonization quantity in matured fruits. The colonization quantity of TB2-gfp in lychee pericarp reached to the maximum (1.90×10⁶ CFU·g^-1FM) when the disease index of litchi downy blight had a sharp increase, and, compared with BS-2-gfp, the TB2-gfp had better fruit preservation efficiency, and its colonization quantity in lychee pericarp was also higher. It was suggested that there was a positive correlation between the colonization quantity of test bacterial strains in lychee pericarp and the disease control and fruit preservation effect.

Resistance Realized heritability and risk assessment of Panonychus citri to avermectin and fenpropathrin. 

2011, 22(08):  2147-2152. 

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On the basis of resistance breeding and selection in laboratory, and by using the threshold trait analysis in quantitative genetics, this paper studied the realized resistance heritability of Panonychus citri (McGregor) collected from Beibei of Chongqing to avermectin and fenpropathrin, and predicted the resistance risk of P. citri to these two acaricides. After 11- and 16-generations of selection with avermectin and fenpropathrin, the resistance of P. citri to the two acaricides increased by 3.8- and 29.9-fold, and the realized resistance heritability was 0.0475 and 0.1544, respectively. Under laboratory condition, to develop a 10-fold increase of resistance required 12-26 generations of selection for avermectin, and 7-16 generations of selection for fenpropathrin under the selection pressure of 50%-90% mortality for each generation. Under field condition, it would require more generations to develop the same resistance level. Comparing with bioacaricide avermectin, pyrethroid fenpropathrin had obviously higher resistance risk to P. citri. The results provided references for the resistance management of P. citri to acaricides.

Responses of ground arthropod functional groups to the enclosure of grazing grassland in desert steppe.

2011, 22(08):  2153-2159. 

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With the support of the National Resources Monitoring Station in Yanchi County of Ningxia, an investigation was conducted on the ground arthropods, vegetations, and soil properties in the enclosed and un-enclosed grazing grassland in desert steppe. In the meantime, the functional groups of ground arthropods were classified according to their feeding habits. The ground arthropods in the desert steppe could be classified into four functional groups, i.e., predatory, phytophagous, saprophagous, and omnivorous, among which, predatory and phytophagous groups were dominant in quantity, and phytophagous and saprophagous groups were predominant in biomass, implying that the ground arthropod  in desert steppe was mainly characterized by phytophagous arthropods. Enclosure increased the individual and group number of predatory, phytophagous, and omnivorous arthropods as well as the biomass of predatory and omnivorous arthropods, and enhanced the biodiversity of predatory and phytophagous arthropods, which was closely correlated with the vegetation recovery and soil environment improvement, and demonstrated that the enclosure of grazing grassland increased the diversity and complexity of ground arthropod functional groups in desert steppe. Nevertheless, the individual number and biomass of saprophagous arthropods decreased after the enclosure, reflecting the dependence of these arthropods on grazing grassland.

Effects of artificial reef construction to marine ecosystem services value: A  case of Yangmeikeng artificial reef region in Shenzhen.

2011, 22(08):  2160-2166. 

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Based on the researches and statistic data of Yangmeikeng artificial reef region in Shenzhen in 2008 and by the method of ecosystem services value, this paper analyzed the effects of artificial reef construction in the region on the marine ecosystem services. After the artificial reef construction, the tourism service value in the region decreased from 87% to 42%, food supply service value increased from 7% to 27%, and the services value of raw material supply, climatic regulation, air quality regulation, water quality regulation, harmful organism and disease regulation, and knowledge expansion had a slight increase, as compared to the surrounding coastal areas. The total services value per unit area of Yangmeikeng artificial reef region in 2008 was 1714.7×10⁴ yuan·km^-2, far higher than the mean services value of coastal marine ecosystem in the surrounding areas of Shenzhen and in the world. Artificial reef construction affected and altered the structure of regional marine ecosystem services value, and improved the regional ecosystem services value, being of significance for the rational exploitation and utilization of marine resources and the successful recovery of damaged marine eco-environment and fish resources. Utilizing the method of ecosystem services value to evaluate artificial reef construction region could better elucidate the benefits of artificial reef construction,effectively promote the development of our artificial reef construction, and improve the management of marine ecosystem.

Sexual reproductive allocation of Sargassum thunbergii at Taiping Cape of Yellow Sea.

2011, 22(08):  2167-2172. 

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This paper studied the dynamics of reproductive allocation (RA) of Sargassum thunbergii during its sexual reproductive season and the related environmental  factors at the Taiping Cape of Yellow Sea. The sexual reproduction of  S. thunbergii initiated in early June, peaked in mid July when the sea
water temperature was about 22 ℃ (the mean proportion of biomass allocated to reproductive organs on July 19 was 76.7%), and ended in late August. The RA had a significant linear correlation with the average length of thallus branches (r=0.855,P<0.01). The thalli with a  length less than 10 cm showed a lower RA in the whole sexual reproductive season, while the thalli longer than 10 cm had a RA up to averagely 70.0% at the peak maturing stage. UNIANOVA analysis showed that both tidal level and wave strength had significant effects on the RA of S. thunbergii (tidal level: F=175.62, P<0.01; wave strength: F=95.35,P<0.01), and there was a significant interaction between tidal level and wave strength (F=9.14,P<0.05). The sizes of the effects were in the order of tidal level > wave strength > tidal level × wave strength.

Secondary productivity of macrobenthos in rocky intertidal zone of Yushan Islands, Zhejiang Province.

2011, 22(08):  2173-2178. 

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In order to understand the current status of macrobenthos in intertidal zone of Yushan Islands, macrobenthos samples were collected from 5 sections in the intertidal zone in four seasons from March 2009 to January 2010, with the density, biomass, secondary productivity, and P/B value of the macrobenthos investigated by using Brey’s empirical formula. The mean density of the marobenthos was 1419.5 ind·m^-2, mean biomass in ash free dry mass (AFDM) was 565.53 g·m^-2, mean annual secondary productivity was 285.58 g·m^-2·a^-1(AFDM), and mean annual P/B value was 0.51. The secondary productivity was mainly affected by mollusca and gastropda, with five critical species Septifer virgatus, Modiolus modiolus, Serpulorbis imbricata, Tetraclita japonica,and T. squamosa contributed 84.0 % of the total. The P/B value in the study area was lower than that in other sea areas, showing that the generation turnover rate of the macrobenthos in the intertidal zone of Yushan Islands was slower, and the community structure was more stable.

Impacts of ultraviolet irradiation on the sperm motility and longevity of Acipenser baerii.

2011, 22(08):  2179-2183. 

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This paper studied the impacts of different dose ultraviolet irradiation (254 nm, UVC) on the sperm motility and longevity of Acipenser baerii. Ultraviolet irradiation had significant impacts on the sperm motility, its fast motion
 time, and longevity. With the increasing dose of ultraviolet irradiation, the s
perm motility decreased rapidly first, increased rapidly then, and decreased rapidly again. The sperm fast motion time had the similar variation trend as the spe
rm motility, but the sperm longevity kept decreasing with increasing dose of ult
raviolet irradiation. When the ultraviolet irradiation dose increased to 288 mJ·
cm-2, the sperm fast motion disappeared; when the ultraviolet irradiation
dose increased up to 324 mJ·cm-2, the sperm had no motility and died. According to the “Hertwig effect”, the optimum ultraviolet irradiation dose for inactivating A. baerii sperm was 216 mJ·cm-2.

Edge effect and its impacts on forest ecosystem: A review.

2011, 22(08):  2184-2192. 

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Edge effect is an important concept in ecology and biological conservation, playing an important role in the study of ecological processes such as energy and material flow at ecosystem scale and landscape scale. This paper expatiated the connotation, features, quantitative evaluation (basis of quantitative analysis, strength, impact zone, and models, etc.), and applied aspects of edge effect, summarized the impacts of edge effect on forest ecosystem, analyzed the deficiencies in the study of edge effect, and prospected related research directions, aimed to provide references for forest and protected area management.

Effects of seasonal snow cover on soil nitrogen transformation in alpine ecosystem: A review.

2011, 22(08):  2193-2200. 

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Seasonal snow cover has pronounced effects on the soil nitrogen concentration and transformation in alpine ecosystem. Snowfall is an important form of nitrogen deposition, which directly affects the content of soil available nitrogen. Different depths and different duration of snow cover caused by snowfall may lead the heterogeneity of abiotic factors (soil temperature and moisture) and biotic factors (soil microbes, alpine plants, and alpine animals), and further, produce complicated effects on the mineralization and immobilization of soil nitrogen. This paper introduced in emphasis the inherent mechanisms of soil nitrogen mineralization and leaching under the effects of frequent freeze-thaw events during the durative melting of snow cover, and summarized the main research results of field in situ experiments about the effects of seasonal snow cover on soil nitrogen in alpine ecosystem based on the possible changes in snow cover in the future. Some suggestions with regard to the effects of seasonal snow cover on soil nitrogen were put forward.

Technical strategies in the research of plant salt-responsive proteomics: A review.

2011, 22(08):  2201-2210. 

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Soil salinization is one of the key factors limiting plant growth and distribution.To explore plant molecular salt-responsive mechanisms is the basis of enhancing plant salt tolerance in virtue of molecular biological techniques, and also, the hotspot of plant physiology and molecular ecology. High throughput proteomics approaches include two-dimensional electrophoresis (2-DE), blue-native/SDS-PAGE (BN/SDS-PAGE), two-dimensional fluorescence difference gel electrophoresis (2D DIGE), liquid chromatography (LC), and various mass spectrometry (MS) techniques, being widely applied in the research of plant salt-response and supplied important information for understanding plant molecular salt-tolerant mechanisms. In this paper, a review was made on the technical strategies applied in the research of plant salt-responsive proteomics.

Otolith microchemistry of tuna species: Research progress.

2011, 22(08):  2211-2218. 

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Microchemistry analysis of trace elements and isotopes in fishes’calcified substances is an emerging approach to analyze the population structure, life history, and migration environmental history of fishes. With the increasing improvement of the researches and applications of otolith microchemistry, this approach has been a good tool for studying the ecology of tuna species. Currently, the research contents of tuna species’otolith microchemistry mainly include trace elements and isotopes, and the former is the emphasis and hotspot in applied research, playing a vital role in the researches of population partitioning, natal origin, migration environmental history, and life history of tuna species, especially bluefin tuna. However, most of the researches are focusing on the variation of otolith’s Sr/Ca ratio, and there is no final conclusion on the relationships between the fractionation of isotopes C and O in otolith and the temperature. For the sake of exploiting the huge value of otolith microchemistry, it would be necessary to strengthen the researches on the deposition mechanisms of trace elements in otolith, and to analyze the spatio-temporal variations of various trace elements in otolith by comprehensive research methods.

Bio-treatment of grease wastewater: Research progress.

2011, 22(08):  2219-2226. 

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In conventional wastewater bio-treatment, little attention has been paid on the bio-degradation of grease, causing low efficiency in the process, and thereby, further study should be made on the development and application of related mature and effective bio-treatment techniques. This paper summarized the pathways and mechanisms of grease bio-degradation in wastewater treatment, with the focus on the research progress in the functional microbes involved in lipid hydrolysis and long-chain fatty acid degradation, and briefly introduced a series of new treatment technologies based on the habitat differences of the functional microbes. The key breakthrough directions in the technological study of grease bio-degradation were prospected, expecting to provide theoretical guidance to the development of the related technologies.