Table of Content

18 July 2011, Volume 22 Issue 07

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Articles

Regeneration characteristics and related affecting factors of Pinus tabulaeformis secondary forests in Qinling Mountains.

2011, 22(07):  1659-1667. 

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The study with sampling plot method showed that in Pinus tabulaeformis secondary forests in Qinling Mountains, there were 36 tree species in regeneration layer, occupying 51.4% of the total. The dominant species were Quercus glandulifera, Quercus aliena var. acuteserrata, and Corylus heterophylla. The seedling bank was abundant, and with lower height class and age class. The main regeneration type was seedling, showing the forest being at its middle succession period. Stand density had significant effects on sapling and seedling densities (P<0.01). The sapling and seedling densities increased when the stand density increased from 580 trees·hm^-2 up to 1500 trees·hm^-2, but decreased with the further increase of stand density. Slope aspect also had significant effects on the seedling and sapling densities (P<0.05). The sapling density decreased gradually when the slope aspect changed from SW10° to
SW40°, but increased with the slope aspect changed to shady slope (NE10°). The forest regeneration characteristics differed at different slope positions,with the sapling and seedling densities being relatively higher in flat stand. From foot to top, the seedling density decreased, while the sapling density increased. The sapling density increased from the altitude 1159 m up to 1449 m but decreased from 1449 m up to 1658 m, while the seedling density all along had an increasing trend from lower altitude to higher altitude. It was suggested that the medium stand density on shady slope had the best natural regeneration. To rationally regulate stand density could be an effective way to accelerate the regeneration process of P. tabulaeformis forest.

Community structure and distribution pattern of a natural secondary forest in Beigou forest farm.

2011, 22(07):  1668-1674. 

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Taking the 4 hm² fixed sampling plot in the Beigou forest farm of Weichang County in Hebei Province as test object, and by adopting the parameters (point pattern distribution, mingling, and size differentiation), this paper analyzed the community structure and distribution pattern of a natural secondary forest in the farm. There were eleven populations in the arbor layer of the forest, among which, Populus davidiana and Betula platyphylla had the obvious advantage in population density and basal area, being the dominant and constructive species of the arbor layer. Spatially, these two species all presented cluster modes remarkably, and competed each other greatly. The main accompanying species Larix principis-rupprechti and Acer truncatum also presented cluster modes, but the density and volume were significantly lower than the two dominant species’, not able to compete with the dominate species. Affected by the low mingling of dominant species, the average mingling of the whole stand was only 0.40, while the mingling of accompanying species generally presented moderate or high. The mean size differentiation of the whole stand was 0.49, and P. davidiana, B. platyphylla, L. principis-rupprechti, and Quercus mongolica were of dominance or sub-dominance in the spatial structural units, while the other accompanying species had no obvious dominance.

Forest soil organic carbon density and its distribution characteristics along an altitudinal gradient in Lushan Mountains of China.

2011, 22(07):  1675-1681. 

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To understand the spatial distribution characteristics of organic carbon in northern subtropical forest soils along an altitudinal gradient in Lushan Mountains of China, six and five sampling plots with a 200-m interval of elevation and covered by different vegetation types were installed on the southern and northern slopes, respectively in July-August in 2010 to collect soil profiles, with the soil thickness, bulk density, organic carbon content, and organic carbon density of 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, and >40 cm layers measured. The soil organic carbon density was significantly affected by altitude and slope. On northern slope, soil organic carbon content increased with increasing altitude, and had significant negative correlations with soil bulk density and pH value. On southern slope, soil organic carbon content had no obvious variation pattern along the altitudinal gradient and had less correlation with soil bulk density and pH value, but soil organic carbon density decreased with increasing soil depth. The soil organic carbon density on northern and southern slopes was within the range of 7.07-10.34 kg·m^-2 and 6.03-12.89 kg · m^-2, respectively. The larger variation of soil organic carbon density along altitudinal gradient and soil depth on southern slope suggested that the destruction of original vegetation and the establishment of forest plantation could be one of the important factors affecting the spatial distribution of soil organic carbon.

Effects of light intensity on Quercus liaotungensis seed germination and seedling growth.

2011, 22(07):  1682-1688. 

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This paper studied the effects of different shading (55.4%, 18.9%, 5.5%, 2.2%, 0.5%, and 0.3% natural sunlight) on the seed germination and seedling growth of Quercus liaotungensis. The seed germination rate and germination index were the highest (72.5% and 0.22, respectively) at 55.4% natural sunlight, declined with decreasing light intensity, and were the lowest (42.5% and 0.11, respectively) at 0.3% natural sunlight. Strong light had definite delaying effect on the germination. The index of germination vigor increased with decreasing light intensity, being the maximum at 0.5% natural sunlight. The delay of seed germination under strong light could be the selective tradeoff on varied seed fates. Strong light benefited the  basal stem diameter and root system growth and dry mass accumulation of Q. liaotunensis seedling, but resulted in the minimum seedlings height (6.06 cm). Greater morphological plasticity was observed for the seedlings under different shading, which lent support to the higher adaptability of the seedlings to light environment. For example, the specific leaf area, specific shoot length, specific root length, and chlorophyll b and total chlorophyll contents were the maximum at 0.5% natural sunlight, being 142.57 cm²·g^-1, 156.86 cm·g^-1, 271.87  cm·g^-1, 0.07 g·cm^-2, and 0.24 g·cm^-2, respectively, and the minimum at 55.4% natural sunlight, being 44.89 cm²·g^-1, 52.84  cm·g^-1, 101.98  cm·g^-1, 0.04 g·cm^-2, and 0.15 g·cm^-2, respectively. The variation of the  root/shoot ratio of Q. liaotungensis seedlings under different shading could be the effects of the combination of light intensity and water availability.

Spatial distribution characteristics of the biomass and carbon storage of Qinghai spruce (Picea crassifolia) forests in Qilian Mountains.

2011, 22(07):  1689-1694. 

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This paper estimated the biomass and carbon storage and their spatial distributions of Qinghai spruce (Picea crassifolia) forests in Qilian Mountains, based on the field investigation, forest map, and meteorological data, and with the help of GIS technology. In 2008, the biomass of the forests was averagely 209.24 t·hm^-2, with a total biomass of 3.4×10⁷ t. Due to the difference of water and thermal condition, there existed great differences in the biomass of Qinghai spruce within the Mountains. The biomass increased by 3.12 t·hm^-2 with increasing 1° longitude and decreased by 3.8 t·hm^-2 with increasing 1° latitude, and decreased by 0.05t·hm^-2 with the elevation increasing 100 m. The carbon density of the forests ranged from 70.4  to 131.1 t·hm^-2, averagely 109.8 t·hm^-2, and the average carbon density was 83.8 t·hm^-2 for the young forest, 109.6 t·hm^-2 for the middle age forest, 122t·hm^-2 for the near-mature forest, 124.2t·hm^-2 for the mature forest, and 117.1 t·hm^-2 for the over-mature forest. The total carbon storage of Qinghai spruce forests in the study area was 1.8×10⁷ t.

Stem profile model and variable-exponent of Larix gmelinii plantation.

2011, 22(07):  1695-1701. 

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A series of previous taper equations with variable parameters were compared in this study. The model with better fitting results (smaller residual sum of squares and higher correlation index) for Larix gmelinii taper was selected in terms of model fitting statistics (residual sum of squares and correlation index), and five indices for describing the taper were proposed, according to the meanings of variable parameters in the model. Among the taper equations compared, the equation provided by Lee et al. had better fitting effect, and could be used to describe the tapers of L. gmelinii plantation. The five indices including taper rate of root, influence point, ranges of parabolic and paraconic, minimum of variable parameters, and relative height at minimum of variable parameters could be taken as the methods and tools for comparing the tapers. Only moderate stand density (487 plant·hm^-2) provided good quality of larch stem form, compared to both high (870 plant·hm^-2) and low (275 plant·hm^-2) stand density providing poor quality.

Spatiotemporal changes of potential evapotranspiration in Songnen Plain of Northeast China.

2011, 22(07):  1702-1710. 

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Based on the  daily meteorological data from 72 weather stations from 1961-2003, a quantitative analysis was conducted on the spatiotemporal changes of the potential evapotranspiration in the Plain. The Penman-Monteith model was applied to calculate the potential evapotranspiration; the Mann-Kendall test, accumulative departure curve, and climatic change rate were adopted to analyze the change trend of the evapotranspiration; and the spatial analysis function of ArcGIS was used to detect the spatial distribution of the evapotranspiration. In 1961-2003, the mean annual potential evapotranspiration in the Plain was 330-860 mm, and presented an overall decreasing trend, with the  high value appeared in southwest region, low value in surrounding areas of southwest region, and a ring-belt increasing southwestward. The climatic change rate of the annual potential evapotranspiration was -0.21 mm·a^-1. The annual potential evapotranspiration was the highest in 1982, the lowest in 1995, and increased thereafter. Seasonally, the climatic change rate of the potential evapotranspiration in spring, summer, autumn, and winter was -0.19, 0.01, -0.05, and 0.03 mm·a^-1, respectively, suggesting that the potential evapotranspiration had a weak increase in winter and summer and a slight decrease in spring and autumn.

Dynamic variations of soil moisture in Haloxylon ammodendron root zone in Gurbantunggut Desert.

2011, 22(07):  1711-1716. 

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To understand the dynamic variations of soil moisture in the root zone of original Haloxylon ammodendron land is of significance for further understanding the interactions between hydrological processes and vegetations in the Gurbantunggut Desert. By using TDR probes system, this paper measured the volumetric soil moisture content in H. ammodendron land in the southern edge of Gurbantunggut Desert, and analyzed the spatiotemporal distribution of soil moisture in the root zone of H. ammodendron in August 2007-July 2008. There existed ‘wet island’ effect in H. ammodendron root zone. The 0-60 cm soil water storage in the root zone was 1.49 times of that in bare land. Such a difference was greater in summer than in spring and after rainfall than before rainfall. The soil moisture content in the Desert was the richest in spring after snow melting and the lowest in winter, and its annual variation could be divided into three periods, i.e., quick supplement-consumption period in spring (from March to May), slow consumption period in summer and autumn (from June to September), and stable period in winter (form October to next February). Based on wavelet analysis, the soil moisture variation in H. ammodendron  root zone and bare land had a short cycle of 43 and 40 days and a long cycle of 110 and 103 days, respectively. The relatively rich soil moisture content in H. ammodendron root zone could be mainly due to the stem flow water collection, tree canopy shading, and the better water percolating capacity in root zone.

Spatial distribution patterns of soil nutrients and microbes in seasonal wet meadow in Zhalong wetland.

2011, 22(07):  1717-1724. 

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This paper studied the spatial distribution patterns of soil nutrients and biological characteristics and related major affecting factors in seasonal wet meadow in Zhalong wetland. In the meadow, the soil nutrients, microbial communities, and microbial biomass carbon and nitrogen showed an obvious vertical distribution, but the soil enzyme activities had a complicated spatial distribution due to the effects of multi factors. Stepwise linear regression analysis showed that soil microbial biomass carbon and nitrogen had significant positive correlations with soil β-glucosidase, urease, and phosphatase activities (P<0.05), soil organic carbon had significant correlations with soil actinomycetes and soil catalase activity (P<0.05), soil available K, total N, alkali-hydrolyzable N, and C/N ratio were significantly correlated with soil bacteria (P<0.05), actinomycetes (P<0.05), β-glucosidase activity (P<0.05), and microbial biomass nitrogen (P<0.05), respectively, whereas soil total P and pH had no significant correlations with soil microbial activity (P>0.05). Two models, one for soil nutrients evaluation and another for soil microbiological prediction, were constructed by principal component analysis.

Structural characteristics of Artemisia frigid community at different succession stages in Horqin Sandy Land.

2011, 22(07):  1725-1730. 

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Taking space as a substitute for time, this paper studied the species composition and species diversity of Artemisia frigid community at three succession stages in Horqin Sandy Land. The three succession stages were Periploca sepium-A. frigida community, Periploca sepium-A. frigida+A. halodendron community, and A. frigida-Cleistogenes squarrosa community, all dominated by the plants of Compositae, Chenopodiaceae and Gramineae. The species number and family number in the communities and the species number of Gramineae decreased with succession, while the percentages of Compositae and Gramineae species increased. The species diversity of the communities was in the order of P. sepium-A. frigida+A. halodendron > P. sepium-A. frigida >A. frigida-C. squarrosa. No obvious difference was observed in the species composition among the three communities. In the three communities, A. frigida had the highest coverage, and the coverage increased with succession.

Effects of controlled-release fertilizer and organic amendment on the construction of nutrients reserves in Larix olgensis container seedlings.

2011, 22(07):  1731-1736. 

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A 2×2 factorial experiment was conducted to study the effect of fertilization on Larix olgensis container seedlings. 36.36 or 18.18 mg controlled-release fertilizer (CRF) N and 0 or 1.82 g FM organic amendment (OA) per seedling were applied. There were no significant responses to fertilization in the seedling height, collar diameter, biomass, and potassium (K) uptake. Applying FM OA increased the number of first-order lateral roots with a length > 1 cm (P=0.040), the tap root length (TRL) (P=0.012), and the ratio of TRL to seedling height (P=0.008). Comparing with low application rate CRF N, high application rate CRF N increased the N concentration in root (P=0.035) as well as the N reserves in stem (P=0.005), root (P=0.037), and stem plus root (P=0.030), and the P reserves in stem (P=0.047). Applying 36.36 mg CRF N plus 1.82 g FM OA increased the N concentrations in leaf and in stem plus root by 137% (P=0.040)and 21% (P=0.013), respectively, and the N reserves in stem (P=0.020), root (P=0.017), and stem plus root (P=0.013). Vector analysis revealed that high application rate of CRF N led to the excess of seedlings N and P, while applying FM OA alleviated the N and P deficiency but led to the K depletion. For nursing L. olgensis container seedlings, a solution of CRF 18 mg N combined with 1.82 g FM OA per seedling was recommended.

Effects of controlled-release fertilizer on chrysanthemum leaf chlorophyll fluorescence characteristics and ornamental quality.

2011, 22(07):  1737-1742. 

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Taking cut flower chrysanthemum ‘Baima’ as test material, a pot experiment was conducted to study the effects of controlled-release fertilizer on the leaf chlorophyll fluorescence parameters, chlorophyll and nutrient contents, and ornamental quality of chrysanthemum. Under no fertilization, the maximal photochemical efficiency of PSⅡ in dark (F_v/F_m), potential photochemical efficiency of PSⅡ (F_v/F_o), and quantum yield of PSⅡ electron transport (Φ_PSⅡ) decreased significantly, compared with those under fertilization. With the application of conventional compound fertilizers CCFA (N：P：K=20：8：10) and CCFB (N：P：K=14：14：14), the F_v/F_m, F_v/F_o and Φ_PSⅡ had a slight increase in early period (30-60 d) but a remarkable decrease in mid and later periods (75-120 d), compared with those under the application of controlled-release fertilizers CRFA (N：P：K=20：8：10) and CRFB (N：P：K=14：14：14). Under the application of CRFA, the F_v/F_m, Φ_PSⅡ, and photochemical quenching (q_P) had somewhat increase, as compared with the application of CRFB. The non-photochemical quenching (NPQ) under the application of CRFA and CRFB decreased significantly, compared with that under the application of CCFA and CCFB and the control. The chlorophyll content had a similar change trend with F_v/F_m, F_v/F_o , and Φ_PSⅡ. The leaf N, P, and K contents, flower stalk length and stalk diameter, flower diameter, and flower fresh and dry mass at harvest stage all increased under the application of CRFA and CRFB,compared with those under the application of CCFA and CCFB and the control, and the flower fresh and dry mass was significantly higher under the application of CRFA than of CRFB. This study showed that controlled-release fertilizer could improve the ornamental quality of chrysanthemum via improving the leaf chlorophyll content, photochemical transduction rate, and nutrient uptake, and CRFA had better effects than CRFB.

Effects of shading on photosynthesis characteristics of Photinia × frasery and Aucuba japonica var. variegata.

2011, 22(07):  1743-1749. 

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This paper studied the effects of different shading (light transmittance 20%, 40%, 60%, and 100%) on the photosynthesis characteristics of two ornamental foliage plants Photinia × frasery and Aucuba japonica var. variegata. After shading for six weeks, the  net photosynthesis rates of two plants measured ex situ under natural light enhanced, compared to those measured in situ, and, with the increase of shading degree, the net photosynthetic rates had an increasing trend, with the maximum being 9.7 μmol·m^-2·s^-1 for Photinia × frasery and 8.3μmol·m^-2·s^-1 for Aucuba japonica var. variegata. In the meantime, the transpiration rates of the two plants increased significant\ly. Shading increased the chlorophyll a, b, and a+b contents and the chlorophyll/carotenoids ratio, decreased the chlorophyll a/b, but less affected the carotenoids content. The phenotypic plasticity index (PPI) of net photosynthesis rate and transpiration rate of Photinia × frasery and Aucuba japonica var. variegate was 2.08 and 3.21, and 0.55 and 1.60, respectively. The chlorophyll and carotenoids contents of the two plants were relatively stable, indicating the minor influence of external environment factors on pigments. Aucuba japonica var. variegata had a higher shading tolerance than Photinia × frasery.

Effects of conservation tillage on soil water conservation and crop yield of winter wheat-spring maize rotation field in Weibei highland.

2011, 22(07):  1750-1758. 

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A field experiment was conducted in 2007-2010 to study the effects of no-tillage, sub-soiling, and deep-ploughing combined with balanced fertilization, traditional fertilization, and no (or lower amount) fertilization on the soil water storage, crop yield, water use efficiency (WUE), and economic return of winter wheat-spring maize rotation field in Weibei highland. Among the tillage measures, no-tillage in fallow period had the best effect in soil water conservation, followed by sub-soiling, and deep-ploughing. The average water storage in 0-200 cm soil layer in crop growth period under no-tillage and sub-soiling was 6.7% and 1.9% higher than that under deep-ploughing, respectively. Under the balanced, traditional, and no (or lower amount) fertilizations, sub-soiling all showed the highest yield, WUE, and economic return, with the best effect under balanced fertilization. The three-year crop yield under sub-soiling combined with balanced fertilization was 6909, 9689, and 5589 kg·hm^-2, WUE was 18.5, 25.2, and 23.0 kg·hm^-2·mm^-1, and economic return was 5034, 5045, and 7098 yuan·hm^-2, respectively. It was suggested that balanced fertilization combined with sub-soiling had the best effect in soil water conservation and yield- and income increase, being the more appropriate fertilization and tillage mode for the wheat-maize rotation field in Weibei highland.

Effects of different irrigation modes in winter wheat growth season on the grain yield and water use efficiency of winter wheat-summer maize.

2011, 22(07):  1759-1764. 

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Three irrigation modes in winter wheat growth season were carried out in Heilonggang basin of North China Plain to investigate their effects on the grain yield, water consumption, and water use efficiency (WUE) of winter wheat-summer maize. The three irrigation modes included irrigation before sowing (75 mm, W₁), irrigation before sowing and at jointing stage (75 mm+90 mm, W₂), and irrigation before sowing, at jointing stage, and at filling stage (75 mm+90 mm+60 mm, W₃). With the irrigation modes W₂ and W₃, the increment of the annual yield of winter wheat-summer maize was 8.7% and 12.5% higher than that with W₁, respectively. The water consumption in winter wheat growth season decreased with increasing irrigation amount, while that in summer maize growth season increased with the increasing irrigation amount in winter wheat growth season. The WUE of winter wheat with the irrigation mode W₂ was 11.1% higher than that with W₃, but the WUE of summer maize had less difference between irrigation modes W₂ and W₃. The annual WUE (WUE_T) of W₂ and W₁ was 21.28 and 21.60 kg^-1·mm·hm^-2, being 7.8% and 9.4% higher than that of W₃, respectively. Considering the annual yield, water consumption,and WUE, irrigation mode W₂ could be the advisable mode for water-saving and high-yielding.

Dynamic simulation of wheat stem-sheath angle based on process.

2011, 22(07):  1765-1770. 

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Based on the field experiments with different plant-type wheat (Triticum aestivum) cultivars and varied population densities, the time-course changes in the angle between stem and sheath (stem-sheath angle) on main stem were observed, and a process-based model was developed for simulating the growth dynamics of stem-sheath angle on the main stem by using system analysis method and dynamic modeling technology. The stem-sheath angle increased with the growth of corresponding leaves, and decreased with increasing population density. The maximum stem-sheath angle decreased with increasing leaf position, except for the first leaf on main stem. The growth dynamics of stem-sheath angle could be described with Logistic equation, and the changes in the maximum stem-sheath angle with leaf position could be quantified with two different equations. The maximal value of stem-sheath angle at the second leaf position was considered as the cultivar parameter to reflect the genetic differences, and the plant number per unit area was used to quantify the effects of population density. The independent field experiment dataset of different wheat cultivars was used to test the model, and the average RMSE between estimated and observed values was 1.7°, suggesting that the present model had good performance and reliability on predicting the growth dynamics of wheat stem-sheath angle, and provided a key module for wheat plant-type simulation and visualization.

Diurnal variation of gas exchange and chlorophyll fluorescence parameters of cotton functional leaves under effects of soil salinity.

2011, 22(07):  1771-1781. 

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A two-year (2007-2008) pot experiment with cotton varieties Sumian 12 (salinity-sensitive) and Zhongmiansuo 44 (salinity-tolerance) was conducted at the Pailou experimental station of Nanjing Agricultural University to study the diurnal variation of the gas exchange and chlorophyll fluorescence parameters of cotton functional leaves under five levels (0, 0.35%, 0.60%, 0.85%, and 1.00%) of soil salinity. With the increase of soil salinity, the concentrations of Na⁺, Cl^-, and Mg²⁺ in functional leaves increased, whereas the concentrations of K⁺ and Ca²⁺ decreased. The salinity level <0.35% had little effects on the gas exchange and chlorophyll fluorescence parameters, but that >0.35% depressed the net photosynthetic rate (P_n) dramatically. At the salinity level >0.35%, the sensitivity of functional leaves to daytime photon flux density (PFD) and air temperature (T_a) enhanced, which in turn resulted in more severe photo- and temperature inhibition, and changed the diurnal variation patterns of P_n and stomatal conductance (G_s) from a one-peak curve to a constantly decreasing one. Along with the variations of daytime PED and T_a, the diurnal variation patterns of the maximum photochemical efficiency (F_v/F_m), quantum yield of electron transport (Φ_PSⅡ）), and photochemical quenching coefficient (q_P) of functional leaves presented a V-shaped curve, with the minimum value appeared at 12:00-13:00, while the non-photochemical quenching coefficient (q_N) showed a single-peak curve. Soil salinity decreased the F_v/F_m, Φ_PSⅡ）,and q_P significantly, but increased the q_N and enlarged its change trend. The comparatively low concentrations of Na⁺ and Cl^- and the relatively high concentrations of K⁺and Ca²⁺ in salt-tolerant Zhongmiansuo 44 functional leaves benefited the relative stability of PSⅡ, and the maintenance of a relatively high thermal dissipation capacity could be one of the reasons for a high level of P_n at high salinity level.

Ear shape of corn and its relations to grain yield under stress.

2011, 22(07):  1782-1788. 

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To quantify the ear shape of corn (Zea mays L.) and to understand the effects of growth stress on the ear shape are of importance in corn crop science. By means of digital image analysis on whole ear RGB images, and using the definition of extent (E), volumetric odds (V), longitudinal centroid (L),　transverse centroid (T), and sphericity (S) to represent the similarity to rectangle, volumetric equality, longitudinal symmetry, transverse symmetry, and similarity to sphere, respectively, the ear shape data from the field experiment with 2 corn cultivars, 2 contrast growth conditions, and 2 defoliation treatments in a split plot design were analyzed by cluster analysis, canonical variate analysis, and variance analysis. It was found that within the first 2 weeks after silking, the ear shape varied obviously, namely, the E increased from 0.72 to 0.78, the S from 0.40 to 0.48, while the L decreased from 0.56 to 0.51, the T decreased from 0.02 to 0.01, and the V decreased from 0.25 to 0.21. Afterwards, all the 5 shape traits tended to be stable. Growth stress (high planting density and zero fertilizer application) shifted the E by -4.5% and the V by +17.7% at maturing stage, which, combined with the variation of ear length and width, contributed 87%-97% of grain yield change. Throughout the ear growth duration, the ear shape traits L, V, and S were more sensitive to growth stress, being considered as the potential quantitative indicators of stress.

Root activity and photosynthetic characteristics of Elaeagnus oxycarpa  seedlings under drought stress.

2011, 22(07):  1789-1795. 

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Taking one-year old Elaeagnus oxycarpa seedlings as test materials, this paper studied their root activity and leaf cell membrane permeability, relat\ive water content, photosynthetic pigment contents, and photosynthetic parameters at different soil relative moisture contents under natural drought condition. When the soil relative moisture content decreased from 70% (CK) to 40%, the E. oxycarpa seedlings root activity and net photosynthetic rate increased gradually and reached their maximum (1178 μg·g^-1·h^-1 and 21.9 μmol·m^-2·s^-1, respectively), photosynthetic pigment contents increased stably, transpiration rate and water use efficiency did not show any significant difference, and cell membrane permeability kept at a low level.When the soil relative moisture content decreased from 40% to 20%, the leaf relative water content was still higher than 50%, cell membrane permeability maintained at a low level, root activity and photosynthetic pigment contents remained high, and other photosynthesis parameters decreased slowly. When the soil relative moisture content decreased from 10% to 5%, the cell membrane permeability increased acutely, but the leaf relative water content, total chlorophyll content, all photosynthesis parameters, and root activity had a significant decrease. The water use efficiency reached the peak when the soil relative moisture content was 10%. To sum up, the optimal soil relative moisture content for E. oxycarpa seedlings should be 40%-50%, and the permanent wilting coefficient of the seedlings was 4.3% (soil relative moisture content).

Effects of sulfur starvation on the non-protein thiol content and glutathione S-transferase activity of rice seedlings under cadmium stress.

2011, 22(07):  1796-1802. 

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By installing a treatment of sulfur starvation, this paper studied the dynamic changes of rice seedling growth, cadmium (Cd) and non-protein thiol (NPT) contents, and glutathione S-transferase (GST) activity under Cd stress. Cd stress inhibited the seedling growth obviously, induced the synthesis of sulfhydryl (-SH) compounds, including non-protein thiol, glutathione, and phytochelatins, and made the GST activity decreased after an initial increase. Sulfur starvation somewhat increased the Cd uptake and translocation, but less affected the impacts of Cd stress. The contents of -SH compounds decreased, and the GST activity in root increased. It was suggested that the roles of -SH compounds and GST in Cd-resistance of rice were complementary, being able to alleviate the Cd toxicity to some extent.

Silkworm excrement organic fertilizer: Its nutrient properties and application effect.

2011, 22(07):  1803-1809. 

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In this paper, silkworm excrement was harmless-treated via controlled fermentation to prepare silkworm excrement organic fertilizer (SEOF). The nutrient properties of the SEOF were determined, and a pot experiment was conducted to examine the application effect of the fertilizer. After fermentation, the total N, P, and K contents in the SEOF had a significant increase, being 58.0%, 84.4%, and 29.7% higher than those in the raw material, respectively. The addition of microbial inoculants shortened the fermentation period, and decreased the carbon and nitrogen losses during fermentation. With the application of SEOF, the seed germination index of cabbage and tomato was higher than 80%, suggesting that the fertilizer had no inhibitory effect on the seed germination. The application of SEOF not only increased the Chinese cabbage yield and its nutrients and Vc contents, decreased the plant nitrate content, but also improved the soil pH value, and increased the soil available nutrients and organic matter contents and soil enzyme activities, with better effect than applying composted goat feces.

Sources and potential risk of heavy metals in roadside soils of Xi’an City.

2011, 22(07):  1810-1816. 

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Based on the X-Ray fluorescence spectroscopic measurement of heavy metals concentration in roadside soil samples from Xi’an City, and by the methods of principal component analysis, cluster analysis, and correlation analysis, this paper approached the possible sources of heavy metals in the roadside soils of the City. In the meantime, potential ecological risk index was used to assess the ecological risk of the heavy metals. In the roadside soils, the mean concentrations of Co, Cr, Cu, Mn, Ni, Pb, and Zn were higher than those of the Shaanxi soil background values. The As, Mn and Ni in roadside soils mainly came from natural source and transportation source, the Cu, Pb, and Zn mainly came from transportation source, and the Co and Cr mainly came from industry source. These heavy metals in the roadside soils belonged to medium pollution, and had medium potential ecological risk.

Changes of China agricultural climate resources under the background of climate change. VII. Change characteristics of agricultural climate resources in arid and semi-arid region of Tibet Plateau.

2011, 22(07):  1817-1824. 

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Based on the 1961-2007 ground observation data from 55 meteorological stations in arid and semi-arid region of Tibetan Plateau, and by using 5-day moving average method and ArcGIS-IDW module, this paper analyzed the spatiotemporal change characteristics and climatic trend rates of agricultural climate resources in the region in 1961-1980 (period I) and 1981-2007 (period II). In 1961-2007, the sunshine duration during the growth season of chimonophilous crops in the study region changed less, while that during the growth season of thermophilic crops increased but with little spatial change. Comparing with those in period I, the average value of accumulated temperature in period II showed an increasing trend, and the area with ≥1500 ℃·d during the growth season of thermophilic crops increased by 33.9%. The precipitation decreased gradually from southeast to northwest. During the growth season of chimonophilous crops, the precipitation in the southeast in the two periods reached 800 mm, but the climatic trend in other areas was positive or negative, and the change rate was small. The area with precipitation ≥ 400 mm during the growth season of thermophilic crops in period II expanded by 40%, as compared in period I. The reference crop evapotranspiration (ET₀) generally increased slightly, and shared the similar spatial distribution pattern with sunshine duration and accumulated temperature. During the growth season of thermophilic crops, the area with ET₀≥ 400 mm in period II expanded by 35.7%, compared with that in period I. In the study period, the heat and precipitation resources during crop growth seasons in Tibet Plateau increased in a certain degree, which was very beneficial to the agriculture-stock production. However, the increase of reference crop evapotranspitation indicated the increase of potential evaporation. Thereby, the researches about the possible effects of climate change on agriculture-stock production should be further strengthened.

Spatiotemporal variation of typical red soil eroded landscape pattern: A case study in Changting County of Fujian Province.

2011, 22(07):  1825-1832. 

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Based on the 1988, 2000, and 2007 remote sensing images of a typical red soil eroded region (Changting County, Fujian Province) and the digital elevation model (DEM), the eroded landscape types were worked out, and the changes of the eroded landscape pattern in the region from 1988 to 2007 were analyzed with the spatial mathematics model. In 1988-2007, different eroded landscape types in the region had the characteristics of inter-transfer, mainly manifested in the transfer from seriously eroded to lightly eroded types but still existed small amount of the transference from lightly eroded to seriously eroded types. Little change was observed in the controid of the eroded landscape. In the County, Hetian Town was all along the eroded center. During the study period, the landscape pattern index showed a tendency of low heterogeneity, low fragmentation, and high regularization at landscape level, but an overall improvement and expansion of lightly eroded and easy-to-tackle patches as well as the partial improvement and fragmentation of seriously eroded and difficult-to-tackle patches at patch level.

Changes of wetland landscape pattern in Dayang River Estuary based on high-resolution remote sensing image.

2011, 22(07):  1833-1840. 

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Based on the comprehensive consideration of the high resolution characteristics of remote sensing data and the current situation of land cover and land use in Dayang River Estuary wetland, a classification system with different resolutions of wetland landscape in the Estuary was established. The landscape pattern indices and landscape transition matrix were calculated by using the high resolution remote sensing data, and the dynamic changes of the landscape pattern from 1984 to 2008 were analyzed. In the study period, the wetland landscape components changed drastically. Wetland landscape transferred from natural wetland into artificial wetland, and wetland core regional area decreased. Natural wetland’s largest patch area index descended, and the fragmentation degree ascended; while artificial wetland area expanded, its patch number decreased, polymerization degree increased, and the maximum patch area index had an obvious increasing trend. Increasing human activities, embankment construction, and reclamation for aquaculture were the main causes for the decrease of wetland area and the degradation of the ecological functions of Dayang River Estuary. To constitute long-term scientific and reasonable development plan, establish wetland nature reserves, protect riverway, draft strict inspective regimes for aquaculture reclamation, and energetically develop resource-based tourism industry would be the main strategies for the protection of the estuarine wetland.

An integrated assessment method of ecological quality status in coastal waters: Taking Tong’an Bay as a case.

2011, 22(07):  1841-1848. 

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Based on the integrated assessment methods of ecological quality status (EcoQS) in coastal waters abroad as well as the domestic related research status, 11 indices were selected from the biotic and physicochemical elements of water and sediment to built an integrated EcoQS assessment index system, and, with the comprehensive consideration of domestic and international evaluation standards, 5 levels of EcoQS classified as “high, good, moderate, poor, and bad” were determined. Then, an integrated assessment method of EcoQS in coastal waters was established by using analytic hierarchy process (AHP) and fuzzy mathematics method, and tested by the analysis of the correlations between the EcoQS grade and the major anthropogenic disturbances and pollutant concentrations of Tong’an Bay. The EcoQS of Tong’an Bay was assessed as moderate, i.e., the Bay was moderately disturbed and in transitional to poor status. The established integrated assessment method could not only reflect the major anthropogenic environmental pressure and risk factors, but also give an early warning of the pollutants satisfied by law in the study area.

Urban habitants’ attitudes toward nature-approximating landscape architecture: Taking Hongshan District of Wuhan City, China as a case.

2011, 22(07):  1849-1856. 

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Nature-approximating landscape architecture (NALA) is a concept of sustainable development as applied to landscape architecture, while the urban habitants’ awareness and acceptance of NALA idea is the key for the successful application of NALA. Through semi-structured interview, this paper explored the attitudes of the habitants in Hongshan District of Wuhan City toward the NALA design and management, and the influence of the social-economic characteristics of the responders on their attitudes toward the NALA. A fairly low percentage of the responders approved of the NALA design (10.3%-46.9%) and management (7.4%-34.9%). The attitudes towards NALA design were mainly affected by the responders’ age, and the attitudes toward NALA management were significantly correlated with the responders’ age, educational level, and profession. The efficient cause why a large number of responders did not support the NALA was that these responders attached importance to the aesthetic effect of green space, and preferred cleanliness and order. The lack of related ecological knowledge and environmental awareness was the root cause of the lesser support towards NALA. To establish NALA demonstration bases and to intensify the publicity and education of NALA idea and related ecological knowledge could promote an increasing number of urban habitants actively participating in NALA construction.

Identification and degradation capability of three pyrene-degrading Gordonia sp. strains.

2011, 22(07):  1857-1862. 

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Three pyrene-degrading bacterial strains named D44, D82S and D82Q were isolated from PAHs-contaminated soil in Shenfu Irrigation Area of Shenyang, Northeast China. The strains were identified as Gordonia sp., based on the morphological observation, physiological and biochemical identification, and phylogenetical analysis of 16S rDNA sequences. For all the three stains, their optimal pH was 7, and their growth was obviously inhibited when the pH was lower than 5 or higher than 9. The three strains were capable of utilizing pyrene, benzo［a］pyrene, anthracene, naphthalene, phenanthrene, and fluoranthene as the sole source of carbon and energy. After seven days incubation, the three strains could degrade more than 65% of pyrene with an initial concentration 100 mg·L^-1, and the D44, D82S, and D82Q could degrade 79.6%, 91.3%, and 62.8% of benzo［a］pyrene with an initial concentration 50 mg·L^-1, respectively. PCR amplification indicated that the strains D82Q and D82S possessed alkane monooxygenase gene alkB.

Impact of Mikania micrantha invasion on soil meso- and micro-invertebrate community structure.

2011, 22(07):  1863-1870. 

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Mikania micrantha, a notorious exotic weed of Asteraceae family, has invaded successfully in southern China, and caused serious damages to native ecosystems. In this paper, a field survey was conducted in the Huolushan Forest Park of Guangzhou, China, aimed to understand the impact of M. micrantha invasion on the soil meso- and micro-invertebrate community. Three sampling sites were installed, including M. micrantha-invaded site, ecotone, and native vegetation site. Through four samplings in 2009, a total of 5206 soil meso- and micro-invertebrate individuals were collected, belonging to 4 phyla, 10 classes, and 19 orders, among which, Nematoda was the dominant group, and Acarina, Collembolan, and Rotifera were the common groups. M. micrantha invasion altered the characteristics of soil meso- and micro-invertebrate community structure. Compared with those at the other two sampling sites, the numbers of total individuals, Nematoda, and Acarina at M. micrantha-invaded site increased significantly, but the groups of soil meso- and micro-invertebrates had less change. At M. micrantha-invaded site, the density-group index (DG) of soil meso- and micro-invertebrates was significantly higher, Margalef richness index (D) and Simpson dominance index (C) tended to ascend, but Pielou evenness index (E) and Shannon index (H′) tended to descend. The similarity coefficient of soil meso- and micro-invertebrate community between M. micrantha-invaded site and ecotone was higher than that between M. micrantha-invaded site and native vegetation site. The changes of local climate conditions, plant litters, root secretions, and soil physical-chemical properties caused by M. micrantha invasion could be the major contributing factors that altered the community structure of soil meso- and micro-invertebrates at M. micrantha-invaded site.

Responses of Caragana seed pests to host plant patch quality and patch pattern in desert regions of Ningxia, Northwest China.

2011, 22(07):  1871-1877. 

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Taking the desert landscape in mid-eastern Ningxia of Northeast China as the background, eighteen patches of Caragana shrub lands (natural or manned) with the habitat types of manually-fixed sandy land, mobile sandy land, and silty-loam downland were selected as study sites to investigate the responses of three Caragana seed pest species (Kytorhinus immixtus, Etiella zinckenella, and Bruchophagus neocaraganae) to the host plant patch quality, patch area, and patch spatial pattern. The damaged rate of host plant by the pests had close relations to the patch quality, patch pattern, and the transferring capability of the pests. The responses of the pests to patch quality were affected by patch scale, and among the three habitat types, manually-fixed sandy land had the highest damaged rate, followed by mobile sandy land, and silty-loam downland, with significant differences among them (P<0.05). In small scale patch pattern, there existed definite correlations between the pest number and the patch area and its fragmentation degree. The decrease of patch area and the increase of the fragmentation degree reduced the damage rate of high transferring capability Etiella zinckenella (r=0.365), but had less effects on low transferring capability K. immixtus (r=0.160) and B. neocaraganae (r=0.193). The strength of patch edge effect and the mutual complement of the resources around patches had positive effects on the population density of the pests.

Effects of di-n-butyl phthalate on the antioxidant enzyme activities and lipid peroxidation level of Perna viridis.

2011, 22(07):  1878-1884. 

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A laboratory experiment was conducted to examine the superoxide dismutase (SOD) and catalase (CAT) activities and the lipid peroxidation (LPO) level presented by malondialdehyde (MDA) in visceral mass and mantle of green mussel (Perna viridis) after exposure to 0.5- 62.5 mg·L^-1 of di-n-butyl phthalate (DBP) for 15 days, and to study the change characteristics of these biochemical indicators after the green mussel released into DBP-free seawater for 10 days. During exposure period, the SOD activity in visceral mass was inhibited first and then reached the level of the control at 0.5 and 2.5 mg·L^-1 of DBP, but inhibited significantly (P<0.01) at 12.5 and 62.5 mg·L^-1 of DBP. The CAT activity in visceral mass was inhibited at all test concentrations of DBP, while the LPO level was obviously induced. During the chronic DBP exposure, the SOD and CAT activities in the mantle were induced significantly but had no regular pattern, and the LPO level was also obviously induced. After the exposed green mussel was released into clean seawater, the SOD and CAT activities in the visceral mass in 12.5 and 62.5 mg DBP·L^-1 groups recovered much slowly, but the LPO level gradually recovered to control level. During the recovery period, the SOD activity in the mantle showed an increasing trend with time, but the CAT activity and LPO level reached gradually to the level of the control.

Macrozoobenthos functional groups in intertidal flat of northwest Jiaozhou Bay.

2011, 22(07):  1885-1892. 

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Based on the survey of macrozoobenthos at 35 locations of 7 sections in the intertidal flat of northwest Jiaozhou Bay in February, May, August, and November 2009, three zones including high tidal zone (A), mid tidal zone (B, C, and D), and low tidal zone (E) were selected to study the functional groups of macrozoobenthos in the flat. A total of 71 macrozoobenthos species were recorded, most of which were of mollusk (31 species), polychaete (20 species), and crustacean (14 species). The species number in A, B, C, D, and E was 26, 33, 35, 38, and 31, respectively. According to their food preferences, the macrozoobenthos were classified into 4 functional groups, i.e., planktonphagous, carnivorous, omnivorous, and detritivorous. The percentage of the species number of each functional group in the total species number of macrozoobenthos was in the order of carnivorous > planktophagous > detritivorous > omnivorous. Carnivorous group had the highest species diversity index, while omnivorous group had the lowest one. Overall, the species richness index, evenness index, and species diversity index were higher in mid tidal zone and lower in high and low tidal zones. The present study showed that the distribution of macrozoobenthos functional groups varied with the environment of tidal zones, being an integrative reflection of their habitat conditions.

Correlation and path analyses of phenotypic traits and body mass of transgenic carp with growth hormone gene of salmon.

2011, 22(07):  1893-1899. 

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Thirty 2-year old transgenic carp individuals with growth hormone gene of salmon were randomly selected to study the affecting degree of their phenotypic traits on their body mass by the methods of correlation and path analyses, with 30 individuals of non-transgenic carp as the control, aimed to ascertain the main phenotypic parameters affecting the body mass of the transgenic and non-transgenic carps. The test phenotypic traits were total length, body length, body height, least height of caudal peduncle, length of caudal peduncle, length of head, snout length, eyes horizontal diameter, inter-orbital distance, and body depth. Correlation analysis showed that for both of the transgenic and non-transgenic carps, most of the test phenotypic parameters were significantly correlated to body mass (P<0.01). Path analysis indicated that for transgenic carp, its body length and body height were the main predictable factors affecting body mass, with the path coefficient being 0.572 and 0.415, respectively, while for non-transgenic carp, its body depth and tail length were the main predictable factors affecting body mass, with the path coefficient being 0.610 and 0.377, respectively.

Responses of biological markers of larval Propsilocerus akamusi to phenol.

2011, 22(07):  1900-1906. 

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Taking the 4th-instar larval Propsilocerus akamusi as test object, this paper studied the acute toxicity of phenol, and the body mass, pupation rate, protective enzyme activities, and detoxifying enzyme activities of the larvae under exposure to phenol. The LC₅₀ value of phenol to the larvae after exposure for 6, 24, 48, 72, and 96 h was 222.52, 134.86, 67.74, 47.39, and 35.76 mg·L^-1, respectively, and the dry mass, fresh mass, and pupation rate of the larvae decreased under the exposure of 0.4, 4, and 40 mg phenol·L^-1. During 72 h exposure to phenol, the larval catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and carboxylesterase (CarE) activities responded to phenol in concentration- and time-dependent way, while the acid phosphatase (ACP) and alkaline phosphatase (ALP) activities responded slowly and were only inhibited significantly under the exposure to 40 mg·L^-1 of phenol for 48 and 72 h, respectively. It was suggested that the body mass, pupation rate, and CAT, SOD, GST, and CarE activities of 4th-instar larval P. akamusi could be used as the biological markers to monitor the phenol pollution of water body.

Suitability evaluation of great bustard (Otis tarda)’s wintering habitat in Baiyangdian basin.

2011, 22(07):  1907-1913. 

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Based on the related researches of great bustard’s wintering habitat selection as well as the advices of related experts and the distribution records of great bustard in Baiyangdian basin, 3 first class indices and 13 second indices were chosen to characterize the key factors affecting the wintering habitat selection of great bustard, and a habitat quality evaluation model was built to assess the quality of wintering habitat selection of great bustard in Baiyangdian basin. In 2005, the suitable wintering habitats of great bustard in the basin had an area of 11907.25 km², accounting for 34.1% of the total. Of the suitable wintering habitats, the most suitable habitats had an area of 4596.25 km², only 13.2% of the total and comparatively concentrated in two zones, i.e., Baiyangdian Wetland Natural Reserve and its peripheral area (zone I) in the east of Baiyangdian basin, and Xingtang and Quyang counties (zone II) in the southwest of Baiyangdian basin. The total area of the most suitable habitats in zone I and zone II was 2803.55 km², accounting for 61.0% of the most suitable habitats in the basin. To protect the wintering habitat of great bustard in the basin, proper measures should be taken according to the environmental features of the two zones.

Avian diversity and bird strike risk at Fuyang Airport.

2011, 22(07):  1914-1920. 

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From June 2008 to January 2010, a survey of avian communities was conducted in  five habitats (grassland, farmland, town, wetland, and woodland) at Fuyang Airport and its surrounding areas, with the diversity indices in different seasons and different habitats analyzed. A total of 122 avian species belonging to 15 orders and 40 families were recorded. At Fuyang Airport, the avian species number was significantly higher in summer and autumn than in winter and spring, the avian density was the highest in autumn, and the Shannon diversity index and Pielou evenness index were the highest in summer. Among the five habitats at the Airport and its surrounding areas, woodland had the greatest avian species number and density, and the woodland, wetland, and farmland had higher Shannon diversity index than grassland and town. The most dangerous avian species to the airplanes at Fuyang Airport were Passer montanus, Pycnonotus sinensis, Hirundo rustica, Columba livia f. domestica, Pica pica, Streptopelia chinensis, and Sturnus cineraceu.

Soil organic carbon fractionation methods and their applications in farmland ecosystem research: A review.

2011, 22(07):  1921-1930. 

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Soil organic carbon is of heterogeneity in components. The active components are sensitive to agricultural management, while the inert components play
 an important role in carbon fixation. Soil organic carbon fractionation mainly includes physical, chemical, and biological fractionations. Physical fractionation is to separate the organic carbon into active and inert components based on the density, particle size, and its spatial distribution; chemical fractionation
is to separate the organic carbon into various components based on the solubility, hydrolizability, and chemical reactivity of organic carbon in a variety of extracting agents. In chemical fractionation, the dissolved organic carbon is bio-available, including organic acids, phenols, and carbohydrates, and the acid-
hydrolyzed organic carbon can be divided into active and inert organic carbons. Simulated enzymatic oxidation by using KMnO₄ can separate organic carbon into active and non-active carbon. Biological fractionation can differentiate microbial biomass carbon and potential mineralizable carbon. Under different farmland management practices, the chemical composition and pool capacity of soil organic carbon fractions will have different variations, giving different effects on soil quality. To identify the qualitative or quantitative relationships between soil organic carbon components and carbon deposition, we should strengthen the standardization study of various fractionation methods, explore the integrated application of different fractionation methods, and sum up the most appropriate organic carbon fractionation method or the appropriate combined fractionation methods for different farmland management practices.

Ecological design of ditches in agricultural land consolidation: A review.

2011, 22(07):  1931-1938. 

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Agricultural land consolidation is a strong disturbance to farmland ecosystem. In traditional agricultural land consolidation, the main technical and economic indices for the design of ditches include the convenience for production and transportation, the allocation of water resources, and the improvement of water utilization, but short of ecological consideration, which has already affected the spread of agricultural species, caused the degradation of bio-habitat, and given obvious negative effects on the bio-competition mechanism, buffering and compensation capacity, and insect pests-resistance of farmland ecosystem. This paper summarized the functions of ecological ditches, and introduced the recent progress on the formations and construction designs of ecological ditches, tests of ecological engineering methods, and technologies and methods of choosing correct ecological materials. It was suggested that the future research should focus on the different functional requirements and specifications for different roads and ditches, and the characteristics and habitats of all the organisms and animals should be considered by the designers and constructors. Moreover, a comprehensive design which meets the ecological demands for the ditches’ formations, structures, and regulatory sizes should be taken into account to solve the most of the problems listed above.

Colonization and community structural features of AM fungi in urban ecosystem: A
 review.

2011, 22(07):  1939-1943. 

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Arbuscular mycorrhizal (AM) fungi, an important component of soil microbes, are of significance in maintaining the sustainable development of urban ecosystem. This paper summarized the characteristics of the colonization and community structure of AM fungi in urban ecosystems, and discussed the effects of urban  ecological factors, e.g., human activities, vegetation re-establishment and maintenance, and urban soil status, on the colonization and community structure. It was considered that the researches on the community structure and function of AM fungi in urban ecosystems, such as the effects and mechanisms of the key urban ecological factors (e.g., water resource shortage and heat island effect) on the alternation of AM fungal community structure should be strengthened in the future.

Control effects of mowing in combining with planting tree species on Chromolaena odorata in Karst region of Guangxi, China.

2011, 22(07):  1944-1948. 

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A field experiment was conducted in 2006-2008 to evaluate the control effects of three mowing frequencies in combining with planting three tree species with three densities on the Chromolaena odorata in southwestern Karst region of Guangxi. In all treatments, the relative coverage, height, density, and aboveground biomass of C. odorata were decreased by 89.7%-99.3%, 41.6%-81.2%, 61.4%-83.2% and 91.7%-97.8%, respectively, and the capitulum number was significantly lesser than that in the control (P<0.05). The control effects on the growth of C. odorata were in the order of mowing frequency > tree species > planting density, and the optimal control mode was mowing twice one year and planting four plants of Delavaya yunnanensis per plot (4 m×4 m).