Table of Content

18 October 2011, Volume 22 Issue 10

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Articles

Effects of irrigation  on the water soluble carbohydrate contents in different wheat cultivars stem and sheath and the grain yield.

2011, 22(10):  2487-2494. 

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Taking two wheat (Triticum aestivum L.) cultivars Jimai 20 and Taishan 22 as test objects, this paper studied the effects of different irrigation treatments on the water soluble carbohydrate contents in penult stem internode and sheath and the grain yield. Four irrigation treatments were installed, i.e., no irrigation (W₀）, irrigation at overwintering and jointing stages (W₁), irrigation at overwintering, jointing and anthesis stages (W₂), and irrigation at overwintering, jointing, anthesis and filling stages (W₃). In treatment W₀, the contents of total soluble sugar and of fructan with the degree of polymerization (DP) ≥4 and =3 in the penult stem internode and sheath of the two cultivars at early filling stage and the fructose content at later filling stage were the highest, indicating that the accumulation and degradation of water soluble carbohydrate in the penult stem internode and sheath were promoted under no irrigation, which in turn increased the 1000-grain weight. In treatment W₁, the contents of fructan with DP≥4 and DP=3 in the penult stem internode and sheath of Jimai 20 at early filling stage, the total soluble sugar and fructose contents at middle and later filling stages, and the grain yield were the highest. In treatment W₂, Taishan 22 had the highest contents of fructan with DP≥4 and DP=3 in the penult stem internode and sheath at early filling stage, lower fructose content at higher filling stage than in treatment W₁, and the highest grain yield. Comparing with Jimai 20, Taishan 22 had higher contents of total soluble sugar and of fructan with DP≥4 in the penult stem internode and sheath at early filling stage and higher  content of fructose at later filling stage, and lower  grain yield in treatments W₀and W₁ but higher grain yield in treatments W₂ and W₃. In this study, treatments W₁ and W₂ promoted the accumulation and degradation of water soluble carbohydrate in the penult stem internode and sheath of Jimai 20 and Taishan 22, and gained the highest grain yields of the two cultivars, respectively, being most appropriate irrigation treatments for Jimai 20 and Taishan 22, respectively.

Effects of supplemental irrigation based on measuring soil water content on wheat photosynthetic characteristics and dry matter accumulation and allocation.

2011, 22(10):  2495-2503. 

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Taking high-yielding winter wheat cultivar Jimai 22 as test material, a field experiment was conducted to study the effects of supplemental irrigation based on measuring soil water content on the wheat photosynthetic characteristics and dry matter accumulation and allocation. Six treatments were installed, i.e., W₁(soil relative water content was 65% at jointing stage and was 70% at anthesis), DW₁(soil relative water content was 65% 10 d after jointing and was 70% at anthesis), W₂(soil relative water content was 75% at jointing and was 70% at anthesis), DW₂ (soil relative water content was 75% 10 d after jointing and was 70% at anthesis), W₃(soil relative water content was 80% at jointing stage and was 70% at anthesis), and DW₃(soil relative water content was 80% 10 d after jointing and was 70% at anthesis).In treatments W₂ and DW₂, the flag leaf photosynthetic rate (P_n) and Ф_PSⅡ at late filling stage were higher than those in treatments W₃ and DW₃, respectively, the dry matter accumulation amount at anthesis and maturity stage and the allocation of accumulated dry matter at pre-anthesis to grain were significantly higher than those in treatments W₁ and DW₁, and the water use efficiency (WUE) and irrigation production efficiency (IPE) were significantly higher than those in W₃ and DW₃. Under the same irrigation levels, the flag leaf P_n and Ф_PSⅡat late filling stage were higher in treatments DW₂ and DW₃ than in W₂and W₃, respectively, and the dry matter accumulation amount at anthesis and its allocation to grain were lower whereas the dry matter accumulation amount after anthesis, the grain yield, WUE, and IPE were higher in DW₂ and DW₃ than in W₂ and W₃. Under our experimental condition, DW₂ could be the optimal irrigation pattern of high-yielding with high WUE.

Effects of shading at different phases of grain-filling on wheat grain protein components contents and processing quality.

2011, 22(10):  2504-2510. 

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Taking three wheat cultivars Jimai 20 (strong gluten), Taishan 23 (medium gluten), and Ningmai 9 (weak gluten) as test materials, a field experiment was conducted to examine the effects of shading at different phases of grain-filling on the grain protein components contents and processing quality. Four treatments were installed, i.e., no shading (S₀), shading at early grain-filling phase (from 0 day after anthesis (DAA) to 11 DAA; S₁), shading at medium grain-filling phase (from 12 DAA to 23 DAA; S₂), and shading at late grain-filling phase (from 24 DAA to 35 DAA; S₃). No significant differences were observed in the grain albumin+globulin contents of the three cultivars among the four treatments. Shading increased the grain HMW-GS, LMW-GS, gluten, glutenin, and total protein contents of Jimai 20 and Taishan 23 significantly, and the increments were higher in treatment S₂ than in other shading treatments. Treatments S₂ and S₃ increased the grain protein components contents of Ningmai 9 significantly. Comparing with the control, shading decreased the grain yield significantly, but increased the dough development time, dough stability time, and sedimentation volume, especially for treatment S₂ , which suggested that the wheat grain quality had a close relationship with the light intensity at medium phase of grain-filling. Overall, the regulation effect of shading at grain-filling stage on the wheat grain yield, grain protein components contents, and indices values of grain processing quality for the test cultivars was in the order of Jimai 20 > Taishan 23 > Ningmai 9.

Effects of irrigation mode on winter wheat yield and water- and nutrient use efficiencies under maize straw returning to field.

2011, 22(10):  2511-2516. 

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In 2008-2010, a field experiment was conducted to study the effects of different irrigation modes on the grain yield, dry matter translocation, water use efficiency (WUE), and nutrient use efficiency (NUE) of winter wheat under maize straw returning to the field in a semi-arid and semi-humid monsoon region of Linfen, Shanxi Province of Northwest China. Irrigation at wintering time promoted tillering, irrigation at jointing stage increased the total tiller number and the fertile spike rate per tiller, whereas irrigation at booting stage promoted the dry matter accumulation in spike and increased the 1000-kernel mass. When the irrigation was implemented at two growth stages and the second irrigation time was postponed, both the dry matter translocation to leaf and the kernels per spike increased. Irrigation twice throughout the whole growth season induced a higher NUE and higher dry matter accumulation in spike, as compared to irrigation once. The irrigation amount at wintering time and the total irrigation amount had lesser effects on the tillering and the dry matter accumulation in spike. Increasing irrigation amount at jointing stage or booting stage more benefited the nutrient uptake, dry matter accumulation and translocation, and grain WUE, which in turn made the yield-formation factors be more balance and the grain yield be higher. It was concluded that to guarantee the irrigation amount at wintering time could achieve stabilized yield, and the optimal irrigation mode was irrigation at wintering time plus an additional irrigation at jointing stage (900 m³·hm^-2), which could satisfy the water demand of winter wheat at its mid and later growth stage and increase the WUE of grain, and realize water-saving and high-yielding cultivation.

Effects of different irrigation modes on winter wheat grain yield and water- and nitrogen use efficiency. 

2011, 22(10):  2517-2523. 

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Taking the widely planted winter wheat cultivar Tainong 18 as test material, a field experiment was conducted to study the effects of different irrigation modes on the winter wheat grain yield and water- and nitrogen use efficiency in drier year (2009-2010) in Tai’an City of Shandong Province, China. Five treatments were installed, i.e., irrigation before sowing (CK), irrigation before sowing and at jointing stage (W₁), irrigation before sowing and at jointing stages and at over-wintering stage with alternative irrigation at milking stage (W₂), irrigation before sowing and at jointing and flowering stages (optimized traditional irrigation mode, W₃), and irrigation before sowing and at over-wintering, jointing, and milking stages (traditional irrigation mode, W₄). The irrigation amount was 600 m³·hm^-2 one time. Under the condition of 119.7 mm precipitation in the winter wheat growth season, no significant difference was observed in the grain yield between treatments W₂ and W₄, but the water use efficiency was significantly higher in W₂ than in W₄. Comparing with treatment W₃, treatments W₂ and W₄ had obviously higher grain yield, but the water use efficiency had no significant difference. The partial factor productivity from N fertilization was the highest in W₂ and W₄, and the NO₃^--N accumulation amount in 0-100 cm soil layer at harvest was significantly higher in W₂ than in W₃ and W₄, suggesting that W₂ could reduce NO₃^--N leaching loss. Under the conditions of our experiment, irrigation before sowing and jointing stages  and at over-wintering stage with alternative irrigation at milking stage was the optimal irrigation mode in considering both the grain yield and the water- and nitrogen use efficiency.

Effects of rotational tillage during summer fallow on wheat field soil water regime and grain yield. 

2011, 22(10):  2524-2532. 

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In 2007-2010, a field experiment was conducted to study the effects of different rotational tillage practices during summer follow on the soil water regime and grain yield in a winter wheat field in Southern Ningxia arid area. Three treatments were installed, i.e., T₁(no-tillage in first year, subsoiling in second year, and no-tillage in third year), T₂(subsoiling in first year, no-tillage in second year, and subsoiling in third year), and CT (conventional tillage in the 3 years). Through the three years of the tillage practices, the soil water storage efficiency in treatments T₁ and T₂ was increased averagely by 15.2% and 26.5%, respectively, as compared to CT. In treatments T₁ and T₂, the potential rainfall use rate was higher, being 37.8% and 38.5%, respectively, and the rainfall use efficiency was increased averagely by 9.9% and 10.7%, respectively, as compared to CT. Rotational tillage during summer fallow could decrease the soil ineffective evaporation significantly, and save the soil water effectively in wheat growth season. At early growth stage, the water storage in 0-200 cm soil layer in treatments T₁ and T₂ was increased averagely by 6.8% and 9.4%, as compared to CT; at jointing, heading, and filling stages, the water storage in 0-200 cm soil layer in treatments T₁ and T₂ had a significant increase, giving greater contribution to the wheat yield than the control.Different rotational tillage practices increased the water consumption by wheat, but in the meantime, increased the grain yield and water use efficiency. In treatments T₁and T₂, the water consumption by wheat through the three years was increased averagely by 5.2% and 6.1%, whereas the grain yield and the water use efficiency were increased averagely by 9.9% and 10.6%, and by 4.5% and 4.3%, respectively, as compared to CT. Correlation analysis showed that in Southern Ningxia arid area, the soil water storage at sowing, jointing, heading, and filling stages, especially at heading stage, could have significant effects on the winter wheat grain yield.

Contribution of wheat rhizosphere respiration to soil respiration under elevated atmospheric CO₂ and nitrogen application.

2011, 22(10):  2533-2538. 

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With the support of free-air carbon dioxide enrichment (FACE) system and by using isotope ¹³C technique, and through planting wheat (Triticum aestivum L., C₃ crop) on a soil having been planted with maize (Zea mays L., C₄ crop) for many years, this paper studied the effects of elevated atmospheric CO₂ and nitrogen application on the δ¹³C value of soil emitted CO₂ and the wheat rhizosphere respiration. With the growth of wheat, the δ¹³C value of soil emitted CO₂ had a gradual decrease. Elevated atmospheric CO₂ concentration (200 μmol·mol^-1) decreased the δ¹³C value of emitted CO₂ at booting and heading stages significantly when the nitrogen application rate was 250 kg·hm^-2 (HN), and at jointing and booting stages significantly when the nitrogen application rate was 150 kg·hm^-2 (LN). Nevertheless, the elevated atmospheric CO₂ promoted the proportions of wheat rhizosphere respiration to soil respiration at booting and heading stages significantly. From jointing stage to maturing stage, the proportions of wheat rhizosphere respiration to soil respiration were 24%-48% (HN) and 21%-48% (LN) under elevated atmospheric CO₂, and 20%-36% (HN) and 19%-32% (LN) under ambient atmospheric CO₂. Under both elevated and ambient atmospheric CO₂ concentrations, the δ¹³C value of emitted CO₂ and the rhizosphere respiration had different responses to the increased nitrogen application rate, and there was a significant interactive effect of atmospheric CO₂ concentration and nitrogen application rate on the wheat rhizosphere respiration at jointing stage.

Effects of seed soaking with humic acid on wheat seedlings antioxidant system under salt-alkali stress.

2011, 22(10):  2539-2545. 

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The seeds of two spring wheat genotypes Longmai 26 and Kehan 16 were soaked with humic acid to study the effects of seed soaking with humic acid on the seedlings antioxidant system of the two genotypes under NaCl and Na₂CO₃ stresses. Under the salt and alkali stresses, the seedlings leaf proline (Pro) content increased, membrane permeability enhanced, and aboveground fresh mass decreased. Under NaCl stress, the leaf catalase (CAT) activity increased, peroxidase (POD) activity decreased, and superoxide dismutase (SOD) decreased after an initial increase; under Na₂CO₃ stress, the CAT and POD activities increased while the SOD activity was in adverse. The activities of the test antioxidant enzymes were higher under Na₂CO₃ than under NaCl stress. When the seeds were soaked with humic acid, the seedlings leaf glutathione (GSH) content increased, and the SOD and CAT activities improved, which effectively relieved the damage of salt-alkali stress on the seedlings growth. Some differences were observed in the resistance level and related mechanisms against the salt-alkali stress between the two wheat genotypes, possibly due to their different interactions with the salt ion components and concentrations and the ways of seed soaking.

Seasonal dynamics of carbon and nitrogen concentrations in Phellodendron amurense fine roots.

2011, 22(10):  2546-2552. 

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Taking a 23 years old Phellodendron amurense plantation as test object, the first five order roots of P. amurense were sampled to study the seasonal dynamics of their total carbon (TC), total nitrogen (TN), total non-structural carbohydrates (TNC), and soluble N concentrations, with the correlations among these parameters analyzed. In the first five order roots, the TNC occupied 49% of TC, and the soluble N accounted for 26% of TN. Within the growth season, the rate of TNC to TC increased from 42% in the first order roots to 52% in the fifth order roots, and the rate of soluble N to TN decreased from 28% to 21% correspondingly. All the first five order roots had the lowest concentration of TC but the highest concentration of TN in spring, and the lowest concentrations of TNC and soluble N in summer. The increase of the TC concentration in the roots decreased the concentrations of TNC and soluble N, whereas the increase of the TN concentration decreased the TNC concentration significantly and increased the concentration of soluble N. From the first to the fifth order roots, the TC and TN had an increasing correlation with TNC but a decreasing correlation with soluble N, suggesting the close correlations of TNC and soluble N with TC and TN in P. amurense fine roots.

Effects of snow pack removal on the dynamics of winter-time soil temperature, carbon, nitrogen, and phosphorus in alpine forests of west Sichuan.

谭波,吴福忠,杨万勤,杨玉莲,王奥,康丽娜

2011, 22(10):  2553-2559. 

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The dynamic changes of snow pack as affected by global warming might have strong effects on the ecological processes in alpine forests. To understand the responses of soil ecological processes in the alpine forests of west Sichuan to the decreasing snow pack under global warming, a snow-shading experiment was conducted in a primary fir forest from October 19, 2009 to May 18, 2010, with the effects of snow pack removal on the dynamics of soil temperature, carbon, nitrogen, and phosphorus investigated. The results showed that snow pack removal increased the diurnal variation amplitude of soil temperature and the frequency of freeze-thaw cycle, and advanced the time of soil frozen and melt as well as the peak time of soil dissolved carbon and nitrogen, available P, NH₄⁺-N, and NO₃^--N. Snow pack removal increased the concentrations of soil dissolved carbon and nitrogen and NO₃^--N but decreased the concentrations of soil available P and NH₄⁺-N, and changed the ratios of soil dissolved carbon and nitrogen, available P, NH₄⁺-N, and NO₃^--N in the period of snow cover and snow melt. The decreased snow pack in winter time in the alpine forests of west Sichuan as affected by global warming could alter the soil exterior environment, and further, affect the processes of soil carbon, nitrogen and phosphorus.

Short-term effects of understory vegetation removal on nutrient cycling in litter layer of Chinese fir plantation. 

2011, 22(10):  2560-2566. 

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A short-term understory vegetation removal experiment was conducted at three experimental sites of Chinese fir (Cunninghamia lanceolata) plantation in Huitong of Hunan Province, South-central China to examine the short-term effects of the absence of understory vegetation on litter decomposition. In the plantation, the standing stock of the litter in L layer (un-decomposed litter), F layer (semi-decomposed litter), and H layer (decomposed litter) under understory intact condition was (123.7±46.3) g·m^-2, (204.2±79.1) g·m^-2, and (187.1±94.8) g·m^-2, and the corresponding nutrient storage was (447.51±16.75) g·kg^-1, (418.89±35.75) g·kg^-1, and (376.11±47.33) g·kg^-1 for carbon, (4.87±1.24) g·kg^-1, (6.4±2.38) g·kg^-1, and (4.66±2.64) g·kg^-1 for nitrogen, and (0.14±0.01) g·kg^-1, (0.16±0.03) g·kg^-1, and (0.16±0.02) g·kg^-1 for phosphorus, respectively. At sites DL87 and MS90, understory vegetation removal had significant effects on the standing stock of litter and the corresp onding storage of carbon, nitrogen, and phosphorus in F layer, though the effects varied with sites (e.g., the storage of litter carbon, nitrogen, and phosphorus decreased by more than 55% at DL87 while increased by about 1 time at MS90). Across the three sites, understory vegetation removal had little effects on the standing stock and nutrient storage of the litter in L layer and H layer. In addition, the removal had little effects on the litter decomposition at its early stage, but showed significant inhibitory effects after 150 days elapsed, with the decomposition rate decreased by 20.8%. These results suggested that the short-term effects of understory vegetation removal on the litter nutrient cycling could be depended on the forest site condition and the duration after the understory vegetation removal.

Effects of forest type on soil organic matter, microbial biomass, and enzyme activities.

2011, 22(10):  2567-2573. 

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Taking the typical forest types Pinus elliottii  var. elliotttii, Araucaria cunninghamii, and Agathis australis in southern Queensland of Australia as test objects, an investigation was made on the soil soluble organic carbon (SOC) and nitrogen (SON), microbial biomass C (MBC) and N (MBN), and enzyme activities, aimed to understand the effects of forest type on soil quality. In the three forests, soil SOC content was 552-1154 mg·kg^-1, soil SON content was 20.11-57.32 mg·kg^-1, soil MBC was 42-149 mg·kg^-1, soil MBN was 7-35 mg·kg^-1, soil chitinase (CAS) activity was 2.96-7.63 μg·g^-1·h^-1, soil leucine aminopeptidase (LAP) activity was 0.18-0.46μg·g^-1·d^-1, soil acid phosphatase (ACP) activity was 16.5-29.6 μg·g^-1·h^-1, soil alkaline phosphatase (AKP) activity was 0.79-3.42 μg·g^-1·h^-1, and soil β-glucosidase (BG) activity was 3.71-9.93 μg·g^-1·h^-1. There was a significant correlation between soil MBC and MBN. Soil SOC content and soil CAS and LAP activities decreased in the order of P. elliottii > A. cunninghamii > A. australis, soil SON content decreased in the order of A. cunninghamii > A. australis > P. elliottii and was significantly higher in A. cunninghamii than in P. elliottii forest (P<0.05), soil MBC and MBN and AKP activity decreased in the order of A. australis > P. elliottii > A. cunninghamii, and soil ACP and BG activities decreased in the order of P. elliottii > A. australis> A. cunninghamii. Among the test soil biochemical factors, soil MBC, MBN, SON, and LAP had greater effects on the soil quality under the test forest types.

Species composition and point pattern analysis of standing trees in secondary Betula albo-sinensis forest in Xiaolongshan of west Qinling Mountains.

2011, 22(10):  2574-2580. 

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An investigation was conducted on the species composition and population diameter-class structure of a typical secondary Betula albo-sinensis forest in Xiaolongshan of west Qinling Mountains, and the spatial distribution pattern and interspecific correlations of the main populations were analyzed at multiple scales by the O-ring functions of single variable and double variables. In the test forest, B. albo-sinensis was obviously dominant, but from the analysis of DBH class distribution, the B. albo-sinensis seedlings were short of, and the natural regeneration was very poor. On the contrary, the regeneration of Abies fargesii and Populus davidianas was fine. B. albo-sinensis and Salix matsudana had a random distribution at almost all scales, while A. fargesii and P. davidianas were significantly clumped at small scale. B. albo-sinensis had positive correlations with A. fargesii and P. davidianas at medium scale, whereas S. matsudana had negative correlations with B. albo-sinensis, A. fargesii, and P. davidianas at small scale. No significant correlations were observed between other species. The findings suggested that the spatial distribution patterns of the tree species depended on their biological characteristics at small scale, but on the environmental heterogeneity at larger scales. In a period of future time, B. albo-sinensis would still be dominant, but from a long-term view, it was necessary to take some artificial measures to improve the regeneration of B. albo-sinensis.

Carbon sequestration potential of forest vegetation in Jiangxi and Zhejiang provinces based on national forest inventory.

2011, 22(10):  2581-2588. 

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Based on the sixth national forest inventory (1999-2003) and the investigation data of 1030 forest sampling plots in subtropical China collected from publications, and by using stand growth empirical equation, this paper estimated the carbon sequestration potential of forest vegetation under natural growth in Jiangxi and Zhejiang provinces in 2004-2013. In the meanwhile, the effects of three forest management measures, including interplanting, selective thinning, and fertilization, on the future forest carbon sequestration were explored by using the survey data of 455 sampling plots. In 2004-2013, the mean annual carbon sequestration potential of forest vegetation under natural growth in Jiangxi and Zhejiang could reach 11.37 and 4.34 Tg C·a^-1 (1 Tg=10¹²g), respectively. Interplanting could generate the largest carbon sequestration potential of forest vegetation, followed by selective thinning, and fertilization, resulting in an increase in the potential by (6.54±3.9) Tg C·a^-1, (3.81±2.02) Tg C·a^-1,and (2.35±0.6) Tg C·a^-1 in Jiangxi and by (2.64±1.28) Tg C·a^-1, (1.42±0.69) Tg C·a^-1, and (1.15±0.29) Tg C·a^-1 in Zhejiang, respectively.

Water-holding characteristics and accumulation amount of the litters under main forest types in Xinglong Mountain of Gansu, Northwest China.

2011, 22(10):  2589-2598. 

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By the methods of field survey and laboratory soaking extraction, an investigation was conducted on the accumulation amount, water-holding capacity, water-holding rate, and water-absorption rate of the litters under six main forests (Picea wilsonii forest,P. wilsonii -  Betula platyphlla forest, Populus davidiana - B. platyphlla forest, Cotonester multiglorus - Rosa xanthina shrubs, Pinus tabulaeformis forest, and Larix principis-rupprechtii forest) in Xinglong Mountain of Gansu. The accumulation amount of the litters under the forests was 13.40-46.32 t·hm^-2, and in the order of P. tabulaeformis forest > P. wilsonii - B. platyphlla  forest ＞L. principis-rupprechtii forest ＞ P. wilsonii forest ＞C. multiglorus-R. xanthina shrubs ＞P. davidiana -B. platyphlla  forest. The litter storage of coniferous forests was greater than that of broadleaved forests, and the storage percentage of semi-decomposed litters was all higher than that of un-decomposed litters. The maximum water-holding rate of the litters was 185.5%-303.6%, being the highest for L. principis-rupprechtii forest and the lowest for P. tabulaeformis forest. The litters’ water-holding capacity changed logarithmically with their soaking time. For coniferous forests, un-decomposed litters had a lower water-holding rate than semi-decomposed litters; whereas for broadleaved forests, it was in adverse. The maximum water-holding capacity of the litters varied from 3.94 mm to 8.59 mm, and was in the order of P. tabulaeformis forest ＞L. principis-rupprechtii forest ＞P. wilsonii - B. platyphlla  forest ＞P. wilsonii forest ＞C. multiglorus - R. xanthina shrubs ＞P. davidiana - B. platyphlla  forest. The litters’ water-holding capacity also changed logarithmically with immersing time, and the half-decomposed litters had a larger water-holding capacity than un-decomposed litters. The water-absorption rate of the litters presented a power function with immersing time. Within the first one hour of immersed in water, the water-absorption rate of the litters declined linearly; after the first one hour, the litters’ water-absorption rate became smaller, and changed slowly at different immersed stages. Semi-decomposed litters had a higher water-absorption rate than un-decomposed litters. The effective retaining amount (depth) of the litters was in the order of P. wilsonii -B. platyphlla  forest (5.97 mm)＞P. tabulaeformis forest (5.59 mm) ＞L. principis-rupprechtii forest (5.46 mm)＞P. wilsonii forest (4.30 mm) ＞C. multiglorus - R. xanthina shrubs (3.03 mm)＞P. davidiana - B. platyphlla  forest (2.13 mm).

Photosystem  Ⅱ characteristics of nine Gramineae  species in southern Taklamakan Desert.

2011, 22(10):  2599-2603. 

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Taking the Gramineae species Elytrigia intermedia, Avena sativa, Bromus inermis, Elymus sibiricus, Leymus tianschanicus, Elymus dahuricus, Festuca elata, Agropyron cristatum, and Puccinellia distans at the edge of Cele Oasis in southern Taklimakan Desert as test objects, this paper monitored their fast chlorophyll fluorescence kinetics after 20 minutes adaptation in darkness, compared their photosystem Ⅱ (PSⅡ) characteristics, and analyzed their adaptability to the local environment. Among the nine Gramineae species, L. tianschanicus and E. dahuricus had markedly higher values of maximum fluorescence yield (F_m), maximum photochemical efficiency of PSⅡ (F_v/F_m), and active reaction centers per cross-section (RC/CS_o), but lower values of minimum fluorescence yield (F_o), absorption flux per reaction center (ABC/RC), maximal trapping flux per reaction center (TR_o/RC), flux of dissipated excitation energy per reaction center (DI_o/RC), and initial slope of fluorescence intensity (M_o), as compared to F. elata, A. cristatum, and P. distans, whereas E. intermedia, A. sativa, B. inermis, and E. sibiricus had a medium level of the values. These results suggested that all the test pasture species were suffered from the severe environmental conditions of Cele Oasis to some extent, as indicated by the inactivation of PSⅡ reaction center and the depression of electron transport chain. L. tianschanicus and E. dahuricus were least impacted, while F. elata, A. cristatum, and P. distans were most impacted.

Effects of loess soil stabilization on Lolium perenne L. growth and root activity.

2011, 22(10):  2604-2608. 

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Taking the loess soils with bulk density 1.2 g·cm^-3, 1.3 g·cm^-3, and 1.4 g·cm^-3 from Ansai, Shaanxi Province as test objects, a pot experiment was conducted to study the effects of different amendment amount of soil stabilizer (EN-1 stabilizer) on the growth and root activity of ryegrass (Lolium perenne L.). Within the range of the bulk densities, the leaf chlorophyll content, root activity, root/shoot ratio, root biomass, and plant biomass of L. perenne all decreased with increasing soil bulk density, and were higher under the amendment of EN-1 stabilizer, as compared with the control. With increasing amendment amount of EN-1 stabilizer, the leaf chlorophyll content, root activity, root/shoot ratio, root biomass, and plant biomass had a trend of increased first and decreased then. Soil bulk density and stabilizer amendment amount had significant interactive effect on the root biomass and plant biomass. Overall, the values of the test indices were the highest under 1.3 g·cm^-3 soil bulk density and 0.15% EN-1 stabilizer amendment amount.

Effects of whole field-surface plastic mulching and planting in furrow on soil temperature, soil moisture, and corn yield in arid area of Gansu Province, Northwest China. 

2011, 22(10):  2609-2614. 

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Taking spring corn (Zea mays) cultivar Shendan 16 as test material, a field experiment was conducted to study the effects of the treatments whole-field surface plastic mulching and planting in furrow (PMF), whole-field surface sand mulching and flat planting (SM), and uncovered and flat planting (CK) on the soil temperature, soil moisture, and corn yield on the dry land of arid area (annual average precipitation 415 mm) in middle Gansu Province. Comparing with CK, treatments PMF and SM increased the average temperature in 0-25 cm soil layer before tasselling stage, with the highest increment in treatment PMF. As for the soil water consumption, its depth in the three treatments increased with increasing years of planting. In the first year of planting, the soil water consumption was the most in 20-120 cm soil layer; whereas in the second year, the consumption was the most in 120-200 cm soil layer, with the soil water loss being the highest in treatment PMF. Treatment PMF had the highest grain number, grain weight per spike, and 100-grain weight, followed by treatment SM, and CK. In 2009 and 2010, the average grain number, average grain weight per spike, and average 100-grain weight in treatment PMF were increased by 13.5% and 114.2%, 29.8% and 321.1%, and 14.4% and 95.4% respectively, as compared to treatments SM and CK, and the grain yield and water use efficiency in treatments PMF and SM were increased by 333.1% and 240.2%, and 290.6% and 227.6%, respectively, as compared to CK. After two years continuous cropping of corn, the soil water loss in 120-200 cm soil layer in treatment PMF was up to 72 mm, being significantly higher than that in treatments SM (45 mm) and CK (40 mm). It was suggested that PMF could increase the soil temperature at seedling-tasselling stage, promote the corn growth in its early growth period, improve the soil water use by corn, and consequently, increase the grain number per spike and 100-grain weight, manifesting a good effect in improving corn yield and water use efficiency. However, PMF also induced more soil water consumption in 100-200 cm soil layer, which was not beneficial to the water balance through years.

Effects of different nitrogen, phosphorous, and potassium fertilization modes on carbon- and nitrogen accumulation and allocation in rice plant.

2011, 22(10):  2615-2621. 

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Based on a 20-year field site-specific fertilization experiment in Taoyuan Experimental Station of Agriculture Ecosystems under Chinese Ecosystem Research Network (CERN), this paper studied the effects of different fertilization modes of N, P, and K on the accumulation and allocation of C and N in rice plant. The fertilization mode N-only showed the highest C and N contents (433 g·kg^-1 and 18.9 g·kg^-1, respectively) in rice grain, whereas the modes balanced fertilization of chemical N, P and K (NPK) and its combination with organic mature recycling (NPKC) showed the highest storage of C and N in rice plant. In treatments NPK and NPKC, the C storage in rice grain and in stem and leaf was 1960 kg·hm^-2 and 2015 kg·hm^-2, and 2002 kg·hm^-2and 2048 kg·hm^-2, and the N storage in rice grain was 80.5 kg·hm^-2 and 80.6 kg·hm^-2, respectively. Treatment NPK had the highest N storage (59.3 kg·hm^-2)in stem and leaf. Balanced fertilization of chemical N, P, and K combined with organic manure recycling increased the accumulation of C and N in rice plant significantly. Comparing with applying N only, balanced fertilization of chemical N, P, and K was more favorable to the accumulation and allocation of C and N in rice plant during its growth period.

Nutrient balance between N, P, and K in flue-cured tobacco production under different preceding crops planting.

2011, 22(10):  2622-2626. 

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A field experiment was conducted to study the nutrient balance between N, P, and K in flue-cured tobacco production in Shilin County of Yunnan Province under the effects of different preceding crops including rape, wheat, barley, and green manure planting. Overall, there existed significant differences in the soil nitrogen availability, tobacco plant dry matter accumulation, plant uptake of N, P and K, residual amounts of soil N, P, and K, apparent soil N loss, and apparent soil P- and K surplus during tobacco growth period under different preceding crops planting. Under preceding crop green mature planting, the soil mineral N content before tobacco plant transplanting, the soil N net mineralization rate during tobacco growth period,and the tobacco plant dry matter accumulation and N- and K uptake at maturation were all the highest, followed by under preceding rape planting, and under preceding barley or wheat planting. The P uptake by tobacco plant was also obviously higher under the preceding green manure or rape planting than under preceding barley or wheat planting. After the harvest of tobacco leaves, the soil residual mineral N content was the highest under the preceding green manure planting, followed by under preceding rape planting, and by preceding barley or wheat planting, while the soil available P and K contents were in adverse, being the highest under preceding barley or wheat planting and the lowest under preceding green manure planting. The apparent soil N loss during tobacco growth period was the highest under the preceding green manure planting, whereas the apparent soil P- and K surplus was obviously higher under preceding wheat or barley planting. It was suggested that an appropriate adjustment should be made on the fertilization rates of N, P, and K for tobacco production based on the preceding crops, i.e., lesser N application when the preceding crop was green manure or rape, and lesser application of P and K when the preceding crop was wheat or barley.

Effects of intercropping Chinese onion cultivars of different allelopathic potential on cucumber growth and soil micro-environment.

2011, 22(10):  2627-2634. 

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A pot experiment was conducted to study the effects of intercropping various Chinese onion cultivars of different allelopathic potential on the cucumber growth and rhizospheric soil  environment. When intercropped with high allelopathic Chinese onion cultivars, the EC value and peroxidase activity of cucumber rhizospheric soil decreased, while the pH value, invertase and catalase activities, and bacterial community diversity increased. The cloning and sequencing results indicated that most DGGE bands amplified from cucumber rhizospheric soil samples showed a high homology to uncultured bacterial species. The common bands were affiliated with Actinobacteria and Proteobacteria, and the differential bacteria bands were affiliated with Proteobacteria and Anaerolineaceae. Rhodospirillales and Acidobacteria were only found in the cucumber rhizospheric soil intercropped with low allelopathic Chinese onion cultivars. Correlation analysis showed that there were significant positive correlations between rhizospheric soil urease activity and cucumber seedlings height, total dry biomass, leaf area, and DGGE band number. It was suggested that intercropping high allelopathic Chinese onion cultivars could establish a good rhizospheric soil micro-environment for cucumber growth, and promote the growth of cucumber seedlings markedly.

Effects of climate warming on oil flax growth and water use efficiency in semi-arid region of Loess Plateau, Northwest China. 

2011, 22(10):  2635-2642. 

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By using the site-specific observation data of oil flax growth and related meteorological records in semi-arid region of Loess Plateau, this paper studied the effects of climate change on the oil flax growth, and analyzed the relationships between the oil flax water use efficiency and meteorological condition. In this region, the annual precipitation displayed a decreasing trend, and its climatic trend rate was -15.80 mm·(10 a)^-1, with an annual periodic change of 3 a and 6 a, whereas the annual air temperature had an increasing trend, and its climatic trend rate was 0.36 ℃·(10 a)^-1. In crop growth period, the aridity index displayed a marked increasing trend, its climatic trend rate was 0.12·(10 a)^-1, and the aridity tendency was more obvious from the beginning of 1990s to the year 2009. From sowing to maturation, oil flax needed 120-150 d, 1700-2100 ℃·d of ≥0 ℃ accumulated temperature, 200-250 mm precipitation, and 1000-1300 h sunshine hours. The main meteorological factors affecting the oil flax growth in the region were air temperature and precipitation. The increase of air temperature shortened the prophase vegetative growth stage, whereas the increase of air temperature and the decrease of precipitation extended the reproductive growth stage, causing the extension of the whole growth period of the oil flax. The air temperature in the oil flax whole growth period except at seeding stage and maturing stage had negative effect on the yield formation, being more obvious at squaring stage, whereas the precipitation in the whole growth period except at blooming stage had positive effect on the yield formation, being more obvious at seeding stage. The water use efficiency of the oil flax was significantly positively correlated with the air temperature and sunshine hours at seeding stage as well as the aridity index from squaring stage to maturing stage, and negatively correlated with the precipitation from squaring stage to maturing stage. In the study region, the aridity index from May to July was the key factor affecting the water use efficiency of oil flax.

Responses of Pinus koraiensis tree ring cell scale parameters to climate elements in Changbai Mountains.

2011, 22(10):  2643-2652. 

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Based on the tree ring samples of Pinus koraiensis collected from the low altitude areas of Changbai Mountains, seven standard chronologies for tree ring width and cell scale parameters were constructed. Parts of the chronologies were chosen for the correlation analysis with the climate elements in 1959-2007 at Donggang meteorological station, and the changes of the correlations between tree ring indices and climate elements before and after 1988 in which the climate changed abruptly were discussed. In the seven standard chronologies constructed, cell number had the best correlation with tree ring width. Both precipitation and air temperature were the limiting factors for the growth of P. koraiensis, but the chronologies had better correlation with precipitation than with air temperature, mainly manifested in the significant correlation between the chronologies and the precipitation in previous September and current May and June. Comparing with tree ring width, cell size could reveal more climatic information, mainly manifested in the positive correlation between the chronologies and the air temperature in March and the precipitation in May, and the negative correlation between the chronologies and the air temperature in May. After the abrupt change of air temperature in 1988, the responses of cell size to climate elements had some changes, mainly manifested in the decreasing sensitivity to monthly climate elements and the earlier response time.

Compatible biomass models for main tree species with measurement error in Heilongjiang Province of Northeast China.

2011, 22(10):  2653-2661. 

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Based on the biomass data of 516 sampling trees, and by using non-linear error-in-variable modeling approach, the compatible models for the total biomass and the biomass of six components including aboveground part, underground part, stem, crown, branch, and foliage of 15 major tree species (or groups) in Heilongjiang Province were established, and the best models for the total biomass and components biomass were selected. The compatible models based on total biomass were developed by adopting the method of joint control different level ratio function. The heteroscedasticity of the models for total biomass was eliminated with log transformation, and the weighted regression was applied to the models for each individual component. Among the compatible biomass models established for the 15 major species (or groups), the model for total biomass had the highest prediction precision (90% or more), followed by the models for aboveground part and stem biomass, with a precision of 87.5% or more. The prediction precision of the biomass models for other components was relatively low, but it was still greater than 80% for most test tree species. The modeling efficiency (EF) values of the total, aboveground part, and stem biomass models for all the tree species (or groups) were over 0.9, and the EF values of the underground part, crown, branch, and foliage biomass models were over 0.8.

Assessment and spatiotemporal difference of ecosystem services value in Shaanxi Province.

2011, 22(10):  2662-2672. 

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Based on the investigation data of land use change and the services values of terrestrial ecosystems in China, this paper analyzed the variations of ecosystem services values and their differences at different scales in Shaanxi Province, and approached the effects of the requisition-compensation balance of cultivated land and the program of conversing cropland into forestland on the ecosystem services values as well as their dynamic variations in the Province from 2001 to 2006. In the study period, the total ecosystem services value in the Province had an overall increasing trend. The ecosystem services value of forestland accounted for more than 76.5%, and its increment occupied 97.5% of the total; whereas the ecosystem services values of arable land, grassland, and unused land decreased, and the decrement of the ecosystem services value of cultivated land accounted for 81.7% of the total. The services values of urban ecosystems in the Province in 2001-2006 all increased to some extent, with the largest increment in Yan’an City, followed by in Yulin City, and the smallest in Yangling District. The ecosystem services value in the Loess Plateau increased most obviously, with the increment accounted for 61.2% of the total, followed by in the Qinba Mountains, and the least in the Guanzhong Plain. The requisition-compensation balance of cultivated land in the Province did well, with the ecosystem services value presented an increasing trend. The program of conversing cropland into forestland increased the ecosystem services value most in the Loess Plateau whereas the least in the Guanzhong Plain．

Coordinated evolvement of dynamic coupling between economic and environmental systems in Shenyang Metropolitan Area. 

2011, 22(10):  2673-2680. 

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By using coupling coordinated degree model, scissors difference methods, and coupling degree model, this paper analyzed the coupling coordinated status, development speed difference, and coupling development trend between economic and environmental systems in Shenyang Metropolitan Area in 1990-2009. In the study period, the coupling level of the relations between economic and environmental development was ascending, with the coupling degree increased from 0.42 to 0.89, which reflected the more and more harmonious relationships between economy and environment. The decrease of economic development speed and the increase of environmental construction speed reduced the scissor difference of the two systems from 0.63° to 0.22°, demonstrating the contribution of the economic development speed to the coupling coordinated status. The coupling degree between the economic and environmental systems stretched across in a \[45°, 90°\] region, which meant that the two systems were in a co-developing status. As the discrepancy between the development speeds of the two systems became smaller, the coupling degree was closer to 45°, and the two systems were becoming better coordinated.

Land ecological safety in Poyang Lake Eco-economic Zone: An evaluation based on matter-element model.

2011, 22(10):  2681-2685. 

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Base on the 2001-2007 related statistical data, and by means of matter-element model, an evaluation was conducted on the land ecological safety in Poyang Lake Eco-economic Zone. The land safety in the Eco-economic Zone was relatively fine in 2001, decreased to critical level in 2002-2004, and degraded to unsafe in 2005. From 2006, the safety level returned to critical, indicating a better safety status. This study showed that matter-element model had the advantages of simple calculation, clear indication, and higher accuracy, being able to provide another approach for regional land ecological safety evaluation.

Livelihood status assessment of farmers and herdsmen’s households based on participatory appraisal: A case in Taipusi Banner of Inner Mongolia. 

2011, 22(10):  2686-2692. 

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Participatory appraisal method was adopted to investigate the recent livelihood status of different type farmers and herdsmen’s households in the Taipusi Banner of Inner Mongolia agriculture- animal husbandry ecotone, aimed to understand their livelihood strategies and restricting factors and to search for the ways to improve their living standards. The households dealing with pure agricultural production had smaller family size, with older age-structure and lower educational level, and their simple livelihood strategies brought about larger vulnerability and risk. To introduce and expand non-agricultural activities would be the important way to promote the livelihood diversification and to reduce the livelihood risks of these households. The households dealing with pure animal husbandry took grazing as the main subsistence, and their production activities were greatly restrained by the pasture vulnerability. To develop environment-friendly and high-yielding agriculture and animal husbandry would be the effective way to solve the livelihood problems of these households and to protect the ecological environment. The households dealing with both agricultural production and business or dealing with both animal husbandry and business generally had larger family size, with younger age- structure, higher diversity in labor division, larger proportion of non-farming activities, and better living standards. Especially for the households dealing with both animal husbandry and business, their income was much higher.

Effects of planting rubber and crops on the keeping number of livestock and poultry in the Naban River Watershed National Nature Reserve.

2011, 22(10):  2693-2698. 

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A total of 207 householders from 13 natural villages in the Naban River Watershed National Nature Reserve were chosen for a systematic survey on the farming and livestock husbandry, aimed to evaluate the effects of planting rubber and crops on the keeping number of livestock and poultry in the study area. The livestock and poultry bred in the Reserve were mainly buffalo, Yunnan Yellow cattle, small-eared pig,  Chahua chicken, and a few Banna game fowls. Exotic breeds were very limited. From 1991 to 2008, the planting area of rubber increased year by year, giving negative effects on the corn, rice, and cash crop production as well as the keeping number of livestock and poultry. Planting rubber had significant negative effects on the keeping number of buffalo and small-eared pig. The families planting rubber kept significantly less buffalo and small-eared pig, as compared to those not planting rubber. The planting areas of corn, rice, and cash crops had positive effects on the keeping number of buffalo, Yunnan Yellow cattle, and small-eared pig, and the total planting area of the crops had active effects on the keeping number of buffalo and Chahua chicken. The development of rubber production led to an obvious change in land use pattern, which in turn had significant effects on the keeping number of livestock and poultry. With the increasing rubber planting area year by year, the local livestock husbandry would be restrained.

Basidiomycetous laccase gene diversity in two subtropical forest soils.

2011, 22(10):  2699-2704. 

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As one of the key enzymes involved in lignin decomposition of forest litter, laccase plays an important role in the carbon cycling in forest ecosystem. By using TA cloning and sequencing, a comparative study was conducted on the basidiomycetous laccase gene diversity  in the O horizon (litter layer) and A horizon (surface soil layer, 0-20 cm) in two subtropical forests (a primeval evergreen deciduous broadleaved mixed forest and an artificial masson pine forest). For the same soil horizons, the basidiomycetous laccase gene diversity and richness were higher in the primeval forest than in the masson pine forest; for the same forest ecosystems, the basidiomycetous laccase gene diversity and richness in the primeval forest were slightly higher in O horizon than in A horizon, but those in the masson pine forest were apparently lower in O horizon than in A horizon. The two forest soils had the same dominant laccase gene-containing basidiomycetous populations, and most of the populations had high similarity of amino acid sequence to Mycena sp. or Pleurotus sp. belonging to Agaricales. Comparing with the A horizon in primeval forest and the O horizon in masson pine forest, the O horizon in primeval forest and the A horizon in masson pine forest had a relatively uniform distribution of basidiomycetous populations. The nucleotide sequence similarity of basidiomycetous laccase gene between the O and A horizons in the masson pine forest was higher than that in the primeval forest. This study showed that vegetation and soil horizon had significant effects on the basidiomycetous laccase gene diversity and community structure, and the discrepancies in the substrate availability for basidiomycetes and in the soil pH induced by the vegetation and soil horizon could be the driving forces.

Phylogenetic diversity of dissimilatory Fe(III)-reducing bacteria in paddy soil. 

2011, 22(10):  2705-2710. 

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Microorganism-mediated dissimilatory Fe(III) reduction is recognized as the dominant mechanism for Fe(III) reduction to Fe(II) in non-sulfidogenic anaerobic environments, but the microorganisms involved, especially in paddy soil, are still poorly understood. In this paper, an enrichment culture was conducted to study the phylogenetic diversity of Fe(III)-reducing bacteria in paddy soil, with acetate or hydrogen as the electron donor and with ferrihydrite or goethite as the electron acceptor, and by the methods of terminal-restriction fragment length polymorphism (T-RFLP) technology and 16S rRNA genes cloning and sequencing. No matter what the electron donor and electron acceptor were supplemented, the most abundant microorganisms were Geobacter and Clostridiales, and Rhodocyclaceae were also abundant, when acetate was supplemented as electron donor, which suggested that besides Geobacter, Clostridiales and Rhodocyclaceae could be also the important Fe(III)-reducing bacteria in paddy soil.

Polypore species diversity, floral composition, and distribution characteristics in Changbai Mountains, Northeast China.

2011, 22(10):  2711-2717. 

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Polypore is an important group of wood-rotting fungi, which can decompose wood cellulose, semi-cellulose, and lignin into nutrients to be utilized by itself and other organisms, and accordingly, can promote the material cycling in forest ecosystem. Based on more than 10 years investigation and collection, it was found that the polypore in Changbai Mountains was rich in species diversity, with the Shannon diversity index being 5.06. In the Mountains, a total of 246 polypore species were recorded, occupying 40.7% of the total in China. The polypore species recorded belonged to 80 genera, 11 families, and 6 orders, among which, Polyporaceae was the dominant family. The most important bio-geographical elements of the polypore in Changbai Mountains were north temperate element and cosmopolitan element, other elements also included, showing a distinct north temperate character in floral composition. Pinus was the main host of polypore, supporting 41.5% of the polypore in Changbai Mountains. Most of the polypore was saprophytic, and its quantity had a significant correlation with the decaying degree of substrates, implying its important role in the material cycling in forest ecosystem in Changbai Mountains. There were 18 threatened polypore species in the Mountains, accounting for 37.5% of total in China. Besides their important ecological functions, many of the polypore also had higher economic value. On the premise of complete protection on them, these fungal resources should be exploited reasonably.

Effects of ryegrass (Lolium perenne) root exudates dose on pyrene degradation and soil microbes in pyrene-contaminated soil.

2011, 22(10):  2718-2724. 

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By simulating a gradually decreasing concentration of root exudates with the distance away from root surface in rhizosphere, this paper studied the effects of ryegrass (Lolium perenne) root exudates dose on the pyrene degradation and microbial ecological characteristics in a pyrene- contaminated soil. It was observed that with the increasing dose of ryegrass root exudates, the residual amount of soil pyrene changed nonlinearly, i.e., increased after an initial decrease. When the root exudates dose was 32.75 mg·kg^-1 of total organic carbon, the residual pyrene was the minimum, indicating that the root exudates at this dose stimulated pyrene degradation significantly. In the meantime, soil microbial biomass carbon and microbial quotient had an opposite trend, suggesting the close relationship between pyrene degradation and soil microbes. In the test soil, microbial community was dominated by bacteria, and the bacteria had the same variation trend as the pyrene degradation, which indicated that the pyrene was degraded mainly by bacteria, and the effects of root exudates on pyrene degradation were mainly carried out through the effects on bacterial population. There was a similar variation trend between the activity of soil dehydrogenase, a microbial endoenzyme catalyzing the dehydrogenation of organic matter, and the soil microbes, which further demonstrated that the variations of soil microbes and their biochemical characteristics were the ecological mechanisms affecting the pyrene degradation in the pyrene-contaminated soil when the ryegrass root exudates dose increased.

Effects of intercropping Sedum plumbizincicola in wheat growth season under wheat-rice rotation on the crops growth and their heavy metals uptake from different soil types.

2011, 22(10):  2725-2731. 

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A pot experiment with heavy metals- contaminated black soil from Heilongjiang Province, alluvial soil from Henan Province, and paddy soil from Zhejiang Province was conducted to study the effects of intercropping Sedum plumbizincicola in wheat growth season under wheat (Triticum aestivum)-rice (Oryza sativa) rotation on the growth of the crops and their heavy metals uptake, aimed to explore the feasibility of simultaneous grain production and heavy metals- contaminated soil phytoremediation in main food crop production areas of this country. Comparing with monoculture T. aestivum, intercropping S. plumbizincicola increased the soil NaNO₃-extractable Zn and Cd significantly, with the increment of extractable Zn in test paddy soil, alluvial soil, and black soil being 55%, 32% and 110%, and that of extractable Cd in test paddy soil and black soil being 38% and 110%, respectively. The heavy metals concentration in T. aestivum shoots under intercropping S.plumbizincicola was 0.1-0.9 times higher than that under monoculture T. aestivum, but the intercropping had little effects on the rice growth and its heavy metals uptake. Though the Cd concentration in rice grain after S. plumbizincicola planting was still higher than 0.2 mg·kg^-1(the limit of Cd in food standard),it presented a decreasing trend, as compared with that after monoculture T. aestivum. Therefore, intercropping S.plumbizincicola in wheat growth season under wheat-rice rotation could benefit the phytoremediation of heavy metals- contaminated soil, and decrease the food-chain risk of rotated rice.

Community structure and biological integrity of periphyton in Hunhe River water system of Liaoning Province, Northeast China.

2011, 22(10):  2732-2740. 

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Taking the Hunhe River water system in Liaoning Province of Northeast China as a case, this paper investigated the community structure of periphyton and the physical and chemical characteristics of water environment at 62 sampling sites, and, by using the biological integrity index of periphyton (P-IBI) and the habitat environment quality index (QHEI), a health assessment on the aquatic ecosystem of the water system was conducted. There was a great spatial heterogeneity in the periphyton community structure, and the sampling sites could be divided into 4 groups, with significant differences in the community structure, species richness, density, and Shannon diversity index among the groups. Canonical correspondence analysis (CCA) showed that ammonia nitrogen (NH₄⁺-N) and dissolved phosphorus (PO₄^3--P) were the main water environment factors driving the formation of the periphyton community structure in the water system. The health assessment of the water system based on P-IBI and QHEI was basically in consistency, though the assessment of several reaches had large discrepancy. Overall, the Suzi River at the upper reaches of the water system had a better health status, while the upper reaches of Hunhe River and the main stream of Hunhe River at its middle and lower reaches were worse in health.

Abundance and biomass of  meiobenthos in Lingdingyang Bay of Pearl River Estuary.

2011, 22(10):  2741-2748. 

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An investigation was conducted on the meiobenthic abundance and biomass in the Lingdingyang Bay of Pearl River Estuary in July-August 2006 (summer), April 2007 (spring), and October 2007 (autumn). A total of 15 meiobenthic groups were recorded, including Nematoda, Copepoda, Polychaeta, Ostracoda, Kinorhyncha, Amphipoda, Cumacea, Tanaidacea, Gnathostomulida, Nemertea, Gastropoda, Bivalvia, Sipuncula, Echiura, and other unidentified taxa. The average abundance of the meiobenthos in spring, summer, and autumn was 272.1±281.9,165.1±147.1 and 246.4±369.3 ind·10 cm^-2, and Nematoda was the most dominant group in abundance, accounting for 86.8%, 83.5%, and 93.4% of the total, respectively, followed by Polychaeta, and benthic Copepoda. The meiobenthic abundance had an uneven vertical distribution. 54.1% of the meibenthos were in 0-2 cm sediments, 35.2% were in 2-5 cm sediments, and 10.8% were in 5-10cm sediments. 87.4% of nematodes were distributed in 0-5 cm sediments.The average biomass of the meiobenthos in spring, summer, and autumn was 374.6±346.9, 274.1±352.2, and 270.8±396.0 μg·10 cm^-2, and Polychaeta was the most dominant group in biomass, accounting for 30.1%, 46.7% and 46.0%, respectively, followed by Nematoda (25.2%, 20.1%, and 34.0%), and Ostracoda (20.6%, 15.3%, and 14.8%). The horizontal distribution of the meiobenthos had a trend of increasing from north to south, and being higher at east than at west. The meiobenthic abundance and biomass had significant positive correlations with water depth.

Environmental quality assessment of water body and surface sediment in the sea area of Jiaozhou Bay wetland.

2011, 22(10):  2749-2756. 

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Based on the investigation data from 48 sampling stations in the sea area of Jiaozhou Bay wetland in 2009, and by using Nemerow index, eutrophication index (EI), and Hakanson potential ecological risk index, an assessment was conducted on the environmental quality of water body and surface sediment in the sea area. According to the assessment on the 16 indicators including pH, dissolved oxygen (DO), dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorous (DIP), chemical oxygen demand (COD_Mn), petroleum hydrocarbons, Cu, Zn, Pb,Cd, Hg, As,hexachlorocyolohexane (HCH), dichlorodiphenyltrichloroethane (DDT), coliform, and faecal coliform, the water quality was at moderate and serious pollution level in the tidal reach of Dagu River, at slight and moderate pollution level in the intertidal zone, and at slight pollution level in the shallow sea. The eutrophication level differed markedly with the regions, being very serious in the tidal reach of Dagu River (EI value 58.13-327.89), serious in the intertidal zone (EI value 1.34-19.96), and slight in the shallow sea (EI value 0.65-2.10). The surface sediments in the sea area were basically at slight pollution level. The sediment quality was at slight pollution level in the tidal reach of Dagu River, at slight and moderate pollution level in the intertidal zone, and at cleaner and slight pollution level in the shallow sea. The pollution parameter (C_fⁱ) and contamination index (Cd) of the heavy metals in the surface sediments were low, suggesting that the pollution degree was at a lower level. The Cu and Zn were the primary pollution factors in the sediments. The potential ecological risk parameter (E_i^r) and risk index (RI) of the heavy metals in the surface sediments were lower, indicating a slight ecological risk of heavy metals pollution．

Applications of synchrotron-based X-ray absorption near-edge structure spectroscopy in identifying solid state phosphorus speciation: A review.

2011, 22(10):  2757-2764. 

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Solid state phosphorous is an important phosphorus speciation controlling the phosphorous bioavailability and mobility in the environment. Synchrotron-based X-ray absorption near-edge structure(XANES)spectroscopy, with its unique advantage of being a non-destructive method in identifying the local chemical information of target element at molecular level in situ, has become one of the frontier technologies for characterizing the speciation of chemical substances and clarifying the microscopic mechanisms of chemical reactions, attracting extensive attention in the field of environmental chemistry. This paper briefly introduced the basic theory of phosphorus XANES spectroscopy, summarized the applications of XANES spectroscopy in the researches of solid state phosphorus speciation in minerals, soils, and organic fertilizers, and analyzed the challenges and prospects of the applications of XANES spectroscopy in identifying the solid state phosphorus speciation in the environmental samples. It was pointed out that XANES spectroscopy should combine with other microscopic spectroscopic techniques and macroscopic analytical methods, complementing each other, to provide a comprehensive and effective technical support for the research of the speciation characterization and transformation mechanisms of phosphorus in the environment.

Effects of elevated CO₂ concentration on the quality of agricultural products: A review. 

2011, 22(10):  2765-2775. 

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The increasing concentration of atmospheric CO₂ and the nutritional quality of human diets are the two important issues we are facing. At present, the atmospheric CO₂ concentration is about 380 μmol·mol^-1, and to be reached 550 μmol·mol^-1 by 2050. A great deal of researches indicated that the quality of agricultural products is not only determined by inherited genes, but also affected by the crop growth environmental conditions. This paper summarized the common methods adopted at home and abroad for studying the effects of CO₂ enrichment on the quality of agricultural products, and reviewed the research advances in evaluating the effects of elevated CO₂ on the quality of rice, wheat, soybean, and vegetables. Many experimental results showed that elevated CO₂ concentration causes a decrease of protein content in the grains of staple food crops and an overall decreasing trend of trace elements contents in the crops, but improves the quality of vegetable products to some extent. Some issues and future directions regarding the effects of elevated CO₂ concentration on the quality of agricultural products were also discussed, based on the present status of related researches.

Effects of elevated atmospheric CO₂ concentration on mung bean leaf photosynthesis and chlorophyll fluorescence parameters.

2011, 22(10):  2776-2780. 

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By using free air CO₂ enrichment (FACE) system, a pot experiment under field condition was conducted to study the effects of elevated CO₂ concentration (550±60 μmol·mol^-1) on the leaf photosynthesis and chlorophyll fluorescence parameters of mung bean. Comparing with the control (CO₂ concentration averagely 389±40 μmol·mol^-1),elevated CO₂ concentration increased the leaf intercellular CO₂ concentration (C_i) and net photosynthesis rate (P_n) at flowering and pod growth stage by 9.8% and 11.7%, decreased the stomatic conductance (G_s) and transpiration rate (T_r) by 32.0% and 24.6%, respectively, and increased the water use efficiency (WUE) by 83.5%.Elevated CO₂ concentration had lesser effects on the minimal fluorescence (F_o), maximal fluorescence (F_m), variable fluorescence (F_v), ratio of variable fluorescence to minimal fluorescence (F_v/F_o), and ratio of variable fluorescence to maximal fluorescence (F_v/F_m) at bud stage, but increased the F_o at pod filling stage by 19.1% and decreased the F_m, F_v, F_v/F_o, and F_v/F_m by 9.0%, 14.3%, 25.8%, and 6.2%, respectively. These results suggested that elevated CO₂ concentration could damage the structure of leaf photosystemⅡ and consequently decrease the leaf photosynthetic capacity in the late growth phase of mung bean.