Table of Content

15 September 2004, Volume 15 Issue 9

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Dynamics of litters in artificial restoration process of subalpine coniferous forest

LIN Bo, LIU Qing, WU Yan, HE Hai, QIAO Yongkang

2004, (9):  1491-1496. 

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By adopting the concept of space as a substitute for time and taking the primitive subalpine coniferous forests as a reference,this paper investigated the forest litters in 10,30,40,50 and 60-years subalpine Picea asperata stands to study the development process of litters in subalpine coniferous plantations with different restoration stages.The difference in litter development in artificial and natural stands was also discussed.The results indicated that in Picea asperata plantations with different ages,the litter pool on forest floor and the nutrient storage and maximum moisture holding capacity of litters showed a general trend of decrease at their earlier restoration stages,and of increase at the later stages.The trend of increase reached the maximum around 50 years of restoration,and then gradually leveled off or even slightly decreased.The observed litter pool (70.21?10³ kg穐m^-2),nutrient storage (4.73?10³ kg穐m^-2) and maximum moisture holding capacity (89.98?10³ kg穐m^-2) of 60-years plantations were considerably small,only accounted for 48.40%,46.79% and 46.99% of the primitive forests,respectively.After 40 years of restoration,both artificial stands and naturally regenerated secondary forests showed similarity in litter dynamics,annual litterfall,and amount of annual nutrient returning to the soils,while a big difference in litter components,litter pool and structure on the forest floor,nutrient storage,and maximum moisture holding capacity.The difference which accounts for the difference in ecological functioning of the subalpine coniferous plantations lagging behind that of the secondary forests might be mainly caused by the less species diversity of the former.

Effect of different nitrogen supply on Fraxinus mandshurica seedling's biomass,N partitioning and their seasonal variation

FAN Zhiqiang, WANG Zhengquan, WU Chu, LI Hongxin

2004, (9):  1497-1501. 

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Nitrogen is one of the most important limiting nutrients for tree growth in temperature forest ecosystems.In this paper,the effects of nitrogen treatments on nitrogen partition and biomass allocation in roots and leaves of one-year-old Fraxinus mandshurica seedlings were studied during a five-month period.The plants were sand-cultured in pots supplied with various concentrations of N (1,4,8,16 mmol稬^-1).The results suggested that N supply could significantly increase the N concentration in roots and leaves.In the initial (June) and middle growth stage (July and August),the N concentration in leaves was over 9.40,9.55 and 4.21 mg穏^-1 respectively,which was higher than that in roots,but in the latter growth stage (September),it was lower than that in roots.From June to September,the N content of whole plant increased markedly,and was 4 times more in September than in June.The N content in Ash seedlings varied with N supply.It increased by 5.5 times in 16 mmol稬^-1 N treatment,in comparing with 1 mmol稬^-1 N treatment in September.The N allocation also varied in leaf,stem,and root.The proportion of N allocation in leaf was the highest in June (43% in average),and the lowest in September (9% in average).The proportion of N allocation to root increased with plant growth,which was the highest in September (81% in average).Regardless N treatments and tree growth stages,the proportion of N allocation to root was the highest,followed by to leaf,and the lowest was to stem.These results provided the theoretical foundation for the further studies of nitrogen absorption and carbon allocation mechanism in root system of Manchurian ash.

Effect of Ca²⁺ concentration on the growth and bark quality of Pteroceltis tatarinowii

FU Xiangxiang, FANG Shengzuo, TIAN Ye, HONG Saihua

2004, (9):  1502-1506. 

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Hoagland nutrient solutions with three Ca²⁺ concentration levels(5,10 and 15 mmol稬^-1)and a control(no Ca)were used to culture Pteroceltis tatarinowii seedlings.The results indicated that in the control,most seedlings were dead and the survived seedlings were grown poorly,while in three Ca²⁺ concentration treatments,there were no significant differences in seedling height growth and biomass by the end of the experiment.The Ca content in the root,leaf and bark of Pteroceltis tatarinowii increased with increasing Ca²⁺ concentrations,and ranked as root>leaf>bark.Ca treatments had no significant effects on the wood and bark density and the fiber shape traits of one-year seedlings.However,the wood fiber length was the longest and the wood fiber width was the widest at the 10 mmol稬^-1 Ca²⁺ concentration treatment,while the bark fiber length and the ratio of fiber length to fiber width were the best at the 5 mmol稬^-1 Ca²⁺ concentration treatment.Among the three Ca²⁺ concentration treatments,the bark fiber length was over 2 mm,and the ratio of fiber length to fiber width was much higher(about 4 times) than that of the wood.There was a significant difference in cellulose contents of wood and bark of one-year seedlings among the three Ca²⁺ concentration treatments,and the highest cellulose content was achieved at the 10 mmol稬^-1 Ca²⁺ concentration treatment.These results provided some information for the improvement of the growth and bark quality of Pteroceltis tatarinowii grown on non-limestone soil.

Vegetation restoration in western Liaoning hilly region: A study based on succession theory and degradation degree of ecosystem

DU Xiaojun, JIANG Fengqi, JIAO Zhihua

2004, (9):  1507-1511. 

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Based on the analysis of vegetation succession in western Liaoning hilly region,and by the method of Cluster Analysis with some habitat indexes of different succession stage,this paper quantitatively measured the degradation degree of degraded ecosystems in this region.The results showed that the average dissimilarities between natural Quercus forest,natural Chinese pine (Pinus tabulaeformis) forest and Populus-Quercus forest in Nanliuzhangzi forestry centre and Chinese pine plantations in Niuheliang region and Qitian forestry centre were 0.655,0.665,2.029 and 3.919,respectively,and as a whole,the dissimilarities represented the places of the forests in the process of ecosystem succession /degradation.It was also showed that most habitats were degraded to the stage between shrubbery and pioneer arbor forest,and closer to the succession stage of pioneer arbor forest.Some suggestions were made for the management of the existing plantation and the construction of mixed forest,e.g.,to increase the proportion of shrubbery and pioneer arbor species,especially that of nitrogen fixation tree species.The plant species list of several main vegetation types in western Liaoning we offered could provide scientific reference for the vegetation restoration and the management of pure Chinese pine plantation in this region.

Geostatistics analyzing to cause of formation of circle distribution of plant communities in Horqin Sandy Land

HE Xingdong, GAO Yubao, ZHAO Wenzhi, CONG Zili

2004, (9):  1512-1516. 

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Investigation results in the present study showed that plant communities took typical concentric circles distribution patterns along habitat gradient from top,slope to interdune on a few large fixed dunes in middle part of Korqin Sandy Land.In order to explain this phenomenon,analysis of water content and its spatial heterogeneity in sand layers on different locations of dunes was conducted.In these dunes,water contents in sand layers of the tops were lower than those of the slopes; both of them were lower than those of the interdunes.According to the results of geostatistics analysis,whether shifting dune or fixed dune,spatial heterogeneity of water contents in sand layers took on regular changes,such as ratios between nugget and sill and ranges reduced gradually,fractal dimension increased gradually,the regular changes of these parameters indicated that random spatial heterogeneity reduced gradually,and autocorrelation spatial heterogeneity increased gradually from the top,the slope to the interdune.The regular changes of water contents in sand layers and their spatial heterogeneity of different locations of the dunes,thus,might be an important cause resulted in the formation of the concentric circles patterns of the plant communities on these fixed dunes.

Accuracy analysis of vegetation mapping for Meili Snow Mountain area,northwest Yunnan,China

ZHANG Zhiming, OU Xiaokun, WANG Chongyun, WU Yucheng

2004, (9):  1517-1522. 

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The Meili Snow Mountain (28°20'～28°33'N,98°30'～8°52'E) is a very famous mountain in Northwest Yunnan of China by its rich and well protected biodiversity and Tibetan cultural diversity.By applying 3S (RS-Remote Sensing,GIS-Geography Information System,GPS-Global Position System) technology,the 1∶50 000 vegetation map of Meili Snow Mountain area (total about 332 km²) was drawn out.The vegetation in this area was classified into 18 vegetation types except for stone,glacier and river system.The vegetation map was rectified by applying the GPS points got from the fields.The numbers of GPS points were calculated by the formula of numbers of samples in statistics.313 GPS points were used to rectify the vegetation map.The numbers were fit for the formula of numbers of samples in Statistics.The accuracy and verify of vegetation types distribution in the map was analyzed by building a Probability Error Matrix (PEM) and through the variance analysis.The results indicated that the overall accuracy (OA) of the vegetation map was 84.7%.The accuracy of vegetation map finished by 3S technology was lied on the area of the region and the grade of vegetation class first,but the grade of vegetation class classified by remote sensing technology disaccord with the traditional vegetation class system.The other factors deciding the accuracy of vegetation were the distinguish ability of Remote Sensing image,the accuracy of distinguish,and the numbers of the samples,including vegetation class experts knowledge.

Migration dynamics of Grus japonensis in recent years spring and conservation of its habitat in Xianghai Nature Reserve

HE Chunguang, SHENG Lianxi, LANG Huiqing, LI Lianshan, ZOU Lifang

2004, (9):  1523-1526. 

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A survey on the migratory Grus japonensis in Xianghai wetland was conducted in spring of 1997～2003,and the relationship between migratory dynamics of Grus japonensis and changes of wetland eco-environment was analyzed.The population of Grus japonensis in Xianghai was 32,25,64,92,72,59 and 14,respectively in the spring of 1997～2003.The smallest number was found in 2003,only 1 breeding pair,and the largest number was found in 2002,including 16 breeding pairs.The earliest year for Grus japonensis arrival was 2002 (March 12),and the latest year was 2001 (March 28).The earliest year for Grus japonensis laying eggs was 1998 (April 1),and the latest year was 2003 (May 10).Most cranes finished laying eggs in early April.The earliest day was 40 days earlier than the latest one.Among the seven years,the year when the distribution range of Grus japonensis was the widest was 2000,and the cranes mainly distributed in 15 sites,such as Fulaowunpao,Jiandipao,and so on.On the contrary,they distributed only in 2 sites in 1998 and 1 site in 2003.The number and the distribution range of Grus japonensis in 2000 were far larger than those in 1997,1998 and 2003.The migratory dynamics of Grus japonensis changed with the water condition of Xianghai wetland in different years.Based on the characteristics of water eco-environment of Xianghai wetland,a strategy for protecting Grus japonensis by wisely using the flood resource was suggested.

Insect species diversity in Korean pine broad-leaved mixed forest in Changbai Mountains

JI Lanzhu, DONG Baili, WEI Chunyan, WANG Miao

2004, (9):  1527-1530. 

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The study on the insect species diversity in Changbai Mountains showed that there were 1960 insect species belonging to 26 orders,131 families and 1 162 genera,among which,881 species were pests belonging to 11 orders and 105 families,and 638 were serious ones.In forest insect communities,defoliator insect community was more divers than natural enemy community,and predatory insects were more divers than other natural enemies.The indices of annual species evenness of defoliator insect community,parasitic insect community and predatory insect community were 0.884,0.830,and 0.806,respectively,and the diversity changed with season was in the order of predatory insects>parasitic insects>defoliator insects.

Dynamics of soil fauna communities during succession process of secondary forests in Changbai Mountain

TONG Fuchun, WANG Qingli, LIU Xingshuang, XIAO Yihua

2004, (9):  1531-1535. 

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The secondary succession of forest communities in Changbai Mountian might be divided into three stages,i.e.,aggradation,transition,and steady states.The last stage will be arrived after about 100 years.At same time,the succession dynamics of various soil fauna groups were shown as:Saprophagous group was more abundant than other fauna groups,and its change trend was similar to the development of forest vegetation after disturbing;Phytophagous group had a higher amount during the prophase of forest succession,which was decreased with forest succession;the quantity of Carnivorous increased obviously after about 100-years-succession;and the composition of insect groups was that the unstable groups was more abundant when the forest was younger,but less abundant when the forest was older.

Functions of different cultivation modes in oasis agriculture on soil wind erosion control and soil moisture conservation

SU Peixi, ZHAO Aifen, DU Mingwu

2004, (9):  1536-1540. 

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During 2001～2002,the effects of different cultivation modes including winter irrigation and zero tillage,crop-grass intercropping,and early spring film mulching on sand entrainment,wind velocity gradient and soil moisture conservation were studied in the middle reaches of the Heihe River in the Hexi Corridor region.The results showed that all these modes could reduce soil wind erosion and halt sand entrainment to different degrees.Compared with the bare fields exposed by spring plowing,early spring film mulching could increase soil moisture storage by 35.6%.At present,spring plowing and sowing was a main factor responsible to the occurrence of sand storms and the increase in suspended dust content.Farmlands in the upper and middle reaches of the Heihe River generally produced a dust transport up to 4.8～6.0 million tons per year,which was higher than that of sandy desert in the same region.In the Hexi Corridor region,the suspended dust amount produced from 1 hm² farmland was equivalent to that of 1.5 hm² desert.

Mechanism analysis of optimized model of conversion from farmland to forestland in the hill-gully sub-region of Loess Plateau

LI Shidong, ZHANG Lixia

2004, (9):  1541-1546. 

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Conversion from Farmland to Forestland Program (CFF) is one of the six great ecological forest programs in China.This study covered the CFF model area of the hilly-gully sub-region of loess plateau,and introduced system dynamics and other latest theories and methodologies.Based on the analysis of five modules including that of the site observation of field stations and extensive investigations,and over 10 000 original data obtained in the fields of natural science,social science and economics,the operational mechanism of the optimized model was studied.The optimized operational models integrated maximized ecological,economic and social benefits,while sustainability concepts were proposed for typical CFF sites:The Pinus tabulaeformis+Platycladus orientalis+Zanthoxylum spp.+ Robinia pseudoacacia model at the eroded flat ridges of the middle reaches of the Yellow River.The result showed that the ecological,economic and social benefits of the optimized model reflected by main indexes were the best or better,and in the other models,either individual one was the best or others were not.From the viewpoint of comprehensive comparison of three great benefits,the optimized model was most excellent,and had eminent difference comparing to other ones through F test.The relationship between ecological and social benefit was eminent positive correlative.Social benefit was the same with economical one at some degrees.The relationship between ecological and economical benefit was more complicated.On the whole,they were positive correlative,but the economical benefit was not the greatest when the ecological one was the greatest.In general,from the viewpoint of largest comprehensive benefit,the three great benefits were not all the best,indicating that the combination of the modules must be reasonable.In order to achieve the ultimate goal of CFF,we must choose the optimized combination of ecological,economical and social benefits,and can't only pursue any one maximum of three great benefits.

Nutrient and water cycling in red soils with different planting system and their management

HE Yuanqiu, WU Dafu, LI Chengliang, WANG Xingxiang

2004, (9):  1547-1551. 

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Based on the data of long term located experiment,this paper studied the characteristics of nutrient and water cycling and balance and of energy flow in upland red soils with different planting system.The results showed that in red soil areas,the rainfall from March to June accounted for 60% of the whole year,which induced frequent seasonal drought and severe water and soil loss.The application of N,P and K on upland red soil was overabundant and unbalanced,which induced a reduced ratio of input and output.Optimized planting mode could increase the water and light utilization efficiency,decrease the frequency and degree of occurred drought,and increase the nutrient recycling rate.The main measures for rationally developing and utilizing red soil should be establishing compound agro-ecosystem model of planting and feeding,saving irrigation water,increasing mulch,cover-cultivating crops and forests,increasing the proportion of organic fertilizer,realizing rational and balanced fertilization,further optimizing planting structure,regulating energy input structure,and adopting multilevel-technologies of food chain utilization.

Soil respiration characteristics in winter wheat field in North China Plain

CHEN Shuyue, LI Jun, LU Peiling, WANG Yinghong, YU Qiang

2004, (9):  1552-1560. 

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Experiments were conducted at the Yucheng Comprehensive Experimental Station of the Chinese Academy of Sciences during 2002～2003 to investigate the respiration of a pulverous sandstone soil under cultivation of winter wheat over a growth season.The effluent CO₂ was collected and analyzed by the static-chamber/gas chromatography(GC)method at a frequency of once a week in spring and autumn,once two weeks in winter,twice a week for straw manure treatment,once a week for no straw manure treatment and nitrogen fertilization treatment in summer.The results indicated that diurnal variation of soil respiration rate showed a single peak in typical winter wheat farmlands in the North China Plain,and reached the highest at about 13 o'clock,and the lowest at about 4 o'clock in the early morning.In winter wheat growth season,the soil respiration rate was 31.23～606.85 mg·m^-2·h^-1 under straw manure,28.99～549.66 mg·m^-2·h^-1 under no straw manure,10.46～590.86 mg·m^-2·h^-1 in N₀,16.11～349.88 mg·m^-2·h^-1 in N₁₀₀,12.25～415.00 mg·m^-2·h^-1 in N ₂₀₀,and 23.01～410.58 mg·m^-2·h^-1 in N₃₀₀,showing a similar seasonal variation tendency with soil temperature.Among all treatments,the straw manure had the most distinct soil respiration,though the soil respiration also increased slightly with increasing nitrogen fertilization.Soil respiration increased exponentially with increasing soil temperature,and the correlation of soil temperature at the depth of 5 cm was the best.This relationship was usually described with the Q₁₀ model,which represented the sensitivity of soil respiration to temperature.Q₁₀ was not a fixed value,which varied with the depth at which the temperature was measured and the depth of the active soil layer and soil temperature.At same time,the Q₁₀ value decreased with increasing soil temperature.Soil water content was another important factor affecting soil respiration rate,but in this region,the relationship between soil respiration and soil moisture was poor,and no distinct rules were shown.The average net photosynthesis rate of winter wheat had a close relation with soil respiration rate.The differences between them showed that the photosynthetic uptake of CO₂ was beyond emission of soil respiration during the period from return green to mature,and the winter wheat farmland was a sink of CO₂.

Effects of fertilization on the growth,photosynthetic characteristics and yield of Coffea arabica

CAI Zhiquan, CAI Chuantao, QI Xin, YAO Tianquan

2004, (9):  1561-1564. 

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Coffea arabica is a major economic plant in agriculture plantation in tropical and subtropical areas in the world.This paper reports the experimental results on the fertilization strategy in Yunnan,China.Effects of varied levels of nitrogen (N),phosphorus (P),potassium (K) nutrients on the growth,photosynthetic characteristics and yield in three-year old saplings of C.arabica with the density of 4 500 individuals per hectare were measured.In general,N is the most important factor influencing the growth,photosynthetic capacity and yield of C.arabica,followed by K and P,respectively.The yield can be improved through spraying appropriate amount of trace elements in the leaves.The optimum matching experiments in fertilization level of N∶P₂O₅∶K₂O is at the ratio of 1∶0.5∶1.The high yield of C.arabica need high nutrient demands,but the optimum amount of fertilizer of N,P₂O₅,K₂O is 100,50,100 g per individual according to the cost-benefits analysis.The yield of C.arabica was closely related with the numbers of branch,total leaf areas and maximum rate of net photosynthesis (A_max) among different treatments.Different fertilization strategy had no significantly effects on the photochemical efficiency in dawn,but all indicators showed that the higher-fertilized plants could significantly alleviate diurnal photoinhibition.

Relationship between wheat root activity and leaf senescence

WEI Daozhi, NING Shuju, LIN Wenxiong

2004, (9):  1565-1569. 

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A field trial on the wheat root activity, chlorophyll content and photosynthetic rate showed that the decline of root activity was earlier and faster than that of flag leaf chlorophyll content and photosynthetic rate, and there was a positive correlation between root activity and leaf photosynthetic rate(r=0.8006).Topdressing nitrogen fertilizer at elongation stage could obviously improve root activity and photosynthetic rate, decrease leaf ABA con-tent, increase ZRs content and SOD activity, and delay the peak value of MDA for 8～10 days, which suggested that the variation of root activity was closely related to the senescence of flag leaf. Improving root nutrition and root activity at earlier growth stages could delay the senescence of wheatleaf.

Transformation characteristics of sulfur forms in acid sulfate soils under different soil water conditions

LIU Zhenqian, DUAN Shunshan, LI Aifen, XU Ning, WANG Jianwu, LI Minghui

2004, (9):  1570-1574. 

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Aimed to detect the quantitative impact of soil water condition on the transformation of sulfur forms in acid sulfate soils(ASS),a simulation test was made with 8 treatments.The results indicated that water was an important factor affecting the transformation processes.Wet but not inundated or over dried condition was benefit to the oxidation of pyrite S and the formation of water soluble S (WS-S) and exchangeable S (Ex-S) in ASS.In the three treatments with different inundated and drained off cycles,soil pyrite S content averagely decreased 1.29～3.20 g·kg^-1 during a single drained off period,while soil WS-S and Ex-S contents averagely increased 0.90～1.63 and 0.58～1.47 g·kg^-1,respectively.During inundated period,soil pyrite S content was relatively stable,but soil WS-S and Ex-S contents were decreased significantly due to the dilution of water.It was suggested that the total S(mainly WS-S)of ASS was discharged in drainage process,and the accumulative amount of the discharge and the transformation of the S forms were associated with the length of the inundated and drained off cycles.The dynamics of Jarosite S,organic S and element S in all treatments were also discussed here.

Evaluation efficiency of different bioassay methods on allelopathic potential of Oryza sativa

SHEN Lihua, LIANG Yiyuan, HE Huaqin, HE Jun, LIANG Kangjing, LIN Wenxiong

2004, (9):  1575-1579. 

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In this paper,three bioassay methods,i.e.,relay seeding in agar(RSA),relay seeding in silica(RSS) and seeding in rice root-exudation(SRE),were used to test the allelopathic potential of 8 rice cultivars on the target weed barnyardgrass(Echinochloa crusgalli).The results indicated that RSA was the ideal method for the bioassay,showing the highest efficiency in the evaluation of allelopathic potential.RSS and SRE had a lower efficiency than RSA,but these two methods showed the same tendency in evaluating the allelopathic potential of rice.RSA,the considered best bioassay method in this experiment,was used for 57 allelopathic rice germplasm screening,and 5 of them,i.e.,Iguape Cateto,PI312777,Azucena,Taichung Native 1 and IAC25 performed the strongest allelopathic potential in the suppression on barnyardgrass.

Interference of allelopathic rice cultivars on barnyardgrass under different water irrigation and rice plant density

XU Zhenghao, HE Yong, WANG Yiping, YU Gusong

2004, (9):  1580-1584. 

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Pot culture experiments were conducted to examine the effects of water irrigation and rice plant density on the interference of allelopathic rice on barnyardgrass (Echinochloa crus-galli).The results showed that under water irrigations,allelopathic rice cultivars Xiayitiao,Gumei 2 and Zhong 156 significantly reduced the plant height of barnyardgrass than non-allelopathic rice cultivars Xiushui 63 and Chunjiang 11.Barnyardgrass plants grew shorter as rice plant density increased.Allelopathic rice cultivars Jizaoxian and Gumei 2 interfered with barnyardgrass,even at their densities as low as 4 plants per pot,and the interference reduced plant height of barnyardgrass significantly compared with the non-rice control.Allelopathic rice cultivars Xiayitiao,Jizaoxian,PI312777,TN1,Gumei 2 and Zhong 156 at 32 rice plants per pot inhibited the growth of barnyardgrass significantly than Chunjiang 11.

Interaction between AM fungi and Rhizobium and effects of flavonoids on it

DONG Changjin, ZHAO Bin

2004, (9):  1585-1588. 

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Study showed that the biomass and nodule number of Astragalus sinicus,AM fungal infection rate,and hyphal enzyme activity of ALP and SDH were significant influenced by Rhizobium,AM fungi and flavonoids.Rh+AMF treatments had obvious differences with control in the biomass and nodule numbers of Astragalus sinicus,AM fungal infection rate and hyphal enzyme activity;and flavonoid treatments had more obvious differences with Rh+AMF treatments and control in these aspects,but no obvious differences were found in different flavonoids (apigenin and hesperitin) or in different concentrations (150 nmol·L^-1 and 1.5 μmol·L^-1) of the same flavonoid.The results showed that nodule-generation and nitrogen-fixation of Rhizobium and AM fungi infection were obvious promoted by Rhizobium and AM fungi,and this promotion effects were more significant when an appropriate amount of flavonoids was added in the Rh+AMF treatments.

Temporal and spatial variations of chemical constituents in maize

CHEN Yuxiang, ZHOU Daowei, ZHANG Yufen

2004, (9):  1589-1593. 

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Study on the temporal and spatial variations of chemical constituents in maize showed that with the development of maize,the contents of total starch,crude protein and crude lipid in its kernel increased,while those of crude protein and crude lipid in its leaf and stem decreased.The content of fiber extracted by neutral agent and that of fiber and lignin in leaves and stems increased.The crude protein content of the top leaf was higher than that of the basal leaf,while the content of fiber extracted by neutral agent and that of fiber and lignin in the top leaf were lower than those of the basal leaf.The crude protein content of the top stem was higher than that of the basal stem,while the content of the fiber extracted by neutral agent and that of the fiber and lignin in the top stem were lower than those of the basal stem.

Features of grassland resources and their classified management in Alatai region of Xinjiang

GUO Zhenggang, LIANG Tiangang, LIU Xingyuan

2004, (9):  1594-1598. 

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Grassland degradation,an important problem in grassland management,has affected the sustainable development of animal husbandry in Alatai region of Xinjiang.Based on the analysis of the community features,ecological service value and multiple functions,and main function of grassland types in the regional development,the classified management for grassland was designed.The results showed that Alatai grassland could be divided into three sectors,i.e.,ecological function region,economic function region and mixed function region.The ecological function region made up 164.66?10⁴ hm² or 16.73% of total Alatai grassland,and the grassland types included alpine meadow,alpine rangeland,swamp,mountain desert steppe,mountain steppe desert and part of plain desert.For the ecological function region,the main management strategy was to prohibit grazing and cropping.The economic function region of 116.33?10⁴ hm² accounted for 11.82% of the total Alatai grassland,the grassland types included mountain meadow,flat meadow and meadow steppe,and the main management strategy to enhance the productivity was agricultural measures,such as fertilization and irrigation.The mixed function region which included mountain steppe,plain desert steppe and most part of plain desert was 703.21?10⁴ hm² or 71.45% of total Alatai grassland,and the main management strategy was rotational grazing.

Species diversity of pasture community at different altitude levels in Qilian Mountains

CHANG Xuexiang, ZHAO Wenzhi, ZHAO Aifen

2004, (9):  1599-1603. 

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According to the occurring frequency and life form of plant species at different altitude levels,this paper studied the changing characteristics of the species α diversity of pasture community at the altitude from 2 500 m to 3 000 m in Qilian Mountains.The results showed that with increasing altitude,the Shannon-Wiener species diversity index increased from 1.432 to 1.832,and the variety of Simpson index was very complicated.An altitude of 2 701～2 800 m was an important turning point for species diversity.In pasture community of Qilian Mountains,the percentage of the poisonous and the less edible species exceeded 50%,and their biomass was more than 60% of the total biomass of the community.The biodiversity showed a degraded trend.

Soil C and N dynamics during desertification of grassland in Northern China

LIU Yingru, YANG Chi, ZHU Zhimei, LIU Meiling

2004, (9):  1604-1606. 

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This paper investigated the aboveground vegetations and the soil texture and total C and N at 75 sites of Duolun County in Xilinguole League of Inner Mongolia.The results showed that different types of vegetation community could be used to describe different stages of desertification process.During desertification,the community types were changed in the series of Leymus chinensis+Cleistogenes squarrosa → Artemisia frigida → Artemisia intramongolia → Corispermum staunyonii,Chenopodium bryoniaefolium → drift sand,and a regular change of soil clay and total C and N contents could also be found.The soil C/N ratio was increased with different stages of grassland desertification,which could be expressed in the series of 8.11→13.96→12.36→28.17.

Community features of Scarabaeoidea larvae in Stipa grandis steppe

LIU Xinmin, WU Ning

2004, (9):  1607-1610. 

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The study showed that in the Stipa grandis steppe of Inner Mongolia,there were 4 families and 9 species of Scarabaeoidea larvae,among which,the numbers of species and individuals of Melolonthidae were more than those of other families.The important value of the dominant species in Scarabaeoidea larvae community were Trematodes tenebrioides >Serica orientalis >Amphimallon solstitialis >Cyriopertha arcuata.Based on the features of their seasonal dynamics,they could be classified into three kinds.The first kind was that their density peak occurred in spring and autumn,such as Serica orientalis.Cyriopertha arcuata belonged to the second kind,and its density had no obvious fluctuation through all the year.Trematodes tenebrioides and Amphimallon solstitialis could be classified into the third kind,and their density peak all occurred in autumn.The biodiversity index of Scarabaeoidea larvae community was relatively higher in autumn than in spring and summer.Although the richness of Scarabaeoidea larvae populations was not lower in spring,their composition was very simple.

A comparative study on soil respiration between grazing and fenced typical Leymus chinensis steppe,Inner Mongolia

JIA Bingrui, ZHOU Guangsheng, WANG Fengyu, WANG Yuhui

2004, (9):  1611-1615. 

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With enclosed chamber Method,this paper studied the soil respiration in grazing and fenced typical Leymus chinensis steppes,Inner Mongolia,and its relationships with environmental factors.The results showed that the daily pattern of soil respiration could be expressed as a one-humped curve,and the highest values appeared at 13:00～15:00 in the fenced and grazing plots.The diurnal dynamics of soil respiration mainly depended on the surface temperature at the fenced plots and the soil temperature at 5 cm depth at the grazing plots.In June and July,the average soil respiration rate was 2.7 times greater at the fenced plots than that at the grazing plots,while the difference was not distinct in August and September,which was similar with the change of the belowground biomass.The reason was probably that the plant was influenced differently in different phenological phases by grazing and the change of environmental factors.It showed that human activity may not result in the increase of soil respiration rate.The seasonal dynamics of soil respiration was closely correlated with soil water content at the 0～10 cm depth at the fenced and grazing sites,and the maximum R² was 0.853 and 0.741,respectively.The difference was that the correlation of soil respiration seasonal dynamics with soil water content was larger at the fenced plots than at the grazing plots.The correlations of soil respiration diurnal and seasonal dynamics with temperature and soil water content at lower profiles were larger than those at deeper profiles at the fenced and grazing sites.

Dynamics and ecological significance of nitrogen wet-deposition in Taihu Lake region—Taking Changshu Agro-ecological Experiment Station as an example

WANG Xiaozhi, ZHU Jianguo, GAO Ren, HOSEN Yasukazu

2004, (9):  1616-1620. 

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Nitrogen wet deposition was monitored for two years (2001.6～2003.5) at the Changshu Ecological Station in Taihu Lake region.The results showed that the amount of nitrogen wet deposition had a strong seasonal pattern,with higher levels in summer and spring,and low values in autumn and winter.The proportions of NH₄^{+3-4+4+R2=0.3178 **),while the monthly NO₃-R2=0.1985 *) with monthly rainfall but positively related with the time of rainfall (R2=0.6757 ***).The NO₃-R2=0.4205 ***).The annual TN input from wet deposition was 27.0 kg·hm-2,but its concentration in each rainfall was higher than 0.2 mg·L-1 (the threshold N concentration for inland water eutrophication).The nitrogen inputted by wet deposition had an ecological significance on both nitrogen balance in agroecosystem and eutrophication.}

Sensitivity of Chlorella vulgaris to metribuzin,puma and alachlor

YANG Zhiqiang, DONG Bo, WU Jincai

2004, (9):  1621-1625. 

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The relative sensitivities of Chlorella vulgaris to three commonly used herbicides metribuzin,puma and alachlor were determined by toxicity tests of 96-h static exposures.The results showed that the toxicities of metribuzin and alachlor to C.vulgaris increased with exposure time,and the density of C.vulgaris decreased with increasing concentrations of these two herbicides in the test media.The maximum specific growth rate of C.vulgaris exposed to metribuzin (0.24 mg稬^-1) and alachlor (12.8 mg稬^-1) was 12.38% and 31.58% of the control,respectively.At low concentration,puma stimulated C.vulgaris growth,but at high concentration,it inhibited the growth significantly.The maximum specific growth rate of C.vulgaris under 0.08 mg稬^-1 puma was 111.44% of the control,and the toxicity of puma declined with increasing exposure duration.The EC₅₀ value of metribuzin,puma and alachlor was 0.021,0.937,and 5.54 mg稬^-1,respectively.The relative sensitivities of C.vulgaris to the three herbicides decreased in the order of metribuzin,puma and alachlor.The chlorophyll a content of C.vulgaris decreased with the increasing concentrations of metribuzin,puma and alachlor.

Molecular genetic diversity of phytoplankton rbcL gene in Jiaozhou Bay

LIU Yongjian, YANG Guanpin, GUAN Xiaojing

2004, (9):  1626-1632. 

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The variants of a 500 base pair fragment of RubisCo large subunit gene(rbcL)from the phytoplanktonic DNA of Jiaozhou Bay surface seawater were amplified by using polymerase chain reaction and cloned.Twenty-eight clones were randomly selected and sequenced,which were further used to determine the molecular genetic diversity of the phytoplankton of Jiaozhou Bay surface seawater.Systematic analysis showed that the clones representing cryptophyta counted for 28.6%,Stramenopiles 32.1%,Haptophyta 28.6%,Rhodophyta 3.6% and Chlorophyta 7.1%.The sequences from Cryptophyta,Stramenopiles,Haptophyta and Rhodophyta belonged to type D of Form I rbcL and Chlorophyta to type B,indicating that the dominant phytoplankton were those represented by type D rbcL.The genetic diversity index and the reversely translated amino acid sequence diversity of Jiaozhou Bay phytoplankton were 2.85 and 0.20,which were determined by the abundances of operational taxonomy units and the reversely translated amino acid sequences respectively.

A primary study on antimicrobial and cytotoxic activity of marine bacteria

ZHENG Li, LIN Wei, YAN Xiaojun, CHEN Haimin

2004, (9):  1633-1636. 

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Marine bacteria were isolated from marine organisms including invertebrates and seaweeds and from sea water and sediments of different sea area.Ethyl acetate extractions of marine bacterial fermentation were screened for antimicrobial and cytotoxicity activities by using the methods of agar diffusion and MTT assay,and the relationship of active bacteria and their origin was studied.The results showed that 42 strains among total 341 isolated marine bacteria had antimicrobial activity,and 7 strains had cytotoxicity activity.The proportion of active bacteria associated with marine invertebrates and seaweeds (22% and 11%) was higher than that isolated from sea water and sediments (7% and 5%).The most active marine bacteria were assigned to the Pseudomonas,Photobacterium,Clostridium,Alteromonas and Flavobacterium group.

Effects of environmental factors on catch variation of main species of stow net fisheries in East China Sea

ZHOU Sufang, FAN Wei, CUI Xuesen, CHENG Yanhong

2004, (9):  1637-1640. 

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Stow net fishery is one of the important fishing methods in the East China Sea.This paper used the generalized additive models (GAMs) to quantitatively describe the relationships between stow net catch and environmental factors (sea surface temperature SST,water depth,fishing position and tide) in the East China Sea.The results indicated that each factor had its own nonlinear effect on the catch per unit effort (CPUE) of haitail (Trichiurus japonicus),small yellow croaker (Larimichthys polyactis) and butter fish (Pampus spp.),and SST and water depth were the key factors.The GAMs' fitting results showed that SST had the strongest effect on the catch per unit effort of haitail,and water depth had the second one.The effects of fishing location and tide were very small.Water depth was the most influential variable when adjusted for the effects on small yellow croaker.SST,fishing location and tide had similar effects.Meanwhile,water depth and SST were the key factors affecting the catch per unit effort of butter fish.They had similar intensity.

Plant physiological and molecular biological mechanism in response to aluminium toxicity

LIU Qiang, ZHENG Shaojian, LIN Xianyong

2004, (9):  1641-1649. 

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Aluminium toxicity is the major factor limiting crop growth on acid soils,which greatly affects the crop productivity on about 40% cultivated soils of the world and 21% of China.In the past decades,a lot of researches on aluminium toxicity and resistant mechanisms have been doing,and great progress was achieved.This paper dealt with the genetic differences in aluminium tolerance among plants,screening and selecting methods and technologies for identifying aluminium resistance in plants,and physiological and molecular mechanism resistance to aluminium toxicity.Some aspects needed to be further studied were also briefly discussed.

Recent advances in research and application of associated nitrogen-fixation with graminaceous plants

ZHANG Limei, FANG Ping, ZHU Riqing

2004, (9):  1650-1654. 

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The category, characteristic of diazotrophs isolated from inside and/or rhizosphere of graminaceous plants in recent year and the mechanism of the promoting effects on their host plant were reviewed in this paper. The current status of application of associative nitrogen-fixation inoculants and the problems in inoculation were discussed. It was indicated that the main factors influencing the effects of inoculants include the competition of indigenous micro-organism with inoculants for nutritions and energy, difference of host plant genotypes in associative relationship, and variance of environmental conditions such as the concentration of ammonium in soil solution and the oxygen partial pressure in soil air. The trends of future research in this field were prospected, for example, to isolate and identify the high nitrogen fixing efficiency strains with wider environmental adaptability, to create associative nitrogen fixing bacteria strain which is able to bear or endure higher concentration of ammonium by gene engineering technique, to induce graminaceous plant forming root nodule for nitrogen fixation and to exert the predominance of endophytic diazotrophs.

A review on research of implement application for crop simulation model in regional scale by using remote sensing technology

MA Yuping, WANG Shili

2004, (9):  1655-1661. 

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When applying crop simulation model developed from plot-scale level to regional scale,some challenges such as acquirement of some broader spatial data and regionalization of parameters will arise,while satellite can monitor crop growth status by remote sensing.Therefore,regional application of crop simulation model will be implement by remote sensing technique.In this paper,some research advances are reviewed,which include the methods of biophysical parameters retrieved from remote sensing data for crop model,the approach of biomass obtained by remote sensing data directly,and the means of matching temporal and spatial resolution between remote sensing data and crop model input.Three solutions (forcing,recalibration and validation) to the application of crop model in region scale by using remote sensing technique were emphasized,and the current problem and future research orientation in this filed were discussed in brief.

Function of artificial grassland in restoration of degraded natural grassland and its research advance

NIU Shuli, JIANG Gaoming

2004, (9):  1662-1666. 

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This paper analyzed the degradation actuality of natural grassland,its reasons and corresponding restoration ways.Natural restoration is the easiest way,but it is very slow.The establishment of some artificial grassland is the most effective way to lessen the oppressiveness of natural grassland.The research advances on artificial grassland were summarized,and the ways for promoting the sustainable development of pasturing area were suggested.Considering the high productivity,planting forage maize may be an available attempt in Hunshandak Sandland.

Relationship between vegetable nutrition and nitrate content

LI Huihe, WANG Zhengyin, LI Baozhen

2004, (9):  1667-1672. 

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Nitrate accumulation in vegetables,which related well to vegetable nutrition,becomes one of the limiting factors of non-pollution vegetables production.Preference to nitrate is the nutritional characteristic of vegetables.Nitrate is absorbed by vegetables through high-affinity transport system(HATS)and low-affinity transport system(LATS),and is reduced and transformed under the effect of such essential elements as molybdenum,manganese,iron,copper,sulphur and phosphorus.In this paper,the effects of essential elements on nitrate absorption and reductive transform were reviewed,and the relationships of nitrate accumulation in vegetables with vegetable nutrition of nitrogen,phosphorus,potassium and mid-and microelements as well as with balanced fertilization were discussed.The research keys in the field were prospected for controlling nitrate accumulation,improving vegetables' quality and producing non-pollution vegetables.

Application of plant polyphenols in environmental protection and agricultural production

FU Meiyun, ZHOU Lixiang

2004, (9):  1673-1677. 

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Plant polyphenols,the secondary metabolites in plant,contain many phenol-hydroxyl groups.They can bind with protein,alkaloids and polysaccharides,and consequently,exhibit an astringent property.Plant polyphenols can also bind with metal ions to form polyphenol-metal complexes,which are probably soluble or precipitated,depending on the type of plant polyphenols.Up to now,about 600 plant polyphenols have been found.Plant polyphenols can be applied widely in environmental pollution control and agriculture production.

Spatial variability and quantitative analysis of field factors based on GIS

CHEN Rongrong, ZHOU Zhiguo, CAO Weixing, DAI Tingbo

2004, (9):  1678-1680. 

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The objective of this research was to investigate the variability and the quantitative relationships among soil nutrients and crop growth status and yield.All data were analyzed by both classical statistics and geostatistics based on GIS.Soil properties included soil pH,total N,organic matter,available P and available K,while crop growth status was indicated by SPAD,LAI and SPAD譒AI.All parameters except soil pH exhibited spatial correlation.Soil total N and organic matter,SPAD,LAI and SPAD譒AI were all correlated to rice yield.Kriged interpolation maps provided good indication of the spatial variability in crop yield and growth status.Spatial interpolation and correlation analysis proved that SPAD譒AI was more indicative of crop growth status than individual variables,and useful for implementing growth season and topdressing as needed.

Effect of acid rain on mercury leaching from forest yellow soil in Jinyun Mountain

LI Jing, WEI Shiqiang, YANG Xuechun

2004, (9):  1681-1683. 

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Forest yellow soil and arable yellow soil in Jinyun Mountain were collected to study the effect of simulated acid rain(adjusted to pH 2.0,3.0,4.0 and 5.0) on the Hg leaching from soils by the methods of static extraction and dynamic leaching.The results showed that in forest yellow soils,surface accumulation of Hg occurred,and the accumulated Hg was easier to be leached out than that in arable yellow soil by acid rain.The amount of leached Hg was the largest at pH 4.0.To abate the risk of Hg pollution in water bodies by the Hg leaching from this forest soil,the Mountain should be closed,and timber-felling should be forbidden.

Rapid measurements of CO₂ flux density and water use efficiency of crop community

ZHU Zhilin, SUN Xiaomin, ZHANG Renhua, SU Hongbo, TANG Xinzai

2004, (9):  1684-1686. 

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In this paper,Eddy Correlation (EC) method was employed to measure the latent heat and CO₂ flux density and to calculate Water Use Efficiency (WUE) of winter wheat community in Yucheng district,Shandong Province in 1997.The results showed that the CO₂ flux density had an obvious diurnal change,with a maximum about1.5 mg·s^-1·m^-2,which appeared at about 9:00～10:00 am in general.The WUE of wheat community presented a fall trend from morning to afternoon,and the CO₂ flux density and WUE also had an obvious seasonal change,being lower in the early and late growth stages,and higher in the middle growth stage.The ranges of daily mean CO₂ flux density and WUE were 0.2～0.9 mg·s^-1·m^-2 and 5～20 gCO₂·kg^-1 H₂O,respectively.

Bioassay on oviposition repellency of non-preferable plant extracts against citrus red mite Panonychus citri

CEN Yijing, PANG Xiongfei, ZHOU Qiong, PENG Yuefeng, XU Changbao

2004, (9):  1687-1690. 

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The oviposition repellency of the alcohol extracts from 50 species of non-preferable plants and azadirachtin against citrus red mite (Panonychus citri) was determined using laboratory bioassays.In choice tests,the extracts from 42 of the 50 plant species and 1% azadirachtin (2000@) significantly reduced oviposition 1d after treatment.The repellency effect of the extracts from the 42 plant species was better than that of azadirachtin.Mikania micrantha extract had the best result,with an Interference Index of Population Control (IIPC) of 0.087 1 d after treatment,and significantly reduced oviposition for 9 d,while the extracts from Sesbania cannabina,Allium tuberosum,Paederia scandens,Duranta erecta and Dicranopteris pedata also had good effects,with an oviposition repellency of over 70% 1 d after treatment,and significantly reduced oviposition for 4～6 d.The effect became weaker as time went on.None of the extracts showed significant oviposition attraction.

Dynamics of litters in artificial restoration process of subalpine coniferous forest

LIN Bo, LIU Qing, WU Yan, HE Hai, QIAO Yongkang

2004, (9):  1491-1496. 

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By adopting the concept of space as a substitute for time and taking the primitive subalpine coniferous forests as a reference,this paper investigated the forest litters in 10,30,40,50 and 60-years subalpine Picea asperata stands to study the development process of litters in subalpine coniferous plantations with different restoration stages.The difference in litter development in artificial and natural stands was also discussed.The results indicated that in Picea asperata plantations with different ages,the litter pool on forest floor and the nutrient storage and maximum moisture holding capacity of litters showed a general trend of decrease at their earlier restoration stages,and of increase at the later stages.The trend of increase reached the maximum around 50 years of restoration,and then gradually leveled off or even slightly decreased.The observed litter pool (70.21?10³ kg穐m^-2),nutrient storage (4.73?10³ kg穐m^-2) and maximum moisture holding capacity (89.98?10³ kg穐m^-2) of 60-years plantations were considerably small,only accounted for 48.40%,46.79% and 46.99% of the primitive forests,respectively.After 40 years of restoration,both artificial stands and naturally regenerated secondary forests showed similarity in litter dynamics,annual litterfall,and amount of annual nutrient returning to the soils,while a big difference in litter components,litter pool and structure on the forest floor,nutrient storage,and maximum moisture holding capacity.The difference which accounts for the difference in ecological functioning of the subalpine coniferous plantations lagging behind that of the secondary forests might be mainly caused by the less species diversity of the former.

Effect of different nitrogen supply on Fraxinus mandshurica seedling's biomass,N partitioning and their seasonal variation

FAN Zhiqiang, WANG Zhengquan, WU Chu, LI Hongxin

2004, (9):  1497-1501. 

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Nitrogen is one of the most important limiting nutrients for tree growth in temperature forest ecosystems.In this paper,the effects of nitrogen treatments on nitrogen partition and biomass allocation in roots and leaves of one-year-old Fraxinus mandshurica seedlings were studied during a five-month period.The plants were sand-cultured in pots supplied with various concentrations of N (1,4,8,16 mmol稬^-1).The results suggested that N supply could significantly increase the N concentration in roots and leaves.In the initial (June) and middle growth stage (July and August),the N concentration in leaves was over 9.40,9.55 and 4.21 mg穏^-1 respectively,which was higher than that in roots,but in the latter growth stage (September),it was lower than that in roots.From June to September,the N content of whole plant increased markedly,and was 4 times more in September than in June.The N content in Ash seedlings varied with N supply.It increased by 5.5 times in 16 mmol稬^-1 N treatment,in comparing with 1 mmol稬^-1 N treatment in September.The N allocation also varied in leaf,stem,and root.The proportion of N allocation in leaf was the highest in June (43% in average),and the lowest in September (9% in average).The proportion of N allocation to root increased with plant growth,which was the highest in September (81% in average).Regardless N treatments and tree growth stages,the proportion of N allocation to root was the highest,followed by to leaf,and the lowest was to stem.These results provided the theoretical foundation for the further studies of nitrogen absorption and carbon allocation mechanism in root system of Manchurian ash.

Effect of Ca²⁺ concentration on the growth and bark quality of Pteroceltis tatarinowii

FU Xiangxiang, FANG Shengzuo, TIAN Ye, HONG Saihua

2004, (9):  1502-1506. 

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Hoagland nutrient solutions with three Ca²⁺ concentration levels(5,10 and 15 mmol稬^-1)and a control(no Ca)were used to culture Pteroceltis tatarinowii seedlings.The results indicated that in the control,most seedlings were dead and the survived seedlings were grown poorly,while in three Ca²⁺ concentration treatments,there were no significant differences in seedling height growth and biomass by the end of the experiment.The Ca content in the root,leaf and bark of Pteroceltis tatarinowii increased with increasing Ca²⁺ concentrations,and ranked as root>leaf>bark.Ca treatments had no significant effects on the wood and bark density and the fiber shape traits of one-year seedlings.However,the wood fiber length was the longest and the wood fiber width was the widest at the 10 mmol稬^-1 Ca²⁺ concentration treatment,while the bark fiber length and the ratio of fiber length to fiber width were the best at the 5 mmol稬^-1 Ca²⁺ concentration treatment.Among the three Ca²⁺ concentration treatments,the bark fiber length was over 2 mm,and the ratio of fiber length to fiber width was much higher(about 4 times) than that of the wood.There was a significant difference in cellulose contents of wood and bark of one-year seedlings among the three Ca²⁺ concentration treatments,and the highest cellulose content was achieved at the 10 mmol稬^-1 Ca²⁺ concentration treatment.These results provided some information for the improvement of the growth and bark quality of Pteroceltis tatarinowii grown on non-limestone soil.

Vegetation restoration in western Liaoning hilly region: A study based on succession theory and degradation degree of ecosystem

DU Xiaojun, JIANG Fengqi, JIAO Zhihua

2004, (9):  1507-1511. 

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Based on the analysis of vegetation succession in western Liaoning hilly region,and by the method of Cluster Analysis with some habitat indexes of different succession stage,this paper quantitatively measured the degradation degree of degraded ecosystems in this region.The results showed that the average dissimilarities between natural Quercus forest,natural Chinese pine (Pinus tabulaeformis) forest and Populus-Quercus forest in Nanliuzhangzi forestry centre and Chinese pine plantations in Niuheliang region and Qitian forestry centre were 0.655,0.665,2.029 and 3.919,respectively,and as a whole,the dissimilarities represented the places of the forests in the process of ecosystem succession /degradation.It was also showed that most habitats were degraded to the stage between shrubbery and pioneer arbor forest,and closer to the succession stage of pioneer arbor forest.Some suggestions were made for the management of the existing plantation and the construction of mixed forest,e.g.,to increase the proportion of shrubbery and pioneer arbor species,especially that of nitrogen fixation tree species.The plant species list of several main vegetation types in western Liaoning we offered could provide scientific reference for the vegetation restoration and the management of pure Chinese pine plantation in this region.

Geostatistics analyzing to cause of formation of circle distribution of plant communities in Horqin Sandy Land

HE Xingdong, GAO Yubao, ZHAO Wenzhi, CONG Zili

2004, (9):  1512-1516. 

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Investigation results in the present study showed that plant communities took typical concentric circles distribution patterns along habitat gradient from top,slope to interdune on a few large fixed dunes in middle part of Korqin Sandy Land.In order to explain this phenomenon,analysis of water content and its spatial heterogeneity in sand layers on different locations of dunes was conducted.In these dunes,water contents in sand layers of the tops were lower than those of the slopes; both of them were lower than those of the interdunes.According to the results of geostatistics analysis,whether shifting dune or fixed dune,spatial heterogeneity of water contents in sand layers took on regular changes,such as ratios between nugget and sill and ranges reduced gradually,fractal dimension increased gradually,the regular changes of these parameters indicated that random spatial heterogeneity reduced gradually,and autocorrelation spatial heterogeneity increased gradually from the top,the slope to the interdune.The regular changes of water contents in sand layers and their spatial heterogeneity of different locations of the dunes,thus,might be an important cause resulted in the formation of the concentric circles patterns of the plant communities on these fixed dunes.

Accuracy analysis of vegetation mapping for Meili Snow Mountain area,northwest Yunnan,China

ZHANG Zhiming, OU Xiaokun, WANG Chongyun, WU Yucheng

2004, (9):  1517-1522. 

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The Meili Snow Mountain (28°20'～28°33'N,98°30'～8°52'E) is a very famous mountain in Northwest Yunnan of China by its rich and well protected biodiversity and Tibetan cultural diversity.By applying 3S (RS-Remote Sensing,GIS-Geography Information System,GPS-Global Position System) technology,the 1∶50 000 vegetation map of Meili Snow Mountain area (total about 332 km²) was drawn out.The vegetation in this area was classified into 18 vegetation types except for stone,glacier and river system.The vegetation map was rectified by applying the GPS points got from the fields.The numbers of GPS points were calculated by the formula of numbers of samples in statistics.313 GPS points were used to rectify the vegetation map.The numbers were fit for the formula of numbers of samples in Statistics.The accuracy and verify of vegetation types distribution in the map was analyzed by building a Probability Error Matrix (PEM) and through the variance analysis.The results indicated that the overall accuracy (OA) of the vegetation map was 84.7%.The accuracy of vegetation map finished by 3S technology was lied on the area of the region and the grade of vegetation class first,but the grade of vegetation class classified by remote sensing technology disaccord with the traditional vegetation class system.The other factors deciding the accuracy of vegetation were the distinguish ability of Remote Sensing image,the accuracy of distinguish,and the numbers of the samples,including vegetation class experts knowledge.

Migration dynamics of Grus japonensis in recent years spring and conservation of its habitat in Xianghai Nature Reserve

HE Chunguang, SHENG Lianxi, LANG Huiqing, LI Lianshan, ZOU Lifang

2004, (9):  1523-1526. 

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A survey on the migratory Grus japonensis in Xianghai wetland was conducted in spring of 1997～2003,and the relationship between migratory dynamics of Grus japonensis and changes of wetland eco-environment was analyzed.The population of Grus japonensis in Xianghai was 32,25,64,92,72,59 and 14,respectively in the spring of 1997～2003.The smallest number was found in 2003,only 1 breeding pair,and the largest number was found in 2002,including 16 breeding pairs.The earliest year for Grus japonensis arrival was 2002 (March 12),and the latest year was 2001 (March 28).The earliest year for Grus japonensis laying eggs was 1998 (April 1),and the latest year was 2003 (May 10).Most cranes finished laying eggs in early April.The earliest day was 40 days earlier than the latest one.Among the seven years,the year when the distribution range of Grus japonensis was the widest was 2000,and the cranes mainly distributed in 15 sites,such as Fulaowunpao,Jiandipao,and so on.On the contrary,they distributed only in 2 sites in 1998 and 1 site in 2003.The number and the distribution range of Grus japonensis in 2000 were far larger than those in 1997,1998 and 2003.The migratory dynamics of Grus japonensis changed with the water condition of Xianghai wetland in different years.Based on the characteristics of water eco-environment of Xianghai wetland,a strategy for protecting Grus japonensis by wisely using the flood resource was suggested.

Insect species diversity in Korean pine broad-leaved mixed forest in Changbai Mountains

JI Lanzhu, DONG Baili, WEI Chunyan, WANG Miao

2004, (9):  1527-1530. 

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The study on the insect species diversity in Changbai Mountains showed that there were 1960 insect species belonging to 26 orders,131 families and 1 162 genera,among which,881 species were pests belonging to 11 orders and 105 families,and 638 were serious ones.In forest insect communities,defoliator insect community was more divers than natural enemy community,and predatory insects were more divers than other natural enemies.The indices of annual species evenness of defoliator insect community,parasitic insect community and predatory insect community were 0.884,0.830,and 0.806,respectively,and the diversity changed with season was in the order of predatory insects>parasitic insects>defoliator insects.

Dynamics of soil fauna communities during succession process of secondary forests in Changbai Mountain

TONG Fuchun, WANG Qingli, LIU Xingshuang, XIAO Yihua

2004, (9):  1531-1535. 

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The secondary succession of forest communities in Changbai Mountian might be divided into three stages,i.e.,aggradation,transition,and steady states.The last stage will be arrived after about 100 years.At same time,the succession dynamics of various soil fauna groups were shown as:Saprophagous group was more abundant than other fauna groups,and its change trend was similar to the development of forest vegetation after disturbing;Phytophagous group had a higher amount during the prophase of forest succession,which was decreased with forest succession;the quantity of Carnivorous increased obviously after about 100-years-succession;and the composition of insect groups was that the unstable groups was more abundant when the forest was younger,but less abundant when the forest was older.

Functions of different cultivation modes in oasis agriculture on soil wind erosion control and soil moisture conservation

SU Peixi, ZHAO Aifen, DU Mingwu

2004, (9):  1536-1540. 

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During 2001～2002,the effects of different cultivation modes including winter irrigation and zero tillage,crop-grass intercropping,and early spring film mulching on sand entrainment,wind velocity gradient and soil moisture conservation were studied in the middle reaches of the Heihe River in the Hexi Corridor region.The results showed that all these modes could reduce soil wind erosion and halt sand entrainment to different degrees.Compared with the bare fields exposed by spring plowing,early spring film mulching could increase soil moisture storage by 35.6%.At present,spring plowing and sowing was a main factor responsible to the occurrence of sand storms and the increase in suspended dust content.Farmlands in the upper and middle reaches of the Heihe River generally produced a dust transport up to 4.8～6.0 million tons per year,which was higher than that of sandy desert in the same region.In the Hexi Corridor region,the suspended dust amount produced from 1 hm² farmland was equivalent to that of 1.5 hm² desert.

Mechanism analysis of optimized model of conversion from farmland to forestland in the hill-gully sub-region of Loess Plateau

LI Shidong, ZHANG Lixia

2004, (9):  1541-1546. 

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Conversion from Farmland to Forestland Program (CFF) is one of the six great ecological forest programs in China.This study covered the CFF model area of the hilly-gully sub-region of loess plateau,and introduced system dynamics and other latest theories and methodologies.Based on the analysis of five modules including that of the site observation of field stations and extensive investigations,and over 10 000 original data obtained in the fields of natural science,social science and economics,the operational mechanism of the optimized model was studied.The optimized operational models integrated maximized ecological,economic and social benefits,while sustainability concepts were proposed for typical CFF sites:The Pinus tabulaeformis+Platycladus orientalis+Zanthoxylum spp.+ Robinia pseudoacacia model at the eroded flat ridges of the middle reaches of the Yellow River.The result showed that the ecological,economic and social benefits of the optimized model reflected by main indexes were the best or better,and in the other models,either individual one was the best or others were not.From the viewpoint of comprehensive comparison of three great benefits,the optimized model was most excellent,and had eminent difference comparing to other ones through F test.The relationship between ecological and social benefit was eminent positive correlative.Social benefit was the same with economical one at some degrees.The relationship between ecological and economical benefit was more complicated.On the whole,they were positive correlative,but the economical benefit was not the greatest when the ecological one was the greatest.In general,from the viewpoint of largest comprehensive benefit,the three great benefits were not all the best,indicating that the combination of the modules must be reasonable.In order to achieve the ultimate goal of CFF,we must choose the optimized combination of ecological,economical and social benefits,and can't only pursue any one maximum of three great benefits.

Nutrient and water cycling in red soils with different planting system and their management

HE Yuanqiu, WU Dafu, LI Chengliang, WANG Xingxiang

2004, (9):  1547-1551. 

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Based on the data of long term located experiment,this paper studied the characteristics of nutrient and water cycling and balance and of energy flow in upland red soils with different planting system.The results showed that in red soil areas,the rainfall from March to June accounted for 60% of the whole year,which induced frequent seasonal drought and severe water and soil loss.The application of N,P and K on upland red soil was overabundant and unbalanced,which induced a reduced ratio of input and output.Optimized planting mode could increase the water and light utilization efficiency,decrease the frequency and degree of occurred drought,and increase the nutrient recycling rate.The main measures for rationally developing and utilizing red soil should be establishing compound agro-ecosystem model of planting and feeding,saving irrigation water,increasing mulch,cover-cultivating crops and forests,increasing the proportion of organic fertilizer,realizing rational and balanced fertilization,further optimizing planting structure,regulating energy input structure,and adopting multilevel-technologies of food chain utilization.

Soil respiration characteristics in winter wheat field in North China Plain

CHEN Shuyue, LI Jun, LU Peiling, WANG Yinghong, YU Qiang

2004, (9):  1552-1560. 

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Experiments were conducted at the Yucheng Comprehensive Experimental Station of the Chinese Academy of Sciences during 2002～2003 to investigate the respiration of a pulverous sandstone soil under cultivation of winter wheat over a growth season.The effluent CO₂ was collected and analyzed by the static-chamber/gas chromatography(GC)method at a frequency of once a week in spring and autumn,once two weeks in winter,twice a week for straw manure treatment,once a week for no straw manure treatment and nitrogen fertilization treatment in summer.The results indicated that diurnal variation of soil respiration rate showed a single peak in typical winter wheat farmlands in the North China Plain,and reached the highest at about 13 o'clock,and the lowest at about 4 o'clock in the early morning.In winter wheat growth season,the soil respiration rate was 31.23～606.85 mg·m^-2·h^-1 under straw manure,28.99～549.66 mg·m^-2·h^-1 under no straw manure,10.46～590.86 mg·m^-2·h^-1 in N₀,16.11～349.88 mg·m^-2·h^-1 in N₁₀₀,12.25～415.00 mg·m^-2·h^-1 in N ₂₀₀,and 23.01～410.58 mg·m^-2·h^-1 in N₃₀₀,showing a similar seasonal variation tendency with soil temperature.Among all treatments,the straw manure had the most distinct soil respiration,though the soil respiration also increased slightly with increasing nitrogen fertilization.Soil respiration increased exponentially with increasing soil temperature,and the correlation of soil temperature at the depth of 5 cm was the best.This relationship was usually described with the Q₁₀ model,which represented the sensitivity of soil respiration to temperature.Q₁₀ was not a fixed value,which varied with the depth at which the temperature was measured and the depth of the active soil layer and soil temperature.At same time,the Q₁₀ value decreased with increasing soil temperature.Soil water content was another important factor affecting soil respiration rate,but in this region,the relationship between soil respiration and soil moisture was poor,and no distinct rules were shown.The average net photosynthesis rate of winter wheat had a close relation with soil respiration rate.The differences between them showed that the photosynthetic uptake of CO₂ was beyond emission of soil respiration during the period from return green to mature,and the winter wheat farmland was a sink of CO₂.

Effects of fertilization on the growth,photosynthetic characteristics and yield of Coffea arabica

CAI Zhiquan, CAI Chuantao, QI Xin, YAO Tianquan

2004, (9):  1561-1564. 

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Coffea arabica is a major economic plant in agriculture plantation in tropical and subtropical areas in the world.This paper reports the experimental results on the fertilization strategy in Yunnan,China.Effects of varied levels of nitrogen (N),phosphorus (P),potassium (K) nutrients on the growth,photosynthetic characteristics and yield in three-year old saplings of C.arabica with the density of 4 500 individuals per hectare were measured.In general,N is the most important factor influencing the growth,photosynthetic capacity and yield of C.arabica,followed by K and P,respectively.The yield can be improved through spraying appropriate amount of trace elements in the leaves.The optimum matching experiments in fertilization level of N∶P₂O₅∶K₂O is at the ratio of 1∶0.5∶1.The high yield of C.arabica need high nutrient demands,but the optimum amount of fertilizer of N,P₂O₅,K₂O is 100,50,100 g per individual according to the cost-benefits analysis.The yield of C.arabica was closely related with the numbers of branch,total leaf areas and maximum rate of net photosynthesis (A_max) among different treatments.Different fertilization strategy had no significantly effects on the photochemical efficiency in dawn,but all indicators showed that the higher-fertilized plants could significantly alleviate diurnal photoinhibition.

Relationship between wheat root activity and leaf senescence

WEI Daozhi, NING Shuju, LIN Wenxiong

2004, (9):  1565-1569. 

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A field trial on the wheat root activity, chlorophyll content and photosynthetic rate showed that the decline of root activity was earlier and faster than that of flag leaf chlorophyll content and photosynthetic rate, and there was a positive correlation between root activity and leaf photosynthetic rate(r=0.8006).Topdressing nitrogen fertilizer at elongation stage could obviously improve root activity and photosynthetic rate, decrease leaf ABA con-tent, increase ZRs content and SOD activity, and delay the peak value of MDA for 8～10 days, which suggested that the variation of root activity was closely related to the senescence of flag leaf. Improving root nutrition and root activity at earlier growth stages could delay the senescence of wheatleaf.

Transformation characteristics of sulfur forms in acid sulfate soils under different soil water conditions

LIU Zhenqian, DUAN Shunshan, LI Aifen, XU Ning, WANG Jianwu, LI Minghui

2004, (9):  1570-1574. 

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Aimed to detect the quantitative impact of soil water condition on the transformation of sulfur forms in acid sulfate soils(ASS),a simulation test was made with 8 treatments.The results indicated that water was an important factor affecting the transformation processes.Wet but not inundated or over dried condition was benefit to the oxidation of pyrite S and the formation of water soluble S (WS-S) and exchangeable S (Ex-S) in ASS.In the three treatments with different inundated and drained off cycles,soil pyrite S content averagely decreased 1.29～3.20 g·kg^-1 during a single drained off period,while soil WS-S and Ex-S contents averagely increased 0.90～1.63 and 0.58～1.47 g·kg^-1,respectively.During inundated period,soil pyrite S content was relatively stable,but soil WS-S and Ex-S contents were decreased significantly due to the dilution of water.It was suggested that the total S(mainly WS-S)of ASS was discharged in drainage process,and the accumulative amount of the discharge and the transformation of the S forms were associated with the length of the inundated and drained off cycles.The dynamics of Jarosite S,organic S and element S in all treatments were also discussed here.

Evaluation efficiency of different bioassay methods on allelopathic potential of Oryza sativa

SHEN Lihua, LIANG Yiyuan, HE Huaqin, HE Jun, LIANG Kangjing, LIN Wenxiong

2004, (9):  1575-1579. 

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In this paper,three bioassay methods,i.e.,relay seeding in agar(RSA),relay seeding in silica(RSS) and seeding in rice root-exudation(SRE),were used to test the allelopathic potential of 8 rice cultivars on the target weed barnyardgrass(Echinochloa crusgalli).The results indicated that RSA was the ideal method for the bioassay,showing the highest efficiency in the evaluation of allelopathic potential.RSS and SRE had a lower efficiency than RSA,but these two methods showed the same tendency in evaluating the allelopathic potential of rice.RSA,the considered best bioassay method in this experiment,was used for 57 allelopathic rice germplasm screening,and 5 of them,i.e.,Iguape Cateto,PI312777,Azucena,Taichung Native 1 and IAC25 performed the strongest allelopathic potential in the suppression on barnyardgrass.

Interference of allelopathic rice cultivars on barnyardgrass under different water irrigation and rice plant density

XU Zhenghao, HE Yong, WANG Yiping, YU Gusong

2004, (9):  1580-1584. 

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Pot culture experiments were conducted to examine the effects of water irrigation and rice plant density on the interference of allelopathic rice on barnyardgrass (Echinochloa crus-galli).The results showed that under water irrigations,allelopathic rice cultivars Xiayitiao,Gumei 2 and Zhong 156 significantly reduced the plant height of barnyardgrass than non-allelopathic rice cultivars Xiushui 63 and Chunjiang 11.Barnyardgrass plants grew shorter as rice plant density increased.Allelopathic rice cultivars Jizaoxian and Gumei 2 interfered with barnyardgrass,even at their densities as low as 4 plants per pot,and the interference reduced plant height of barnyardgrass significantly compared with the non-rice control.Allelopathic rice cultivars Xiayitiao,Jizaoxian,PI312777,TN1,Gumei 2 and Zhong 156 at 32 rice plants per pot inhibited the growth of barnyardgrass significantly than Chunjiang 11.

Interaction between AM fungi and Rhizobium and effects of flavonoids on it

DONG Changjin, ZHAO Bin

2004, (9):  1585-1588. 

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Study showed that the biomass and nodule number of Astragalus sinicus,AM fungal infection rate,and hyphal enzyme activity of ALP and SDH were significant influenced by Rhizobium,AM fungi and flavonoids.Rh+AMF treatments had obvious differences with control in the biomass and nodule numbers of Astragalus sinicus,AM fungal infection rate and hyphal enzyme activity;and flavonoid treatments had more obvious differences with Rh+AMF treatments and control in these aspects,but no obvious differences were found in different flavonoids (apigenin and hesperitin) or in different concentrations (150 nmol·L^-1 and 1.5 μmol·L^-1) of the same flavonoid.The results showed that nodule-generation and nitrogen-fixation of Rhizobium and AM fungi infection were obvious promoted by Rhizobium and AM fungi,and this promotion effects were more significant when an appropriate amount of flavonoids was added in the Rh+AMF treatments.

Temporal and spatial variations of chemical constituents in maize

CHEN Yuxiang, ZHOU Daowei, ZHANG Yufen

2004, (9):  1589-1593. 

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Study on the temporal and spatial variations of chemical constituents in maize showed that with the development of maize,the contents of total starch,crude protein and crude lipid in its kernel increased,while those of crude protein and crude lipid in its leaf and stem decreased.The content of fiber extracted by neutral agent and that of fiber and lignin in leaves and stems increased.The crude protein content of the top leaf was higher than that of the basal leaf,while the content of fiber extracted by neutral agent and that of fiber and lignin in the top leaf were lower than those of the basal leaf.The crude protein content of the top stem was higher than that of the basal stem,while the content of the fiber extracted by neutral agent and that of the fiber and lignin in the top stem were lower than those of the basal stem.

Features of grassland resources and their classified management in Alatai region of Xinjiang

GUO Zhenggang, LIANG Tiangang, LIU Xingyuan

2004, (9):  1594-1598. 

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Grassland degradation,an important problem in grassland management,has affected the sustainable development of animal husbandry in Alatai region of Xinjiang.Based on the analysis of the community features,ecological service value and multiple functions,and main function of grassland types in the regional development,the classified management for grassland was designed.The results showed that Alatai grassland could be divided into three sectors,i.e.,ecological function region,economic function region and mixed function region.The ecological function region made up 164.66?10⁴ hm² or 16.73% of total Alatai grassland,and the grassland types included alpine meadow,alpine rangeland,swamp,mountain desert steppe,mountain steppe desert and part of plain desert.For the ecological function region,the main management strategy was to prohibit grazing and cropping.The economic function region of 116.33?10⁴ hm² accounted for 11.82% of the total Alatai grassland,the grassland types included mountain meadow,flat meadow and meadow steppe,and the main management strategy to enhance the productivity was agricultural measures,such as fertilization and irrigation.The mixed function region which included mountain steppe,plain desert steppe and most part of plain desert was 703.21?10⁴ hm² or 71.45% of total Alatai grassland,and the main management strategy was rotational grazing.

Species diversity of pasture community at different altitude levels in Qilian Mountains

CHANG Xuexiang, ZHAO Wenzhi, ZHAO Aifen

2004, (9):  1599-1603. 

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According to the occurring frequency and life form of plant species at different altitude levels,this paper studied the changing characteristics of the species α diversity of pasture community at the altitude from 2 500 m to 3 000 m in Qilian Mountains.The results showed that with increasing altitude,the Shannon-Wiener species diversity index increased from 1.432 to 1.832,and the variety of Simpson index was very complicated.An altitude of 2 701～2 800 m was an important turning point for species diversity.In pasture community of Qilian Mountains,the percentage of the poisonous and the less edible species exceeded 50%,and their biomass was more than 60% of the total biomass of the community.The biodiversity showed a degraded trend.

Soil C and N dynamics during desertification of grassland in Northern China

LIU Yingru, YANG Chi, ZHU Zhimei, LIU Meiling

2004, (9):  1604-1606. 

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This paper investigated the aboveground vegetations and the soil texture and total C and N at 75 sites of Duolun County in Xilinguole League of Inner Mongolia.The results showed that different types of vegetation community could be used to describe different stages of desertification process.During desertification,the community types were changed in the series of Leymus chinensis+Cleistogenes squarrosa → Artemisia frigida → Artemisia intramongolia → Corispermum staunyonii,Chenopodium bryoniaefolium → drift sand,and a regular change of soil clay and total C and N contents could also be found.The soil C/N ratio was increased with different stages of grassland desertification,which could be expressed in the series of 8.11→13.96→12.36→28.17.

Community features of Scarabaeoidea larvae in Stipa grandis steppe

LIU Xinmin, WU Ning

2004, (9):  1607-1610. 

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The study showed that in the Stipa grandis steppe of Inner Mongolia,there were 4 families and 9 species of Scarabaeoidea larvae,among which,the numbers of species and individuals of Melolonthidae were more than those of other families.The important value of the dominant species in Scarabaeoidea larvae community were Trematodes tenebrioides >Serica orientalis >Amphimallon solstitialis >Cyriopertha arcuata.Based on the features of their seasonal dynamics,they could be classified into three kinds.The first kind was that their density peak occurred in spring and autumn,such as Serica orientalis.Cyriopertha arcuata belonged to the second kind,and its density had no obvious fluctuation through all the year.Trematodes tenebrioides and Amphimallon solstitialis could be classified into the third kind,and their density peak all occurred in autumn.The biodiversity index of Scarabaeoidea larvae community was relatively higher in autumn than in spring and summer.Although the richness of Scarabaeoidea larvae populations was not lower in spring,their composition was very simple.

A comparative study on soil respiration between grazing and fenced typical Leymus chinensis steppe,Inner Mongolia

JIA Bingrui, ZHOU Guangsheng, WANG Fengyu, WANG Yuhui

2004, (9):  1611-1615. 

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With enclosed chamber Method,this paper studied the soil respiration in grazing and fenced typical Leymus chinensis steppes,Inner Mongolia,and its relationships with environmental factors.The results showed that the daily pattern of soil respiration could be expressed as a one-humped curve,and the highest values appeared at 13:00～15:00 in the fenced and grazing plots.The diurnal dynamics of soil respiration mainly depended on the surface temperature at the fenced plots and the soil temperature at 5 cm depth at the grazing plots.In June and July,the average soil respiration rate was 2.7 times greater at the fenced plots than that at the grazing plots,while the difference was not distinct in August and September,which was similar with the change of the belowground biomass.The reason was probably that the plant was influenced differently in different phenological phases by grazing and the change of environmental factors.It showed that human activity may not result in the increase of soil respiration rate.The seasonal dynamics of soil respiration was closely correlated with soil water content at the 0～10 cm depth at the fenced and grazing sites,and the maximum R² was 0.853 and 0.741,respectively.The difference was that the correlation of soil respiration seasonal dynamics with soil water content was larger at the fenced plots than at the grazing plots.The correlations of soil respiration diurnal and seasonal dynamics with temperature and soil water content at lower profiles were larger than those at deeper profiles at the fenced and grazing sites.

Dynamics and ecological significance of nitrogen wet-deposition in Taihu Lake region—Taking Changshu Agro-ecological Experiment Station as an example

WANG Xiaozhi, ZHU Jianguo, GAO Ren, HOSEN Yasukazu

2004, (9):  1616-1620. 

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Nitrogen wet deposition was monitored for two years (2001.6～2003.5) at the Changshu Ecological Station in Taihu Lake region.The results showed that the amount of nitrogen wet deposition had a strong seasonal pattern,with higher levels in summer and spring,and low values in autumn and winter.The proportions of NH₄^{+3-4+4+R2=0.3178 **),while the monthly NO₃-R2=0.1985 *) with monthly rainfall but positively related with the time of rainfall (R2=0.6757 ***).The NO₃-R2=0.4205 ***).The annual TN input from wet deposition was 27.0 kg·hm-2,but its concentration in each rainfall was higher than 0.2 mg·L-1 (the threshold N concentration for inland water eutrophication).The nitrogen inputted by wet deposition had an ecological significance on both nitrogen balance in agroecosystem and eutrophication.}

Sensitivity of Chlorella vulgaris to metribuzin,puma and alachlor

YANG Zhiqiang, DONG Bo, WU Jincai

2004, (9):  1621-1625. 

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The relative sensitivities of Chlorella vulgaris to three commonly used herbicides metribuzin,puma and alachlor were determined by toxicity tests of 96-h static exposures.The results showed that the toxicities of metribuzin and alachlor to C.vulgaris increased with exposure time,and the density of C.vulgaris decreased with increasing concentrations of these two herbicides in the test media.The maximum specific growth rate of C.vulgaris exposed to metribuzin (0.24 mg稬^-1) and alachlor (12.8 mg稬^-1) was 12.38% and 31.58% of the control,respectively.At low concentration,puma stimulated C.vulgaris growth,but at high concentration,it inhibited the growth significantly.The maximum specific growth rate of C.vulgaris under 0.08 mg稬^-1 puma was 111.44% of the control,and the toxicity of puma declined with increasing exposure duration.The EC₅₀ value of metribuzin,puma and alachlor was 0.021,0.937,and 5.54 mg稬^-1,respectively.The relative sensitivities of C.vulgaris to the three herbicides decreased in the order of metribuzin,puma and alachlor.The chlorophyll a content of C.vulgaris decreased with the increasing concentrations of metribuzin,puma and alachlor.

Molecular genetic diversity of phytoplankton rbcL gene in Jiaozhou Bay

LIU Yongjian, YANG Guanpin, GUAN Xiaojing

2004, (9):  1626-1632. 

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The variants of a 500 base pair fragment of RubisCo large subunit gene(rbcL)from the phytoplanktonic DNA of Jiaozhou Bay surface seawater were amplified by using polymerase chain reaction and cloned.Twenty-eight clones were randomly selected and sequenced,which were further used to determine the molecular genetic diversity of the phytoplankton of Jiaozhou Bay surface seawater.Systematic analysis showed that the clones representing cryptophyta counted for 28.6%,Stramenopiles 32.1%,Haptophyta 28.6%,Rhodophyta 3.6% and Chlorophyta 7.1%.The sequences from Cryptophyta,Stramenopiles,Haptophyta and Rhodophyta belonged to type D of Form I rbcL and Chlorophyta to type B,indicating that the dominant phytoplankton were those represented by type D rbcL.The genetic diversity index and the reversely translated amino acid sequence diversity of Jiaozhou Bay phytoplankton were 2.85 and 0.20,which were determined by the abundances of operational taxonomy units and the reversely translated amino acid sequences respectively.

A primary study on antimicrobial and cytotoxic activity of marine bacteria

ZHENG Li, LIN Wei, YAN Xiaojun, CHEN Haimin

2004, (9):  1633-1636. 

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Marine bacteria were isolated from marine organisms including invertebrates and seaweeds and from sea water and sediments of different sea area.Ethyl acetate extractions of marine bacterial fermentation were screened for antimicrobial and cytotoxicity activities by using the methods of agar diffusion and MTT assay,and the relationship of active bacteria and their origin was studied.The results showed that 42 strains among total 341 isolated marine bacteria had antimicrobial activity,and 7 strains had cytotoxicity activity.The proportion of active bacteria associated with marine invertebrates and seaweeds (22% and 11%) was higher than that isolated from sea water and sediments (7% and 5%).The most active marine bacteria were assigned to the Pseudomonas,Photobacterium,Clostridium,Alteromonas and Flavobacterium group.

Effects of environmental factors on catch variation of main species of stow net fisheries in East China Sea

ZHOU Sufang, FAN Wei, CUI Xuesen, CHENG Yanhong

2004, (9):  1637-1640. 

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Stow net fishery is one of the important fishing methods in the East China Sea.This paper used the generalized additive models (GAMs) to quantitatively describe the relationships between stow net catch and environmental factors (sea surface temperature SST,water depth,fishing position and tide) in the East China Sea.The results indicated that each factor had its own nonlinear effect on the catch per unit effort (CPUE) of haitail (Trichiurus japonicus),small yellow croaker (Larimichthys polyactis) and butter fish (Pampus spp.),and SST and water depth were the key factors.The GAMs' fitting results showed that SST had the strongest effect on the catch per unit effort of haitail,and water depth had the second one.The effects of fishing location and tide were very small.Water depth was the most influential variable when adjusted for the effects on small yellow croaker.SST,fishing location and tide had similar effects.Meanwhile,water depth and SST were the key factors affecting the catch per unit effort of butter fish.They had similar intensity.

Plant physiological and molecular biological mechanism in response to aluminium toxicity

LIU Qiang, ZHENG Shaojian, LIN Xianyong

2004, (9):  1641-1649. 

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Aluminium toxicity is the major factor limiting crop growth on acid soils,which greatly affects the crop productivity on about 40% cultivated soils of the world and 21% of China.In the past decades,a lot of researches on aluminium toxicity and resistant mechanisms have been doing,and great progress was achieved.This paper dealt with the genetic differences in aluminium tolerance among plants,screening and selecting methods and technologies for identifying aluminium resistance in plants,and physiological and molecular mechanism resistance to aluminium toxicity.Some aspects needed to be further studied were also briefly discussed.

Recent advances in research and application of associated nitrogen-fixation with graminaceous plants

ZHANG Limei, FANG Ping, ZHU Riqing

2004, (9):  1650-1654. 

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The category, characteristic of diazotrophs isolated from inside and/or rhizosphere of graminaceous plants in recent year and the mechanism of the promoting effects on their host plant were reviewed in this paper. The current status of application of associative nitrogen-fixation inoculants and the problems in inoculation were discussed. It was indicated that the main factors influencing the effects of inoculants include the competition of indigenous micro-organism with inoculants for nutritions and energy, difference of host plant genotypes in associative relationship, and variance of environmental conditions such as the concentration of ammonium in soil solution and the oxygen partial pressure in soil air. The trends of future research in this field were prospected, for example, to isolate and identify the high nitrogen fixing efficiency strains with wider environmental adaptability, to create associative nitrogen fixing bacteria strain which is able to bear or endure higher concentration of ammonium by gene engineering technique, to induce graminaceous plant forming root nodule for nitrogen fixation and to exert the predominance of endophytic diazotrophs.

A review on research of implement application for crop simulation model in regional scale by using remote sensing technology

MA Yuping, WANG Shili

2004, (9):  1655-1661. 

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When applying crop simulation model developed from plot-scale level to regional scale,some challenges such as acquirement of some broader spatial data and regionalization of parameters will arise,while satellite can monitor crop growth status by remote sensing.Therefore,regional application of crop simulation model will be implement by remote sensing technique.In this paper,some research advances are reviewed,which include the methods of biophysical parameters retrieved from remote sensing data for crop model,the approach of biomass obtained by remote sensing data directly,and the means of matching temporal and spatial resolution between remote sensing data and crop model input.Three solutions (forcing,recalibration and validation) to the application of crop model in region scale by using remote sensing technique were emphasized,and the current problem and future research orientation in this filed were discussed in brief.

Function of artificial grassland in restoration of degraded natural grassland and its research advance

NIU Shuli, JIANG Gaoming

2004, (9):  1662-1666. 

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This paper analyzed the degradation actuality of natural grassland,its reasons and corresponding restoration ways.Natural restoration is the easiest way,but it is very slow.The establishment of some artificial grassland is the most effective way to lessen the oppressiveness of natural grassland.The research advances on artificial grassland were summarized,and the ways for promoting the sustainable development of pasturing area were suggested.Considering the high productivity,planting forage maize may be an available attempt in Hunshandak Sandland.

Relationship between vegetable nutrition and nitrate content

LI Huihe, WANG Zhengyin, LI Baozhen

2004, (9):  1667-1672. 

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Nitrate accumulation in vegetables,which related well to vegetable nutrition,becomes one of the limiting factors of non-pollution vegetables production.Preference to nitrate is the nutritional characteristic of vegetables.Nitrate is absorbed by vegetables through high-affinity transport system(HATS)and low-affinity transport system(LATS),and is reduced and transformed under the effect of such essential elements as molybdenum,manganese,iron,copper,sulphur and phosphorus.In this paper,the effects of essential elements on nitrate absorption and reductive transform were reviewed,and the relationships of nitrate accumulation in vegetables with vegetable nutrition of nitrogen,phosphorus,potassium and mid-and microelements as well as with balanced fertilization were discussed.The research keys in the field were prospected for controlling nitrate accumulation,improving vegetables' quality and producing non-pollution vegetables.

Application of plant polyphenols in environmental protection and agricultural production

FU Meiyun, ZHOU Lixiang

2004, (9):  1673-1677. 

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Plant polyphenols,the secondary metabolites in plant,contain many phenol-hydroxyl groups.They can bind with protein,alkaloids and polysaccharides,and consequently,exhibit an astringent property.Plant polyphenols can also bind with metal ions to form polyphenol-metal complexes,which are probably soluble or precipitated,depending on the type of plant polyphenols.Up to now,about 600 plant polyphenols have been found.Plant polyphenols can be applied widely in environmental pollution control and agriculture production.

Spatial variability and quantitative analysis of field factors based on GIS

CHEN Rongrong, ZHOU Zhiguo, CAO Weixing, DAI Tingbo

2004, (9):  1678-1680. 

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The objective of this research was to investigate the variability and the quantitative relationships among soil nutrients and crop growth status and yield.All data were analyzed by both classical statistics and geostatistics based on GIS.Soil properties included soil pH,total N,organic matter,available P and available K,while crop growth status was indicated by SPAD,LAI and SPAD譒AI.All parameters except soil pH exhibited spatial correlation.Soil total N and organic matter,SPAD,LAI and SPAD譒AI were all correlated to rice yield.Kriged interpolation maps provided good indication of the spatial variability in crop yield and growth status.Spatial interpolation and correlation analysis proved that SPAD譒AI was more indicative of crop growth status than individual variables,and useful for implementing growth season and topdressing as needed.

Effect of acid rain on mercury leaching from forest yellow soil in Jinyun Mountain

LI Jing, WEI Shiqiang, YANG Xuechun

2004, (9):  1681-1683. 

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Forest yellow soil and arable yellow soil in Jinyun Mountain were collected to study the effect of simulated acid rain(adjusted to pH 2.0,3.0,4.0 and 5.0) on the Hg leaching from soils by the methods of static extraction and dynamic leaching.The results showed that in forest yellow soils,surface accumulation of Hg occurred,and the accumulated Hg was easier to be leached out than that in arable yellow soil by acid rain.The amount of leached Hg was the largest at pH 4.0.To abate the risk of Hg pollution in water bodies by the Hg leaching from this forest soil,the Mountain should be closed,and timber-felling should be forbidden.

Rapid measurements of CO₂ flux density and water use efficiency of crop community

ZHU Zhilin, SUN Xiaomin, ZHANG Renhua, SU Hongbo, TANG Xinzai

2004, (9):  1684-1686. 

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In this paper,Eddy Correlation (EC) method was employed to measure the latent heat and CO₂ flux density and to calculate Water Use Efficiency (WUE) of winter wheat community in Yucheng district,Shandong Province in 1997.The results showed that the CO₂ flux density had an obvious diurnal change,with a maximum about1.5 mg·s^-1·m^-2,which appeared at about 9:00～10:00 am in general.The WUE of wheat community presented a fall trend from morning to afternoon,and the CO₂ flux density and WUE also had an obvious seasonal change,being lower in the early and late growth stages,and higher in the middle growth stage.The ranges of daily mean CO₂ flux density and WUE were 0.2～0.9 mg·s^-1·m^-2 and 5～20 gCO₂·kg^-1 H₂O,respectively.

Bioassay on oviposition repellency of non-preferable plant extracts against citrus red mite Panonychus citri

CEN Yijing, PANG Xiongfei, ZHOU Qiong, PENG Yuefeng, XU Changbao

2004, (9):  1687-1690. 

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The oviposition repellency of the alcohol extracts from 50 species of non-preferable plants and azadirachtin against citrus red mite (Panonychus citri) was determined using laboratory bioassays.In choice tests,the extracts from 42 of the 50 plant species and 1% azadirachtin (2000@) significantly reduced oviposition 1d after treatment.The repellency effect of the extracts from the 42 plant species was better than that of azadirachtin.Mikania micrantha extract had the best result,with an Interference Index of Population Control (IIPC) of 0.087 1 d after treatment,and significantly reduced oviposition for 9 d,while the extracts from Sesbania cannabina,Allium tuberosum,Paederia scandens,Duranta erecta and Dicranopteris pedata also had good effects,with an oviposition repellency of over 70% 1 d after treatment,and significantly reduced oviposition for 4～6 d.The effect became weaker as time went on.None of the extracts showed significant oviposition attraction.