Table of Content

15 November 2005, Volume 16 Issue 11

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Field investigation on Salix psammophila plant morphology and airflow structure

WANG Lei, WANG Zhi, LIU Lianyou, HA Si

2005, 16(11):  2007-2011. 

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A field investigation in the flat sands of southern Maowusu sandy land showed that artificially cultivated single line Salix psammophila could accumulate sand because the plant decreased the windward and leeward wind velocity.There was a significant correlation(R=0.696) between accumulated sand volume(V₂)and plant volume(V₁).When the wind velocity at 4 m height of single-line S.psammophila was 6 m·s^-1,the wind velocity decreased at 3H windward,increased at 2H windward,and then steeply decreased leeward,reached the lowest value at 1H leeward and gradually recovered to the open field velocity.The protection distance of single-line S.psammophila was about 17 H′,and the effective protection distance was about 13 H′.Single-line S.psammophila had little effect on the wind velocity above plant height.

Physicomechanical properties of plantation poplar wood under different eco-environments

ZHA Chaosheng, WANG Jianan, FANG Yu, LIU Shengquan

2005, 16(11):  2012-2018. 

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The measurement of the physicomechanical properties of 9 plantation poplar I-69(Populus deltoides CV.I-69/55)woods under fertilization and seasonal flooding showed that compared with no fertilization,fertilization increased the ring width,static modulus of elasticity,and compressive strength parallel to the grain by 0.99%(P>0.05),2.73%(P<0.05)and 1.06%(P<0.05),while decreased the air-dry radial,tangential,volumetric shrinkage,oven-dry radial,tangential,volumetric shrinkage,basic density,MOR,and dynamic modulus of elasticity by 4.2%,7.7%,6.6%,15.6%,6.3%,11.1%,2%,1.79% and 8.13%,respectively.Seasonal flooding decreased the basic density,air-dry radial,tangential,volumetric shrinkage,oven-dry radial,tangential,volumetric shrinkage,MOR,MOE,and compressive strength parallel to the grain by 5.5%,11.1%,9.2%,9.6%,16.7%,10.9%,8.5%,24.29%,18.18% and 16.81%,respectively,in comparing with non-flooding.

Interspecific association between understory species in a southern highland plantation

HU Lile, YAN Boqian, LIU Qijing, ZHU Jiaojun

2005, 16(11):  2019-2024. 

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Based upon 2×2 contingency table,χ² test and association coefficient were used to determine the interspecific association between understory species in a southern highland plantation,and to analyze the restoration degree and the stability of southern highland vegetations originated from plantation.The Qianyanzhou in Taihe County of Jiangxi Province,a typical sample of southern highland plantation,was chosen to make the study.The results showed that both in shrub layer and in herb layer,species pair with χ² reaching significant level(P<0.05) was few in number.In shrub layer,12 species pairs' association was highly significant(P<0.01),19 pairs'was significant(P<0.05),and other 200 pairs'was nonsignificant,while in herb layer,11 pairs'was highly significant,11 pairs' was significant and other 83 pairs'was nonsignificant.According to interspecific association and correlation,shrub layer was divided into two species groups:GroupⅠ.Adinandra bockiana,Syzygium grijsii,Vaccinium bracteatum,Ilex aculeolata,Smilax ferox,Eurya muricata and GroupⅡ.Lespedeza davidii,Serissa serissoides,Vitex negundo var.cannabifolia.Many species in GroupⅠhad a significantly negative association with the species in GroupⅡ,and dominant species always played a key role in the relationships among species.The three dominant species in herb layer,Woodwardia japonica,Dryopteris atrata and Adiantum flabellulatum,had a highly significant positive correlation between each other,and moreover,had a significant or highly significant positive association with many other herbaceous species.Similarily,dominant species in shrub layer played a key role on the interspecific association in the two species groups.The ratios of positive and negative association indicating the species compositions of the two layers were fluctuating,which was 125/106 in shrub layer and 42/63 in herb layer.Several shortcomings of interspecific association method were pointed out,with some proposals put forward.

Natural vegetation restoration and soil nutrient dynamics of abandoned farmlands in forest-steppe zone on Loess Plateau

WEN Zhongming, JIAO Feng, LIU Baoyuan, BU Yaojun, JIAO Juying

2005, 16(11):  2025-2029. 

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To understand the relationship between plant community succession and soil nutrient dynamics is crucial in intervening vegetation succession.This paper reported the results from a study carried out in a forest-steppe zone on the Loess Plateau,with emphasis on the vegetation characteristics and soil nutrient dynamics during vegetation restoration on abandoned farmlands of this area.The results showed that under zonal habitat conditions,natural vegetation succession would turn toward the original vegetation communities,but the expected shrub or trees communities didn't occur after 40～50 years,and Stipa bungeana,Artemisia sacrorum,Bothriochloa ischaemun,Stipa grandis and Lespedeza davurica communities were still the widely distributed communities.Vegetation restoration had a significant effect on soil nutrient dynamics.In general,soil nutrient contents increased with restoration time,and extremely significant changes occurred in soil organic matter,total N,available N,and available K(P<0.001),while only significant changes in available P(0.05<P<0.01) and no significant change in total P(P>0.05).Moreover,the changes were also found in soil profile.Statistical analysis showed that from surface layer(0～20 cm)to deeper layer(to 60 cm),extremely significant changes occurred in soil organic matter,total N,available N,available K and available P(P<0.001),and significant change in total P(P<0.05).Soil nutrients intended to accumulate in surface layer.Further linear correlation analysis showed that soil organic matter,total N,available N and available K were significantly correlated each other(P<0.001),but didn't show correlation with soil total P and available P.

Decomposition of Triploid populus tomentosa fine root and Lolium multiflorum grass root in a composite ecosystem and their nutrient dynamics

FAN Bing, LI Xianwei, ZHANG Jian, CHEN Wende, DONG Huixia

2005, 16(11):  2030-2034. 

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This paper studied the root decomposition and its nutrient dynamics of Triploid populus tomentosa and Lolium multiflorum in a plantation converted from farmland at Tianquan County of Sichuan Province.The results showed that the weight loss rate of fine root and grass root showed an exponential relationship with time,with an annual loss of 76.17%,69.80%,73.44% and 79.53% for fine roots of 0～1,1～2 and 0～2 mm in diameter and grass root,respectively.During the decomposition of fine roots,their N and Ca contents increased,while P,K and Mg contents were in adverse.The nutrient contents of grass root during its decomposition had an irregular variation.The remaining percentage of fine root P,K and Mg had the same trend as root weight loss during its decomposition,while that of N and Ca had a slight decrease.For grass root,its N,P,K,Ca and Mg contents declined rapidly at the initial stage of decomposition,and then decreased slowly with irregular deposition rate.

Transpiration of Choerospondias axillaris in agro-forestrial system and its affecting factors

ZHAO Ying, ZHANG Bin, ZHAO Huachun, WANG Mingzhu

2005, 16(11):  2035-2040. 

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Measurement of transpiration is essential to assess plant water use efficiency.Applying Grainer method,this paper measured the sap flow of Choerospondias axillaries in an agro-forestrial system,aimed to evaluate the effects of intercropping and pruning on the diurnal variation of transpiration,and to relate the transpiration rate with climatic factors.The results showed that the diurnal variation of Choerospondias axillaries transpiration rate appeared in parabola,low in the morning and evening,and high at noon.The transpiration rate was closely related to leaf stomatal conductivity and soil water potential,especially the water potential in 100 cm soil depth(R=0.737^**).The transpiration rate of Choerospondias axillaries was increased by about 40%～160% in agro-forestrial system through the changes in regional environment and in the deep soil water use by tree.Correlation analysis and multi-factor successive regression analysis indicated that the transpiration was controlled by ray radiation intensity,air temperature and ground temperature,followed by the difference between saturated and actual vapor pressure and the wind speed.A statistical model for calculating the sap flow rate by micrometeorological factors was also provided.

Dynamics of soil properties under secondary succession forest communities in MtJinyun

LIU Hongyan, HUANG Jianguo

2005, 16(11):  2041-2046. 

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Mt.Jinyun is located in the north suburb of Chongqing,30 km away from the city center.It is rich in forest plants,an epitome of forests in north tropical areas of China.Under anthropocentric disturbance,there still exist large numbers of succession communities,and the process of successive development follows the way of shrub-grassland(X₁)→coniferous forest(X₂)→coniferous-broad leaved mixed forest(X₃)→evergreen broad-leaved forest(X₄).By now,soil and water conservation is very important in the Three Gorges area of Yangtze River,and the investigation on the secondary succession of the forests could help to realize the changes of the forests and soils under anthropocentric disturbance,and supply information on the protection of natural forests and the artificial reforestation of this area.In this paper,some typical and representative plant communities in different succession stages were selected to study the plant composition and type and the soil properties,with species diversity indices and canopy density investigated in many standard squares and soil physical and chemical characteristics analyzed.The results showed that there were obvious variations of soil properties with time.As the plant community developed from primary stage to climax,the contents of soil organic matter,total N,and available N and K increased in order of X₁<X₂<X₃<X₄,soil pH changed from 5.23(X₁)to 4.06(X₄),soil base saturation varied from 58.3%(X₁)to 37.7%(X₄),and soil CEC increased with the succession.It was suggested that an intense soil acid leaching was occurred in Mt.Jinyun.The contents of soil organic matter and total N in different layers showed a trend of A>B>C,e.g.,soil total nitrogen in evergreen broad leaved forest was 2.31(A),0.66(B)and 0.12(C)g·kg^-1.Gray analysis was used to study the relationships of soil properties between the climax community and other three succession communities.The relation coefficient was 0.461 0(X₃),0.586 2(X₂)and 0.6821(X₁),respectively,indicating that soil nutrients were accumulated as the forest succession community progressed.The plant arbor species followed the sequence of 0(X₁)<7.5(X₂)<9.0(X₃)<12.8(X₄),and the canopy density ranked as the same way.Plant community could affect soil nutrient reserves significantly.Multivariate variance analysis showed that soil properties varied significantly among different seasons,but this variation had no impact on the community replacement and soil development during the chronosequence of community succession.The variation of soil properties adapted well to each successive community.

Construction of information management-based virtual forest landscape and its application

CHEN Chongcheng, TANG Liyu, QUAN Bing, LI Jianwei, SHI Song

2005, 16(11):  2047-2052. 

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Based on the analysis of the contents and technical characteristics of different scale forest visualization modeling,this paper brought forward the principles and technical systems of constructing an information management-based virtual forest landscape.With the combination of process modeling and tree geometric structure description,a software method of interactively and parameterized tree modeling was developed,and the corresponding renderings and geometrical elements simplification algorithms were delineated to speed up rendering run-timely.As a pilot study,the geometrical model bases associated with the typical tree categories in Zhangpu County of Fujian Province,southeast China were established as template files.A Virtual Forest Management System prototype was developed with GIS component(ArcObject),OpenGL graphics environment,and Visual C⁺⁺ language,based on forest inventory and remote sensing data.The prototype could be used for roaming between 2D and 3D,information query and analysis,and virtual and interactive forest growth simulation,and its reality and accuracy could meet the needs of forest resource management.Some typical interfaces of the system and the illustrative scene cross-sections of simulated masson pine growth under conditions of competition and thinning were listed.

Spatial variance characters of urban synthesis pattern indices at different scales

YUE Wenze, XU Jianhua, XU Lihua, TAN Wenqi, MEI Anxin

2005, 16(11):  2053-2059. 

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Scale holds the key to understand pattern-process interactions,and indeed,becomes one of the corner-stone concepts in landscape ecology.Geographic Information System and remote sensing techniques provide an effective tool to characterize the spatial pattern and spatial heterogeneity at different scales.As an example,these techniques are applied to analyze the urban landscape diversity index,contagion index and fractal dimension on the SPOT remote sensing images at four scales.This paper modeled the semivariogram of these three landscape indices at different scales,and the results indicated that the spatial variance characters of diversity index,contagion index and fractal dimension were similar at different scales,which was spatial dependence.The spatial dependence was showed at each scale,the smaller the scale,the stronger the spatial dependence.With the scale reduced,more details of spatial variance were discovered.The contribution of spatial autocorrelation of these three indices to total spatial variance increased gradually,but when the scale was quite small,spatial variance analysis would destroy the interior structure of landscape system.The semivariogram models of different landscape indices were very different at the same scale,illuminating that these models were incomparable at different scales.According to above analyses and based on the study of urban land use structure,1 km extent was the more perfect scale for studying the spatial variance of urban landscape pattern in Shanghai.The spatial variance of landscape indices had the character of scale-dependence,and was a function of scale.The results differed at different scales we chose,and thus,the influence of scales on pattern could not be neglected in the research of landscape ecology.The changes of these three landscape indices displayed the regularity of urban spatial structure at different scales,i.e.,they were complicated and no regularity at small scale,polycentric at moderate scale,and circle-zoning at big scale.

Impact of urbanization on pedodiversity in Suzhou area

SUN Yanci, ZHANG Xuelei, CHEN Jie

2005, 16(11):  2060-2065. 

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Based on the TM remote sensing information of 1984,1995,2000 and 2003,this paper quantitatively analyzed the spatial-temporal dynamic changes of pedodiversity in Suzhou area under quickly growing urbanization.The results showed that in this area,clay loamy typic-hapli-stagnic anthrosol and fine sand clay loamy typic-hapli-stagnic anthrosol were the predominant soil types,but their distribution area decreased 5.11% and 3.14%,respectively,in latest 20 years.Jinchang,Pingjiang and Canglang Districts were the focuses of urbanization in Suzhou area,where pedodiversity changed furiously.During 1984～2003,more than 90% of the clay loamy typic-hapli-stagni gleyosol in Pingjiang District and sandy calcaric-mottlic-udi-orthic primosol in Taicang City were almost disappeared,and changed into residential area.Statistical analysis showed that urbanization had a significant impact on pedodiversity,and was the prime driving force on the pedodiversity in Suzhou area.

Spatial-temporal dynamics of landscape fragmentation in North Shannxi Loess Plateau

LI Zhengguo, WANG Yanglin, ZHANG Xiaofei, WU Jiansheng

2005, 16(11):  2066-2070. 

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The study of landscape fragmentation is an important means to reveal regional ecological processes.By using the remote sensing data of 1987,1997 and 2002,and the GIS tools,some representative quantitative indices of the landscape spatial structure and landscape fragmentation in North Shannxi Loess Plateau were calculated,aimed to investigate the relationships between landscape ecological structure and landscape pattern in this area.The results showed that cropland contributed most to the extent of landscape fragmentation,but unused land lacked obvious relationship with it.To get large-area images accurately and promptly is very important for monitoring ecological process in regional scale.Moderate-Resolution Imaging Spectroradiometer(MODIS) images in 2003 were used to derive monthly landscape fragmentation information calculated with Local Index of Spatial Associations(LISA) based on Spatial Statistical Analysis(SSA).The analysis of the fragmented landscape types showed that human disturbance had a main contribution to the seasonal landscape fragmentation.Furthermore,with the increasing percentages of cropland and unused land,landscape became more fragmented,while forestland coverage had inverse effects on the fragmentation.

Effects of N fertilization on winter wheat grain yield and its crude protein content and apparent N losses

CUI Zhenling, SHI Liwei, XU Jiufei, LI Junliang, ZHANG Fusuo, CHEN Xinping

2005, 16(11):  2071-2075. 

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Field experiments were conducted at four sites in 2002 to study the effects of N fertilization on winter wheat yield and its crude protein content and apparent N losses.The results showed that at these sites,the N application rate for maximum grain yield was 0,0,79 and 118 kg·hm^-2,and that for maximum grain crude protein content was 122,100,127 and 174 kg·hm^-2,respectively.The residual nitrate-N content in 0～90 cm soil layer after harvest was linearly increased,while the apparent N losses during wheat growth season was exponentially increased with increasing N application rate.Under the N application rate for maximum yield,soil residual nitrate-N content ranged from 86 to 115 kg·hm^-2 and apparent N losses ranged from² to 32 kg·hm^-2,which were much lower than the residual nitrate-N content(106～168 kg·hm^-2)and apparent N losses(14～56 kg·hm^-2)when the maximum grain crude protein content was achieved.The results showed that the maximum wheat grain yield and the environment effects of N fertilization could be harmonized by an optimized N application rate,but,if considering the importance of wheat grain protein,more research in the future should be needed.

Dynamics of soil enzyme activity and nutrient content in intercropped cotton rhizosphere and non-rhizosphere

MENG Yali, WANG Liguo, ZHOU Zhiguo, WANG Ying, ZHANG Lizhen, BIAN Haiyun, ZHANG Siping, CHEN Binglin

2005, 16(11):  2076-2080. 

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The study with high yield cotton-wheat double cropping system showed that soil urease,invertase,protease and catalase activities in intercropped cotton field had the same changing trends with those in mono-cultured cotton field,but were significantly higher in intercropped than in mono-cultured cotton rhizosphere and non-rhizosphere at all development stages of cotton.During the intergrowth period of wheat and cotton,soil nutrient contents in intercropped cotton rhizosphere and non-rhizosphere were lower than or had little difference with those in mono-cultured cotton rhizosphere and non-rhizosphere,but became significantly higher after wheat harvested.The changing trends of soil nutrient contents in intercropped cotton field had little difference from those in mono-cultured cotton field,but the nutrient absorption peak appeared late.The soil enzyme activities and nutrient contents were generally higher in rhizosphere than in non-rhizosphere of both intercropped and mono-cultured cotton.Soil nutrient contents had significant(P<0.05,n=32) or very significant(P<0.01,n=32) correlation with the activities of soil urease,invertase and protease,but had little correlation with soil catalase activity.

Distribution of C and N in different particle fractions of meadow brown soil in lower reach of Liaohe River Plain

PANG Xiangfeng, YU Wantai, SU Zhuang, ZHANG Lu, MA Qiang

2005, 16(11):  2081-2085. 

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The study of meadow brown soil with different reclamation history in the lower reach of Liaohe River Plain showed that in 0～20 and 20～40 cm soil layers,<0.002 mm fraction had the highest content of organic carbon,followed by <0.02 and <0.2 mm fractions.The distribution pattern of total nitrogen was similar to that of organic carbon.There was no obvious correlation between the distribution of organic carbon and total nitrogen in different soil particle fractions and the history of reclamation,but the correlation between organic carbon and total nitrogen in different soil particle fractions was highly significant,with the correlation coefficients 0.74,0.94 and 0.91 in fractions<0.2,<0.02 and<0.002 mm,respectively.

Spatial variability of soil phosphorus in field scale

JIANG Yong, LIANG Wenju, ZHANG Yuge

2005, 16(11):  2086-2091. 

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In this paper,the spatial variability of soil total P and Olsen-P at the depths of 0～10 and 10～20 cm in a field-scale was examined by using traditional statistics combined with geostatistics methods.A sampling grid of 30 m×42 m including 49 pairs of soil sampling points was established in the Shenyang Experimental Station of Ecology,Chinese Academy of Sciences.The results showed that the variance coefficients were much higher for Olsen-P(46.56%～56.42%)than for total P(11.68%～13.33%).Both total P and Olsen-P in the two soil depths had strongly spatial structures and similar spatial correlation ranges.The parameters derived from best-fitted models showed that the spatial variability of both total P and Olsen-P was mainly affected by structural factors,with C/(C₀+C)being higher than 66% for all the variables.The kriging contour maps showed that both total P and Olsen-P in the two soil depths had similar spatial distribution patterns.A more precise sampling scheme could be made based on the spatial distribution pattern of test soil properties combined with traditional variance coefficients.To recognize the strong variability of soil Olsen-P in field-scale is of significance for better understanding the P cycling in farm ecosystems and for precise agriculture.

Main affecting factors of soil wind erosion under different land use patterns—A case study in Wuchuan County,Inner Mongolia

HE Wenqing, ZHAO Caixia, GAO Wangsheng, CHEN Yuanquan, QIN Hongling, FAN Xiurong

2005, 16(11):  2092-2096. 

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Field investigation,laboratory analysis and wind tunnel simulation showed that in Wuchuan County of Inner Mongolia,low precipitation,frequent and high wind velocity,coarse soil texture,and thawing and freezing were the main causes of soil wind erosion happened very easily in spring.In late winter and early spring,the vegetation coverage was in order of shrub-land>natural grassland>rainfed farmland,and thus,increasing the surface cover of rainfed farmland should be an urgent need to control the wind erosion in Wuchuan County.The soil wind erosion rate decreased exponentially with increasing soil moisture content,and 6% soil moisture content was a turning point from severe to light.The topsoil moisture content under different land use patterns was in order of natural grassland> rainfed farmland >shrub-land.With increasing wind velocity,soil wind erosion rate increased by power function,and 18 m穝^-1 wind velocity was a switching point to aggravate the wind erosion.

Effects of rhizosphere CO₂ concentration on potato growth

SUN Zhouping, LI Tianlai, FAN Wenli

2005, 16(11):  2097-2101. 

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With the method of areoponics,this paper established a rhizosphere gas environment research system to study the effects of different rhizosphere CO₂ concentration on the growth of potato(Solanum tuberosum)plants.The results showed that in treatments 380 and 380～920 μmol CO₂·mol^-1,the plant height,stem diameter,leaf area,root length,and individuals of stolon and mini-tuber had a similar variation trend with time,and presented two distinct phases.The plants grew vigorously,and their tuber yield increased markedly,compared with treatment 3 600 μmol CO₂·mol^-1,which indicated that 380～920 μmol CO₂·mol^-1 was the appropriate CO₂ concentration in the root zone to promote potato growth,while overmuch rhizosphere CO₂ would markedly inhibit the growth and development of potato plants.Treatment 3 600 μmol CO₂·mol^-1 and sand culture had the similar stem diameter,leaf area,and individuals of stolon and mini-tuber.The plants grew short and weak,and tuber yield was lower.

Quantitative analysis on the relationships between cotton fiber quality and meteorological factors

MA Fuyu, CAO Weixing, LI Shaokun, ZHU Yan, ZHOU Zhiguo, ZHENG Zhong, YANG Jianrong

2005, 16(11):  2102-2107. 

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With the method of planting cotton by stages at the sites from Yangtze valley to north Xinjiang,this paper studied the effects of air temperature and sunlight on cotton fiber quality in 2002～2003.The results showed that with increasing latitude,fiber length increased,while micronaire value and soluble sugar content(SSC) decreased.An ecological model describing the relationships of fiber strength,micronaire value and SSC with air temperature and sunlight was built to determine the optimal range and critical value of air temperature during boll development period.If a high quality fiber(length≥27 mm) was targeted,the daily mean temperature(DMT) and minimum temperature(Tmin) during this period should be 21.3～29.7 and 10.7～21.3 ℃,respectively,and the daily temperature difference(DTD) should not be >15.2 ℃.Fiber length was the longest when the DMT was 25.4 ℃.If the lowest fiber length was ≥25 mm,DMT and Tmin should not be lower than 15.5 and 10.7 ℃,respectively,and DTD should not be over 17.9 ℃ during boll development period.

Analysis on the role and endowment of virtual water in agricultural ecosystem

LIU Wenhua, DONG Rencai, DENG Hongbing

2005, 16(11):  2108-2111. 

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Water is one of the most important components of agricultural ecosystem,and also a source of food security,which plays an essential role in ensuring sustainable food resources for a growing population.In this study,the policy relevancy of virtual water was addressed,with food production,alternative trend of import,and product condition analyzed.The results showed that an average of 10.2?10⁹ m³ water and 27.7?10⁶ hm² land was transferred by imported wheat,while an average of 0.3?10⁹ m³ water and 1.6?10⁶ hm² land was transferred by imported maize.The sum of virtual water equivalent was 10.5?10⁹ m³.It's of significance to alleviate the pressure of water stress in agriculture and arable land,help to resolve water predication of food production by food imports,and compensate water endowment.

Root growth characteristics of soybean and faba bean at their seedling stage

CHEN Yang, LI Long, ZHANG Fusuo

2005, 16(11):  2112-2116. 

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Soybean and faba bean are the two main legumes widely intercropped with cereals(e.g.,wheat or maize) in western China,but have significantly different performance in intercropping system.Compared to soybean,faba bean has a stronger competitive ability.Considering that underground interspecific interaction makes a significant contribution to the advantage of intercropping system,a pot experiment was conducted to compare the differences in root growth and morphological parameters between soybean and faba bean at their seedling stage.A PVC tube,with 10 cm in diameter and 50 cm in depth,was filled with quartz and used to grow the crops.Root systems were scanned by a scanner,and analyzed by WinRHIZO on days 14,21,28,35 and 42 after seedling emergence.The results indicated that on the 42nd day after seedling emergence,the root surface area of faba bean was 2.61 times larger than that of soybean.Soybean roots distributed in the whole layer of quartz on the 14th day,but most faba bean roots only distributed in its top layer.Soybean roots were thinner,and most of them were 0.25～1.0 mm in diameter,while faba bean roots were thicker,and their diameter was mostly between 0.5～1.5 mm.All of these facts resulted in a higher absorption capacity and nutrient use efficiency of faba bean,which could be one of the reasons that faba bean had a stronger competitive capacity than soybean.

Effects of weak light and high temperature stress after anthesis on flag leaf chlorophyll fluorescence and grain fill of wheat

LIU Xia, YIN Yanping, JIANG Chunming, HE Mingrong, WANG Zhenlin

2005, 16(11):  2117-2121. 

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A field experiment with wheat showed that after anthesis,the photosystemⅡ(PSⅡ),photochemical efficiency(F_v/F_m) and photosynthetic rate(P_n) of flag leaf decreased substantially,its actual quantum yield of PSⅡ electron transport(ΦPSⅡ) and photochemical quenching co-efficient(qP) declined slightly,while its non-photochemical quenching(NPQ) increased slightly three days after shading,compared with the control.Three days after high temperature treatment,the F_v/F_m、P_n、ФPSⅡand qP decreased significantly,while the NPQ increased slightly.During the course of recovery after the stresses,the parameters fluorescence and P_n which were stressed by shading and high temperature at prophase recovered slightly,while those stressed at metaphase decreased all along,indicating that the damage at prophase was reversible,but the stress at metaphase accelerated the caducity of flag leaves.The grain-filling processes of different treatments were modeled with Logistic equation,which showed that the decline of per kernel weight was mainly caused by the decrease of mean filling rate,maximal filling rate,and slowincrease period filling rate.Filling duration,occurrence time of maximal filling rate,duration of slight-increase period,and slight-increase period filling rate were less affected by weak light and high temperature.

Population dynamics of pests and their enemies in different cultivated rice fields

HUANG Dechao, ZENG Ling, LIANG Guangwen, CHEN Zhongnan

2005, 16(11):  2122-2125. 

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Through a whole year field investigation,this paper analyzed the population dynamics of pests and their enemies in organic and normally cultivated rice fields.The results indicated that the population of main pests varied more lightly in organic than in normally cultivated rice field,while subordinated pest species had little difference between these two fields.The individuals of enemies were more in organic than in normally cultivated rice field.It is suggested that the pest-control effect of enemies could be restored and became stronger when no chemical pesticides were applied.

Spatial distribution pattern and space dependence of Contarinia spand Erigonidium graminicola in jujube orchard

BI Shoudong, LIU Li, GAO Caiqiu, ZOU Yunding, DING Chengcheng, CAO Chuanwang, LIU Xiaolin, MENG Qinglei

2005, 16(11):  2126-2129. 

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With the principles and methodologies of geostatistics,this paper studied the spatial structure and space dependence of Contarinia sp.and its natural enemy Erigonidium graminicola in a jujube orchard at different date.The results indicated that the semivariogram of Contarinia sp.on 8 June,27 August and 19 October could be described by spherical model,showing an aggregated spatial distribution with the ranges of spatial dependence being 26.3,7.8 and 22.0 m,and the degrees of spatial dependence being 88.05%,85.77% and 87.58%,respectively.The semivariogram of Erigonidium graminicola could be also described by spherical model,showing an aggregated distribution with the ranges of spatial dependence being 28.3,22.5 and 22.2 m,and the degrees of spatial dependence being 90.09%,87.96% and 85.72%,respectively.It is suggested that Erigonidium graminicola is the dominant natural enemy against Contarinia sp.population in the examined jujube orchard.

Community succession patterns of pests and natural enemies in jujube orchard ecosystem

SHI Guanglu, LIU Suqi, CAO Hui, HUANG Minjia, XI Yinbao, ZHAO Lilin, LI Dengke, FENG Jin

2005, 16(11):  2130-2134. 

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Through investigation and by the methods of optimal partitioning,principal component analysis,and one-or two-dimensional ordination,this paper analyzed the main groups and succession trends of the pest and natural enemy communities at a jujube orchard of Taigu area.The results showed that the communities had more obvious dominant factors and temporal succession pattern.The first three principal components of the communities had a bigger variation,with an obvious follow effects.The community succession was temporally divided into four stages,i.e.,in the periods of pre-budding,leaf expanding and blooming,fruiting,and maturing.The dominant species of pests and their natural enemies were demonstrated.

Effects of Meloidogyne incognita initial inoculation density on ginger growth

GUO Yanyin, XU Kun, WANG Xiufeng, SU Baole

2005, 16(11):  2135-2139. 

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The study with potted ginger showed that Meloidogyne incognita infection could reduce the plant height,stem diameter,quantity of shoots,and fresh weight of stem,leaf and root,and finally,reduce ginger yield.With the enhancement of M.incognita initial inoculation density,the growth of ginger was damaged more severely,e.g.,under inoculating 50,100 and 200 M.incognita eggs per 100 g soil,ginger yield decreased by 27.91%,37.73% and 42.14%,respectively.The reproduction rate of M.incognita was also affected by the initial inoculation density,the lower the initial inoculation density,the higher the reproduction rate.When the inoculation density reached 746.20 eggs per 100 g soil,the reproduction rate was 1.

Effects of avermectin B_1a on soil microorganism and earthworm(Eisenia fetida)

SUN Yingjian, DIAO Xiaoping, SHEN Jianzhong

2005, 16(11):  2140-2143. 

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Avermectins are the pesticides widely applied in agriculture.This paper studied the effects of different concentration avermectin B_1a(AVM B_1a) on soil bacteria and fungi,soil respiration,and soil earthworm(Eisenia fetida).The results showed that in 4 test soils,bacteria were significantly inhibited when the AVM B_1a concentration was higher than 83.3 mg·kg^-1,while fungi were less impaired.Soil respiration was also inhibited by high concentration AVM B_1a,which differed with soil types.The half lethal dosage(LD₅₀) of AVM B_1a to soil earthworm was estimated as 4.63 μg·cm^-2 in filter paper contact test,and as 24.13 and 17.06 mg·kg^-1,respectively after treated 7 and 14 days in artificial soil.

Labeling of biocontrol agents ZJY-1 and ZJY-116 gfp gene and its ecological adaptability in cucumber rhizosphere

ZHANG Xin, ZHANG Bingxin, YU Jingquan, ZHANG Zhen, SHEN Weifeng, CHEN Zhenyu, SHI Jiang

2005, 16(11):  2144-2148. 

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The recombined plasmid pRP22-GFP contained with gfp gene and chloramphenicol resistant was successfully introduced into two biocontrol agents Brevibacillus brevis ZJY-1 and Bacillus subtilis ZJY-116.After seed inoculation,the survival and colonization of the two strains were studied by periodically retrieving the GFP-tagged strains in the cucumber rhizosphere based on the selective markers.The results showed that both the strains could successfully colonize in the rhizosphere during the whole life of cucumber,and a higher colonization level was observed during anthesis and fruition stages.In pot trials,they could migrate to the nearby non-inoculated spontaneous weed plants,and reestablish in the rhizosphere of plants subsequently grown in the same pot.

Accumulation of phenolic acids in continuously cropped cucumber soil and their effects on soil microbes and enzyme activities

MA Yunhua, WANG Xiufeng, WEI Min, QI Yanfeng, LI Tianlai

2005, 16(11):  2149-2153. 

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The study showed that in solar greenhouse continuously cropped cucumber soil,phenolic acids p-hydroxybenzoic acid,ferulic acid and benzoic acid had an obvious accumulation with increasing cropping year,and their contents were significantly higher after continuously cropped for 5～9 years than for 1～3 years.With the increasing concentration of treated exogenous phenolic acids,the amounts of bacteria,actinomycetes,total microbes,ammonibacteria,and nitrifying bacteria in cucumber root area increased first,but decreased then.Soil bacteria and actinomycetes had the largest amount at the concentration of 80 μg phenolic acids.g^-1 soil,while soil fungi(including Fusarium and Phytophthora) increased rapidly when the concentration of phenolic acids was lower than 120 μg·g^-1 soil.With increasing phenolic acids concentration,soil enzyme activities also increased first but decreased then,with the peak values differed in different treatments.

Screening of phytase-producing strain and its optimal solid state phytase-producing conditions

WANG Shihua, HU Kaihui, LIN Wenxiong

2005, 16(11):  2154-2157. 

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Phytase can catalyze phytate hydrolyzed into inositol and phosphoric acid,and its application could make the phytic acid in animal feeds become more available,decrease feed cost,and at the same time,protect eco-environment.In this paper,a phytase-producing strain Trichoderma Viride LH374 was obtained through isolation and mutation,and its optimal conditions for solid state fermentation and phytase production were investigated.The results suggested that the optimal conditions of solid state fermentation were straw:rice bran ratio 8:2,medium initial pH 6.5,temperature 30 ℃,culture duration 96 h,and moisture content 60%.Under the optimal conditions,LH374 could accumulate phytase up to 1 580 U·g^-1.

Heavy metals content and pH value in water environment of wild Chinese alligator(Alligator sinensis) habitat:A preliminary study

JIANG Hongxing, WU Xiaobing, WU Lusheng

2005, 16(11):  2158-2161. 

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In order to reveal the reasons of the dramatic decline of wild Chinese alligator population,an investigation on its habitat status was made across the National Natural Conservation Regions of Chinese alligator in south Anhui Province from 2002 to 2003.Water samples from²1 sites were collected,and their heavy metals(Cu,Zn,Cd and Pb) content and pH value were measured.The results showed that the pH value was 7.84?0.62,with no significant difference between the waters with and without Chinese alligator,but with significant difference(P<0.01) among 3 Chinese alligator habitats.In the waters with and without Chinese alligator,no significant difference was observed in the contents of test metals except Pb.The possible pollution source of Pb in wild Chinese alligator habitat was analyzed,which could provide reference for Chinese alligator conservation.

Effects of Cd contamination on paddy soil microbial biomass and enzyme activities and rice physiological indices

ZENG Lusheng, LIAO Min, HUANG Changyong, LUO Yunkuo

2005, 16(11):  2162-2167. 

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A pot experiment with rice under submerged condition showed that with the increase of Cd concentration,soil microbial biomass carbon(C_mic)and nitrogen(N_mic) increased initially but decreased at a certain concentration,and the turning points varied with different soil types.Soil enzyme activities had the similar variation trend with soil C_mic and N_mic,and the turning points varied with different soil types and soil enzymes.The variation coefficients were in order of dehydrogenase activity>acid phosphatase activity>urease activity.Soil respiration rate and metabolic quotient increased tardily with increasing cadmium concentration.The chlorophyll content of rice increased initially but decreased then with the increase of Cd contamination,and the turning points differed with different soil types.Rice proline content and peroxidase activity were enhanced gradually with increasing cadmium concentration.The variation coefficients of rice physiological indices on paddy soils derived from silty loam and clayed red earth were in order of peroxidase activity>chlorophyll content>proline content,and peroxidase activity>proline content>chlorophyll content,respectively.Correlation analysis indicated that there was a close correlation between the variations of soil microbial biomass and enzymatic activities and rice physiological indices under Cd contamination.

Variation characteristics of leachate quality in a semi-aerobic municipal solid waste landfill

YANG Yufei, HUANG Qifei, WANG Qi, LIU Yuqiang, DONG Lu

2005, 16(11):  2168-2172. 

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A large-scale semi-aerobic landfill set(21 m?3.8 m?6.0 m) was constructed to study the variation characteristics of pollutants in the landfill leachate.The results showed that after 39 weeks,the concentrations of COD_Cr,BOD₅ and NH⁺₃-N in the leachate declined rapidly,which reached 173,30 and 15 mg稬^-1 respectively,and the reducing rate of NH⁺₃-N was 99.6%.The pH value was below 7 during the first 2 weeks,but became weak alkaline after three weeks.Based on the experimental data,the attenuation equations of pollutants in the leachate were built.

Ecological toxicity of aluminum-based coagulant on representative corps in neutral environment

ZHANG Kaisong, ZHOU Qixing

2005, 16(11):  2173-2177. 

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By the terrestrial ecotoxicological methods of seed germination and root elongation,and with aluminum-based coagulant AlCl₃ which was widely used in wastewater and water treatment as an example,this work studied the toxicological effects of aluminum-based coagulants on representative crops,including radish Raphanus sativus,cabbage Brassica chinensis and wheat Triticum aestivum,over a range of exposure concentrations under the neutral condition(pH=7.0),with contrast to an acid condition(pH=4.00).The results indicated that there was a significantly positive correlation between the concentration of AlCl₃ and the inhibitory rate of root elongation and seed germination either under pH 7.0 or 4.0(P<0.01).Cabbage and wheat was more susceptive to AlCl₃ toxicity under acid than under neutral condition,while radish was in adverse.The minimum inhibitory concentration of AlCl₃(<2.0 mg稬^-1) was lower under neutral than under acid condition.

Response of Vetiveria zizanioides to Pb²⁺ stress

HAN Lu, ZHANG Xiaoping, LIU Birong

2005, 16(11):  2178-2181. 

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The study on the eco-physiological indices of V.zizanioides under Pb²⁺ stress showed that with the increase of Pb²⁺ concentration(0～8 mmol·L^-1) in water culture,the growth of V.zizanioides seedlings was badly influenced.Their leaves'conductivity increased,while SOD activity increased first and decreased then,but still higher than control.There was a positive correlation between SOD activity and Pb²⁺ concentration.POD and CAT activities were also increased first and decreased then,but when the Pb²⁺ concentration was>4 mmol·L^-1,these enzyme activities were lower than the control,and had a significantly negative correlation with Pb²⁺ concentration.It was considered that the increase of enzyme activities was resulted from the adaptability of V.zizanioides stressed by Pb²⁺,while high concentration Pb²⁺ had an inhibitory effect on enzyme activities.

Impacts of Cd and Pb pollution on soil microbes in tobacco root zone and on tobacco leaf quality

MA Xinming, LI Chunming, YUAN Zuli, XIONG Shuping, ZHANG Guilong

2005, 16(11):  2182-2186. 

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A pot experiment was conducted to study the impacts of Cd and Pb pollution on soil microbes in tobacco root zone and the quality of tobacco leaves.The results indicated that the higher concentrations of Cd and Pb in soil,the less soil microbes in tobacco root zone.When the levels of Cd and Pb were ≤10 and ≤300 mg·kg^-1,respectively,the individuals of soil microbes decreased acutely.As for the quality indexes of tobacco leaves,the ratios of reductive sugar/nicotine and total-N/nicotine increased,and the main components became disharmony,which was disadvantage for the fragrance forming of tobacco leaves.The K content in tobacco leaves had a negative correlation with soil Cd and Pb concentrations,but a significantly positive correlation with the quantity of potassium bacteria in root zone under Cd pollution.No significant correlation was observed between the K content in tobacco leaves and the quantity of potassium bacteria in root zone under Pb pollution.

Environmental cost of rice production in Dongting Lake area of Hunan Province

XIANG Ping'an, HUANG Huang, YAN Huimin, ZHOU Yan, ZHENG Hua, HUANG Xingguo

2005, 16(11):  2187-2193. 

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To evaluate the environmental cost of rice production is of significance for the sustainable development of agriculture and the set-up of green GDP accounting system.In this paper,the environmental cost of rice production in Dongting Lake area,one of the main bread baskets in China,was evaluated from the aspects of pesticide pollution,chemical fertilizer pollution,greenhouse gases emission,plastic film persistence,paddyfield gleyization,and polderization.The results showed that in 1999,the total environmental cost of rice production in this area was 41.91 billion yuan,equivalent to 26.8% of its total agricultural production value,or 28.5% of the gross output of its planting industry.For the sustainable production of rice,the strategies for decrease environmental cost intrinsically were put forward.

Effects of illumination on overlying water quality and on phosphate adsorption by sediment

JIANG Xia, JIN Xiangcan, YAO Yang, LI Lihe

2005, 16(11):  2194-2198. 

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By the method of laboratory simulation,this paper studied the effects of illumination on the quality of overlying water and on the phosphate adsorption by sediment in a clean lake region.The results showed that under anaerobic condition,illumination could increase the pH value and the dissolved oxygen(DO) concentration of overlying water,while under aerobic condition,the concentration of dissolved inorganic phosphate(DIP) in overlying water declined fast at the beginning of the experiment,which indicated that DIP concentration was controlled by the DO concentration at the water-sediment interface.With the time went on,the DIP concentration in overlying water was much lower in the light than in the dark,indicating that illumination was the dominant controlling factor to the DIP concentration in overlying water.Phosphate could be adsorbed by the sediment with continuously loading,and the adsorbed amount varied with different environmental conditions.The effect of illumination on the phosphate adsorption by sediment was limited by the environment whether being aerobic or anaerobic.

N and P removal characters of eutrophic water body under planted float

ZHOU Xiaoping, WANG Jianguo, XUE Lihong, XU Xiaofeng, YANG Linzhang

2005, 16(11):  2199-2203. 

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The study on the N and P removal and N₂O release of eutrophic water body under planted float Ipomoea aquatica and Oenanthe javanica showed that planted float had a good effect on the removal of N and P from eutrophic water body.The bioaccumulation of N and P by the plants accounted for 40.32%～63.87% of the N and P removal,respectively,suggesting that plant uptake was the main removal process.Within the treating period,there was a rapid and sufficient nitrification but a slow and insufficient denitrification in the planted float system,and thereby,planted float system had a high NH⁺₄-N removal rate and NO^-₃-N accumulation.The presence of planted float reduced the release flux of N₂O,which was 17.14 μg N·m^-2·h^-1 for Ipomoea aquatica,37.38 μg N·m²·h^-1 for Oenanthe javanica,and 85.08 μg N·m^-2·h^-1 for the control.

Induction of pond-cultivated Anguilla japonica gonadial development by controlling temperature in high temperature season

WANG Guangjun, XIE Jun, YU Deguang, ZHU Hongyou

2005, 16(11):  2204-2207. 

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In this study,the pond-cultivated Anguilla japonica was induced to mature by artificially controlling temperature at 18±2 ℃ in high temperature season(from June to September),with injection of hCG and CPE.The results showed that both the male and the female eel could be induced to mature,and the artificial maturation induction rate was 73.33% and 67.77%,while under non-controlling temperature 25～32 ℃,the maturation induction rate was 0 and 33.33%,respectively.In an ovulation induction test,the matured female eels were induced,with a spawning inducement rate of 70%,and a fertilization rate of 32%,which approached or reached the levels in low temperature season(with an average of 62.1% and 34.2%,respectively),and the zygote developed normally.At the temperature 22 and 24 ℃,the zygote hatched to fry in about 39 h 15 min and 34 h 9 min.The experiment proved that it was possible to induce the eel to mature by controlling temperature in high temperature season,which provided some theoretical foundations for the techniques of artificially breeding eel in whole year.

Research advances in soil nitrogen cycling models and their simulation

TANG Guoyong, HUANG Daoyou, TONG Chengli, ZHANG Wenju, WU Jinshui

2005, 16(11):  2208-2212. 

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Nitrogen is one of the necessary nutrients for plant,and also a primary element leading to environmental pollution.Many researches have been concerned about the contribution of agricultural activities to environmental pollution by nitrogenous compounds,and the focus is how to simulate soil nitrogen cycling processes correctly.In this paper,the primary soil nitrogen cycling processes were reviewed in brief,with 13 cycling models and 6 simulated cycling processes introduced,and the parameterization of models discussed.

Application value of organic ground surface mulch in urban forestry construction

WANG Cheng, QIE Guangfa, PENG Zhenhua

2005, 16(11):  2213-2217. 

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This paper summarized the development process of organic ground surface mulch,and analyzed its important application value(such as the functions of improving soil physical and chemical properties,promoting plant growth,beautifying urban landscape,and preventing soil dust,etc.),and its values in protecting environment and benefiting economy.The problems in the application process of organic ground surface mulch were discussed,and the actual impendence and broad development space of its production and application in our urban forestry construction were pointed out.

Soil chemical property changes in vegetable greenhouse fields

LIU Yanjun, JIANG Yong, LIANG Wenju, LI Qi, WEN Dazhong

2005, 16(11):  2218-2220. 

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To explore the changes of soil chemical properties in vegetable greenhouse,a comparative study was carried out with the samples gathered from vegetable greenhouse fields and their adjacent upland fields in Damintun Town,Xinming County,Liaoning Province.The results showed that compared with upland fields,the contents of soil organic carbon and total nitrogen in greenhouse fields increased significantly.At the depth of 0～30 cm,soil organic carbon in greenhouses of 1-,4-and 10-year increased by 31.09%,35.44%,and 66.80%,respectively,compared with the upland soil.Soil nitrate content at the depth of 0～30 cm in greenhouse fields was 5.05～12.49 times as much as that in upland fields.The nitrate content in different soil layers increased with the increasing age of greenhouse field.,e.g.,at the depth of 20～30 cm,soil nitrate content was significantly higher in 10-year than in 1-and 4-year greenhouse field,with an increase of 65.73% and 50.89%,respectively,and 6.55 times as much as that in upland field,which indicated that soil nitrate transported downwards,and obviously enriched in deeper soil layers under heavy application of fertilizer.Also with the increasing age of greenhouse field,soil pH decreased,while soil soluble salts accumulated.

Reconstruction of Polytrichum juniperinum population dynamics in a mire of China

BU Zhaojun, YANG Yunfei, WANG Shengzhong, WANG Xianwei, DAI Dan

2005, 16(11):  2221-2223. 

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By using ‘history reconstruction method',this paper studied the dynamics of two Polytrichum juniperinum populations with and without sporophytes.The population with sporophyte production experienced a dynamic process from increase to stabilization,while that without sporophyte production experienced a process from increase to decrease.Before 2003,both the increase rate and the birth rate of two populations decreased continuously,with the death rate showing the tendency from decrease to a continuous increase.The advantages of 'history reconstruction method' in studying population dynamics were proved and discussed.