Table of Content

25 January 1995, Volume 6 Issue 1

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Articles

Application of future net worth model in early selection of Larix kaempferi

Xu Fuyu, Zhang Songyun, Wang Lihua

1995, 6(1):  1-4. 

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To accelerate the genetic improvement process for Japanese larch (Larix kaempferi), thefuture net worth (FNW) model used for early selection is established in this paper.According to the calculation of residual squares sum and nonlinear regression correlation indices, the squares root tatio of genetic heritability g(x), and the juvenile-mature correlation coefficients r(x) with relative ages can better fit the quadratic function.If g(x)=1and k=0.75, selection should be made at age 6 and 11 respectively for tree height and itsincrement, and to predict the volume at mature stage with the indicators of tree heightand its increment, selection should be made at age 9 to 10.If g(x) and r(x) are quadraticfunctions, and interest rate (IR) is 0.05, the optimum selection ages for tree height andits increment should be 11-12 and 9-10 years respectively, and 5-7 year for the volume, using tree height as predictor.The result shows that the determination of optimumselection ages by applying FNW model is influenced by different rotation ages, interestrates and other economic factors.The efficiency of early selection for Larix haempferi,the influence of basic parameters on FNWmodel and the convergence range of optimumselection ages are also discussed in this paper.

Turnover of fine roots in pure and mixed Cunninghamia lanceolata and Michelia macclurei forests

Liao Liping, Chen Chuying, Zhang Jiawu, Gao Hong

1995, 6(1):  5-10. 

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Studies on biomass, productivity and annual turnover of fine roots in pure and mixed C.lanceolata and M.macclurei forests show that the biomass of living fine roots in threestands of pure and mixed forests is respectively 880, 3035 and 1560 kg·ha^-1, and that ofdead ones is 235, 398 and 565kg·ha^-1, respectively.The annual turnover of fine roots is 1.29, 1.42 and 1.40, their annual productivity is 1137, 4318 and 2179 kg·ha^-1, and annual mortality is 497, 595 and 1149 kg·ha^-1, corresponding to 36.8.21.6 and 65.9% ofannual litter fall in each stand.It is concluded that mixed plantation has a higher productivity and better ecological coordination than pure stand.

Comparison of growth dynamics between first generation and regeneration of Pinus mossomiana

Peng Shaolin

1995, 6(1):  11-13. 

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In this paper, the growth dynamics of first generation and regeneration of Pinus massoniana is compared by tree ring analysis.The results show that the first generation can growwell on poor barren land.The growth peak is at 35-40 years.The individuals of regeneration degenerated seriously, which implies that continuous plantation of poly-generationis not a reasonable management, and stand-remaking should be carried out when the age of forest is about 35 years old.

Structure of transpiration ecoboundary layer of organs of poplar seedlings

Guo Jishan

1995, 6(1):  14-16. 

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The thickness of transpiration ecoboundary layer of leaves, stems and whole plants ofpoplar seedlings is measured by means of ³H₂O tracing techniques, and the relationship between transpiration of poplar seedling and environment is studied.The results show thatthe transpiration rate of upper leaf surface is larger than that of lower surface, and that ofleaf margins is larger than that of the midribs.The transpiration ecoboundary thicknessof leaf is 5-6cm, while that of whole seedling is 24cm.

Dynamics of carbon, hydrogen and nitrogen elements in Rhizophora stylosa mangrove community at Yinluo Bay of Guangxi, China

Zheng Wenjiao, Lin Peng, Xue Xiongzhi, Lu Changyi, Zheng Fengzhong, Yin Yi

1995, 6(1):  17-22. 

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Studies on C, Hand Ncontents and storages, annual energy and annual O₂ net productions in a 70 years old Rhizophora stylosa mangrove community at Yinluo Bay of Guangxishow that the C, H and N contents in different parts of the plant are 43.86-51.65%,4.35-5.72% and 0.28-1.44%, and their storages in the community are 14117.7,1446.4 and 158.5g·m^-2 respectively.The annual net fixed C, Hand N by the communityare respectively 798.51, 86.31 and 12.33g·m^-2, among which, annual reserved C, Hand Nare 441.22, 45.of and 5.37 g·m^-2, and annual outputs through litter are 357.29,41.30 and 6.96g·m^-2 respectively.The annual net production of energy by the community is 31227KJ·m^-2, and annual net release of O₂ is 2129g·m^-2.

Effect of grazing intensity on pasture structure and tissue turnover in a perennial ryegrass pasture ecosystem

Xia Jingxin, J. Hodgson, C. Matthew, Zhu Changping

1995, 6(1):  23-28. 

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This paper studies the effect of grazing intensity of the tiller size, tiller density, pastureproductivity and tissue turnover in a perennial ryegrass pasture ecosystem.The resultsshow that hard grazing leads to a greater tiller density and a lesser tiller weight than laxgrazing does.The net productivity is higher under hard grazing, because under conditionof lax grazing, the higher growth rate of pasture is offset by its senescence rate.Thereare advantages to spring-summer pasture production from a flexible pasture management.

Ecological field gradient of Anewolepidium chinense under different population densities and its dynamic characteristics

Wang Deli, Zhu Tingcheng

1995, 6(1):  29-33. 

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Through a fixed case study on the ecological field of plant individuals and populations.theconcept of ecological field gradient is put forward, and the ecological field gradient modelsof plant and Anewolepidium chinense individuals are established.The variation forms ofA.chinense crown field gradient conform to the Rayleigh distribution, and there is onemaximum value at the point r=.The A.chinense root system field gradient variesin a complex distribution, and there are two maximum values at the points r=0 and r=a.The ecological field gradient of A.chinense individuals is related to its population density.

Fire regime of Aneurolepidium chinense-herbage steppe

Zhou Daowei, Zheng Huanneng, Zhou Yiliang

1995, 6(1):  34-38. 

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In this paper, the fire regime of Aneurolepidium chinense-herbage steppe is studied and adevised method is used to study the fire cycle of treeless grassland.The results show thatgrassland fire often occurs in May and October, the natural fire cycle is 4 years, and theman-made one is 25 years.The herbaceous layer on grassland is burned by the fire.andthe burned dung of livestocks is the major factor affecting the internal pattern of burnedarea.The ecological implications of phenomena produced by burning are discussed and thefire-generated factors are definited.

Analysis of village-scale eco-agricultural types on hilly plain of central Hubei Province

Cao Cougui, Chen Yuhua, Liu Yanjun

1995, 6(1):  39-43. 

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The eco-agricultural types on hilly plain of central Hubei Province are analyzed in a village-scale with quantification method Iand system cluster method.The results show thataccording to the characteristics of natural resources and the situation of eco-agriculturalconstruction in the region, twenty-five villages are classified into four ecolomic and environmental types and eight eec-agricultural ones.The developmental models of eco-agriculture in the region are put forward.

Relationship between soil rauna and soil environment in jujube garden or Shuidong,Anhui Province

Qian Fusheng, Wang Zongying

1995, 6(1):  44-50. 

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Soil fauna in jujube garden of Shuidong, Anhui Province was investigated from December 1992 to February 1993.5875 individuals are collected, which belong to 5 phyla, 11 classes, 28 orders and 35 genera.The dominant genera are Acari and Nematoda, and the common genera are Enchytraeidae and Collembola.Acomparison of 7 plots show that thelonger the jujube trees are planted.the richer the groups and individuals of soil fauna are.The group of soil fauna is increased with increasing soil nutrients, but decreased with increasing soil PHand bulk density.Both the group and individuals are decreased with soildepth.

Articles

Nutritional effect of mixed broadleaved and coniferous forest on inhibiting Dendrolimus population growth

Zhou Zhangyi

1995, 6(1):  51-55. 

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The study shows that the metabolic energy of Dendrolimus is originated from fat.When Pinus tabulaeformis is mixed with Cotinus coggygria or Quencus aliena, its leavescontain less crude fat and total sugar, and their C/N ratio is lowered.Because Dendrolimus feeds on pine needles in the mixed forest, the digestion coefficient.weight increment, pupation rate and reproduction capacity of its larvae are all decreased comparing with those in pure forest.

Mathematical simulation on relatiouship of mean lethal rate of nuclear polybedrosis virus to its host insect and temperature

Ye Gongyin, Hu Cui, Lu Chenyin, Li Zichuan

1995, 6(1):  56-60. 

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In this paper, the mathematical model describing the relationship of mean lethal rate V(T) of nuclear polyhedrosis virus (NPV) to its host larvae and temperature (T) is drawnas follows: V(T)=ρ(25℃)T/T₂₅exp △H_A^≠/R (1/T₂₅-1/T] / 1+exp[△H_H/R (1+T_1/2H-1/T)] of which, T₂₅ and R are 298.15°K and 8.314J·K^-1·mol^-1; respectively, and P(25℃),△H_A^≠, △H_H and T_1/2H are unknown parameters.The model can well fit to describe therelationship of mean lethal rate of NPV from tea geometrid Ectropis obliqua hypulina to its host larvae infected with the virus at the beginning of each instar and temperature.Itis also fit to simulate the relationship between V(T) and T of Heliothis zea NPV, Calleria mellonella NPV and Anticarsia gemmatalis NPV to their host larvae, respectively.

Rate summation effect on mean daily development rates in development process of insect

Liu Shusheng

1995, 6(1):  61-66. 

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The relationship between temperature and development rate of insect follows a sigmoidcurve.This paper describes the ranges of varying temperatures favourable to insect development, and presents a simulation study on the effect of rate summation which is a directconsequence of curvilinear relationship between temperature and development rate.Thesimulation is based on the development data of Lipaphis erysimi.The results show thatunder the prerequisite of not considering the effect of temperature variation on instantaneous rate of development, the rate summation effect will lead to a faster development atvarying temperatures than that at a constant temperature within the range of low temperature.Areverse consequence is resulted within the range of high temperature, and thedifference increases rapidly with the amplitude of temperature variation.Because meandaily development rate varies with the pattern and amplitude of temperature variation,and the development under different varying temperatures can be predicted by the constant temperature rate curve, it's suggested that in terms of making prediction of insectdevelopment under favourable temperatures, the experimental data obtained under constant temperatures have a wider application than those obtained under varying temperature regimes.

Preliminary study on the relationship among Macrocentrus linears,Ostrinia furnacalis and spring corn

Lu Zhongxian, Yang Zhangfa, Hu Cui

1995, 6(1):  67-70. 

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The study shows that the peak of M.linears occurrence is about 6-9 days later than thatof O.furnacalis adults, and conformed with the tasseling of spring corn.When the corn istasseling, most of O.furnacalis larvae are in 3rd and 4th instar, which are easy to be parasitized by M.linears.Owing to the changes of morphological structure and nutritivecomposition of tassels after flowering, O.furnacalis larvae are forced to move downwardto find more favorable foods.M.linears are attracted by O.furnacalis larvae and its parasitism is closely related to the development of O.furnacalis larvae and the growth periodof corn.

Biology of Neosalanx oligodontis in Yuni lake of Hubei Province

Gong Shiyuan, Zhang Xunpu

1995, 6(1):  71-75. 

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The study shows that the reproduction period of Neosalanx oligodontis is from earlyMarch to late May.Its spawning periods are the last ten days of March and April.Theage of sexual maturity is one year, belonging to the multiple spawning type.The fishfeeds zooplanktons during its whole life.After one year, its average total length is 44.2mm, and average body weight is 0.252g.The parents die off soon after their last spawning, and their life period is only one year.

Retention of allochthonous nutrients by ecotones or Baiyangdian Lake

Yin Chengqing, Lan Zhiwen, Yan Weijin

1995, 6(1):  76-80. 

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Field experiments show that reed community and ditches in Baiyangdian Lake ecotonescan effectively retain nutrient elements from land sources.Under moderate hydrologicalcondition, water flows through the ditches and the root zone of reed community.The retention of total nitrogen (TN) and total phosphorus (TP) by a 300m ditch is measured tobe 42 and 65 % respectively, and that by a 4m distance of reed community soil is respectively 64 and 92%.The retention by reed community mainly happens at the rhizosphere,while the removal of organic matter is less in comparison with inorganic nutrients.Thecomponents retained at the largest ratio are ammonia nitrogen and ortho-phosphate phosphorus.These retention effects play an important role in stabilizing the adjacent ecosystems and reducing the eutrophication of waters.

Identification of mechanism model on population dynamics of Prorocentrum sigmoides at Dapeng Bay or the South China Sea

Huang Weijian, Qi Yuzao

1995, 6(1):  81-86. 

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Amechanism model for simulating the population dynamics of Prorocentrum sigmoides at Dapeng Bay of the South China Sea is established.Among the factors such as temperature, salinity.dissolved oxygen (DO), dissolved inorganic phosphate (DIP), dissolvedinorganic nitrate and nitrite, and PH, the temperature is a limiting factor of P.sigmoidesgrowth.By applying hierachy to the back substitution and introducing auto-regression ordering into the model identification, a simultaneous regression model derived from six auto-regression and non-linear regression models is established.The fitting degree betweensimulated and observed data is 81.7%.

Tolerance mechanism of crops to Cd pollution

Yang Jurong, He Jianqun, Zhang Guoxiang, Mao Xianqiang

1995, 6(1):  87-91. 

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Studies on Cd forms in8 kinds of crops under Cd pollution show that the Cd tolerance ofcrops is closely related to the distribution of Cd forms.In Cd-tolerant crops, the percentage of Cd combined with protein (polypeptide) is higher, organic Cd and Cd hydrophos-phare are more, and Cd-induced protein contains definite amounts of bound Cd which limits the existence of free Cd.In crops with lower Cd tolerance, big molecular protein isrich in Cd.

Analytical method of polycyclic aromatic hydrocarbons (PAHs) in soil and plant samples

Song Yufang, Ou Ziqing, Sun Tieheng, A. Yediler, G. Lorinci, A. Kettrup

1995, 6(1):  92-96. 

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Soil, plant and seed samples are respectively extracted by tetrahydrafuran, methanol andethyl acetate ultrasonically.The extracts are evaporated by rotary evaporator, cleaned upon silica gel column and analyzed on HPLCwith fluorescence detector.The recovery ofPAHs is 45.68-93.42% for soil, 77.59-108.13% for plant, and 79.11-98.96% forseed, depending on the physico-chemical properties of individual PAHcompounds.Dichloromethane and tetrahydrafuran are the suitable extracting agents for soil, andmethanol and ethyl acetate for plant and seed.respectively.This method has the characteristics of simplicity, rapidity, sensitivity and reliance, and can be used for the study ofPAHs in soil-plant system.

A primary discussion on agroecosystem diversity

Wen Dazhong

1995, 6(1):  97-103. 

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The study of agroecosystem diversity is quite important for conserving agricultural biodiversity and promoting sustainable development of agriculture.In this paper, the conceptand characteristics of agroecosystem diversity are discussed, the method of agroecosystemclassification for agroecosystem diversity study is established, and some indexes describing agroecosystem diversity features are introduced.Some suggestions for further developing this research field are put forward.

A preliminary research on the effect of nitrogen and phosphorus supply on N₂O emission by crops

Chen Xin, Shen Shanmin, Zhang Lu, Wu Jie, Wang Xueqiang

1995, 6(1):  104-105. 

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The preliminary results with detached leaves and seedlings of corn, soybean and sorghumfrom pot and field experiments indicate that inorganic nitrogen supply can significantly enhance the N₂O emission and NO₃^- concentration in plants in the case of phosphorus deficiency and of less light, but phosphorus Supply and sunlight condition can markedly reduce the N₂O emission and NO₃^- concentration in the plants.It's concluded seemed thatthe N₂O emission is a kind of physiological protection to avoid NO₃^- accumulation in plantswhen nitrogen metabolism in plants is in disorder and mineral nitrogen is in over supply.

Artificial formation of aerial nodules on Casuarina cunninghamiana

Zou Hua, Zhang Zhongze, Zhang Chenggang, Ding Jian, Wang Yuying, Fu Li

1995, 6(1):  106-108. 

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Using test tube-slide method to culture plants, the aerial nodules are successfully bred onshoots of C.cunninghamiana seedlings.The pricked and non-pricked sites on stem are inoculated with Frankia strain Cool which was isolated from root nodules of same plantspecies.and the aerial nodules are appeared 40 days after,which arise from the pericycleof stem.The lobes of aerial nodule are similar to those of root nodules in size and shape,and each lobe has a nodule root at its top.Transverse section of aerial nodule shows thatthe endophyte hyphae have diaphragm and some hyphae pass through two plant cells.Histological characteristics of aerial and root nodules do not show significant differences.The aerial nodules have a mean ARA value (n mol C₂H₄·min^-1·g^-1 fresh weight ofnodules) of 28.79, compared to 81.96 of their root counterparts.The nitrogenase activities of both aerial and root nodules can be reduced by low concentration of NH₄⁺(0.47g·L^-1 NH₄)₂SO₄) and inhibited by 2.0g·L^-1(NH₄)₂SO₄.