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    25 March 2000, Volume 11 Issue 2
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    Articles
    Seed rain and seed bank of constructive species in evergreen broadleaved forest at Chongqing Simian Mountain
    PENG Jun, LI Xuguang, FU Yongchuan, LIU Yucheng
    2000, 11(2):  23-25. 
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    The study shows that the early and late seed rains of constructive tree species in evergreen broadleaved forest at Chongqing Simian Mountain had no activity.The bigger the seeds of the species and the earlier or later the seeds of the species matured,the higher the proportion of the seed rain damaged by animals.The quantitative variation of seed rain,active seed rain and seed bank did not take place at the same time.At early time, the number of seed banks of Castanopsis fargesii,Lithocarpus glabra,Quercus myrsinrefolia,Castanopsis plasyacantha,Cinamomum subavenium. which own more active seed rain increased by geomitric series.The seed banks of Castanopsis orthacantha and Schima argentea were small,only survived a short time,and did not sprout next year.The quantitative dynamics of seed banks and their increasing or decreasing rates were decided by the proportion damaged by animals,dying speed of seeds and their resistance to pathogens and adverse circumstances,and the state of seed germination.
    Relationship between flooded situation and poplar growth on beach land of Yangtze river in Anhui
    WU Zemin, SUN Qixiang, DUAN Wenxiu
    2000, 11(2):  26-30. 
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    Through the analysis on the dynamics of flooding and the annual ring series of poplar trees on the beach land of Yangtze river in Anhui in the period of 1989～1997,the related models on flooded situation and ring growth were built.The results showed that there existed significant differences in flooding time and depth on different elevations of beach land,which made a great influence on the annual ring growth of poplar trees.The maximal flooded depth was more important than flooded time for its influence on ring growth.In addition,the flooded situation in August and September of previous year had a significantly negative influence on the ring growth of current year.The beach land with a maximal flooded depth of more than 2m was not suitable for high productive plantation of timber.It is suggested that a little more dense plantation should be managed for the production of pulp materials.
    Population density of Eucalyptus urophylla plantation
    HUANG Baoling, LU Chengqun
    2000, 11(2):  31-33. 
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    This paper dealt with the relationships and correlation models of the population density of 5.6 years old Eucalyptus urophylla plantation with its crown width,diamter at breast height(DBH),tree height,individual standing volume,stand volume,wood properties and survital rate.The results showed that the population density remarkably affected DBH,individual standing volume,crown width,live branch height,stand volume and wood fiber width;but not affect tree height,basic density of wood,and length of wood fibers.It had a positive relationship with stand volume,live branch height and wood fibers width,and a negative relationship with DBH,individual standing volume and crown width.In addition, E.urophylla had a wide range of reasonable density.For short-rotation puplwoods,the optimum planting density of E.urophylla is 2000 individuals per hectare.
    Mixing of Cunninghamia lanceolata with Michelia macclurei and restoration of self sustaining mechanism in G. lanceolata plantation
    WANG Silong, LIAO Liping, DENG Shijian, GAO Hong, HUANG Zhiqun
    2000, 11(2):  34-37. 
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    The formation of self-sustaining mechanism is one of the major objectives for the sustainable management of plantations.In this study,the incorporation of different proportions of native Michelia macclurei into Cunninghamia lanceolata plantation was practiced to restore the degraded C.lanceolata plantation,and the comparison of nutrient cycling characteristics and soil nutrient concentrations was made among four types of plantation stand with different mixed rate of native M.macclurei representing four different restoration stages of degraded C.lanceolata plantations.With the increase of the proportion of M.macclurei in the plantation,the litterfall and returned nutrients N,P,K,Ca and Mg increased.The nutrient cycling efficiency increased significantly, e.g.,that of N and Mg increased from about 0.1 for the degraded pure C.lanceolata plantation to above 0.5 for the pure M.macclurei plantation.Soil organic matter and nutrients also elevated.It is suggested that the self-sustaining mechanism of the C.lanceolata plantation forest gradually reformed as the proportion of native M.macclurei mixed in the plantation increased. The criteria to determine the proportion of native broad-leaved tree species mixed in C.lanceolata plantations for the purpose of sustainable management should be based on whether the self-sustaining mechanism was reformed and whether the soil nutrient status was improved.
    Distribution patterns of root systems of main planting tree species in Weibei Loess Plateau
    ZHAO Zhong, LI Peng, WANG Naijiang
    2000, 11(2):  38-40. 
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    The vertical patterns of root systems of Pinus tabulaeformis,Robinia pseudoacacia,Platycladus orientalis,Pinus sylvestris var. mongolica,Pinus armandi,Prunus armeniacia var. ansu planted in the Weibei Loess Plateau were studied with soil auger.Site conditions had a significant effect on the vertical root distribution of R.pseudoacacia,of which,soil moisture is the key factor.Soil species and soil structure also had great effect on the distribution. P.tabulaeformis had a maximum rooting depth at its young stage(8 years old),but the root density increased with age. There was a great difference in vertical root distribution among the tree species,of them, R.pseudoaccia rooted deepest,which negated the opinion that R.pseudoacacia is a shallow rooted tree species.According to the vertical root distribution of the tree species,the productivity of these species in the south-facing site of yellow loess soil would be in order of R.pseudoacacia>Prunus armeniacia var. ansu> P.tabulaeformis>P.sylvestris var. mongolica>P.armandi>Platycladus orientalis.
    Decomposition process of Chinese fir stump roots and changes of nutrient concentration
    HUANG Zhiqun, LIAO liping, GAO Hong, WANG Silong, YU Xiaojun
    2000, 11(2):  41-43. 
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    With space as a substitute for time,the changes of the density of stump sapwoods and heartwoods,and the releasing process of major nutrients during the decomposition of Chinese fir stump roots were investigated.The yearly loss rate of the densities of sapwoods and heartwoods was 2.767×10-2 and 2.255×10-2 respectively during decomposition.The contents of N and P in sapwoods and roots decreased continually, while those in heartwoods increased during the first stage of decomposition,and then decreased.The K concentration in stump roots decreased remarkably during first two years, and the content of organic substances decreased during the whole decomposition process.The N,P and K concentrations in roots were higher than those in stump sapwoods and heartwoods at the beginning of decomposition,but bet content of organic substance was opposite.
    Response of broadleaved Pinus koraiensis forests in Xiaoxinganling Mt to global climate change-a dynamic modeling
    DENG Huiping, WU Zhengfang, ZHOU Daowei
    2000, 11(2):  44-47. 
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    In this paper,the Forest Gap Model and four General Circulation Models (GCMs) were employed to investigate the dynamic response of broadleaved Pinus koraiensis forests in Xiaoxinganling Mountains of China to global climate change. Under CO2 doubling which was simulated by the scenarios of Oregon State University and Goddard Institute for Space Studies,the biomass of broadleaved Pinus koraiensis forest increased and the current Picea-Abies-broadleaved Pinus koraiensis forest would gradually develop to Betula costata-Tilia amurensis-Ulmus laciniata-broadleaved Pinus koraiensis forest.Under the scenarios of Geophysical Fluid Dynamics Laboratory at Princeton University and United Kingdom Meteorological Office, Pinus koraiensis and other coniferous species would be replaced by broadleaved species such as Quercus mongolica,Tilia amurensis and Ulmus laciniata, and the broadleaved Pinus koraiensis forest would change to broadleaved forest,due to the great range increasing temperature by the scenarios.The future warming rate would determine the succession of broadleaved Pinus koraiensis forest.
    Relationship between main vegetation types and climatic factors in Inner Mongolia
    NIU Jianming
    2000, 11(2):  48-53. 
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    The relationship between main vegetation types and climate factors in Inner Mongolia was analyzed by using up to date vegetation map,statistics,modeling and spatial simulation of regional climatic factors under the support of GIS.The feasible climatic range of spatial distribution of plant communities was derived from overlaying vegetation map and climate maps.The results showed that the vegetation distribution was obviously in accordance with climate.On the one hand,all the types,not only zonal vegetation,but also mountain,sandy land and low land communities changed gradually from east to west due to the distance to oceans,with a zonal differentiation,Precipitation played an important role in determining this regulation.On the other hand,latitudinal replacement of plant communities occurred with the change of temperature from north to south.In addition,temperature was also the key factor controlling the spatial distribution of vegetation types,such as meadow,steppe,shrub and low land communities on the east and west sides of Daxinganling Mountains.
    Comparison of physiological characteristics of different ecotype plants
    TAI Peidong, GUO Shuhai, SONG Yufang, SUN Tieheng, LI Peijun, JIANG Shu
    2000, 11(2):  54-57. 
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    Studies on the responses of photosynthesis,leaf water content and stoma resistance of 4 different ecotype plants to water stresses showed that their mechanism of drought-resistance was different.Mesic plants limited water loss from transpiration by increasing their stoma resistance,while xeric plants decreased water loss by keeping the high concentration of cell protoplasm.The latter had a higher efficiency of keeping water than the former.The leaf water content and stoma resistance was decreased from mesic to xeric plants,while the net photosynthetic rate per unit leaf was increased, indicating the difference of physiological characteristics among different ecotype plants.
    Effect of cutting on vegetation composition and soil properties
    ZENG Xibo, LIU Gengling
    2000, 11(2):  58-61. 
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    Different cutting experiments were executed on well-grown natural Imperata cylindrica vegetation in red soil region.The biomass of every 6 years cutting was the highest,and the annual cut was the lowest.Annual cutting resulted in the highest total accumulative biomass in 6 years,with a total production of 399.1kg per plot.The species composition was also influenced by the length of cutting period.In the 6th year of experiment,the xylophyta biomass in the treatment of every 6 years cutting accounted for 41.5% of the total biomass,while the herb biomass in the treatment of annual cutting was 99.0% of the total.The length of cutting period also influenced the layer's development of soil profile and the physicochemical properties of soil.In comparing with the treatment of annual cutting, the soil bulk density in the treatment of every 6 years cutting was lower,and the contents of soil organic matter,total nitrogen,available phosphorus and available potassium were higher.
    Species composition and distribution of algae in semi desert algal crusts
    HU Chunxiang, LIU Yongding, SONG Lirong, HUANG Zebo
    2000, 11(2):  62-66. 
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    Twenty-two species of algae, including 10 Cyanophyta,4 Chlorophyta,6 Bacillariophyta and 2 Euglenophyta,were isolated and identified from the semi-desert algal crusts in Shapotou,Ningxia Autonomous Region.The relationship between algae and soil matrix was studied by grinding and superprobe,and the distribution of algal species in eight layers of crusts was examined under light and scanning electron microscopes.It was found that the algae exhibited a layer typed distribution in intermicron, and the layers of algal crust from surface to inner were in order of inorganic mineral protection layer(ca.0.02mm),alga enriched layer(0.02～2.5mm)and sparse algae layer(2.5～5.0mm).The filaments of algae were united with clay mineral by the polysaccharides and protein of their sheath,or extended directly into mineral granules to network and band sand and soil particles.
    Application of Quantitative Theory Ⅰ in commenting the relationship of forage species and weed species
    TU Xiuliang, LUO Shiming
    2000, 11(2):  67-69. 
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    Quantitative Theory Ⅰ was applied to evaluate the influence of managing measures on the relationship of pasture grass and weeds on two typical grasslands of south China.Grazing intensity and fertilizer dosage were the key factors affecting the dominance of pasture grass.The main weed species were E.odoratum,E.rubiginosum,H.perforata,I.anlindrica and E.annua.The suitable density of cattle was 1～4 cattle·hm-2,and the dosage of fertilizer application was 500～1000kg·hm-2 for superphoshate,and 150～250kg·hm-2 for KCl.
    Effect of modified ammonium bicarbonate on nitrification-denitrification process and NO and N2O emission
    HUANG Bin, CHEN Guanxiong, Oswald Van Cleemput
    2000, 11(2):  74-78. 
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    Compared with ammonium bicarbonate(AB),the effect of modified ammonium bicarbonate (MAB) on nitrification and denitrification processes and NO and N2O emissions in a clay soil (C soil) and a loam soil (L soil) was studied in laboratory (25℃ and 50% WFPS).The inhibition effect of DCD from MAB on nitrification was relatively small in C soil,but considerably great in L soil.Compared with AB,MAB extended 7 days and 33 days for retaining NH4+.During 15 days,the NO emission from C soil and L soil respectively accounted for 0.60% and 1.06% of applied N under AB application (100μg N·g-1 ),which were as 30 and 12 times as the N2O emission from corresponding soils.After applying MAB,the emission of NO from C soil and L soil decreased by 67% and 95%,and the emission of N2O decreased by 64% and 95%,respectively.After 39 days of aerobic incubation,then anaerobically flooded incubation with nitrate addition (200μg KNO3-N·g-1 ) for 7 days,the total loss of denitrification in MAB in L soil was 50% less,and N2O emission was 113% more than in AB in same soil.
    Genetic effect of panicle traits of intersubspecific crosses of rice ( Oryza sativa ) and its interaction with environment
    LIANG Kangjing
    2000, 11(2):  79-83. 
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    The models of genetic effects and genotype×environment interaction for Additive-Dominant-Additive×Additive epistasis were used to analyze the panicle traits of intersubspecific crosses of rice (Oryza sativa.) in different environments. It was found that significant additive, dominant and additive×additive epistatic effects and genotype×environment (GE) interaction were observed in main panicle length, spikelet density, primary branches, total lengths of primary and secondary branches, but the numbers of main panicle and secondary branches showed no significant additive×environment (AE) interaction and dominant×environment (DE) interaction.The seven traits studied were mainly controlled by dominant effects, but branches traits were more obviously affected by DE interaction. Heritabilities analysis showed that the general heritability in broad sense (HG2) was much larger than other heritabilities. To certain extent,the interaction heritabilities showed their effects in seven panicle traits tested. Heterotic prediction indicated a positive heterosis in all panicle traits except the numbers of primary and secondary branches. GE only influenced the expression extents of heterosis, but was not able to change their directions. According to the predicated genetic effects,IR66158-37,IR65600-85,Minhui63 and R669 were better than other parents in the tactics of breeding for improving panicle traits, because the progenies from these crosses always showed that panicle traits were slightly affected by environment.
    Insect community and its diversity in Mangrove forest at Yingluo Bay of Guangxi
    JIANG Guofang, YAN Zengguang, CEN Ming
    2000, 11(2):  96-99. 
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    The insect community and its diversity in mangrove forest at Yingluo Bay of Guangxi were studied in 1995～1996.The results show that there were 195 insect species in the mangrove area,dominated by Crematogaster rogenhoferi,Camponotus tokioensis and Dichocrocris chorophanta.The diversity of insect community was higher in the inside beach than in the middle and outside beaches.Tides and windstorms were the important factors that decided the community composition levels.The principal component affecting the diversity was the species evenness in the inside,middle and outside beaches.
    Vertical distribution and quantitative dynamics of dominant functional groups of arthropod community in rice fields and estimation of natural enemy effects
    HAO Shuguang, ZHANG Xiaoxi, CHENG Xianian
    2000, 11(2):  104-108. 
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    The study showed that Lycosid (wolf spider) mainly distributed in the basal part of rice plants,not as wide as we know in past.Tetragnathid did not limited in the upper part of plants,but might translate to middle or lower part when affected by insecticide.The relationship between the vertical distributions of top and basal species was not significant.Besides the amount of natural enemies,the spatial distribution characteristics of natural enemies and brownplanthopper,and the proportion of brownplanthopper to total preys of natural enemies were the factors affecting the role of natural enemies on the population dynamics of brownplanthopper in rice fields.A model to evaluate the effect of natural enemies to brownplanthopper was put forward,which included the messages of quantitative dynamics,spatial distribution and feeding characteristics of natural enemies,brownplanthopper and neutral insects.
    Evaluation of plant protectants against pest insects
    PANG Xiongfei, ZHANG Maoxin, HOU Youming, JIAO Yi, CEN Yijing
    2000, 11(2):  109-111. 
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    An interference index of population control (IIPC) was constructed for investigating the complex effects of plant protectants,including the effects of repelling insect pests away from the plant,deterring the egg laying of adults and the continuation of feeding, and causing death by toxicity. At the same time, indicated by IIPC, the alcohol extracts of some common plants, such as Eucalytus rubusta, Wedelia chinensis etc. and the neem oil gave very good results to protect the plant against Plutella xylostella. The D-C-Tron NR Petroleum Spray Oil (CALTEX) also gave an excellent effect to protect citrus against red mite. All the experiments show the important role of the repellent effect on the pests.
    Response of Capsicum frutescens metapopulation to simulated insect herbivorous behaviors
    LIU Chuanhua, ZHONG Zhangcheng, LU Junqiang
    2000, 11(2):  116-119. 
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    Based on the theory of metapopulation, this paper studied the response of different leaf-cutting Capsicum frutescens metapopulation to simulated short-term insect pestes during high temperature period in July.Variance analysis (ANOVA),principal component analysis(PCA)and plant growth analysis were applied.The result shows that C.frutescens had a strong compensatory ability.The number,dry weight and leaf area of old leaves decreased with increasing leaf cutting,but contrarily for new leaves.The total leaf number did not show any significant difference,but the total area and weight of leaves were significantly different,because of the influence of old leaves.The number,weight and lenght of branches were not significantly different with different treatments, and the number of fruits,flowers and flower buds also showed no significant difference.However,the difference of their dry weights was significant.It is practical to use number indexes,but not dry weight,leaf area and length for plant growth analysis in metapopulation,when the difference of dry weight between modulars is small.It is suggested that a certain degree of herbivory might be beneficial to the growth and fruit yield of C.frutescens during the high temperature period.
    Wetland ecosystems formation and its protection in Yellow River Delta
    MU Congru, YANG Linsheng, WANG Jinghua, HU Yuanman, LIN Hengzhang
    2000, 11(2):  124-127. 
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    Site investigation,satellite photo analysis and historic material analysis show that the vast neonatal wetlands in Yellow River Delta were created by high concentration sediment of the river and the land-sea evolution.Affected by the regional climate,landform,geological deposition,soil,vegetation and their interactions,the wetlands covered 4.5×105hm2, 6.84 ×104hm2 of which were artificial wetlands.The wetland ecosystems changed with the waving of the Yellow River Mouth and the land development in the Delta area.From ocean to land,the sublittoral aquatic wetland,eulittoral wetland,eplittoral salt wetland,bulrush-quitch wetland,meadow wetland and land agroecosystem were developed.The wetland ecosystems had abundant biological resources,including 1524 wild animals,300 birds and 1040 fishes,which were changed recently by the oil development and affected by the interruption of Yellow River.Wetland protection should be strengthened in resources utilization.
    Landscape heterogeneity of urban vegetation in Guangzhou
    LI Zhen, WANG Lirong, GUAN Dongsheng
    2000, 11(2):  128-131. 
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    Seven indexes were used to study the landscape heterogeneity of vegetation in Guangzhou City.The results show that the patch density was 11.8 patches·km-2 and the line corridor density was 1.87km·km-2.In old urban area,the vegetation landscape was characterized by small patches,heavy fragmentation,high diversity and random distribution,showing a highly heterogeneous spatial pattern, while in new urban area,the vegetation landscape was characterized by big patches and even distribution.Therefore,when the size of vegetation area was the same,the even distribution of vegetation could improve the landscape heterogeneity and make the ecological function more effective.
    Nutrient retranslocation in fine roots of Cunninghamia lanceolata,Alnus cremastogyne and Kalopanax septemlobum in the mixed plantations-a pilot study
    LIAO Liping, GAO Hong, YU Xiaojun, HAN Shijie
    2000, 11(2):  161-164. 
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    Comparison of N,Pand Kconcentrations in live and dead fine roots of Cunninghamia lanceolata,Alnus cremastogyne and Kalopanax septemlobum showed that the fine roots of A. cremastogyne had a stronger ability of Nretranslocation than K.septemlobum's, but no N translocation occurred in C.lanceolata's. P retranslocation could be found in the fine roots of the all test tree species except C.lanceolata.As for K,it could translocate from fine roots to tree bodies of all these tree species before senescence.Based on the analysis on the difference of N,P,and K concentrations in live fine roots of each pair of tree species in the mixtures,it was suggested that N and K could respectively transfer from the root system of A.cremastogyne and K. septemlobum to the fine roots of C.lanceolata,and the mechanism could be clarified through exploring the ecological process of root-soil interface.
    Distribution pattern and its dynamics of Taxus chinensis var. mairei population on Yunbaoshan Mountain.
    LI Xiankun, HUANG Yuqing, SU Zongming
    2000, 11(2):  169-172. 
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    Field data were sampled by the method of contiguous grid quadrate,and t-test of v/m ratio,negative binomial parameter,Green's index,Cassie's index,dispersion index,clumping index,mean crowding index and patchiness index were used to analyse the distribution pattern and its dynamics of Taxus chinensis var. mairei population.The result shows that the distribution pattern was clustering.From sapling to grown up tree,the clustering degree was decreasing,while the big trees had a random distribution.
    Impact of salinity on accumulation of several metal elements in Bruguiera gymnorrhiza seedlings and Ca effect
    LI Yinpeng, LIN Peng
    2000, 11(2):  177-180. 
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    The contents of K,Ca,Na and Mg in different organs of Bruguiera gymnorrhiza seedlings cultured in sand bases with solutions of 400 mmol·L-1 NaCl and different concentrations of CaCl2 were determined.In the treatment of 400 mmol·L-1 NaCl,Na was largely accumulated in organs,which caused the decrease of K/Na and Ca/Na,and decreased dry matter accumulation in seedlings.Supplemental CaCl2 decreased the accumulation of Na in seedlings,increased the ratios of K/Na and Ca/Na and the accumulation of dry matter,and thereby,mitigated salt stress.The suitable concentration of CaCl2 was 10～15 mmol·L-1.It was concluded that B.gymnorrhiza seedlings cultured at high salinity accumulated more metal ions,which enhanced osmotic adjustment of plants,and kept highly selective absorption of K/Na.These characteristics are the main physiological mechanisms of the adaptation of B.gymnorrhiza to high salinity in estuary and coast,while suitable Ca/Na in soil is one of the important causes that B.gymnorrhiza can survive and regenerate in high salinity coast.
    Caloric values and ash contents of some mangrove woods
    LIN Yiming, LIN Peng, WANG Tong
    2000, 11(2):  181-184. 
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    The caloric values and ash contents of some mangrove woods in Dongzhai Harbor Mangrove Forest Reserve of Hainan Province were determined in Summer,and the changes of the caloric value of Kandelia candel woods at different latitudes were studied.The ash content of mangrove woods was low,ranging from 2.43% to 5.17%;and their gross and ash-free caloric values ranged from 17.23 kJ·g-1 to 19.21kJ·g-1 and from 17.70kJ·g-1 to 20.10kJ·g-1,respectively. Sonneratia apetala wood had the lowest gross and ash-free caloric values.The caloric value of Kandelia candel wood decreased with increasing latitude in Summer.
    Distribution patterns of shoots,flowers and seeds in Ginkgo biloba canopy and their relationships
    WANG Jian, WEI Gang
    2000, 11(2):  185-189. 
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    The distribution patterns of shoots, flowers and seeds in the canopy of 14 years old engrafted Ginkgo biloba and their relationships were investigated with stratification method.The result shows that long shoots,short shoots,bearing shoots and flowers uniformly distributed in the central section of canopy.From the top to the bottom, the average age and the divaricating angle of long shoots increase 51.3% of the seeds distributed in 180～320cm layer from the ground.The number of shoots, flowers and seeds in different canopy layers was closely correlated.
    Dynamics of phenolics content of Chinese fir stump-roots and the rhizosphere soil and it's allelopathy
    HUANG Zhiqun, LIAO Liping, WANG Silong, LUI Yingdi
    2000, 11(2):  190-192. 
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    Studies on the releasing pattern of phenolics during the decomposition of Chinese fir stump root and on its allelopathy show that the phenolics contents in stump-roots decreased with their decomposition.Roots had a higher content of phenolics than heart stumps,and edge stumps had the least.The phenolics was released during decomposition,and accumulated in the soils around stump-roots.Pot culture experiment showed that phenolics affected the germination of Chinese fir seeds.The correlation analysis between the density of Chinese fir stump-root and the tree height and base diameter (BD) of its saplings proved that Chinese fir stump-roots had a negative impact on the growth of the next generation of Chinese fir plantations.It is suggested that the traditional operation of Chinese fir plantations should be reformed,and the stump-roots should be cleared from woodland before reforestation.
    Articles
    Effect of different watering and fertilization on Nutilization efficiency
    HE Hua, ZHAO Shiwei, CHEN Guoliang
    2000, 11(2):  235-239. 
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    The comprehensive effects of the timing of watering and N and K fertilization(D),amount of irrigated water(W),and application rates of chemical N and K fertilizers,and farm manure(M) were studied by the design of orthogonal regression rotation with five factors and five levels under dry greenhouse condition.The N utilization efficiency of potato was in order of N>W>D>M>K.Under different application rates of W,N,K and M,the N utilization efficiency was significantly increased with optimum timing of watering and fertilization.When the application rate was low,the timing should be earlier,while it was high,the timing should be later.High application rates of W and N resulted in the best interaction effect,with 57.83% of N utilization efficiency;moderater W and N or low W and N had 29.17～40.99% of efficiency;and high W and low N or low W and high N resulted in the lowest efficiency,with 22.87% and 22.51%,respectively.
    Leaching loss of nitrate from semiarid area agroecosystem
    LI Shiqing, Li Shengxiu
    2000, 11(2):  240-242. 
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    A 6 years lysimeter experiment shows that an obvious nitrate leaching even occurred in semiarid area agroecosystem.The leaching loss was positively related to precipitation,and had a signficant difference among years with different precipitation.The application rate of N fertilizers determined the amount of leaching loss,but no obvious difference was found between urea and ammonium bicarbonate.Different depth of soil had different water storage,and therefore, had different leached amounts.Summer fallowing could increase the potential nitrate leaching loss.
    Determination of tannin in cotton plant
    WU Yuqing, GUO Yuyuan
    2000, 11(2):  243-245. 
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    Three methods were used to determine the tannins content in cotton plant tssues.The tannin content in different organs and terminal leaves of four cotton varieties at different growth stages determined by the Folin's assay was nearly two folds as much as that determined by acid butanol assay,indicating that the Folin's assay only offers the total phenol content,but is not suitable for determining the content of condensed tannin in cotton.There was no significant difference between the results of vanillin assay and acid butanol assay,and hence,it is feasible to use vanillin assay to test the tannin content in cotton.Determinations at boll stage showed that the content of condensed tannin in calyx,boll shell and leaf was rather high,generally up to 5～10%,while that in petal,stigma,ovary and inner boll was lower(about 2%).The condensed tannin content in terminal leaf continually increased from seedling(<1%)to boll stage(10% or so),indicating that the increased tannin content is closely related to the maturity,decrepitude and lignification of cotton tissues.
    Articles
    Adaptation of transgenic strains of insect-resistance cotton to different ecological environments
    LIN Yi
    2000, 11(2):  246-248. 
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    Seven transgenic strains of insect-resistance cotton,WH1,WH2,WH3,WH4,WH5,WH6 and BG2,and one common strain Simian-3 (CK) were selected to investigate their adaptation to insect-resistance and yield trait at 10 different sites.The results show that all transgenic strains had a strong resistance to bollworm(Helicoverpa armigera) and pink bollworm (Pectinophora gossypiella),with a high stability and no difference in 10 sites,but the yield trait was significantly influenced by environmental factors.The interaction between strains and sites was significant. In comparison with CK,WH6 and BG2 had a good insect resistance and high fiber yield,and could be applied in practice.
    Isolation and selection of strains used to degrade organic chlorine pesticides and application effects
    FANG Ling
    2000, 11(2):  249-252. 
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    With the organic chlorine pesticides (666, DDT) as sole carbon resources, three strains, No.153 (Bacillus), No.411 (Achromobacter) and No.512 (Pseudomonas), which can degrade 666 (BHC), were isolated and selected in Tonomura culture medium. The degradation rates of these strains were 59.6%, 56.9% and 56.0% for total amount of 666, and 55.9%, 57.6% and 56.9% for β-666, respectively. The other strains, No.288 (Alcaligenes), No.410 and No.411 (Achromobacter) to degrade DDT were also obtained. The degradation rates of the strains were 59.0%, 47.5% and 45.1% for total amount of DDT, and 59.9%, 57.6% and 49.6% for PP'-DDT, respectively. The degradation effects of the mixtures of the isolated strains in pot and field experiments were similar to those of the pure culture, indicating it is a feasible measure to apply the mixture of strains to degrade residual pesticides in fields.
    Interaction of Se and S forms in rhizospheric soil and their absorption by tobacco
    MA Youhua, DING Runxing, ZHANG Jizhen, ZHU Weiming
    2000, 11(2):  253-257. 
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    Pot experiment with tobacco shows that the amount of total,solube,exchangeable and organic Se in rhizospheric soil appeared depletory,while that of total,adsorbed and organic S appeared enriched.The influence of added S on Se depletion depended on the level of Se application,and that of added Se on S enrichment depended on the rate of S applicagtion.In the absence of added Se,the addition of S decreased the depletion of several Se forms;while in its presence,the reverse result was obtained.The addition of Se increased the enrichment of total S when the S was not added.With S application,the added Se reduced the enrichment of total S.At early stage,teh Se content of tobacco was mainly influenced by the soluble Se in rhizospheric soil,while the accumulated amount of Se in tobacco was also influenced by exchangeable,organic and acid soluble Se.The S content in the aboveground part of tobacco at its early stage was mainly influenced by soluble and organic S in the rhizosphere.
    Articles
    Nutrient retranslocation in fine roots of Cunninghamia lanceolata,Alnus cremastogyne and Kalopanax septemlobum in the mixed plantations-a pilot study
    LIAO Liping, GAO Hong, YU Xiaojun, HAN Shijie
    2000, (2):  161-164. 
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    Comparison of N,Pand Kconcentrations in live and dead fine roots of Cunninghamia lanceolata,Alnus cremastogyne and Kalopanax septemlobum showed that the fine roots of A. cremastogyne had a stronger ability of Nretranslocation than K.septemlobum's, but no N translocation occurred in C.lanceolata's. P retranslocation could be found in the fine roots of the all test tree species except C.lanceolata.As for K,it could translocate from fine roots to tree bodies of all these tree species before senescence.Based on the analysis on the difference of N,P,and K concentrations in live fine roots of each pair of tree species in the mixtures,it was suggested that N and K could respectively transfer from the root system of A.cremastogyne and K. septemlobum to the fine roots of C.lanceolata,and the mechanism could be clarified through exploring the ecological process of root-soil interface.
    Community characteristics of rare trees at Dalaoling of Three Gorge reservoir area in western Hubei Province
    CAI Sheng, LIU Xuequan, ZHANG Jialai
    2000, (2):  165-168. 
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    The quantitative characteristics,plant frequency in layers and species diversity of David involucrata var. vilnoriniara,Euptlea pleiosperma,Stewartia sinensis and Pterostyrax psilophtila communities at Dalaoling National Forest Park Reserve of Yichang were studied qualitatively and quantitatively.The community composition and structure were made clear,the succession courses and stages of the communities were revealed,and the role of these rare trees on the succession course of communities and the cause of being in imminent danger were analyzed,which provided a theoretical basis for protecting the rare trees in the Three-Gorge reservoir area.
    Articles
    Distribution pattern and its dynamics of Taxus chinensis var. mairei population on Yunbaoshan Mountain.
    LI Xiankun, HUANG Yuqing, SU Zongming
    2000, (2):  169-172. 
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    Field data were sampled by the method of contiguous grid quadrate,and t-test of v/m ratio,negative binomial parameter,Green's index,Cassie's index,dispersion index,clumping index,mean crowding index and patchiness index were used to analyse the distribution pattern and its dynamics of Taxus chinensis var. mairei population.The result shows that the distribution pattern was clustering.From sapling to grown up tree,the clustering degree was decreasing,while the big trees had a random distribution.
    Quantitative characteristics of rare and endangered Castanopsis kawakamii population
    WU Chenzhen, HONG Wei, CHEN Hui, LIU Jinfu, HE Dongjin, LIN Chenlai
    2000, (2):  173-176. 
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    In this paper,a new self adaptive model for population growth,i.e. S= exp (αln2(1+ce-rt)+βln (1+ce-rt)+γ) was established,which combined Logistic,Smith,Gompertz,Cui-Lawson,Zhang-Logistic and Liu-Logistic models.Estimations with genetic algorithm showed that the new model was more suitable than other models to simulate the actual growth trend of Castanopsis kawakamii population.
    Articles
    Impact of salinity on accumulation of several metal elements in Bruguiera gymnorrhiza seedlings and Ca effect
    LI Yinpeng, LIN Peng
    2000, (2):  177-180. 
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    The contents of K,Ca,Na and Mg in different organs of Bruguiera gymnorrhiza seedlings cultured in sand bases with solutions of 400 mmol·L-1 NaCl and different concentrations of CaCl2 were determined.In the treatment of 400 mmol·L-1 NaCl,Na was largely accumulated in organs,which caused the decrease of K/Na and Ca/Na,and decreased dry matter accumulation in seedlings.Supplemental CaCl2 decreased the accumulation of Na in seedlings,increased the ratios of K/Na and Ca/Na and the accumulation of dry matter,and thereby,mitigated salt stress.The suitable concentration of CaCl2 was 10～15 mmol·L-1.It was concluded that B.gymnorrhiza seedlings cultured at high salinity accumulated more metal ions,which enhanced osmotic adjustment of plants,and kept highly selective absorption of K/Na.These characteristics are the main physiological mechanisms of the adaptation of B.gymnorrhiza to high salinity in estuary and coast,while suitable Ca/Na in soil is one of the important causes that B.gymnorrhiza can survive and regenerate in high salinity coast.
    Caloric values and ash contents of some mangrove woods
    LIN Yiming, LIN Peng, WANG Tong
    2000, (2):  181-184. 
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    The caloric values and ash contents of some mangrove woods in Dongzhai Harbor Mangrove Forest Reserve of Hainan Province were determined in Summer,and the changes of the caloric value of Kandelia candel woods at different latitudes were studied.The ash content of mangrove woods was low,ranging from 2.43% to 5.17%;and their gross and ash-free caloric values ranged from 17.23 kJ穏-1 to 19.21kJ穏-1 and from 17.70kJ穏-1 to 20.10kJ穏-1,respectively. Sonneratia apetala wood had the lowest gross and ash-free caloric values.The caloric value of Kandelia candel wood decreased with increasing latitude in Summer.
    Distribution patterns of shoots,flowers and seeds in Ginkgo biloba canopy and their relationships
    WANG Jian, WEI Gang
    2000, (2):  185-189. 
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    The distribution patterns of shoots, flowers and seeds in the canopy of 14 years old engrafted Ginkgo biloba and their relationships were investigated with stratification method.The result shows that long shoots,short shoots,bearing shoots and flowers uniformly distributed in the central section of canopy.From the top to the bottom, the average age and the divaricating angle of long shoots increase 51.3% of the seeds distributed in 180～320cm layer from the ground.The number of shoots, flowers and seeds in different canopy layers was closely correlated.
    Dynamics of phenolics content of Chinese fir stump-roots and the rhizosphere soil and it's allelopathy
    HUANG Zhiqun, LIAO Liping, WANG Silong, LUI Yingdi
    2000, (2):  190-192. 
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    Studies on the releasing pattern of phenolics during the decomposition of Chinese fir stump root and on its allelopathy show that the phenolics contents in stump-roots decreased with their decomposition.Roots had a higher content of phenolics than heart stumps,and edge stumps had the least.The phenolics was released during decomposition,and accumulated in the soils around stump-roots.Pot culture experiment showed that phenolics affected the germination of Chinese fir seeds.The correlation analysis between the density of Chinese fir stump-root and the tree height and base diameter (BD) of its saplings proved that Chinese fir stump-roots had a negative impact on the growth of the next generation of Chinese fir plantations.It is suggested that the traditional operation of Chinese fir plantations should be reformed,and the stump-roots should be cleared from woodland before reforestation.
    Energy distribution of Phyllostachys pubescens ecosytem in north Fujian
    LAN Bin, HE Dongjin, WU Chengzhen, HONG Wei
    2000, (2):  193-195. 
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    Based on the data obtrained from 40 Phyllostachys pubescens plots in Jianou City of Fujian Province,the distribution of energy was studied in this paper.The results showed that the energy contained in stems,branches and leaves,and underground parts of P.pubescens ecosystem were 4.2322?108kJ穐m-2,0 9230?108kJ穐m-2 and 1.7643?108kJ穐m-2,accounting for 61.32%,13.11% and 25.57% of the total energy respectively.
    Utilizable value of wild economic plant resource-acorn kernel
    HE Ruiguo, WANG Kangming, WANG Yulian, XIONG Tongan
    2000, (2):  196-198. 
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    Peking whites breeding hens were selected. Using true metabolizable energy method (TME) to evaluate the available nutritive value of acorn kernel, while maize and rice were used as control. The results showed that the contents of gross energy (GE), apparent metabolizable energy (AME), true metabolizable energy (TME) and crude protein (CP) in the acorn kernel were 16.53mg穔g-1, 11.13mg穔g-1, 11.66mg穔g-1 and 10.63%, respectively. The apparent availability and true availability of crude protein were 45.55% and 49.83%. The gross content of 17 amino acids, essential amino acids and semiessential amino acids were 9.23% and 4.84%. The true availability of amino acid and the content of true available amino acid were 60.85% and 6.09%. The contents of tannin and hydrocyanic acid were 4.55% and 0.98% in acorn kernel. The available nutritive value of acorn kernel is similar to maize or slightly lower, but slightly higher than that of rice. Acorn kernel is a wild economic plant resource to exploit and utilize but it contains higher tannin and hydrocyanic acid.
    Effect of nitrogen on water use efficiency of apple tree
    QU Guimin, WANG Hongxia, SHU Huairui
    2000, (2):  199-201. 
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    This paper studied the effect of nitrogen fertilizer on water use efficiency(WUE) and relevant parameters of two years old potted apple trees(Starkrimson/ Malus hupenensis) under different soil moisture condition.The results showed that under adequate soil moisture,WUE was decreased with increasing application of nitrogen fertilizer.Nitrogen fertilizer application resulted in an increase of stomatal conductane.Consequently,the transpiration rate was increased more than photosynthetic rate did.Under soil drought,the WUE of plants applied with nitrogen fertilizer was apparently higher than that of control.The WUE value was in the order of high N>medium N>low N.The improvement of WUE was due to the increase of mesophyll capacity,which led to the promotion of photosynthesis.
    Wind tunnel experiment on canopy structural parameters of isolated tree and wind velocity field characters nearby
    GUAN Dexin, ZHU Tingyao
    2000, (2):  202-204. 
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    The canopy structural parameters(porosity β and permeability α) of isolated tree,and the wind velocity field character nearby were analyzed by wind tunnel experiment.The results show that α and β fitted the function of α=β0.6,and the wind velocity nearby decreased in ellipsoid contour. The contour increased with increasing tree height and canopy width,and decreased with increasing permeability (or porosity).The isotach became the shape of ellipses or elliptic segments in horizontal and vertical plans.
    Horizontal thermal characteristics at forest edge in calm tropical region of China
    ZHANG Yiping, MA Youxin, LIU Yuhong, ZHANG Keying
    2000, (2):  205-209. 
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    The temperature measurement at south west-facing edge of a rubber forest was conducted in a calm tropical region of Xishuangbanna,Yunnan,China in January 1998,and the daytime thermal characteristics and their time-space variations nearby the edge of the rubber forest were discussed.There was an obviously thermal effect at forest edge.The depth of edge influence on soil surface temperature was up to 13m from the edge into the forest.Soil surface temperature reached its highest at 4.5 m outside the forest.The highest air temperature occurred at 0 m of the edge.The heat transfer nearby the edge was quite different in number and in direction.Outside the forest,the heat was transferred from ground to air on almost daytime,while at interior of forest,was opposite after the noon.The heat was transferred from the rubber canopy to the ground.At the forest edge,such variation was complex,depended mainly on location and time.
    Effect of unsymmetrical cutting along both river slopes on rainstorm-runoff process
    CHEN Junfeng, PEI Tiefan, TAO Xiangxin, LIU Sidan, NIU Lihua
    2000, (2):  210-214. 
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    A simulation experiment was conducted to compare the effect of cutting and no-cutting at both slopes along a river on the rainstorm run-off in catchment,and a model was constructed.The results showed that the appearance of outflow and peak flow of surface run-off was later on forest slope than on forest-cutting slope.On forest slope,the duration was prolonged,and the peak flow and surface runoff were lower.These effects were more obvious as the slope gradient was bigger.When rain intensity was 1.98mm穖in-1 and rainfall was 108.8mm,the peak flow and the total runoff on both forested slopes of gradient 15皐as 5% and 4% less than that on the cutting slopes,respectively.
    Effect of land management in winter crop season on seasonal variations of CH4 emissions from rice paddy soils
    XU Hua, CAI Zucong, LI Xiaoping, Haruo Tsuruta
    2000, (2):  215-218. 
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    A pot experiment in greenhouse was carried out to study seasonal variations of CH4 fluxes from rice paddy soils and the effect of land management in winter crop season on the seasonal variations. The results showed that four emission peaks occurred respectively 13 days after flooding and 7, 40, 91 days after rice transplanting, and CH4 emission amounts during the first 30 days after flooding accounted for as high as 67.5%, 35.5% and 33.3% of the total emission amounts during the observing period of 133days for treatments with dry fallow but rice straw being applied just before flooding, alfalfa, and flooded fallow in winter crop season. However, for treatments with dry fallow but rice straw being applied before winter crop cultivating and winter wheat in winter crop season, CH4 emission amounts during the first 50 days after flooding just accounted for 0.27% and 6.74 of the total emission amounts during the observing period, and CH4 fluxes thereafter were also very small. Difference in the seasonal variation patterns of soil Eh due to land management in winter crop season was the main reason why seasonal variation patterns of CH4 fluxes from different treatments were different.
    Yield increasing and water saving effect under different soil fertility improvements in wheat-corn intercropping field in Huabei Plain
    ZHANG Zhongxue, WEN Jinxiang, WU Wenliang
    2000, (2):  219-222. 
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    Water resource in agriculture in Huabei Plain has been increasingly reduced in recent years.In order to reduce water evaporation and improve water utilization efficiency, the field experiment on water saving under different soil fertility improvements was carried out in Huantai county,Shandong Province.The result showed that straw incorporation and organic fertilizer application could increase yield and save water clearly.Under the same amount of irrigation(250mm),the field with all corn and wheat straw incorporation had a higher yield of 885kg穐m-2 than the field without straw incorporatiion, and a higher water efficiency of 3.13.The field with all corn and wheat straw incorporation and organic fertilizer application had a higher yield of 1875kg穐m-2 than the comparing field, with a higher water efficiency of 3.60.The field with wheat straw incorporation had a higher yield of 675kg穐m-2 than the comparing field,with a higher water efficiency of 3.24.The field with wheat straw incorporation and organic fertilizer application had a higher yield of 1200kg穐m-2 than the comparing field, with a higher water efficiency of 3.28.
    Rational range and optimum proportion of energy input in farmland
    YIN Jun, ZHOU Naijian, GAO Zhiqiang, YANG Wude, MIAO Guoyuan
    2000, (2):  223-227. 
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    There exists a rational range of artificial supplemental energy inputs in fields.In the range,the inputs can improve the yield and the output/input ratio.The rational range of energy input in total energy output is bigger than that in the output/input ratio.It is bigger in low yield fields than high yield fields,which suggests that increasing artificial supplemental energy input can increase the production of low yield fields as same as high yield fields.In the rational range of energy input,there exist high efficient lines in water and fertilizer inputs.The highest efficiency occurs when the rational inputs of water and fertilizer occur in these two lines.There also exist optimum lines of energy and economy input proportions.In the two lines,the proportions of energy and economy output/input of water and fertilizer inputs are the highest,which are the optimum of water and fertilizer inputs.Water and fertilizer may replace each other for equal yields,but would result in a decrease in the output/input ratio.
    Boron balance in agroecosystem on brown red soil of south Hubei Province
    CAO Cougui, CAI Chongfa, ZHANG Guangyuan, WANG Yunhua
    2000, (2):  228-230. 
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    Five sequential cropping systems including rape/soybean rice, wheat/watermelon rice, rape/corn soybean, wheat sesame and soybean sesame, were selected study the boron balance in agroecosystem on brown red soil of south Hubei Province.The results show that the main output of boron was runoff and leaching,which accounted for 48～53% and 41% of the total respectively,while the output by products accounted for 3.4～10.1%.The main inputs were from rainfall,irrigation,fertilization seeds and seedlings,and natural return.
    Soil nitrogen and organic matter losses under water erosion
    ZHANG Xingchang, SHAO Mingan
    2000, (2):  231-234. 
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    The results of artificial water-scoured experiment show that with the increase of water-scoured intensity,the losses of nitrate and ammonium in runoff,and those of organic matter and total N in sediment increased greatly,while the enrichment ratios of organic matter and total N in sediment reduced correspondingly.When the soils in gully hilly loess region were fertilized with same amount of NH4NO3,the ammonium and nitrate loss in runoff was respectively 0.9～3.5% and 8.2～19.7% of the application amount. Nitrate mainly lossed in runoff, not in sediment.The correlation coefficient of soil erosion module,organic matter and total N loss with>20μm soil aggregates was-0.8935,-0.7928 and-0.8151,respectively.The content of>20μm soil aggregates could be used as an index to differentiate the soil organic matter and total N loss.
    Articles
    Effect of different watering and fertilization on Nutilization efficiency
    HE Hua, ZHAO Shiwei, CHEN Guoliang
    2000, (2):  235-239. 
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    The comprehensive effects of the timing of watering and N and K fertilization(D),amount of irrigated water(W),and application rates of chemical N and K fertilizers,and farm manure(M) were studied by the design of orthogonal regression rotation with five factors and five levels under dry greenhouse condition.The N utilization efficiency of potato was in order of N>W>D>M>K.Under different application rates of W,N,K and M,the N utilization efficiency was significantly increased with optimum timing of watering and fertilization.When the application rate was low,the timing should be earlier,while it was high,the timing should be later.High application rates of W and N resulted in the best interaction effect,with 57.83% of N utilization efficiency;moderater W and N or low W and N had 29.17～40.99% of efficiency;and high W and low N or low W and high N resulted in the lowest efficiency,with 22.87% and 22.51%,respectively.
    Leaching loss of nitrate from semiarid area agroecosystem
    LI Shiqing, Li Shengxiu
    2000, (2):  240-242. 
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    A 6 years lysimeter experiment shows that an obvious nitrate leaching even occurred in semiarid area agroecosystem.The leaching loss was positively related to precipitation,and had a signficant difference among years with different precipitation.The application rate of N fertilizers determined the amount of leaching loss,but no obvious difference was found between urea and ammonium bicarbonate.Different depth of soil had different water storage,and therefore, had different leached amounts.Summer fallowing could increase the potential nitrate leaching loss.
    Determination of tannin in cotton plant
    WU Yuqing, GUO Yuyuan
    2000, (2):  243-245. 
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    Three methods were used to determine the tannins content in cotton plant tssues.The tannin content in different organs and terminal leaves of four cotton varieties at different growth stages determined by the Folin's assay was nearly two folds as much as that determined by acid butanol assay,indicating that the Folin's assay only offers the total phenol content,but is not suitable for determining the content of condensed tannin in cotton.There was no significant difference between the results of vanillin assay and acid butanol assay,and hence,it is feasible to use vanillin assay to test the tannin content in cotton.Determinations at boll stage showed that the content of condensed tannin in calyx,boll shell and leaf was rather high,generally up to 5～10%,while that in petal,stigma,ovary and inner boll was lower(about 2%).The condensed tannin content in terminal leaf continually increased from seedling(<1%)to boll stage(10% or so),indicating that the increased tannin content is closely related to the maturity,decrepitude and lignification of cotton tissues.
    Articles
    Adaptation of transgenic strains of insect-resistance cotton to different ecological environments
    LIN Yi
    2000, (2):  246-248. 
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    Seven transgenic strains of insect-resistance cotton,WH1,WH2,WH3,WH4,WH5,WH6 and BG2,and one common strain Simian-3 (CK) were selected to investigate their adaptation to insect-resistance and yield trait at 10 different sites.The results show that all transgenic strains had a strong resistance to bollworm(Helicoverpa armigera) and pink bollworm (Pectinophora gossypiella),with a high stability and no difference in 10 sites,but the yield trait was significantly influenced by environmental factors.The interaction between strains and sites was significant. In comparison with CK,WH6 and BG2 had a good insect resistance and high fiber yield,and could be applied in practice.
    Isolation and selection of strains used to degrade organic chlorine pesticides and application effects
    FANG Ling
    2000, (2):  249-252. 
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    With the organic chlorine pesticides (666, DDT) as sole carbon resources, three strains, No.153 (Bacillus), No.411 (Achromobacter) and No.512 (Pseudomonas), which can degrade 666 (BHC), were isolated and selected in Tonomura culture medium. The degradation rates of these strains were 59.6%, 56.9% and 56.0% for total amount of 666, and 55.9%, 57.6% and 56.9% for β-666, respectively. The other strains, No.288 (Alcaligenes), No.410 and No.411 (Achromobacter) to degrade DDT were also obtained. The degradation rates of the strains were 59.0%, 47.5% and 45.1% for total amount of DDT, and 59.9%, 57.6% and 49.6% for PP'-DDT, respectively. The degradation effects of the mixtures of the isolated strains in pot and field experiments were similar to those of the pure culture, indicating it is a feasible measure to apply the mixture of strains to degrade residual pesticides in fields.
    Interaction of Se and S forms in rhizospheric soil and their absorption by tobacco
    MA Youhua, DING Runxing, ZHANG Jizhen, ZHU Weiming
    2000, (2):  253-257. 
    Asbtract ( 1379 )   PDF (607KB) ( 263 )  
    Pot experiment with tobacco shows that the amount of total,solube,exchangeable and organic Se in rhizospheric soil appeared depletory,while that of total,adsorbed and organic S appeared enriched.The influence of added S on Se depletion depended on the level of Se application,and that of added Se on S enrichment depended on the rate of S applicagtion.In the absence of added Se,the addition of S decreased the depletion of several Se forms;while in its presence,the reverse result was obtained.The addition of Se increased the enrichment of total S when the S was not added.With S application,the added Se reduced the enrichment of total S.At early stage,teh Se content of tobacco was mainly influenced by the soluble Se in rhizospheric soil,while the accumulated amount of Se in tobacco was also influenced by exchangeable,organic and acid soluble Se.The S content in the aboveground part of tobacco at its early stage was mainly influenced by soluble and organic S in the rhizosphere.
    Cu, Co and Se nutritive value of compound trace elements controlled release boluses for grazing ruminants
    HE Ruiguo, WANG Shenglin, YAO Yanping, WANG Yulian
    2000, (2):  258-260. 
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    Twenty cattle with the similar old and weight were randomly divided into two groups for 135d,while twenty white goats were randomly divided into two groups for 60d. Each group consisted of ten animals, and the ratio of male and female was same. Each of animals in one group was administered an initial bolus, used as treatment group. In the other group, animals were not administered the bolus, used as control group. In the cattle feeding experiment, five cattle of each group was supplemented feed, and the other five cattles were not supplemented feed. In the goat feeding experiment, all of goats were grazing, and not supplemented feed. At the end of goat feeding experiment, three goats of each group were randomly selected to slaughter. Liver, kidney, spleen, muscle, heart, blood and matter in the rumen were collected to assay for Cu, Co and Se. The results showed that the average daily gain of cattle supplemented and no supplemented feeds in the administered and no administered group was 483.00g, 302.83g, 445.84g and 282.23g, respectively. There had significantly difference between the administered group and no administered group(p<0.05). The average daily gain of goats in the administered and no administered groups was 68.83g and 50.67g,and significant difference between the two groups (p<0.01). Administering the boluses improved the contents of Cu, Co and Se in the tissues of goats, significantly.
    Flood prevention function of Panjin wetland at Liaohe delta
    ZHAO Yi, LI Yuehui, CAO Yu
    2000, (2):  261-264. 
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    This paper discussed the character of flood,the change of flood disasters and the flood prevention function of Panjin wetland at Liaohe delta.According to the hydrogeological characters of Panjin wetland and its landscape function in flood prevention and disaster reduction,the Panjin wetland was divided into key prevention area,flood ground stored area,flood discharged area,emergent flood divresion area,and flood prevention and draining area,which might be a reference to the planning of local development.
    Ecological planning and designing in agricultural landscapes
    WANG Yanglin, HAN Dang
    2000, (2):  265-269. 
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    Based on the therories of landscape ecology,this paper discussed the principles and methods of ecological planning and designing in agricultural landscapes.It is suggested that the ecological planning and designing in agricultural landscapes became an important applied field of landscape ecology,due to the characteristics of microspatiality,and correlation and integration involved problems.The Zhuolu basin,located in the semiarid region of northwest Hebei Province was chosen as a case study.
    Preliminary study on purification function of reed wetland for nutrients from land sources
    QU Xiangrong, JIA Hongyu, ZHANG Hairong, LI Xiuzhen, LI Peijun
    2000, (2):  270-272. 
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    The preliminary study on purification function of reed wetland for nutrients from land sources were conducted by irrigation channels and lysimeters.The results show that the purification rates for N, P and CODcr are from 41.7%～64.71% in the channels and 60.0%～75.92% in the lysimeters.The contents of N and P reached the national second level standards of sea water after filtration by lysimeters.By harvest, the good recycle between wetland and land is formed without accumulation.
    Effect of initial population density on resting egg formation of rotifer Brachionus calyciflorus
    XI Yilong, HUANG Xiangfei
    2000, (2):  273-276. 
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    With the method of population accumulative culture, the effect of initial population density on the formation of resting eggs of freshwater rotifer(Brachionus calyciflorus), and on the rates of mictic female and fertilization was studied.During 11 days culture,the productivity and the formation efficiency of resting eggs,and the mean rate of mictic female were the biggest when the initial population density was 1.0～10.0 ind·ml-1,second by the density of 20.0 ind·ml-1,and the lowest by the density of 50.0 ind·ml-1.There was no significant effect of initial population density on the fertilization rate.Statistical analysis on maximum formation efficiency of resting eggs,their emergence and productivity showed that when the production of resting eggs was large scaled proceeded,the feasible initial population density should be 10.0 ind·ml-1,and the corresponding time should be 6 days to obtain a higher yield of resting eggs and a higher formation efficiency.
    Prediction of bioconcentration factors of organic compounds in fish by molecular connectivity indices and function correction factors
    LU Xiaoxia, TAO Shu, HU Haiying
    2000, (2):  277-282. 
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    Studies on the prediction models of bioconcentration factors(BCF) of 239 organic compounds showed that the BCFs of polar organic compounds could not be accurately predicted solely by the linear model based on molecular connectivity indices.Additionally,the linear model was not suitable for superphilic compounds.By introducing function correction factors to the model,the residual of the prediction model for polar organic compounds was reduced significantly.When the nonlinear estimation was used,the accuracy of the obtained model was further improved.The final prediction model consisted of parameters (0χv)2,(2χv) 1/2, 2χ,3χc, 0χv and 10 correction factors for function groups OH,NH2,NO2,NCOO,etc.The difference between calculated and observed values of logBCF and its causes were analyzed.The robustness of the model was tested by Jackknifed method,based on random grouping and compound classification.
    Uptake of particulate lead via gills of goldfish
    LIU Changfa, TAO Shu, CAO Jun, LI Bengang, Lam Kin Che
    2000, (2):  283-286. 
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    This paper studied the uptake of Pb absorbed on suspended gibbsite via gills of goldfish (Carassius auratus). Under conditions of the concentration of the particulate Pb varied while that of free Pb maintained at a constant level,the levels of both Pb and Al in the gills increased with increasing exposed Pb concentration.The increasing rate (slope 0.171) of Pb level in the blood with the Pb level in the gills was lower than that (slope 0.343) of soluble Pb exposure experiment.Partial Pb adhered on the gills did not transfer into blood.The ratio of Pb/Al in the gills was 1～2 orders of magnitude higher than that in the water,and on the microtome section of filament, the gibbsite particles adhered on gill mucus were observed, indicating the bioavailability of the particulate Pb uptake by the gills of goldfish.The major mechanism was: when the absorbed Pb on suspended particles was flowed into gill filaments,it was desorbed on the surface of gills,and then, passively diffused or transferred by carriers via gill cells into flood,and after the particles stayed on the surface of gill filaments for a short time,in company with sloughed mucus,they were released from the gills along with waterflow.
    Gastric evacuation rate of black sea bream(Sparus macrocephalus)
    ZHANG Bo, SUN Yan, TANG Qisheng
    2000, (2):  287-289. 
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    The gastric evacuation rate of black sea bream(Sparus macrocephalus)weighing 20～40g was determined at 18℃ in laboratory.Three mathematical models were applied to simulate it.The result indicated that all of these three kinds of models fitted to the experiment data,while statistical analysis showed that the linear model was the best,whether the remained food in stomach was expressed by wet weight or dry weight.When the remained food in stomach was expressed by wet weight,the model was Y=1.14-0.06t(r2=0.82,p< 0.001),and by dry weight,it wasY=1.36-0.07t(r2=0 62,p<0.001).The gastric evacuation rate of black sea bream was 6～7% of consumed food per hour at 18℃.
    Comparison analysis on physical and value assessment methods for ecosystems services
    ZHAO Jingzhu, XIAO Han, WU Gang
    2000, (2):  290-292. 
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    Physical assessment method (PAM) and value assessment method (VAM) for ecosystems services assessment were compared, and their strengths and weaknesses were analyzed. The comparison and analysis demonstrated that in some cases,different, even opposite results will be drawn with these two methods for the ecosystems services assessment of one ecosystem. The functions or effects of PAM and VAM are different for different assessment purposes or different spatial scales, but they will promote and complement each other to some extent.
    Genetic variation of geographical provenance of Pinus massoniana-Review and analysis
    LI Dan, PENG Shaolin
    2000, (2):  293-296. 
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    Pinus massoniana is a significant tree species constituting the subtropical forests in China.Based on morphological,physio ecological,chromosome,and molecular levels,the genetic variation of geographical provenance of P.massoniana and its distribution were reviewed,and the methodologies on genetic diversity and the genetic variation patterns of geographical provenance of P.massoniana were synthetically analyzed.The Key problems on molecular ecology of P.massoniana were discussed.
    Vegetation and erosion control: exploration on basic principle of slope engineering
    ZHOU Yue
    2000, (2):  297-300. 
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    During its interaction with local climate and surface and shallow soil,vegetation appears to be of certain hydro mechanical effects,and provides with some engineering properties on erosion control and slope protection.Slope eco engineering integrates these properties with soil for slope protection projects.Along with the increasing awareness of the interactions between vegetation and soil and their significance in erosion control during the past few decades,this biological approach has been widely applied in physical environment improvement and engineered slope protection world wide.Some important contents in slope eco-engineering are the concept of “soil-vegetation system” and the related biological natures and engineering properties.The“soil-vegetation system”concept is a theoretical substance,and its eco biological natures,engineering properties and some internal regulations are the theoretical hypothesis of the substance,which could be the basic materials for setting up the scientific principles of slope eco engineering.
    Hydraulic architecture and drought resistance of woody plants
    LI Jiyue, ZHAI Hongbo
    2000, (2):  301-305. 
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    This paper introduced with emphasis the physiological meaning of hydraulic architecture and its parameters,e.g.,hydraulic conductivity(Kh),specific conductivity(Ks),leaf specific conductivity(LSC),Huber value(Hv) and water storage capacitance(C),the hydraulic architecture patterns of woods and woody plants,and the developmental trend in their research.The relationship between the hydraulic archteciture of woody plants and their drought resistance was tried to be expounded in mechanism.
    Mycorrhizal research on nitrogen-fixing plants
    ZHAO Shuqing, TIAN Chunjie, HE Xingyuan
    2000, (2):  306-310. 
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    Advances in mycorrhizal research on nitrogen-fixing plants were introduced.The universality of mycorrhizal formation in nitrogen fixing plants,the reciprocal promotion effect of symbiosis,and the application prospect of mycorrhizal techniques under stressed conditions were summarized and reviewed.The mechanism of enhancing nitrogen fixation of N fixing plants by mycorrhizal fungi in symbiosis was preliminary discussed.
    Research progress on PGPR/AMF interactions
    LONG Weiwen, WANG Ping, FENG Xinmei, HU Zhengjia, LI Fudi
    2000, (2):  311-314. 
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    As one of the rhizospheric microorganisms PGPR(Plant Growth Promoting Rhizobacteria)and AMF(Arbuscular Mycorrhizal Fungi)play an important role in promoting plant growth.It is of significance to further study and elucidate the interactions between them to utilize and regulate the interactions among rhizospheric microorganisms,and promote and protecte plant growth.Many research results show that on one hand,there exists synergism between PGPR and AMF.AMF can transfer PGPR or act as a media in the process of spread of PGPR along roots,where PGPR create many beneficial conditions for the infection of AMF.Both of them can indirectly enhance the other side's colonization or infection ability through their own promoting role on plant growth.On the other hand,they compete with each other for nutrients and niches,and probably produce some secondary metabolites which cause detrimental effects on the other.However,whether these interactions are synergistic or competitive depends upon the AM fungal or PGPR species involved.So far,the research work is extensive,even in molecular level in some aspects,but not systematic and deep.It is believed however,with the development of techniques in molecular biology and the increasing application of advanced testing methods,the new breakthroughs will be gained in the study and understanding on the interactions.
    Root excretion and plant resistance to metal toxicity
    CHANG Xuexiu, DUAN Changqun, WANG Huanxiao
    2000, (2):  315-320. 
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    Reducing the availability and toxicity of metal pollutants before they enter plant body is one of the main mechanisms of plant resistance to metals.Root system is the first entrance of metal pollutants from soil into plant.It can excrete organic acids,amino acids,sugars,growth substances etc.into rhizosphere.Root excretion affects the metal absorption by plant through changing the physical and chemical characters(such as pH,Eh)of rhizosphere.The metal pollutants are detained outside the roots by chelation,complexation and disposition with root exudates.The quantity and activity of metals in rhizosphere are changed by root exudates through changing the composition,activity and excretion of microbes there.After reviewing the research advances on root excretion and plant resistance to metals,the authors pointed out the existing problems and the major topics and significance of further research.