Table of Content

15 July 2002, Volume 13 Issue 7

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Fractal structure of Abies fabri, dominant tree species in dark coniferous forest at the upper reach of Yangtze River

XIE Chunhua, WEI Jie, GUAN Wenbin, WU Jian'an, LI Chunping, LUO Ji, LI Tongyang

2002, (7):  769-772. 

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Based on the theory of fractal geometry, branching patterns of primitive Abies fabri in the dark coniferous forest ecosystem at the upper reach of Yangtze River were studied. The results showed that the maximum crown width was appeared at inferior 20% of the crown height, and its volume could be simulated by the combination of a round table and a cone. The surface of the crown and their branching patterns of Abies fabri had the common typical fractal characters, the fractal dimensions (FD) were 2.3232 and 1.8119, and the correlation coefficient was 0.99.

Plot analysis in the dark coniferous ecosystem using GPS and GIS techniques

GUAN Wenbin, XIE Chunhua, WU Jian'an, YU Xinxiao, CHEN Gengwei, LI Tongyang

2002, (7):  773-776. 

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It is generally difficult to survey in primary forests located on high altitude region. However, it is convenient to identify and to recognize plots accompanied by GPSand GIStechniques, which can also display the spatial pattern of arbors precisely. Using the method of rapid static positioning cooperated with tape measure, it is concluded that except some points, the positioning was relatively precise, the average value of RMSwas 2.84, variance was 2.96, and △B, △L, and △H were 1.2, 1.2, and 4.3m with their variances being ±0.6, ±1. 1, and ±21.1, respectively, which could meet the needs of forestry management sufficiently. Accompanied by some other models, many ecological processes under small and even medium scale, such as the dynamics of gap succession, could also be simulated visually by GIS. Therefore, the techniques of "2S" were patent for forest ecosystem management under the fine scale, especially in the area of high altitude.

Characteristics and disturbance status of gaps in subalpine fir forest in Southeast Tibet

LUO Daqing, GUO Quanshui, XUE Huiying, Bianbaduoji

2002, (7):  777-780. 

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Characteristics and disturbance status of gaps,including gap size,disturbance frequency, forming patterns of gaps, and quantity of the tree in gap, in subalpine fir forest in Southeast Tibet were studied.The results showed that expanded gaps accounted for 41.73% and canopy gaps accounted for 14.71% of land area in the forest. Averagely, 0.82% and 0.29% of forest area were transformed into expanded and canopy gaps every year. The velocity of gap forming was 0.31 ind·hm^-2·yr^-1. The disturbance cycle of gaps was 345yr. Among16 investigated gaps,there were 78 gap-markers in total, and there were averagely 4.88 trees in each gap. The main reasons of gap forming were gap-markers fallen as well as uprooted and withered,and their external force was strong wind. The possibility of gaps forming reached the maximum while the diameter of arbors was 40～60 cm and the high was 15～20m in the main forest layer. Gaps were formed by many distubances in different age in the subalpine fir forest in Southeast Tibet.

Geostatistical analysis of the pattern of Betula ermanii population in Changbai Mountain

WANG Xiaochun, HAN Shijie, ZOU Chunjing, ZHOU Xiaofeng

2002, (7):  781-784. 

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The distribution pattern and spatial correlation of Betula ermanii population in Changbai Mountain were studied using the theory of geostatistics. According to the data,these mivariograms of Betula ermanii volume were calaculated,the models of semivariograms were simulated, and Kriging interpolation was also done to draw the Kriging map. The results showed that at the elevation of 1650～1700m, the semivariograms of Betula ermanii volume could be described as spherical model,the spatial distribution pattern was the aggregated type,and the population was in a trend of declining.At the elevation of 1750～2000m, the semivariograms of Betula ermanii volume could be described as linear model, the spatial distribution pattern was the random type, the population was stable.At the elevation of 2000～2150m, the semivariograms of Betula ermanii volume could be described as spherical model,the spatial distribution pattern was the aggregated type,and the population was in a tend of increasing. Betula ermanii population in Changbai Moutain was in a trend of moving upper,especially Betula ermanii population in the ecotone.

α diversity of communities and their variety along altitude gradient on northern slope of Changbai Mountain

HAO Zhanqing, YU Deyong, YANG Xiaoming, DING Zhihui

2002, (7):  785-789. 

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From 700 to 2600m on northern slope of Changbai Mountain, twenty plots were investigated with an interval of 100 m in altitude, and α diversity of communities and their variety along altitude gradient were studied. The results showed that in different successional layers of trees, or shrub and herb layers, richness and diversity decreased linearly with the increase of altitude. Tree species decreased from 19 species at 700m to only 1 species at timberline. Shrub and herb species decreased from 20 and 61 species at 700m to 2 and 15 species at 2600m respectively. The peak values of richness of trees and herbs along altitude gradient were appeared just in the ecotones between different types of vegetation, and it reflected the characteristics of high species richness in ecotones

Characteristics of available P in the rhizosphere soil in pure Juglans mandshurica and Larix gmelinii and their mixed plantation

CHEN Yongliang, HAN Shijie, ZHOU Yumei, ZOU Chunjing, ZHANG Junhui

2002, (7):  790-794. 

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The rhizosphere and non rhizosphere soils were sampled in the pure and mixed plantations of Juglans mandshurica and Larix gmelinii by peeling the adhering soil of the roots, and the available Pcontent were analyzed. The results showed that the available Pcontent in the rhizosphere soil in the pure Larix gmelinii was 55.8% higher than that in the non rhizosphere soil, while the available Pcontent in the pure Juglans mandshurica was higher thanthat in the non rhizosphere soil by 10.1%. The roots of Larix gmelinii had important effect on mobilizing Pin the rhizosphere soil. The available Pcontent in rhizosphere soil of Juglans mandshurica in the mixed plantation was higher than that in the pure plantation by 45.2% due to the effects of the roots of Larix gmelinii. The mechanism by which the available Pcontent in the rhizosphere soil of Larix gmelinii was much higher was elucidated by means of Pabsorption, Pdesorption, and inorganic Pgradation.

Community types,phenology and propagation characteristics of Taxus mairei in North Guangdong

LIAO Wenbo, ZHANG Zhiqian, CHEN Zhiming, TANG Changgen, DENG Shifu

2002, (7):  795-801. 

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Community types,phenology and propagation characteristics of Taxus mairei in north Guangdong were studied. The results showed that in north Guangdong province, Taxus mairei mainly distributed in the typical ever green broad leaf forest of lower and mid subtropics dispersedly. Terminal bud of Taxus mairei was formed in late October and begun to grow foliages in mid April,male flower bud was appeared in mid-May and the efflorescence was from late July to late November,female flower bud was formed in late August and the efflorescence was from late October to late January of second year,and the fruit mature period was in early October of second year. Under natural condition,the seed germination needed 2～3 years. Under experimental condition,the germination rate could be up to 82.2%. The effect of cuttage was better by taking mature annual twig and pretreatment by ABT 1 (100 mg·L^-1) from October to November every year,and the rooting rate could be up to 95%.

Influencing mechanism of several shrubs and subshrubs on soil fertility in Keerqin sandy land

SU Yongzhong, ZHAO Halin, ZHANG Tonghui

2002, (7):  802-806. 

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Keerqin sandy land is one of serious desertification areas in the semiarid zone of north China, and shrubs are the dominant plant life form and play an important role in the region. The effects of "fertile island" and rhizosphere of several shrubs and subshrubs were studied. The results showed that the concentrations of organic C, total Nand total P, and values of electrical conductivity (EC) in the soils under the canopy of shrubs increased by 56%, 51%, 37%, and 51%, respectively, compared with those of the soils in open spaces, but there was no significant difference in pHvalue between the soils under shrub canopies and in open spaces. Shrub rhizosphere soils had significant higher contents of organic C, total N, and values of ECas well as lower pHvalue compared to the bulk soils, but there was no significant difference in total Pbetween rhizosphere and bulk soils. There were close relationships between the properties in soils under shrub canopies and the rhizosphere soils, indicating that the development of "fertile island" were favorable to root growth and induced greater amount of rhizodeposition, and vice versa. Soils under Artemisia frigida and Caragada microphylla canopies and rhizospheres had significant higher organic Cand total Ncontents than those of Artemisia halodendron and Salix gordejvii. This results suggested that shrubs were of vital importance for accumulation of nutrients and maintenance of soil fertility in Keerqin sandy land ecosystem.

Effect of enhanced UV-B radiation on polyamine metabolism and endogenous hormone contents in rice (Oryza sativa L.)

LIN Wenxiong, WU Xingchun, LINAG Kangjing, GUO Yuchun, HE Huaqin, CHEN Fangyu, LIANG Yiyuan

2002, (7):  807-813. 

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The results showed that the activities of Agrinine decarboxylase(ADC), Ornithine decarboxylase(ODC) and s Adenosylmethionine decarboxylase(SAMDC) were increased by 165.74%, 104.60% and 89.60% in the leaves of Shan You63(Sy63) and by 59.91%, 41.30% and 23.68% in the leaves of Nancheum(NC). Only ADC and ODC activities were increase by 115.93%, 14.45%, but SAMDC activity was decreased by 33.01% in the leaves of IR_65600-85 respectively in the exposure to enhanced UV-B radiation for 7～14 days. In late treatment time course(21～28d), the activities of ADCand ODCwere increased by 89.72% and 3.71% in the leaves of Sy63 exposed to UV-B radiation for 21～28 days and by 73.95% and 27.38% in the leaves of NC. The activity of ADC was also increased by 94.41%, but ODCactivity was decreased by 13.57% in the leaves of IR_65600-85 compared with the controls. As far as SAMDC was concerned, the enzymic activities in the leaves of Sy63, NCand IR_65600-85 were reduced by 40.06%, 19.20% and 38.21% respectively in the exposure to enhanced UV-B radiation for 21～28 days. The reverse was true in the case of Polyamine Oxidase (PAO), this in turn resulted in increased contents of Polyamine(PA) especially putrescine(Put).In addition, the result also indicated that the contents of IAAand GA_1/3 were significantly reduced in all rice cultivars used for this experiments with enhanced UV-B radiation treatments for 7～28 days, in which the contents of IAAand GA_1/3 were decreased by 58.92% and 45.48% in the leaves of Sy63, by 43.31% and 56.20% in the leaves of NC, and by 38.60% and 47.33% in the leaves of IR_65600-85. The contents of ZRs in the leaves of the three cultivars concerned were lower in earlier treatment time courses (7～14d),but much higher in late courses(21～28d) compared with the their counterparts. With regard to the endogenous hormone of ABA, the content was significantly increased by 144%, 99.6 % and 56.7% respectively in the three rice cultivars concerned exposed to enhanced UV-B radiation for 7～28 days, thereby led to decreased values of IAA/ABA, GA_1/3 /ABA and ZRs/ABA,consequently suppressed growth and development of rice.

Cumulative effect of solar ultraviolet B radiation on pollen germination and tube growth of19 species in vitro

FENG Huyuan, AN Lizhe, TAN Lingling, HOU Zongdong, WANG Xunling

2002, (7):  814-818. 

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In order to determine the response of pollen to UV-B irradiation and the cumulative effects of UV-B exposure time on pollen germination and tube growth of plants,19 species were investigated in vitro by exposing their pollen grains to two levels of enhanced ultravioet B(UV-B_BE)(280～320 nm,350 and 500 mW/m² biologically effective UV-B radiation), simulating8% and 21% stratospheric ozone depletion in Lanzhou, China (36.04°N,1550 m),and to no UV-B (control group).Compared with the control,enhanced UV-B radiation significantly inhibited pollen germination and tube growth in most species.Higher UV-B flux rate caused greater inhibitory effect than lower UV-B radiation level.Several test plants exhibited insensitivity,even stimulation of pollen germination and tube growth to UV-B. The reduction in pollen germination rate and tube growth increased with exposure time, which indicated a cumulative effect of UV-B radiation.It is concluded that changes in pollen susceptibility to UV-B would have a serious ecological consequence under natural conditions.

Effects of decapitation on growth, uptake and distribution of potassium in tobacco

GUO Lizhuo, ZHANG Fusuo, LI Chunjian

2002, (7):  819-822. 

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Compared with intact plants, decapitation did not cause increase in dry weight of tobacco plant and in potassium accumulation8 weeks after the treatment. In intact plants, about 1/3 of assimilation and potassium were transported into the top, and only about 1/3 of those deposited in the leaves. Decapitation resulted in about 1/2 of assimilation and potassium distributing in the leaves, so it was more effective. Application of NAAon the stump of the stem did not influence leaves yields, but accumulation of potassium in the upper and middle leaves was enhanced.

Analysis of formation causes of grassland degradation in Maduo County in the source region of Yellow River

BAI Wanqi, ZHANG Yili, XIE Gaodi, SHEN Zhenxi

2002, (7):  823-826. 

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Natural and artificial factors of grassland degradation in Maduo County in source region of Yellow River were analyzed in this paper. The results showed that overgrazing was the major reason for grassland degradation. Compared with historical average, annual temperature and precipitation in Maduo had an obvious rise since the end of 1980s. Temperature rise concentrated in winter, and precipitation rise concentrated in spring and summer. Therefore, the change in water and heat condition was advantageous to grass growth there. Maduo was a county totally dependent on stock raising, and enlarging livestock population was the only choice for economic development. Together with the pressure of population growth and local Tibetan's traditional value, the number of livestock had been increased continuously, and finally reached summit in the end of 1970s. Since then, the grassland had been kept in the state of overgrazing and degradation, which also created favorable condition for the invasion of pikas, and thus sped up the process of degradation.

Effect of arid climate on underground growth of Bothrichloa ischaemum community

ZHANG Na, LIANG Yimi

2002, (7):  827-832. 

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The underground growth of Bothrichloa ischaemum community in extremely arid year were compared with that of the community in1991 with normal precipitation, and hence, could reflect the effect of drought on underground growth of Bothrichloa ischaemum community. The results indicated that the peak value of underground biomass reached 1249 g穖^-2 in extremely arid year, higher than that in normal year (586 g穖^-2). Most roots distributed downwards in extremely arid year or arid seasons, and distributed upwards in normal year or rain seasons. The turnover rate of underground biomass in extremely arid year was 52.64%, significantly higher than that in normal year (18.36%). In extremely arid year, underground part and aboveground part competed with each other at the middle and later stage of growth, however, in normal year, they increased simultaneously presenting beeline correlativity on the whole. The biomass ratio of underground to aboveground in extremely arid year was 11.19 and significantly higher than that in normal year (2.03). Net underground primary production in extremely arid year was 390.7 g穖^-2 穣r^-1. and 2.63 times higher than that in normal year.

Factors influencing phthogenicity of Colletotrichum gloeosporioides f.sp. veronicae to Veronica persica

ZENG Qing, QIANG Sheng

2002, (7):  833-836. 

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The effects of the characters of the fungus, the growing period of plants and environmental factors on the pathogenicity of Colletotrichum gloeosporioides f.sp. veronicae infecting Veronica persica were studied in pot experiments. The results showed that 1.08×10⁸spores·mL^-1 suspension could kill the seedlings with two cotyledons within one week and cause old plants serious disease. 1×10⁸ spores·mL^-1 was optimal concentration and 1 or 2 weeks old was the best age of the spores for killing birdseye speedwell. The optimal temperature was 15～25℃ for the disease development. More than two days' dew exposure was required to kill the weed. However, the disease was also developed better when corn or soybean flour was added or the darkness period during dew exposure was prolonged.

Correlation between monthly average temperature and grasshopper outbreak in the region around Qinghai Lake based on GIS

ZHANG Hongliang, NI Shaoxiang, DENG Ziwang, CHEN Yun

2002, (7):  837-840. 

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It is necessary to study the relationship between grasshopper and ecological factors for forecasting grasshopper outbreak effectively. Temperature is one of main factors influencing grasshopper outbreak in the region around Qinghai Lake. With the support of Arc/Info and ArcView, monthly average temperatures were simulated under the scale of 150 m by data from sixteen meteorological stations adjacent to Qinghai Lake for adapting the comprehensive method and establishing spatial temperature database. Then, the relationship between grasshopper outbreak and monthly average temperature were analyzed by combining the spatial data of grasshopper density and the spatial data of monthly average temperature. The result showed that effects of monthly average temperature on Grasshopper outbreak were closely related to the life cycle of the dominant grasshopper species in the region, namely, monthly average temperatures of May, June, and July influenced grasshopper outbreak in the current year, and monthly average temperatures of August and September influenced grasshopper outbreak in the next year. Thereby, it could provide a base of establishing forecasting models of grasshopper outbreak.

Biological control efficiency of ladybirds on arthropod pests in cotton agroecosystems

GE Feng, LIU Xianghui, PANG Weidong, DANG Yanqin

2002, (7):  841-844. 

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Based on the systematical investigation of population dynamics of predacious ladybird in different cotton agroecosystem, the energy flow for predacious ladybirds was analyzed by the way of ecological energetic. The biological control efficiency of ladybirds was compared in different planting time and inter crop cotton agroecosystems using available date on the prepapers of ladybird ingestion to pest production. The results showed that the ingestion of predacious ladybirds were 26.45～70kJ·m^-2 yr^-1., accounting for 28.30～47.88% of all predacious natural enemies in different cotton agroecosystems. The biological control efficiency of ladybirds to aphids were 5.07～12.85%, which was decreased in inter crop cotton agroecosystems and the ecosystems with the delay of planting time. It is suggested that the ladybirds play the important role of potential biological control in cotton agroecosystems.

A preliminary study on ingredient of secretion from fungi of orchid mycorrhiza

WU Jingping, QIAN Ji, ZHENG Shizhang

2002, (7):  845-848. 

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Fusarium sp., which was not reported before in orchid mycorrhiza research, was isolated from the roots of Dendrobium desiflorum from Fujian Province by routine work of purification and identification. The results showed that the secretion contained Vitamin B₂, B₆, and folic acid, and mycelia contained Vitamin B₂ and B₆. It was also found that the mycelia of orchid mycorrhizal fungi contained and secreted gibberellin.

A preliminary study on the effect of irrigation on water physiology of Tamarix ramosissima in Cele oasis

ZENG Fanjiang, Andrea Foetzki, LI Xiangyi, ZHANG Ximing, LI Xiaoming, Michael Runge

2002, (7):  849-853. 

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Change characteristics of predawn water potential, water potential daily process, and transpiration rate of Tamarix ramosissima before and after irrigation was studied in Cele oasis in the south fringe of Takelamakan Desert. The results showed that the predawn water potential (-0.93 MPa) after irrigation was higher than that before irrigation (-1.04 MPa), but there was no obvious difference. So, irrigation had certain influences on the recovery of predawn water potential of T. ramosissima. The average value of water potential daily process (-2.29 MPa) after irrigation was lower than that before irrigation (-1.69MPa). Irrigation had no influence on the increase of water potential. The transpiration rate (0.505 mmol穖^-2穝^-1) after irrigation was higher than that before irrigation (0.18mmol穖^-2 穝^-1), and compared to the soil water content and the distribution of root system before and after irrigation, it might be resulted in underground water utilization of T. ramosissima. T. ramosissima could use the underground water with its deep root system. Surface irrigation had no significant effect on the change of water condition of T. ramosissima.

Modeling transfer and partitioning of potentially toxic pollutants in soil crop system for human food security

PAN Genxing, Andrew C.Chang, Albert L.Page

2002, (7):  854-858. 

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Human exposure to potential toxic pollutants and the associated health risk is a focus of current environmental and medical studies. However, the transfer and partitioning of the pollutants in the soil crop systems turns to be a key problem for evaluating the food intake of the pollutants. This paper deals with the methodology and the approach of computer modeling of the soil crop partitioning of the pollutants under agricultural systems for human food security and the elaboration of guidelines for soil protection. Two major models, crop ecological model and soil environmental chemical model, are discussed respectively. These models may be valuable for the research of agricultural environment protection and the development of guidelines for soil protection in China.

Uptake and distribution of Cu,Zn,Pb and Cd in maize related to metals speciation change in rhizosphere

HUANG Yi, CHEN Youjian, TAO Shu

2002, (7):  859-862. 

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The behavior of heavy metals in terrestrial system and the mechanism of VAMplant in toleranting excessive heavy metals in soil were examined with VAMmaize(Zea mays L.).After seven week cultivation in sewage sludging soil,the biomass of VAM (Glomus mosseae) maize was found 1.5 times higher than non mycorrhizal one.Compared with non mycorrhizal maize, the accumulation of Cu,Zn and Pb by mycorrhizal maize was reduced by 10%,18% and 29%, respectively,but the accumulation of Cd was the same.The distribution and speciation change of Cu,Zn,Pb and Cd in rhizosphere of VAMand non mycorrhizal maize were analyzed by using the technique of sequential extraction.Except a significant increase in exchangeable Cu in rhizosphere of VAMmaize, the increased amount of test metals bound to organic matter, carbonates,iron and manganese oxides were significantly higher than those in rhizosphere of non mycorrhizal maize, indicating that the speciation of metals in rhizosphere of mycorrhizal maize growing in contaminated soil tended to be relatively stable. Meanwhile,the influence of metal speciation in rhizosphere on its bioavailability as well as the mechanism of mycorrhizal plant in toleranting excess metals were also discussed.

Characteristics of nitrogen loss from sloping field in red soil area under different cultivation practices

YUAN Donghai, WANG Zhaoqian, CHEN Xin, GUO Xinbo, ZHANG Ruliang

2002, (7):  863-866. 

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The characteristics of nitrogen loss under six types of cultivation practices were studied in Lanxi Water and Soil Conservation Supervision Station of Zhejiang Province. The results showed that compared with the traditional cultivation practice (treatment 5, straight farming), the other cultivation practices including grass strip, contour ditch, contour farming, contour dam, and fallow decreased soil nitrogen loss significantly, and the percentages of nitrogen loss under the 5 types of cultivation practices decreased by 43.46%, 46.55%, 71.36%, 77.05%, and 87.92%, respectively. Soil nitrogen lost mainly with runoff, and it accounted for 81.9～93.4% of total soil nitrogen loss. Dissolved nitrogen was the major form of lost nitrogen and accounted for 78～87.6% of total lost nitrogen in runoff. Nitrogen loss was occurred mainly during May to August, and it accounted for 85～100% of total annual nitrogen loss.

Effect of low molecular weight organic acids on inorganic phosphorus transformation in red soil and its acidity

HU Hongqing, LIAO Lixia, WANG Xinglin

2002, (7):  867-870. 

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Red soil samples collected from southern Hubei province and northern Jiangxi province were tested to analyze their inorganic phosphorus fractions,pHand active aluminum after incubated with added various organic acids.The results indicated that application of organic acids increased the content of Ca₂-P in both red soils,in the order of citric acid>malic acid>succinic acid>acetic acid,did not affect the contens of Ca₈-P and Ca₁₀-P,but usually reduced Fe P,Al Pand O P.The pHvalues of the soils treated by organic acids,except for acetic acid,were reduced by 0.65～1.96,compared with the control.Soil active Al extracted with 0.02 mol·L^-1 CaCl₂ in treatments with citric,malic and succinic acid was 5.7～51.3 tmes as the control,and Al extracted with 1 mol·L^-1 KCl also increased 4.0～67.3 times.However,acetic acid had little influence on active soil Al.It was concluded that in red soils, organic acid could improve phosphorus availability,but enhance the soil toxicity caused by active Al

Effect of suspended silt from dredging at Yangtze estuary on Brachionus plicatilis

WANG Jinqiu, XU Zhaoli, SHI Chun, CHEN Yaqu

2002, (7):  871-874. 

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The effect of suspended silt from dredging at Yangtze estuary on Brachionus plicatilis was investigated by clonal culture (to construct life table) and population accumulative culture. The intrinsic increasing rate of the rotifer population was greatly reduced under different concentrations (1, 3, 5, 7 and 9mg穖L^-1) of silt, from 29.6% to 64.1%, and to a maximum of 130.0%. The suspended silt affected population survival rate, rather than its reproduction rate. In accumulative culture, the densities of female, males, parthenogenetic eggs, and resting eggs in the population were not affected by silt. It was concluded that the presence of suspended silt should have a certain negative influence on the rotifer population in dredging Yangtze estuary.

Effects of food concentration on population growth, body size, and egg size of the freshwater rotifer Brachionus angularis

HU Haoyuan, XI Yilong, GENG Hong

2002, (7):  875-878. 

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With the food Chlorella pyrenoidosa and the method of population accumulative culture, the effects of food concentration on the population growth, body size, and egg size of the freshwater rotifer Brachionus angularis were studied. The results showed that there were very significant effects of food concentrations on the population growth rate, body size and egg size. The relationship between the population growth rate and the food concentration was curvilinear correlation. When the food concentration was 8.2453?10⁶cells穖L^-1, the population growth rate reached it's maximum, 0.6085d-1. Body size tended to enlarge with increasing food concentration. At the intermediate range of food levels between 6.0?10⁶ cells穖L^-1 and 9.0?10⁶ cells穖L^-1, the egg volume was larger than those at the other food concentrations.

Fractal structure of Abies fabri, dominant tree species in dark coniferous forest at the upper reach of Yangtze River

XIE Chunhua, WEI Jie, GUAN Wenbin, WU Jian'an, LI Chunping, LUO Ji, LI Tongyang

2002, (7):  769-772. 

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Based on the theory of fractal geometry, branching patterns of primitive Abies fabri in the dark coniferous forest ecosystem at the upper reach of Yangtze River were studied. The results showed that the maximum crown width was appeared at inferior 20% of the crown height, and its volume could be simulated by the combination of a round table and a cone. The surface of the crown and their branching patterns of Abies fabri had the common typical fractal characters, the fractal dimensions (FD) were 2.3232 and 1.8119, and the correlation coefficient was 0.99.

Plot analysis in the dark coniferous ecosystem using GPS and GIS techniques

GUAN Wenbin, XIE Chunhua, WU Jian'an, YU Xinxiao, CHEN Gengwei, LI Tongyang

2002, (7):  773-776. 

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It is generally difficult to survey in primary forests located on high altitude region. However, it is convenient to identify and to recognize plots accompanied by GPSand GIStechniques, which can also display the spatial pattern of arbors precisely. Using the method of rapid static positioning cooperated with tape measure, it is concluded that except some points, the positioning was relatively precise, the average value of RMSwas 2.84, variance was 2.96, and △B, △L, and △H were 1.2, 1.2, and 4.3m with their variances being ±0.6, ±1. 1, and ±21.1, respectively, which could meet the needs of forestry management sufficiently. Accompanied by some other models, many ecological processes under small and even medium scale, such as the dynamics of gap succession, could also be simulated visually by GIS. Therefore, the techniques of "2S" were patent for forest ecosystem management under the fine scale, especially in the area of high altitude.

Characteristics and disturbance status of gaps in subalpine fir forest in Southeast Tibet

LUO Daqing, GUO Quanshui, XUE Huiying, Bianbaduoji

2002, (7):  777-780. 

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Characteristics and disturbance status of gaps,including gap size,disturbance frequency, forming patterns of gaps, and quantity of the tree in gap, in subalpine fir forest in Southeast Tibet were studied.The results showed that expanded gaps accounted for 41.73% and canopy gaps accounted for 14.71% of land area in the forest. Averagely, 0.82% and 0.29% of forest area were transformed into expanded and canopy gaps every year. The velocity of gap forming was 0.31 ind·hm^-2·yr^-1. The disturbance cycle of gaps was 345yr. Among16 investigated gaps,there were 78 gap-markers in total, and there were averagely 4.88 trees in each gap. The main reasons of gap forming were gap-markers fallen as well as uprooted and withered,and their external force was strong wind. The possibility of gaps forming reached the maximum while the diameter of arbors was 40～60 cm and the high was 15～20m in the main forest layer. Gaps were formed by many distubances in different age in the subalpine fir forest in Southeast Tibet.

Geostatistical analysis of the pattern of Betula ermanii population in Changbai Mountain

WANG Xiaochun, HAN Shijie, ZOU Chunjing, ZHOU Xiaofeng

2002, (7):  781-784. 

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The distribution pattern and spatial correlation of Betula ermanii population in Changbai Mountain were studied using the theory of geostatistics. According to the data,these mivariograms of Betula ermanii volume were calaculated,the models of semivariograms were simulated, and Kriging interpolation was also done to draw the Kriging map. The results showed that at the elevation of 1650～1700m, the semivariograms of Betula ermanii volume could be described as spherical model,the spatial distribution pattern was the aggregated type,and the population was in a trend of declining.At the elevation of 1750～2000m, the semivariograms of Betula ermanii volume could be described as linear model, the spatial distribution pattern was the random type, the population was stable.At the elevation of 2000～2150m, the semivariograms of Betula ermanii volume could be described as spherical model,the spatial distribution pattern was the aggregated type,and the population was in a tend of increasing. Betula ermanii population in Changbai Moutain was in a trend of moving upper,especially Betula ermanii population in the ecotone.

α diversity of communities and their variety along altitude gradient on northern slope of Changbai Mountain

HAO Zhanqing, YU Deyong, YANG Xiaoming, DING Zhihui

2002, (7):  785-789. 

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From 700 to 2600m on northern slope of Changbai Mountain, twenty plots were investigated with an interval of 100 m in altitude, and α diversity of communities and their variety along altitude gradient were studied. The results showed that in different successional layers of trees, or shrub and herb layers, richness and diversity decreased linearly with the increase of altitude. Tree species decreased from 19 species at 700m to only 1 species at timberline. Shrub and herb species decreased from 20 and 61 species at 700m to 2 and 15 species at 2600m respectively. The peak values of richness of trees and herbs along altitude gradient were appeared just in the ecotones between different types of vegetation, and it reflected the characteristics of high species richness in ecotones

Characteristics of available P in the rhizosphere soil in pure Juglans mandshurica and Larix gmelinii and their mixed plantation

CHEN Yongliang, HAN Shijie, ZHOU Yumei, ZOU Chunjing, ZHANG Junhui

2002, (7):  790-794. 

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The rhizosphere and non rhizosphere soils were sampled in the pure and mixed plantations of Juglans mandshurica and Larix gmelinii by peeling the adhering soil of the roots, and the available Pcontent were analyzed. The results showed that the available Pcontent in the rhizosphere soil in the pure Larix gmelinii was 55.8% higher than that in the non rhizosphere soil, while the available Pcontent in the pure Juglans mandshurica was higher thanthat in the non rhizosphere soil by 10.1%. The roots of Larix gmelinii had important effect on mobilizing Pin the rhizosphere soil. The available Pcontent in rhizosphere soil of Juglans mandshurica in the mixed plantation was higher than that in the pure plantation by 45.2% due to the effects of the roots of Larix gmelinii. The mechanism by which the available Pcontent in the rhizosphere soil of Larix gmelinii was much higher was elucidated by means of Pabsorption, Pdesorption, and inorganic Pgradation.

Community types,phenology and propagation characteristics of Taxus mairei in North Guangdong

LIAO Wenbo, ZHANG Zhiqian, CHEN Zhiming, TANG Changgen, DENG Shifu

2002, (7):  795-801. 

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Community types,phenology and propagation characteristics of Taxus mairei in north Guangdong were studied. The results showed that in north Guangdong province, Taxus mairei mainly distributed in the typical ever green broad leaf forest of lower and mid subtropics dispersedly. Terminal bud of Taxus mairei was formed in late October and begun to grow foliages in mid April,male flower bud was appeared in mid-May and the efflorescence was from late July to late November,female flower bud was formed in late August and the efflorescence was from late October to late January of second year,and the fruit mature period was in early October of second year. Under natural condition,the seed germination needed 2～3 years. Under experimental condition,the germination rate could be up to 82.2%. The effect of cuttage was better by taking mature annual twig and pretreatment by ABT 1 (100 mg·L^-1) from October to November every year,and the rooting rate could be up to 95%.

Influencing mechanism of several shrubs and subshrubs on soil fertility in Keerqin sandy land

SU Yongzhong, ZHAO Halin, ZHANG Tonghui

2002, (7):  802-806. 

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Keerqin sandy land is one of serious desertification areas in the semiarid zone of north China, and shrubs are the dominant plant life form and play an important role in the region. The effects of "fertile island" and rhizosphere of several shrubs and subshrubs were studied. The results showed that the concentrations of organic C, total Nand total P, and values of electrical conductivity (EC) in the soils under the canopy of shrubs increased by 56%, 51%, 37%, and 51%, respectively, compared with those of the soils in open spaces, but there was no significant difference in pHvalue between the soils under shrub canopies and in open spaces. Shrub rhizosphere soils had significant higher contents of organic C, total N, and values of ECas well as lower pHvalue compared to the bulk soils, but there was no significant difference in total Pbetween rhizosphere and bulk soils. There were close relationships between the properties in soils under shrub canopies and the rhizosphere soils, indicating that the development of "fertile island" were favorable to root growth and induced greater amount of rhizodeposition, and vice versa. Soils under Artemisia frigida and Caragada microphylla canopies and rhizospheres had significant higher organic Cand total Ncontents than those of Artemisia halodendron and Salix gordejvii. This results suggested that shrubs were of vital importance for accumulation of nutrients and maintenance of soil fertility in Keerqin sandy land ecosystem.

Effect of enhanced UV-B radiation on polyamine metabolism and endogenous hormone contents in rice (Oryza sativa L.)

LIN Wenxiong, WU Xingchun, LINAG Kangjing, GUO Yuchun, HE Huaqin, CHEN Fangyu, LIANG Yiyuan

2002, (7):  807-813. 

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The results showed that the activities of Agrinine decarboxylase(ADC), Ornithine decarboxylase(ODC) and s Adenosylmethionine decarboxylase(SAMDC) were increased by 165.74%, 104.60% and 89.60% in the leaves of Shan You63(Sy63) and by 59.91%, 41.30% and 23.68% in the leaves of Nancheum(NC). Only ADC and ODC activities were increase by 115.93%, 14.45%, but SAMDC activity was decreased by 33.01% in the leaves of IR_65600-85 respectively in the exposure to enhanced UV-B radiation for 7～14 days. In late treatment time course(21～28d), the activities of ADCand ODCwere increased by 89.72% and 3.71% in the leaves of Sy63 exposed to UV-B radiation for 21～28 days and by 73.95% and 27.38% in the leaves of NC. The activity of ADC was also increased by 94.41%, but ODCactivity was decreased by 13.57% in the leaves of IR_65600-85 compared with the controls. As far as SAMDC was concerned, the enzymic activities in the leaves of Sy63, NCand IR_65600-85 were reduced by 40.06%, 19.20% and 38.21% respectively in the exposure to enhanced UV-B radiation for 21～28 days. The reverse was true in the case of Polyamine Oxidase (PAO), this in turn resulted in increased contents of Polyamine(PA) especially putrescine(Put).In addition, the result also indicated that the contents of IAAand GA_1/3 were significantly reduced in all rice cultivars used for this experiments with enhanced UV-B radiation treatments for 7～28 days, in which the contents of IAAand GA_1/3 were decreased by 58.92% and 45.48% in the leaves of Sy63, by 43.31% and 56.20% in the leaves of NC, and by 38.60% and 47.33% in the leaves of IR_65600-85. The contents of ZRs in the leaves of the three cultivars concerned were lower in earlier treatment time courses (7～14d),but much higher in late courses(21～28d) compared with the their counterparts. With regard to the endogenous hormone of ABA, the content was significantly increased by 144%, 99.6 % and 56.7% respectively in the three rice cultivars concerned exposed to enhanced UV-B radiation for 7～28 days, thereby led to decreased values of IAA/ABA, GA_1/3 /ABA and ZRs/ABA,consequently suppressed growth and development of rice.

Cumulative effect of solar ultraviolet B radiation on pollen germination and tube growth of19 species in vitro

FENG Huyuan, AN Lizhe, TAN Lingling, HOU Zongdong, WANG Xunling

2002, (7):  814-818. 

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In order to determine the response of pollen to UV-B irradiation and the cumulative effects of UV-B exposure time on pollen germination and tube growth of plants,19 species were investigated in vitro by exposing their pollen grains to two levels of enhanced ultravioet B(UV-B_BE)(280～320 nm,350 and 500 mW/m² biologically effective UV-B radiation), simulating8% and 21% stratospheric ozone depletion in Lanzhou, China (36.04°N,1550 m),and to no UV-B (control group).Compared with the control,enhanced UV-B radiation significantly inhibited pollen germination and tube growth in most species.Higher UV-B flux rate caused greater inhibitory effect than lower UV-B radiation level.Several test plants exhibited insensitivity,even stimulation of pollen germination and tube growth to UV-B. The reduction in pollen germination rate and tube growth increased with exposure time, which indicated a cumulative effect of UV-B radiation.It is concluded that changes in pollen susceptibility to UV-B would have a serious ecological consequence under natural conditions.

Effects of decapitation on growth, uptake and distribution of potassium in tobacco

GUO Lizhuo, ZHANG Fusuo, LI Chunjian

2002, (7):  819-822. 

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Compared with intact plants, decapitation did not cause increase in dry weight of tobacco plant and in potassium accumulation8 weeks after the treatment. In intact plants, about 1/3 of assimilation and potassium were transported into the top, and only about 1/3 of those deposited in the leaves. Decapitation resulted in about 1/2 of assimilation and potassium distributing in the leaves, so it was more effective. Application of NAAon the stump of the stem did not influence leaves yields, but accumulation of potassium in the upper and middle leaves was enhanced.

Analysis of formation causes of grassland degradation in Maduo County in the source region of Yellow River

BAI Wanqi, ZHANG Yili, XIE Gaodi, SHEN Zhenxi

2002, (7):  823-826. 

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Natural and artificial factors of grassland degradation in Maduo County in source region of Yellow River were analyzed in this paper. The results showed that overgrazing was the major reason for grassland degradation. Compared with historical average, annual temperature and precipitation in Maduo had an obvious rise since the end of 1980s. Temperature rise concentrated in winter, and precipitation rise concentrated in spring and summer. Therefore, the change in water and heat condition was advantageous to grass growth there. Maduo was a county totally dependent on stock raising, and enlarging livestock population was the only choice for economic development. Together with the pressure of population growth and local Tibetan's traditional value, the number of livestock had been increased continuously, and finally reached summit in the end of 1970s. Since then, the grassland had been kept in the state of overgrazing and degradation, which also created favorable condition for the invasion of pikas, and thus sped up the process of degradation.

Effect of arid climate on underground growth of Bothrichloa ischaemum community

ZHANG Na, LIANG Yimi

2002, (7):  827-832. 

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The underground growth of Bothrichloa ischaemum community in extremely arid year were compared with that of the community in1991 with normal precipitation, and hence, could reflect the effect of drought on underground growth of Bothrichloa ischaemum community. The results indicated that the peak value of underground biomass reached 1249 g穖^-2 in extremely arid year, higher than that in normal year (586 g穖^-2). Most roots distributed downwards in extremely arid year or arid seasons, and distributed upwards in normal year or rain seasons. The turnover rate of underground biomass in extremely arid year was 52.64%, significantly higher than that in normal year (18.36%). In extremely arid year, underground part and aboveground part competed with each other at the middle and later stage of growth, however, in normal year, they increased simultaneously presenting beeline correlativity on the whole. The biomass ratio of underground to aboveground in extremely arid year was 11.19 and significantly higher than that in normal year (2.03). Net underground primary production in extremely arid year was 390.7 g穖^-2 穣r^-1. and 2.63 times higher than that in normal year.

Factors influencing phthogenicity of Colletotrichum gloeosporioides f.sp. veronicae to Veronica persica

ZENG Qing, QIANG Sheng

2002, (7):  833-836. 

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The effects of the characters of the fungus, the growing period of plants and environmental factors on the pathogenicity of Colletotrichum gloeosporioides f.sp. veronicae infecting Veronica persica were studied in pot experiments. The results showed that 1.08×10⁸spores·mL^-1 suspension could kill the seedlings with two cotyledons within one week and cause old plants serious disease. 1×10⁸ spores·mL^-1 was optimal concentration and 1 or 2 weeks old was the best age of the spores for killing birdseye speedwell. The optimal temperature was 15～25℃ for the disease development. More than two days' dew exposure was required to kill the weed. However, the disease was also developed better when corn or soybean flour was added or the darkness period during dew exposure was prolonged.

Correlation between monthly average temperature and grasshopper outbreak in the region around Qinghai Lake based on GIS

ZHANG Hongliang, NI Shaoxiang, DENG Ziwang, CHEN Yun

2002, (7):  837-840. 

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It is necessary to study the relationship between grasshopper and ecological factors for forecasting grasshopper outbreak effectively. Temperature is one of main factors influencing grasshopper outbreak in the region around Qinghai Lake. With the support of Arc/Info and ArcView, monthly average temperatures were simulated under the scale of 150 m by data from sixteen meteorological stations adjacent to Qinghai Lake for adapting the comprehensive method and establishing spatial temperature database. Then, the relationship between grasshopper outbreak and monthly average temperature were analyzed by combining the spatial data of grasshopper density and the spatial data of monthly average temperature. The result showed that effects of monthly average temperature on Grasshopper outbreak were closely related to the life cycle of the dominant grasshopper species in the region, namely, monthly average temperatures of May, June, and July influenced grasshopper outbreak in the current year, and monthly average temperatures of August and September influenced grasshopper outbreak in the next year. Thereby, it could provide a base of establishing forecasting models of grasshopper outbreak.

Biological control efficiency of ladybirds on arthropod pests in cotton agroecosystems

GE Feng, LIU Xianghui, PANG Weidong, DANG Yanqin

2002, (7):  841-844. 

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Based on the systematical investigation of population dynamics of predacious ladybird in different cotton agroecosystem, the energy flow for predacious ladybirds was analyzed by the way of ecological energetic. The biological control efficiency of ladybirds was compared in different planting time and inter crop cotton agroecosystems using available date on the prepapers of ladybird ingestion to pest production. The results showed that the ingestion of predacious ladybirds were 26.45～70kJ·m^-2 yr^-1., accounting for 28.30～47.88% of all predacious natural enemies in different cotton agroecosystems. The biological control efficiency of ladybirds to aphids were 5.07～12.85%, which was decreased in inter crop cotton agroecosystems and the ecosystems with the delay of planting time. It is suggested that the ladybirds play the important role of potential biological control in cotton agroecosystems.

A preliminary study on ingredient of secretion from fungi of orchid mycorrhiza

WU Jingping, QIAN Ji, ZHENG Shizhang

2002, (7):  845-848. 

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Fusarium sp., which was not reported before in orchid mycorrhiza research, was isolated from the roots of Dendrobium desiflorum from Fujian Province by routine work of purification and identification. The results showed that the secretion contained Vitamin B₂, B₆, and folic acid, and mycelia contained Vitamin B₂ and B₆. It was also found that the mycelia of orchid mycorrhizal fungi contained and secreted gibberellin.

A preliminary study on the effect of irrigation on water physiology of Tamarix ramosissima in Cele oasis

ZENG Fanjiang, Andrea Foetzki, LI Xiangyi, ZHANG Ximing, LI Xiaoming, Michael Runge

2002, (7):  849-853. 

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Change characteristics of predawn water potential, water potential daily process, and transpiration rate of Tamarix ramosissima before and after irrigation was studied in Cele oasis in the south fringe of Takelamakan Desert. The results showed that the predawn water potential (-0.93 MPa) after irrigation was higher than that before irrigation (-1.04 MPa), but there was no obvious difference. So, irrigation had certain influences on the recovery of predawn water potential of T. ramosissima. The average value of water potential daily process (-2.29 MPa) after irrigation was lower than that before irrigation (-1.69MPa). Irrigation had no influence on the increase of water potential. The transpiration rate (0.505 mmol穖^-2穝^-1) after irrigation was higher than that before irrigation (0.18mmol穖^-2 穝^-1), and compared to the soil water content and the distribution of root system before and after irrigation, it might be resulted in underground water utilization of T. ramosissima. T. ramosissima could use the underground water with its deep root system. Surface irrigation had no significant effect on the change of water condition of T. ramosissima.

Modeling transfer and partitioning of potentially toxic pollutants in soil crop system for human food security

PAN Genxing, Andrew C.Chang, Albert L.Page

2002, (7):  854-858. 

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Human exposure to potential toxic pollutants and the associated health risk is a focus of current environmental and medical studies. However, the transfer and partitioning of the pollutants in the soil crop systems turns to be a key problem for evaluating the food intake of the pollutants. This paper deals with the methodology and the approach of computer modeling of the soil crop partitioning of the pollutants under agricultural systems for human food security and the elaboration of guidelines for soil protection. Two major models, crop ecological model and soil environmental chemical model, are discussed respectively. These models may be valuable for the research of agricultural environment protection and the development of guidelines for soil protection in China.

Uptake and distribution of Cu,Zn,Pb and Cd in maize related to metals speciation change in rhizosphere

HUANG Yi, CHEN Youjian, TAO Shu

2002, (7):  859-862. 

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The behavior of heavy metals in terrestrial system and the mechanism of VAMplant in toleranting excessive heavy metals in soil were examined with VAMmaize(Zea mays L.).After seven week cultivation in sewage sludging soil,the biomass of VAM (Glomus mosseae) maize was found 1.5 times higher than non mycorrhizal one.Compared with non mycorrhizal maize, the accumulation of Cu,Zn and Pb by mycorrhizal maize was reduced by 10%,18% and 29%, respectively,but the accumulation of Cd was the same.The distribution and speciation change of Cu,Zn,Pb and Cd in rhizosphere of VAMand non mycorrhizal maize were analyzed by using the technique of sequential extraction.Except a significant increase in exchangeable Cu in rhizosphere of VAMmaize, the increased amount of test metals bound to organic matter, carbonates,iron and manganese oxides were significantly higher than those in rhizosphere of non mycorrhizal maize, indicating that the speciation of metals in rhizosphere of mycorrhizal maize growing in contaminated soil tended to be relatively stable. Meanwhile,the influence of metal speciation in rhizosphere on its bioavailability as well as the mechanism of mycorrhizal plant in toleranting excess metals were also discussed.

Characteristics of nitrogen loss from sloping field in red soil area under different cultivation practices

YUAN Donghai, WANG Zhaoqian, CHEN Xin, GUO Xinbo, ZHANG Ruliang

2002, (7):  863-866. 

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The characteristics of nitrogen loss under six types of cultivation practices were studied in Lanxi Water and Soil Conservation Supervision Station of Zhejiang Province. The results showed that compared with the traditional cultivation practice (treatment 5, straight farming), the other cultivation practices including grass strip, contour ditch, contour farming, contour dam, and fallow decreased soil nitrogen loss significantly, and the percentages of nitrogen loss under the 5 types of cultivation practices decreased by 43.46%, 46.55%, 71.36%, 77.05%, and 87.92%, respectively. Soil nitrogen lost mainly with runoff, and it accounted for 81.9～93.4% of total soil nitrogen loss. Dissolved nitrogen was the major form of lost nitrogen and accounted for 78～87.6% of total lost nitrogen in runoff. Nitrogen loss was occurred mainly during May to August, and it accounted for 85～100% of total annual nitrogen loss.

Effect of low molecular weight organic acids on inorganic phosphorus transformation in red soil and its acidity

HU Hongqing, LIAO Lixia, WANG Xinglin

2002, (7):  867-870. 

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Red soil samples collected from southern Hubei province and northern Jiangxi province were tested to analyze their inorganic phosphorus fractions,pHand active aluminum after incubated with added various organic acids.The results indicated that application of organic acids increased the content of Ca₂-P in both red soils,in the order of citric acid>malic acid>succinic acid>acetic acid,did not affect the contens of Ca₈-P and Ca₁₀-P,but usually reduced Fe P,Al Pand O P.The pHvalues of the soils treated by organic acids,except for acetic acid,were reduced by 0.65～1.96,compared with the control.Soil active Al extracted with 0.02 mol·L^-1 CaCl₂ in treatments with citric,malic and succinic acid was 5.7～51.3 tmes as the control,and Al extracted with 1 mol·L^-1 KCl also increased 4.0～67.3 times.However,acetic acid had little influence on active soil Al.It was concluded that in red soils, organic acid could improve phosphorus availability,but enhance the soil toxicity caused by active Al

Effect of suspended silt from dredging at Yangtze estuary on Brachionus plicatilis

WANG Jinqiu, XU Zhaoli, SHI Chun, CHEN Yaqu

2002, (7):  871-874. 

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The effect of suspended silt from dredging at Yangtze estuary on Brachionus plicatilis was investigated by clonal culture (to construct life table) and population accumulative culture. The intrinsic increasing rate of the rotifer population was greatly reduced under different concentrations (1, 3, 5, 7 and 9mg穖L^-1) of silt, from 29.6% to 64.1%, and to a maximum of 130.0%. The suspended silt affected population survival rate, rather than its reproduction rate. In accumulative culture, the densities of female, males, parthenogenetic eggs, and resting eggs in the population were not affected by silt. It was concluded that the presence of suspended silt should have a certain negative influence on the rotifer population in dredging Yangtze estuary.

Effects of food concentration on population growth, body size, and egg size of the freshwater rotifer Brachionus angularis

HU Haoyuan, XI Yilong, GENG Hong

2002, (7):  875-878. 

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With the food Chlorella pyrenoidosa and the method of population accumulative culture, the effects of food concentration on the population growth, body size, and egg size of the freshwater rotifer Brachionus angularis were studied. The results showed that there were very significant effects of food concentrations on the population growth rate, body size and egg size. The relationship between the population growth rate and the food concentration was curvilinear correlation. When the food concentration was 8.2453?10⁶cells穖L^-1, the population growth rate reached it's maximum, 0.6085d-1. Body size tended to enlarge with increasing food concentration. At the intermediate range of food levels between 6.0?10⁶ cells穖L^-1 and 9.0?10⁶ cells穖L^-1, the egg volume was larger than those at the other food concentrations.

International trends of applied ecology and its future development in China

ZHOU Qixing, SUN Shunjiang

2002, (7):  879-884. 

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Internationally applied ecology was born around 25～40 years ago in order to adapt and serve the needs of mitigating increasingly environmental pollution and ecological destroy in developed western countries at that time. All the times applied ecological principles thus underpin most efforts at solving increasingly deterioration of natural resources and serious eco environmental problems as its keystone and researching kernel with the development of the subject. At the advent of the 21st century, human beings enter into the age of applied ecology. There are five international features of applied ecology, including more attention to many sided applications, special emphasis on the intersection with engineering, strongly keeping on mutual links with basic ecology, omnidirectional adoption of new methods and new technology, and side by side trends of microcosmic mechanisms and macroscopical regulation. Although we must connect with international applied ecology and absorb distillates from the subject in developed western countries, development of applied ecology in China in the future, in particular, at the beginnings of the 21st century should not deviate from aiming at the solution of increasingly environmental pollution and ecological destroy that is one of the most important basic situations of the country.

Important ecological topics on regional scale ecosystem management in China

YU Guirui, XIE Gaodi, YU Zhenliang, WANG Qiufeng

2002, (7):  885-891. 

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Ecosystem management is a synthetic applied ecology concerning ecosystem management theories, practical technologies, relevant policies and management strategies. It is not only an urgent need for the sustainable development of human society, but also an important tendency and scientific task of ecosystem management to develop integrated studies on models of global or regional scale ecosystem management and the relevant scientific problems. For this reason, we systematically expounded a series of important ecological topics, such as the synthetic evaluation and ecological mechanism of the services, sustainability, complexity, and indeterminacy of ecosystem, the ecological basis of natural resources conservation, ecosystem health, and the rehabilitation of degraded ecosystem, basic ecological processes for ecosystem management, theories and practice on adaptive management of ecosystem, ecosystem network study, monitor, and achievement integration, as well as synthetic special topic studies on regional scale ecosystem management etc. Research advances and tendencies of these topics at home and abroad were also reviewed.

On eco-ethics and sustainable development of natural resources

WANG Qingli, DENG Hongbing

2002, (7):  892-894. 

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In this paper, definition of natural resources was discussed at first, and chief characteristics of natural resources were concluded and summarized systematically. Then, in point of eco-ethics, relationship between natural resources and human was discussed. Human in the contemporary era should hold the responsibilities and commitments to remain abundant resources for survival and development of the offspring, and it is the same important to meet the requirement of human in the contemporary era and the offspring. Bringing eco-ethics into the practice of protection, exploitation, and sustainable development of natural resources has very important theoretic and practical significance undoubtedly. Therefore, approaches and main measures to sustainable development of natural resources were also discussed in this paper.

Response of bryophytes to global change and its bioindicatortation

WU Yuhuan, GAO Chien, CHENG Guodong, YU Xinghua, CAO Tong

2002, (7):  895-900. 

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Bryophytes are sensitive to atmosphere components concentration and global climate change resulted from relatively simple structures. Bryophyte is an ideal kind of biological indicator of global changes, environmental pollution, nutrient condition, forest integrity and ecosystem health. In order to use bryophytes as indicators to environmental and global changes, further studies on response and adaptation of bryophytes to the global changes are needed.

Bio-active substances derived from marine microorganisms

LIU Quanyong, HU Jiangchun, XUE Delin, MA Chengxin, WANG Shujin

2002, (7):  901-905. 

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Marine microorganisms,which are taxonomically diverse and genetically special,have powerful potential in producing novel bio-active substances.This article summarized research progress in this respect.The results showed that marine bacteria which are main marine microorganism flora can produce rich kinds of bio-active substances and that even though marine actinomycetes and marine fungi are not as many as marine bacteria in species and quantity,they should be paid no less attention about their bio-active substances.Besides,present research are limited to those marine microorganisms which are easily cultured.One of the future research trends will be focused on bio-active substances derived from non culturable marine microorganisms.

Cu hyperaccumulators in mining area

JIANG Liying, SHI Weiyong, YANG Xiaoe, FU Chengxin, CHEN Weiguang

2002, (7):  906-908. 

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Plant species distributing in three Cu mining area were investigated, and Cu concentrations in soils and plants were analyzed. The results showed that Cu ore deposit mostly was distributed at the altitude of about 630 m. Elsholtzia splendens and Rumex acetosa were distributed only on the Cu ore deposit or the place with high Cu concentration, and the maximum Cu concentrations in these two plants were 1060 mg穔g-1 DWand 1006 mg穔g-1 DW, which reached the critical of hyperaccumulator. Cu accumulations in Elsholtzia splendens and Rumex acetosa were positively and closely correlated with Cu concentration in soil.

Correlation between desertification and variations of soil and surface vegetation in agriculture pasture ecotone -A case study in Kangbao county, Northern Hebei Province

SHENG Xuebin, LIU Yunxia, SUN Jianzhong

2002, (7):  909-910. 

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In the agriculture pasture ecotone, due to its specific natural condition, the natural system is unstable, the self regulation capability is weak, the equilibrium is easily broken, and hence the habitat is fairly vulnerable. During last 20 years, the increasing population and livestock, over-reclamation, over-grazing, over-deforesting, and other intensified negative human activities in this area resulted in surface soil coarsening, organic matter content in soil decreasing, vegetation coverage decreasing, community structure varying and degrading, and hence desertification of the land was aggravated. The results also proved that there was close correlation between desertification and the variations of soil and surface vegetation.

Synthetic evaluation on stand quality of protection forests in the Three Gorges Reservoir Region in Western Hubei Province

LIU Xuequan, TANG Wanpeng, TANG Jingming, ZHANG Jialai

2002, (7):  911-914. 

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Stand qualities of 19 kinds of protection forests in the Three Gorges Reservoir Region in Western Hubei Province were evaluated synthetically by using12 indexes,and could be classified into four different grades. The relationships between stand quality and some major factors such as crown density,elevation,and origin were also discussed in this paper. The results showed that elevation was a very important factor that influenced the stand quality,and the stand quality of natrural forest was higher than other forests. Moreover,some strategies on protection forest construction and stand quality optimization were put forward.