Table of Content

15 September 2003, Volume 14 Issue 9

Previous Issue    Next Issue

Regeneration in gaps of the middle-mountain moist evergreen broad-leaved forest of Ailao Mountains

HE Yongtao, LI Guicai, CAO Min, TANG Yong

2003, (9):  1399-1404. 

Asbtract ( 0 )  

On the basis of investigation on gaps in the middle-mountain moist evergreen broad-leaved forest of Ailao Mountains Natural Reserve, Yunnan Province, tree seedlings (H<50 cm) composition were compared in the gaps and the non-gap stand.The results showed that the dominant tree species of the forest were not preponderated over others in the gaps.The composition of tree seedlings in the gaps differed from those in the non-gap stand.The species diversity of tree seedlings in the gaps(H= 2.73, D = 0.89)were higher than those in the non-gap stand (H = 2.25, D=0.82), and the Jaccard correlative coefficient were only 0.6.The density of tree seedlings in the gaps (38636 N·hm^-2) was much higher than that in the non-gap stand (17323 N·hm^-2), of which many species were only found in the gaps.The dominant height of the tree seedling in the gaps and the non-gap stand were also 11～20 cm, but the percentage of the tree seedlings higher than 20cm in the gaps was significantly higher than that in the non-gap stand.The gap sizes had important impact on the tree seedling germination, and different species of tree seedling dominated in different size classes of gap.

Flora analysis of riparian plant communities on the northern slope of Changbai Mountain

DENG Hongbing, WANG Qingchun, DAI Limin, WANG Qingli, WANG Shaoxian

2003, (9):  1405-1410. 

Asbtract ( 0 )  

This study was conducted in the riparian forest of Erdaobaihe River, and the flora of riparian plant communities on the northern slope oi Changbai Mountain was researched and analyzed.There were 288 vascular plant species belonging to 169 genera and 68 families, among them, 26 plant species belonging to 16 genera and 11 families were fern, and 262 plant species belonging to 153 genera and 57 families were spermatophyte.Among spermato-phyte, there were 9 gyrnnosperm species belonging to 6 genera and 3 families and 253 angiosperrn species belonging to 147 genera and 54 families.Among angiosperrn, there were 212 dicotyledonous species belonging to 118 genera and 45 families and 41 monocotyledonous species belonging to 29 genera and 9 families.All the results showed that there were abundant plant species in the riparian plant communities on the northern slope of Changbai Mountain.Analyses on the distribution area types of spermatophyte in the riparian communities showed that the distribution area types of genera and families were both abundant.For genus level, there were 9 distribution area types and 7 sub-types, and for family level, there were 6 distribution area types and 2 sub-types.The riparian plant communities had a temperate characteristic, and there were 117 genera, which were accounted for 76.5% of all the genera of spermatophyte, belonging to all the different temperate distribution types.In addition, the flora of riparian communities had a complex component, and had close relations with Tropical and East Asia distribution type, but few relations with Mediterranean distribution type.The results also showed that riparian zone could play an important role in biodiversity protection.

Hydraulic characters of Acer truncatum seedlings

ZHAI Hongbo, LI Jiyue

2003, (9):  1411-1415. 

Asbtract ( 0 )  

The hydraulic parameters of 4 years old Acer truncatum seedlings were measured by improved flushing method under the condition of controlled drought gradients in the greenhouse.It's indicated that the changes of hydraulic parameters with stem segment functional xylem diameter could be modeled by different equations.The hydraulic conductivity was influenced by the area that stem segment located.It was higher in non-constriction area than in constriction area.The existence of constriction area was in favor of the competition between individual seedlings.Hydraulic conductivity, specific conductivity and leaf specific conductivity were proportional with functional xylem diameter and twig water potential.The leaf specific conductivity of thicker branches was far higher than that of distal twigs, which was in favor of seedlings in saving those organs with more photosynthesis devotion during drought stress.The change of Huber value of same diameter branches with twig water potential was very small before defoliation, and hence, the main source of seedling's water stress came from xylem cavita-tion and embolism.

A comparative study on seed germination of15 grass species in Keeqin Sandyland

LIU Zhimin, LI Xuehua, LI Rongping, JIANG Deming, Cao Chengyou

2003, (9):  1416-1420. 

Asbtract ( 0 )  

Alaboratory study was made on the germination characteristics of freshly-collected seeds of grass species at the Wulanaodu area of Keeqin Sandyland in Eastern Inner-Mongolia.Of the 15 species examined, 8 species including Clinelymus dahuricus,Cleistogenes squarrosa,Pappophorum boreale,Spodiopogon sibiricus, Phragmites communis, Chloris virgata, Arundinella hirta, Pennisetum alopecuroides had a germination rate of over 80 %,but 4 species including Echinochloa hispidula.Hemarthria compressa, Tragus berteronianus and Setaria viridis had a value of less than 10% .Spodiopogon sibiricus, Eragrostis pilosa, Phragmites communis, Chloris virgata, Clinelymus dahuricus, Pappophorurn boreale, Digitaria cilliaris and Cleistogenes squrrosa began to germinate within 1～3 days after the test began, while Setaria viridis, Tragus berteronianus and Hemarthria compressa failed to germinate in a period of more than10 days.For the species such as Digitaria cilliaris, Echinochloa hispidula, Phragmites communis, Eragrostis pilosa and Spodiopogon sibiricus, their germination period was less than10 days, while Clinelymus dahuricus and Pappophorum boreale had a germination period of more than 20 days.The days required for half the final germination rate to be reached were; 2 days for Chloris virgata, 3 days for Phragmites communis, 4 days for Spodiopogon sibiricus, 5 days for Clinelymus dahuricus and Cleistogenes squarrosa, 7 days for Arundinella hirta and Pappophorum boreale, and 10 days for Pennisetum alopecuriodes.Compared with the Sheffield region in Britain, the Wulanaodu area of Kerqin Sandyland had a higher proportion of annual grasses with a low germination rate and a longer germination period, and the perennial grasses at the Wulanaodu area had an approximately same germination rate, but a longer germination period.During germination,ruderals showed the potential for risk-sharring, and thus, they had a relatively higher disturbance-resistance capacity.

Gap edge effect of Castanopsis kawakamii community

LIU Jinfu, HONG Wei, LI Junqing, LIN Rongfu

2003, (9):  1421-1426. 

Asbtract ( 0 )  

This paper reported the characters of gap edge effect of Castanopsis kawakamii community in Sanming, Fujian Province.The species diversity, ecological dominance, and edge effect strength of 38 forest gaps with different development stages in different stands of Castanopsis kawakamii community were measured, and Shannon-Wiener index, Simpson index, and index of edge effect strength were calculated.The results showed that the index of the gap edge effect of Castanopsis kawakamii community was about 0.7～1.3 (according to the species diversity index) and 0.3～1.8 (according to the ecological dominance index).The gap edge effect had the trend of increasing the species diversity of forest communities.The index of gap effect was affected by the size and development stage of the gap and the related forest type.The study provided a theoretical basis for the maintenance of species diversity and the forest management in Castanopsis kawakamii community.

Population dynamics of Quercus variabilis on northern slope of Qinling Mountains

ZHANG Wenhui, LU Zhijun, LI Jingxia, LIU Guobin

2003, (9):  1427-1432. 

Asbtract ( 0 )  

Studies on the population dynamics, age structure, spatial distribution pattern, life table, and survival curve of Quercus variabilis showed that the Q.variabilis population on the northern slope of Qinling mountains was increasing.The number of young - aged individuals was larger, and that of middle-aged and old individuals was smaller.The life tables for different age classes showed that the mortality at age classes Iand IIwas the highest, and the mortality rate was decreased with increasing age.However, at age classes VIIand VIII, the mortality rose again for their decrepitude.The expected life span of age classes III, IVand Vwas higher, and decreased gradually with increasing age.The survival curves were the type of Deevey III, and the distribution pattern of population was aggregative as a whole.As the age increased, the intensity of aggregation decreased, and tended to a random distribution at higher elevations.Awise management should accelerate the recovery of Q.variabilis population and the enhancement of its productivity.The altitude 800～1100 m was the favorable habitat for Q.variabilis population.As for the Q.variabilis at lower altitude, its protection should be reinforced, and the disturbance from human beings should be reduced.Forest thinning and other fostering management at middle altitude should be given in time.The target trees at higher altitude should be fostered.

Evaluation on sustainability of forest resources in Bailong River forest region, Gansu Province

GUO Zhenggang, CHENG Guodong, WU Bingli, CHEN Yuqi, SUN Xuegang

2003, (9):  1433-1438. 

Asbtract ( 0 )  

Based on the theories of sustainable development of forest resources, this paper constructed an index system for the integrative evaluation on the sustainability of forest resources in Bailon River forest region of Gansu Province.After calculated the index values of five strategic levels and twenty measure levels, the degree of harmony (DH) was obtained, with which, the sustainability of test forest resources could be evaluated.The DH value was 0.5320 in 1996 and 0.6100 in 2000, which was smaller than the theoretic value of 0.7000, and hence, this forest region belonged to non-sustainable development, but made some progress for its sustainability.

Ecological restoration effects of typical manmade ecosystems and relationships between restoration variables in middle Yunnan area

WANG Zhenhong, DUAN Changqun

2003, (9):  1439-1445. 

Asbtract ( 0 )  

This paper studied the restoration effects of Pinus yunnanensis forest, mixed Eucalyptus maideni-Acacia meam-sii forest, Eucalyptus maideni forest and restored natural vegetation in middle Yunnan area.The man-made forests consisting of different tree species had different effects on plant diversity, forest hydrology, soil surface erosion control, soil amelioration, and forest characteristics.Afforestation with native species promoted the plant diversity.Recovery Distance Index(RDI) was calculated for the evaluation of the forest restoration extent based on Principal Component Analysis (PCA).The restored natural vegetation P.yunnanensis forest, E.maideni forest, and A. mearnsii-E. maidensi forest would need correspondingly 29.14, 14.36, 34.23, and 11.03 years to recover to the ecological functions of zonal climax community.There were some relationships among forest recovery variables.Shannon-Wiener index, herbage coverage, community evenness, species diversity, soil available K, soil bulk density, biomass of herbage, woody plant coverage, timber volume of woody plant, soil total K, soil erosion, soil Si/V, littersfall, soil non-capillary porosity and through-fall were the main variables among the forest restoration variable dealt with in our work.Diversity played a central role in the restoration of ecosystem structure and functions.

Eco-physiological responses of Picea mongolica ecotypes to drought stress

ZOU Chunjing, HAN Shijie, XUWenduo, LI Daotang

2003, (9):  1446-1450. 

Asbtract ( 0 )  

The seedlings of different Picea mongolica ecotypes were treated with drought stress, and their height growth, MDA, proline, and chlorophyll content were investigated.The results showed that the height growth was obvi-ously reduced by drought stress.With sufficient water supply, the height growth of f.viridis W.D.Xu f.nov Picea mongolica was rapid and obviously better than that of f.purpurea W.D.Xu f.nov Picea mongolica, but was obviously reduced by intense drought stress.Furthermore, drought stress shortened the annual growth period of Picea mongolica, and made its terminal hud formation more than one month earlier, increased in both needles and roots, but was higher in needle than in root.The MDA content was higher in Picea mongolica than in f.viridis W.D.Xu f.nov Piburcea mongolica, and the proline content in needles was increased with increasing drought stress, hut in roots, the proline content was higher in f.viridis W.D.Xu f.nov Picea mongolica than in f.purpurea W.D.Xu f.nov Picea rnongolica and f.rubra W.D.Xu f.nov Picea mongolica.The latter 2 forms showed a similar trend in chlorophyll content.Their chlorophyll a, chlorophyll b and total chlorophyll contents increased at the beginning of drought treatment, and then decreased with increasing drought stress.The chlorophyll content of f.viridis W.D.Xu f.nov Picea mongolica decreased with drought stress.The ratio of chlorophyll a/b decreased from maximum to minimum in f.viridis W.D.Xu f.nov Picea mon-golica,but decreased in a relative small extent in f.purpurea W.D.Xu f.nov.It's proved that f.purpurea W.D.Xu f.nov Picea mongolica had a larger drought-resistance capacity than f.viridis W.D.Xu f.nov, and f.rubra W.D.Xu f.nov was a typical transitional ecotype from f.purpurea W.D.Xu f.nov to f.viridis W.D.Xu f.nov.

Succession pattern of artificial vegetation community and its ecological mechanism in an arid desert region

XU Cailin, LI Zizhen

2003, (9):  1451-1456. 

Asbtract ( 0 )  

Focusing on the artificial vegetation protection system of the Shapotou section of Baotou-Lanzhou railway in the arid desert region of China, this paper examined the dynamics of dominant plant species and the succession pattern of artificial plant community in the process of establishing and developing regional artificial vegetation.It also studied the driving force and the ecologically intrinsic mechanism of the community succession.The results demonstrated that the species composition of the artificial vegetation dramatically changed after 40 years of succession, from original artificial plant community of shrub and semi-shrub to artificial-natural desert plant community with annual herb dominated.During the process of succession, the importance values of artificial shrubs, such as Caragana korshinskii and Hedysarum scoparius, decreased and gradually retreated from the artificial plant community, while the naturally multiplied annual herb, such as Eragrostis poaeoides, Bassia dasyphylla, Salsola ruthenica, Chloris virgata and etc., were presented one after another and gradually became dominant.Besides, Artemisia ordosica always played a key role in the community due to its ability of naturally sowing and self-replacement.This type of succession pattern was closely related to the shortage of precipitation resource in this region and the formation of soil crust which inhibited the reproduction of shrub and perennial herb with deep root systems.This study provided a theoretical ground for realizing persistent development of artificial plant community.

Soil seed banks of different grassland types of Alashan arid desert region, Inner Mongolia

ZENG Yanjun, WANG Yanrong, NAN Zhibiao, WEI Dong, CHEN Shanke, LI Baoer

2003, (9):  1457-1463. 

Asbtract ( 0 )  

Investigations on the soil seed banks of different grassland types of Alashan arid desert region in Inner Mongolia showed that when the altitudes of sampling plots increased from 1370 m to 1750 m, the soil seed densities of natural grasslands decreased from 326 grain·m^-2 to 76 grain·m^-2.At the altitude of 1100 m, the soil seed density was 56 grain·m^-2 in typical desert plot, but only 8 grain·m^-2 in the sand dune plot.After the vegetation was restored with Artemisa sphaerocephala on sand dune, its soil seed density increased obviously, almost as 17～29 times as sand dune's.In this study, 31 seeds m^-2 were sampled, which belonged to 11 families.Among them, annual plants accounted for 77%, 100% and 70%, perennial plants accounted for 21%, 0 and 16%, and semi-shrubs accounted for 2%, 0 and 14%, respectively for natural grassland, sand dune and sown grassland.Shrub seeds were not found in all the soil seed bank plots.When the altitudes of sampling plots increased from 1100 m to 1750 m, the species richness (Margalet index) of soil seed banks of natural grasslands increased from 1.49 to 2.77, and the species diversity (Shannon-Winner index) increased from 0.697 to 0.917.

Landscape structure and ecological coupling analysis of ecotone on the west Sonnen Plain

SONG Changchun, DENG Wei, SONG Xinshan

2003, (9):  1464-1468. 

Asbtract ( 0 )  

Ecotone is a special zone in the landscape, which is very susceptive to the changes in environmental conditions, and hence, is prone to the disturbance by unfavorable conditions.Human activity has a series of positive and negative effects on it, and greatly changes the geo-chemical process in the ecosystem.In the ecosystem, especially in the ecotone, different systems and regimes are interconnected and inter-determined.For the sustainable development of ecosystem and the protection and rational utilization of resources, it is of great importance to study this internal relationship and to seek rational regulation and control measures.With the ecotone in the west Songnen Plain as an example, and based on the studies of the topography, physiognomy, soil, vegetation, and their geographic distribution in the ecotone.,this paper explained the structure of the ecological landscape, and quantitatively analyzed the ecological geo-chemical processes under different landscape conditions.In addition, this paper also tried to make coupling analyses to the ecologic succession and the landscape geo-chemical environment.Under current conditions, the succession of plant communities and the shift of soil landscape geo-chemical conditions in the west Songnen Plain are almost coinstantaneous, and these two factors can inter-determined under certain conditions.

Dynamics of atmospheric6 ¹³C in the past 440 years in Aleitai, Xinjiang

CHEN Tuo, QIN Dahe, LIU Xiao-hong, REN Jiawen, LI Jiangfeng

2003, (9):  1469-1472. 

Asbtract ( 0 )  

Since industrial revolution, a large amount of anthropogenic CO₂ from fossil fuel combustion and deforestation has been emitted into atmosphere, and thus, the atmospheric CO₂ concentration increased rapidly, while the δ¹³C in atmospheric CO₂ became lower and lower due to Suess effect.Therefore, the prediction of δ¹³C is crucial for studying global changes.In order to make an accurate prediction, it is necessary to understand its historical variation.The dynamics of δ¹³C in plants can sensitively reflect it.In this paper, the dynamics of δ¹³C in atmospheric CO₂ in the past 440 years in Aleitai, Xinjiang were reconstructed by using tree-ring δ¹³C series and plant stable carbon isotope fractionation model.The results showed that atmospheric δ¹³C value was relatively constant before 1850 (R²=0.052), which was about -6.60‰, while a sharp decrease in atmospheric δ¹³C with an average of - 7.02‰ was found since 1850 (R²=0.65).Compared with those from ice core bubbles, more fluctuations were found in atmospheric 8 Cderived from tree-ring series, possibly due to the higher resolution of the latter, and the difference of real atmospheric δ¹³C between the growth site of the tree and the globe.

Application of ISSR technology in genetic diversity detection of Jute

QI Jianmin, ZHOU Dongxin, WUWeiren, LIN Lihui, WU Jianmei, FANG Pingping

2003, (9):  1473-1477. 

Asbtract ( 0 )  

The genetic diversity among 27 accessions of Corchorus, including 10 Jute species, was investigated with ISSR technique.283 DNA bands were amplified with 25 ISSR primers, among which, 263 (92.85%) were polymorphic, with 10.48 bands per primer in average.Afurther systemic cluster analysis indicated that the accessions could be clustered into three groups, and the group Ⅱ (including two cultispecies and their close wild species) was obviously genetically different from the groups I and Ⅲ (including eight wild species).Moreover, 16 accessions in group Ⅱ presented a higher intraspecific genetic resemblance, while 11 accessions among groups I & Ⅲ showed an abundant interspecific genetic diversity.After synthesized the relevant findings of morphology and DNA classification, it's found that C.urticifolius could be one of the original wild species, C.tilaculariszic was a variation of C.tilaculari, and Tian Jute could be an untitled wild species.

Interrelationship between water use efficiency and nitrogen use efficiency of different wheat evolution materials

LI Yangyang, ZHANG Suiqi, SHAO Mingan

2003, (9):  1478-1480. 

Asbtract ( 0 )  

Afield micro -plot experiment on the interrelationship between water use efficiency and nitrogen use efficiency of different wheat evolution materials at the whole plant level showed that both water and nitrogen use efficiency increased gradually during the long evolution process from diploid to hexaploid.The water use efficiency was positively related with nitrogen use efficiency across nine evolution materials excluding French S.cereals, suggesting that the high nitrogen use efficiency of French S.cereals might be related with physiological mechanisms other than WUE.

Niches analysis of three aphid populations on spring sowing maize

DING Wei, ZHAO Zhimo, WANG Jinjun, CHEN Guihong

2003, (9):  1481-1484. 

Asbtract ( 0 )  

Systematic analysis of aphid populations and niches patterns on spring sowing maize was carried out during 1998～1999 in the suburbs of Chongqing.The results indicated that there were three aphid populations Rhopalosi-phum maidis Fitch.,Rhopalosiphum padi Linn, and Sitobion avenae Fahricius distributed on the spring sowing maize.The mixed aphid populations traded off during the growth period of spring sowing maize, and two peaks of quantitative counts were shown at the mid and last ten days of May and the last ten days of June.In addition, the niches of aphid population were also discussed from one dimension (i.e., temporal or spatial) to two dimensions (i.e., temporal and spatial).Through the quantitative analysis of niche breadth and niche overlap, the highly temporal differentiation of M.avenae and the highly gathering character of R.maidis were all indicated. R.padi showed an indistinct differentiation, while R.maidi was a dominated population on the spring sowing maize.

Three-dimentional distribution pattern dynamics of Erythroneura sudra and its natural enemy Erigonidum graminicola

ZOU Yunding, ZHOU Xiazhi, BI Shoudong, LI Lei, GAO Caiqiu, DING Chengcheng

2003, (9):  1485-1488. 

Asbtract ( 0 )  

Investigations on the Erythroneur sudra and Erigonidum graminicola populations in three layers (upper, middle and lower) and four directions (east, south, west and north) of peach tree crown showed that both of them had aggregated spatial distributions in these 7 part, because 5 parameters used to analyze the distribution reached required standard.Each insect was attracted by the others, as the parameter (a) in Iwao formulation m^*= a +Bx-(1971) was positive.The average density of aggregation was the biggest in its middle layer and east direction, and the smallest in its lower layer and south direction .The biggest average density of aggregation appeared in mid-September.

Soil organic carbon pool and its spatial distribution pattern in the Circum Bohai Region

LIU Guohua, FU Bojie, WU Gang, DUAN Guilan

2003, (9):  1489-1493. 

Asbtract ( 0 )  

The research and management of soil carbon pool and the effect of land-use on it are the key project of study on global change.In this paper, the data of 1374 soil profiles in the Circum Bohai Region were used to estimate the soil organic carbon (SOC) pool of this region.The results showed that in this region, the total soil organic carbon pool in1m depth was 2.1 Pg C, and the biggest SOC pool was brown soil, occupying55.6 % of the total SOC.The second one was moisture soil, accounted for 26.9 % .The SOC pools of aeolian sandy soil and dark brown soil were very small, only about 0.1% of the total.However, the soil organic carbon density (OCD) of boggy soil was the biggest (22.90 kg C穖^-2), the second was dark brown soil (16.04 kg C穖²), and the lowest were aeolian sandy soil (2.88 kg C穖^-2) and solonchak (6.0 kg C穖^-2), implying that desertification and salinalization could reduce soil organic carbon.Moreover, the results also suggested that the topsoil held 673.30 Tg C.It meant that there was about one-third of the total SOC could be easy to be disturbed.According to the OCDat its level distribution gradient, it could be divided into four regions, i.e., coastal region, plain region, northwestern region, and hilly region.The order of OCD from high to low was hilly region, northwestern region, plain region, and coastal region.This regulation reflected not only the role of climate and landform, but also the effect of human activity intensification on SOC.Therefore, it was very important to protect and manage the land in this region well for the SOC maintenance and the sustainable land use.

Spatial distribution characteristics and ecological effects of carbon and nitrogen of soil in Huolin River catchment wetland

BAI Junhong, DENG Wei, ZHU Yanming, LUAN Zhaoqing, ZHANG Yuxia

2003, (9):  1494-1498. 

Asbtract ( 0 )  

This paper studied the spatial distribution characteristics and ecological effects of organic carbon and nitrogen in soils of Huolin River catchment wetland in horizontal and vertical levels.The results showed that the differences of horizontal and vertical distribution of organic carbon and nitrogen were very obvious, and of all the factors such as the period of wetting and drying cycles, leaching, plant and flood etc.,the period of wetting and drying cycles was contents the critical one, which caused the differences.Soil organic carbon was significantly correlated with soil nitrogen (r=0.977).The ratio of carbon and nitrogen (C/N) changed along with the humidity gradient, and soil pH values obviously influenced the concentration of organic carbon and nitrogen.The correlation of C/N values and organic carbon and nitrogen contents in wetland soil and in grassland soil were remarkably different, and the ecological effects mainly included production effect and clarification effect.

Reserves and spatial distribution characteristics of soil organic carbon in Guangdong Province

GAN Haihua, WU Shunhui, FAN Xiudan

2003, (9):  1499-1502. 

Asbtract ( 0 )  

Soil organic carbon is the main part of terrestrial carbon reservoir and important part of soil fertility.The spatial distribution and reserves of soil organic carbon are very important for studying soil carbon cycle.According to the data from the second soil survey, soil organic carbon reserves was estimated and its spatial distribution was analysed by using GIStechnique.The results showed that the total amount of soil organic carbon is about 17.52×10⁸t.The carbon density of laterite, lateritic red soil and red soil in Guangdong Province is 8.83, 10.31, 9.15 kg·m^-2, respectively;lower than the mean carbon density of China.The carbon density of yellow soil and rice soil is 12.08, 12.17 kg·m^-2, respectively; higher than the mean carbon density of china.Soil carbon density is about 10.44 kg·m^-2 in Guangdong.The spatial distribution characteristic of soil organic carbon density in Guangdong is that the carbon density in south Guangdong Province is higher than that in north Guangdong Province, in that soil organic carbon density in north and middle Guangdong Province is 5～10 kg·m^-2 and in east Guangdong Province is 10～15 kg·m^-2.Soil organic carbon density mostly vary among 5～15 kg·m^-2.

Effect of nitrogen nutrition on endogenous hormone content of maize under soil drought conditions

ZHANG Suiqi, SHAN Lun

2003, (9):  1503-1506. 

Asbtract ( 0 )  

It is realized in recent years that roots play an important role in the control of shoot growth and development, not only because they can continuously provide the shoot with water and nutrients, but also because some chemical messengers are produced in roots to response soil drought stress and transported through transpiration stream to shoot where physiological processes are regulated.Extensive studies showed that the decrease of leaf conductance was closely related to the increase of xylem ABA concentration, suggesting that ABA can act as a water stress signal to regulate the physiological response of shoot.Fertilizer plays an important role in increasing crop yield and water use efficiency (WUE) on dry-land farming.It is not clear, however, whether the application of Nfertilizer can affect the root's signal intensity in drought stress and thus regulate its stomatal responses.Experiment with 3 water levels (35%,55% 和75%± 5% of field capacity) and 2 Nfertilizer levels (high Nand low N) was designed to investigate the effect of soil drought and Nnutrition on endogenous hormone concentration (ABAand ZRs) and stomatal conductivity of maize under potted conditions.The results showed that the application of Nsignificantly increased the stomatal conductivity of maize leaf under both drought and watered conditions.Meanwhile, it markedly decreased the ABAconcentration in root xylem sap, but increased ABA concentration in leaf of maize under soil drought conditions.The application of Ndecreased ZRs concentration in root xylem sap as well, which means that ZRs did not play a role in counteractive to ABA under soil drought conditions.The lower ABAconcentration in root xylem sap of high Nmaize rather than the higher ABA concentration in maize leaf accounted for the higher stomatal conductivity of high Nmaize leaf under soil drought conditions.

Parameters of energy flow in wheat - corn intercropping agroecosystem

WANG Jianlin, WANG Li, BAO Zaide, WANG Yuanlin

2003, (9):  1507-1511. 

Asbtract ( 0 )  

The parameters of energy flow of primary producers (agricultural crop and weed), consumers (pests and their natural enemies) and decomposer (soil microbe, protozoan and saprozoite) in wheat-corn intercropping agroecosystem in Tibet of China were studied by field investigation and laboratory measurement.The results showed that the wheat-corn intercropping agroecosystem had high primary productivity and energy translation efficiency, and the degression rate of energy flow through food chain was also high.At each nutritive layer of this agroecosystem, relatively less energy was required to product unit energy, and degree of energy utilization of superior nutritive layer from lower nutritive layer was increased gradually.

Effect of plastic film mulching on soil microbial biomass in spring wheat field in semi-arid loess area

SONG Qiuhua, LI Fengmin, LIU Hongsheng, WANG Jun, LI Shiqing

2003, (9):  1512-1516. 

Asbtract ( 0 )  

This paper studied the effect of different periods of plastic film mulching (M₀-no mulching, M₃₀-mulching for 30 days, M₆₀)-mulching for 60 days, and M-mulching for whole growth period) on soil microbial biomass carbon (SMBC) of spring wheat field in semi-arid loess plateau.The mean SMBC in 1999 and 2000 was 335.3 and 259.3 mg·kg^-1 dry soil, respectively.It was 29.3% higher in 1999 than in 2000.The highest SMBC was recorded at the harvest stage in Mtreatment for the two years.In1999, a wet year with more rainfall, the SMBC of M₆₀ and Mtreatments was significantly higher than those of M₀ and M₃₀ in the mid-period of growth, reached its top at the end of the growth period.The highest grain yield was also achieved in M₆₀.It was a dry year in2000, but rainfall was rich in the latter growth period of spring wheat.SMBC increased at the beginning period of growth, and did not increase during the mid-growth period.It increased again during the latter period of growth, and showed a significant difference among the treatments.At the harvest stage of 2000, SMBC in M₀ was the highest among all the treatments.It was similar between Mand M₆₀, and lower than that of M₃₀.In the two years, the ratio of C/N ranged between 7.732～9.042, being lower than the threshold of 11.3, and the ratio of C/P was 300.8～719.6, being higher than the threshold of 300.The two parameters showed that the increase of SMBC was inhibited because of the competition of soil available nutrients between soil microbes and crops.These indicated that soil organic matter content was so shortage that it became the key factor to restrict crop productivity.Under this condition, increasing crop productivity through the input of chemical fertilizers would conceal the problem of soil degradation, and result in a further decrease of soil quality.Along term plastic film mulching would make the problem more serious.

Effect of Sinorhizobium fredii YC4 symbiotic plasmid amplification on nod factors and symbiotic N-fixation

MIAO Lihong, ZHOU Junchu

2003, (9):  1517-1520. 

Asbtract ( 0 )  

Sinorhizobium fredii YC4 can form nitrogen-fixing nodules on soybean (Glycine max) and wild soybean (G.soja).It can produce unique lipochitooligosaccharide nod factors (LCOs), in comparison with the other four strains of S.fredii.The constitution of LCOs produced by YC4 contained more hydrophobic substitutions detected by Thin-layer chromatography (TLC) of ¹⁴C-labeled nod factors.Aspontaneous mutant termed YSC3 amplified in the symbiotic plasmid was isolated from YC4, which can produce more amount of LCOs than its parental strain at 28 ℃,and showed a difference in the construction of LCOs.Nodulation test indicated that YSC3 only formed ineffective nodules on soybean G.soja.

Identification on an antagonistic rhizobacterium X3 from rhizosphere of cucumber

SHEN Aihua, ZHANG Bingxin, LI Bin, SHEN Lirong, YU Jingquan

2003, (9):  1521-1524. 

Asbtract ( 0 )  

Classical physiological and biochemical methods, Biolog, and 16SrDNAanalysis were used to identify the strain X3 which could control cucumber seedling damping-off.Physiological and biochemical identification showed that it belonged to Pseudomonas aeruginosa, but Biolog identification showed it was P.spinosa.16SrDNA determination and analysis was used for further identification, which showed that the 16SrDNA sequence of X3 shared 93.7% homologies with published sequence of P.aeruginosa from GenBank, and both sequences constituted a branch in Phylogenetic tree.Based on these results, it is considered that the strain X3 belongs to one strain of P.aeruginosa.

Effect of environmental factors on the growth and fatty acid composition of five endophytic fungi from Sapium sebiferum

DAI Chuanchao, YU Boyang, XU Zenglai, YUAN Sheng

2003, (9):  1525-1528. 

Asbtract ( 0 )  

Five fungi species including Rhizoctonia sp.,Sclerotium sp., Acremoniell sp., Chaetomium sp.and Pestalo-tiopsis sp.screened from the inner bark of Sapium sebiferum (Level) Roxb.were used to study their growth under different environmental factors, with the biomass and fatty acid composition as main indexes to elucidate the relationship between plant and its endophytic fungi.Compared with that from synthesized medium, a higher biomass was harvested when the fungi were cultured on liquid potato dextrose medium; the unsaturation index of fatty acid (IUFA) was lower, and the main fatty acids in the fungi were linoleic acid, palmitic acid and oleic acid.Compared with the fungi grown on the synthesized medium without Sapium sebiferum' s extract, the Sclerotium sp.growth was promoted, and the others were inhibited when the extract was added to the synthesized medium.At the same time, the IUFA were increased.When0～1.0 mol·L^-1 NaCl was added in Sclerotium sp.'s culture medium, the biomass was not changed notably; IUFA in 0～0.5 mol·L^-1 NaCl was not significantly different, while in the range of 0.6～1.0 mol·L^-1 NaCl, the IUFA was decreased with increasing concentration of NaCl.It indicated that fungus had a stronger tolerance to salt.Sclerotium sp.'s growth was promoted, and the IUFA was increased when plant oil was added in the synthesized medium.The biomass was the highest by adding1.5% plant oil.The results mentioned above were some way related to the symbiotic relations between the endophytic fungi and their host plant.

Effect of enhanced ammonium nutrition on photosynthesis and nitrate reductase and glutamine synthetase activities of winter wheat

DAI Tingbo, CAO Weixing, SUN Chuanfan, JIANG Dong, JING Qi

2003, (9):  1529-1532. 

Asbtract ( 0 )  

Acontrolled hydroponics experiment was conducted to investigate the effects of three NH₄⁺/NO₃^- ratios (0/100, 50/50 and 100/0) on the photosynthesis and the key nitrogen metabolism enzymes of three wheat cultivars with different sensitivity to enhanced ammonium nutrition (EAN).Compared with NO₃^- alone, EANsignificantly increased the leaf chlorophyll content, net photosynthetic rate, and soluble sugar content.It also significantly increased the soluble protein content in leaves and roots and the nitrate reductase activity in leaves, but had no significant effect on Glutamine synthetase (GS) activity.EANincreased the soluble sugar content in leaves, and correspondingly, enhanced the net photosynthetic rate and maintained a higher soluble sugar/protein in leaves and roots, which was favorable to the nitrogen assimilation and plant growth.

Optimum soil water supply range of Malus pumila

WANG Keqin

2003, (9):  1533-1537. 

Asbtract ( 0 )  

By means of the determination of net photosynthetic rate and transpiration rate of the leaves of seven-year field and two-year spotted Malus pumila(Goldspur) under different soil water contents and illumination and calculation of water use efficiency (WUE), the optimum soil water supply range of Malus pumila was determined.The results showed that: because photosynthetic advantageous radiation (PAR) and soil water content (SWC) decided the value of photosynthetic rate and transpiration rate of Goldspur, thus they influenced the value of WUE.The response of WUE to illumination had relations with soil water.When SWC was 10% (50% of field capacity-FC) or so, the maximum of WUE was the highest value among all the soil water treatment and reached about 230 umol CO₂·g^-1 H₂O.When the water supply was adequate (SWC>15% ), the maximum was only 160 umol CO₂·g^-1H₂O or so, the difference between each SWC level was not obvious and simulated curve fundamentally overlapped, although WUE decreased slowly after reached the maximum.The variation of WUE with SWC had relations with illumination.WUE was the highest while PAR was in the range of 500～1 000 umol.m^-2.s^-1).Because the state of soil water decided the values of stomatic resistance (RS) and leaf water potential, RS and Ψ₁ also had influence on the changes of WUE.When RS and Ψ₁ were respectively 2.0 s·cm^-1 and -3.0 MPa, WUE was the highest, but Pn was relatively low, which was not good to the normal growth and fruitage of trees.From the overall consideration of WUE, Pn and Tr, the scopes of RS and Ψ₁ were 2～6 s·cm^-1 and -2.1～-1.65 MPa, respectively, which not only guaranteed the normal photosynthesis of Goldspur, but also benefited the increase of WUE.The scope of the corresponding SWC was 11%～15%,which was equal to 55%～75 % of FC and this scope could be used as theoretical index of field water supply for Goldspur.

Reproductive biology of Macrobrachium nipponensis in Lake Wuhu

HE Xugang, GONG Shiyuan, ZHANG Xunpu, LIU Jun, HU Qiuyuan, WANG Honghui, TAO Renyong

2003, (9):  1538-1542. 

Asbtract ( 0 )  

Macrobrachium nipponensis is a key species of freshwater shrimps in China.To know its reproductive biology is very important for its protection and rational use.Studies from September 1998 to September 1999 in Lake Wuhu showed that the spawning ground of M.nipponensis was situated in the littoral zone of the whole lake.The main spawning period of overwintering shrimps was from mid-April to mid-July (water temperature 20.5～31℃), and that of non-overwintering shrimps was from mid-July to mid-September (water temperature 31～23℃).The sex ratio(♀:♂)increased gradually during the spawning period, and the absolute fecundity of overwintering shrimps was higher than that of non-overwintering ones.The relationship between absolute fecundity and body length and between absolute fecundity and body weight could be expressed as cubic equation and simple linear equation, respectively.The relative fecundity (R_w) of M.nipponnensis could regard as a constant, and its 95% confidence limits was 1067.76±16.94 eggs·g^-1.

Dynamics of dry deposition velocities (V_d) of atmospheric SO₂ on rapeseed/rice rotation systems in selected area of South China

HU Zhengyi, XU Chengkai, CAO Zhihong, WANG Tijian, ZHAO Yanwen

2003, (9):  1543-1546. 

Asbtract ( 0 )  

With the profile meteorological data collected from the farmland micro-meteorological experimental substation, Experiment Station of Red Earth Ecology, Yingtan, Jiangxi, Chinese Academy of Sciences during rapeseed/rice rotation from Nov.1998 to Oct.1999, the surface layer turbulence characteristic parameters (u^*,θ^*,L) and the atmospheric SO₂ dry deposition velocities (V_d) were calculated.The results indicated that the hourly mean V_d of SO₂ dry deposition was ranged from 0.124 to 0.897 cm·s^-1 (mean±SE = 0.507±0.167 cm·s^-1), and its regular dynamic pattern was as follows: it was always higher at daytime than at night, and the mean V_d of SO₂ dry deposition during March-August(0.611 cm·s^-1) was obviously greater than that during Sept.- Dec.and Jan.-Feb.(0.401 cm·s^-1).The mean V_d of SO₂ dry deposition during various crop growth stages was decreased as the order of rice (0.605±0.093 cm·s^-1) > rapeseed (0.491±0.166 cm·s^-1) > follow (0.342±0.174 cm·s^-1).

Effects of simulated acid rains on Cd, Cu and Zn release and their form transformation in polluted soils

GUO Zhaohui, HUANG Changyong, LIAO Bohan

2003, (9):  1547-1550. 

Asbtract ( 0 )  

The release and form transformation of Cd, Cu, and Zn in polluted red soil and yellow red soil affected by simulated acid rains were studied through batch equilibrium experiments.The results showed that the release of test heavy metals increased significantly with decreasing pHvalue of simulated acid rain.Their release amount was negatively correlated to the pHvalue of acid rains.In polluted red soil and yellow red soil, Cd existed mainly in exchangeable form, and Cu in organically bound and Mn oxide-occluded forms.Zn existed mainly in residual and exchangeable forms in polluted red soil, and in residual and organically bound forms in polluted yellow red soil.To some extents, the release of Cd, Cu and Zn and the chemical forms of Cd and Zn in test soils were affected by soil organic matter content and CEC.The release amount of bio-available Cd and Cu in polluted red soil and yellow red soil was increased greatly with the increasing acidity of simulated acid rains, but the transformation of Zn from stable to bio-available form was not obvious.

Several problems in ecological security assessment research

WANG Genxu, CHENG Guodong, QIAN Ju

2003, (9):  1551-1556. 

Asbtract ( 0 )  

Ecological security assessment is the identification and judgment of ecosystem completeness and sustainable ability to maintain ecosystem health under all kinds of risks, the core contents of which are ecological risk assessment and ecological health assessment.Ecological risk identification and ecological vulnerability are the composing elements of ecological risk assessment, while ecological health includes three aspects, i.e., ecological completeness, ecosystem vigor, and ecosystem resilience.In the studies of ecological security assessment, the rational combination of ecological risk and ecological health, and the establishment of integrated measure index system based on confirming spatial scale are needed.At present, risk factor identification index, exposure analysis index, and influence (response) analysis index are the broader construction systems of ecological risk index.Nevertheless, on the basis of the classification of EDI, REI and IRI, the method of superimposing exposure analysis index may be the development direction of establishing index system in the future.Among the methods of quantificational assessment, exposure-response analysis was one of the most extensive method used at present, but ecological model method to assess different-scale ecological security will be the main development field, and focused on the security of ecological processes in the future.Ecological security assessment must be intergraded with ecological prediction, security guarantee and management.

Application of mist net in studies of forest bird communities

ZOU Fasheng, CHEN Guizhu

2003, (9):  1557-1560. 

Asbtract ( 0 )  

It had been more than twenty years for using mist net to study forest avian community.Mist net was very useful for studying cryptic, less vocal or non-vocal, and non-territorial birds, particularly understory birds in forest.The accuracy of mist net was relatively independent of observer biases and skills.It allowed identical and simultaneous sampling of numerous sites and straightforward comparisons among studies done at different sites by different people.So, a lot of ornithologists considered it as a necessary way for studying forest bird communities.Few studies had been reported on bird communities by using mist nets in China.In this paper, some examples on studying forest bird community by using mist nets were introduced, and studies on forest bird community with mist net should be used widely in China in the future.

Ecological protection of medicinal woody plants

YAN Xiufeng

2003, (9):  1561-1564. 

Asbtract ( 0 )  

Medicinal woody plants, especially medicinal tall trees, play a same important role in forest structure, ecological balance and timber production as other tree species in forest, and due to their additional medicinal values overuse of these trees is more intensive than others.Many medicinal materials are destructively obtained from plants such as roots or bark used as medicinal materials.The contradiction between the utilization and protection of medicinal woody plants becomes more and more incisive.In the present paper, based on the analysis of the utilized situation and specialty of medicinal woody plants, the trouble between the plants protection and utilization was observed, the method to solve it and the fundamental research work needs to be developed were discussed.The following aspects of researches were suggested to be conducted: (a) study on the distribution in organs, seasonal and age variations, and correlation with environmental factors of principal medicinal compositions in mature trees to clear the optimum of harvest and cultivation conditions; (b) study on the distribution in organs, seasonal and age variations, and correlation with environmental factors of principal medicinal compositions in saplings, especially the time course of the variation in medicinal compositions and biomass to achieve the optimal tree ages for the balance between biomass and production of medicinal products during saplings development; (c) study on the influence and regulation of environmental factors on medicinal compounds production in woody plants to look for the optimal cultivated conditions for optimizing the accumulation of biomass and medicinal chemicals; (d) further study on the regulatory mechanism of the induced production of main medicinal compositions by ecological factors at protein (key enzyme) and gene level to accumulate fundamental data for the enhancement of quality and quantity, and approach of new accesses to medicinal products using biological technology (cell culture and gene technology) .Aimed at medicinal woody plants in Chinese forest resources, to develop the fundamental researches on resources protection and rational utilization will create many profound scientific significances.Firstly, medicinal woody plants are the important components of Chinese natural forest resources, so the problem for their protection and utilization, especially for that of tall trees, is quite remarkable and special.To reveal the internal contradictory between plant resources protection and its reasonable exploitation and exploit a practicable access to solve it will promote and accelerate the fulfillment of "natural forest protection project" in China.Secondly, traditional Chinese medicine is a main part of Chinese excellent ancestral culture, and the traditional utilizing models have been carried on for thousands of years.Accompanying with the development of human society, many unavoidable troubles such as the shortage of natural resources and the pollution of natural environment are more and more severely, which make the old models of the traditional Chinese medicine become more and more harmful and inaccessible to mankind.New substitutive approach to the utilization of traditional Chinese medicine, especially to that of Chinese medicinal woody plants will be one of the key methods to improve the present situation.Thirdly, traditional Chinese medicine, the cherish treasure of Chinese ancestral culture, need not only be preserved but also be developed.One of the main problems to restrict the extensive spread of the traditional Chinese medicine is its unstable quality, so to reach the stable quality and good quality is tightly linked to the improvement of traditional Chinese medicine.Hence the environmental regulation to the cultivation of medicinal plants, which can prove and guarantee the stable and high quality, will fit the demand on the production of medicinal plant material, and correspond to the goal of great efficacy and superior quality during the course of modernization of traditional Chinese medicine.

Mycorrhizal diversity and its significance in plant growth and development

SHI Zhaoyong, CHEN Yinglong, LIU Runjin

2003, (9):  1565-1568. 

Asbtract ( 0 )  

Mycorrhizal diversity, including morphological, species and functional diversity, is an integrative component of biodiversities.Many experiments showed that mycorrhizal diversity played an important role in the origin, evolution, distribution, survival, growth and development of plants.But, mycorrhizal diversity is dependent on plant diversity.It was suggested that mycorrhizal and plant diversities stimulated or retarded each other.The significance of mycorrhizal diversity in plant diversity was also discussed.

Spatio temporal problems of geographic information system in marine fishery

SU Fenzhen, ZHOU Chenghu, DU Yunyan, ZHANG Tianyu, SHAO Quanqin

2003, (9):  1569-1572. 

Asbtract ( 0 )  

In marine fisheries, it is very important to understand and grasp the spatio-temporal nature.Geographical Information System (GIS) has been applied to describe or forecast the dynamic trend of resources or to set up evaluation model, which is one of high technologies in modern marine fisheries.Based on the review of the development of marine fishery GIS (MFGIS), four spatio-temporal problems it occurred were discussed, and the possible resolutions were prospected.

Several research hotspots in river ecology

CAI Qinghua, TANG Tao, LIU Jiankang

2003, (9):  1573-1577. 

Asbtract ( 0 )  

River ecology is a vital field in limnological research, and several new theories and methods have been developed and used in the study of lotic systems.In this article, a summary of these new theories was introduced, which includes river continuum concept, ecological water consumption of river ecosystem, services and health of river e-cosystem, ecosystem management, and watershed ecology.The authors suggested that the research of river ecology should be carried out on the scale of watershed, and that the combination of ecosystem health and ecosystem services could be the key point in the sustainable development management of river ecosystem.Seeing that there are few studies in this area in China, relevant research should be conducted as soon as possible.

Ecological studies on genetically engineered microorganism in environment

JIN Suying, ZHANG Jiazhi, DI Junyan

2003, (9):  1578-1580. 

Asbtract ( 0 )  

This paper discussed the main problems which should be considered on the environmental release of genetically engineered microorganism (GEM), including GEM construction, gene transfer, fitness, diffusion, translocation, potential eco-influence and so on.Moreover, aiming at the special ecological characteristic and eco-influence of GEM, this paper brought forward the policy of "respective analysis on different problems", and postulated the corresponding projects of GEM ecological research to apply GEM safely and effectively in nature.

Toxic effects of Cd²⁺ pollution on the biochemical and physiological characters and ultrastructure of Alternanthera philoxeroides

ZHOU Hongwei, SHI Guoxin, DU Kaihe, XU Qinsong, XU Nan

2003, (9):  1581-1584. 

Asbtract ( 0 )  

By imitating different concentration Cd²⁺ polluted water environment, this paper dealt with the changes of some biochemical and physiological characters and the damage of ultrastructure in leaves of Altemanthera philoxe-roides.The result showed that SOD and POD activity first increased in the low concentration pollution and then decreased with the concentration of pollution raised.The content of chlorophyll, chlorophyll a/b value, CATactivity and the content of soluble protein all declined continually.With the concentration of pollution increased, the ultrastructure of cell nuclei, chloroplast and mitochondria became deformed, the permutation of structure inside disordered, swelled, membrane disrupted and vesiculated.The changes of some biochemical and physiological characters accorded with the damage of cell ultrastructure.

Effect of bacterivorous nematodes on bacteria population under gnotobiotic culture

CHEN Xiaoyun, HU Feng, LI Huixin, MAO Xiaofang

2003, (9):  1585-1587. 

Asbtract ( 0 )  

Agnotobiotic microcosm experiment was conducted to study the influence of bacterivorous nematodes (Protorhab-ditis sp.) on bacteria (Pseudomonas fluorescens) population under different conditions including substrate concentration, oscillation pattern, and numbers of nematodes inoculated.When the bacteria were incubated under intermittent oscillation by hand (6 times at 0.5 h intervals, 22℃), their growth was stimulated in the presence of nematodes, and the bacteria grew faster with the increase of nematode numbers and substrate (liquid potato-sucrose medium) concentration.However, when the incubation was under continuous oscillation (100 rpm, 22℃), bacteria population was deflated with the addition of nematodes, and the inhibition was greater when a higher concentration of substrate was used.It was found that the stimulation or inhibition of bacteria population by nematodes occurred in the logarithmic stage of bacteria growth.The optimal and over-grazing of nematodes on regulating bacteria population was discussed.

Acute lethal and behavioral response of Liposcelis bostrychophila (Psocoptera: Liposcelididae) to DDVP

DING Wei, WANG Jinjun, ZHAO Zhimo, LI Xiaozhen

2003, (9):  1588-1590. 

Asbtract ( 0 )  

Book louse Liposcelis bostrychophila is a minor pest in stored products, and may seriously infest the stored products when its population outbreaks.This study was conducted to evaluate the toxic effect of DDVP on various development stages of L.bostrychophila.The results showed that at 28±0.5℃ and 24 h exposure under 75 %～80% RH, the LC₅₀ of the eggs, larvae of 1st to 4th stadium, and adults was 16.83, 0.22, 0.22, 0.23, 0.26 and 0.25 μg·L^-1, respectively.The lethal effect of DDVP on the adults at different exposure periods showed that their mortality was linearly related to the treated time, implying that the test colony of L.bostrychophila was susceptible to DDVP.In the practical fumigation, DDVP as a fumigant had a good effect on the pest control if the development stage, time and periods of treatment were appropriate.

Regeneration in gaps of the middle-mountain moist evergreen broad-leaved forest of Ailao Mountains

HE Yongtao, LI Guicai, CAO Min, TANG Yong

2003, (9):  1399-1404. 

Asbtract ( 962 )   PDF (790KB) ( 377 )  

On the basis of investigation on gaps in the middle-mountain moist evergreen broad-leaved forest of Ailao Mountains Natural Reserve, Yunnan Province, tree seedlings (H<50 cm) composition were compared in the gaps and the non-gap stand.The results showed that the dominant tree species of the forest were not preponderated over others in the gaps.The composition of tree seedlings in the gaps differed from those in the non-gap stand.The species diversity of tree seedlings in the gaps(H= 2.73, D = 0.89)were higher than those in the non-gap stand (H = 2.25, D=0.82), and the Jaccard correlative coefficient were only 0.6.The density of tree seedlings in the gaps (38636 N·hm^-2) was much higher than that in the non-gap stand (17323 N·hm^-2), of which many species were only found in the gaps.The dominant height of the tree seedling in the gaps and the non-gap stand were also 11～20 cm, but the percentage of the tree seedlings higher than 20cm in the gaps was significantly higher than that in the non-gap stand.The gap sizes had important impact on the tree seedling germination, and different species of tree seedling dominated in different size classes of gap.

Flora analysis of riparian plant communities on the northern slope of Changbai Mountain

DENG Hongbing, WANG Qingchun, DAI Limin, WANG Qingli, WANG Shaoxian

2003, (9):  1405-1410. 

Asbtract ( 1145 )   PDF (714KB) ( 347 )  

This study was conducted in the riparian forest of Erdaobaihe River, and the flora of riparian plant communities on the northern slope oi Changbai Mountain was researched and analyzed.There were 288 vascular plant species belonging to 169 genera and 68 families, among them, 26 plant species belonging to 16 genera and 11 families were fern, and 262 plant species belonging to 153 genera and 57 families were spermatophyte.Among spermato-phyte, there were 9 gyrnnosperm species belonging to 6 genera and 3 families and 253 angiosperrn species belonging to 147 genera and 54 families.Among angiosperrn, there were 212 dicotyledonous species belonging to 118 genera and 45 families and 41 monocotyledonous species belonging to 29 genera and 9 families.All the results showed that there were abundant plant species in the riparian plant communities on the northern slope of Changbai Mountain.Analyses on the distribution area types of spermatophyte in the riparian communities showed that the distribution area types of genera and families were both abundant.For genus level, there were 9 distribution area types and 7 sub-types, and for family level, there were 6 distribution area types and 2 sub-types.The riparian plant communities had a temperate characteristic, and there were 117 genera, which were accounted for 76.5% of all the genera of spermatophyte, belonging to all the different temperate distribution types.In addition, the flora of riparian communities had a complex component, and had close relations with Tropical and East Asia distribution type, but few relations with Mediterranean distribution type.The results also showed that riparian zone could play an important role in biodiversity protection.

Hydraulic characters of Acer truncatum seedlings

ZHAI Hongbo, LI Jiyue

2003, (9):  1411-1415. 

Asbtract ( 909 )   PDF (626KB) ( 269 )  

The hydraulic parameters of 4 years old Acer truncatum seedlings were measured by improved flushing method under the condition of controlled drought gradients in the greenhouse.It's indicated that the changes of hydraulic parameters with stem segment functional xylem diameter could be modeled by different equations.The hydraulic conductivity was influenced by the area that stem segment located.It was higher in non-constriction area than in constriction area.The existence of constriction area was in favor of the competition between individual seedlings.Hydraulic conductivity, specific conductivity and leaf specific conductivity were proportional with functional xylem diameter and twig water potential.The leaf specific conductivity of thicker branches was far higher than that of distal twigs, which was in favor of seedlings in saving those organs with more photosynthesis devotion during drought stress.The change of Huber value of same diameter branches with twig water potential was very small before defoliation, and hence, the main source of seedling's water stress came from xylem cavita-tion and embolism.

A comparative study on seed germination of15 grass species in Keeqin Sandyland

LIU Zhimin, LI Xuehua, LI Rongping, JIANG Deming, Cao Chengyou

2003, (9):  1416-1420. 

Asbtract ( 1223 )   PDF (604KB) ( 416 )  

Alaboratory study was made on the germination characteristics of freshly-collected seeds of grass species at the Wulanaodu area of Keeqin Sandyland in Eastern Inner-Mongolia.Of the 15 species examined, 8 species including Clinelymus dahuricus,Cleistogenes squarrosa,Pappophorum boreale,Spodiopogon sibiricus, Phragmites communis, Chloris virgata, Arundinella hirta, Pennisetum alopecuroides had a germination rate of over 80 %,but 4 species including Echinochloa hispidula.Hemarthria compressa, Tragus berteronianus and Setaria viridis had a value of less than 10% .Spodiopogon sibiricus, Eragrostis pilosa, Phragmites communis, Chloris virgata, Clinelymus dahuricus, Pappophorurn boreale, Digitaria cilliaris and Cleistogenes squrrosa began to germinate within 1～3 days after the test began, while Setaria viridis, Tragus berteronianus and Hemarthria compressa failed to germinate in a period of more than10 days.For the species such as Digitaria cilliaris, Echinochloa hispidula, Phragmites communis, Eragrostis pilosa and Spodiopogon sibiricus, their germination period was less than10 days, while Clinelymus dahuricus and Pappophorum boreale had a germination period of more than 20 days.The days required for half the final germination rate to be reached were; 2 days for Chloris virgata, 3 days for Phragmites communis, 4 days for Spodiopogon sibiricus, 5 days for Clinelymus dahuricus and Cleistogenes squarrosa, 7 days for Arundinella hirta and Pappophorum boreale, and 10 days for Pennisetum alopecuriodes.Compared with the Sheffield region in Britain, the Wulanaodu area of Kerqin Sandyland had a higher proportion of annual grasses with a low germination rate and a longer germination period, and the perennial grasses at the Wulanaodu area had an approximately same germination rate, but a longer germination period.During germination,ruderals showed the potential for risk-sharring, and thus, they had a relatively higher disturbance-resistance capacity.

Gap edge effect of Castanopsis kawakamii community

LIU Jinfu, HONG Wei, LI Junqing, LIN Rongfu

2003, (9):  1421-1426. 

Asbtract ( 974 )   PDF (715KB) ( 392 )  

This paper reported the characters of gap edge effect of Castanopsis kawakamii community in Sanming, Fujian Province.The species diversity, ecological dominance, and edge effect strength of 38 forest gaps with different development stages in different stands of Castanopsis kawakamii community were measured, and Shannon-Wiener index, Simpson index, and index of edge effect strength were calculated.The results showed that the index of the gap edge effect of Castanopsis kawakamii community was about 0.7～1.3 (according to the species diversity index) and 0.3～1.8 (according to the ecological dominance index).The gap edge effect had the trend of increasing the species diversity of forest communities.The index of gap effect was affected by the size and development stage of the gap and the related forest type.The study provided a theoretical basis for the maintenance of species diversity and the forest management in Castanopsis kawakamii community.

Population dynamics of Quercus variabilis on northern slope of Qinling Mountains

ZHANG Wenhui, LU Zhijun, LI Jingxia, LIU Guobin

2003, (9):  1427-1432. 

Asbtract ( 940 )   PDF (541KB) ( 336 )  

Studies on the population dynamics, age structure, spatial distribution pattern, life table, and survival curve of Quercus variabilis showed that the Q.variabilis population on the northern slope of Qinling mountains was increasing.The number of young - aged individuals was larger, and that of middle-aged and old individuals was smaller.The life tables for different age classes showed that the mortality at age classes Iand IIwas the highest, and the mortality rate was decreased with increasing age.However, at age classes VIIand VIII, the mortality rose again for their decrepitude.The expected life span of age classes III, IVand Vwas higher, and decreased gradually with increasing age.The survival curves were the type of Deevey III, and the distribution pattern of population was aggregative as a whole.As the age increased, the intensity of aggregation decreased, and tended to a random distribution at higher elevations.Awise management should accelerate the recovery of Q.variabilis population and the enhancement of its productivity.The altitude 800～1100 m was the favorable habitat for Q.variabilis population.As for the Q.variabilis at lower altitude, its protection should be reinforced, and the disturbance from human beings should be reduced.Forest thinning and other fostering management at middle altitude should be given in time.The target trees at higher altitude should be fostered.

Evaluation on sustainability of forest resources in Bailong River forest region, Gansu Province

GUO Zhenggang, CHENG Guodong, WU Bingli, CHEN Yuqi, SUN Xuegang

2003, (9):  1433-1438. 

Asbtract ( 923 )   PDF (774KB) ( 369 )  

Based on the theories of sustainable development of forest resources, this paper constructed an index system for the integrative evaluation on the sustainability of forest resources in Bailon River forest region of Gansu Province.After calculated the index values of five strategic levels and twenty measure levels, the degree of harmony (DH) was obtained, with which, the sustainability of test forest resources could be evaluated.The DH value was 0.5320 in 1996 and 0.6100 in 2000, which was smaller than the theoretic value of 0.7000, and hence, this forest region belonged to non-sustainable development, but made some progress for its sustainability.

Ecological restoration effects of typical manmade ecosystems and relationships between restoration variables in middle Yunnan area

WANG Zhenhong, DUAN Changqun

2003, (9):  1439-1445. 

Asbtract ( 1090 )   PDF (744KB) ( 354 )  

This paper studied the restoration effects of Pinus yunnanensis forest, mixed Eucalyptus maideni-Acacia meam-sii forest, Eucalyptus maideni forest and restored natural vegetation in middle Yunnan area.The man-made forests consisting of different tree species had different effects on plant diversity, forest hydrology, soil surface erosion control, soil amelioration, and forest characteristics.Afforestation with native species promoted the plant diversity.Recovery Distance Index(RDI) was calculated for the evaluation of the forest restoration extent based on Principal Component Analysis (PCA).The restored natural vegetation P.yunnanensis forest, E.maideni forest, and A. mearnsii-E. maidensi forest would need correspondingly 29.14, 14.36, 34.23, and 11.03 years to recover to the ecological functions of zonal climax community.There were some relationships among forest recovery variables.Shannon-Wiener index, herbage coverage, community evenness, species diversity, soil available K, soil bulk density, biomass of herbage, woody plant coverage, timber volume of woody plant, soil total K, soil erosion, soil Si/V, littersfall, soil non-capillary porosity and through-fall were the main variables among the forest restoration variable dealt with in our work.Diversity played a central role in the restoration of ecosystem structure and functions.

Eco-physiological responses of Picea mongolica ecotypes to drought stress

ZOU Chunjing, HAN Shijie, XUWenduo, LI Daotang

2003, (9):  1446-1450. 

Asbtract ( 986 )   PDF (651KB) ( 430 )  

The seedlings of different Picea mongolica ecotypes were treated with drought stress, and their height growth, MDA, proline, and chlorophyll content were investigated.The results showed that the height growth was obvi-ously reduced by drought stress.With sufficient water supply, the height growth of f.viridis W.D.Xu f.nov Picea mongolica was rapid and obviously better than that of f.purpurea W.D.Xu f.nov Picea mongolica, but was obviously reduced by intense drought stress.Furthermore, drought stress shortened the annual growth period of Picea mongolica, and made its terminal hud formation more than one month earlier, increased in both needles and roots, but was higher in needle than in root.The MDA content was higher in Picea mongolica than in f.viridis W.D.Xu f.nov Piburcea mongolica, and the proline content in needles was increased with increasing drought stress, hut in roots, the proline content was higher in f.viridis W.D.Xu f.nov Picea mongolica than in f.purpurea W.D.Xu f.nov Picea rnongolica and f.rubra W.D.Xu f.nov Picea mongolica.The latter 2 forms showed a similar trend in chlorophyll content.Their chlorophyll a, chlorophyll b and total chlorophyll contents increased at the beginning of drought treatment, and then decreased with increasing drought stress.The chlorophyll content of f.viridis W.D.Xu f.nov Picea mongolica decreased with drought stress.The ratio of chlorophyll a/b decreased from maximum to minimum in f.viridis W.D.Xu f.nov Picea mon-golica,but decreased in a relative small extent in f.purpurea W.D.Xu f.nov.It's proved that f.purpurea W.D.Xu f.nov Picea mongolica had a larger drought-resistance capacity than f.viridis W.D.Xu f.nov, and f.rubra W.D.Xu f.nov was a typical transitional ecotype from f.purpurea W.D.Xu f.nov to f.viridis W.D.Xu f.nov.

Succession pattern of artificial vegetation community and its ecological mechanism in an arid desert region

XU Cailin, LI Zizhen

2003, (9):  1451-1456. 

Asbtract ( 1102 )   PDF (671KB) ( 430 )  

Focusing on the artificial vegetation protection system of the Shapotou section of Baotou-Lanzhou railway in the arid desert region of China, this paper examined the dynamics of dominant plant species and the succession pattern of artificial plant community in the process of establishing and developing regional artificial vegetation.It also studied the driving force and the ecologically intrinsic mechanism of the community succession.The results demonstrated that the species composition of the artificial vegetation dramatically changed after 40 years of succession, from original artificial plant community of shrub and semi-shrub to artificial-natural desert plant community with annual herb dominated.During the process of succession, the importance values of artificial shrubs, such as Caragana korshinskii and Hedysarum scoparius, decreased and gradually retreated from the artificial plant community, while the naturally multiplied annual herb, such as Eragrostis poaeoides, Bassia dasyphylla, Salsola ruthenica, Chloris virgata and etc., were presented one after another and gradually became dominant.Besides, Artemisia ordosica always played a key role in the community due to its ability of naturally sowing and self-replacement.This type of succession pattern was closely related to the shortage of precipitation resource in this region and the formation of soil crust which inhibited the reproduction of shrub and perennial herb with deep root systems.This study provided a theoretical ground for realizing persistent development of artificial plant community.

Soil seed banks of different grassland types of Alashan arid desert region, Inner Mongolia

ZENG Yanjun, WANG Yanrong, NAN Zhibiao, WEI Dong, CHEN Shanke, LI Baoer

2003, (9):  1457-1463. 

Asbtract ( 1193 )   PDF (648KB) ( 341 )  

Investigations on the soil seed banks of different grassland types of Alashan arid desert region in Inner Mongolia showed that when the altitudes of sampling plots increased from 1370 m to 1750 m, the soil seed densities of natural grasslands decreased from 326 grain·m^-2 to 76 grain·m^-2.At the altitude of 1100 m, the soil seed density was 56 grain·m^-2 in typical desert plot, but only 8 grain·m^-2 in the sand dune plot.After the vegetation was restored with Artemisa sphaerocephala on sand dune, its soil seed density increased obviously, almost as 17～29 times as sand dune's.In this study, 31 seeds m^-2 were sampled, which belonged to 11 families.Among them, annual plants accounted for 77%, 100% and 70%, perennial plants accounted for 21%, 0 and 16%, and semi-shrubs accounted for 2%, 0 and 14%, respectively for natural grassland, sand dune and sown grassland.Shrub seeds were not found in all the soil seed bank plots.When the altitudes of sampling plots increased from 1100 m to 1750 m, the species richness (Margalet index) of soil seed banks of natural grasslands increased from 1.49 to 2.77, and the species diversity (Shannon-Winner index) increased from 0.697 to 0.917.

Landscape structure and ecological coupling analysis of ecotone on the west Sonnen Plain

SONG Changchun, DENG Wei, SONG Xinshan

2003, (9):  1464-1468. 

Asbtract ( 1017 )   PDF (512KB) ( 178 )  

Ecotone is a special zone in the landscape, which is very susceptive to the changes in environmental conditions, and hence, is prone to the disturbance by unfavorable conditions.Human activity has a series of positive and negative effects on it, and greatly changes the geo-chemical process in the ecosystem.In the ecosystem, especially in the ecotone, different systems and regimes are interconnected and inter-determined.For the sustainable development of ecosystem and the protection and rational utilization of resources, it is of great importance to study this internal relationship and to seek rational regulation and control measures.With the ecotone in the west Songnen Plain as an example, and based on the studies of the topography, physiognomy, soil, vegetation, and their geographic distribution in the ecotone.,this paper explained the structure of the ecological landscape, and quantitatively analyzed the ecological geo-chemical processes under different landscape conditions.In addition, this paper also tried to make coupling analyses to the ecologic succession and the landscape geo-chemical environment.Under current conditions, the succession of plant communities and the shift of soil landscape geo-chemical conditions in the west Songnen Plain are almost coinstantaneous, and these two factors can inter-determined under certain conditions.

Dynamics of atmospheric6 ¹³C in the past 440 years in Aleitai, Xinjiang

CHEN Tuo, QIN Dahe, LIU Xiao-hong, REN Jiawen, LI Jiangfeng

2003, (9):  1469-1472. 

Asbtract ( 991 )   PDF (460KB) ( 195 )  

Since industrial revolution, a large amount of anthropogenic CO₂ from fossil fuel combustion and deforestation has been emitted into atmosphere, and thus, the atmospheric CO₂ concentration increased rapidly, while the δ¹³C in atmospheric CO₂ became lower and lower due to Suess effect.Therefore, the prediction of δ¹³C is crucial for studying global changes.In order to make an accurate prediction, it is necessary to understand its historical variation.The dynamics of δ¹³C in plants can sensitively reflect it.In this paper, the dynamics of δ¹³C in atmospheric CO₂ in the past 440 years in Aleitai, Xinjiang were reconstructed by using tree-ring δ¹³C series and plant stable carbon isotope fractionation model.The results showed that atmospheric δ¹³C value was relatively constant before 1850 (R²=0.052), which was about -6.60‰, while a sharp decrease in atmospheric δ¹³C with an average of - 7.02‰ was found since 1850 (R²=0.65).Compared with those from ice core bubbles, more fluctuations were found in atmospheric 8 Cderived from tree-ring series, possibly due to the higher resolution of the latter, and the difference of real atmospheric δ¹³C between the growth site of the tree and the globe.

Application of ISSR technology in genetic diversity detection of Jute

QI Jianmin, ZHOU Dongxin, WUWeiren, LIN Lihui, WU Jianmei, FANG Pingping

2003, (9):  1473-1477. 

Asbtract ( 901 )   PDF (704KB) ( 395 )  

The genetic diversity among 27 accessions of Corchorus, including 10 Jute species, was investigated with ISSR technique.283 DNA bands were amplified with 25 ISSR primers, among which, 263 (92.85%) were polymorphic, with 10.48 bands per primer in average.Afurther systemic cluster analysis indicated that the accessions could be clustered into three groups, and the group Ⅱ (including two cultispecies and their close wild species) was obviously genetically different from the groups I and Ⅲ (including eight wild species).Moreover, 16 accessions in group Ⅱ presented a higher intraspecific genetic resemblance, while 11 accessions among groups I & Ⅲ showed an abundant interspecific genetic diversity.After synthesized the relevant findings of morphology and DNA classification, it's found that C.urticifolius could be one of the original wild species, C.tilaculariszic was a variation of C.tilaculari, and Tian Jute could be an untitled wild species.

Interrelationship between water use efficiency and nitrogen use efficiency of different wheat evolution materials

LI Yangyang, ZHANG Suiqi, SHAO Mingan

2003, (9):  1478-1480. 

Asbtract ( 933 )   PDF (326KB) ( 366 )  

Afield micro -plot experiment on the interrelationship between water use efficiency and nitrogen use efficiency of different wheat evolution materials at the whole plant level showed that both water and nitrogen use efficiency increased gradually during the long evolution process from diploid to hexaploid.The water use efficiency was positively related with nitrogen use efficiency across nine evolution materials excluding French S.cereals, suggesting that the high nitrogen use efficiency of French S.cereals might be related with physiological mechanisms other than WUE.

Niches analysis of three aphid populations on spring sowing maize

DING Wei, ZHAO Zhimo, WANG Jinjun, CHEN Guihong

2003, (9):  1481-1484. 

Asbtract ( 953 )   PDF (393KB) ( 413 )  

Systematic analysis of aphid populations and niches patterns on spring sowing maize was carried out during 1998～1999 in the suburbs of Chongqing.The results indicated that there were three aphid populations Rhopalosi-phum maidis Fitch.,Rhopalosiphum padi Linn, and Sitobion avenae Fahricius distributed on the spring sowing maize.The mixed aphid populations traded off during the growth period of spring sowing maize, and two peaks of quantitative counts were shown at the mid and last ten days of May and the last ten days of June.In addition, the niches of aphid population were also discussed from one dimension (i.e., temporal or spatial) to two dimensions (i.e., temporal and spatial).Through the quantitative analysis of niche breadth and niche overlap, the highly temporal differentiation of M.avenae and the highly gathering character of R.maidis were all indicated. R.padi showed an indistinct differentiation, while R.maidi was a dominated population on the spring sowing maize.

Three-dimentional distribution pattern dynamics of Erythroneura sudra and its natural enemy Erigonidum graminicola

ZOU Yunding, ZHOU Xiazhi, BI Shoudong, LI Lei, GAO Caiqiu, DING Chengcheng

2003, (9):  1485-1488. 

Asbtract ( 1075 )   PDF (399KB) ( 173 )  

Investigations on the Erythroneur sudra and Erigonidum graminicola populations in three layers (upper, middle and lower) and four directions (east, south, west and north) of peach tree crown showed that both of them had aggregated spatial distributions in these 7 part, because 5 parameters used to analyze the distribution reached required standard.Each insect was attracted by the others, as the parameter (a) in Iwao formulation m^*= a +Bx-(1971) was positive.The average density of aggregation was the biggest in its middle layer and east direction, and the smallest in its lower layer and south direction .The biggest average density of aggregation appeared in mid-September.

Soil organic carbon pool and its spatial distribution pattern in the Circum Bohai Region

LIU Guohua, FU Bojie, WU Gang, DUAN Guilan

2003, (9):  1489-1493. 

Asbtract ( 950 )   PDF (711KB) ( 413 )  

The research and management of soil carbon pool and the effect of land-use on it are the key project of study on global change.In this paper, the data of 1374 soil profiles in the Circum Bohai Region were used to estimate the soil organic carbon (SOC) pool of this region.The results showed that in this region, the total soil organic carbon pool in1m depth was 2.1 Pg C, and the biggest SOC pool was brown soil, occupying55.6 % of the total SOC.The second one was moisture soil, accounted for 26.9 % .The SOC pools of aeolian sandy soil and dark brown soil were very small, only about 0.1% of the total.However, the soil organic carbon density (OCD) of boggy soil was the biggest (22.90 kg C穖^-2), the second was dark brown soil (16.04 kg C穖²), and the lowest were aeolian sandy soil (2.88 kg C穖^-2) and solonchak (6.0 kg C穖^-2), implying that desertification and salinalization could reduce soil organic carbon.Moreover, the results also suggested that the topsoil held 673.30 Tg C.It meant that there was about one-third of the total SOC could be easy to be disturbed.According to the OCDat its level distribution gradient, it could be divided into four regions, i.e., coastal region, plain region, northwestern region, and hilly region.The order of OCD from high to low was hilly region, northwestern region, plain region, and coastal region.This regulation reflected not only the role of climate and landform, but also the effect of human activity intensification on SOC.Therefore, it was very important to protect and manage the land in this region well for the SOC maintenance and the sustainable land use.

Spatial distribution characteristics and ecological effects of carbon and nitrogen of soil in Huolin River catchment wetland

BAI Junhong, DENG Wei, ZHU Yanming, LUAN Zhaoqing, ZHANG Yuxia

2003, (9):  1494-1498. 

Asbtract ( 1001 )   PDF (721KB) ( 659 )  

This paper studied the spatial distribution characteristics and ecological effects of organic carbon and nitrogen in soils of Huolin River catchment wetland in horizontal and vertical levels.The results showed that the differences of horizontal and vertical distribution of organic carbon and nitrogen were very obvious, and of all the factors such as the period of wetting and drying cycles, leaching, plant and flood etc.,the period of wetting and drying cycles was contents the critical one, which caused the differences.Soil organic carbon was significantly correlated with soil nitrogen (r=0.977).The ratio of carbon and nitrogen (C/N) changed along with the humidity gradient, and soil pH values obviously influenced the concentration of organic carbon and nitrogen.The correlation of C/N values and organic carbon and nitrogen contents in wetland soil and in grassland soil were remarkably different, and the ecological effects mainly included production effect and clarification effect.

Reserves and spatial distribution characteristics of soil organic carbon in Guangdong Province

GAN Haihua, WU Shunhui, FAN Xiudan

2003, (9):  1499-1502. 

Asbtract ( 1214 )   PDF (510KB) ( 463 )  

Soil organic carbon is the main part of terrestrial carbon reservoir and important part of soil fertility.The spatial distribution and reserves of soil organic carbon are very important for studying soil carbon cycle.According to the data from the second soil survey, soil organic carbon reserves was estimated and its spatial distribution was analysed by using GIStechnique.The results showed that the total amount of soil organic carbon is about 17.52×10⁸t.The carbon density of laterite, lateritic red soil and red soil in Guangdong Province is 8.83, 10.31, 9.15 kg·m^-2, respectively;lower than the mean carbon density of China.The carbon density of yellow soil and rice soil is 12.08, 12.17 kg·m^-2, respectively; higher than the mean carbon density of china.Soil carbon density is about 10.44 kg·m^-2 in Guangdong.The spatial distribution characteristic of soil organic carbon density in Guangdong is that the carbon density in south Guangdong Province is higher than that in north Guangdong Province, in that soil organic carbon density in north and middle Guangdong Province is 5～10 kg·m^-2 and in east Guangdong Province is 10～15 kg·m^-2.Soil organic carbon density mostly vary among 5～15 kg·m^-2.

Effect of nitrogen nutrition on endogenous hormone content of maize under soil drought conditions

ZHANG Suiqi, SHAN Lun

2003, (9):  1503-1506. 

Asbtract ( 946 )   PDF (532KB) ( 466 )  

It is realized in recent years that roots play an important role in the control of shoot growth and development, not only because they can continuously provide the shoot with water and nutrients, but also because some chemical messengers are produced in roots to response soil drought stress and transported through transpiration stream to shoot where physiological processes are regulated.Extensive studies showed that the decrease of leaf conductance was closely related to the increase of xylem ABA concentration, suggesting that ABA can act as a water stress signal to regulate the physiological response of shoot.Fertilizer plays an important role in increasing crop yield and water use efficiency (WUE) on dry-land farming.It is not clear, however, whether the application of Nfertilizer can affect the root's signal intensity in drought stress and thus regulate its stomatal responses.Experiment with 3 water levels (35%,55% 和75%± 5% of field capacity) and 2 Nfertilizer levels (high Nand low N) was designed to investigate the effect of soil drought and Nnutrition on endogenous hormone concentration (ABAand ZRs) and stomatal conductivity of maize under potted conditions.The results showed that the application of Nsignificantly increased the stomatal conductivity of maize leaf under both drought and watered conditions.Meanwhile, it markedly decreased the ABAconcentration in root xylem sap, but increased ABA concentration in leaf of maize under soil drought conditions.The application of Ndecreased ZRs concentration in root xylem sap as well, which means that ZRs did not play a role in counteractive to ABA under soil drought conditions.The lower ABAconcentration in root xylem sap of high Nmaize rather than the higher ABA concentration in maize leaf accounted for the higher stomatal conductivity of high Nmaize leaf under soil drought conditions.

Parameters of energy flow in wheat - corn intercropping agroecosystem

WANG Jianlin, WANG Li, BAO Zaide, WANG Yuanlin

2003, (9):  1507-1511. 

Asbtract ( 1050 )   PDF (574KB) ( 349 )  

The parameters of energy flow of primary producers (agricultural crop and weed), consumers (pests and their natural enemies) and decomposer (soil microbe, protozoan and saprozoite) in wheat-corn intercropping agroecosystem in Tibet of China were studied by field investigation and laboratory measurement.The results showed that the wheat-corn intercropping agroecosystem had high primary productivity and energy translation efficiency, and the degression rate of energy flow through food chain was also high.At each nutritive layer of this agroecosystem, relatively less energy was required to product unit energy, and degree of energy utilization of superior nutritive layer from lower nutritive layer was increased gradually.

Effect of plastic film mulching on soil microbial biomass in spring wheat field in semi-arid loess area

SONG Qiuhua, LI Fengmin, LIU Hongsheng, WANG Jun, LI Shiqing

2003, (9):  1512-1516. 

Asbtract ( 955 )   PDF (577KB) ( 350 )  

This paper studied the effect of different periods of plastic film mulching (M₀-no mulching, M₃₀-mulching for 30 days, M₆₀)-mulching for 60 days, and M-mulching for whole growth period) on soil microbial biomass carbon (SMBC) of spring wheat field in semi-arid loess plateau.The mean SMBC in 1999 and 2000 was 335.3 and 259.3 mg·kg^-1 dry soil, respectively.It was 29.3% higher in 1999 than in 2000.The highest SMBC was recorded at the harvest stage in Mtreatment for the two years.In1999, a wet year with more rainfall, the SMBC of M₆₀ and Mtreatments was significantly higher than those of M₀ and M₃₀ in the mid-period of growth, reached its top at the end of the growth period.The highest grain yield was also achieved in M₆₀.It was a dry year in2000, but rainfall was rich in the latter growth period of spring wheat.SMBC increased at the beginning period of growth, and did not increase during the mid-growth period.It increased again during the latter period of growth, and showed a significant difference among the treatments.At the harvest stage of 2000, SMBC in M₀ was the highest among all the treatments.It was similar between Mand M₆₀, and lower than that of M₃₀.In the two years, the ratio of C/N ranged between 7.732～9.042, being lower than the threshold of 11.3, and the ratio of C/P was 300.8～719.6, being higher than the threshold of 300.The two parameters showed that the increase of SMBC was inhibited because of the competition of soil available nutrients between soil microbes and crops.These indicated that soil organic matter content was so shortage that it became the key factor to restrict crop productivity.Under this condition, increasing crop productivity through the input of chemical fertilizers would conceal the problem of soil degradation, and result in a further decrease of soil quality.Along term plastic film mulching would make the problem more serious.

Effect of Sinorhizobium fredii YC4 symbiotic plasmid amplification on nod factors and symbiotic N-fixation

MIAO Lihong, ZHOU Junchu

2003, (9):  1517-1520. 

Asbtract ( 1158 )   PDF (539KB) ( 246 )  

Sinorhizobium fredii YC4 can form nitrogen-fixing nodules on soybean (Glycine max) and wild soybean (G.soja).It can produce unique lipochitooligosaccharide nod factors (LCOs), in comparison with the other four strains of S.fredii.The constitution of LCOs produced by YC4 contained more hydrophobic substitutions detected by Thin-layer chromatography (TLC) of ¹⁴C-labeled nod factors.Aspontaneous mutant termed YSC3 amplified in the symbiotic plasmid was isolated from YC4, which can produce more amount of LCOs than its parental strain at 28 ℃,and showed a difference in the construction of LCOs.Nodulation test indicated that YSC3 only formed ineffective nodules on soybean G.soja.

Identification on an antagonistic rhizobacterium X3 from rhizosphere of cucumber

SHEN Aihua, ZHANG Bingxin, LI Bin, SHEN Lirong, YU Jingquan

2003, (9):  1521-1524. 

Asbtract ( 938 )   PDF (303KB) ( 448 )  

Classical physiological and biochemical methods, Biolog, and 16SrDNAanalysis were used to identify the strain X3 which could control cucumber seedling damping-off.Physiological and biochemical identification showed that it belonged to Pseudomonas aeruginosa, but Biolog identification showed it was P.spinosa.16SrDNA determination and analysis was used for further identification, which showed that the 16SrDNA sequence of X3 shared 93.7% homologies with published sequence of P.aeruginosa from GenBank, and both sequences constituted a branch in Phylogenetic tree.Based on these results, it is considered that the strain X3 belongs to one strain of P.aeruginosa.

Effect of environmental factors on the growth and fatty acid composition of five endophytic fungi from Sapium sebiferum

DAI Chuanchao, YU Boyang, XU Zenglai, YUAN Sheng

2003, (9):  1525-1528. 

Asbtract ( 1182 )   PDF (461KB) ( 220 )  

Five fungi species including Rhizoctonia sp.,Sclerotium sp., Acremoniell sp., Chaetomium sp.and Pestalo-tiopsis sp.screened from the inner bark of Sapium sebiferum (Level) Roxb.were used to study their growth under different environmental factors, with the biomass and fatty acid composition as main indexes to elucidate the relationship between plant and its endophytic fungi.Compared with that from synthesized medium, a higher biomass was harvested when the fungi were cultured on liquid potato dextrose medium; the unsaturation index of fatty acid (IUFA) was lower, and the main fatty acids in the fungi were linoleic acid, palmitic acid and oleic acid.Compared with the fungi grown on the synthesized medium without Sapium sebiferum' s extract, the Sclerotium sp.growth was promoted, and the others were inhibited when the extract was added to the synthesized medium.At the same time, the IUFA were increased.When0～1.0 mol·L^-1 NaCl was added in Sclerotium sp.'s culture medium, the biomass was not changed notably; IUFA in 0～0.5 mol·L^-1 NaCl was not significantly different, while in the range of 0.6～1.0 mol·L^-1 NaCl, the IUFA was decreased with increasing concentration of NaCl.It indicated that fungus had a stronger tolerance to salt.Sclerotium sp.'s growth was promoted, and the IUFA was increased when plant oil was added in the synthesized medium.The biomass was the highest by adding1.5% plant oil.The results mentioned above were some way related to the symbiotic relations between the endophytic fungi and their host plant.

Effect of enhanced ammonium nutrition on photosynthesis and nitrate reductase and glutamine synthetase activities of winter wheat

DAI Tingbo, CAO Weixing, SUN Chuanfan, JIANG Dong, JING Qi

2003, (9):  1529-1532. 

Asbtract ( 939 )   PDF (437KB) ( 236 )  

Acontrolled hydroponics experiment was conducted to investigate the effects of three NH₄⁺/NO₃^- ratios (0/100, 50/50 and 100/0) on the photosynthesis and the key nitrogen metabolism enzymes of three wheat cultivars with different sensitivity to enhanced ammonium nutrition (EAN).Compared with NO₃^- alone, EANsignificantly increased the leaf chlorophyll content, net photosynthetic rate, and soluble sugar content.It also significantly increased the soluble protein content in leaves and roots and the nitrate reductase activity in leaves, but had no significant effect on Glutamine synthetase (GS) activity.EANincreased the soluble sugar content in leaves, and correspondingly, enhanced the net photosynthetic rate and maintained a higher soluble sugar/protein in leaves and roots, which was favorable to the nitrogen assimilation and plant growth.

Optimum soil water supply range of Malus pumila

WANG Keqin

2003, (9):  1533-1537. 

Asbtract ( 769 )   PDF (660KB) ( 356 )  

By means of the determination of net photosynthetic rate and transpiration rate of the leaves of seven-year field and two-year spotted Malus pumila(Goldspur) under different soil water contents and illumination and calculation of water use efficiency (WUE), the optimum soil water supply range of Malus pumila was determined.The results showed that: because photosynthetic advantageous radiation (PAR) and soil water content (SWC) decided the value of photosynthetic rate and transpiration rate of Goldspur, thus they influenced the value of WUE.The response of WUE to illumination had relations with soil water.When SWC was 10% (50% of field capacity-FC) or so, the maximum of WUE was the highest value among all the soil water treatment and reached about 230 umol CO₂·g^-1 H₂O.When the water supply was adequate (SWC>15% ), the maximum was only 160 umol CO₂·g^-1H₂O or so, the difference between each SWC level was not obvious and simulated curve fundamentally overlapped, although WUE decreased slowly after reached the maximum.The variation of WUE with SWC had relations with illumination.WUE was the highest while PAR was in the range of 500～1 000 umol.m^-2.s^-1).Because the state of soil water decided the values of stomatic resistance (RS) and leaf water potential, RS and Ψ₁ also had influence on the changes of WUE.When RS and Ψ₁ were respectively 2.0 s·cm^-1 and -3.0 MPa, WUE was the highest, but Pn was relatively low, which was not good to the normal growth and fruitage of trees.From the overall consideration of WUE, Pn and Tr, the scopes of RS and Ψ₁ were 2～6 s·cm^-1 and -2.1～-1.65 MPa, respectively, which not only guaranteed the normal photosynthesis of Goldspur, but also benefited the increase of WUE.The scope of the corresponding SWC was 11%～15%,which was equal to 55%～75 % of FC and this scope could be used as theoretical index of field water supply for Goldspur.

Reproductive biology of Macrobrachium nipponensis in Lake Wuhu

HE Xugang, GONG Shiyuan, ZHANG Xunpu, LIU Jun, HU Qiuyuan, WANG Honghui, TAO Renyong

2003, (9):  1538-1542. 

Asbtract ( 1077 )   PDF (489KB) ( 291 )  

Macrobrachium nipponensis is a key species of freshwater shrimps in China.To know its reproductive biology is very important for its protection and rational use.Studies from September 1998 to September 1999 in Lake Wuhu showed that the spawning ground of M.nipponensis was situated in the littoral zone of the whole lake.The main spawning period of overwintering shrimps was from mid-April to mid-July (water temperature 20.5～31℃), and that of non-overwintering shrimps was from mid-July to mid-September (water temperature 31～23℃).The sex ratio(♀:♂)increased gradually during the spawning period, and the absolute fecundity of overwintering shrimps was higher than that of non-overwintering ones.The relationship between absolute fecundity and body length and between absolute fecundity and body weight could be expressed as cubic equation and simple linear equation, respectively.The relative fecundity (R_w) of M.nipponnensis could regard as a constant, and its 95% confidence limits was 1067.76±16.94 eggs·g^-1.

Dynamics of dry deposition velocities (V_d) of atmospheric SO₂ on rapeseed/rice rotation systems in selected area of South China

HU Zhengyi, XU Chengkai, CAO Zhihong, WANG Tijian, ZHAO Yanwen

2003, (9):  1543-1546. 

Asbtract ( 924 )   PDF (559KB) ( 298 )  

With the profile meteorological data collected from the farmland micro-meteorological experimental substation, Experiment Station of Red Earth Ecology, Yingtan, Jiangxi, Chinese Academy of Sciences during rapeseed/rice rotation from Nov.1998 to Oct.1999, the surface layer turbulence characteristic parameters (u^*,θ^*,L) and the atmospheric SO₂ dry deposition velocities (V_d) were calculated.The results indicated that the hourly mean V_d of SO₂ dry deposition was ranged from 0.124 to 0.897 cm·s^-1 (mean±SE = 0.507±0.167 cm·s^-1), and its regular dynamic pattern was as follows: it was always higher at daytime than at night, and the mean V_d of SO₂ dry deposition during March-August(0.611 cm·s^-1) was obviously greater than that during Sept.- Dec.and Jan.-Feb.(0.401 cm·s^-1).The mean V_d of SO₂ dry deposition during various crop growth stages was decreased as the order of rice (0.605±0.093 cm·s^-1) > rapeseed (0.491±0.166 cm·s^-1) > follow (0.342±0.174 cm·s^-1).

Effects of simulated acid rains on Cd, Cu and Zn release and their form transformation in polluted soils

GUO Zhaohui, HUANG Changyong, LIAO Bohan

2003, (9):  1547-1550. 

Asbtract ( 1049 )   PDF (446KB) ( 347 )  

The release and form transformation of Cd, Cu, and Zn in polluted red soil and yellow red soil affected by simulated acid rains were studied through batch equilibrium experiments.The results showed that the release of test heavy metals increased significantly with decreasing pHvalue of simulated acid rain.Their release amount was negatively correlated to the pHvalue of acid rains.In polluted red soil and yellow red soil, Cd existed mainly in exchangeable form, and Cu in organically bound and Mn oxide-occluded forms.Zn existed mainly in residual and exchangeable forms in polluted red soil, and in residual and organically bound forms in polluted yellow red soil.To some extents, the release of Cd, Cu and Zn and the chemical forms of Cd and Zn in test soils were affected by soil organic matter content and CEC.The release amount of bio-available Cd and Cu in polluted red soil and yellow red soil was increased greatly with the increasing acidity of simulated acid rains, but the transformation of Zn from stable to bio-available form was not obvious.

Several problems in ecological security assessment research

WANG Genxu, CHENG Guodong, QIAN Ju

2003, (9):  1551-1556. 

Asbtract ( 1098 )   PDF (690KB) ( 408 )  

Ecological security assessment is the identification and judgment of ecosystem completeness and sustainable ability to maintain ecosystem health under all kinds of risks, the core contents of which are ecological risk assessment and ecological health assessment.Ecological risk identification and ecological vulnerability are the composing elements of ecological risk assessment, while ecological health includes three aspects, i.e., ecological completeness, ecosystem vigor, and ecosystem resilience.In the studies of ecological security assessment, the rational combination of ecological risk and ecological health, and the establishment of integrated measure index system based on confirming spatial scale are needed.At present, risk factor identification index, exposure analysis index, and influence (response) analysis index are the broader construction systems of ecological risk index.Nevertheless, on the basis of the classification of EDI, REI and IRI, the method of superimposing exposure analysis index may be the development direction of establishing index system in the future.Among the methods of quantificational assessment, exposure-response analysis was one of the most extensive method used at present, but ecological model method to assess different-scale ecological security will be the main development field, and focused on the security of ecological processes in the future.Ecological security assessment must be intergraded with ecological prediction, security guarantee and management.

Application of mist net in studies of forest bird communities

ZOU Fasheng, CHEN Guizhu

2003, (9):  1557-1560. 

Asbtract ( 1065 )   PDF (468KB) ( 219 )  

It had been more than twenty years for using mist net to study forest avian community.Mist net was very useful for studying cryptic, less vocal or non-vocal, and non-territorial birds, particularly understory birds in forest.The accuracy of mist net was relatively independent of observer biases and skills.It allowed identical and simultaneous sampling of numerous sites and straightforward comparisons among studies done at different sites by different people.So, a lot of ornithologists considered it as a necessary way for studying forest bird communities.Few studies had been reported on bird communities by using mist nets in China.In this paper, some examples on studying forest bird community by using mist nets were introduced, and studies on forest bird community with mist net should be used widely in China in the future.

Ecological protection of medicinal woody plants

YAN Xiufeng

2003, (9):  1561-1564. 

Asbtract ( 1286 )   PDF (472KB) ( 263 )  

Medicinal woody plants, especially medicinal tall trees, play a same important role in forest structure, ecological balance and timber production as other tree species in forest, and due to their additional medicinal values overuse of these trees is more intensive than others.Many medicinal materials are destructively obtained from plants such as roots or bark used as medicinal materials.The contradiction between the utilization and protection of medicinal woody plants becomes more and more incisive.In the present paper, based on the analysis of the utilized situation and specialty of medicinal woody plants, the trouble between the plants protection and utilization was observed, the method to solve it and the fundamental research work needs to be developed were discussed.The following aspects of researches were suggested to be conducted: (a) study on the distribution in organs, seasonal and age variations, and correlation with environmental factors of principal medicinal compositions in mature trees to clear the optimum of harvest and cultivation conditions; (b) study on the distribution in organs, seasonal and age variations, and correlation with environmental factors of principal medicinal compositions in saplings, especially the time course of the variation in medicinal compositions and biomass to achieve the optimal tree ages for the balance between biomass and production of medicinal products during saplings development; (c) study on the influence and regulation of environmental factors on medicinal compounds production in woody plants to look for the optimal cultivated conditions for optimizing the accumulation of biomass and medicinal chemicals; (d) further study on the regulatory mechanism of the induced production of main medicinal compositions by ecological factors at protein (key enzyme) and gene level to accumulate fundamental data for the enhancement of quality and quantity, and approach of new accesses to medicinal products using biological technology (cell culture and gene technology) .Aimed at medicinal woody plants in Chinese forest resources, to develop the fundamental researches on resources protection and rational utilization will create many profound scientific significances.Firstly, medicinal woody plants are the important components of Chinese natural forest resources, so the problem for their protection and utilization, especially for that of tall trees, is quite remarkable and special.To reveal the internal contradictory between plant resources protection and its reasonable exploitation and exploit a practicable access to solve it will promote and accelerate the fulfillment of "natural forest protection project" in China.Secondly, traditional Chinese medicine is a main part of Chinese excellent ancestral culture, and the traditional utilizing models have been carried on for thousands of years.Accompanying with the development of human society, many unavoidable troubles such as the shortage of natural resources and the pollution of natural environment are more and more severely, which make the old models of the traditional Chinese medicine become more and more harmful and inaccessible to mankind.New substitutive approach to the utilization of traditional Chinese medicine, especially to that of Chinese medicinal woody plants will be one of the key methods to improve the present situation.Thirdly, traditional Chinese medicine, the cherish treasure of Chinese ancestral culture, need not only be preserved but also be developed.One of the main problems to restrict the extensive spread of the traditional Chinese medicine is its unstable quality, so to reach the stable quality and good quality is tightly linked to the improvement of traditional Chinese medicine.Hence the environmental regulation to the cultivation of medicinal plants, which can prove and guarantee the stable and high quality, will fit the demand on the production of medicinal plant material, and correspond to the goal of great efficacy and superior quality during the course of modernization of traditional Chinese medicine.

Mycorrhizal diversity and its significance in plant growth and development

SHI Zhaoyong, CHEN Yinglong, LIU Runjin

2003, (9):  1565-1568. 

Asbtract ( 1011 )   PDF (504KB) ( 483 )  

Mycorrhizal diversity, including morphological, species and functional diversity, is an integrative component of biodiversities.Many experiments showed that mycorrhizal diversity played an important role in the origin, evolution, distribution, survival, growth and development of plants.But, mycorrhizal diversity is dependent on plant diversity.It was suggested that mycorrhizal and plant diversities stimulated or retarded each other.The significance of mycorrhizal diversity in plant diversity was also discussed.

Spatio temporal problems of geographic information system in marine fishery

SU Fenzhen, ZHOU Chenghu, DU Yunyan, ZHANG Tianyu, SHAO Quanqin

2003, (9):  1569-1572. 

Asbtract ( 1132 )   PDF (514KB) ( 228 )  

In marine fisheries, it is very important to understand and grasp the spatio-temporal nature.Geographical Information System (GIS) has been applied to describe or forecast the dynamic trend of resources or to set up evaluation model, which is one of high technologies in modern marine fisheries.Based on the review of the development of marine fishery GIS (MFGIS), four spatio-temporal problems it occurred were discussed, and the possible resolutions were prospected.

Several research hotspots in river ecology

CAI Qinghua, TANG Tao, LIU Jiankang

2003, (9):  1573-1577. 

Asbtract ( 1953 )   PDF (686KB) ( 893 )  

River ecology is a vital field in limnological research, and several new theories and methods have been developed and used in the study of lotic systems.In this article, a summary of these new theories was introduced, which includes river continuum concept, ecological water consumption of river ecosystem, services and health of river e-cosystem, ecosystem management, and watershed ecology.The authors suggested that the research of river ecology should be carried out on the scale of watershed, and that the combination of ecosystem health and ecosystem services could be the key point in the sustainable development management of river ecosystem.Seeing that there are few studies in this area in China, relevant research should be conducted as soon as possible.

Ecological studies on genetically engineered microorganism in environment

JIN Suying, ZHANG Jiazhi, DI Junyan

2003, (9):  1578-1580. 

Asbtract ( 967 )   PDF (521KB) ( 321 )  

This paper discussed the main problems which should be considered on the environmental release of genetically engineered microorganism (GEM), including GEM construction, gene transfer, fitness, diffusion, translocation, potential eco-influence and so on.Moreover, aiming at the special ecological characteristic and eco-influence of GEM, this paper brought forward the policy of "respective analysis on different problems", and postulated the corresponding projects of GEM ecological research to apply GEM safely and effectively in nature.

Toxic effects of Cd²⁺ pollution on the biochemical and physiological characters and ultrastructure of Alternanthera philoxeroides

ZHOU Hongwei, SHI Guoxin, DU Kaihe, XU Qinsong, XU Nan

2003, (9):  1581-1584. 

Asbtract ( 865 )   PDF (646KB) ( 368 )  

By imitating different concentration Cd²⁺ polluted water environment, this paper dealt with the changes of some biochemical and physiological characters and the damage of ultrastructure in leaves of Altemanthera philoxe-roides.The result showed that SOD and POD activity first increased in the low concentration pollution and then decreased with the concentration of pollution raised.The content of chlorophyll, chlorophyll a/b value, CATactivity and the content of soluble protein all declined continually.With the concentration of pollution increased, the ultrastructure of cell nuclei, chloroplast and mitochondria became deformed, the permutation of structure inside disordered, swelled, membrane disrupted and vesiculated.The changes of some biochemical and physiological characters accorded with the damage of cell ultrastructure.

Effect of bacterivorous nematodes on bacteria population under gnotobiotic culture

CHEN Xiaoyun, HU Feng, LI Huixin, MAO Xiaofang

2003, (9):  1585-1587. 

Asbtract ( 901 )   PDF (308KB) ( 303 )  

Agnotobiotic microcosm experiment was conducted to study the influence of bacterivorous nematodes (Protorhab-ditis sp.) on bacteria (Pseudomonas fluorescens) population under different conditions including substrate concentration, oscillation pattern, and numbers of nematodes inoculated.When the bacteria were incubated under intermittent oscillation by hand (6 times at 0.5 h intervals, 22℃), their growth was stimulated in the presence of nematodes, and the bacteria grew faster with the increase of nematode numbers and substrate (liquid potato-sucrose medium) concentration.However, when the incubation was under continuous oscillation (100 rpm, 22℃), bacteria population was deflated with the addition of nematodes, and the inhibition was greater when a higher concentration of substrate was used.It was found that the stimulation or inhibition of bacteria population by nematodes occurred in the logarithmic stage of bacteria growth.The optimal and over-grazing of nematodes on regulating bacteria population was discussed.

Acute lethal and behavioral response of Liposcelis bostrychophila (Psocoptera: Liposcelididae) to DDVP

DING Wei, WANG Jinjun, ZHAO Zhimo, LI Xiaozhen

2003, (9):  1588-1590. 

Asbtract ( 909 )   PDF (491KB) ( 208 )  

Book louse Liposcelis bostrychophila is a minor pest in stored products, and may seriously infest the stored products when its population outbreaks.This study was conducted to evaluate the toxic effect of DDVP on various development stages of L.bostrychophila.The results showed that at 28±0.5℃ and 24 h exposure under 75 %～80% RH, the LC₅₀ of the eggs, larvae of 1st to 4th stadium, and adults was 16.83, 0.22, 0.22, 0.23, 0.26 and 0.25 μg·L^-1, respectively.The lethal effect of DDVP on the adults at different exposure periods showed that their mortality was linearly related to the treated time, implying that the test colony of L.bostrychophila was susceptible to DDVP.In the practical fumigation, DDVP as a fumigant had a good effect on the pest control if the development stage, time and periods of treatment were appropriate.