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Table of Content

    25 March 2001, Volume 12 Issue 2
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    Grey correlation and cluster analysis on relationship between Cercidiphyllum japonicum community and its environment
    PAN Kaiwen, LIU Zhaoguang
    2001, (2):  161-167. 
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    The relationship between 10 years old C. japonicum plantation forest community and its environmental conditions was studied by grey correlation method and cluster analysis.The reuslts showed that there existed closer relations among soil organic matter,available Ca,Fe,Mg and N.Except for N and Mn,all soil available elements tested had no direct impact on the absorption and accumulation of corresponding elements by the community.The tree species in different habitats was found to absorb soil elements selectively to some extent.The factors affecting the basal diameter,DBH,height and biomass of C.japonicum could be lined as soil chemical characteristics>soil physical properties>climate factors,in which,available P had little impact on the growth of C.japonicum .It is suggested that C.japonicum could be restored in the area with higher air moisture and with fertile porous soil between elevation of 2200～2700m.
    Articles
    Interspecific association of dominant species in Betula luminiferanatural forest communities of Shaowu, Fujian Province
    LI Jianmin, XIE Fang, CHEN Cunji, ZHANG Siyu, XIAO Rihong
    2001, 12(2):  168-170. 
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    x2test with 2×2 contingency table and Jaccard indices shows that the interspecific association of 16 dominant species in Betula luminifera communities of Shaowu, Fujian Province was of little significant level with few exceptions. The relationships between B.luminifera and Phyllostachys pubescens ,and B. luminifera and Alniphyllum fortunei were significantly positive,showing that there was a high association degree between B.luminifera and Schima superba, B.luminifera, and Castanea henrgi, and B.luminifera and Pinus massoniana based on Jaccard indices.
    Growth analysis on the competition-density effect in Cunninghamia lanceolata stands
    XUE Li, HAGIHARA Akio
    2001, (2):  171-174. 
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    The competition density (C D) effect in Cunninghamia lanceolata stands was analyzed by using the reciprocal equation 1/ w=Aρ+B, where w and ρ represent mean stem volume and density,respectively,the C D curve given by the reciprocal equation on logarithmic coordinates shifted upward with time.With the increase of physical time t the biological time τ defined as the integral of λ(t) ,the growth coefficient in general logistic growth curve,tended to increase to the maximum.The coefficients A and B included in the reciprocal equation were calculated at each growth stage. With increasing τ, the coefficient A increased abruptly up to a maximum value,and then tended to decrease gradually to a constant level, whereas the coefficient B decreased exponentially,and tended to close to zero. The coefficient of growth λ(t) decreased with increasing stand age.
    Physiological and growth responses of Sabina vulgaris to disturbance of leaf removal
    HE Weiming
    2001, (2):  175-178. 
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    To examine the physiological and growth responses of Sabina vulgaris to natural disturbance, a field experiment to simulate the grazing and pest disturbance was conducted in Maowusu sandy land through artificially removing leaves.The disturbance of leaf removal could modify the species’ diurnal physiological dynamics through changing the timing of extreme values,and moreover,change the average daily values of physiological indexes significantly.Leaf removal could affect the growth traits,but not biomass allocation significantly.The consequences of the distrubance were confined by its means and intensity,and there existed significant differences in sensitivity of different physiological and growth characteristics e.g.,net photosynthesis rate and transpiration rate to leaf removal.The disturbance of leaf removal,especially that of old leaf removal,had compensation effects.Therefore,moderately removing the leaves on the shoots with less than 2 years old could enhance the growth and the biomass accumulation of curent-year shoots.
    Characteristic analysis on different thermal active surfaces in canopy gap of tropical secondary forest
    ZHANG Yiping, WANG Jinxin, MA Youxin, LIU Yuhong
    2001, (2):  179-184. 
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    Microclimatic measurements were conducted in the canopy gap of tropical secondary forest in Xishuangbanna in fog-cool and dry-hot season.The daytime thermal effect of different thermal active surface in the canopy gap was discussed,and the variations of trunk surface temperature near gap edge and of surface temperature on the gap were analyzed.The result shows that the woody-wall surface is new thermal active surface on the vicinage of canopy gap,with the exception of the forest canopy surface, soil surface in the forest gap,and soil surface of the interior. Because of the influence of season,situs and time,the thermal effect of different thermal active surface of gap was significant different. Being subject to fog, the soil surface on the center of canopy gap is an important thermal active surface in the morning;while in the midday and afternoon,because of the influence of incident radiation, the woody wall and soil surface of edge on the east and the woody wall surface of edge on the north are the key thermal active surface of the canopy gap. In the midday,the thermal active was salient on the surface of gap,and in the afternoon,it was salient on the woody wall. The thermal variations of canopy gap of forest are controlled by the thermal characteristics of different thermal active surfaces and by their interaction,affecting the growth of plants.
    Relationship between water supply and consumption of main planting tree species of protection forests in loess area of western Shanxi Province
    WEI Tianxing, YU Xinxiao, ZHU Jinzhao, WU Bin
    2001, (2):  185-189. 
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    Based on three years point-fixed observation,this paper analyzed the relationship between water supply and consumption of black locust(Robinia pseudoscacia L.)and Chinese pine(Pinus tabulaeformis Carr.),the main tree species of protection forests in the loess area of the western Shanxi Province.In April,May and June,the water supply was less than water consumption,while in raining season,the water supply was abundant,and the water storage in soil was increased. During dry seasons and years, more water consumption and less available water supply occurred in high-density stand,showing a serious water deficiency. The water deficiency was in order of south-facing slope>semi-south-facing slope>north-facing slope.The study shows that water consumption characters coefficient could be used as an index to indicate the growth pattern of trees,and the relationship between water supply and consumption.
    Landscape structure and greenland spatial pattern in workshop district of Wuhan Iron and Steel Company
    ZHOU Zhixiang, SHAO Tianyi, ZHOU Xiaoqing, HE Jicheng
    2001, (2):  190-194. 
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    The landscape structure and greenland spatial pattern in the workshop district of Wuhan Iron and Steel Company were investigated and analyzed on the basis of landscape ecological theory. The results showed that the main parts of the landscape structure were the artificial landscape elements such as building and concrete covering patches, highway and railway bed corridors, and industrial reservations. All of these artificial landscape elements accounted for 74.37% of patch area and 57.70% of patch dominance. In the landscape, the building and concrete covering land had the maximum percentage of patch area (56.43%) and the maximum dominance (35.59%).The special purpose greenlands had the highest fragmentation index (5.0591 ind穐m-2) and the wide-ranging distribution. The corridor density (13.78 km穔m-2) was high, and the highway had more effects on landscape than the railway.All the results reflected not only the essential landscape features of industrial region,but also the rational trend of landscape structure in the workshop district of Wuhan Iron and Steel Company. In the greenland, the road greenbelts had the maximum patch number, area percentage (66.07%), and dominance (75.31%), the shelter forests being mainly composed of tree species had high patch average area (8454.45m2) and environmental benefit, and the ornamental greenlands had abundant plant species and varied scenery. The greenland system was initially formed by four afforestation districts,using shelter forests and ornamental greenlands in large patch as a center connected by road greenbelts. It should be attached importance to the relatively high dominance of wild grasslands, the low area percentage of shelter forests and the imperfect road greenbelts to develop the uncovered lands and to improve the quality of the greenland system.
    Articles
    Evaluation on comprehensive benefits of different regulation models of agroforestry ecosystem in snail river beach
    SUN Qixiang, WU Zemin, WEI Chaoling, PENG Zhenhua
    2001, 12(2):  195-198. 
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    The economic,ecological,social and comprehensive benefits of different regulation models of agroforestry ecosystem in Nangeng river beach were evaluated by AHP.The resuls showed that agroforestry ecosystem was significantly superior to reed(Phragmites communis)system.Different regulation models of agroforestry ecosystem had different benefits.The sheet-thinning model had the highest economic,social,and comprehensive benefits,and it was the optimal regulation model.For all thinning models,the key approach to further raise benefits was to choose some intercrop variations,which had a high economic value,especially a high ratio of output to input.For no-thinning model,keeping on intercropping was the effective measure to raise the social and comprehensive benefits.
    Relationship between atmospheric temperature and growth characteristics of main edible grapes in South China
    DING Zhien, WEI Chaoling
    2001, 12(2):  199-204. 
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    The study shows that there existed a significant relationship between the new branch growth of grapes and temperature, especially effective accumulate temperature. Kyoho had the fastest new branch growth rate among all varieties,which was 0.43433cm in length with raising 10℃ while effective accumulate temperature was over 190.68℃. Mixiangbao had the slowest new branch growth rate,which was 0.17150cm in length with raising 10℃ while effective accumulate temperature was over 367.19℃.The economic properties and quality in variety character were researched by fuzzy valuation. The results showed that Kyoho, Jingya, Fujiminori, Mixiangbao, and Longbao were worthy of spreading,while Zizhenxiang would be limited in production,and Wase takasumi and Heifeng should be eliminated through selection.
    Effect of plastic film mulching on crop yield and nitrogen efficiency in semiarid areas
    LI Shiqing, LI Fengmin, SONG Qiuhua, WANG Jun
    2001, 12(2):  205-209. 
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    The effect of plastic film mulching,water storage in soil profile before sowing,and nitrogen fertilization on crop yield and nitrogen efficiency was examined in this paper.The study site was on the cultivated lossial soil in semiarid areas with 415mm of annual rainfall and the test crop was spring wheat,Triticum aestivum.In order to study the effect of plastic film mulching,4 levels of mulching were designed,including mulching of 0,30 and 60 days after sowing and mulching over the whole growing period.The results showed that increase of soil water storage,plastic film mulching and nitrogen fertilization increased crop yield significantly(α<0.01),and their effect followed in the order of nitrogen fertilization>increase of water storage>plastic film mulching.The effect of mulching on crop yield varied with water storage,nitrogen fertilization and mulching periods.When the water storage was low,there was no significant difference in crop yield between mulching and no mulching,although mulching increased crop yield slightly,and the nitrogen efficiency was higher for no mulching and mulching 30 days.When the water storage was high,the difference between the yield of muching 60 days and no mulching was significant,but no difference in nitrogen efficiency was found for mulching 30 days,60 days and over whole growing period.It was suggested that mulching over whole growing period was of less significance in practice.
    State of soil available sulphur and its requirement along Huaihe River region
    YU Zhongxiang, ZHANG Chenglin, WANG Shijia
    2001, 12(2):  210-212. 
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    This paper investigated the available S contents of yellow cinnamon soil,fluvisol,shajiang black soil and paddy soil,which were developed from loessial ancient-river alluyium,recent loess-flooding deposit,and Xiashu loess.The input and output,and the abundance and deficiency of soil available S were studied in combination with the mode of land utilization and fertilization,and the soil demands of S was predicted.The results showed that the content of soil available S was decreased in the order of paddy soil>shajiang black soil>yellow cinnamon soil>fluvisol,and there was more S in irrigated land than in dry field in case of different land utilization.From the viewpoint of parent material,the deficiency frequency of soil available S was in the order of loessial ancient-river alluvium>Xiashu loess>recent loess-flooding deposit,and the potential deficiency frequency of S was loessial ancient-river alluvium>recent loess-flooding>Xiashu loess.As for soil type,the deficiency frequency of soil available S was in the order of deposit shajiang black soil>yellow cinnamon soil>fluvisol>paddy soil,and the potential deficiency frequency of S was paddy soil>fluvisol>shajiang black soil>yellow cinnamon soil.Shajiang black soil had the largest area of lacking available S,which amounted to 7.0×104hm2,yellow cinnamon soil had an area of 2.0×104hm2,and fluvisol was 6000hm2.The total area of lacking S was 9.6×104hm2,accounted for 25.06% of total cultivated area.The total area of potentially lacking S was 1.6×105hm2,accounted for 42.04% of the total.According to the current available S content in soils and the S demands for high yielding crops,the S demands of 3.8×105hm2 farmland in three counties and one district of Bengbu was about 3.0 ×106kg and 1.2×106kg in the recent and far future,respectively.
    Effect of NPK and B supply levels on boron uptake and biological properties of different genotypic oilseed rape
    LOU Yunsheng, YANG Yuai
    2001, (2):  213-217. 
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    Pot experiment was conducted to study the boron absorption by oilseed rape(Brassica napus),the mechanism of its resistance to boron deficiency,and the effect of boron deficiency on its biological properties under different NPK supply levels.The results indicated that under boron deficiency,increasing NPK supply aggravated boron deficiency symptoms,which led to the decrease of leaf area and its growth rate and nitrate reductase activity(NRA) and the increase of chlorophyll(a+b) content at seedling stage,and the decrease of the number of productive branches and pods of each plant and seed yield at maturity.It was suggested that the ratio of boron concentration in youngest open leaves(YOL)to youngest mature leaves(YML) at seedling stage could be an index to judge the boron mobility in plants of different genotypic oilseed rape.Boron mobility and its utilization efficiency were one of the important nutritional mechanisms responsible for the difference in response of different genotypic oilseed rapes to boron deficiency.
    Effects of different varieties and sowing dates on development stages of wheat
    LI Cundong, CAO Weixing, DAI Tingbo, YAN Meichun
    2001, 12(2):  218-222. 
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    The effects of different sowing dates and varieties on development stages of wheat were studied in this paper.The results showed that the emergence of tiller was mainly regulated by the ecological factors rather than the genetic effect.For winter-type variety(Jing 411),most variable growth duration throughout the entire growth cycle occurred from tillering to jointing. In contrast,the timing of single ridge stage was determined by genotypic effect rather than ecological factors.Single ridge to double ridge stage was most sensitive to vernalization progress.For spring sowing of winter-type variety,the vernalization process could last till floral primordium differentiation stage. The corresponding relationships existed between phenological and spike development stages in different sowing dates,although a little variable. Winter-type variety had more ecologically variable leaf primoudia,due to its stronger vernalization requirement. For winter-type variety,the primordium numbers of reproductive organs were not apparently related to the GDD accumulated prior to vernalization completion,while for spring-type variety(Yangmai 158),the numbers of different apex primordia including vegetative and reproductive organs were significantly related to the accumulated GDD during the entire phenological stages as well as before anther separation stage.
    Effect of enhanced UV-B radiation on chemical composition, fungal colonization and decomposition of spring wheat plant
    LI Yuan, ZU Yanqun, WANG Xunling
    2001, (2):  223-225. 
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    Under UV-B radiation,the CHO (soluble carbohydrate) concentration in leaves decreased significantly,while the concentrations of HCel (holocellulose) and protein in leaves and that of HCel in stems increased significantly.HCel concentration in roots did not change significantly.Under UV-B radiation,the colonization rates of Penicillium ochro-chloron and Aspergillus niger on leaves and stems increased significantly during growing phase,those of Trichoderma koningii and Aureobasidium pullulans were on the contrary,while that of Aspergillus terreus did not change obviously.After 60 and 100 days of decomposition,the decomposition rates of leaves and stems increased significantly.The decomposition rate of leaves was positively correlated with the concentration of HCel and soluble protein,but negatively with that of CHO.The decomposition rate of stems was also positively correlated with HCel concentration.Under enhanced UV-B radiation,the changes in chemical composition of spring wheat and in fungal colonization rate,and the increase in decomposition rates might resulted in a faster nutrient turnover in wheat field ecosystem and a higher nutrient storage in soil.
    Effect of photoperiod and temperature on fertility alteration of short photoperiod-low temperature induced male sterile rice
    LU Yanpeng, WAN Banghui, CHEN Xionghui, PENG Haifeng, LIANG Keqin
    2001, (2):  226-228. 
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    Short photoperiod-low temperature induced male sterile rice is a new germplasm, whose fertility alteration characteristic is contrary to that of long photoperiod and high temperature induced male sterile rice.Compared with that of Yid1s sowed under natural conditions by stages,the fertility alteration of Yid1s was observed under simulated short photoperiod treatment. The results showed that the photoperiod-sensitive stage of Yid1s occurred from differentiation of rachis primordia (phase Ⅰ) to secondary rachis-branch and spikelet primordia (phase Ⅲ).The panicles induced by appropriate short daylight treatment at photoperiod-sensitive stage tended to be completely sterile under normal temperature,but the sterile effect was weakened under high temperature. The pollen fertility of Yid1s was reduced under high or low temperature. The temperature-sensitive stages of Yid1s based on the analysis of the effects of high and low temperature on fertility were basically identical,i.e.,from pollen mother cell formation (phase Ⅴ) to single nucleus (phase Ⅶ).
    Phosphorus behavior in soil-water system of paddy field and its environmental impact
    ZHANG Zhijian, ZHU Yinmei, WANG Ke, WANG Guanghuo, DONG Liang
    2001, (2):  229-232. 
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    A field experiment with rice showed that P fertilizer application increased the concentrations of resin P in soil and total P in soil surface water,and both of them declined subsequently over time.Compared with applying mineral P fertilizer only,the integrated application of mineral-P and manure resulted in a higher resin P level within 20 days after P application.The total P concentration in soil surface water in the treatment of integrated application of mineral-P and manure was 3.4 times higher than that in the treatment of mineral-P fertilizer application only after 7 days of P application,and also,was 2.8 times higher than that in the treatment where P application rate was doubled.The potential of Ploss from surface water in the treatment of integrated application with manure was more than that in the treatment of applying-P fertilizer only.The effect of applied P sorts on P concentration in soil surface water could be ignored after 33 days of P application.Two drainages were conducted for rice growth,which caused the net P loss loading and its apparent P loss ratio in range of -0.038～0.076kg·m-2and 0.034～0.100%,respectively.To minimize P loss from rice production area,field drainage should be avoided in the initial week of P-fertilizer application or field harrowing.
    Effect of soil moisture and wetting-drying on Mn release in Ca（NO3）2-amended soils
    SI Youbin, MA Youhua, ZHANG Ligan
    2001, (2):  233-236. 
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    A study on the effects of two moisture levels (200 and 400g·kg-1) and wetting-drying on the solubility of Mn in Ca(NO3)2-amended soils showed that water regime was a factor affecting Mn availability.Easily reducible Mn was transformed into soluble and exchangeable Mn,when soil water content was high.Salt had a definite effect on the transformation of easily reducible Mn.NO3- could decrease soil redox potential,and inhibit the transformation of easily reducible Mn.Wetting-drying significantly(α<0 05) decreased the content of soil water-soluble and exchangeable Mn,while Ca(NO3)2 increased the insolubility of Mn,which might eventually lead to the deficiency of soil Mn.
    Effect of natural zeolite on nutrient preserving capability of degraded slope soil in South China
    LI Huaxing, LI Changhong, ZHANG Xinming, LIU Yuanjin, LU Weisheng
    2001, (2):  237-240. 
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    Soil column leaching experiment showed that after zeolite application,the content of nitrogen and potassium in leachate was reduced significantly,but no significant effect was detected for phosphate.This application had a positive effect on soil available nitrogen,phosphorus and potassium.It increased the content of soil AL-P and Fe-P,but did not increase the NO3--N content in leachate.
    Ecological fragility of wetlands in Sanjiang Plain
    LIU Zhenqian, LIU Hongyu, LU Xianguo
    2001, (2):  241-244. 
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    This paper presented an index system and a method for evaluating the ecological fragility of wetlands.The indexes were chosen according to the properties and the development pattern of wetland ecosystem in Sanjiang Plain,the values of weighing the relative importance of the indexes were computed by the method of “APH”(The Analytic Hierarchy Process)and the fragility level was evaluated by the method of multi-indexes.A case study showed that the ecological fragility of wetlands in Sanjiang Plain was prominently high.The availability of this method and this index system was also discussed in the paper.
    Influence of different clipping intensity and R/FR ratio in light radiation on tillering of weeping lovegrass
    WANG Shiping, WAN Changgui, Ronald E. Sosebee
    2001, (2):  245-248. 
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    Pot experiment with weeping lovegrass was conducted laboratory in the Department of Rangeland,Wildlife and Fisheries Management,Texas Tech University in 1996.The plants grown in green house were used to study the effect of different clipping intensities on tillering, and those grown in laboratory were used to study the interaction between different R/FR(red/farred)ratio of the light reaching to the lower strata of the canopy and different clipping intensities on tillering.The results show that increasing clipping intensity decreased the net gain tillers,bt R/FR ratio had no significant effect on tillering,except no clipping treatment.The compensatory growth effect of tillering did not existed at all clipping intensities,but the elongation speed of young leaves quickened with clipping intensities.It is suggested that suitable utilization,intensified utilization and no utilization were all not beneficial to the growth and development of weeping lovegrass.
    Spatial structure and pattern of Nilaparvata lugens population in large scale
    ZHOU Qiang, ZHANG Runjie, GU Dexiang
    2001, (2):  249-252. 
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    Brown planthopper(BPH),Nilaparvata lugens,is a major pest of rice.Its spatial distribution of different generations in Guangdong Province was studied by using variograms.The results showed that this population distributed in a clump pattern in rice fields during the 1st rice season.3 generations of this population had different spatial structures,with the clump range of 400km,200km and 205km respectively in the 1st rice season.The simulation distribution maps of BPH,which was interpolated by Ordinary Kriging,showed that the density of BPH populations in west Guangdong province were higher than that in the east.The effect of sampling size on the spatial structure of BPH was not significant.
    Effect of elevated atmospheric CO2 concentration on Rhopalsiphum padi population under different soil water levels
    ZHANG Jun, LIU Jing, WANG Genxuan, WANG Yafu
    2001, (2):  253-256. 
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    With the aim of forecasting the wheat-aphid relationships under different precipitation in the future atmospheric CO2 environment,the effects of different atmospheric CO2 concentration on Rhopalsiphum padi population under different soil water levels in Open-Top chambers were studied.The results showed that Rhopalsiphum padi population grew constantly with the continuous rising of atmospheric CO2 and it grew more quickly when CO2 concentration increased from 350μl·L-1 to 550μl·L-1 .In each CO2 concentration treatment,R.padi population were distinct under different soil water level,and they were the highest under 60% of field water capacity treatment.When CO2 concentration increased from 350μl·L-1 to 550μl·L-1 ,the increase of R.padi population under 60% of field water capacity treatment was higher than that under 40% and 80% treatment.When CO2 concentration increased from 550μl·L-1 to 700μl·L-1 ,the increases of R.padi population under 60% and 40% soil water treatments were the same and both higher than that under 80% treatment.These results suggested that R.padi population would grow more quickly from the beginning to the middle of the 21st century and bring more damages to the wheat in arid and semiarid area.
    Controlling effect of parasitoids on population of vegetable leaf miner Liriomyza sativae Blanchard
    LIANG Guangwen, ZHAN Genxiang, ZENG Ling
    2001, (2):  257-260. 
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    The controlling effect of parasitoids on vegetable leaf miner,Liriomyza sativae Blanchard,was evaluated by using acting factor life tables and exclusion inex of population control(EPIC).The results showed that Chrysocharis pentheus,Neuchrysocharis formosa,Chrysonotomyia okazakii,Hemiptarsenus varicornis,Chrysocharis sp.,Opius dimidiatus and Opius dissitus played an important role in controlling the population of vegetable leaf miner.The EIPCs of parasitoids were 1.23,2.73,5.98,5.92 and 5.71,respectively for the five generations of L.sativae on kidney bean planted in spring,from the 1st to the 5th generation and,for the 2nd generation in particular,they were 2.73,2.87,2.24 and 1.89,respectively on kidney bean,cowpea,luffa and cucumber,indicating that if the parasitoids were excluded,the population of the next generation of L.sativae would increase by times accordingly.The EIPC of parasitoids for the 3rd instar larvae was usually the largest among different instar larvae and pupae,and the EIPCs for the 3rd to 5th generation of L.sativae on spring kidney bean were higher than those for the 1st and the 2nd.The EIPCs of parasitoids for L.sativae on kidney bean and cowpea were larger than those on luffa and cucumber.
    Species composition and diversity of soil mesofauna in the `Holy Hills’fragmentary tropical rain forest of Xishuangbanna, China
    YANG Xiaodong, SHA Liqing
    2001, (2):  261-265. 
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    The species composition and diversity of soil mesofauna were examined in fragmented dry tropical seasonal rainforest of tow‘Holy Hills' of Dai nationality,compared with the continuous moist tropical seasonal rain forest of Nature Reserve in Xishuangbanna area.5 sample quadrats were selected along the diagonal of 20m×20m sampling plot,and the samples of litterfall and 0～3cm soil were collected from each 50cm×10cm sample quadrat.Animals in soil sample were collected by using dry-funnel(Tullgren's),were identified to their groups according to the order.The H′ index,D·G index and the pattern of relative abundance of species were used to compare the diversity of soil mesofauna.The results showed that the disturbance of vegetation and soil resulted by tropical rainforest fragmentation was the major factor affecting the diversity of soil mesofauna.Because the fragmented forest was intruded by some pioneer tree species and the “dry and warm”effect operated,this forest had more litterfall on the floor and more humus in the soil than the continuous moist rain forest.The soil condition with more soil organic matter,total N and P,higher pH value and lower soil bulk density became more favorable to the soil mesofauna.Therefore,the species richness,abundance and diversity of soil mesofauna in fragmented forests were higher than those in continuous forest,but the similarity of species composition in fragmented forest to the continuous froest was minimal.Soil mesofauna diversity in fragmented forests did not change with decreasing fragmented area,indicating that there was no species-area effect operation in this forest.The pattern of relative abundance of species in these forest soils was logarithmic series distribution.
    Toxicity of different pesticides to Haemadipsa hainana and its contorl
    TAN Enguang, LIANG Chuanjing
    2001, (2):  266-268. 
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    Laboratory determination on the toxicity of sumicidin,isoprocarb,dicofol,thiocyclam,dimethoate and glyphosate to Haemadipsa hainana showed that LD 50 for the six pesticides followed the order of sumicidin>isoprocarb>dicofol>thiocyclam>dimethoate,but glyphosate was not virulent.“Glyphosate+sumicidin”had much more toxicity.The susceptibility of H.hainana to sumicidin differed in the order of adult>juvenile>subadult.Field tests showed that the control effect of 1.5% sumicidin to H.hainana was 95.08% of total number of its population.Applied tests showed that the control effect of “Glyphosate+0.5% sumicidin” was 94.7%,and “glyphosate+1% isoprocarb”was 90.5%.“Glyphosate+pesticides”was more effective both in controlling H.hainana and in destroying its habitat weed.
    Establishment of trans-inactivation system for haloalkane dehalogenase gene in Arabidopsis thaliana
    HAO Lin, CAO Jun, FENG Shu
    2001, (2):  269-271. 
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    With haloalkane dehalogenase gene (dhlA) of Xanthobacter autothophicus as a negative selection marker,a novel trans-inactivation system for transgenes in plants was developed.After the A rabidopsis plants were transformed with dhlA, one plant was shown dhlA post-transcriptional silencing by nuclear run-off transcriptional analysis.The A rabidopsis plants containing silencing locus were crossed to those efficiently expressed dhlA,referred as a homologous transgenic locus,and 96% of F1 plants became the homologous dhlA inactivated in trans. When the F1 plants were selfed,and the silencing locus and the homologous locus were separated in some progenies,42 of the 200 progenies exhibited DhlA activity,and 158 no DhlA activity, and the proportion of the DhlA-expressing plants to the dhlA-silencing ones was 3.76 to 1,which suggested that the silencing locus inactivated in trans the homologous transgenic locus as a Mendelian dominant factor.
    Effect of EGTA and La2+ on induction of sesquiterpene cyclase gene expression in leaves of Capsicum annuum by several abiotic elicitors
    HE Shuilin, LIN Wenxiong, CHEN Rukai
    2001, (2):  272-274. 
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    To destroy Ca2+ signal system,the detached leaves of Capsicum annuum were pretreated with EGTA,a commonly used Ca2+ chelator,or La3+ ,an ion which competitively inhibits Ca2+ movement through plasma membrane channels.The induction of sesquiterpene cyclase gene expression in the pretreated pepper leaves under the treatments of CuCl2,HgCl2 and UV was conducted in this paper.The result showed that no hindrance of sesquiterpene cyclase enzyme activity was detected in the EGTA or LaCl3 pretreated leaves,compared to the controls treated with CuCl2,HgCl2,and UV without the pretreatment,while the pretreatment with EGTA enhanced the inductivity of the above exogenous abiotic elicitors on the enzyme activity.The sesquiterpene cyclase activity was also detected in leaves treated with EGTA only,and the result of Northen Blot analysis indicated that the enhancement of EGTA on the enzyme activity was due to the induction of EGTA on the gene transcription.It is suggested that there might exist other signal pipelines,in addition to the Ca2+ signal system in sesquiterpene cyclase gene expression in pepper leaves,and the mechanism of induction of abiotic elicitors on sesquiterpene cyclase in C.annuum differed from that of biotic elicitors.
    Effect of Zn2+, Cd2+and their combined on Ca, Fe and Mn uptake by wheat seedlings
    XU Guilian, WANG Huanxiao, WU Yushu, WANG Guangcan, ZHU Guanghui
    2001, (2):  275-278. 
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    The effect of Zn,Cd and their combination on Ca,Fe and Mn uptake by wheat seedlings was studied with solution culture.The result shows the Zn and Cd contents of wheat increased with increasing concentrations of Z2+ and Cd2+ in solution,while there was a difference between single and compound treatments.Zn affected Cd uptake by wheat,and Cd inhibited Zn uptake.The uptake of Ca and Mn reduced with the increase of Z2+ and Cd2+ in solution.The uptake of Fe increased with increasing Z2+ and Cd2+ concentrations in single treatment,while decreased in compound treatment.The interactive effect of Zn and Cd was also related to the parts of plants.
    An off site petroleum-contaminated soil bioremediation technology:soil composting in windrow
    JIANG Changliang, SUN Tieheng, LI Peijun, ZHANG Chungui, ZHANG Hairong, MA Xuejun, YAO Deming, YANG Guifen
    2001, (2):  279-282. 
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    With off-site bioremediation technolgy,a soil contaminated by crude oil from Liaohe Oil Field was treated on a 20×10m prepared bed.8 composting windrow units were set,each measured 8m in length,2m in width,and 0.35m in height.The results showed that when the pollutant petroleum hydrocarbon(TPH)was within the range of 4.16～7 72g·100g-1 soil,the total degradation rate of TPH reached 45.19%～56.74% after 53 days operation,which indicated that a technological basis would be provided for the bioremediation of oil-contaminated soil.
    Preliminary approach to environmental risk assessment of drainage projects during oilfield exploitation in Daqing
    YU Yanxin, CHEN Jiajun, WANG Hongqi
    2001, (2):  283-286. 
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    A qualitative analysis was made to assess the environmental risk and its impact of alternative drainage projects around Yong-5 oil-transport station at Yongle oilfield in Daqing.On the basis of this ,a method of fuzzy comprehensive assessment was applied to set up corresponding indexes,to determine hazard environmental coefficiens,and to calculate the environmental risk fuzzy assessment indexes which reflect the relative risk degrees of alternative drainage projects.The measures on environmental risk management were proposed according to the priority of alternative projects.
    Water quality of closed polyculture of penaeid shrimp with tilapia and constricted tagelus
    TIAN Xiangli, LI Deshang, DONG Shuanglin, LIU Guocai, QI Zhenxiong, LU Jing
    2001, (2):  287-292. 
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    A variety of water quality parameters were monitored in enclosures for the polyculture of penaeid shrimp with tilapia and constricted tagelus.The result showed that the environment of the polyculture systems was better than that of monoculture one. The fluctuation of DO in the water of polyculture enclosures was less violent,and their lowest values were obviously higher than those in monoculture ones.The value of COD and the number of bacteria in the water of polyculture enclosures were significantly lower than those in monoculture ones(t-test,α<0.05),showing that the amount of organic matter in the water of polyculture systems was less than that in monoculture one. The biomass of plankton and the concentration of chlorophyll-a in the polyculture enclosures were also lower,showing that the suppression of the filtering animals to the plankton was obvious.The accumulation of N and P in the sediment of polyculture enclosures was 39.76% and 51.26%,lower than those of monoculture ones, respectively;and the number of bacteria in the sediment was 7.63% lower.Therefore,it is obvious that closed culture system can greatly decrease the effluent to the coastal waters caused by the pond culture industry,and decrease the pollution to the coastal waters.
    Maintenance ration and conversion efficiency of Hyporhamphus sajori
    GUO Xuewu, TANG Qisheng
    2001, (2):  293-295. 
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    The maintenance ration and conversion efficiency of Japanese halfbeak,Hyporhamphus sajori were tested with enclosures installed in a shrimp raising pond.The results showed that there existed an evident relationship between daily ration(DR)and growth rate(GR) of the fish,GR=140.37DR-24.03.The conversion efficiency was 13.96% in biomass or 16.12% in energy.The maintenance ration was 17.12% and 20.39% of body weight in terms of growth rate and specific growth rate,respectively,indicating that it could be deduced from growth rate quite differently from that from specific growth rate in the same experiment.The abnormal growth rate appeared when daily ration was below 3.30% of body weight,implied that Japanese halfbeak may get other food resources besides supplied net zooplankton.
    Technique of implanting 17α-methyltestosterone to induce the sex reversal of Epinephelus malabaricus
    CHEN Guohua, ZHANG Ben
    2001, (2):  296-298. 
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    This paper discussed the method of implanting 17α-methyltestosterone to induce the sex reversal of Epinephelus malabaricus, which included chemical treatment, dosage and operating on the fish. After twice implanting of exogenous hormone, the mature females of 3 years old were transformed into functional males. Sperm could be squeezed from 58% of the fish on 139 days after operating,and from 100% on 301days. When the functional males were used for artificial breeding, the parent fish spawned in a natural way, and 71.03 million larvae were hatched in the two years of 1999～2000. The larvae were used for rearing of fish fry, from which normally growing young fish was get.It is believed that the method of implanting exogenous hormone to induce the sex reversal of E.malabaricus is easy and stable, which can satisfy the requirement of artificial breeding in factories.
    Effect of silver carp stocking and fertilization on plankton community in enclosures in saline-alkaline ponds
    ZHAO Wen, DONG Shuanglin, ZHANG Zhaoqi, LI Deshang
    2001, (2):  299-303. 
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    The effect of silver carp (Hypophthalmichthys molitrix) stocking and fertilization on plankton community of enclosures ecosystem in saline-alkaline ponds were studied.After stocking silver carp in enclosures,the abundance,chlorophyll-a content and primary productivity of phytoplankton increased,and the biomass of phytoplankton was mainly composed by small species,such as diatom and green algae.Moreover,Euglnophyta and Chrysophyta were also sub-dominant species.The biomass of zooplankton decreased with fish stocking,and that of Cladocera was greater in control than in fish-culture enclosures.Zooplankton community was dominated by larger species such as Daphnia carinata in control enclosures.Fertilization,especially applying inorganic fertilizer,significantly increased the abundance and primay productivity of phytoplankton and the biomass of zooplankton.Although the biomass of plankton in the enclosures applied organic fertilizer was greater than that of control enclosures,the primary productivity and chlorophyll-a content of phytoplankton,the diversity index of plankton,and the P/R ratio were very low,and thus,silver carp grew slowly.The effect of filter feeding fish and applying fertilizer on the structure of plankton community was also discussed.
    Forest soil seed bank and natural regeneration
    YANG Yuejun, SUN Xangyang, WANG Paoping
    2001, (2):  304-308. 
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    The characteristics of temporal dynamics and spatial distribution of forest soil seed bank and their effects on natural regeneration were reviewed in this paper.The density of the seed bank of forest soil,which is affected by the types and ages of forest,is lower than that of cultivated land and grassplot,and can vary widely.The extent to which the composition of forest soil seed bank is influenced by its counterpart plantation depends on the stages of succession.The dynamics of forest soil seed bank is the combined effect of periodical and random factors.It is suggested that forest soil seed bank is the material base of forest regeneration,and the configuration and function of forest soil seed bank would influence the ability and the direction of natural forest regeneration.According to the characteristics of forest soil seed bank and obstructive factors influencing regeneration,some artificial measures can be adopted to accelerate natural regeneration.Studies on the forest soil seed bank should focus on the application of basic theories of disturbed ecology,and regard the reconstruction of degenerative ecosystem and the succession of populations in the ecotone as the main contents to study.As for the research method,it is advisable to employ long-term and located observations.
    Coarse woody debris and its function in forest ecosystem
    HOU Ping, PAN Cunde
    2001, (2):  309-314. 
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    Coarse woody debris (CWD) is an important structural and functional element in forest ecosystem.In this paper,the definition,dynamics,and role of CWD in a forest ecosystem were overviewed.CWD include all woody debris above and under the ground with a diameters ≥2.5cm,and mainly comes from the dead trees resulted from competition and disturbances.The biomass of CWD changes like“U”form along with the development of a forest community.The decay rate of CWD is determined by the compound course of the respiration and natural fragmentation.Insects and microorganisms play an important role in the course.CWD basically has two functions in an ecosystem.One is as the nutrition pool for some living creatures,and the other is that the large CWD can form some special habitats for animals and plants.Conclusively these two functions are helpful to reserve the biodiversity and the integrity of ecological process in a natural ecosystem.Gaps are formed while dead trees falling down,and all gaps in a forest succeed one another randomly in the development of a forest ecosystem,which pushes the inner circulation of the forest.Because of the vital roles of CWD in a forest ecosystem,much more attention should be paid in the management of forest ecosystem.
    Landscape changes of ecotone of temperate and sub-tropical zone and its ecological importance
    HOU Xiangyang
    2001, (2):  315-318. 
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    The change process of ecotone of temperate and subtropical zone and its effect on development, transformation and permeation of chinese agriculture and techniques were discussed in this paper from the viewpoint of landscape ecology. In historical time, the boundary of the ecotone changed northward and southward as climate changed, which changed southward 1～2 latitude in cold period and northward 1～2 latitude in warm period. The ecotone had an obvious environment diversity and strong sensibility, and played important role as a landscape conduit and barrier in aspects of chinese agricultural heterogeneous permeation and heterogeneity creation of agricultural techniques and cultures.
    Community characteristics of benthonic animals and its relationship to environmental factors in the Nanhu Lake, Changchun
    SUN Gang, SHENG Lianxi, LI Mingquan
    2001, (2):  319-320. 
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    There are only 21 species of benthonic animals in the Nanhu Lake,Changchun.The dominant species in the benthos community are obvious,and the individual quantity of Limnodrilus hoffmeisteri,Branchiura sowerbyi,and Tendipus plumosus accounts for 87% of the total individual quantity of all benthonic animals.It indicates that the water in the Nanhu Lake is suffering serious organic pollution,and belongs to an eutrophic lake.The peak values of benthos biomass and energy are found in July(48 23gWW·m-2and 241 16kJ·m-2respectively),while the maximum individual quantity is appeared in May(401ind·m-2).The distribution of Oligochaeta and aquatic insects has a significant positive correlation to organic content in the sediment(α<0 05).The community structure of benthonic animals reflects adequately the feature of the Nanhu Lake as an eutrophic lake in temperate zone.
    Grey correlation and cluster analysis on relationship between Cercidiphyllum japonicum community and its environment
    PAN Kaiwen, LIU Zhaoguang
    2001, (2):  161-167. 
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    The relationship between 10 years old C. japonicum plantation forest community and its environmental conditions was studied by grey correlation method and cluster analysis.The reuslts showed that there existed closer relations among soil organic matter,available Ca,Fe,Mg and N.Except for N and Mn,all soil available elements tested had no direct impact on the absorption and accumulation of corresponding elements by the community.The tree species in different habitats was found to absorb soil elements selectively to some extent.The factors affecting the basal diameter,DBH,height and biomass of C.japonicum could be lined as soil chemical characteristics>soil physical properties>climate factors,in which,available P had little impact on the growth of C.japonicum .It is suggested that C.japonicum could be restored in the area with higher air moisture and with fertile porous soil between elevation of 2200～2700m.
    Articles
    Interspecific association of dominant species in Betula luminiferanatural forest communities of Shaowu, Fujian Province
    LI Jianmin, XIE Fang, CHEN Cunji, ZHANG Siyu, XIAO Rihong
    2001, (2):  168-170. 
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    x2test with 2?2 contingency table and Jaccard indices shows that the interspecific association of 16 dominant species in Betula luminifera communities of Shaowu, Fujian Province was of little significant level with few exceptions. The relationships between B.luminifera and Phyllostachys pubescens ,and B. luminifera and Alniphyllum fortunei were significantly positive,showing that there was a high association degree between B.luminifera and Schima superba, B.luminifera, and Castanea henrgi, and B.luminifera and Pinus massoniana based on Jaccard indices.
    Growth analysis on the competition-density effect in Cunninghamia lanceolata stands
    XUE Li, HAGIHARA Akio
    2001, (2):  171-174. 
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    The competition density (C D) effect in Cunninghamia lanceolata stands was analyzed by using the reciprocal equation 1/ w=Aρ+B, where w and ρ represent mean stem volume and density,respectively,the C D curve given by the reciprocal equation on logarithmic coordinates shifted upward with time.With the increase of physical time t the biological time τ defined as the integral of λ(t) ,the growth coefficient in general logistic growth curve,tended to increase to the maximum.The coefficients A and B included in the reciprocal equation were calculated at each growth stage. With increasing τ, the coefficient A increased abruptly up to a maximum value,and then tended to decrease gradually to a constant level, whereas the coefficient B decreased exponentially,and tended to close to zero. The coefficient of growth λ(t) decreased with increasing stand age.
    Physiological and growth responses of Sabina vulgaris to disturbance of leaf removal
    HE Weiming
    2001, (2):  175-178. 
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    To examine the physiological and growth responses of Sabina vulgaris to natural disturbance, a field experiment to simulate the grazing and pest disturbance was conducted in Maowusu sandy land through artificially removing leaves.The disturbance of leaf removal could modify the species’ diurnal physiological dynamics through changing the timing of extreme values,and moreover,change the average daily values of physiological indexes significantly.Leaf removal could affect the growth traits,but not biomass allocation significantly.The consequences of the distrubance were confined by its means and intensity,and there existed significant differences in sensitivity of different physiological and growth characteristics e.g.,net photosynthesis rate and transpiration rate to leaf removal.The disturbance of leaf removal,especially that of old leaf removal,had compensation effects.Therefore,moderately removing the leaves on the shoots with less than 2 years old could enhance the growth and the biomass accumulation of curent-year shoots.
    Characteristic analysis on different thermal active surfaces in canopy gap of tropical secondary forest
    ZHANG Yiping, WANG Jinxin, MA Youxin, LIU Yuhong
    2001, (2):  179-184. 
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    Microclimatic measurements were conducted in the canopy gap of tropical secondary forest in Xishuangbanna in fog-cool and dry-hot season.The daytime thermal effect of different thermal active surface in the canopy gap was discussed,and the variations of trunk surface temperature near gap edge and of surface temperature on the gap were analyzed.The result shows that the woody-wall surface is new thermal active surface on the vicinage of canopy gap,with the exception of the forest canopy surface, soil surface in the forest gap,and soil surface of the interior. Because of the influence of season,situs and time,the thermal effect of different thermal active surface of gap was significant different. Being subject to fog, the soil surface on the center of canopy gap is an important thermal active surface in the morning;while in the midday and afternoon,because of the influence of incident radiation, the woody wall and soil surface of edge on the east and the woody wall surface of edge on the north are the key thermal active surface of the canopy gap. In the midday,the thermal active was salient on the surface of gap,and in the afternoon,it was salient on the woody wall. The thermal variations of canopy gap of forest are controlled by the thermal characteristics of different thermal active surfaces and by their interaction,affecting the growth of plants.
    Relationship between water supply and consumption of main planting tree species of protection forests in loess area of western Shanxi Province
    WEI Tianxing, YU Xinxiao, ZHU Jinzhao, WU Bin
    2001, (2):  185-189. 
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    Based on three years point-fixed observation,this paper analyzed the relationship between water supply and consumption of black locust(Robinia pseudoscacia L.)and Chinese pine(Pinus tabulaeformis Carr.),the main tree species of protection forests in the loess area of the western Shanxi Province.In April,May and June,the water supply was less than water consumption,while in raining season,the water supply was abundant,and the water storage in soil was increased. During dry seasons and years, more water consumption and less available water supply occurred in high-density stand,showing a serious water deficiency. The water deficiency was in order of south-facing slope>semi-south-facing slope>north-facing slope.The study shows that water consumption characters coefficient could be used as an index to indicate the growth pattern of trees,and the relationship between water supply and consumption.
    Landscape structure and greenland spatial pattern in workshop district of Wuhan Iron and Steel Company
    ZHOU Zhixiang, SHAO Tianyi, ZHOU Xiaoqing, HE Jicheng
    2001, (2):  190-194. 
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    The landscape structure and greenland spatial pattern in the workshop district of Wuhan Iron and Steel Company were investigated and analyzed on the basis of landscape ecological theory. The results showed that the main parts of the landscape structure were the artificial landscape elements such as building and concrete covering patches, highway and railway bed corridors, and industrial reservations. All of these artificial landscape elements accounted for 74.37% of patch area and 57.70% of patch dominance. In the landscape, the building and concrete covering land had the maximum percentage of patch area (56.43%) and the maximum dominance (35.59%).The special purpose greenlands had the highest fragmentation index (5.0591 ind穐m-2) and the wide-ranging distribution. The corridor density (13.78 km穔m-2) was high, and the highway had more effects on landscape than the railway.All the results reflected not only the essential landscape features of industrial region,but also the rational trend of landscape structure in the workshop district of Wuhan Iron and Steel Company. In the greenland, the road greenbelts had the maximum patch number, area percentage (66.07%), and dominance (75.31%), the shelter forests being mainly composed of tree species had high patch average area (8454.45m2) and environmental benefit, and the ornamental greenlands had abundant plant species and varied scenery. The greenland system was initially formed by four afforestation districts,using shelter forests and ornamental greenlands in large patch as a center connected by road greenbelts. It should be attached importance to the relatively high dominance of wild grasslands, the low area percentage of shelter forests and the imperfect road greenbelts to develop the uncovered lands and to improve the quality of the greenland system.
    Articles
    Evaluation on comprehensive benefits of different regulation models of agroforestry ecosystem in snail river beach
    SUN Qixiang, WU Zemin, WEI Chaoling, PENG Zhenhua
    2001, (2):  195-198. 
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    The economic,ecological,social and comprehensive benefits of different regulation models of agroforestry ecosystem in Nangeng river beach were evaluated by AHP.The resuls showed that agroforestry ecosystem was significantly superior to reed(Phragmites communis)system.Different regulation models of agroforestry ecosystem had different benefits.The sheet-thinning model had the highest economic,social,and comprehensive benefits,and it was the optimal regulation model.For all thinning models,the key approach to further raise benefits was to choose some intercrop variations,which had a high economic value,especially a high ratio of output to input.For no-thinning model,keeping on intercropping was the effective measure to raise the social and comprehensive benefits.
    Relationship between atmospheric temperature and growth characteristics of main edible grapes in South China
    DING Zhien, WEI Chaoling
    2001, (2):  199-204. 
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    The study shows that there existed a significant relationship between the new branch growth of grapes and temperature, especially effective accumulate temperature. Kyoho had the fastest new branch growth rate among all varieties,which was 0.43433cm in length with raising 10℃ while effective accumulate temperature was over 190.68℃. Mixiangbao had the slowest new branch growth rate,which was 0.17150cm in length with raising 10℃ while effective accumulate temperature was over 367.19℃.The economic properties and quality in variety character were researched by fuzzy valuation. The results showed that Kyoho, Jingya, Fujiminori, Mixiangbao, and Longbao were worthy of spreading,while Zizhenxiang would be limited in production,and Wase takasumi and Heifeng should be eliminated through selection.
    Effect of plastic film mulching on crop yield and nitrogen efficiency in semiarid areas
    LI Shiqing, LI Fengmin, SONG Qiuhua, WANG Jun
    2001, (2):  205-209. 
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    The effect of plastic film mulching,water storage in soil profile before sowing,and nitrogen fertilization on crop yield and nitrogen efficiency was examined in this paper.The study site was on the cultivated lossial soil in semiarid areas with 415mm of annual rainfall and the test crop was spring wheat,Triticum aestivum.In order to study the effect of plastic film mulching,4 levels of mulching were designed,including mulching of 0,30 and 60 days after sowing and mulching over the whole growing period.The results showed that increase of soil water storage,plastic film mulching and nitrogen fertilization increased crop yield significantly(α<0.01),and their effect followed in the order of nitrogen fertilization>increase of water storage>plastic film mulching.The effect of mulching on crop yield varied with water storage,nitrogen fertilization and mulching periods.When the water storage was low,there was no significant difference in crop yield between mulching and no mulching,although mulching increased crop yield slightly,and the nitrogen efficiency was higher for no mulching and mulching 30 days.When the water storage was high,the difference between the yield of muching 60 days and no mulching was significant,but no difference in nitrogen efficiency was found for mulching 30 days,60 days and over whole growing period.It was suggested that mulching over whole growing period was of less significance in practice.
    State of soil available sulphur and its requirement along Huaihe River region
    YU Zhongxiang, ZHANG Chenglin, WANG Shijia
    2001, (2):  210-212. 
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    This paper investigated the available S contents of yellow cinnamon soil,fluvisol,shajiang black soil and paddy soil,which were developed from loessial ancient-river alluyium,recent loess-flooding deposit,and Xiashu loess.The input and output,and the abundance and deficiency of soil available S were studied in combination with the mode of land utilization and fertilization,and the soil demands of S was predicted.The results showed that the content of soil available S was decreased in the order of paddy soil>shajiang black soil>yellow cinnamon soil>fluvisol,and there was more S in irrigated land than in dry field in case of different land utilization.From the viewpoint of parent material,the deficiency frequency of soil available S was in the order of loessial ancient-river alluvium>Xiashu loess>recent loess-flooding deposit,and the potential deficiency frequency of S was loessial ancient-river alluvium>recent loess-flooding>Xiashu loess.As for soil type,the deficiency frequency of soil available S was in the order of deposit shajiang black soil>yellow cinnamon soil>fluvisol>paddy soil,and the potential deficiency frequency of S was paddy soil>fluvisol>shajiang black soil>yellow cinnamon soil.Shajiang black soil had the largest area of lacking available S,which amounted to 7.0?104hm2,yellow cinnamon soil had an area of 2.0?104hm2,and fluvisol was 6000hm2.The total area of lacking S was 9.6?104hm2,accounted for 25.06% of total cultivated area.The total area of potentially lacking S was 1.6?105hm2,accounted for 42.04% of the total.According to the current available S content in soils and the S demands for high yielding crops,the S demands of 3.8?105hm2 farmland in three counties and one district of Bengbu was about 3.0 ?106kg and 1.2?106kg in the recent and far future,respectively.
    Effect of NPK and B supply levels on boron uptake and biological properties of different genotypic oilseed rape
    LOU Yunsheng, YANG Yuai
    2001, (2):  213-217. 
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    Pot experiment was conducted to study the boron absorption by oilseed rape(Brassica napus),the mechanism of its resistance to boron deficiency,and the effect of boron deficiency on its biological properties under different NPK supply levels.The results indicated that under boron deficiency,increasing NPK supply aggravated boron deficiency symptoms,which led to the decrease of leaf area and its growth rate and nitrate reductase activity(NRA) and the increase of chlorophyll(a+b) content at seedling stage,and the decrease of the number of productive branches and pods of each plant and seed yield at maturity.It was suggested that the ratio of boron concentration in youngest open leaves(YOL)to youngest mature leaves(YML) at seedling stage could be an index to judge the boron mobility in plants of different genotypic oilseed rape.Boron mobility and its utilization efficiency were one of the important nutritional mechanisms responsible for the difference in response of different genotypic oilseed rapes to boron deficiency.
    Effects of different varieties and sowing dates on development stages of wheat
    LI Cundong, CAO Weixing, DAI Tingbo, YAN Meichun
    2001, (2):  218-222. 
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    The effects of different sowing dates and varieties on development stages of wheat were studied in this paper.The results showed that the emergence of tiller was mainly regulated by the ecological factors rather than the genetic effect.For winter-type variety(Jing 411),most variable growth duration throughout the entire growth cycle occurred from tillering to jointing. In contrast,the timing of single ridge stage was determined by genotypic effect rather than ecological factors.Single ridge to double ridge stage was most sensitive to vernalization progress.For spring sowing of winter-type variety,the vernalization process could last till floral primordium differentiation stage. The corresponding relationships existed between phenological and spike development stages in different sowing dates,although a little variable. Winter-type variety had more ecologically variable leaf primoudia,due to its stronger vernalization requirement. For winter-type variety,the primordium numbers of reproductive organs were not apparently related to the GDD accumulated prior to vernalization completion,while for spring-type variety(Yangmai 158),the numbers of different apex primordia including vegetative and reproductive organs were significantly related to the accumulated GDD during the entire phenological stages as well as before anther separation stage.
    Effect of enhanced UV-B radiation on chemical composition, fungal colonization and decomposition of spring wheat plant
    LI Yuan, ZU Yanqun, WANG Xunling
    2001, (2):  223-225. 
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    Under UV-B radiation,the CHO (soluble carbohydrate) concentration in leaves decreased significantly,while the concentrations of HCel (holocellulose) and protein in leaves and that of HCel in stems increased significantly.HCel concentration in roots did not change significantly.Under UV-B radiation,the colonization rates of Penicillium ochro-chloron and Aspergillus niger on leaves and stems increased significantly during growing phase,those of Trichoderma koningii and Aureobasidium pullulans were on the contrary,while that of Aspergillus terreus did not change obviously.After 60 and 100 days of decomposition,the decomposition rates of leaves and stems increased significantly.The decomposition rate of leaves was positively correlated with the concentration of HCel and soluble protein,but negatively with that of CHO.The decomposition rate of stems was also positively correlated with HCel concentration.Under enhanced UV-B radiation,the changes in chemical composition of spring wheat and in fungal colonization rate,and the increase in decomposition rates might resulted in a faster nutrient turnover in wheat field ecosystem and a higher nutrient storage in soil.
    Effect of photoperiod and temperature on fertility alteration of short photoperiod-low temperature induced male sterile rice
    LU Yanpeng, WAN Banghui, CHEN Xionghui, PENG Haifeng, LIANG Keqin
    2001, (2):  226-228. 
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    Short photoperiod-low temperature induced male sterile rice is a new germplasm, whose fertility alteration characteristic is contrary to that of long photoperiod and high temperature induced male sterile rice.Compared with that of Yid1s sowed under natural conditions by stages,the fertility alteration of Yid1s was observed under simulated short photoperiod treatment. The results showed that the photoperiod-sensitive stage of Yid1s occurred from differentiation of rachis primordia (phase Ⅰ) to secondary rachis-branch and spikelet primordia (phase Ⅲ).The panicles induced by appropriate short daylight treatment at photoperiod-sensitive stage tended to be completely sterile under normal temperature,but the sterile effect was weakened under high temperature. The pollen fertility of Yid1s was reduced under high or low temperature. The temperature-sensitive stages of Yid1s based on the analysis of the effects of high and low temperature on fertility were basically identical,i.e.,from pollen mother cell formation (phase Ⅴ) to single nucleus (phase Ⅶ).
    Phosphorus behavior in soil-water system of paddy field and its environmental impact
    ZHANG Zhijian, ZHU Yinmei, WANG Ke, WANG Guanghuo, DONG Liang
    2001, (2):  229-232. 
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    A field experiment with rice showed that P fertilizer application increased the concentrations of resin P in soil and total P in soil surface water,and both of them declined subsequently over time.Compared with applying mineral P fertilizer only,the integrated application of mineral-P and manure resulted in a higher resin P level within 20 days after P application.The total P concentration in soil surface water in the treatment of integrated application of mineral-P and manure was 3.4 times higher than that in the treatment of mineral-P fertilizer application only after 7 days of P application,and also,was 2.8 times higher than that in the treatment where P application rate was doubled.The potential of Ploss from surface water in the treatment of integrated application with manure was more than that in the treatment of applying-P fertilizer only.The effect of applied P sorts on P concentration in soil surface water could be ignored after 33 days of P application.Two drainages were conducted for rice growth,which caused the net P loss loading and its apparent P loss ratio in range of -0.038～0.076kg·m-2and 0.034～0.100%,respectively.To minimize P loss from rice production area,field drainage should be avoided in the initial week of P-fertilizer application or field harrowing.
    Effect of soil moisture and wetting-drying on Mn release in Ca（NO3）2-amended soils
    SI Youbin, MA Youhua, ZHANG Ligan
    2001, (2):  233-236. 
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    A study on the effects of two moisture levels (200 and 400g·kg-1) and wetting-drying on the solubility of Mn in Ca(NO3)2-amended soils showed that water regime was a factor affecting Mn availability.Easily reducible Mn was transformed into soluble and exchangeable Mn,when soil water content was high.Salt had a definite effect on the transformation of easily reducible Mn.NO3- could decrease soil redox potential,and inhibit the transformation of easily reducible Mn.Wetting-drying significantly(α<0 05) decreased the content of soil water-soluble and exchangeable Mn,while Ca(NO3)2 increased the insolubility of Mn,which might eventually lead to the deficiency of soil Mn.
    Effect of natural zeolite on nutrient preserving capability of degraded slope soil in South China
    LI Huaxing, LI Changhong, ZHANG Xinming, LIU Yuanjin, LU Weisheng
    2001, (2):  237-240. 
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    Soil column leaching experiment showed that after zeolite application,the content of nitrogen and potassium in leachate was reduced significantly,but no significant effect was detected for phosphate.This application had a positive effect on soil available nitrogen,phosphorus and potassium.It increased the content of soil AL-P and Fe-P,but did not increase the NO3--N content in leachate.
    Ecological fragility of wetlands in Sanjiang Plain
    LIU Zhenqian, LIU Hongyu, LU Xianguo
    2001, (2):  241-244. 
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    This paper presented an index system and a method for evaluating the ecological fragility of wetlands.The indexes were chosen according to the properties and the development pattern of wetland ecosystem in Sanjiang Plain,the values of weighing the relative importance of the indexes were computed by the method of “APH”(The Analytic Hierarchy Process)and the fragility level was evaluated by the method of multi-indexes.A case study showed that the ecological fragility of wetlands in Sanjiang Plain was prominently high.The availability of this method and this index system was also discussed in the paper.
    Influence of different clipping intensity and R/FR ratio in light radiation on tillering of weeping lovegrass
    WANG Shiping, WAN Changgui, Ronald E. Sosebee
    2001, (2):  245-248. 
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    Pot experiment with weeping lovegrass was conducted laboratory in the Department of Rangeland,Wildlife and Fisheries Management,Texas Tech University in 1996.The plants grown in green house were used to study the effect of different clipping intensities on tillering, and those grown in laboratory were used to study the interaction between different R/FR(red/farred)ratio of the light reaching to the lower strata of the canopy and different clipping intensities on tillering.The results show that increasing clipping intensity decreased the net gain tillers,bt R/FR ratio had no significant effect on tillering,except no clipping treatment.The compensatory growth effect of tillering did not existed at all clipping intensities,but the elongation speed of young leaves quickened with clipping intensities.It is suggested that suitable utilization,intensified utilization and no utilization were all not beneficial to the growth and development of weeping lovegrass.
    Spatial structure and pattern of Nilaparvata lugens population in large scale
    ZHOU Qiang, ZHANG Runjie, GU Dexiang
    2001, (2):  249-252. 
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    Brown planthopper(BPH),Nilaparvata lugens,is a major pest of rice.Its spatial distribution of different generations in Guangdong Province was studied by using variograms.The results showed that this population distributed in a clump pattern in rice fields during the 1st rice season.3 generations of this population had different spatial structures,with the clump range of 400km,200km and 205km respectively in the 1st rice season.The simulation distribution maps of BPH,which was interpolated by Ordinary Kriging,showed that the density of BPH populations in west Guangdong province were higher than that in the east.The effect of sampling size on the spatial structure of BPH was not significant.
    Effect of elevated atmospheric CO2 concentration on Rhopalsiphum padi population under different soil water levels
    ZHANG Jun, LIU Jing, WANG Genxuan, WANG Yafu
    2001, (2):  253-256. 
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    With the aim of forecasting the wheat-aphid relationships under different precipitation in the future atmospheric CO2 environment,the effects of different atmospheric CO2 concentration on Rhopalsiphum padi population under different soil water levels in Open-Top chambers were studied.The results showed that Rhopalsiphum padi population grew constantly with the continuous rising of atmospheric CO2 and it grew more quickly when CO2 concentration increased from 350μl·L-1 to 550μl·L-1 .In each CO2 concentration treatment,R.padi population were distinct under different soil water level,and they were the highest under 60% of field water capacity treatment.When CO2 concentration increased from 350μl·L-1 to 550μl·L-1 ,the increase of R.padi population under 60% of field water capacity treatment was higher than that under 40% and 80% treatment.When CO2 concentration increased from 550μl·L-1 to 700μl·L-1 ,the increases of R.padi population under 60% and 40% soil water treatments were the same and both higher than that under 80% treatment.These results suggested that R.padi population would grow more quickly from the beginning to the middle of the 21st century and bring more damages to the wheat in arid and semiarid area.
    Controlling effect of parasitoids on population of vegetable leaf miner Liriomyza sativae Blanchard
    LIANG Guangwen, ZHAN Genxiang, ZENG Ling
    2001, (2):  257-260. 
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    The controlling effect of parasitoids on vegetable leaf miner,Liriomyza sativae Blanchard,was evaluated by using acting factor life tables and exclusion inex of population control(EPIC).The results showed that Chrysocharis pentheus,Neuchrysocharis formosa,Chrysonotomyia okazakii,Hemiptarsenus varicornis,Chrysocharis sp.,Opius dimidiatus and Opius dissitus played an important role in controlling the population of vegetable leaf miner.The EIPCs of parasitoids were 1.23,2.73,5.98,5.92 and 5.71,respectively for the five generations of L.sativae on kidney bean planted in spring,from the 1st to the 5th generation and,for the 2nd generation in particular,they were 2.73,2.87,2.24 and 1.89,respectively on kidney bean,cowpea,luffa and cucumber,indicating that if the parasitoids were excluded,the population of the next generation of L.sativae would increase by times accordingly.The EIPC of parasitoids for the 3rd instar larvae was usually the largest among different instar larvae and pupae,and the EIPCs for the 3rd to 5th generation of L.sativae on spring kidney bean were higher than those for the 1st and the 2nd.The EIPCs of parasitoids for L.sativae on kidney bean and cowpea were larger than those on luffa and cucumber.
    Species composition and diversity of soil mesofauna in the `Holy Hills’fragmentary tropical rain forest of Xishuangbanna, China
    YANG Xiaodong, SHA Liqing
    2001, (2):  261-265. 
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    The species composition and diversity of soil mesofauna were examined in fragmented dry tropical seasonal rainforest of tow‘Holy Hills' of Dai nationality,compared with the continuous moist tropical seasonal rain forest of Nature Reserve in Xishuangbanna area.5 sample quadrats were selected along the diagonal of 20m×20m sampling plot,and the samples of litterfall and 0～3cm soil were collected from each 50cm×10cm sample quadrat.Animals in soil sample were collected by using dry-funnel(Tullgren's),were identified to their groups according to the order.The H′ index,D·G index and the pattern of relative abundance of species were used to compare the diversity of soil mesofauna.The results showed that the disturbance of vegetation and soil resulted by tropical rainforest fragmentation was the major factor affecting the diversity of soil mesofauna.Because the fragmented forest was intruded by some pioneer tree species and the “dry and warm”effect operated,this forest had more litterfall on the floor and more humus in the soil than the continuous moist rain forest.The soil condition with more soil organic matter,total N and P,higher pH value and lower soil bulk density became more favorable to the soil mesofauna.Therefore,the species richness,abundance and diversity of soil mesofauna in fragmented forests were higher than those in continuous forest,but the similarity of species composition in fragmented forest to the continuous froest was minimal.Soil mesofauna diversity in fragmented forests did not change with decreasing fragmented area,indicating that there was no species-area effect operation in this forest.The pattern of relative abundance of species in these forest soils was logarithmic series distribution.
    Toxicity of different pesticides to Haemadipsa hainana and its contorl
    TAN Enguang, LIANG Chuanjing
    2001, (2):  266-268. 
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    Laboratory determination on the toxicity of sumicidin,isoprocarb,dicofol,thiocyclam,dimethoate and glyphosate to Haemadipsa hainana showed that LD 50 for the six pesticides followed the order of sumicidin>isoprocarb>dicofol>thiocyclam>dimethoate,but glyphosate was not virulent.“Glyphosate+sumicidin”had much more toxicity.The susceptibility of H.hainana to sumicidin differed in the order of adult>juvenile>subadult.Field tests showed that the control effect of 1.5% sumicidin to H.hainana was 95.08% of total number of its population.Applied tests showed that the control effect of “Glyphosate+0.5% sumicidin” was 94.7%,and “glyphosate+1% isoprocarb”was 90.5%.“Glyphosate+pesticides”was more effective both in controlling H.hainana and in destroying its habitat weed.
    Establishment of trans-inactivation system for haloalkane dehalogenase gene in Arabidopsis thaliana
    HAO Lin, CAO Jun, FENG Shu
    2001, (2):  269-271. 
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    With haloalkane dehalogenase gene (dhlA) of Xanthobacter autothophicus as a negative selection marker,a novel trans-inactivation system for transgenes in plants was developed.After the A rabidopsis plants were transformed with dhlA, one plant was shown dhlA post-transcriptional silencing by nuclear run-off transcriptional analysis.The A rabidopsis plants containing silencing locus were crossed to those efficiently expressed dhlA,referred as a homologous transgenic locus,and 96% of F1 plants became the homologous dhlA inactivated in trans. When the F1 plants were selfed,and the silencing locus and the homologous locus were separated in some progenies,42 of the 200 progenies exhibited DhlA activity,and 158 no DhlA activity, and the proportion of the DhlA-expressing plants to the dhlA-silencing ones was 3.76 to 1,which suggested that the silencing locus inactivated in trans the homologous transgenic locus as a Mendelian dominant factor.
    Effect of EGTA and La2+ on induction of sesquiterpene cyclase gene expression in leaves of Capsicum annuum by several abiotic elicitors
    HE Shuilin, LIN Wenxiong, CHEN Rukai
    2001, (2):  272-274. 
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    To destroy Ca2+ signal system,the detached leaves of Capsicum annuum were pretreated with EGTA,a commonly used Ca2+ chelator,or La3+ ,an ion which competitively inhibits Ca2+ movement through plasma membrane channels.The induction of sesquiterpene cyclase gene expression in the pretreated pepper leaves under the treatments of CuCl2,HgCl2 and UV was conducted in this paper.The result showed that no hindrance of sesquiterpene cyclase enzyme activity was detected in the EGTA or LaCl3 pretreated leaves,compared to the controls treated with CuCl2,HgCl2,and UV without the pretreatment,while the pretreatment with EGTA enhanced the inductivity of the above exogenous abiotic elicitors on the enzyme activity.The sesquiterpene cyclase activity was also detected in leaves treated with EGTA only,and the result of Northen Blot analysis indicated that the enhancement of EGTA on the enzyme activity was due to the induction of EGTA on the gene transcription.It is suggested that there might exist other signal pipelines,in addition to the Ca2+ signal system in sesquiterpene cyclase gene expression in pepper leaves,and the mechanism of induction of abiotic elicitors on sesquiterpene cyclase in C.annuum differed from that of biotic elicitors.
    Effect of Zn2+, Cd2+and their combined on Ca, Fe and Mn uptake by wheat seedlings
    XU Guilian, WANG Huanxiao, WU Yushu, WANG Guangcan, ZHU Guanghui
    2001, (2):  275-278. 
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    The effect of Zn,Cd and their combination on Ca,Fe and Mn uptake by wheat seedlings was studied with solution culture.The result shows the Zn and Cd contents of wheat increased with increasing concentrations of Z2+ and Cd2+ in solution,while there was a difference between single and compound treatments.Zn affected Cd uptake by wheat,and Cd inhibited Zn uptake.The uptake of Ca and Mn reduced with the increase of Z2+ and Cd2+ in solution.The uptake of Fe increased with increasing Z2+ and Cd2+ concentrations in single treatment,while decreased in compound treatment.The interactive effect of Zn and Cd was also related to the parts of plants.
    An off site petroleum-contaminated soil bioremediation technology:soil composting in windrow
    JIANG Changliang, SUN Tieheng, LI Peijun, ZHANG Chungui, ZHANG Hairong, MA Xuejun, YAO Deming, YANG Guifen
    2001, (2):  279-282. 
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    With off-site bioremediation technolgy,a soil contaminated by crude oil from Liaohe Oil Field was treated on a 20×10m prepared bed.8 composting windrow units were set,each measured 8m in length,2m in width,and 0.35m in height.The results showed that when the pollutant petroleum hydrocarbon(TPH)was within the range of 4.16～7 72g·100g-1 soil,the total degradation rate of TPH reached 45.19%～56.74% after 53 days operation,which indicated that a technological basis would be provided for the bioremediation of oil-contaminated soil.
    Preliminary approach to environmental risk assessment of drainage projects during oilfield exploitation in Daqing
    YU Yanxin, CHEN Jiajun, WANG Hongqi
    2001, (2):  283-286. 
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    A qualitative analysis was made to assess the environmental risk and its impact of alternative drainage projects around Yong-5 oil-transport station at Yongle oilfield in Daqing.On the basis of this ,a method of fuzzy comprehensive assessment was applied to set up corresponding indexes,to determine hazard environmental coefficiens,and to calculate the environmental risk fuzzy assessment indexes which reflect the relative risk degrees of alternative drainage projects.The measures on environmental risk management were proposed according to the priority of alternative projects.
    Water quality of closed polyculture of penaeid shrimp with tilapia and constricted tagelus
    TIAN Xiangli, LI Deshang, DONG Shuanglin, LIU Guocai, QI Zhenxiong, LU Jing
    2001, (2):  287-292. 
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    A variety of water quality parameters were monitored in enclosures for the polyculture of penaeid shrimp with tilapia and constricted tagelus.The result showed that the environment of the polyculture systems was better than that of monoculture one. The fluctuation of DO in the water of polyculture enclosures was less violent,and their lowest values were obviously higher than those in monoculture ones.The value of COD and the number of bacteria in the water of polyculture enclosures were significantly lower than those in monoculture ones(t-test,α<0.05),showing that the amount of organic matter in the water of polyculture systems was less than that in monoculture one. The biomass of plankton and the concentration of chlorophyll-a in the polyculture enclosures were also lower,showing that the suppression of the filtering animals to the plankton was obvious.The accumulation of N and P in the sediment of polyculture enclosures was 39.76% and 51.26%,lower than those of monoculture ones, respectively;and the number of bacteria in the sediment was 7.63% lower.Therefore,it is obvious that closed culture system can greatly decrease the effluent to the coastal waters caused by the pond culture industry,and decrease the pollution to the coastal waters.
    Maintenance ration and conversion efficiency of Hyporhamphus sajori
    GUO Xuewu, TANG Qisheng
    2001, (2):  293-295. 
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    The maintenance ration and conversion efficiency of Japanese halfbeak,Hyporhamphus sajori were tested with enclosures installed in a shrimp raising pond.The results showed that there existed an evident relationship between daily ration(DR)and growth rate(GR) of the fish,GR=140.37DR-24.03.The conversion efficiency was 13.96% in biomass or 16.12% in energy.The maintenance ration was 17.12% and 20.39% of body weight in terms of growth rate and specific growth rate,respectively,indicating that it could be deduced from growth rate quite differently from that from specific growth rate in the same experiment.The abnormal growth rate appeared when daily ration was below 3.30% of body weight,implied that Japanese halfbeak may get other food resources besides supplied net zooplankton.
    Technique of implanting 17α-methyltestosterone to induce the sex reversal of Epinephelus malabaricus
    CHEN Guohua, ZHANG Ben
    2001, (2):  296-298. 
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    This paper discussed the method of implanting 17α-methyltestosterone to induce the sex reversal of Epinephelus malabaricus, which included chemical treatment, dosage and operating on the fish. After twice implanting of exogenous hormone, the mature females of 3 years old were transformed into functional males. Sperm could be squeezed from 58% of the fish on 139 days after operating,and from 100% on 301days. When the functional males were used for artificial breeding, the parent fish spawned in a natural way, and 71.03 million larvae were hatched in the two years of 1999～2000. The larvae were used for rearing of fish fry, from which normally growing young fish was get.It is believed that the method of implanting exogenous hormone to induce the sex reversal of E.malabaricus is easy and stable, which can satisfy the requirement of artificial breeding in factories.
    Effect of silver carp stocking and fertilization on plankton community in enclosures in saline-alkaline ponds
    ZHAO Wen, DONG Shuanglin, ZHANG Zhaoqi, LI Deshang
    2001, (2):  299-303. 
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    The effect of silver carp (Hypophthalmichthys molitrix) stocking and fertilization on plankton community of enclosures ecosystem in saline-alkaline ponds were studied.After stocking silver carp in enclosures,the abundance,chlorophyll-a content and primary productivity of phytoplankton increased,and the biomass of phytoplankton was mainly composed by small species,such as diatom and green algae.Moreover,Euglnophyta and Chrysophyta were also sub-dominant species.The biomass of zooplankton decreased with fish stocking,and that of Cladocera was greater in control than in fish-culture enclosures.Zooplankton community was dominated by larger species such as Daphnia carinata in control enclosures.Fertilization,especially applying inorganic fertilizer,significantly increased the abundance and primay productivity of phytoplankton and the biomass of zooplankton.Although the biomass of plankton in the enclosures applied organic fertilizer was greater than that of control enclosures,the primary productivity and chlorophyll-a content of phytoplankton,the diversity index of plankton,and the P/R ratio were very low,and thus,silver carp grew slowly.The effect of filter feeding fish and applying fertilizer on the structure of plankton community was also discussed.
    Forest soil seed bank and natural regeneration
    YANG Yuejun, SUN Xangyang, WANG Paoping
    2001, (2):  304-308. 
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    The characteristics of temporal dynamics and spatial distribution of forest soil seed bank and their effects on natural regeneration were reviewed in this paper.The density of the seed bank of forest soil,which is affected by the types and ages of forest,is lower than that of cultivated land and grassplot,and can vary widely.The extent to which the composition of forest soil seed bank is influenced by its counterpart plantation depends on the stages of succession.The dynamics of forest soil seed bank is the combined effect of periodical and random factors.It is suggested that forest soil seed bank is the material base of forest regeneration,and the configuration and function of forest soil seed bank would influence the ability and the direction of natural forest regeneration.According to the characteristics of forest soil seed bank and obstructive factors influencing regeneration,some artificial measures can be adopted to accelerate natural regeneration.Studies on the forest soil seed bank should focus on the application of basic theories of disturbed ecology,and regard the reconstruction of degenerative ecosystem and the succession of populations in the ecotone as the main contents to study.As for the research method,it is advisable to employ long-term and located observations.
    Coarse woody debris and its function in forest ecosystem
    HOU Ping, PAN Cunde
    2001, (2):  309-314. 
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    Coarse woody debris (CWD) is an important structural and functional element in forest ecosystem.In this paper,the definition,dynamics,and role of CWD in a forest ecosystem were overviewed.CWD include all woody debris above and under the ground with a diameters ≥2.5cm,and mainly comes from the dead trees resulted from competition and disturbances.The biomass of CWD changes like“U”form along with the development of a forest community.The decay rate of CWD is determined by the compound course of the respiration and natural fragmentation.Insects and microorganisms play an important role in the course.CWD basically has two functions in an ecosystem.One is as the nutrition pool for some living creatures,and the other is that the large CWD can form some special habitats for animals and plants.Conclusively these two functions are helpful to reserve the biodiversity and the integrity of ecological process in a natural ecosystem.Gaps are formed while dead trees falling down,and all gaps in a forest succeed one another randomly in the development of a forest ecosystem,which pushes the inner circulation of the forest.Because of the vital roles of CWD in a forest ecosystem,much more attention should be paid in the management of forest ecosystem.
    Landscape changes of ecotone of temperate and sub-tropical zone and its ecological importance
    HOU Xiangyang
    2001, (2):  315-318. 
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    The change process of ecotone of temperate and subtropical zone and its effect on development, transformation and permeation of chinese agriculture and techniques were discussed in this paper from the viewpoint of landscape ecology. In historical time, the boundary of the ecotone changed northward and southward as climate changed, which changed southward 1～2 latitude in cold period and northward 1～2 latitude in warm period. The ecotone had an obvious environment diversity and strong sensibility, and played important role as a landscape conduit and barrier in aspects of chinese agricultural heterogeneous permeation and heterogeneity creation of agricultural techniques and cultures.
    Community characteristics of benthonic animals and its relationship to environmental factors in the Nanhu Lake, Changchun
    SUN Gang, SHENG Lianxi, LI Mingquan
    2001, (2):  319-320. 
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    There are only 21 species of benthonic animals in the Nanhu Lake,Changchun.The dominant species in the benthos community are obvious,and the individual quantity of Limnodrilus hoffmeisteri,Branchiura sowerbyi,and Tendipus plumosus accounts for 87% of the total individual quantity of all benthonic animals.It indicates that the water in the Nanhu Lake is suffering serious organic pollution,and belongs to an eutrophic lake.The peak values of benthos biomass and energy are found in July(48 23gWW·m-2and 241 16kJ·m-2respectively),while the maximum individual quantity is appeared in May(401ind·m-2).The distribution of Oligochaeta and aquatic insects has a significant positive correlation to organic content in the sediment(α<0 05).The community structure of benthonic animals reflects adequately the feature of the Nanhu Lake as an eutrophic lake in temperate zone.