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Table of Content

    25 May 1998, Volume 9 Issue 3
    Articles
    Leaf area index and biomass productivity of mid and short rotation poplar plantations for pulp timber
    Fang Shengzou, Xu Xizeng, Lu Shixing, Tang Luozhong, Cao Fuliang
    1998, 9(3):  225-230. 
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    The study shows that the leaf area index(LAI) of mid and short rotation poplar plantations for pulp timber was increased with increasing planting density and stand age. Among the 3 poplar clones tested, NL-80351 had the highest LAI, I-72 had the lowest one and I-69 was the intermediate. The relationship between LAIand sunlight penetration rate could be described by extinction equation modified by M.Monsi and T.Saeki, and the extinction coefficient was 0.818 . LAIhad a close relationship with aboveground annual net biomass production, which could be expressed by exponential function. There existed a great difference of biomass productivity and distribution pattern among stands with different clones and planting densities at 4 years old. The biomass productivity of the stand with 1111 stems·hm-2 was the highest, as 1.4 times as that with 500 stems·hm-2 . NL-80351 had the highest productivity, and I-72 was the lowest. The biomass accumulation trend of stem xylem, branch xylem and bark could be described by Richards model. In different planting densities, the economic biomass for chemical pulp timber was in order of 1111>833>625>500 stem·hm-2 at 4 years old. However, for groundwood pulp timber, it was in order of 500>625>833>1111 stems·hm-2 . Clone NL-80351 had the highest stand economic biomass for both chemical and groundwood pulp timbers, I-72 had the lowest, and I-69 was the intermediate.
    Techniques for protection forest system construction on saline-alkalized soil of Liaohe Delta
    Pan Wenli, Yu Lei
    1998, 9(3):  231-236. 
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    The practices of tree species selection, soil amelioration and afforestation engineering on saline alkalized soils of Liaohe Delta show that Populus liaoningensis, Populus zhonglinensis 46 and Populus popularis can be planted on main canals where soil salt content is lower than0.3%. After soil amelioration, Robinia pseudoacacia, Ulmus pumila can be planted on sea banks where soil salt content is 0.4%, Fraxinus velutina can be planted on both sides of oil-field roads where soil salt content is 0.52~0.73%, and Tamarix chinensis can be planted on prevent tide dikes where soil salt content is 0.9%.
    Water conservaion capacities of soils with major forest types in mountainous regions of east Liaoning Province
    Hao Zhanqing, Wang Lihua
    1998, 9(3):  237-241. 
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    With the concerns of water conservation by forest, soils with same aged five forest types in mountainous regions of east Liaoning were selected to test their water-holding capacity. The storage of litter under these forests ranged from 10.87 to 18.67t·hm-2, which was greater in coniferous than in broad-leaved forest. The amount of water-holding by litter was 37.11~ 57.65 t·hm-2, and had a positive relationship with the storage of litter. The water storage of all forest soils within the depth of 50cm was 817.7~937.6t·hm-2 . Natural Mongoilan oak forest soil had the best infiltration rate and the highest water conservation, followed by soils with broad-leaved mixed forest, Korean pine plantation, Changbai larch plantation and Chinese pine plantation. In general, natural broad-leaved forests had a higher water conservation than coniferous plantations.
    Variations of nutrient contents and its numerical classification among nitrogen-fixing and non-nitrogen-fixing tree species of north deciduous trees
    Li Peizhi, Wang Lihua, Xu Siming
    1998, 9(3):  242-246. 
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    Abstract Nitrogen fixing and non-nitrogen-fixing species of north deciduous trees were studied to characterize the variation of nutrient contents and its seasonal dynamics. The results showed that the content of Nand Mg in foliage was significantly different between nitrogen-fixing and non-nitrogen-fixing trees during fast growing to leaf fallen period. The reduction tendency of Nand Kcontents in N-fixing trees was much slower than that of non N-fixing trees, but the accumulation of other elements and ash was higher than that in non N-fixing trees. Based on F-test and T-test, elements N, P, Mg and Si were selected as variables for numerical classification, and N-fixing and non N-fixing tree species were divided successfully.
    Rhizospheric effect of organic material on heavy metals in coastal saline soil I Distribution of soil native zinc forms
    Xu Xingkai, Zhang Sujun, Wu Longhua, Chen Xin
    1998, 9(3):  247-253. 
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    This paper studied the distribution of native zinc forms in coastal saline paddy soils with different salt contents under drainage condition and after applying decomposed organic material. The results showed that waterlogging was beneficial to the transformation of soil native zinc forms to those less available to plant in some degrees, suggesting the reduction of soil available zinc. Different salt contents significantly affected the variations of Zn bound to amorphous iron oxide (AFeO-Zn), Zn bound to tight humus (TOM-Zn) and silicate mineral Zn (MIN-Zn). Planting rice without the application of organic material was conducive to the depletion of exchangeable Zn (EX-Zn) and MIN Zn and the enrichment of Zn bound to carbonate (CAB-Zn), Zn bound to manganese oxide (MnO-Zn) and AFeO-Zn in rhizospheric soil, and the stronger zinc transformations in contrast to non rhizospheric soil. This induced that in rhizospheric soil, available zinc was close to its critical value which was higher than that in non rhizospheric soil. Organic material improved the transformation of MIN-Zn in rice rhizospheric and non rhizospheric soils, especially in rhizospheric soil with low salt content. With the increase of organic material incorporated with the soils, the transformation of MIN-Zn, MnO-Zn and CAB-Zn to EX-Zn, TOM-Zn and AFeO-Zn was promoted in rice rhizospheric soils with different salt contents, particularly with low salt content.
    Mechanism of nutrient preservation and supply by soil and its regulation I. P-preservation and supply by brown earth type vegetable garden soil
    Chen Lijun, Zhang Xiulan, Zhou Likai
    1998, 9(3):  254-256. 
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    etermination of P-preservation and supply performances of 15 pairs of fertile and infertile brown earth type vegetable garden soils sampled from northern, central and southern Liaoning Province show that in most soil samples tested, fertile soils and their various particle sizes of microaggregates had a larger amount of total and desorbed Pand a higher rate of Pdesorption, but a smaller amount of adsorbed Pthan infertile soils and their corresponding particle sized of microaggregates. The microaggregates of <10μm had a more stronger ability of P-adsorption than those of >10μm in both fertile and infertile soils. The microaggregates of <10μm in test vegetable garden soils had a large potential of Psupply, and their Pdesorption rate was one order of magnitude higher than that of other agricultural soils.
    Allelopathy of Ageratum conyzoides Ⅱ. Releasing mode and activity of main allelochemicals
    Kong Chuihua, Xu Tao, Hu Fei
    1998, 9(3):  257-260. 
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    Studies on the allelopathy of volatile substances of Ageratum conyzoides, animportant weed in South China, show that the volatiles of its fresh leaves significantly inhibited the seedling growth of all test plants.By means of chromatography, precocene Ⅰ and Ⅱ were isolated and identified, accounting for 30.93% and 51.61% of the volatile oil, respectively. These two substances in aqueous extracts of the weed originated from its volatiles, indicating that volatilization was the main mode by which the weed released allelochemicals. The saturated aqueous solution of the isolated and purified precocene Ⅰ and Ⅱ also significantly inhibited the seedling growth of radish, tomato and ryegrass. Especially, precocene Ⅱ had so strong allelopathic activity that it could inhibit the seedling growth at low concentration of 25μg·ml-1 . The mixed solution of precocene Ⅰ and Ⅱ did not show a significantly increasing inhibition to plants, indicating that there was no synergistic effect between precocene Ⅰ and Ⅱ.
    Effect of maize plant on N2O emission from field
    Huang Guohong, Chen Guanxiong, Huang Bin, Wu Jie
    1998, 9(3):  261-264. 
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    Observation on N2O flux in maize field using closed chamber technique shows that maize plant had a significant influence on N2O emission from maize soil system. The N2O emission from maize soil was greater than that from soil without maize. In addition, the roots of maize plant could obviously promote N2O emission from soil, especially in its later growing period. N2O emission after applying urea was 3.3kg·hm-2 from sowing to the end of the year, and 0.69kg·hm-2 of it came from maize plant, which accunted for 17.3% of total N2O emission.
    Plasticity of clonal modules of Leymus chinensis in response to different environments
    Yang Chi, Yang Li
    1998, 9(3):  265-268. 
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    Observations on the growth and differentiation of Leymus chinensis growing in greenhouse under controlled temperature and light intensity show that there was a significant plasticity for the growth of clonal modules. Lower temperature in a long period shading significantly inhibited the differentiation of rhizome and ramet modules (P<0.05), but did not affect tillering. Such an ecological adaptation would benefit Leymus chinensis to adapt to environmental changes.
    Isozymes of different geographic populations of Leymus chinensis
    Wang Min, Qian Ji, Zheng Shizhang
    1998, 9(3):  269-272. 
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    Six isozymes of Leymus chinensis from desert, typical, marsh and saline-alkali grasslands stretching across the Inner Mongolia to Jilin Province of China were studied. Cluster classification indicates that there existed a certain intraspecific differentiation of isozymes of L. chinensis in different geographic habitats, which was affected by comprehensive effects of many environmental factors, and internally related to the cold-resistance of the grass.
    Fuzzy comprehensive decision-making for resistance of wheat varieties to Macrosiphum avenae
    Hou Youming, Shen Baocheng
    1998, 9(3):  273-276. 
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    The resistance indexes of 50 wheat varieties to Macrosiphum avenae were applied to carry out the fuzzy statistical regression analysis. The fuzzy subordinate function of such resistance indexes as the quantity of aphid natural infection to wheat varieties, the accumulated rate of aphid survivals, the period of average development, the reproduction rate, the intrinsic increase rate(rm) and the harm-resistance of wheat varieties were set up, and the fuzzy comprehensive decision making models of resistance were established. The result indicates that fuzzy comprehensive decision model Vhad a high precision and much information holding.
    Interactive effect between Nilaparvata lugens and Sogatella furcifera nymphae
    Wang Rongfu, Zou Yunding, Cheng Xianian
    1998, 9(3):  277-280. 
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    Nylon net method was used to study the interactive effect between Nilaparvata lugens and Sogatella furcifera nymphae. The result shows that an interactive process was existed in different degrees between these two kinds of nympha. The expression of biological characteristics of the two planthoppers, such as emergence, sex, wing form, female's body length and weight, was affected in some degrees by the existence of each other. With an increasing proportion of N. lugens, the expression mentioned above of S. furcifera became more obvious, and vice versa, that of N. lugens was little. The effect of interspecific density was far greater than that of intraspecies, indicating that there existed a difference to the interspecific reaction between the biological characteristics of the two planthoppers.
    Ecological analysis of helminth population and community in goats body in Datian county of Fujian Province
    Wang Shoukun, Guo Guowei
    1998, 9(3):  281-285. 
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    Thirteen species of helminths, including6 trematoda, 1 cestoda and 6 nematoda, were collected from 30 goats. The total infection rate was 100%, and the mean infection intensity of the helminths was 646. Among the 13 species studied, Paramphistomum cervi had the highest total infection rate and mean infection intensity. The goats were infected by 1 to 8 helminth species which were all aggregated. There were eight dominant species in the helminth community. The infection rate and the density of the helminths had no correlation with the sex and the age of the goats. Interspecific association analysis showed that there were affinities for seven species pairs, and significant positrve and negative associations for two and three species pairs of the helminths, respectively.
    Effects of illumination, moisture and medium on oospore production of Phytophthora boehmeriae
    Gao Zhimou, Zheng Xiaobo, Lu Jiayun
    1998, 9(3):  286-290. 
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    The effects of illumination, moisture and medium on the oospore production (OP) of Phytophthora boehmeriae were studied in vitro by three factors randomized block design. The results indicated that the order of the effects of the test factors was medium>illumination>moisture, and the effects of both medium and illumination were significant at 0.01 level.On the media tested, the number of formed oospore was decreased with the order of SLAmedium (SLA)>lima bean agar medium (LBA)>V6 juice medium (V6A)>clarified V6 juice medium (V6B). Of the three illumination conditions designed, OPfrom the continuous darkness treatment was the highest, next was 12h illumination +12h darkness, and the lowest was from the continuous illumination treatment.The interactive effects of the three factors on OP were all significant at 0.01 level. Among different combinations of illumination, moisture and medium, OPfrom low moisture+continuous darkness+SLA was the highest, and that from low moisture +continuous illumination+V6Bwas the lowest.
    Growth, nodulation, N-fixing and seed production of Sesbania rostrata-Azorhizobium caulinodans symbiosis in South China
    Yang Zhongyi, Yuan Jiangang, Zhang Hongda
    1998, 9(3):  291-295. 
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    Studies on the growth, nodulation, N-fixing and seed production of Sesbania rostrata-Azorhizobium caulinodans symbiosis in South China show that the symbiosis could grow and nodulate well in this area. The dry matter production and nitrogen yield of 65 days-old S. rostrata grown in Zhanjiang were 28752 and 681kg·hm-2, while those of S.cannabina were 16520 and 352kg·hm-2, respectively. Mixed inoculating A. caulinodans strians AR111 and AR56 to S. rostrata was available in South China, and a 100% appearance of stem nodule was observed. The average number and fresh weight of stem nodules per plant were 182 and 1.2g, respectively, and the biomass of stem nodules accounted for 70% of the total biomass of stem and root nodules. The biomass of root nodules was slightly higher than that of S.cannabina. S. rostrata could normally blossom and bear fruits in South China, and its seed production with a planting population of 4×104 per hectare was 3200kg·hm-2 .
    Effect of vegetation on structure of soil microbial community
    Xia Beicheng, Zhou Jizhong, James, M. Tiedje
    1998, 9(3):  296-300. 
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    he relationships of different soils and vegetations with the structure and diversity of soil microbial community were studied. Vegetation made soil microbial species more abundant, and microbial community diversity more higher. There were no obvious dominant populations in soil microbial community, and the interspecific competition was feeble. The methods of molecular biology in the studies of soil microbial community were also introduced in this paper.
    Feeding effect of yeast and yeast alga mixture on Brachionus calyciflorus
    Wang Jinqiu, Li Deshang
    1998, 9(3):  301-304. 
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    Feeding experiments were conducted to search after the optimum density and relative effeciency of two kinds of yeast Saccharomyces cerevisiae and S. carlsbergensis and their mixture with alga (Chlorella pyrenoidosa) as the food of rotifer (Brachionus calyciflorus) .The results showed that the optimum density of S. cerevisiae and S. carlsbergensis was 10×106 and 5×106 cells·ml-1, respectively.The population density and instantaneous growth rate of the rotifer fed with S. cerevisiae and S. carlsbergensis were 40.2 and 26.6%, and 85.5 and 76.6%, respectively of those fed with alga.The feeding effect of yeast-alga mixture in a proper proportion was equal or superior to that of alga.
    Sensitivity of prawn to organophosphorus pesticides at its different development stages
    Ru Shaoguo, Li Yongqi, Jiang Ming
    1998, 9(3):  305-308. 
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    The 24h L C50of parathion, isofenphos methy, monocrotophos and dichlorvos for Penaeus chinensis at its nauplis, zoaea, mysis and postlarvae stages is respectively 6.0, 4.0, 3.8 and 18×10-3 mg·L-1 ;8.0, 3.5, 3.5 and 3.0×10-3 mg·L-1 ;24, 24, 24 and 0.9mg·L-1 and 48×10-3, 48×10-3, 48×10-3 and 48×10-3 mg·L-1 ;and that of parathion for Penaeus vannamri at its same stages is 8.6, 8.2, 8.0 and 2.0×10-3 mg·L-1 respectively. The results show that the tolerance of prawn to thiono form organophosphorus pesticide is stronger at its early development stage than at other stages, but its sensitivity to oxo form organophosphours pesticide is almost the same at its all development stages.
    Acute toxicity of Cu2+ to Rana chensinensis tadpole
    Wang Shoubing, Guo Rui, Qu Yunfang, Jing Zuoqin, Jiang Chaoguang, Wu Qianhong
    1998, 9(3):  309-312. 
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    The acute toxicity of Cu2+ to Rana chensinensis tadpole was determined under various water temperature. The results showed that, at 9~13, 18 and 24℃, its 96h LC50for 10 days old tadpole was 5.01, 3.80 and 2.99mg·L-1, respectively. The lethal concentration, was 4.0, 2.5 and 1.6mg·L-1, and the no observed effect concentration(NOEC) in96hours was 2.5, 1.6 and 1.0mg·L-1, respectively. The 96h LC50 for 20 days old tadpole was 2.17mg·L-1 at 18℃.
    Degradation of p-chloroaniline(PCA) in packed-bed bioreactor
    Wan Dengbang, Hui Yang, Chen Yunxia, Qiu Changqiang
    1998, 9(3):  313-317. 
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    With p-chloroaniline(PCA) as a selected substrate, the mixed microorganisms assimilating it as the sole source of carbon and nitrogen were obtained by acclimation technique from the enriched cultural products of degraded p dichlorobenzen(p-DCB). The mixed microorganisms immobilized in a packed-bed reactor were used to degrade PCA. In the packed-bed bioreactor, the biodegradation of PCAfollowed the Logistic equation, q = qmax /(1+eα-βUv ). The major kinetic parameters, Ks (half velocity constant) and qmax (maximum specific substrate degradation rate), were calculated. PCA was found to be degraded with a concomitant release of chloride ions into the substrate. Under the conditions of residence time of 3 hours and inlet stream at PCAconcentration of 360mg·L-1, the volumetric degradation rate of the substrate was 125mg·L-1·h-1, with removal efficiency of 91%.
    Transportation and transformation of14C-phenanthrene in a controlled nutrient solution lava wheat system
    Li Ying, Ou Ziqing, Sun Tieheng, Ayfer Yediler, Ines Conrad, Antonious Kettrup
    1998, 9(3):  318-322. 
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    With isotopic techniques, the transportation and transformation of 14C-phenanthrene in a controlled nutrient solution(NS)-lava wheat system was conducted. The results suggest that after applied for 24 days, 14C-phenanthrene in the controlled system degraded fast, and only 0.32 % of it remained in the plant, NSand lava. Most of 14C activity absorbed by plant was incorporated in plant tissues, and the remains existed prominantly as polar metabolites of phenanthrene.
    Hg harm on cell membrane of rape leaf and cell endogenous protection effect
    Ma Chengcang
    1998, 9(3):  323-326. 
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    In this paper, the harm effect of different HgCl2 concentrations on rape seedlings cultivated in sand for 50 days were studied.The results showed that the structure and function of leaf cell membrane, and the cell endogenous protection system had no measurable changes when the concentration of Hg was 0.5mg·L-1 .But, when the Hg concentration was higher than 1mg · L-1, the membrane lipid peroxidation was quickened, membrane structure was harmed, and the permeability of membrane was increased.At the concentration of 1~10mg Hg·L-1, the soluble protein content of leaf was increased, the activities of SOD, PODand CATwere accelerated in varying degrees, and the cells presented a positive endogenous protection effect.At 50mg Hg·L-1, the soluble protein content was decreased, the activities of SOD, PODand CATwent down steadily, and the positive protection effect disappeared.It is suggested that only within a certain limit, the cell endogenous protection system had a positive protection effect.
    Advances in ecotourism and its planning research
    Liu Jiaming
    1998, 9(3):  327-331. 
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    As an alternative form of tourism which is based on natural resources can promote the sustainable development, ecotourism has been gradually emphasized by the tourism policy makers, researchers and planners. This article deals with the definition of ecotourism and the assessment of its research progress about conceptual framework, functional zoning, planning model and management. The operational model and its implementation of ecotourism are put forward, and the significance of the surrounding context (the geographical background) and of the corporate identity is emphasized in the ecotourism planning.
    Problems needed attention on plant allelopathy research
    Kong Chuihua
    1998, 9(3):  332-336. 
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    Plant allelopathy is an active research area in recent years, but exists some problems and misunderstandings. Some important and confused issues on its basic definition and research content, releasing modes and research methods of allelochemicals, relationships of allelopathy with competition and environmental stress, and application potential of allelopathy were pointed out and discussed in this paper.