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Table of Content

    25 July 1999, Volume 10 Issue 4
    Articles
    Gap formation and its characteristics in south subtropical evergreen broadleaved forest
    Liu Jingyan, Wang Bosun, Zang Runguo
    1999, 10(4):  385-388. 
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    This paper analyzed the manners of gap formation and the characteristics of gaps in the south subtropical evergreen broadleaved forest in Heishiding Reserve of Guangdong Province. The results showed that the most popular manner of gap formation in the forest was stem breakage (51.86% of the total), and the second, uprooting(39.98%). Most gaps were formed by two trees, averaging 2.63 trees per gap. The size of most expanded gaps was in the range of 100~300m2, the gaps of 200~300m2 occupied the biggest percentage in area, and those of 100~200m2 occupied the biggest percentage in number. The size of most canopy gaps was under 100m2, the gaps of 50~100m2 had the biggest percentage in area, and those of <50m2 had the biggest percentage in number. Most of the gaps were formed 40 years ago, and less than10 years were the most. The diameter at breast height of most gap makers was 20~30cm,and their height were 20~30m. The average area of expanded gap and canopy gap formed by one gap maker was 72.94m2 and 25.06m2, respectively.
    Biomass and net productivity of Picea schrenkiana var tianshanica forest
    Wang Yan, Zhao Shidong
    1999, 10(4):  389-391. 
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    The measurement of the biomass and net productivity of spruce (Picea schrenkiana var. tianshanica) forest in Mulei County of Xinjiang showed that the total biomass was 216.170t·hm-2, and the net productivity was 12.634t·hm-2·yr-1. The biomass percentages of stem, twig, needle, fruit and root were 48.68%, 17.77%, 9.81%, 0.03% and 18.60%, respectively and the net production percentages of them were 31.49%, 1.20%, 12.70%, 0.46% and 26.87 %, respectively.
    Structural dynamics of Juglans mandshurica, fraxinus mandshurica and Phellodendron amurense Ⅱ Process of leaf birth and death
    Ye Wanhui
    1999, 10(4):  392-394. 
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    he analysis on the process of leaf birth and death of Juglans mandshurica, Fraxinus mandshurica and Phellodendron amurense shows that the birth of their leaves was a gradual process, with a duration of 40~60 days. The leaves born in different periods formed a distinct age class structure. The growth process of leaflet basically revealed an Stype curve. The death of leaves was distinguished into leaflet, with little litterfall and slow speed. Then, the compound leaves began to fall, and the quantity of defoliation increased and the speed quickened. The whole defoliation continued for 30~35 days. The process of leaflet fall was a Deevey Type Isurvival curve, and the compound leaves, a Type Ⅱ.
    Multidimensional time series analysis on tree growth
    Wu Chengzhen, Hong Wei
    1999, 10(4):  395-398. 
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    By the analysis of multidimensional time series, five important climatic factors were used as control factors in CARmodel to forecast the diameter growth of Chinese fir. This model could predict the diameter growth of Chinese fir one year in advance, and the accuracy of forecasting results was quite high. This method may be regarded as a new way for predicting tree growth.
    DCA ordination of ecological distribution of saprophytic bryophytes in forest ecosystems in Changbai Mountains
    Guo Shuiliang, Cao Tong
    1999, 10(4):  399-403. 
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    pplication of DCAto study the ecological distribution of saprophytic bryophytes in Changbai Mountains showed that there existed differences in the components of saprophytic bryophyte communities in Pinus koraiensis broad leaved mixed forest, dark conifer forest, and the transitive forest between Pinus koraiensis broad leaved mixed forest and dark conifer forest. In Pinus koraiensis broad leaved mixed forest, Plagiomnium cuspidatum, Thuidium philibertii and Brachythecium buchananii were the main saprophyte bryophytes. Plagiomnium cuspidatum, Trachycystis flagellaris, Thuidium cymbifolium, Callichladium haldanianum and Hylocomium splendens were the main saprophytic bryopytes in the transitive forest between Pinus koraiensis broad leaved forest and dark conifer forest. Whereas, Hylocomium splendens, Sanionia uncinata, Rhytidiadelphus triquetrus, Oncophorus wahlenbergii and Ptilium crist castrens were the main ones in dark conifer forest. The total coverage and species diversity of saprophytic bryophytes were the highest in dark conifer forest. Altitude and forest canopy density were the two important environmental factors influencing the distribution patterns of saprophytic bryophytes in the forest ecosystems in Changbai Mountains.
    Role of nitrogen fixing trees in mixed forest Ⅲ Leaf litter decomposition and its N release of nitrogen fixing tree species
    He Xingyuan, Zhao Shuqing, Yang Sihe, Tian Chunjie
    1999, 10(4):  404-406. 
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    Studies on the leaf litter decomposition and its N release of 11 N-fixing and non-N-fixing tree species showed that the biological decay coefficient of leaf litter, the dry weight loss of leaf litter during its decay, and the N release from the leaf litter of N-fixing tree species were 1.3, 1.5 and 8.2 times higher than those of non-N-fixing ones, respectively.
    Application of ectomycorrhizal fungi in Pinus taeda plantation forest
    Zhang Dinghua, Huang Jiabin, Sun Qinfu
    1999, 10(4):  407-410. 
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    Six years studies on the application of ectomycorrhizal fungi in Pinus taeda plantation forest show that after inoculation, all of the 12 supplied fungi strains could in various degrees form ectomycorrhizas on pine roots. Of the supplied fungi strains, Bolecinus pinetorum had the best effect on pine growth, whether for seedlings or after their planting, and more significantly in soils with low fertility.
    Evolution of moisture environment of small watershed in gully region of Loess Plateau
    Huang Mingbin, Kang Shaozhong, Li Yushan
    1999, 10(4):  411-414. 
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    Taken the Nanxiaohe watershed as a study case, the influence of engineering and biological measures for soil and water conservation and procedures for improving productivity level on the moisture environment was evaluated. During the past 50 years, the moisture environment of Nanxiaohe watershed was significantly changed. The total annual surface runoff decreased from 15.83mm before starting integrative controls to 3.66mm at present time, and would reduce to 2.86mm in the future 10 years. The plateau runoff increased, due to the increase of courtyard and road area and the improvement of building style, and the slope and gully runoff gradually decreased. Meanwhile, the increased productivity further reinforced the small cycle of water and weakened its big cycle, and changed the quantitative distribution of water balance elements in watershed.
    Distribution of zinc forms and its influence factors in calcareous purple soils
    Gao Meirong, Zhu Bo, Jiang Mingfu
    1999, 10(4):  415-418. 
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    In order to approach the mechanism of zinc deficiency in the calcareous purple soil widely distributed in hilly regions of central Sichuan Province, eight forms of zinc were determined from 30 samples by sequential chemical extraction method and the data were treated by optimum regression and correlation analyses. There were remarkable differences among all forms of zinc, which were influenced by soil pH, texture, organic matter and carbonates. The carbonates not only enhanced the adsorption of zinc by soil oxides and clay minerals, but also adsorbed and immobilized it (2.70% of total Zn) by themselves. Soil pHand organic matter were the major factors affecting available zinc.
    Transformation mechanism and availability of mutrients in albic soil plant system ⅡInorganic phosphorus transformation in albic soil
    Li Fayun, Gao Ziqin
    1999, 10(4):  419-422. 
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    Incubation test and microplot experiments were conducted to study the transformation of inorganic phosphorus in albic soil.The results show that most part of soil inorganic phosphate was transformed into iron and aluminum phosphates after a short period of incubation (24 hours and 8 davs,respectively),and aluminum phosphate was transformed into iron phosphate after 80 days of incubation.Calcium phosphate changed slightly throughout the whole period.Aclose relationship between inorganic phosphorus transformation and soil properties was found.The transformation process of inorganic phosphorus was changed by applying organic fertilizers,whose reaction with iron and aluminum oxides induced the formation of “organic matter iron phosphate” and “organic matter aluminum phosphate”complexes which can be easily uptaken by crop.
    Effect of organic material on transformation and translocafion of metal oxide in albic soil and their impacts on soil fertility
    Wu Longhua, Gao Ziqin
    1999, 10(4):  423-426. 
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    Soil column experiment showed that in albic soil,DTPA or organochelated Fe, Mn and Al were significantly increased when decayed alfalfa powder was added. Soil available Pwas also enhanced,mainly due to the increase of soil aluminum and iron combined P (P-Al and P-Fe).In albic layer,soil available Pand four forms of inorganic Pwere all significantly positively correlated to the amount of added alfalfa powder,while in surface layer, only available P,P-Al and P-Fe were significantly positively correlated to the dose of organic material. Soil available P,P-Al and P-Fe were significantly correlated to DTPA or organo chelated Fe,Mn.The difference was in surface layer,their relationships were negative,while in albic layer, they were positive.
    Mechanism of nutrient preservation and supply by soil and its regulation Ⅱ Binding status of humus in brown earth type vegetable garden soils and its role in fertility
    Chen Lijun, Zhou Likai
    1999, 10(4):  427-428. 
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    Studies on the storage of organic matter and the binding status of humus in 15 pairs of fertile and infertile brown earth type vegetable garden soils and their various fractions of microaggregates sampled from different regions of Liaoning province show that fertile soils and their various fractions of microaggregates had a larger amount of organic matter and various binding status of humus and a higher ratio of loosely bound humus vs. total organic matter, but a lower ratio of steady bound humus than infertile soil and their corresponding particle sized microaggregates. The ratio of tightly bound humus vs. total organic matter had a little difference. In both fertile and infertile soils, the smaller size of microaggregates had a larger amount of organic matter and various binding status of humus and a higher ratios of loosely and steady bound humus than the larger sizes of microaggregates, but the ratios of tightly bound humus reversed, indicating that the smaller and the larger sizes of microaggregates played different roles in soil fertility.
    Rhizospheric effect of organic material on heavy metals in coastal saline soil Ⅱ. Distribution of soil native ferric forms
    Xu Xingkai, Zhang Sujun, Wang Zijian
    1999, 10(4):  429-432. 
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    This paper studied the distribution of native ferric 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 increase of amorphous iron oxide (A-FeO), complexed Fe (Com-Fe), DTPA-extracted Fe and activity coefficient of iron oxide (ACIO) in saline soils tested whileas crystalline iron oxide (C-FeO) almost had no change, suggesting the transformation of soil other unknown ferric forms to C-FeO, and that Com-Fe and DTPA-extracted Fe in low saline soil increased more significantly than those in high saline soil. Planting rice without the application of organic material was beneficial to the enrichment of Com-Fe and DTPA-extracted Fe and the depletion of A-FeO and C-FeO in rhizospheric soil, and the lightly lower ACIO than that in non-rhizospheric soil. Organic material improved the transformation of native ferric forms to Com-Fe and A-FeO in rice rhizospheric and non-rhizospheric soils, particularly in rhizospheric soil with low salt content, and significantly increased DTPA-extracted Fe and ACIO in these soils.
    Experimental studies of farmland ecological engineering on controlling disasters of seawater intrusion in Laizhou Bay
    Qi Xinshan
    1999, 10(4):  433-436. 
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    In view of the serious situations of drought, water shortage, seawater intrusion and land productivity decline in Laizhou Bay area of China, exemplary experimental studies of farmland ecological engineering were carried out in Laizhou and Shouguang. The ecological engineering mainly included the techniques of the selection of improved varieties, crop structure adjustment, rotation and intercropping, plastic film covering, water saving irrigation, soil fertilization and crop tree intercropping, which gave a remarkable ecological and economical benefit. Based on this, the exemplary models on controlling the disaster of seawater intrusion and on realizing the sustainable development of agriculture were set up.
    Degradation mechanism of typical grassland in Inner Mongolia
    Wang Shiping, Li Yonghong
    1999, 10(4):  437-441. 
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    The experiment was conducted on the degraded grassland in Inner Mongolia dominated by Artemisia frigida and short grasses with given stocking rates for 6 years, to study the morphological responses of 9 major plant populations to grazing. The results show that the grasses with different life types and vegetative reproduction properties differed in responding strategies to stocking rates, which formed the basis for community succession at different stocking rates. The herbage with vegetative reproduction by stolons or of higher tillering, such as Artemisia frigida and Potentilla acaulis, were suitable for heavy grazing. Leymus chinense and Agropyron cristatum which are vegetative reproduction by rhizomes and tillering and Stipa krylovii were suitable for light grazing. Carex duriuscula with vegetative reproduction by rhizomes and tillering and Cleistogenes squarrosa were suitable for medium grazing. Melissitus ruthenica and Kochia prostata with branching reproduction were suitable for light grazing. The community composition changed with increasing stocking rate, and the proportion of short grasses in community gradually decreased. Consequently, the degraded grassland dominated by Artemisia frigida and short grasses ultimately converged to the degraded grassland dominated by Potentilla acaulis. Light grazing could maintain the existing state of grassland, or make it retrograde by increasing the proportion of grasses, which achieved the goal of utility typed improvement.
    β-diversity of grassland communities along gradient of grazing disturbance
    Yang Limin, Li Jiandong, Yang Yunfei
    1999, 10(4):  442-446. 
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    Grazing disturbs grassland environment through gnawing and treading of livestock, which changes species composition and population's dominant. This study showed that the species richness in communities gradually decreased with the aggravating of grazing intensity from saline moist meadows to typical steppe communities. The measurement of β diversity showed that on saline moist meadows, the intermediate disturbance of species change occurred during the course of light to moderate grazing stage, with a low stability during the whole grazing; while on meadow steppes and typical steppes, it occurred during the course of moderate to heavy grazing stage. Desert steppe showed a high stability throughout grazing system, and the species change from light to over grazing was only 1~3. The stability of grassland community diversity was as follows: desert steppe>typical steppe≥meadow steppe>saline-moist meadow.
    Effects of wheat varieties on main life parameters of wheat aphids
    Wu Junxiang, Jiang Jinhu, Shen Baocheng, Su Xiaoji
    1999, 10(4):  447-451. 
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    This paper deals with the effect of wheat varieties on main life parameters e.g., the survivals, growth and development, and reproduction of two wheat aphids Rhopalosiphum padi and Macrosiphum avenae, and analyzed the correlativity of experimental results in glasshouse and field. Ten wheat varieties were selected, which have been demonstrated the different resistance to wheat aphids in former field experiment. The results show that the resistance of these wheat varieties did not obviously affected the mortality of nymphal aphids, but significantly affected the development duration of nymphal aphids, and the longevity and fecundity of adults. The effect of various wheat varieties on the development duration of nymphal aphids of two species in glasshouse was correspondent with that in field. Therefore, the nymphal development duration could be used as one of the most important indexes identifying the anti aphid of wheat varieties. Moreover, the fecundity of R.padi adults in glasshouse was correspondent well with that in field.
    Dynamics of arthropod populations on different varieties of Nicotiana tabacum
    Wu Houzhang, Cheng Xianian, Zou Yunding
    1999, 10(4):  452-456. 
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    Investigations on the population fluctuation patterns of important arthropods on three Nicotiana tabacum production varieties Nc89, Nc82 and K326 were conducted in the suburbs of Hefei from May to July, 1998. In the investigated tobacco fields, araneae taxa were Linyphiidae, Lycosodae, Theriodiidae, Tetragnathidae, Thomisidae, Salticidae and Clubionidae, etc.. The major insect natural enemies were Aphidius gifuensis, Coccinellidae, Staphylinidae, Carabidae, Syrphas corallae and Orius miutus, and the major insect pests were Myzus persicae, Heliothis assulta, Dolycoris baccarum and Gryllus testaceus. The aphid population fluctuation showed two peaks, with the first one around 16 May and the second one from 13 to 21 June. The models of aphid population dynamics and the interreaction between Myzus persicae and Erigonidium graminicola were analysed. The mean seasonal number of Aphidius gifuensis population, and hence, that of total insect pests, were significantly higher on Nc89 than on Nc82 and K326. There was no significant difference in the mean seasonal number of other arthropods on different tobacco varieties.
    Damage of citrus leafminer to citrus and its economic threshold
    Wang Liande, You Minsheng, Wu Qing
    1999, 10(4):  457-460. 
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    The damage of citrus leafminer (Phyllocnistis citrella) to four citrus varieties (Xuegan, Rugan, Jiaogan, and Fujue) was investigated at citrus garden in Fuzhou suburbs from September 1993 to December 1994. Because the errors in economic threshold could be produced by different damage figures and annual fluctuation of citrus yield, the autumnal treetops were adopted as numerating units, and the determined twigs were rooundly cut. The photosynthesis intensity of leaves damaged by leafminer, the growth of the damaged autumnal treetops in current year and the vernal and autumnal treetops in second year, the fruit quality and quantity in second year, and the relationship between the damage degree of leaves and the density of leafminer population were studied. The results show that after damaged by leafminer, the leaves had certain compensation abilities in photosynthesis and tissue concrescence. According to the production level of citrus in Fuzhou in1994, the economic threshold on Xuegan was set at 1.21 larvae of first instar per tender leaf, which reduced the errors in economic threshold produced by annual fluctuation of citrus yield. Based on several ecological factors, e.g. citrus varieties, hydrothermic conditions in citrus garden, yield and natural enemies, a multi factor economic threshold model was established.
    Effectiveness of natural enemies on Spodoptera litura
    Jiang Jiexian, Liang Guangwen, Pang Xongfei
    1999, 10(4):  461-463. 
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    The 4th and 8th generation life tables were applied to evaluate the effectiveness of natural enemies on common cutworm (Spodoptera litura) population by exclusion index of population control (EIPC). The results showed that the predatory natural enemies of the 1st, 2nd and 3rd instar larvae were the important factor influencing the population dynamics of common cutworm. The EIPCvalues of the 4th and 8th generation common cutworm were 13.904 and 12.496 respectively, which means that the next generation of common cutworm population would increase 15.1206 and 74.678 times of current generation if the predators were excluded. The pathogenic microbes were another important factor affecting the 4th generation population, and its EIPCwas 2.4726.
    Relationship between native breeding pigs trait and ecological type in Anhui Province
    Chen Hongquan, Jiang Moyou
    1999, 10(4):  464-466. 
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    Studies on the relationship between the ecological conditions of Anhui Province and the trait of native breeding pigs show that from north to south, the upland area decreased from 54.3% to 1.9%, while forest area and grass land area increased from 5.6% and 3.0% to 62.4% and 15.8% respectively. The irrigated land was mainly distributed in Jianghuai hills(JH), and Yanjiang plain(YP), while waters were mainly distributed in Yanjiang plain. With decreasing latitude, the mean yearly temperature and precipitation gradually increased, and the feedstuff changed from intensive into green forage. Pig body size gradually decreased, and mean individual body weights at the age of 1 day and 20 days decreased from 1.02kg and 3.48kg to 0.73kg and 2.16kg respectively. The mean function teat number and litter size of sow in Wannan mountatinous(WM) were higher, but no obvious variation in other types. The daily gain and lean percentage decreased from 535.9g·d-1 and 55.3% to 361.1g·d-1 and 39.5% respectively, and fat thickness increased from 19.9mm to 39.3mm. The mean numbers of Ag NOR per cell for JH, YP and WM were 3.17, 3.61 and 3.68, and the genetic distances among them were 0.1176, 0.1404 and 0.0568 respectively.
    Metabolism of zinc from ZnMet by goats
    Li Lili, Zhang Bin, Huang Jianliang
    1999, 10(4):  467-470. 
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    An experiment was conducted to compare the metabolism of zinc from zinc methionine (ZnMet) chelate by 10 healthy goats which were divided into two groups fed with basal diet plus 65ZnMet and 65ZnSO4,respectively.The results showed that the 65Zn concentration in feces was lower in65ZnMet group than in65ZnSO4 group.The absorption of zinc from 65ZnMet was 49.12%,significantly (p<0.05). higher than that from 65ZnSO4(38.91%) The excretion of zinc came to a climax after 52 hours in 65ZnMet group,18 hours later than that in 65ZnSO4 group. The remaining rates of 65Zn in goat bodies were 40.38% in65ZnMet group and 29.52% in 65ZnSO4 group. There was no significant difference in remaining rates between the two groups after stopping 65Zn feed for 3 days. In whole experimental period and in both groups,the zinc content in unit gram of liver,spleen and pancreas was higher than that in other tissues and organs,and the lowest was found in unit gram of bone and hoof.
    Dynamics of soil microbial biomass and soil enzyme activity and their relationships during maize growth
    Shen Hong, Cao Zhihong, Xu Bensheng
    1999, 10(4):  471-474. 
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    The dynamics of soil microbial biomass Cand Nand of the activities of soil catalase, invertase, protease and urease, and their relationships during maize growth were studied. The microbial biomass Cand Nand the enzyme activities increased rapidly and gradually reached a maximum during the early and middle periods of maize growth, then decreased and gradually remained stable during the later period. The microbial biomass and the enzyme activities were the highest in straw plus urea treatment, compared with straw treatment, urea treatment and control. No relationships were observed between microbial biomass Cand Nand hydrolyzable nitrogen, active humus and pHduring the late period of maize growth, while the relationships between microbial biomass Cand Nand activities of catalase, protease and urease reached significant or extremely significant level during maize growth.
    Interactive effect of time temperature and time moisture on Beauveria bassiana conidia
    Wang Chengshu, Fan Meizhen, Li Zengzhi
    1999, 10(4):  475-477. 
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    The curve surfaces of time temperature mortality and time moisture mortality of Beauveria bassiana conidia were processed by complementary log log (CLL) model. Hosmer Lemoshow testing showed that the regression of obtained function was significant, and t test indicated that the parameters of the models reached significant level(P<0.0001). The comparisons of each correspondent LT 50 values in effective time zone showed that it was higher when estimated by single factor analysis than by CLLmodel at different bathing temperature, and at different moisture content, the values estimated by single factor analysis were higher at low moisture contents (RH<33%) or lower at high moisture contents (RH>44%). Comparing with the traditional analysis methods, CLLmodel could provide the information of functional effect affected by time, and of time effect affected by functional factors as well.
    Killing effect of soaking liquid of fresh Pterocarya stenoptera on Oncomelania hupensis
    Wang Wanxian, Yang Yi, Ke Wenshan, Liu Youqi, Ma Anning, Yang Wenye
    1999, 10(4):  478-480. 
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    With pentachlorophenol sodium and pure water as controls, the soaking liquids of the fresh roots, stem barks, and leaves of Pterocarya stenoptera were used to examine their killing effect on Oncomelania hupensis. The result shows that the soaking liquid at>5% concentrations could kill 20~100% bodies of Oncomelania hupensis. When treated for 240h., the mortality of O.hupensis was up to 93.5~100%. The soaking liquid of 2.5% fresh leaves of P.stenoptera mixed with 2.5% leaves of Sapium sebiferum, Taxodium ascendens or Cinnamomum camphora, or with the whole boby of Rumex japonicus or Artemisia apiacea, killed 96.7%, 93.3%, 80%, 100%, 86.7% bodies of O.hupensis, respectively, when O.hupensis was treated for 240h.
    Comprehensive benefits of land treatment eco engineering for wastewater —A case study on forest type slow filtration land treatment system in Huolinhe River
    Yang Cuifen, Sun Tieheng, Li Peijun
    1999, 10(4):  481-484. 
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    In order to scientifically and quantitatively evaluate the comprehensive benefits of land treatment eco engineering for wastewater,the index system and index weight of evaluation and the calculating methods for comprehensive benefits were provided through the analysis of horizon profile (AHP).Then,the AHPwas used to analyze and evaluate the comprehensive benefits of a forest type slow filtration land treatment system engineering in Huolinhe Region. The results indicated that the value of comprehensive benefits for this system was 0.64,which economically belongs to a middle grade ecosystem with a good benefit on both environmental and society.
    Effect of EDTA on toxicity and distribution of Cu in aquatic microcosm
    Zhang Yimin, Jin Hongjun
    1999, 10(4):  485-488. 
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    The effect of EDTA at different concentrations (0.0,1.0,8.0mg·L-1) on toxicity and distribution of Cu(2.0mg·L-1) in simulated aquatic microcosm was conducted. The results show that after adding Cu at concentration of 2.0mg·L-1, the time curves of population size, chlorophyll a concentration, and ratio of total primary production to total respiration of Daphnia magna were lower in treatment without EDTAthan in other treatments. The presence of EDTA decreased the toxicity of Cu to Daphnia magna and algae, and alleviated the influence of Cu on metabolic function of ecosystem, but changed the distribution of Cu in different apartments of the microcosm. The amount of Cu increased by 0.1~6.7% in water body, while decreased by 0.8~6.5% in sediment. In addition, the presence of EDTAaffected the Cu bioaccumulation by Daphnia magna and algae.
    Ingestion of copepods on Prorocentrum micans in seawater experimental enclosures
    Wang Yan, Zhang Hongyan
    1999, 10(4):  489-491. 
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    The ingestion rate of copepods, Schmackeria poplesia and Oithona sp. on Prorocentrum micans was studied in a seawater enclosure with serious water bloom of P.micans. The mean ingestion rate of copepods with a body length>125mm,which included adult and some copepodites of S.poplesia, on P.micans was 12140 cells·ind-1 ·d-1, while that of other copepods with a body length <125mm, which included some copepodites of S.poplesia and both adult and copepodites of Oithona sp., was only 1133 cells·ind-1 ·d-1.During experimental period, the concentration of P.micans in the enclosure was 850~16170 cells·ml-1, and the population specific growth rate of the algae ranged from -0.002 to 0.150. It is clear that the ingestion of copepods was not enough to inhibit the growth of P.micans population, if P.micans was in growth phase. Therefore, the copepods in enclosure could not prevent from occurrence or development of P.micans bloom.
    Benefit evaluation on water and soil conservation forest A review
    Shen Hui, Jiang Fengqi
    1999, 10(4):  492-496. 
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    Water and soil conservation forest is an important kind of protection forests, which has ecological, social and economic benefits.The evaluation on its comprehensive benefits is currently a significant topic, and the methodologies are quite different due to different interests.The evaluation process begins with constructing a set of complete index system and determining the weight of each index, then the benefits are calculated by appropriate mathematical methods, and last, the assessing models of evaluating comprehensive benefits are defined.Several representative evaluation methods and assessing models are appraised, and the problems and tendencies of research on benefit evaluation are pointed out in this paper.
    Air quality improvement and sulfur fertilizer requirement in agriculture
    Wang Qingren, Li Jiyun
    1999, 10(4):  497-500. 
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    This paper reviewed the physiological requirement of plants for sulfur and the source, composition and concentration of sulfur containing compounds in the air. It also discussed their supplementary effects to plant ecosystems, the plant's absorption and assimilation to the gaseous compounds and their suitable concentrations for plants. As the requirements of human's health and eco environment in recent years, many countries have started to control the emission rate of sulfur containing waste air by legislation, which, on the contrary, has frequently resulted in sulfur deficiency for crops. In some areas, sulfur is becoming one of the most important factors limiting the agricultural development. Therefore, sulfur requiring amount and expansion extent are increasingly enlarged in the global agriculture, and more work on the research and development of sulfur fertilizers should be conducted.
    Crop growth simulation model and its application
    Yang Jingping, Wang Zhaoqian
    1999, 10(4):  501-505. 
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    This paper reviewed the present situation of related study development of Crop Growth Simulation Model (CGSM), and its mechanism and role in agricultural production. The existing problems of the model in application and its developmental direction in future were also discussed.
    Microbial genetic adaptability to environment and molecular ecological efficiency of plasmid
    Zhang Suqin, Luo Ruxin
    1999, 10(4):  506-510. 
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    The genetic adaptability of microbes to environment is the mechanism of microbial evolution. There are complex signal networks between microbes and environmental factors to regulate the mutual adaptability of microbes and environmental novel signals (pollutants). The formation and the presence of plasmids make host cells obtain this adaptability. The wide spread of plasmids in natural environment results in species diversity. This paper reviewed the response of microbes to pollutants and the molecular ecological efficiency of plasmids.
    Relationship of litter decomposition and consumption with soil animals in Maoer Mountain forest
    Zhong Weiyan, Yin Xiuqin, Chen Peng
    1999, 10(4):  511-512. 
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    The study shows that in Maoer Mountain, the rates of litter decomposition and consumption were higher in pure Pinus koraiensis-forest than in P.koraiensis broad leaved mixed forest. In the course of litter decomposition and consumption, soil animals, and soil macrofauna in particular, played more important role than soil microbes. The seasonal variation curves of soil animal species and individuals were similar to those of litter decomposition and consumption rates, with the peaks in July, which indicated that the decomposition and consumption of litter was correlated with soil animals.