Table of Content

25 November 1998, Volume 9 Issue 6

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Articles

Formation mechanism of flooding and waterlogging disasters in region of Dongting Lake and their ecological reducing strategies and watershed management

Wang Kelin, Zhang Chunhua, Yi Aijun

1998, 9(6):  561-568. 

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Dongting Lake, a lake-reservoir characterized by flood course, receives water from rivers of Xiangjiang, Zishui, Yuanshui, Lishui and a part of Yangtze, and inflows into Yangtze River.In the development of the Dongting Lake region, the environmental management and ecological construction were neglected, the relationships between mankind and land and between mankind and lake were not soundly harmonized, the soil and water erosion in the upper and middle reaches of Yangtze River was aggravated, the sediment deposited in lakes, the lands at lake marshes were excessively reclaimed, and the cropping system at high water level zones was irrational.Consequently, the flood-regulating capacity was descending, the level and the duration of flooding were raised and prolonged, the protective embankments were high and fields were low, the flooding happened out the protective embankments and the fields waterlogged, the frequency of disasters enlarged, and the damage increased.To prevent and fight against floods, the protective embankments were constructed more and more highly, emerging vicious circle of “flood raising embankment leveling-flood re-raising-embankment re leveling”, making flood level go up and flood duration lengthen, and decreasing the draining ability of waterlogged fields.According to the principle of harmonious development between mankind and nature, six ecological strategies for reducing disasters and watershed management were put forward.

Biomass and net productivity of Quercus variabilis forest in Baotianman Natural Reserve

Liu Yucui, Wu Mingzuo, Guo Zongmin, Jiang Youxu, Liu Shirong

1998, 9(6):  569-574. 

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Determinations of a 45 years old natural secondary Quercus variabilis forest in Baotianman Natural Reserve in Neixiang County, He'nan Province show that its biomass was 167.6417t·hm^-2, 94.75% of which was the tree layer, and its net productivity was 8.4880t·hm^-2 ·yr^-1, in which, the tree layer was 7.9254t·hm^-2 ·yr^-1 .The average relative growth rate of biomass was 0.041.The biomass and net productivity of shrub layer were 0.0694t·hm^-2 and 0.0456t·hm^-2 ·yr^-1, respectively, while those of herb layer were 0.1041t·hm^-2 and 0.0908t·hm^-2 ·yr^-1, respectively.The standing storage of litter was 8.63t·hm^-2, and the yearly litter was 5.0395t·hm^-2 ·yr^-1, which were respectively 5.15% of total biomass and 59.37% of total net productivity.The net production had a positive correlation with leaf area index(LAI)and leaf biomass, but a negative correlation with leaf efficiency.

Distribution pattern of tree populations in tropical forest and comparison of its study methods

Wang Zhengfeng, An Shuqing, Zhu Xuelei, David G. Campell, Yang Xiaobo

1998, 9(6):  575-580. 

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By means of individual in-plot-based variance/mean ratio and Morisita's dispersion index, and individual distance based modified nearest neighbor method and combined count distance -analysis, the distribution patterns of eight major species in mountainous tropical rain forest in Diaolou Mountain of Hainan were investigated.The results show that the distributions of all eight species are clumped or random, and that among the four methods, the combined count distance analysis is the best.

Larch litter and soil fertility

Chen Lixin, Chen Xiangwei, Duan Wenbiao

1998, 9(6):  581-586. 

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The larch plantations at Maoershan Mt.Experimental Forest Farm in eastern mountainous region of northeastern China were studied to characterize the dynamics of soil fertility under the same thinning larch stand at different age stages and the difference of soil physical and chemical properties between the thinning and non-thinning stands, according to the litter amount, the nutrient return from it, the standing litter, as well as the soil physical and chemical properties.The results show that the litter amount and its nutrient return presented an increasing tendency with increased stand ages.After thinning, the introduction of broad leaf trees into the larch plantation made the litter component structure changed, the litter decomposition rate gradually increased, the nutrient material release and return from litter sped up, the contradiction between litter accumulation and decomposition alleviated and the soil fertility of larch plantation increased.On the average, the contents of organic matter, total Nand total P₂O₅ were respectively increased by 352.00%, 225.53% and 34.96% within15 years.The soil physical and chemical properties of larch plantation after thinning were improved in varying degrees.

Restoration of degraded ecosystem and agroforestry in tropics and subtropics

Peng Shaolin

1998, 9(6):  587-591. 

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The tropics and subtropics in China are the regions most seriously stressed by human population and environment.The destruction of natural ecosystems and the increasing area of degraded ecosystems are the key factors limiting the development of agriculture.A long-term study on restoration ecology shows that integrated management has a great ecological, economic and social effect on the restoration and reconstruction of degraded ecosystems.The forest-fruit-herbage-grazing-fish complex ecosystem stemmed from the practice of restoration and reconstruction of degraded ecosystems is an agroforestry model with high yield, high quality and high efficiency in hilly areas, and an efficient approach to enhance the development of local agricultural economy.

Accumulation and cycling of Ca and Mg in Castanopsis eyrei community in Wuyishan Mountains

Li Zhenji, Lin Yiming, Yang Zhiwei, Lin Peng

1998, 9(6):  592-596. 

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Studies on a 51 years old Castanopsis eyrei community in Wuyishan Mountains show that the standing had a storage of 1029.96kg·hm^-2 Ca and 231.34kg·hm^-2 Mg, 801.40kg·hm^-2 Ca and 159.68kg·hm^-2 Mg in aboveground part, and 228.56kg·hm^-2 Ca and 71.66kg·hm^-2 Mg in underground part.The annual uptake was 63.17kg·hm^-2 Ca and 18.68kg·hm^-2 Mg, annual retention was 31.77kg·hm^-2 Ca and 11.41kg·hm^-2 Mg, and annual return was 31.40 kg·hm^-2 Ca and 7.27kg·hm^-2 Mg.The enrichment ratios of Ca and Mg were 1.66 and 2.14, respectively.

Models of soil saturated infiltration coefficient and effective porosity in forest catchment

Li Jinzhong, Pei Tiefan, Li Xiaoyan, Niu Lihua

1998, 9(6):  597-602. 

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The saturated infiltration coefficient and effective porosity of two undisturbed soils taken from typical original forests in Changbai Mountain Natural Reserve were determined, and the mathematical models of them in different soil depth were established by regressive analysis, which are K_s(z)=K₀-f₁ lna₂z and ω(z)=ω₀-f₂ lna₂z .Acomparison of these logarithmic models with the Beven's exponential models shows that the formers are more accurate and more reasonable for forest catchment.

Characteristics of field water cycling in semiarid area of western Liaoning Ⅰ. Status of field water supply

Wang Shixin, Cui Jianbo, Zhuang Jiping

1998, 9(6):  603-607. 

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Studies on the status of field water supply in semiarid area of western Liaoning Province showed that the water consumption by crops mainly came from rainfall in growing season and soil water storage.An insufficient rainfall, and especially, a serious water shortage in early growing season was the important cause for the decrease of crop yield.Water supply from rainfall accounted for 75.6% of water comsumption, and that from soil water storage was up to 24.4%.There was a linear relationship between water consumption by crops and rainfall in growing season.

Infection difference of wheat varieties to Rhizoctonia cerealis and relationship between incidence and severity

Tan Genjia, Ding Kejian, Zhang Chenglin, Shen Changqing, Chen Li

1998, 9(6):  608-612. 

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By means of artificial inoculation, the infection difference of 6 wheat varieties to wheat sharp eyespot disease (Rhizoctonia cerealis )was compared.The disease incidence of varieties at their seedling stage could not reflect the difference of infection among them, and it was available to use disease index to compare the infection difference at their late milking stage.It was considered that the growth stage of host affected the relationship between incidence and severity.The regression analysis shows that the classification based on disease index in internal and external stems could decrease the errors of field investigation, and save time and manpower.

Influence of natural enemies on populations of wheat aphid and greenbug

Zou Yunding, Bi Shoudong, Meng Qinglei, Geng Jiguang, Chen Gaochao, Wang Gongming, Li Jialin

1998, 9(6):  613-616. 

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After a systematic investigation on the populations of wheat aphids, greenbugs and their natural enemies during 1993～1996, the grey association analysis was made and showed that Propylaca japonica, Aphididae and Syrphidae were the natural enemies most greatly influenced the population of wheat aphid, while Erigonidium graminicola influenced the population of greenbug most greatly, and Propylaca japonica secondly.

Fluctuation of Bacillus licheniformis in micro-ecosystem

Hu Shangqin, Yuan Yuan

1998, 9(6):  617-620. 

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Investigation of the fluctuation of Bacillus licheniformis in micro-ecosystem with different inoculation culture methods shows that the bacteria can rapidly grow in the micro-ecosystem of healthy human body, and its amount can be kept in1.49×10⁸～1.83×10⁸g^-1 for a long period of time, and maintains 1.27×10⁷～1.51×10⁷g^-1 after 30 days.The bacteria grows slowly in the micro-ecosystem of patient, and its amount reaches a highest with 1.40×10⁸～1.67×10⁸g^-1, and maintains 1.15×10⁷～1.31×10⁷g^-1 after 30 days.In a man made simulated micro-ecosystem with pH 5.0～9.0, the amount of the bacteria is 3.05×10⁸ and 3.42×10⁸ml^-1 in mediums of homogenized food and of beef extract and peptone, respectively.

Ecological rehabilitation of drastically disturbed land at large opencut coal mine in loess area

Bai Zhongke, Wang Wenying, Li Jinchuan, Lu Chongen

1998, 9(6):  621-626. 

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With the combination of investigation, analogy, simulation, field test and demonstration, the characteristics of land disturbance and the suitable techniques for ecological rehabilitation at Pingshuo Antaibao Opencut Coal Mine were studied from 1991 to 1995.The original geological strata was substituted by a disorder derelict layer of rocks and loess with 100～150m height, resulting in the formation of typical artificial loose piled landforms, namely dumps.The original topographic appearance was substituted by terraced slopes, resulting in severe uneven subsidence during 5～10 years and instability of steep slopes.The original surface soil was substituted by loess typed parent material and stone shaped materials, resulting in soil bulk density >1.6g·cm^-3, resistance coefficient to plant roots 30～60kg·cm^-3, and organic matter content < 4.0 g·kg^-1 .After the original vegetation destroyed, it was very difficult to restore the original vegetation, resulting in soil erosion index >15000t·km^-2 ·yr^-1, 33% greater than that of original topography.The suitable technological systems for ecological rehabilitation include five engineering and three biological reclamation techniques.

Damage effect of monocrotophos on Platymonas spⅠ. Active oxygen in Platymonas spcells

Tang Xuexi, Yan Tingjin, Li Yongqi

1998, 9(6):  627-630. 

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Studies on the toxicity effect of monocrotophos on Platymonas sp.cells show that with increasing concentration of monocrotophos culture medium, the content of active oxygen in Platymonas sp.cells increased obviously, and correspondingly, that of malondialdehyde(MDA), peroxidation product of membrane lipid, and membrane permeability also increased.At the meanwhile, the activity of peroxidase(POD)and superoxide dismutase(SOD), two key enzymes for eliminating active oxygen, decreased gradually.These results indicate that under monocrotophos stress, the decline of PODand SODactivities broke the normal balance between production and eliminating of active oxygen, making active oxygen excessive and accumulated.The excessive active oxygen resulted in the aggravation of lipid peroxidation and the increase of membrane permeability, and therefore, the damage of Platymonas sp.appeared.

Damage effect of monocrotophos on Platymonas sp Ⅱ Relationship between chlorophyll-adegradation and active oxygen

Tang Xuexi, Yan Tingjin, Li Yongqi, Huang Jian

1998, 9(6):  631-634. 

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Under monocrotophos toxicity stress, the degradation of chlorophyll-a in Platymonas sp.cells aggravated, and its content decreased gradually with increasing stress intensity.The content of chloropphyll a was negatively correlated with those of active oxygen (O₂^-)and malondialdehyde (MDA)and the leaking rate of electrolytes, but positively with the activities of superoxide dismutases (SOD)and peroxidase (POD).The results indicate that under monocrotophos stress, the degradation of chlorophyll-a in Platymonas sp.cells was obviously correlated with the damage of active oxygen.

Bio-indication of bryophytes to environmental pollution in Anshan city

Cao Tong, Lu Yong, Wu Yuhuan, Xie Wei

1998, 9(6):  635-639. 

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By means of ecological survey and laboratory analysis, a comprehensive study on species number, distribution, index of atmospheric purity (IAP), content of Pb, Zn, Cu, Cd, total Spollutants in bryophytes, and their relationships with environmental pollution at five monitoring sites of Anshan city were carried out.In the seriously polluted region, including Anshan Steel & Iron Company, the species number of bryophytes was less than five; the IAPvalue was smaller than five; the pollutant content (mg·kg^-1 )in bryophytes was as follows: Pb(112～149), Zn(401～477), Cu(35.8～38.5), Cd(2.45～3.53), S(2200～3100).In the polluted region, including Lishan Park and Eryijiu Park, the species number of bryophytes ranged from 15 to 30; IAPvalue ranged from 5 to 25; the pollutant content was as follows: Pb(31.2～44.6), Zn(120～199), Cu(9.40～17.6), Cd(1.02～2.42), S(1400～2600).In the basically unpolluted region, including Lieshi Lingyuan and Qianshan, the species number of bryophytes was more than40; IAPvalue was larger than30; the pollutant content was as follows: Pb(15.4～25.6), Zn(84.3～135), Cu(5.24～11.5), Cd(0.64～1.99), S(800～2100).

Regulation of polycyclic aromatic hydrocarbons biodegradation in contaminated soil

Sun Tieheng, Song Yufang, Xu Huaxia, Wang Hongyan

1998, 9(6):  640-644. 

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Using temperature, moisture, surfactant TW-80 and C◇N◇Pratio as regulation factors, the biodegradation of ploycyclic aromatic hydrocarbons (PAHs)was carried out with an experimental period of 150 days.The results indicate that the degradation rate of PAHs reached 44.5～74.6% and 70.4～93.7% after 30 and 60 days, respectively.The optimum conditions for degradation during these periods were: temperature 40℃, moisture 25%, C◇N◇Pratio 120◇10◇1, and TW-80 concentration 200～500mg·kg^-1 .At the end of this experiment, the degradation rate of PAHs was up to 91.2～99.8%, with an optimum condition of temperature 40℃, and moisture 15%.The discrimination of Rvalue indicates that the influence of the four regulation factors on the degradation rate of PAHs varied with time.Temperature had a significant influence on the degradation of PAHs, and surfactants had a regulating role on the biodegradation of PAHs in soil.

Artificial neural network evaluation of lake eutrophication

Lu Wenxi, Zhu Tingcheng

1998, 9(6):  645-650. 

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Taking chemical oxygen demand, total nitrogen, total phosphorus and transparency as artificial neural network evaluation parameters and after repeated attempts.the four-layer structural Error Back Propagation Network(EBPN)was established to evaluate lake eutrophication.There are four neural units in input layer, four in both hidden layers, and one in output layer.Taking the eutrophication evaluation criterion of Taihu Lake as sample pattern, the network was trained in the light of learning rule of EBPN.After 37684 tries, the network reached the convergence standard given in advance, enabling it to possess the function of distinguishing the degree of lake eutrophication.This network was used to evaluate the eutrophication degree of 17 lakes in China.Its operation process was simple and convenient, and the results accorded with reality, showing that the approach has a series of advantages.

Theory and methodology of spatial heterogeneity quantification

Li Habin, Wang Zhengquan, Wang Qingcheng

1998, 9(6):  651-657. 

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In this paper, semivariogram was used to quantify the spatial heterogeneity in landscape.It was suggested that spatial characteristics and spatial comparison were the main aspects of spatial heterogeneity quantification.For spatial characteristics, the authors emphatically discussed how to use semivariogram to decompose spatial heterogeneity into quantifiable components, to determine the degrees of spatial heterogeneity, and to detect the scale at which spatial heterogeneity changes.For spatial comparison, the authors expounded how to statistically test the parameters of semivariograms to compare the spatial heterogeneity between same variable at two sites or different variables at same site, and put forward the standardized semivariograms to compare the spatial heterogeneity with different variables at the same site.The introduced theory and methodology were examined by the example of spatial heterogeneity of forest types and soil types in landscape of broadleaf Korean pine forests.

Modelings of terrestrial carbon cycling

Wang Yexu, Zhao Shidong

1998, 9(6):  658-664. 

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Terrestrial carbon cycling is one of the important components in the research of global change, and simulation modeling is a necessary method in understanding the carbon cycling in terrestrial ecosystem.The key processes in the modeling of carbon cycling include the response and feedback of the structure, function, composition and distribution of terrestrial ecosystem to climate change, elevated CO₂ concentration and human induced land use/cover change.Biogeographical and biogeochemical model are the two kinds of models in modeling carbon cycling, which differentiate in the way of model establishment, character and domain of model application.The developmental direction of carbon cycling modeling is to combine the elements of both kinds of models toward the formulation of global dynamic model of carbon cycling.

Development patterns of eco agriculture in immigrant settlement region of the Three Gorge reservoir area

Wu Gang, Su Ruiping

1998, 9(6):  665-668. 

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The agro land distribution, exploitation mode, existing problems, and development patterns of eco agriculture in the Three-Gorge reservoir area were discussed.There existed problems such as soil fertility degradation, poor productivity in crop land, frequent natural disasters and environmental deterioration in all exploited agro-lands.From the viewpoint of harmonizing mankind and nature, following suggestions were proposed: establishing development patterns of agroforestry complex ecosystem, tree food and oil, agroforestry-animal husbandry, and agroforestry animal husbandry-fishery.

Degradation process of red soil and its niche

Xie Zhengmiao, Lu Jun, Yu Jinyan, Huang Changyong

1998, 9(6):  669-672. 

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The biological characteristics in degradation and remediation of red soil as well as its relationships with eco environmental conditions were discussed by using niche concept.With biological cycles as the focal point, the development feature of red soil niche was analysed, and the rules and descriptive methods for degradation and restoration of red soil ecosystems were investigated to establish the methods and indicators for evaluating the degradation of red soils.