Table of Content

25 October 1991, Volume 2 Issue 4

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Articles

Canopy structure, light distribution and leaf biomass of tussah-feeding oak forest

Wen Shiyun, Yang Sihe, Yin Zhongfu, Wang Changje, Jiang Po, Huang Gang

1991, 2(4):  286-291. 

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Tussah-feeding oak forest is a unique coppiced forest ecosystem. In a long period of management, different canopy forms are artificially established. There practically exist three types of canopy forms. Comparative studies are conducted in canopy structure, light distribution within crown and leaf biomass for three oak species. The results show that among the three types of canopy forms, form A (the "Stair" form) has the advantages in higher leaf area index, more reasonable of leaf distribution pattern and the highest leaf biomass. The other two types have no significant difference in leaf biomass. But form B (the "Tree" form) is better than form C ("Shrub" form) for its larger crown, lower coefficent, of light extinction and better light environment within crown.

Effect of defoliation on growth and fruiting of ragweed

Guan Guangqing, Li Shude, Gao Dongchang, Zhai Qiang, Wan Fanghao, Wang Ren, Luo Wanqiu

1991, 2(4):  292-297. 

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Field experiments show that the plant height of ragweed untreated reaches to 223.3 cm, while the average plant height is respectively 212.1 and 184.0cm after single and multiple treatment with defoliation. Plants with six times defoliation died when grew to 130cm in height. In control, the number of fruit-bearing branches is 14.9. With defoliation at early vegetative growing stages, the formation of branches is obviously restricted; whereas defoliation at later, the growth of lateral branches is stimulated. The influence of cutting leaves on the numbers of floret and branch is basically consistent. For the plants untreated, the number of seeds is 1,873.2, and that of treated plants is obviously decreased. When treated in vegetative growing stages, the number of seeds reduces to 40—70%, and after treated for six times, the seed reduction rate is 100%.

Study on the response of photo-sensitive genic male-sterile rice to temperature and light

Wu Xiaojin, Yin Huaqi

1991, 2(4):  298-303. 

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W₆₁₅₄,S, Annong S-1 and Hengnong S-1 were selected as tested materials and method of seeding by stages was taken to study. Aseries of concepts of "critical low temperature", "critical high temperature" and "transitional temperature" were put forward in this paper. The CLTand CHTfor W₆₁₅₄Sand Annong S-1 were 23℃ and 25℃, and 23.5℃, and 27℃ for Hengnong S-1. It was considered that 1) the response of different PGMRs to temperature and light varies; 2) perhaps it is more suitable to use the name of "ecological factor——sensitive genie male-sterile rice" instead of "PGMR"; 3) the PGMRcould be employed in production.

Small scale agroecological regionalization: a case study of the Second Branch of853 State Farm in Sanjiang Plain of Northeastern China

Zheng Xunhua, Zeng Zhaoshun, Wen Dazhong, Ding Oingtang

1991, 2(4):  304-311. 

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In this paper, the agrcecological regionalization of the Second Branch of 853 State Farm in Sanjiang Plain of Northeast China was studied. Based on the natural conditions of the Farm, major indiceses of the regionalization were selected through the Quantification Mathod I, which are soil types, situations of potential drought and water logging, thinkness of albic horizon and landforms. According to their relative importance, the order of these indices was determined. The special maps for each index were overlaid to determine the basic units of the regionalization. With the first important index, agro-eco-sections were made up; with the second important index, agro-eco-sections were divided into agro-eco-sites; and with the third and forth important indices, agroeco-sites were divided into agro-eco-types.

Cationic form of natural zeolite and their agricultural suitability

Shi Yi, Zou Bangji, Dang Lianchao, Zheng Qiaoying

1991, 2(4):  312-315. 

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Natural zeolites with favourable properties of ion exchange and adsorption have received increasing attention in agriculture application. But negative effects may be obtained of applying them without considering their special characters. Our experiments indicate that the cationic form of natural zeolites with higher content exchangeable Na⁺ could greatly influence the growth of crops after their interaction with soil and fertilizer. For this reason, the agricultural suitability of natural zeolites should be re-evaluated.

Evaluation on environmental effect of the urease inhibitor hydroquinone

Zhao Xiaoyan, Zhou Likai, Li Ronghua, Xie Chongge, Li Shuding

1991, 2(4):  316-322. 

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Based on the simulation study, pot experiment and field experiment with labelled and unlabelled hydroquinone and consulting foreign literatures, this paper discussed the direction in which hydroquinone has gone, the eff ects of hydroquinone on soil biological activity and its environmental effect when applicated with minor amount over long period of time. It is concluded that minor amount of hydroquinone entered into soil with hydroquinone containing urea fertilizer will not accumulate in soil and plant, and not enterinto underground water and atmosphere. In soil, hydroquinone will be involved in the formation of humic substances or photooxidated,ozonated and biodegrated, forming dibasic acids through the break of benzene ring. In plant, it will be assimilated by the conjugation of glucoside. It has a promoting or inhibitory effect on the activity of soil enzymes at the early stage of application but assuaged or disappeared with time. Therefore, hydroquinone used as an urease inhibitor will not induce the pollution of environment and the poising of food chain.

Citrus whitefly population dynamics and effect of pesticide on it

Zhang Yanling, Tao Zhengliang, Luo Zhiyi

1991, 2(4):  323-328. 

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On Changxing island of Shanghai, whitefly occurs yearly three generations, with the 4th instar nymph overwintering there. In each stage, the death rate of eggs and 4th instar nymph is highest, and that of 2nd instar nymph is lowest. The survival curve of population is subjected to the weibull model type Ⅲ. The field population dynamics characterised by age structure reflects the growth and decline of whitefly in field and the effect of pesticide on them. The population dynamics of citrus whitefly on privet tree is analysed as well, and the roles of citrus whitefly served as alternate foods ofpredacity mite (Amblyseius eharai) are also discussed.

A Study on the interactions of microsporidia-asian corn borer-corn in univoltine ACB area of Northeastern China

Wen Jinzeng, Huang Hong, Wang Wancheng, Meng Xiangwei, Wang Xiaoqiang, Li Fengshan

1991, 2(4):  329-333. 

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Field experiment results show that ACBs acquired Nosema furnacalis infection by vertical transmission were infected heavier than those by horizontal transmission. In the former case, borer population declined significantly at harvest time, but not in the latter case, though the incidence was as high as 91.5—95.5%. During overwintered period, the population of infected larvae declined. Sampling and examination of corn borers from overwintered cornstalks at three localities showed that the prevalence of Nosema was usually high, its increased mortality was more pronounced at prepupal stage. The paiasitism of larvae by Nosema and Beauveria bassiana resulted in obvious reduction in ACB population, but about 50% infected adults still emerged from the survivors as the new infectious source. Experimented result on the effect of ACBdensity on yield loss show that yield losses in the two of three test varieties were calculated as 1.32% and 1.39% for every additional borer respectively, but in the third variety, yield losses among different infected levels were not statistically significant. The variety showed a high tolerance to the ACB. The borer tolerant variety is advantageous to the circulation of infectious source and thus there is a coordinated relationship between microspridia and borer tolerant variety. It is suggested that borer tolerant varieties, microsporidia, together with other ecologioical factors, may compose a control system to reduce the ACBpopulation density to an economically tolerable level.

Influence of warming climate on agro-ecological environment in Northeastern China and its countermeasure

Bi Bojun

1991, 2(4):  334-338. 

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Agroecological environment in Northeastern China could be greatly by affected the warming climate. Its variation tendency will be: 1) heat condition becoming favourable to crop growth, 2) growing period be lengthened, 3) frequency of cold damages be decreased, 4) period of snow accumulation be shortened, 5) humid condition becoming unfavourable to crop growth, and 6) drought frequency and evaporation be increased. If average temperature raises 2℃ caused by the warming climate, grain yield in Northeastern China will increase 36% or so, and agricultural zones will move greatly toward north. Thus, corresponding countermeasures must be adopted,

Study on ecological distribution of protease-producing bacteria in zonal soils

Zhang Tingzhou, Ma Xiaohang, Xu Guanghui

1991, 2(4):  339-343. 

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From north China to south China, 32 samples of various types of soil were collected and main ecological factors which might affect the distribution of protease-producing bacteria were studied. Through the study, 491 strains of bacteria were obtained and purified. All of them were systematically observed and their protease-producing activity were half-quantitatively examined. The probable high yielding strains were chosen out and cultured by shaking-flask liquid fermentation method and their protease activity was quantitatively measured. Based on the different protease activity and distribution of bacteria, the relationship between ecological condition and distribution of protease-producing bacteria was studied and following conclusion was obtained: the ecological distribution of protease-producing bacteria has some positive relation with the amounts of soil organic matter and nitrogen.

An approach to the enactment of soil-environmental standards(Hg, Cd, Pb and As) in China

Wu Yanyu, Zhou Qixing, Tian Junliang

1991, 2(4):  344-349. 

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According to the current situation of researches on soil-environmental quality standards at home and abroad, and on the basis of foundations and principles proposed for enacting soil-environmental standards, soil-environmental quality standards of Hg, Cd, Pb and As were explored. The research indicates that the functional land use in China includes: (1) natural or clean areas; (2) agricultural and pastoral areas; (3) forested areas; and (4) urban and waste disposal areas. The corresponding standards are 0.10, 0.20, 0.50, 1.00mg/kg for Hg; 0.15, 0.30, 0.50, 1.00mg/kg for Cd; 30, 60, 100, 300mg/kg for Pb; and 15, 2027, 30(except sandy soil areas) mg/kg for As.

Wastewater treatment by simulated artificial wetlands

Yang Changfeng, Huang Ganquan, Song Wenchu, Li Xiongwen, Xie Qiming

1991, 2(4):  350-354. 

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Using simulated artificial wetlands for wastewater treatment, the purification dynamic and optimum detention time in the system were studied, and the effects of pH, Eh and temperature on purification were discussed. The mean removal efficiencies in5 days were BOD₅ 94.8%, TN 93.0%, TP95.0% and NH₃-N 99.5%. When the Pb and Cd concentrations were under 2500mg/Land 250mg/Lrespectively, the removal efficiencies of Pb and Cd were more than99.9%, and the process was basically completed in3 hours. Even if the Pb content is 2.86g/kg and Cd 0.29g/kg in substrate, the removal efficiencies of Pb and Cd were still 96.2—98.5%.

Influence of phosphorus on algae growth and sewage purification

Gao Yurong, Huang Yuyao, Cao Hong, Chen Yanmei

1991, 2(4):  355-360. 

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An experiment on the influence of phosphorus in raw sewage on algae growth and sewage purification was carried out in modelling stabilization pond system in laboratory. Results indicate that when TNconcentrations are all kept at 20 mg/Lin raw sewage and TPare changed from 1.25, 2.50, 5.00 to 10.00mg/L, the removal rate of TN, BOD₅ and LASare decreased with increasing TPconcentration, but the removal rate of TPpresents an opposite tendency. The ratio of N/P=20/2.50mg/Lis the better concentration and ratio for sewage purification than others. This result is correlated with the net oxygen production of algae. There are different species composition of algae existed in different N/Psystems. When the ratio of N/Pis changed from 20/1.25, 20/2.5, 20/5 to 20/10 mg/L, the percentage of green algae is decreased with increasing TPconcentration, but blue algae presents an opposite tendency which may cause high levels of algae density, biomass, oxygen consumption, pHvalue and low rate of purification.

Quantitative evaluation of land ecological environment in six cities of Hangzhou Bay and its significance in territory programming

Wu Cifang, Tang Gennian

1991, 2(4):  361-366. 

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Based on the analysis, investigation and Delphi's determination, seven factors of population density of land, population loading per unit cultivated land area, residential and industrial using land area, industrial economic density of land, land area with slop of more than25 degrees, land area per unit growing stock of forest and area of no ensuring stable yields through drought/flood are chosen. Using three methods of weight value accumulation, cluster analysis and fuzzy comprehensive estimation, the ecological environments in six cities of Hangzhou Bay are analyzed and evaluated comprehensively. Results can be applied in practice of territory programming. This test has reference significance to probe into the theory and method of land ecological evaluation.

Application of economical ideas and methods in behavioural ecology

Shang Yuchang

1991, 2(4):  367-372. 

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Animal's behaviour can be reiewed as having eosts and benefits, and animals should be designed by natural selection to maximize net benefit. This economic idea can be used as a basis for formulating optimality models in behavioural ecology. When shore crabs are given a choice of different sized mussels, they prefer the size which gives them the highest rate of energy return. In order to calculate exactly how many different sizes should be eaten, it's need to develop an optimality model. Territorial behaviour should be favoured by selection whenever the benefits are greater than the costs. Optimal territorial size can be also predicted by building an economic model. The basic principle that animals minimize the risk of starvation can be applied to foraging decisions. Downy woodpeckers can use the gleaned information while foraging in order to maximize their food-intaking rate.

On establishment of ecology-economical type of the "Threc North" protection forest system

Gao Zhiyi

1991, 2(4):  373-378. 

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This paper outlined the "Threc, North" protection forest system, discribed the guiding ecology and economical line in establishment of shelter forest system, and further discussed the significance and foundation of renewing the concept of "froestry". The academic concept of ecology-economical type of shelter forest system (ESSFS) and its relation with the formation of regional artificial ecosystem are introduced. Taking a demonstration area of ESSFSin Xinshuihe basin on loess plateau as an example, the paper discussed the technical connotation, composition and ecology-eco nomical characteristics of ESSFSin hilly mountain areas. The author summarized some points of enlightenment from the practice of shelter forest project on the better establishment of shelter forest engineering in other regions.

Isolation and ecological characteristics of decolorizing bacteria from dyeing wastewater

Zhao Yinwei, Shen Jian, Zeng Su

1991, 2(4):  379-382. 

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In general, bacteria hardly adapt to printing and dyeing wastewater, as the contaminants changed frequently. 17 strains of bacteria growing well in complex and changeful printing and dyeing wastewater were isolated, and their ecological characteristics were studied. They can be applied to the process of microbial decolorizaton.