Table of Content

25 January 1991, Volume 2 Issue 1

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Articles

Dynamic studies on regenerated seedlings of evergreen broadleaf forest in Jinggangshan region

Xie Fan, Wang Suzhen

1991, 2(1):  1-7. 

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In this paper, the distribution and ecological factors of regenerated seedlings of evergreen broadleaf forest are studied, and the seedling population and floristic features are analyzed. It revealed the possibility of restoration and development of evergreen broadleaf forest, which is mainly composed by tropic-subtropic floristic components in Jinggangshan region.

Effect analysis of release cutting for young growth of artificial Korean pine forest

Li Junqing, Yehchu Wang

1991, 2(1):  8-13. 

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Release cutting of an artificial Korean pine forest can remove all or 50% broadleaved trees over the canopy. The half-released stand is characterized by fast growth and high stand stocking. Its leaf area index, leaf area density and forest productivity are respectively 1.3, 0.8 and 1.3 times larger, solar radiation absorption is 100.3×10⁶J/m² more, and solar energy utilization rate is 0.06% higher than those of all-released one, Its nutrient accumulation rate is also larger. For young forest, half-release cutting is benefit to the formation of vertical stand structure, full utilization of environmental resources, decrease of competition and enhance of forest productivity.

A computer simulation of stemflow process

Wang Bennan, Pei Tiefan

1991, 2(1):  14-22. 

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In this paper, the continucus course of stemflow was dispersed through system analysis. After that, the program was composed, and the behaviour of stemflow process was simulated by computer. It makes us out of trouble to solve differential equation and obtain satisfactory results. This paper supplied a new method for continuous system and extended the concept of system and:\PDF\.pdfalysis.

Salt ecology of main plant communities of halophyte community complex in Keerqin Sandy Land

Xu Lan, Nan Yinhao

1991, 2(1):  23-31. 

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The effect of soil salinity on formation of halophyte community complex and its species compositions, patterns of horizontal distribution and species diversity in Keerqin Sandy Land of Northeast China was studied. The constancy of total contents of potassium sodium, calcium and magnesium, and variation regularity of sodium content in a species were explained. Based on sodium content and composition proportion of potassium, sodium, calcium and magnesium in a plant, adapted patterns of plant to saline-alkali soil and their divided method were proposed. According to the method, meadow plants in studied area could be divided into four patterns: Na>K>Ca>Mg type; K>Na>Ca, Mg type; K>Na, Ca, Mg type; K>Ca, Mg>Na type.

Integrated management of grassland rodent pest in Panpo area

Jing Zengchun, Fan Naichang, Zhou Wenyang, Bian Jianghui

1991, 2(1):  32-38. 

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This paper deals with efficient control and management of plateau zckor(Myospalax baileyi) and plateau pika (Ochatona curzoniae), the important rodent pests at heavy degenerative Kobresia bimilis grassland in the alpine meadow. The work was carried out at Fengxiakou, Menyuan county of Qinghai province from 1986 to 1989. In the meantime, an integrated management area about 800ha was built and a series of treatments including chemical control, oversowing grasses, fencing, graze and weed control etc. was practiced. Experimental results show that the poisoned efficiency of 0.075% Disphaeinoe-Na and 0.6% Gophacide grain baits were 85.1% and 77.3% for plateau zokor and 96.92% and 99.78% for plateau pika respectively. Oversowing, fencing, graze control etc. were organically combined after controlling the rodent pests. The vegetation of grassland was recovered and its productivity was raised at the integrated management in short period. According to determination, the biomass of forage grass increased 1.91 times at first year and 9.11 times at second year.

Optimum time and concentration of insecticide application to control paddy stem borer (Tryporyza incertulas)

Zhang Wenqing, Gu Dexiang, Zhou Zhiming

1991, 2(1):  39-47. 

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Optimum time and concentration of insecticide application depend on many factors including pest population dynamics, crop susceptibility to damage, crop yield in unit area, unit price of production, degradation rate of insectioide and its efficiency, and weather、The marginal analysis method is applied to develop a system model for determining the optimum time and concentration of insecticide application. The system model consists of four submodels: 1) population dynamic model; 2) yield loss forecasting model; 3) insecticide degradation model; and 4) insecticide efficiency model. Moreover, a weighted factor reflecting rice susceptibility to damage of paddy stem borer is introduced. By maximizing a function, the optimum time and concentration of insecticide application can be obtained.

Study on poplar canker caused by Botryodiplodia populea ZKZhong: biological characteristics of pathogen, pattern of disease incidence and fungicide selection

Zhong Zhaokang, Zhao Min

1991, 2(1):  48-51. 

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Experimental results show that the suitable growth temperature of Botryodiplodia populea Z.K.Zhong is 20—25℃, the suitable pHis 6—7, and potato dextrost agar and malt agai media are suitable for its growth. The bark produces disease spot during the second and last ten days of April, and the conididia appear in the first ten days of May. The conididia gradually mature, split and spill over the conididia after the second ten days of May. The fungus overwinters in the bark with mycelium. Through the fungicide selection in the laboratory, the biological fungicide 660Bshows the best result for controlling the pathogen.

An ecotoxicological study on chironomid larvae and tubificid worms

Cai Xiaoming

1991, 2(1):  52-57. 

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This paper deals with the ecotoxicology of floatation agent Petassium n-butyl xanthat (PNX) to Chironomus plumosus and Limnodrilus hoffmeisteri. The results show that PNXin various concentrations show a consistant toxicity to the selected chironomid larvae and tubifieid. The 24h-LC₅₀ of C.Plumosus is 256.2 ppm and that of L.hoffmeisteri is 25.8ppm. Ecological factors as temperature, pHand salinity may markedly modify the acute toxic effect of PNXto tubifieids. An objective symptom of the two species is successfully proposed in testing.

Enzymological diagnoses of soil pollution by heavy metals: influence of Cd, Cu, Pb and As in purple soil on dehydrogenase of rice roots

Wu Jiayan, Xia Zenglu, Ba Yin, Li Senzhao

1991, 2(1):  58-62. 

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In this paper, the influence of different concentrations of Cd, Cu, Pb and As on dehydrogenase of rice roots in acid purple soil and limy purple soil was studied. It shows that dehydrogenase undergoes the inhibition and produces the resistance under the influence of heavy metals in soil. When the concentrations are relatively low, the influence of Cd, Cu, Pb and As to enzymatic activities can reflect the difference of soil type. Based on the turning point of inhibition and resistance peak of dehydrogenase, critical concentration of Cd, Cu, Pb and As in two kinds of purple soil is defined.

A preliminary study of attaching organisms on artificial reef in Daya Bay

Li Chuanyan, Huang Zongguo, Zheng Chengxing, Lin Sheng, Wang Jianjun, Yan Songkai

1991, 2(1):  63-69. 

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From August 1988 tc July 1989, attaching organisms in the fish reef area of Daya Bay were investigated. 79 species were recorded. About 82.7% of these are bait organisms of fish and shrimps in the fish reef area, including35 species of nonshelled and 32 species of shelled bait organisms. 17.3% of the species are not bait organisms. The attaching organisms in the fish reef area were numerous in species, large in biomass and grew rapidly. Half a year after the reefs were cast, they were 100% covered by the organisms, with the thickness 30mm and the biomass reaching 17.487 kg/m², The reproduction and attachment of attaching organisms in the reef area occurred all the four seasons of the year. The major attaching period was July, August and September, which can be selected as the best period for the cast of the reefs.

Water-saving agriculture and its physio-ecological bases

Shan Lun, Xu Mvng

1991, 2(1):  70-76. 

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The key problem needed to be solved in water saving agriculture is to increase the utilization efficiency of rainfall and irrigation. Recent experiments and practices reveal that great petential exists in raising field productivity through the approaches of increasing plant water use efficiency (WUE); the aims of high yield and low water consumption may be achieved simultaneously. In order to reach this goal, it is necessary to study and determine the permitting degree of plant water deficit. Each physiological process of plants has different sensitivity to water deficit. On the basis of our experiment and other researchers' work, the effect of water deficit on physiological processes which are closely related to crcp yield is in the following sequence: Growth-Transpiration-Photosynthesis-Translocation. Under certain conditions, the limited water deficit does not influence the grain yield, and the WUEcan be increased remarkably.

Impacts of three gorge project on agricultural ecosystem in Changjiang River Basin

Xu Qi

1991, 2(1):  77-84. 

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In this paper, the impacts of three gorge project on agricultural ecosystem in Changjiang River Basin were studled. These impacts fall into two categories. The first is suddenchanging impact including land inundating, people migration and increasing pressure on alway-weakened ecosystem and environment of reservoir area. The second is slow-changing impact with variation of hydrological condition, namely, increasing trend of potential gleization and bogging of paddy field in middle and lower reaches and salinization in delta area. To improve ecosystem and land bearing capability in Changjiang River Basin, some measures should be taken such as closing hillsides to facilitate forestation, preserving water and soil, reasonably arranging the proportion of land for crops and forest, strengthening amelioration of water and soil and preventing soil gleization, bogging and salinization.

Ecologv of Trichoderma and its application in biocontrol of plant disease

Zhang Shuocheng

1991, 2(1):  85-88. 

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This paper reviews some advances in biological and ecological researches of Trichoderma, and summarizes their application in soil, above-ground plant and integrated plant disease management, and commercial industrial production and securities as to vertebrate. Finally, some items for its further research, especially for applicable one in China was put forward.

Preliminary study on tree death of Korean pine-deciduous mixed forest of Changbai Mountain

Chen Hua, Xu Zhenbang

1991, 2(1):  89-91. 

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By investigating dead trees in4 ha permanent plots of Korean pine-deciduous mixed forest of Changbai Mountain, the tree mortality of Korean pine-deciduous mixed forest is low. It ranges from 0.3 tree·ha^-1·yr^-1 or 0.46 t·ha^-1·yr^-1 to 2.1 tree·ha^-1·yr^-1 or 1.23 t·ha^-1yr^-1. Wind is one of the major causes of tree death. The influence of disturbances (windfall, fire, insects, diseases, human activities, ect.) on Korean pine-deciduous mixed forest during past survey period is iimited. This forest ecosystem is in steady state.

Integral analytic technique research for suspended solids in land treatment system

Song Yufang, Zai Lin, Guo Lixin

1991, 2(1):  92-95. 

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Based on the characteristics of land treatment system purifying organic pollutants, and absorping nutrient, physical, chemical and biological characteristics of suspended solids in influent and effluent of land treatment system and in control water bodies were analyzed qualitatively and quantitavely by means of integral analytic technique. The difference of suspended solids between influent and effluent of land treatment system is clarified, and thus, the scientific basis for purification of suspended solids by land treatment system has been provided.