Table of Content

25 April 1990, Volume 1 Issue 2

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Articles

Researches on improving the quality of forest land and the productivity of artificial Cunninghamia lanceolata stands

Chen Chuying, Zhang Jiawu, Zhou Chonglian, Zheng Hongyuan

1990, 1(2):  97-106. 

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Artificial C. lanceolata stand dominates in the forest ecosystems of subtropical zone in China and occupies very important status in the production of timber. However , long term's practices and researches have manifested that, pure C. lanceolata plantations exha usted large amount of nutrients during the period of growth and development, and si multaniously, the amount of soil microbes declined year by year, the biochemical activity and oxidative-metabolic capacity got weaker, the degradation of forest land quality and productivity was brought about. Furthermore, repeatedly planting C. lanceolata trees in curred the land capability to decline gradually, and the toxic vanillin-like substances accumulated. Hence, the environment of soil became worse, and worse, and the produc tivity was cut down by mort than30 percent. Experiments confirmed that the mixed plantation of C. lanceolata and Michelia macclurei not only dispeled many defects of pure C. lanceolata stand, but also had better performances on ecological and economical effici ency. It is one critical way to solve the problems just related.

One-dimensional model of delayed surface runoff in litter layers of broad-leaved korean pine forest

Liu Jiagang, Pei Tiefan, Fan Shixiang, Han Shaowen, Niu Lihua

1990, 1(2):  107-113. 

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According to the mechanism of water flow and the experience, and based on the single-iactor simulation experiment of delayed surface runoff in litter layers with various slopes and water contents in the Forest Hydrology Simulation Laboratory two equations of delayed surface runoff were constructed.αH/αt=B-αF/αX , F=f(αH/αX, (H-H₀)sinA). These equations were solved numerically with the iteration method, and the solutions agree with the experimental data very well.

Study on dry resistance of seven young coniferous and broad-leaved trees with PV-technology

Tian Youliang, Guo Liansheng

1990, 1(2):  114-119. 

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In order to inquire into potential application of PV (Pressure-Volume) technique to research the dry resistance of tree and compare the differences between young and adult trees in this respect, the dry resistances of young trees of seven species including pinus sylyestris var. mongolica were investigated based on physioligical parameters of dry resistances of their adult trees. The parameters of water conditions in one-year branches of both young and adult trees were measured with PV-curves. They changed with the annual growing processes of the branches. It is relatively reliable and practical that the water parameter of either early stage of young branch growth or the full lignification stage of the branch are considered as the indicators of their dry resistances.The young trees have the less dry resistance than the adult ones during the early stage of young branch growth. There are almost no differences between young and adult trees after the full lignification of the branches.d:\PDF\.pdf

Effects of comprehensive reclamation of boggy bottomland on soil microbes and yield of soybean in Sanjiang Plain

Wang Shujin, Lin Jishang, Xue Delin, Xu Guangming, Tang Kehui, Hao Naibin, Ge Qiaoying, Guo Yu

1990, 1(2):  120-128. 

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The soybean yield has been increased to 1950—2100kg/ha from 982.5kg/ha since the co mprehersive reclamation carried out on the boggy bottom and in Sanjiang Plain in1986. The techniqnes of reclamation include:(1) Irrigation and water conservancy engineering; (2) Mechanical cultivation; (3) Biological techniques, especially the introduction of so ybean breed with high abilities of photosynthesis and N-fixation. The activities of Nfixation of Bradyrhizobium japonicum, Sinorhizobium fredii and other N₂-fixers and their populations sharply increased after the reclamation. Deep plough with machines benefits activities of the microbes and the development of root system and nodulation of soybean. More 3 good breeds of G. max with high photosynthesis rate and a strain of S. fredii, Sj8855, with high N₂-fixation and tolerence the boggy bottomland and pesticide have been developed and used.

"Three Materials" tramsformation and eco-agriculture

Hu Daize

1990, 1(2):  129-135. 

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Solar energy fixed in green plants, especially in crops, is the source and basis of agro eco-economic system. Ashare of the primary organic products is sold as commodity, a share is consumed by farmers themselves and the others become the carrier of energy and material currents transforming into secondary production. The transformation rate and economic benefit of the crop's by-products are different due to their various utilization ways. Forages, fertilizers and fuels are all necessary in primary production, secondary production and human life. The transformation ways and rates of the "Three Materials" should play a major role in adjusting the structure and function of agro-eco-economic system. In this paper, the major effects of "Three Materials" (3F) transformation are analysed. The technical line of increasing the transformation effect at a greater rate and improving the construction of eco-agriculture is put forward.Its technical key is to ex plore straw resources and saprophagous food Chains.

Study on the ecological way of preventing cucumber downy mildew: A report of a control experiment on the environmental temperature

Ma Shuqing, Liang Honghai, Ma Jixiang

1990, 1(2):  136-141. 

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Cucumber downy mildew is a rather serious plant disease damage in every place of world. The starting and prevailling of the disease relate closely to its environmental temperature. It can be prevented by proper high temperature condition, because the producing, growing and damaging of the disease spores can be inhibited by high temperature. The dates of starting and prevailling of the disease can be postponed and the damaging degree can be mitigated obviously by using an high temperature control way: raise air temperature in the plastic cucumber shed up to 40—47℃ by closing the door and air-inlet at about noon, last it more than two hours, and then, open the door and air-inlet for "change air" and do it every second day. This preventing way can make the cucumber production increased about 45 per cent and it is more efficent than others.

Adaptation of leaf mesophyll structure to environmental light condition and its effect on leaf photosynthesis

Chen Dexing, Wang Tianduo

1990, 1(2):  142-148. 

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In this paper the hypothesis that most structural features of leaf can be explained as the adaptation to maximise leaf photosynthesis capacity has been explored. The light envi ronment within leaf is described by the application of the K-M theory and a leaf photo synthesis model incorporating it was presented.Finally, the adaptation of mesophyll stru cture to environmental light condition to maximise leaf photosynthesis was demonstrated by applying optimization theory. Comparing the leaf photosynthesis with different ratios of palisade to spongy tissue showed that there is an optimal ratio (e.g.Kp = depth of pa lisade layer/depth of spongy layer = 0.6), which is very close to actual leaf structure (Table 2). It has been demonstrated by further analysis that the optimal ratio (Kopt) of leaf mesophyll varies with environmental light condition. The fraction of palisade tis sue which makes up the total leaf thickness increases with environmental light intensity, and the optimal ratio (Kopt) depends on the photosynthesis properties of palisade and spongy tissues (Table 3).

Biodegradation of petroleum hydrocarbons and phenol substances in soil and soil enzyme activities

Zhou Likai, Zheng Qiaoying, Song Mei

1990, 1(2):  149-155. 

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This simulation study deals with the biodegradation processes of petroleum hydrocarbons and phenol substances in soil and their relations with soil enzyme activities. Results show that the biodegradation rates of these pollutants are higher when in low concentra tions and under normal soil moisture condition than in high concentrations and under waterlogged. Chemical structures of pollutants also give an influence to the rates:a lower biodegradation rate can be found for the pollutant having a more stable and complex chemical structure. The biodegradation process of hydrocarbons and phenol relates closely with the activities of soil invertase and polyphenoloxidase respectively, and hence, the intensity of these activities could be respectively used as an index indicating the pollu tion degree of soil by petroleum hydrocarbons and phenol substances. To say the least, a certain extent of pollution by these pollutants does not exert an obvious influence un favourable to the biological activities or transformations of C, N, and Pin soil under normal soil moisture condition. Based on these results, suggestions on land treatment of these pollutants are put forward.

Influence of industrial pollution source on soil animal communities in agro-ecosystem of Xiangjiang River Basin

Wang Zhenzhong, Zhang Youmei

1990, 1(2):  156-164. 

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Investigations on soil animal communities in major industrial areas of Xiangjiang River Basin demonstrate that in croplands close to pollution source and abundant in polluted substances, the kinds and amounts of soil animals are distinctly decreased.The pollution of croplands is mainly caused by the accumulation of heavy metals in soil. Through in vestigations, 29 kinds of soil animals are collected, which can be divided into 10 clas ses belonging to 4 phyla. As pollution degree goes up, the kinds and amounts of soil animals are decreased.The density of soil animals has much to do with the concentration of such heavy metal elements as Hg, Cd, Zn, Cu, As and Pb existing in soil , which has been further proved in simulated experiments of soil pollution.

Behaviour of Co-60 in artificial marine microhabitat

Cai Fulong, Cheng Ying, Xu Plan

1990, 1(2):  165-171. 

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The behaviour of Co-60 was comprehensively studied in a marine microhabitat in the presence of Cs-137, Cs-134, Zn-65, Fe-59 and Mn-54 by appling artifical modeling.The result showed that after getting into sea water, Co-60 was rapidly adsorpted by suspen sates and phytoplanktons. The concentrative ability of sediments for Co-60 was very low, its concentration coefficient was 3—4 in96 hr. The distribution of Co-60 in marine organisms and biochemical materials was studied at the same time. The critical organs for concentrating Co-60 were liver(or digestive-g'and) and stomach-intestine. The Co-60 in the great majority of biochemical materials can be detected except organic acids.Co-60 is mainly distributed in lipid, then in protein. After excretion experiment, the loss of Co-60 in stomach-intestine and biochemical materials was marked.However, the remain of Co-60 in liver(or digestive-gland) and protein of Arca subcrenata was 50% and 83% respectively. The concentration coefficient of Co-60 in sediments was 1—10 times compa red with the original.

Electron spin resonance spectrum from overwintered korean pine seedlings

Jin Yuehua, Tao Dali, Du Yingjun, Wang Miao, Gao Juneheng, Du Yiajin

1990, 1(2):  172-176. 

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Single-peaked ESRsignals with g factor 2.0044 and 2.0037 were clearely shown respecti vely from overwintered korean pine needles and their lyophylized chloroplasts. The more serious the injury of the needles, the stronger the signal. The signals were diminished by adding Vc or fruit juice of Elaeagnus angustifolia containing rich SODand other free-radical scavengers.The more serious the injury, the more effective of the fruit juice, but Jess of Vc in inhibiting the ESRsignals. The results indicate that the winter injury of korean pine seedlings is related to the formation of organic free radicals. The major kinds of the radicals are differ in advancing stages of the injury development.

Theoretical and applied studies on predator-prey interaction

Shang Yuchang

1990, 1(2):  177-185. 

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Population interaction between predator and prey is one of the central subjects of study on animal population ecology for a long time. There are three major types of study. The first is theoretical. Here various mathematical models have been constructed to simulate the behaviour of interacting predator and prey population. The second is experimental, in which, properties of actual predator-prey population systems are compared with theoretical models. The third is represented by field investigation, in which, naturally occurring interactions between predator and prey are analysed in the light of various principles derived from theoretical and experimental types of study. In the field of applied ecology, there have been many attempts to achieve the biological control of pests by introducing new and more effective natural enemies into their natural or semi-natural population systems, sometime having attained the goal, and sometimes ended in failure. These attempts can all be regarded as field experiments on predator-prey interactions in the real world.

Soil testing for trace elements and its application

Zou Bangji

1990, 1(2):  186-192. 

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In the development process of soil testing for trace elements, the test techniques are being improved, abilites of soil in applying available trace elements are revealed more thoro ughly, and positive roles of soil testing in fertilization and protection of ecological en vironment are played more obviously.Recently, the test means adopted widely are AAand ICP, but photometry and polarography still occupy a certain position in soil test of trace elements, because of their handy equipments and the improvement of their sensitivity and accuracy. Available trace elements in soils are mainly extracted by selected extractants, techniques for directly extracting soil solution are improved, and hence, it may be possible to easily determine the level of trace elements in soil solution. Critical values or criteria may be evaluated by various methods and act as a bridge in the application of test values. The author adopts the criteria to grade test values of soil available trace elements in Taching and make maps, so as to ascertain the deficiency area and fertilizer-demand regions.Then, effects of fertilization and economic benefit may be forecasted by means of functional relation between level of available trace element and yield increase percentage.