Table of Content

25 July 1993, Volume 4 Issue 3

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Articles

Age structure dynamics of virgin Larix gmelini forest

Xu Huaeheng, Fan Zhaofei

1993, 4(3):  229-233. 

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The results of age structure study on virgin Larix gmelini forest with different disturbed levels show that the dynamics of age Structure of one generation stands is characterized by the increase of population density and age range at young stage and by the decrease of age range during the course of natural thinning at mature and old stages. Multigeneration stands are patchy mosaics in different onegeneration stands, in which, old and young generation populations have a less age variance, and middle -aged or mature generation populations have a greater age variance. In mixed Betula platyphylla and Larix gmelini stands, the mean age of Betula platyphylla is 5-15 years older than that of Larix gmelini because of its earlier colonization at early stage, but after 50 to 70 years, that of the latter is greater due to the death of older individuals of the former.

Fruitage of Larix gmelini and its relation to age structure of short branches

Xu Zhenbang, Chen Hua, Chen Tao, Shao Chunhai, Yang Shanxun

1993, 4(3):  234-240. 

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Larix gmelini forest at Daxingan Mountains fruited again in1991 after 1989's fruitage. The average fruiting rate is 63.8％, and most fruited trees are found on burned stands. The fruiting rate of larch trees with a DBHover 28cm is more than 80％, and most of these trees(more than 85％) have a sparse crown. Many fruited cones are mainly located in the middle part of crown. Most short branches are 1-2 years old, but the fruited short branches are 3-7 years old. Every seed year needs to consume many short branches. Most flower buds are male ones, but female flower used for forming cones is only 20％. Therefore, the higher the existing rate of ripe short branch is, the greater the fruiting potential and the possibility of occurred seed year are.

Fine roots turnover in a broad-leaved Korean pine forest of Changbai mountain

Shan Jianping, Tao Dali, Wang Miao, Zhao Shidong

1993, 4(3):  241-245. 

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Biomass productivity and annual turnover of fine roots in a broad-leaved Korean pine forest of Changbai mountain and their role in the allocation of net productivity are studied in this paper. The biomass of living fine roots is 5049,and that of dead ones is 1883kg. ha^-1 on an average. Annual turnover of fine roots is 0.96. Their annual production is 4860kg. ha^-1. yr^-1,being19. 40％ of total net productivity,and annual mortality is 2344kg. ha^-1,corresponding to 60％ of annual litter fallen. It is concluded that forest litter should include above-and under-ground litters.

Seasonal dynamics of nutrient release from decomposing Kandelia candel fallen leaves

Fan Hangqing, Lin Peng

1993, 4(3):  246-249. 

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Seasonal dynamics of K,Ca,Mg and Preleases from decomposing Kandelia candel fallen leaves at Jiuiongjiang River estuary of Fujian province are studied. The results show that the element composition of decaying leaves is varied significantly with different loss rates of nutrient elements. Their loss rate is larger than dry matters' and in the order of K>Mg>Ca and K>P. p loss is faster than Mg and Ca in winter, but in contrast in summer, and no difference in other two seasons. The loss amount of K, Ca, Mg and Pin decomposing leaves after 56 days is respectively 72—97, 51-88,60—90 and 64—79% of their initial amount.

Simulation experiment analysis on rainfall distribution process in forest canopy

Pei Tiefan, Fan Shixiang, Han Shaowen, Zheng Yuanchang, Niu Lihua

1993, 4(3):  250-255. 

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It is found through analysis that the throughfall and stemflow processes in canopy bear a strong resemblance to the transient course of series connection circuit of inductance capacitance and resistance. Thereform, an analytic result in terms of circuit transient equation and fitting throughfall and stemflow processes is obtained. Finally, the expression of interception intensity is obtained by means of remainder method.

Structure of tea plantation's ecoboundary layer and its variation pattern

Wang Xinli, Hsiung Wenyue

1993, 4(3):  256-259. 

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Characteristics of vertical structure of tea plantation's ecoboundary layer and its variation with time and weather conditions are discussed in this paper. Twigs and leaves are very closely arranged in a tea canopy. Inversion and positive gradients of vertical distributions of temperature and humidity occur within the canopy owing to the influence of plant physiological activities on a clear day. The maxima of temperature and humidity appear near the leaf layer, where from, they decrease downward and upward. The features of vertical structure vary with time and weather conditions. The crown canopy of tea ecosystem, including concentrated leaves and branchlets and their environments, should be recognized as an ecobody because the interactions between" organisms and their environments within the crown are so strong that they could not be separated from each other and be characterized by a special ecological function. On larger scales, ecobody plays a special role in the exehanges of material, energy and information between canopy and its environment.

Distribution of hydraulic resistance and water potential in soil-plant-atmosphere continuum during growing period of maize

Kang Shaozhong, Liu Xiaoming

1993, 4(3):  260-266. 

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Based on the data measured in maize field, the distribution patterns of hydraulic resistance and water potential in soil-plant-atmosphere-continuum (SPAC) are analysed. The difference of water potential between soil and maize leaf is about 0. 8-1.0 and 1.0—1.5MPa before and after heading stage,and the corresponding value between leaf and atmosphere is respectively 80-120 and 60—80MPa. The hydraulic resistance in SPACis mainly existed between leaf and atmosphere. Adynamic simulation model of maize leaf water potential is established,and the simulated leaf water potential is in good agreement on measured data. This paper also reveals the relationship of leaf transpiration rate with water potential difference between leaf and atmosphere and hydraulic resistance. When the water potential difference between leaf and atmosphere is larger than. 90—100MPa, the leaf transpiration rate is decreased with increasing water potential difference.

Ecoiomic planning research in developing and utilizing hilly and mountainous land at Nanfen township Ⅰ: Establishment of multiple objective programming model

Lu jianbo, Wang Zhaoqian, Ma Yue

1993, 4(3):  267-271. 

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Using multiple objective programming method, a multiple objective model for developing and utilizing hilly and mountainous lands is established. Through the solution of the model and the analysis of shadow prices, a desired planning is made, which optimizes the system structure and improves the ecolomic objectives. It's concluded that the proportion of economic forest should be increased to raise the economic benefits and outputs, the planting area of fuelwood forest should be enlarged to improve the supply of rural energy resource, the structure of timber forest should be adjusted, and more green manure crops should be interplanted to enlarge the resources of forage and organic fertilizer and to control the water and soil erosion.

Forecast of land use pattern change in Dongling District of Shenyang: an application of Markov process

Xu Lan, Zhao Yi

1993, 4(3):  272-277. 

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Based on the data obtained from remote sensing aerial photographes and topographic maps during three different periods, the transition probability of land use pattern in Dongling District of Shenyang is defined, and the tendency of its change is forecasted with application of Markov process. The resuits show that over a long period of time, the arable land area will be decreased gradually and the area occupied by residence, factory and mine will be increased day by day. Finally, the land use pattern will be lied in a stable state, e. g. , non -irrigated farmland occupies by 20. 66%, paddy field by 28.41%, residential area and factory-mine by 37.42%, vegetable field by 6.15% , forest land by 4.36％. At that time, a new land use pattern of urban and rural integration will be formed.

Trophic relations of arthropod community in paddy fields

You Minsheng, Pang Xiongfei

1993, 4(3):  278-282. 

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This paper deals with the trophic structure and its types of arthropod community in paddy fields based on outdoor surveys and indoor experiments. In paddy field ecosystem, complex food chains and food webs may be formed because of the interspecific relations of feeding, parasitism and predatism. According to the living patterns of parasitic species in food webs, the trophic structures of arthropod commonity in paddy fields of Fuzhou suburbs can be divided into three types: 1) no link of epiparasitism in food webs; 2)some links of epiparasitism in food webs; and 3) some links of double parasitism in food webs. By using the knowledge and operation rules of graph theory, a food web can not only be described as a signed directed graph(SDG), a set, or an adjacent matrix, but also be combined with others. The method has been proved valuable in the studies of trophic relations of a complex community.

Relationship between contents in "Qinyou2" rape and population dynamics of Myzus persicae

Zou Yunding, Meng Qinglei, Hu Lijuan, Yang Yihe, Huang Shixiang

1993, 4(3):  283-288. 

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The influence of contents in "Qinyou 2" rape under application of different rates of N, Pand Kfertilizers of Myzus persicae is studied, and nine mathmatical models are established. The results show that soluble carbohydrates, potassium and moisture contents in rape plants affect significantly the population dynamics of Myzus persicae. The combination of lower Nand Kand midium Pis disadvantageous to Myzus persicae population growth.

Determination of soil salt content with electromagnetic induction conductometer (EM38)

Zhang Weizheng, Yin Lijuan

1993, 4(3):  289-294. 

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Determining soil electromagnetic induction conductivity (EM) in situ with EM38 is a new and convenient method for rapid determination of soil salt content. Deposing EM38 horizontally at different heights above the ground, the variation of EMreadings has a relation to the salt contents in different depths of soil layer. Electric conductivity (EC) is also determined by electric conduction method in laboratory with soil water extracts (water: soil=5: 1). Correlation analysis shows that EMreadings at different heights above the ground have a significant correlation to ECreading at different depths of soil layer. Regression equations for ECare established based on EMvalues, and inserting corresponding EMvalues, the ECvalues and salt contents in different depths of soil layer can be solved.

N₂O emission by plants and influence of fertilization

Li Nan, Chen Guanxiong

1993, 4(3):  295-298. 

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It is verified that plant is a new N₂Oemission source. The N₂Oemission rates of soybean, spring wheat and millet at different growing stages and that of spring wheat fertilized at several fertilization levels are measured by using open chamber method and C₂H₂ inhibitory technique. The results indicate that the N₂Oemission rates of these three kinds of plants increase gradually in early growing stages and reach the maxmium before and after blooming stage, and then decrease sharply. Significant difference in N₂Oemission rates among tested plants is found at the relative development stages. Of these plants, soybean shows the hightest N₂Oemission rate. Under different fertilization conditions, both growing status and N₂Oemission rate of spring wheat are different and the excess fertilization rasults in a higher N₂Oemission rate.

Influence of long-term aridity on morphological characteristics of legume nodules in Xinjiang

Lin Jishang, Wang Lixia, Guan Guilan

1993, 4(3):  299-302. 

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Nodules of three legume species, Sopora alopecuroides, Astragaous sp. and Vicia costata in Xinjiang are studied on their morphological characteristics with light microscopy and EM. It is found that the shape and structure of nodules are influenced by local environment. Under long-term aridity and high soil temperature, they have a thicker cortex, which as a flexible barrier supports a moderate microenvironment for bacteroids within the nodule. No relationship between ultrastructure of nodule's central zone and dry environment has been found in this study, although there is an obvious structural difference among tested legume species.

Influence of supplemented selenium on chemical forms of selenium in crop seeds and their quality

Cui Jianbo, Yin Zhaohan

1993, 4(3):  303-307. 

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Supplemented selenium in seeds can be classified as water soluble, K₂SO₄ extractable, NaOHextractable and non-extractable forms, and the main ones are NaOHextractable and water soluble Se. Se (Ⅵ) occupies a certain proportion in various forms of Se and varies with increasing supple mented Se. The proportion of various forms of Se in crop seeds is varied with supplement of Se, which can increase the amino acid content in seed and may influence its hereditary characteristics.

Control of harmful microbes in industrial circulating water by bactericidal algicide OACL

Zhang Jingyuan, Gao Huiming, Li Aimin, Meng Qingheng, Zhuo Yue, Xu Dayong, Zhang Jie

1993, 4(3):  308-312. 

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The effect of bactericidal algicide OACL on heterotrophic bacteria, sulfate reducing bacteria and iron bacteria is studied, which shows that in laboratory, the bactericidal rate is more than99% on average, and 97.8 and 88% at pH5 and pH7 respectively. In a field experiment with OACL, the bactericidal rate is more than 92%.

Effect of acidic water on survival, growth and reproduction of freshwater snails

Liu' Baoyuan

1993, 4(3):  313-318. 

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Laboratory studies with Radix swinhoei and Bellamya aeruginosa show that R. swinhoei is tolerent toward low pH, its value being3.96 for LC₅₀ during 96 hours. When pHvalue is below 5.0, freshwater pulmonate snails produce less cocoons, their hatching period is longer, and the growth of Young snails is slower. At 35th and 45th day of growth, the growth rate of young B. aeruginosa is respectively 1.21 and 1.07% at low pH, and only 0.18 and 0.29％ at pH5.0, pH5.5 has no significant effect on freshwater-pulmonate snails, and pH3 induces their death.

Relation of crop yield to feeding injury by indirect insect and mite pests Ⅱ. Reproductive organ chewing insects

Sheng Chengfa

1993, 4(3):  319-324. 

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This paper attempts to draw a general relationship between crop yield loss and chewing injury of reproductive organs by insect pests. It is found that there are some common characters of yield response to reproductive organ damage for different crops. At the early stage of reproductive growth,the removal of all or parts of the reproductive organs results frequently in an increased yield. At the late stage, the removal of young organs has little or no negative effect on yield. While at the middle stage, the removal causes a severe yield reduction. Other factors also affect the relationship. Crop yield tends to decrease if large amounts of reproductive organs are damaged,crop variety has a late maturing or determinantly growing property,soil water and nutrient eonditons are relatively bad, cumulated temperature or sunshine are not enough, compensation duration is rather short,plant density is too high or too low,middle stratum organs are damaged,or reproductive organs suffer a follow-up damage. The yield response to reproductive organ loss is similar to that to leaf area loss. This generalized knowledge is needed in improving crop loss assessment and developing IPMprogram for a region planted with different crops.

¹³C/¹²C ratio and water use efficiency of Pinus massoniana in subtropical artificial forest

Sun Guchou, Lin Zhifang, Lin Guizhu, Li Shuangshun

1993, 4(3):  325-327. 

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The ¹³C/¹²Cratio, photosynthetic rate and stomatie conductivity of leaves of Pinus massoniana, Schima superba,Psychotria rubra, Evodia lepta and Rhodomyrtus tomentasa are measured. No significant deviation (at 5% level) is observed between water use efficiencies calculated by these items. The¹³C/¹²Cis 25.41±0.61‰. In average for treerings of Pinus massoniana from 1971 to 1983(n=6), with the maximum in1977 when the lowest precipitation was recorded. The average water use efficiency of Pinus massoniana is 8.28±0.38 in1977—1983, which is higher than that of trees in natural site and might be caused by the changes of solar radiation and water condition. ¹³C/¹²Cratio ana lysis could provide usefull informations for studying water use efficiency of artificial forest.

Analysis of ecological factors of macrofungi in Sheshan hill

Wu Renjian, Tan Huic

1993, 4(3):  328-333. 

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Ecological factors affecting the growth and development of macrofungi in Sheshan hill are analysed. It's concluded that spatial distribution of macrofungi is depended on substrates or hosts, and their time distribution is influenced by moisture and temperature.

Purification of beer wastewater by Lolium multiflorum

Dai Quanyu, Chen Zhao

1993, 4(3):  334-337. 

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Purification efficiency of beer wastewater by Lolium multiflorum is studied by means of soilless cultivation techinigue. After a 120 hours static experiment, the purification rate of TN, TP, COD, NH₄⁺-N, NO₂^--N, NO₃^--N and turbidity is respectively 54.1,82.19,66.34,69.69,90.91,57.80 and 92.59% in March,and that of TN,TP, NH₄⁺-N, CODand turbidity is 95.2,98.34,99.76,75.09 and 82.98 in May. It is proved that Lolium multiflorum can be used for purifying beer wastewater under lower temperature.

Spectrum analysis in steppe vegetation research

Huang Jingfeng

1993, 4(3):  338-341. 

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Maximum entropy spectrum and cross spectrum methods are used to study the effect ot climatic change on grass yield. The results show that climatic fluctuation can result in annual variation of grass yield. The time series of grass yield has an equal or approximate variation period of climatic elements and its response has a lag effect. Precipitation is a dominant factor affecting grass yield fluctuation.