Table of Content

25 October 1996, Volume 7 Issue 4

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Articles

Stability of Mongolian pine plantations on sandy land

Zeng Dehni, Jiang Fengqi, FanZhiping, Zhu Jiaojun

1996, 7(4):  337-343. 

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This paper defines the meaning of artificial forest stability and its evaluating standards. The various disturbing factors affeCting the stability of Mongolian pine plantation on sandy land were analyzed. Detailed studies were carried out on evaluating the survival degree of planting, the growth, the ability of resisting the adverse circumstances, life length, and the structure and the productivity of forest stand. Results show that the artificial forest stands of Mongolian pine introduced to sandy land are basically stable. The stands bowing on low sand dunes are more stable than those growing on high sand dunes. The young forests have higher disease-resistance than do the middle-aged forests. According to the density and the productivity of it, the stand growing on Honghuaerji sand land is more stable than in Zhanggutai.

Morphological character and biomass of Avicennia marina seedlings

Liang Shichu

1996, 7(4):  344-348. 

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The investigation of one-year-old Avicennia marina seedlings cultivated in sand beds irrigated with natural sea-water indicates that some quantitative indices such as plant height, basal diameter, root length, pneumatophore height and leaf area and weights of root, stem, branch,leaf, viviparous seedlings and whole plant show a pattern of their arithmetic mean> median>median of mode interval, which accords with poSitive deviate distribution. The arithmetic mean of some enumerative indices Such as numbers of node, leaf, pneumatophore and viviparous seedling of anllual seedling equals to their median. both of which are equal to or larger than the median of mode intervals. It also shows that annual Avicennia marina seedlings can grow the pneumatophores. flower and fruit, and propuced viviparous seedlings which after maturation,can directly develop into new seedlings. Based on the data obtained, 30 regressive models on the morphological factors and hiomass of annual A. marina sablings are built up using linear,multilinear and non-linear regression.

A disturbed ecosystem Ⅱ. Nitrogen cycling and its regulation in tussah-feeding oak plantation

Wen Dazhi, Yang Sihe, Don K. Lee

1996, 7(4):  349-353. 

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The relationship o[ nitrogen cycling in tussall-feeding cab plantation with feding intensity of tussah silk worms, soil fertility and period of cutting branches and leaves is revealed in this paper. It is shown that cocoon pnduction and Periodical cutting of branches and leaves are the main factors affecting the N balance in tussah-feeding oak plantation. The intensity of feeding tussah silk worms and the pened of cutting branches and leaves must be defined in accordance with the fertility level of soil and tile growth intensity of tree. Regulating the compoLsition of ground vegetation by planting N-fixing speCies can obviously improve soil N condition.Application of N-fertilizers is an effective measure to enhance the nurse oak tree growth and to reinvigorate the growlh of deteriorated oak trees with old root system.

Role of nitrogen-fixing trees in mixed forest Ⅰ. Nitrogen fixation and tree growth of mixed stand with Hippophae rhamnoides

He Xingyuan, Zhang Chenggang, Yang Sihe, Zhang Yue, Su Daoyan, Liu Huichang

1996, 7(4):  354-358. 

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The role of Hippophae rhamnoides as the undergrowth in mixed forests was studied. The results show that H. rhamnoide has a significant effect of N supply, and its annual average N fixing amount is 54 kg· hm^-2 in 7 years old stand, Comparing with pure Populus sp. And Salix matsuda na stands, nitrogen content in soil of mixed stand is increased by 20～22%, and height increment of main trees by 18～19.4%.

Light characteristics in tea-fruit tree or-forest complex garden

Guo Suying, Duan Jianzhen

1996, 7(4):  359-363. 

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The transmissivity of the deciduous trees in the upper canopy of tea-fruit tree or-forest complex garden is 2～15% higher than that of the evergreen trees, up to 30% especially in spring. The transmissivity had not remarkable effects on the tea yield, when it was kept more than 55%.The amount of scattered light under canopy at 12 am～2 pm is more than the 11ght saturation point 2.9 J. cm^-2· min^-1 of tea tree. The amount of scattered light in deciduous trees reaches to 65～80% of total radiation in spring, 45～60% in summer and autumn. The amount of reflected light of tea tree canopy occupies a small part of total radiation, about 5～8% in sunny days, wilhin annual range of 5～10%. The maximum range of daily change is at 10 am～3pm, which reaches to 0.2～ 0.4 J·cm^-2·min^-1 in summer and autumn. The transmission of tea tree canopy is 500～2000lux. The maximum range of daily change of transmission is 15～20% of total radiation at 4～5pm, and the amount of absorbed light is 80 ～85%.

Influence of environmental conditions on genetic performance of cytoplasmic effects and nucleocytoplasmic interaction in hybrid rice V. Effects of sterile cytoplasms on photosynthetic physiology and the activities of defense enzymes in hybrid rice under different application rates of nitrogen

Lin Wenxiong, Liang Yiyuan, Wu Zhiqiang

1996, 7(4):  364-370. 

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The results show that there is closely relatlonship between the effects of sterile cytoplasms on dry mat ter pdriuctlon and partioning and on the yield performance o[ hybrid rice at late growth stage. Nonsignificantly-positive sterile-cytoplasmic effects on dry matter production, ranging from 1.37～1.47g·m^-2·day^-1 on an average, are found at early growth stage of hybrid rice across 4 supply N treatments, but the situation is quite different at late growth stage, especially in exposure of hybrid rice to nitrate stress. The nonsignificantly-positive effects of sterile cytoplasms on dry matter production and on the grain yield of hybrid rice are detected, in turn leading to increased grain yield of hybrid rice under favorable nitrogen conditions(150～240 kg N·hm^-2 ), the reverse is true under unfavorable nitrogen supply(≤60 kg N·hm^-2 or≥330 kg N·hm^-2 ). Further analysis suggests that this process is closely related to the activities of RUBPcase, ATPase and defense enzymes at late growth stage of hybrid rice, indicating the same reaction of cytoplasmic effects on them, particularly under the nitrate stress. Finally the physiological relationship between polyamine metabolism and changes in the activities of defense enzymes and the amount of free radicals is also discussed in this paper.

Water balance and its efficiency in rice field ecosystems of nothern China

Luo Liangguo, XuJianmin, Luo Qishi, Wen Dazhong

1996, 7(4):  371-376. 

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The water balance and its efficiency in five rice field ecosystems were studied at the lower reaches plain of Liaohe river from i993 to 1995. The resulls show that there is a significant difference of total water consumptioll among different rice field patterns. Comparing with conventlollal pattern, the improved irrigation and improved irrigation-[ertilization patterns can save 15～23% of itrigatioll water and increase 30% of water efficiency. During the same growing season, each pattern has a similar evapotranspiration, and field stlxicture and control nlanagemen[ have no influence on it. During rice development pened, the difference between field and potential evaPOtranspirations is less than 5%.

Effect of supplemented polyamines on the germination and early growth of rice and their adsorption in soil

Kong Chuihua, Hu Fei, Xie Hualiang, Luo Shiming

1996, 7(4):  377-380. 

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The effect of supplemented polyamines in different concentration on germination and seedling growth of rice was studied. The results show that the germination and seedling growth of rice,especially root growth are inhibited by supplemented polyamines. The extent of the inhibition is in the order of spermindine> putrescine>cadaverine. However, they can significantly enhance chilling resistance of seedling growth of rice. The study on the extractibility of cadaverine from alltoclaved soil extracted with water or solution of Na₂EDTA and HCI indicates that most of it will be adverbed by soil. The soil adsorptloll of cadaverine is reversible in the existence of acid and complexing agent.

Species diversity of main communities in South Songnen Plain

Wang Renzhong, Li Ji, ong

1996, 7(4):  381-385. 

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In this paper, the species and life form diversities of fourteen main communities in South Songnen Plain and the relationship between species diversity and community succession are analysed by using Margalef and Menhinick richness indices(R₁, R₂ ), Hill cliversity indices(N₁,N₂) and Pie1Ou evenness index(E). The results show that the species diversity and richness index of Leymus chinensis-Potentallia flagellaris community distributed on lowland are thehighest, those of Ulmus Pumila, Stipa baiclensis, Stipa baiclensis + Filifolium sibiricum and Stipa grandis communities distributed on dunes are the second. while the corTununities distributed on alkalized meadow, such as Suaeda corniculata, are the lowest. Communities with higher species diversity have a higher life form diversity. The species diversity index of Anenrolepidium chinense community is situated at the stage between initial and middle successional series.

N₂O emission from grassland soils and the teedback effect or nutrient changes resulting from global warming

Yang Yonghui, P. Ineson, A. F. Harrison, P. Coward

1996, 7(4):  386-390. 

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Studies on N₂O emissions from grassland soils and its influence by nutrient changes resulting from global warming show that in growing season peaty gley soil has a maximtun N₂O emission varying from 1.3 to 12.2 kg N·hm^-2·yr^-1, N₂O emission in ndcropodzol soils is from 1. 5 to 2.4 kg N·hm^-2· yr^-1, and acid brown earth has the lowest ranging from 0 to 3.2 kg N·hm^-2·yr^-1.N₂O emission mainly comes from top 5cm in micropodzol soil, and from top 10cm in other two soils. Fertilizer application in growing season doesn't make any differece in different soils. However, N application greatly stimulates the N₂O emission at the end of the growing season. And in acid brown earth and in micropodzol soil, it reached respectively 44.2and 33.1 kg N·hm^-2·yr^-1 compared to 1.3 and 1.9 kg N·hm^-2·yr^-1 in the control. This implies that the influence of global warming upon decomposition of organic matters doesn't result in a significant increase in N₂O emission.

Survival and distribution of Frankia introduced in rhizosphere of actinorhizal plants

LinJianqun, Zhang Zhongze, Su Fengyan, Wang Yuying, Li Weiguang

1996, 7(4):  391-395. 

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Trace Frankia in the rhizosphere of Casuarina cunninghamiana can betected through hybridization of Frankia 16SrRNA with synthetic speific complementary oligonucleotides.The results show that Frankia are migrated under the influence of environmental factors. After 6 months, their distributions in different inoculation points are samilar, and concentrating at 8～30 cm soil layer.

Study on soil sickness by soybean continuous cropping I. Effect of mycotoxin produced by Penicillium purpurogenum

Hu Jiangchun, Wang Shujin

1996, 7(4):  396-400. 

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Microbial comunlty in soil of soybean continuous cropping was analyzed, soil fungi were found to be abundant. soybean was inoculated with dominant fungi. The soybean growth is strongly inhibited by Penicillinm Purpuroggnum Stoll 891. Crude crystals of Rubratokins of P.purpurogenum Stoll 891 were extracted. The inoculation experiment with Rubratoxin Ashows that its concentration in water culture actives at 5μg·ml^-1, the soybean root system is injured. At 30μg·ml^-1, the primary roots are seriously necrosised and the secondary roots are almost stunted. At 200μg·ml^-1, some seedlings of soybean varieties are died within a couple of weeks. It is suggested that Pedologic mycotoxin generated by P.Purpurogenum Stoll which is abundant in soybean continuous cropping soil may be one of major factors leading to soil sickness.

Restoration of aquatic vegetation and its role in the ecological pool of natural resources in Lake Yunihu

Yu Dan, Zeng Yiben, Zhang Hanhua, Chen Yiyu

1996, 7(4):  401-406. 

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Stationals studies including the natural restoration process of aquatic vegetation, community composition, structure, dynamics and function were conducted in Lake Yunihu. 41 aquatic plants found in Lake Yunihu falls into 20 families and 29 genera. Four life-forms of plants distribute all over the lake, with emergent (15 species) and submergent (13 species) plants predominant in numbers. There are 8 distribution types consisting of 16 worldwide components and 10 East-Asian components. Strata and sguusia structures are dealt with in community structure study.8 commnunity types are classified. The standing biomass of communitites is 3268.8 g·m^-2 and the total crop in the lake is 16365.2tons.

Plant allelopathy effects on Oncomelania hupensis

Yu Fengan, Peng Weiping, Peng Zhenhua, Zhang Jialai, Liu Lide, Peng Danming

1996, 7(4):  407-410. 

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The dynamics of grasses in herb layer on beaches with snails and inhibition effects of Sapium sebiferum and Pterocarya stenoptera on snails were studied. Individual quantity of Paederia scandens(X² = 12.8 ) and Oenanthe javanica (X² = 11.2) are positively, and that of Leonurus artemisia, Equisetum arvense, Rumex acetosa, Calystegia hederacea and Astragalus sinicus are negatively correlated with the density of snails(a<0.02 ). After the flooding period,the mortality of snails on beaches treated with leaves of Pterocarya stenoptera and Sapium sebiferum is increased by 43.3% and 44.1%, respectively.

Seasonal change of blood cell number of Trionyx sinensis and its shape and structure

Cheng Beijiu, Jiang Like, Song Xiangfen, Ling Xingyuan, Zhu Suwen

1996, 7(4):  411-416. 

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The shape and fine structure of peripheral blood cells of Trionyx sinensis and its number and types in different seasons were studied. The results show that the number of erythrocyte and leucocyte is varied with seasons. The numbers of erythrocyte and leucocyte in August and May are increased respetively, and are decreased distinctly in hiberating stage (February).Neutrophils lymphocytes, thrombocytcs, basophils, eosinophils and monocytes occupy respectively 48, 20, 18, 6, 4 and 4% in leuorytes. The volume of its erythrocyte is larger. The leucocytes are stable to some acid and alkali elements.

Effect of Cd on quality, physiological and biochemical characteristics of mulberry leaves and its mechanism

Chen Chaoming, Gong Huiqun, Wang Kairong

1996, 7(4):  417-423. 

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Effect of Cd on yield, quality. physiological and biochendcal characteristics of mulberry leaves and its distribution in subcellular fractions under different Cd levels in soil are studied in this paper. The results show that yield and contents of soluble sugar and N-containing compounds in leaves are higher than control or similar to control, and chlorophyll content, cell membrane permeability and activities of SOD, POD and Protease in mulberry leaf show little changal comparing with control, or even have certain promotive effect under lower Cd concentration of soil (<22.3mg·kg^-1). When Cd concentration in soil is higher than 22.3mg·kg^-1, yield,nutrient contents, physiological and biochewhcal properties of mulberry leaves show distinct changes, and the injury blame heavier with the increase of Cd concentration in soil. The mechanism is analyzed by distribution of Cd in subcellular fractions of mulbo leaves.Therefore mulberry can be regarded as a kind of Cd-tolerant cash crop and it is possible to grow mulberry in Cd pouuted soils.

Effect of fluoride pollution on fecundity of Bombyx mori

Chen Yuyin, Shao Sihal, Wu Tianjun, Wu Yucheng

1996, 7(4):  424-428. 

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Artificial administration of gradient NaF solution to the fourth or fifth instar larvae of Bombyx mori larvae for 48 or 96 hours shows that NaF administration to the fourth instar for 48 hours has no negative effect on the fecundity of B. mori if the female larvae has normal pupation, eclOSion and egg laying, but the number of formed and laid eggs, percentage of laid eggs and hatchability are significantly decreased when 11igh concentration of fluoride is fed to the fifth instar larvae. However, low concentration of fluoride has a poSitive effect on the fecundity of the highly fluoride resistant variety -Zhenong 1. The ingested fluoride mainly distributed in midgut tissues and Malpighian tubules is not transferred to the eggs.

Degradation of 1,2,4-trichlorobenzene (1,2,4-TCB) in soil

He Yaowu, Sun Tieheng, Ou Ziqing

1996, 7(4):  429-434. 

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Degradation of 1,2,4-TCB in soil was studied under both aerobic and anaerobic conditions. The results show that both aerobic and anaelxibic degradation of 1,2,4-TCB obeys the first order dynamics. Under same water content, temperature and initial concentration, the aerobic degradation is rapider than anaerobic one with half-lives of 1.89～5.86 and 5.07～19.08 days respectively. Initial concentration of 1,2,4-TCB significantly affected the degradation rate, with initial concentration ranging from 0 to 100μg·g^-1,higher concentration promotes the degradation. Higher temperature within the range of 10～30℃ accelerates the degradation due to the activation of microbial enzyme at high temperature.

Effect of amino acids in root exudates from Eichhornia crassipes on degradation of phenol by its rhizospheric Enterobacter sp. F₂

Zhao Dajun, Zheng Shizhang

1996, 7(4):  435-438. 

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In this paper, the effect of methionine(Met) and lysine(Lys), two typical root exudates from Eichhrmnia crassipes, on the degradation phenol by its rhbopheric Enterobacter sp. F₂ is studied. Met, an attractant, doeS not affect the growth, enzyme activity and phenol-degrading efficiency of F₂, but Lys, a negative chemotaxic amino acid, call inhibit them under high concentrations (10^-2 or 10^-3mol·L^-1 ), and the inhibition effect is weackened progressively with its decreasing concentration. Amino acids in root exudates from Eichhornia crassipes act as partial information flows of its rhizospheric micrxiystem and affect phenol-degrading efficiency of the system.

Riparian vegetation characteristics and their functions in ecosystems and landscapes

Chen Jiquan

1996, 7(4):  439-448. 

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Stream network, riparian sone and river continuum concepts and other related theories and applications are becoming critical components of ecology. In this paper, the development,debate and apphcation of the above concepts are summarized based on the literature from North AInerica and the compeitional and structural characteristics of riparian vegetation and their roles in stream ecosystems and landscapes are discussed in the context of natural resource and ecosystem management.