Table of Content

10 December 1989, Volume 8 Issue 06

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Energy Efficiency of Farmland in Poverty-stricken Areas of the Loess Plateau and Approaches for its Improvement

Yu Cunzu, Liu Yaohong, Peng Lin, Dai Minjun

1989, (6):  1-5,26. 

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The energy efficiency of farmland was lower in poverty-stricken areas of the Loess Plateau.It had positive correlation with farmland area per capita and negative correlation with cereal area per capita and degree of soil erosion. To improve the energy efficiency,we should control the erosion, improve the agro-ecological environment, abstain from extensive cultivation and increase material input rationally.

Root-system Distribution in a Tea Plantation with Interplanted Slash Pine

Tang Rongnan, Tang Xinglu

1989, (6):  6-10. 

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In a tea plantation with interplanted slash pine, the lateral roots of pine trees were mostly distributed in the upper layer of soil (C—40cm), while most roots of tea in the depth of 0—60cm, Such a vertical distribution of root systems enable these two species to fully use the soil resources, On the other hand, the horizontal distribution of 14-year-old pine roots exten ded to more than 3.75m with a concentrated scope of 1.5m, which could be limited by fer tilizing and deep ploughing in the plantation.

Rational Management of Broadleaved Korean Pine Forest and Activities of Soil Microorganism

Li Fengzhen, Zheng Hongyuan, Liu Zengzhu, Zhang Shuxian, Lu Yaobo, Liu Ruijun

1989, (6):  11-15. 

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The effects of clear and selective cuttings on soil microorganism, soil enzyme activity and nitrogen metabolisms were investigated. A 30% intensity of selective cutting made an increase of the activities of soil microorganisms which favoured the biological cycling of nutrient elements through the decomposition of litterfall. Under conditions of clear cutting and overcutting, as a result of the stimulated decemposition and nitrification, nutrient losses to streams, particularly in the form of nitrate may lead.

Analysis on Vegetations and Structure of Main Phyto-communities in Tiantong

Sun Saichu, Cai Renhou

1989, (6):  16-20,65. 

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Tiantong is situated in Jin county of Zhejiang province, near Ningbo. It is known as "State Forest Park" for its exuberance of vegetation. This paper gives a systematic account of its vegetation distribution and a structural and componential analysis of three main vegetation types. Both the account and analysis are based on sample plot investigations and resultant sta tistics.

Classification of Forest Sites in the Bingla Mountain of Liaoning Province

Li Shaczhong, Meng Kangmin, Zhao Bing, Zhu Xu

1989, (6):  21-26. 

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Methods of step multiple regression, principal component analysis and canonical ordination analysis were used to determine dominant factors in relation to site classification. Forest site regions were classified by mid-physiography, forest site groups by slope direction and forest site types by soil physical conditions and depth of soil organic matter, 21 types of forest site were classified in the Bingla Mountain.

Accessment of the Ecological and Economic Effects of Tree-shrub Mixed Sand-holding Forest in Northern Linze Oasis

Yang Wenbin

1989, (6):  27-30. 

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According to the results investigated in northern Linze Oasis for tree and shrub mixed sand-holding forests, the degree of wind reduction and micro-climate improvement increascs with the growth of afforestation years. After 8 years of afforestation, sand dune has been stabilized, wind speed is reduced by above 50%, air relative humidity increased by 6—8%, and evaporation potentiality reduced by 43—60%. After 12 years, each ha of the forest can provide timber 262.8m³, firewood charcoal 39t and litterfall 51t(dry weight) which contains (NH₄)₂SO₄ 1873.5kg, Ca₃(PO₄)₂ 96 kg and KCl 2872.5kg. The net output is 53479.2 yuan ·ha^-1. This mixed sand-holding forest has gained both ecological and economic benefits. It is valuable to be popularized in arid areas.

Preliminary Study on Quantitative Dynamics of Aphis gossypii on Cotton Plants

Zhu Changliang, Shen Zhongjian

1989, (6):  31-33. 

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Relations between A. gossypii and cotton plants have been studied. The population dynamics of cotton-aphids consists of four stages, i. e., rise, balance, collapse and oscillation in a new level. From their invasion to pre-collapse period, the population dynamics of aphids accords with a Logistic curve, which can be expressed by the equation: N=2276.8/(1+e^7.94-0.40t).

The Theory of Island Biogeography: Model and Application

Wu Jianguo

1989, (6):  34-39. 

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Dynamic equilibrium theory of island biogeography is one of the important concepts in modern biogeography and ecology. Its popularity has been explicitly reflected by a large body of literature in the past three decades. The theory has an enormous influence on perspectives of nature conservation. In this paper, the basic tenets and assumptions of the theory are outlined both qualitatively and quantitatively. The validity of the theory and its applicability to nature conservation are critically discussed. In addition, the implications of the theory to the development of population dynamics models in heterogeneous environments and landscape ecology are briefly commented.

Agro-ecological Problems and Their Countermeasures in Baoji

Chang Chongxin

1989, (6):  40-43. 

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Based on an a gro-ecoenvironmental analysis, many ecological problems exist in the agriculture of Baoji municipality of Shanxi province, such as over-consumption, forest coverage declination, soil erosion, rapid reduction in arable land, alternative appearence of arid and rainy weathers, crisis of environment pollution, etc. From the viewpoints of ecological economy, it is proposed to designate new patterns of agricultural production, to optimize productive structure in mountainous areas for the rational utilization of natural resources, to establish a rural-urban agro-ecological system and to adopt comprehensive measures and specia ecological policies for better cyclings.

Ecolomic Problems on the Utilization of Water Resources in Ningxia Autonomous Region

Lu Lachang

1989, (6):  44-47. 

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Problems on the utilization of Water resources in Ningxia Autonomous Region are analyzed from the viewpoint of ecology, and some ideas are put forward for their rational utilization.

Preliminary Analysis on Desertified Soils in Balinyouqi of Inner Mongolia

Jiang Zhanrong, Zhao Hengzhi, Wang Wenzhong

1989, (6):  48-51. 

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Investigations and analysis are made on the cause, tendency and harmful consequences of desertification in Balinyouqi of the west Keerqin Desert. Dominant factors of desertification in this area are livestock over-grazing, land over-reclamation, firewood cutting and other human economic activities. Desert area has been doubled that of 17 years ago, resulting in the declination of livestock products and economic benefits. Successful experiences of desertcontrol and stabilization are summarized and measures are put forward in line with local conditions in this area.

Origin and Development of Evolutionary Ecology

Wang Zhixiang

1989, (6):  52-55,62. 

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This paper sumarizes the origin and development of evolutionary ecology and the significance of carrying out its researches.

Chemical State of Several Heavy Metals in Black Soil

Wang Lianping, Zhang Xuexun, Song Shenghuan

1989, (6):  56-57,65. 

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By sequeatial extraction for three kinds of heavy metals, the influence of humus and its various components on the activity of Cu, Pb and Cd in black soil is discussed. Most of the Cu in soil are in organic state and insoluble residues, only a few in exchangeable stato and carbonate-combined state. The content of available Cd in soil is obviously exceeded that of Cu and Pb with increasing content of humic acid.