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Table of Content
    Volume 16 Issue 2
    10 February 1992
      
    Research Articles
    Comparative Research on the Water Potential and transpiration Rate of Chinese Pine Plantations From Different Provenances in Beijing
    Tang Ji-lin, Xu Hua-cheng
    Chin J Plan Ecolo. 1992, 16 (2):  97-107. 
    Abstract ( 1960 )   PDF (741KB) ( 856 )   Save
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    The yearly variation water potential and the daily process of transpiration rate of chinese pine (Pinus tabulaeformis) plantations in Beijing, aged 8 years, coming from 13 provenances of 7 climatic ecotypes, were determined with presseue-chamber technique and BL8503 porometer. The result showed that for all provenances, the minima of water potential are found in winter (–19.35 bar) and in the period of high temperature and dry seasons (–14.81 bar). There are distinct differences among the values of water potential from different provenances, the largest for the provenances of northeastern ecotype and the least for southern ecotype. The value of water potehtial is obviously related to the mortality in winter, the populations originning in south have the lowest water potential and the highest mortality in winter. The daily and seasonal change of transpiration rate for all provenances are apperently regular. The daytime course looks like a convex curve with high value in midday and low value in early morning and night. The curve of yearly course has two peaks. Clear differences are observed among the transpiration rates of different provenances, the northeastern ecotype with the highest value and the southern ecotype with the lowest one.
    A Preliminary Study on the Structure and Dynamics of Pubescent Hornbeam Population in Karst Mountain of Guiyang
    Liang Shi-chu
    Chin J Plan Ecolo. 1992, 16 (2):  108-117. 
    Abstract ( 2012 )   PDF (667KB) ( 611 )   Save
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    This paper deals with the structure and dynamics of pubescent hornbeam population in karst mountain of Guiyang. The results are as follows:

    1. The size structures are classified into seven types: initial growing, growing, stational, initial senescent, middle senescent, final senescent and disclimax types. Along with the population and the succession development, the size structure changes mainly from growing, senescent, extremely senescent to residual type.

    2. The spatial patterns of the populations are contagious type and random type. Spatial pattern changes with size classes of the population. It was found that the seedling, sapling and small tree classes show contagious types, while the middle and large tree classes exhibit random types. The regularity reflects the dynamic change of spatial pattern with time in development of the population.

    3. The population density tends to decrease with the population and the succession development.

    4. Pubescent hornbeam population is a pioneer of the karst forest succession on Chinese subtropics, and occurs throughout the succession. But the population at rocky steep slopes or ridges may develope into stationary community.

    A Theory of Optimal Harvest of Grassland with Water as the Main Limiting Factor
    Gao Qiong
    Chin J Plan Ecolo. 1992, 16 (2):  118-125. 
    Abstract ( 1836 )   PDF (452KB) ( 646 )   Save
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    Water is a common limiting factor for plant growth in the vast grassland in the arid and semi-arid northern China. A differential equation model for the plant-water system was constructed in this research which stresses the interaction and coupling effect between vegetation and water circulation. Two quantities, soil water content and plant biomass, were selected as state variables. The objective of the model is to describe the variation of the two quantities in a typical grouth period (one year). Theory of optimal control was then applied to the differetial equation system to obtain the possible maximum harvest with the system stability as the main constraint.
    A Study on the patterns of Biomass and Productivity of the Corn Cropland in Shelterbelt Network
    Chang Jie, Wang Wen-zhang
    Chin J Plan Ecolo. 1992, 16 (2):  126-135. 
    Abstract ( 1811 )   PDF (606KB) ( 687 )   Save
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    The time and space patterns of the biomass and biological productivity of corn(Zea mays) cropland in the shelterbelt network in SongNen plain and the relationship among the patterns, ecological and physiological factors in network were studied. Results showed that: The biomass and productivity in different position between the east and west belts had significient differences in each peroid in the growing season. The maximum biomass occured in 5—10 multiples of tree height(H), minimum in IH, and the biomass was also high in 25H. The level distribution of the productivity was "N" shape in most time of the growing season, two peaks occured in 10H and 25H respectively. The biomass and productivity between the south and north be Its had no difference. The patterns of the biomass and productivity in shelterbely network were restricted by the distribution of temperature and humidity in the network, and the restrict factor was different in different time. The leaf area and assimilate rate also had important effect on the pattern of productivity. The biomass of ear within network was higher than that in the open land.
    Relationship Between Regeneration Characteristics and Arenaceous Adaptability of Hedysarum fruticosum var. lignosum
    Liu Zhi-min
    Chin J Plan Ecolo. 1992, 16 (2):  136-142. 
    Abstract ( 1565 )   PDF (428KB) ( 876 )   Save
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    The relationship between regeneration characteristics and arenaceous adaptability of Hedysarum fruticosum var. lignosum was analysed. The results showed that there were two regenerating mechanisms for H. fruticosum var. lignosum: natural seed regeneration and natural regeneration by rhizomes,the former of which is less successful because the seeds are difficult to spread and there are a lot of factors affecting seed germination; and the latter is the main way of regeneration. Three-year-old seedlings begin to reproduce by rhizomes, which is of significant for the plant to overcome sand-burying and to guarantee its branch-shooting and existence, and which is undoubtedly one of biological properties of adaptability to mobility and aridity of sand dunes.
    Study of Energy Flow Between Litter and Decomposers in Aneurolepidium chinese Grassland
    Gui Ji-xun, Zhu Ting-cheng
    Chin J Plan Ecolo. 1992, 16 (2):  143-148. 
    Abstract ( 1927 )   PDF (294KB) ( 797 )   Save
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    The results of the energy flow analysis on litter and decomposing organisms showed that energy to be input into litter is about 3769.42kJ/m2/a owing to plants death; the litter energy mass is about 3424.10kJ/m2; the energy consumed by decomposers is about 1141.67kJ/m2/a, 71.87% of which is used for respiration of decomposers. At present, inputing energy is more than outputing energy in the process of energy flow between litter and decomposers, energy is on accumulating stage in Aneuroplepidium chinese grassland. Energy mass stored in litter will be 11305.61kJ/m2 and in decomposers will be 1475.20kJ/m2 at steady state.
    Research of Biomass and Net Primary Productivity of Filifolium sibiricum Grassland in Eastern Neimengou
    Xing Fu, Zhu Ting-cheng
    Chin J Plan Ecolo. 1992, 16 (2):  149-157. 
    Abstract ( 2140 )   PDF (492KB) ( 954 )   Save
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    The growth dynamics of grass aboveground biomass(AB) of Filifolium sibiricum grassland was studied experimentally and shown to agree with Logistic growth with maximum value, occuring in the middle of August (198.15 g·m-2 DM). After germinating the herb F. sibiricum grew quickly, the growth time needed to reach the maximum AB were less than other forbs species.There was a significant or extremily significant positive correlation between precipitation, accumulated temperature (≥5℃) and the AB increase of F. sibiricium, grass and forbs. The seasonal variation of underground biomass (UB) generally showed a “U” form, the minimum UB occurred in middle of August, the maximum UB occurred in the middle of October (1608.2g·m-2DM), and it was close to that in early spring. The net primary productivity of the aboveground part was 256.74g·m-2. year, and the underground 599.51g·m-2’. year. If the litter in growing season was included, the net aboveground primary productivity was 29.57% higher than the result estimated with maximum standing crop method.
    The Model About Frequency Curve of Greening Overlay Rate——A New Method About Appraising the Level of Urban Greening
    Sun Tian-zong, Zhou Jian-hua
    Chin J Plan Ecolo. 1992, 16 (2):  158-166. 
    Abstract ( 1925 )   PDF (605KB) ( 644 )   Save
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    This is the first research on the evaluation model of the level of urban greening characterized by frequency curve of green rate with the technique of aerial remote sensing and computers. The greening level of all 12 regions over 140 streets in Shanghai city have been estimated. Problems existing in the afforestion and possible solution in these regions are derived by running the model. This model has many useages, for excample, it can be used to evaluation the greening level, design a excellent programme about greening layout as a whole, forecasting the greening development and so on. So it is a new way of evaluation of greening level.
    A Study on the Function to Purify the Wastewater Containing Silver by Ipomoea aquatica
    Pi Yu, Dai Quan-yu, Chen Yuan-gao
    Chin J Plan Ecolo. 1992, 16 (2):  167-173. 
    Abstract ( 1874 )   PDF (397KB) ( 582 )   Save
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    Results of static and dynamic simulated test to purify the waste water containing silver by Ipomoea aquatica indicated, 1) Removal rate of Ipomoea aquatica to Ag+ is higher than removal rate to [Ag(S203)2]3-,or KAg+>K[Ag(S2O3)2]3-. 2)Relation between purification rate (R) to[Ag+(S2O3)2)3- and detention time (t) is R = AeB/t(B<0). Relation between purification rate of surface (Ps)and detention time(t)is Ps=AtB(B
    Studies upon Grassland Vegetation on Coastal Sandy Soil at Wenchang County, Hainan Island
    Zheng Jian-duan
    Chin J Plan Ecolo. 1992, 16 (2):  174-186. 
    Abstract ( 1970 )   PDF (705KB) ( 756 )   Save
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    Using the data obtained with Line-point contact, an improved pointcontact method, we analysed the grassland vegetation on coastal sandy soil at wenchan County, Hainan Island. The vegetation can be divided into 14 associations, two types and six main formations or communities as follows:

    1. Tropical sedgeland on coastal sandy marsh

    1) Form. Leptocarpus disjunctus + Baeckea frutescens (including 5 Associations)

    2) Form. Philydeum lanuginosum(1 Asso. )

    2. Tropical grassland on coastal sand

    3) Form. lschaemum aristatum+Eremochloa ciliaris(1 Asso. )

    4) Form. Eremochloa ciliaris + Chrysopogon orientalis(1 ASSO. )

    5) Form. Spinifex littoreus + Vitex rotundifolia(1 Asso. )

    6) Comm. Chrysopogon aciculatus + Cymbopogon tortilis (1 Asso. )

    In these communities the sedgeland of Leptocarpus on gleyed sandy soil, and the grassland on helf-fixing and fixed sandy soil dominated by Eremochloa, Ischaemum and Cymbopogon are the largest and most representative in this area.

    Studies on Water Balance and Laws of Evapotranspiration in a Chinese Fir Plantation
    Kang Wen-xing, Tian Da-lun, Wen Shi-zhi, Chen Xiao-yong, Sheng Li-yuan
    Chin J Plan Ecolo. 1992, 16 (2):  187-196. 
    Abstract ( 2022 )   PDF (682KB) ( 991 )   Save
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    On the basis of the data collected from observation in six consecutive years water balance and evapotranspiration were studied. The results indicate that precipitation is 1065.5mm/year in the small watershed; that the crown-interception is 264.6mm/year, i.e. 24.8% of the total precipitation; that precipitation through crown is 799.82mm/year, i.e. 75.1% of the precipitation; that water stemflow is 1.08mm/year, about 0.1% of the precipitation; that water output in the form of runoff is 212.27mm/year of which the ground water is 203.00mm/year and surface runoff is only 9.27mm/year, thus total runoff coefficient is 0.199. On consecutive measurements of 6 years. The monthly change of soil moisture is great, but the change between years is only ±12.80, which is 1.2% of precipitation in the output of water from the ecosystem,evapotranspiration is greatest (866.03mm/year), which is 81.3% of precipitation. Of this amount,the evaporation crown-intercept is 264.6mm/year,about 31.6% of total evapotranspiration.

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