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Table of Content
    Volume 27 Issue 1
    10 January 2003
      
    Research Articles
    Placing our Hypotheses and Results in Time and Space(in English)
    James M. LE MOINE, CHEN Ji-Quan
    Chin J Plan Ecolo. 2003, 27 (1):  1-10.  doi:10.17521/cjpe.2003.0001
    Abstract ( 1678 )   PDF (431KB) ( 599 )   Save
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    Virtually all ecological investigations are conducted and constrained within a range of time and space. This suggests that interpretations of the results must be specific and that extrapolations must be made with caution. We present a hypothetical example illustrating temporal and spatial interactions as confounding factors in ecological research. Through a series of case studies, we illustrate the importance of placing our hypotheses, results from testing those hypotheses, and our conclusions in relevant scales of time and space. Our case studies focus on the ecological effects of scale for determining pattern-process relationships in a montane spruce-fir forest in China, modeling forest canopy structure, predicting carbon flux in forests the Pacific Northwest, USA; detecting temporal scales of variation in carbon flux and meteorological data from deciduous forests in Oak Ridge, Tennessee, USA; and formulating conclusions from a long-term soil-warming experiment of peatlands in Minnesota, USA. We recommend additional efforts for examining ecological phenomena across multiple temporal and spatial scales.

    Seasonal Nitrogen Retention in Temperate Hardwood Forests
    Matthew WARREN, ZOU Xiao-Ming
    Chin J Plan Ecolo. 2003, 27 (1):  11-15.  doi:10.17521/cjpe.2003.0002
    Abstract ( 2148 )   PDF (253KB) ( 642 )   Save
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    Over the past half century the development of ecosystem models which quantify material and energy flows through forest ecosystems have led ecologists to identify and characterize the various sources, sinks, and flux rates of mineral nutrients and how these are affected by disturbance. The “Vernal Dam" hypothesis suggests that during the early spring months when nutrient susceptibility to loss is highest, an ephemeral herbaceous community takes up nutrients in biomass as a mechanism to retain nutrients in the system. This paper evaluates evidence from several studies regarding the “Vernal Dam" hypothesis. The uptake of nutrients in plant biomass during the early spring months is highly variable across ecosystems, and microbial immobilization is a more important mechanism for retaining nutrients than traditionally thought. Suggestions are made for future research which considers the role of plants and microbes as a “Vernal Dam", and how the roles of plants and microbes change under different climatic conditions and ecosystem types.

    Comparative Analysis of Hydrological Functions of Major Forest Ecosystems in China(in English)
    LIU Shi-Rong, SUN Peng-Sen, WEN Yuan-Guang
    Chin J Plan Ecolo. 2003, 27 (1):  16-22.  doi:10.17521/cjpe.2003.0003
    Abstract ( 3815 )   PDF (322KB) ( 1683 )   Save
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    Based on case studies from nearly 20 forest ecological stations in different bioregions of China, the characteristics of eco-hydrological functions of forest ecosystems were studied in terms of canopy interception, soil-water storage and holding capacity. Annual canopy rainfall interception ranged from 134 to 626 mm, and was ranked in the descending order as follows : tropical mountain rain forest, subtropical western mountain evergreen coniferous forest, tropical semi-deciduous monsoon forest, temperate mountain deciduous/evergreen coniferous forest, cold-temperate/temperate mountain evergreen coniferous forest, subtropical bamboo forest, subtropical/tropical eastern mountain evergreen coniferous forest, cold-temperate temperate mountain deciduous coniferous forest, temperate subtropical deciduous broadleaf forest, subtropical mountain evergreen broadleaf forest, subtropical tropical south-west mountain evergreen coniferous forest, south subtropical evergreen broadleaf forest, and subtropical mountain evergreen broadleaf forest. The moisture holding capacity of litter was about two-to-five times its dry-weight, but varied with forest type. The soil non-capillary moisture capacity of forests ranged from 36 to 142 mm with an average of 89 mm. Non-capillary capacity of evergreen broadleaf forests was more than 100 mm, but was less than 100 mm in the cold-temperate temperate deciduous broadleaf and evergreen coniferous forests. From an ecosystem point of view, the soil non-capillary holding capacity counted for more than 90% of the total, followed by forest litter, which ranged from 3 to 10 mm, and canopy interception only occupied a small proportion (less than 2 mm). This indicates that forest soils play a significant role in regulating rainfall interception. The hydrological role of forest soil depends on its structure and porosity, which is further affected by litter-fall and forest vegetation on sites. There was no consistent result with respect to the relationship between forest cover and annual runoff based on paired comparison of forest watersheds or direct measurements of the same forest watershed with a change of forest cover over time. Soil surface runoff was found to increase remarkably after forest logging, in particular, after clear-cut on a large scale irrespective of forest types or regions. An appropriate thinning or tending practices, however, could reduce soil surface runoff to a certain degree in forest watersheds. With increasing precipitation, forest evapo-transpiration increased slightly, while the Relative Evapo-transpiration Ratio (RER) decreased with the RER variation ranging from 40% to 90%.

    Advances in Research on the Relationship Between Climatic Change and Tree-Ring Width
    WANG Ting, YU Dan, LI Jiang-Feng, MA Ke-Ping
    Chin J Plan Ecolo. 2003, 27 (1):  23-33.  doi:10.17521/cjpe.2003.0004
    Abstract ( 2339 )   PDF (401KB) ( 1393 )   Save
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    Photosynthetic Character and Water Use Efficiency of Different Leaf Shapes of Populus Euphratica and Their Response to Co2 Enrichment
    SU Pei-Xi, ZHANG Li-Xin, DU Ming-Wu, BI Yu-Rong, ZHAO Ai-Fen, LIU Xin-Min
    Chin J Plan Ecolo. 2003, 27 (1):  34-40.  doi:10.17521/cjpe.2003.0005
    Abstract ( 3435 )   PDF (332KB) ( 2178 )   Save
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    Populus euphratica Oliv. is an important tree species of desert riparian forest. Leaf shape of P. euphratica is variable but can be roughly classified into two types, namely poplar leaf and willow leaf. Representative leaves of these types were ovate and lanceolate respectively. In this study some standard adult plants with both ovate leaves and lanceolate leaves were selected from the Nature Reserve of Populus euphratica in Ejin Qi, Inner Mongolia (41°58′ N, 101°05′ E, 930 m a.s.l.). In this measurement, the branches were put at the same height, then live leaves were measured and their photosynthesis, transpiration and water use efficiency were compared using the LI-6400 Portable Photosynthesis System of LI-cor; the response to CO2 enrichment was also ompared. The purpose of the study was to explore the cause responsible for the changes of leaf shape of P. euphratica, so as to provide a scientific basis for the protection of P. euphratica forest. In addition, the response of the different leaf shapes to increased CO2 concentration was analyzed and the possible effects of climatic changes on the growth of P. euphratica were predicted. The results showed that under present atmospheric CO2 concentration (350 μmol·mol-1) and 1 000 μmol·m-2·s-1 of light intensity, the net photosynthetic rates (Pn) of ovate leaves (leaf blades of adult tree) (A) and lanceolate leaves (lower coppica shoot leaves of adult tree) (B) are 16.40 μmol CO2·m-2·s-1 and 9.38 μmol CO2·m-2·s-1 respectively; transpiration rates (E) are 10.8 mmol H2O·m-2·s-1 and 7.98 mmol H2O·m-2·s-1 respectively; water use efficiency (WUE) is 1.52 mmol CO2·mol-1H2O and 1.18 mmol CO2·mol-1H2O respectively. Under these conditions, the light saturation and compensation points of A are 1 600 μmol·m-2·s-1 and 79 μmol·m-2·s-1 respectively, while the corresponding values of B are 1 500 μmol·m-2·s-1 and 168 μmol·m-2·s-1. When CO2 concentration reaches 450 μmol·mol-1 and 1 000 μmol·m-2·s-1 of light intensity, the photosynthetic characteristics of A and B exhibited quite different responses. The Pn of A increased by 25.6%, to 20.60 μmol CO2·m-2·s-1, whereas the Pn of B decreased by 10.0%, to 8.44 μmol CO2·m-2·s-1. The E of both A and B decreased; values were 9.11 mmol H2O·m-2·s-1 and 6.26 mmol H2O· m-2·s-1 respectively. The WUE of A and B was 2.26 mmol CO2·mol-1H2O and 1.35 mmol CO2·mol-1H2O respectively, i.e. WUE of A increased by 48.7% and WUE of B increased by 14.4%. The light saturation of A rises by 150 μmol·m-2·s-1 but light compensation point falls by 36 μmol·m-2·s-1, while the light saturation point of B falls by 272 μmol·m-2·s-1 and light compensation point rises by 32 μmol·m-2·s-1. The two types of leaf blade exhibit completely contrary responses to CO2 concentration elevation; the poplar leaves are more adapted to atmospheric CO2 concentration elevation. This study shows that the willow leaves have a lower photosynthetic efficiency and so are likely mainly used to maintain normal growth. With the growth of the tree the willow leaves can no longer support normal growth and hence poplar leaves occur. Poplar leaves have higher resistance to atmospheric drought and higher photosynthetic efficiency. They can accumulate photosynthetic products to maintain the growth of P. euphratica in extremely adverse environments and reach a higher increment. This seems to be the real cause responsible for leaf shape changes of P. euphratica from seedlings to adult trees. With the increase in CO2 concentration the photosynthetic time of willow leaves shortens and light use efficiency decreases, but poplar leaves show the opposite tendency in these two respects. When the ground water level decreases and near-surface air becomes dry, or with climate warming due to increasing atmospheric CO2 concentration, the numberof willow leaves are predicted to decrease, even disappear.

    Effect of Vanillin on Nutritient Absorbency of China fir Seedlings
    CHEN Long-Chi, LIAO Li-Ping, WANG Si-Long
    Chin J Plan Ecolo. 2003, 27 (1):  41-46.  doi:10.17521/cjpe.2003.0006
    Abstract ( 2448 )   PDF (255KB) ( 891 )   Save
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    Chinese fir (Cunninghamia lanceolata) is a dominant, native commercial tree species in South China known for rapid growth and high quality timber. Replanting this species in pure stands has resulted in extensive areas that are poorly established and have low productivity. This serious problem has attracted nationwide attention. Recent research suggests that low productivity is caused by allelopathy. According to some laboratory studies, phenolics such as vanillin extracted from Chinese fir roots, fresh leaves, and litter inhibit seed germination and growth of seedlings. When soil phenolics have a concentration higher than the threshold of toxicity they will inhibit Chinese fir growth. However, it has been unclear how the phenolics affect the Chinese fir. The purpose of this study is to determine the concentration at which vanillin develops an allelopathic effect on nutrient absorbency in Chinese fir. The effects of different concentrations of vanillin on nutrient absorbency in Chinese fir seedlings were examined using a culture solution. The mother solution (MS) was made by dissolving nutrients (49.5g NH4NO3, 57g KNO3, 13.2g CaCl2·2H2O, 11.1g MgSO4·7H2O, 5.1g KH2PO4 and 1.179g Na2 EDTA) in 1500 ml distilled water. The mother solution of 1000 mmol·L-1 vanillin was made by dissolving 15.2g vanillin in 100 ml distilled water which was then diluted to six different levels of culture solution: 10, 1, 0.1, 0.01, 0.001, and 0.000 1 mmol·L-1, each with nutrient solutions of 0.5 MS. Distilled water was used as the control. The solution was adjusted to pH 5.1 with 100 mmol·L-1 HCl or NaOH. One-year-old Chinese fir seedlings were grown in separate plastic containers and ventilated every day using an electromotor. Each treatment was replicated three times. After seven days, concentrations of NO-3, NH+4, SO42-and HPO42- ions in the culture solutions were analyzed. Results showed that vanillin at higher concentrations inhibited uptake of these ions by China fir seedlings. The concentrations of residual NO-3 ion in the culture solution with vanillin at 10 mmol·L-1 and 1 mmol·L-1 were 5 704% and 1 561% higher than that in the control, respectively, indicating that vanillin could significantly inhibit uptake of NO-3 ion (p<0.01). At a vanillin level of 10 mmol·L-1, NO-3 ion in the culture solution was even greater than that at the beginning of the treatment. It appears that in the presence of vanillin the roots of Chinese fir seedlings produced a net output of NO-3 ion. The higher the concentrationof vanillin in the culture solution the more the nutrient ions remained in culture solution. This suggests that vanillin reduces the absorptive capacity of Chinesefir roots. The concentrations of residual NH+4 ion in the culture solution with vanillin at concentrations of 10 mmol·L-1 and 1 mmol·L-1 were 29.9% and 11.6% higher, respectively, than in the control. That is, the uptake of NH+4 by Chinese fir roots was lower in culture solution with vanillin than in the control, suggesting that vanillin significantly (p<0.05) inhibited the uptake of NH+4 ion. At concentrations of 10 mmol·L-1 and 1 mmol·L-1 vanillin, the residual SO42- in solution were 557.4% and 1 026.2%, respectively, greater than that in the control, indicating that vanillin significantly (p<0.01) reduced the uptake of SO42- ion.Using the culture solution with a vanillin concentration of 10 mmol·L-1,the residual HPO42- ion was 310.5% greater than that in the control. At the vanillin concentration of 0.01 mmol·L-1 the residual HPO42- ion was 32.5% lower than in the control. This suggests that 10 mmol·L-1 vanillin could significantly (p<0.01) inhibit uptake of HPO42- by Chinese fir seedlings, and that 0.01 mmol·L-1 vanillin could significantly accelerate uptake of HPO2-4 ion. The activity of the root system of Chinese fir seedlings was inhibited by vanillin. culture-solutions containing vanillin at 10, 1, and 0.1 mmol·L-1 activity of the root system was reduced 78.8%, 51.6% and 33.1%, respectively, compared with the control, indicating that vanillin significantly inhibited activity of the root system of Chinese fir seedlings. Lower activity of the root system decreased absorptive ability resulting in lower seedling growth. We conclude that vanillin at specific concentrations in the soil might produce allelopathic effects on Chinese fir seedlings by decreasing activity of the root system, resulting in inhibition of uptake of NO-3, NH+4, SO42- and HPO42- ions.

    Physiological Adaptation of the Invasive Plant Solidago canadensis to Environments
    GUO Shui-Liang, FANG Fang
    Chin J Plan Ecolo. 2003, 27 (1):  47-52.  doi:10.17521/cjpe.2003.0007
    Abstract ( 3867 )   PDF (255KB) ( 1725 )   Save
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    Exotic weeds have caused serious harm to crop production, orchards, lawns, natural environments and biodiversity in China. Studies on the physiological and ecological characteristics of newly introduced exotic weeds are of practical significance in the predication of their potential distribution areas and their habitats. Knowledge of the physiological response of exotic weeds in stressful environments is also useful in their integrative management. Solidago canadensis, a perennial plant originating from North America, was introduced into China as a horticultural plant in the 1970s. In east China, Solidago canadensis is mainly distributed in the areas along the Shanghai-Nanjing and Shanghai-Hangzhou railways. Solidago canadensis has caused damage to crops in dry fields, impeded the recovery of vegetation in abandoned fields, and was also recorded as one of the most common weeds in suburbs of Shanghai. Therefore, Solidago canadensis has become an invasive weed. In order to understand the adaptive characteristics of Solidago canadensis to invasive environments and predict its potential distributive regions, physiological traits, including the contents of free proline, MDA and soluble sugar, POD activity and POD isozymogram, under different stresses were determined. POD isozymes were examined by polyacrylamide gel electrophoresis, and their isozymograms were analyzed by using “Image Master to Lallab” software. The results show: 1) MDA content of Solidago canadensis treated with 0.00, 0.02 and 0.05 mol·L-1 NaCl solutions are 5.76, 7.29 and 8.06 μmol·g-1 FW respectively, increasing with the elevation of the concentration of NaCl in soil; 2) MDA content of the individuals planted in loamy soils, sandy soils and clay soils is 2.46, 3.25 and 3.96 μmol·g-1 FW respectively, and their POD activity is 4.12, 3.40 and 3.04 △OD min-1·g-1 FW respectively, that is to say, the individuals planted in loamy, sandy soils have lower concentrations of MDA and higher activity of POD than those in clay soil; 3) For the individuals planted under 5 ℃, 25 ℃ and 38 ℃, their soluble sugar content is 1.24%, 1.09% and 0.61% respectively, their free proline content is 53.80, 15.00 and 116.12 μg·g-1 FW, respectively, their POD activity is 2.80, 2.70 and 2.18 △OD min-1·g-1 FW respectively, and their MDA content is 7.35, 5.29 and 7.86 μmol·g-1 FW respectively. Individuals grown 38 ℃ had higher concentrations of MDA, free proline and soluble sugar, and lower POD activity; 4) Compared with plants grown at 25 ℃, the POD isozymogram of Solidago canadensis grown at 38 ℃ is obviously different, while the isozymogram from plants grown at 5 ℃ is similar, indicating that low temperature has little effect on Solidago canadensis. Based on the results above, the following conclusions could be drawn: 1) The well-aerated, slight acid soils with low NaCl concentration are suitable for the growth of Solidago canadensis; 2) higher temperatures are more harmful to Solidago canadensis than low temperatures. It is possible for Solidago canadensis to spread in subtropical and temperate areas in China. Additionally, Solidago canadensis can easy build its clones through its root system.

    Response of the Eco-physiological Characteristics of Some Plants Under Blown Sand
    YU Yun-Jiang, SHI Pei-Jun, LU Chun-Xia, LIU Jia-Qiong
    Chin J Plan Ecolo. 2003, 27 (1):  53-58.  doi:10.17521/cjpe.2003.0008
    Abstract ( 2592 )   PDF (304KB) ( 936 )   Save
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    Blown sand is very common in nature. In areas with frequent blown sand, especially arid and semi-arid areas, blown sand not only buries highways and railways but also poses a threat to the sustainable use and development of plant resources. In the past, researchers have conducted many studies of sand-burying and wind erosion, but there are few studies on the effect of blown sand on plant eco-physiology. The nature of the influence of blown sand on the eco-physiological characteristics of plants is an important question. Though scientists have observed and studied some effects of wind on morphological characters and transpiration ratios the effects of blown sand on the net photosynthetic rate, water use efficiency etc. of plants are unknown. In this paper, based on experimental methods we showed relations between different blown sand conditions and some ecophysiological characteristics in plants, and revealed adaptability of experimental plants to blown sand by observing the change of hotosynthesis and water use efficiency in plants. In this paper, using a field wind tunnel, the effects of blown sand on the growth characteristics of some sand-fixing plants (Eragrostis poaeoides Beauv.,Agriophyllum squarrosum, Bassia dasyphylla Kuntze,Caragana korshinskii Kom., Artemisia ordosica Krasch,Reaumuria soongorica Maxim, Ammopiptanthus mongolicus Cheng f., Hedysarum scoparium L.,Robinia pseudoacacia L.) were studied under different wind conditions including different wind velocities (5.9, 7.9, 9.9, 14 m·s-1 etc.) and blowing intervals (2 d, 4 d, 9 d), and some eco-physiological parameters were measured. The results showed: 1) Both wind and wind-sand current made net photosynthetic ratio (Pn) decrease and transpiration ratio (E) rise, and thus made water use efficiency (WUE) decrease. 2) The larger the wind velocity was or the shorter the blowing interval by wind-sand was, the larger the reduction in Pn; the effect of wind-sand current on the above index was greater than the effect of pure wind. The more fierce the wind-sand menace to the plants was, the less the substance accumulation was, and thus the more slowly the plant grew in height; 3) Wind-sand current aggravated desiccation of plants, due to the reduction in WUE. Meanwhile sand-fixing plants have adaptability to wind-sand current. The shrubs showed more adaptability to wind-sand current than the grasses. According to the change of WUE in experimental plants under blown sand conditions, the adaptability of experimental shrubs to blown sand ranks as follows: Reaumuria soongorica >Ammopiptanthus mongolicus > Caragana korshinskii>Artemisia ordosica >Hedysarum scoparium > Robinia pseudoacacia. This ranking corresponds with the order in their capability of resisting drought. (4) The affecting capability of the blown sand on different plants is different. In this experiment, the change in Pn and WUE for grasses is more than shrubs, and the change for Artemisia ordosica is less than for Agriophyllum squarrosum under higher velocity.

    The Characteristics of Litterfall of Abies Fabri Forests on the Gongga Mountain
    LUO Ji, CHENG Gen-Wei, SONG Meng-Qiang, LI Wei
    Chin J Plan Ecolo. 2003, 27 (1):  59-65.  doi:10.17521/cjpe.2003.0009
    Abstract ( 1912 )   PDF (229KB) ( 820 )   Save
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    Litterfall and nutrient return patterns were studied in three successional stages of Abies fabri forests on the east slope of Gongga Mountain. The rate of litterfall showed an increasing trend while succession proceeded. The seasonality of litterfall of Abies fabri mature and young forests was unimodal, with a distinct peak in October and a lean period from May to June, while the seasonality of litterfall of Abies fabri middle age forest was a binomial curve, with peaks in May and October. Annual litterfall of mature, middle age and young forests averaged 2 809.925, 2 787.086, and 2 043.585 kg·hm-2·a-1, respectively. Leaf litter constituted 72.79%-77.66%of annual litterfall in all three forests. In all forests, the miscellaneous fraction made only a very small contribution 23%-3.54%) to the total litter production. The lichen and moss fraction also made a contribution (1.62%-5.19%) to the total litter production; this is an obvious feature of Abies fabri forest. Nutrient concentrations varied significantly between forests and litter fractions. Nutrient (N) concentrations were highest in the leaf litter, but litter concentration of mineral elements was lower than that of fresh foliage, due to resorption during senescence. The rate of N, P and K mass in the leaf that was resorbed during senescence showed an increasing trend in the order: middle age forest >mature forest > young forest. Nutrient (N, P, K) returns of the mature, middle age and young forests were 34.850, 33.917, and 42.571 kg·hm-2·a-1, respectively. There are many differences of the litterfall and nutrient return patterns between Abies fabriforests and other types of conifer forests in China, but there also exist some similarities with Abies forests in the Northwest of America.

    Allozyme Diversity in Natural Populations of Betula Alnoides from Guangxi, China
    ZENG Jie, WANG Zhong-Ren, ZHOU Shi-Liang, ZHENG Hai-Shui, BAI Jia-Yu
    Chin J Plan Ecolo. 2003, 27 (1):  66-72.  doi:10.17521/cjpe.2003.0010
    Abstract ( 2104 )   PDF (282KB) ( 1184 )   Save
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    Betula alnoides is a valuable tree species in tropical and warm sub-tropical areas in South-east Asia and China. Its natural populations have become increasingly fragmented due to over-harvesting for local economic development in Guangxi, China during the last decade. Thus conservation of its genetic resources is of urgent need for future genetic improvement programs and sustainable management. Here, the allozyme diversity of Betula alnoides was analyzed by starch gel electrophoresis with improved Tris-maleate extraction buffer. Young leaves were collected from seedlings grown by seeds from 11 natural populations in Guangxi, China. Of the 21 enzymes tested, 10 (AMP, FBA, GDH, G6PD, IDH, MDH, PGD, PGI, PGM and SKD) could be consistently resolved and scored. Among 15 interpretable loci there were 9 polymorphic loci (0.95 criterion); the remaining 6 loci were monomorphic. High genetic variability was quantified by three indices: percentage of polymorphic loci (P), mean number of alleles per locus (A) and mean expected heterozygosity (He). The observed values of these indices were 55.2%, 2.00 and 0.204 respectively, all of which were higher than the averages of outcrossing wind-pollinated woody species (53.0%, 1.84 and 0.154, summarized by Hamrick et al., 1989). Ho was always higher than He in the 11 populations, indicating an excess of heterozygotes, which perhaps resulted from a higher probability of survival for heterozygous individuals. No significant correlation was detected between the genetic diversity and geographic variables of these populations. It is worth noting that populations 2 (Dizhou, Jingxi County), 5 (Haicheng, Pingguo County) and 9 (Zhemiao, Tianlin County) should be selected and managed as in-situ conservation localities, because they contain a majority of alleles and high levels of genetic diversity. The method and findings in this study could be applied in further studies on the genetic structure, diversity and genetic improvement of this species and other species of the genus Betula. Betula alnoides is a valuable tree species in tropical and warm sub-tropical areas in South-east Asia and China. Its natural populations have become increasingly fragmented due to over-harvesting for local economic development in Guangxi, China during the last decade. Thus conservation of its genetic resources is of urgent need for future genetic improvement programs and sustainable management. Here, the allozyme diversity of Betula alnoides was analyzed by starch gel electrophoresis with improved Tris-maleate extraction buffer. Young leaves were collected from seedlings grown by seeds from 11 natural populations in Guangxi, China. Of the 21 enzymes tested, 10 (AMP, FBA, GDH, G6PD, IDH, MDH, PGD, PGI, PGM and SKD) could be consistently resolved and scored. Among 15 interpretable loci there were 9 polymorphic loci (0.95 criterion); the remaining 6 loci were monomorphic. High genetic variability was quantified by three indices: percentage of polymorphic loci (P), mean number of alleles per locus (A) and mean expected heterozygosity (He). The observed values of these indices were 55.2%, 2.00 and 0.204 respectively, all of which were higher than the averages of outcrossing wind-pollinated woody species (53.0%, 1.84 and 0.154, summarized by Hamrick et al., 1989). Ho was always higher than He in the 11 populations, indicating an excess of heterozygotes, which perhaps resulted from a higher probability of survival for heterozygous individuals. No significant correlation was detected between the genetic diversity and geographic variables of these populations. It is worth noting that populations 2 (Dizhou, Jingxi County), 5 (Haicheng, Pingguo County) and 9 (Zhemiao, Tianlin County) should be selected and managed as in-situ conservation localities, because they contain a majority of alleles and high levels of genetic diversity. The method and findings in this study could be applied in further studies on the genetic structure, diversity and genetic improvement of this species and other species of the genus Betula.

    Effect of Atmospheric Phenomena Factors on the Milling Quality and the Appearance Quality of Medium India Hybrid Rice During the Period from Full Heading to Maturity
    XU Fu-Xian, ZHENG Jia-Kui, ZHU Yong-Chuan, WANG Gui-Xiong
    Chin J Plan Ecolo. 2003, 27 (1):  73-77.  doi:10.17521/cjpe.2003.0011
    Abstract ( 1855 )   PDF (172KB) ( 875 )   Save
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    Many studies on the susceptibility of grain quality to atmospheric factors during the period from full heading to maturity of inbred rice have been conducted, but there are few for hybrid midseason-rice. The grain yields of hybrid midseason-rice have

    Study on Morphological Variation of Phragmites Australis in the Yellow River Downstream Wetland
    ZHANG Shu-Ping, WANG Ren-Qing, ZHANG Zhi-Guo, GUO Wei-Hua, LIU Jian, SONG Bai-Min
    Chin J Plan Ecolo. 2003, 27 (1):  78-85.  doi:10.17521/cjpe.2003.0012
    Abstract ( 2315 )   PDF (273KB) ( 978 )   Save
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    In this paper, the level and pattern of morphological variation of Phragmites australis in the Yellow River downstream wetland has been studied when water and salinity were considered as dominant ecological factors. A total of 14 populations from estuary to inland along the Yellow River and one freshwater population from Nanyang Lake were selected for study. The basal diameter, height, leaf length and width in the middle of stem, internode length in the middle of stem, internode amounts and panicle length of 30 plants from every population were recorded and analyzed. Results showed that the decreasing arrangement of CV (Coefficient of variation) within population of 7 morphological characters was from internode length in the middle of stem(0.2846), leaf width in the middle of stem (0.2536), panicle length (0.2449), leaf length in the middle of stem (0.2085), basal diameter (0.1875), internode amounts (0.1763) to height (0.1657). The variability of 7 morphological characters among populations was arranged decreasingly from height, leaf length in the middle of stem, internode length in the middle of stem, leaf width in the middle of stem, basal diameter, internode amounts to panicle length. Distinct morphological differentiation was observed mainly among BZH population, freshwater populations and saltwater populations, and all 7 morphological characters were significantly correlated with the combined factors of water and salinity. According to the pattern of morphological differentiation, the P. australis populations in investigated area could be divided into three ecotypes, including saltwater reed, freshwater reed and giant reed.

    The Responses of Momordica Charantia at Different Modular Levels to the Changes of Support Diameter
    TAO Jian-Ping, ZHONG Zhang-Cheng, HUANG Lin
    Chin J Plan Ecolo. 2003, 27 (1):  86-92.  doi:10.17521/cjpe.2003.0013
    Abstract ( 1928 )   PDF (316KB) ( 789 )   Save
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    The morphological plasticity of plants occurs due to the changes of modular quantity dynamics, modular patterns and modular morphologies. Climbing plants differ from non-climbing and self-supporting plants in many growth characteristics, which mainly result from biomechanical constraints. The morphology and growth of climbing plants may be affected by external supports to a large extent. External supports are important resources and determine the strategies which climbing plants use to obtain maximum sunlight. The object of this study is to describe the effects of external support diameter on growth, biomass allocation and morphological plasticity of herbaceous climbing plants at different modular levels.Three questions are addressed in this study: 1) Do plants have growth, biomass allocation and morphological plasticity responses at different modular levels on different external support diameters? 2) If so, what is the difference between the various modular levels? 3) What is the meaning of those responses on climbing plants to search and locate the external support? The garden experiment was carried out in the Ecological Garden of Southwest China Normal University with a perennial herbaceous climbing species-Momordica charantia. On 6 May 2000, the seedlings of M. charantia with the same size were planted in 40 figuline containers filled with cultivated soil, one seedling per pot. External supports were made of iron line covered with PVC at the beginning of the experiment. All plants were divided into four groups, and each group had supports with 2 mm, 4 mm, 8 mm, 12 mm and 16 mm in diameter, respectively. Each plant was supplied with the same quantity of water and nutrient during the experiment. From 7 June to 6 July, the individual’s growth conditions and branch numbers were recorded at 10 day intervals. All individuals were harvested at 25 August and divided into main stem and shoot, the following parameters were measured separately: a) internode length, b) internode diameter, c) petiole length, d) single leaf area, e) the number of primary branch and f) second branch and the distance from primary branch to base of main stem. The individuals were separated into root, main stem, shoot, lamina, petiole, flower and fruit, and cleaned by tap water and oven-dried for 72 h at 84 ℃, then weighed separately. The main results of this study were as follows: 1) The climbing efficiency of plants was significantly affected by support diameters with climbing efficiency reducing with increase in support diameter. The climbing growth rate of plants on the 2 mm, 4 mm, 8 mm, 12 mm and 16 mm supports were 3.00, 3.00, 2.13, 0.88 and 0.75, respectively; 2) The changes of support diameters did not affect the timing of shoot occurring but significantly affected the shoot numbers and shoot sites along stem. The first primary shoot of all individuals sprouted between 13 June and 17 June, the means of primary shoot numbers on the 2 mm, 4 mm, 8 mm, 12 mm and 16 mm supports were 12.3,10.0,11.3,14.3 and 14.6, respectively; 3) The individuals had higher sensitivity to the changes of support diameter than those of shoots. Plants showed powerful capacity of searching external supports when they encountered the large diameter supports. In this case, the stem extension slowed, specific stem length enlarged, shoot number and branching ratio increased, shoot length and petiole length prolonged, while R/S ratio decreased. The biomass accumulation of individuals was affected slightly by different support diameters, the biomass of individuals grown on the 2 mm, 4 mm, 8 mm, 12 mm and 16 mm supports were 43.56 g, 47.29 g, 34.32 g, 50.46 g and 31.44 g, respectively; 4) The changes of external support diameters had no significant effect on morphological characteristics and biomass characteristics of shoots; 5) The changes of morphology, biomass allocation and shoot behavior of individuals were the responses of the climbing plants to the availability of external supports, which would help the individuals to enhance the capacity of foraging supports.

    Effects of Environmental Factors on Azimuth Distribution in Cryptomeria Tree Rings in
    DENG Zi-Wang, QIAN Jun-Long, TU Qi-Pu, PU Pei-Min, HUANG Chun-Pu, KE Shan-Zhe, HUANG Yao-Sheng, TANG Jin-Song, KE Xiao-Kang
    Chin J Plan Ecolo. 2003, 27 (1):  93-98.  doi:10.17521/cjpe.2003.0014
    Abstract ( 3036 )   PDF (274KB) ( 784 )   Save
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    The characteristics of azimuth distribution of in Cryptomeria fortunei tree rings in Tianmu Mountain regions was studied by means of statistic methods including variance analysis,composition analysis and empirical orthogonal function (EOF) analysis. The effects of environmental factors on the interannual alternation of azimuth distribution patterns were also investigated by correlation analysis. The results showed that in Cryptomeria tree rings aried along with both azimuth and time significantly. The variation along with azimuth can be represented by four basic azimuth distribution types (denoted by Types 1,2,3 and 4). Type 1 : the anomalies in all azimuths are positive, and they are >0.5 in north (N), west (W), southwest (SW) and south (S) and between 0.2-0.4 in the other four directions. Type 2 : also with positive anomalies in all azimuths as in Type 1, but the anomalies are in the interval 0.2-0.4 in most directions except for N (<0.2). Type 3 : the anomalies are about -0.4 in the NW and NE, and in the range of -0.3 to -0.2 in all other directions. Type 4 : the anomalies in NE, E and SE directions are near 0.0 while at 0.1, in the NW, -0.2 in N, and -0.3 in the other 3 directions. The variation with time can be presented by either the alternation of the four basic types or by the first two principle components (PC1 and PC2) of the eight-azimuth time-series. Furthermore, the PC1 significantly positively correlated with the total precipitation for the period from January to March and negatively correlated with the total rainfall for the period from August to December of the last year. There was a positive correlation between average temperature for the period from August to January along the PC2 axis. The azimuth distribution type varies under different climatic conditions. The favorable environmental factors for types 1 and 2 include: 1) shortage of precipitation from August to December of the preceding year; 2) richness of rainfall from January to March, and 3) lower temperature from March to July and higher (lower) temperature from last August to present January. The opposite climatic conditions were favorable to types 4 and 3. This phenomenon suggests that the azimuth distribution types may contain environmental information, which could be used to established more detailed historical climate data by both averaged in whole tree ring and its azimuth distribution type time series. 

    Changes in Plant Competition with the Development of Gaps
    XIANG Yan-Ci, PENG Shao-Lin, CAI Xi-An, REN Hai, ZHOU Hou-Cheng
    Chin J Plan Ecolo. 2003, 27 (1):  99-102.  doi:10.17521/cjpe.2003.0015
    Abstract ( 2216 )   PDF (183KB) ( 894 )   Save
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    Juvenile plants in a community usually compete with the established vegetation within that community. In general, plants are likely to compete for three kinds of ssential resources: photosynthetically active radiation, water and essential nutrients. After the formation of treefall gaps, the competition between plants in gaps and in adjacent understory may change accordingly. Two fundamental questions are how the intensity of competition on juvenile plants changes with the development of gaps and whether the intensity of competition on different species is different or not. We used a field experiment to measure the intensity of competition on juvenile trees in a mixed forest community with infertile soil on an island in Southeastern China. We separated competition into its above- and belowground components in the field. We reduced aboveground competition by felling large trees to create three treefall gaps, and removed belowground competition by trenching. Thus we created three neighborhood treatments: with roots of neighbors only, with shoots of neighbors only and with no neighbors. Seedlings of three tree species were transplanted into the three gaps with and without trenches cut around the gaps. These species included the two exotic species Eucalyptus urophylla S.T.Blake and Acacia auriculaeformis A.Cunn., and one native species, Schima superba Gardn. et Champ. We measured the biomass, the relative growth rate, and competition intensity of seedlings of the three species over two years. Results based on the average of the three species showed that the intensity of above- and belowground competition on the seedlings of the three species increased gradually with the development of gaps. The intensity of aboveground competition was greater ofr the tow exotic species than that for the native. However, for the native species, the intensity of belowground competition was greater than that for the tow exotics. The relative growth rates of seedlings of the three species with roots of neighbors only and with shoots of neighbors only were all less than with no neighbors. The results showed that the competition of shoots and roots of neighbors in gaps imposed negative impacts on the growth of the three species. The impacts differed between exotic and native species.

    Impact of Disturbance of Planting Amomum villosum in Tropical Seasonal Rainforest on Forest net Primary Productivity in Xishuangbanna
    ZHENG Zheng, FENG Zhi-Li, GAN Jian-Min
    Chin J Plan Ecolo. 2003, 27 (1):  103-110.  doi:10.17521/cjpe.2003.0016
    Abstract ( 1861 )   PDF (331KB) ( 950 )   Save
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    Xishuangbanna, located in south Yunnan, southwest China, is the northern border of the tropical zone. It maintains large areas of tropical rainforest called tropical seasonal rainforest. Like most tropical rainforests all over the world, these tropica

    Pollination Biology of Ficus Auriculata Lour.in Tropical Rainforest of Xishuangbanna
    PENG Yan-Qiong, YANG Da-Rong, ZHOU Fang, ZHANG Guang-Ming, SONG Qi-Shi
    Chin J Plan Ecolo. 2003, 27 (1):  111-117.  doi:10.17521/cjpe.2003.0017
    Abstract ( 2399 )   PDF (286KB) ( 1139 )   Save
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    Ficus auriculata Lour. is a widely distributed and common species in the tropical rainforests in Xishuangbanna, China. The pollination of Ficus auriculata is done by Ceratosolen emarginatus Mayr, their unique symbiotic associates. The fig-pollination wasps cannot develop anywhere except in the host syconia, and so both are highly co-evolved mutualists that depended completely on each other for propagation. The present paper reported on the growing character of syconia and flowering phenology of Ficus auriculata, as well as the pollination behavior, regularity of fig visitation and pollination efficiency of Ceratosolen emarginatus based on our observations in the rainforests of Xishuangbanna, southern Yunnan, China. Ficus auriculata is a dioecious plant that bore fruit all year round in the population, with two fruit-bearing peaks on the female trees and one fruit-bearing peak on the male trees. The male trees produced pollen and provided fig wasps with havens, while the female trees produced fig seeds after pollination by fig wasps. The reproduction of Ceratosolen emarginatus varied with foundress number of females entering into a syconium in different seasons. The fruit-bearing peaks of female trees appeared from April to June and from September to November each year, and foundress number per syconium also peaked during these periods. Male trees bore the most fruits in January, however, due to the number restriction of fig wasps, the foundress number entering into a male syconium was low; its peak was postponed between 25th of March and 10th of April, when some syconia had matured. In order to ensure reproductive success, Ficus auriculata has evolved three out-breeding mechanisms: dichogamy, gynodioecy and incompatibility of short-style female flower. Ceratosolen emarginatus visited syconia when female flowers were blossoming, and entered into the fig cavity to lay eggs or pollinate pollen. The fig wasps’ behavior of visiting syconia was controlled by temperature and humidity: the fig wasps actively visited receptive syconia when temperature and humidity varied mitigatively in the morning and afternoon; few fig wasps flew at noon. The optimum temperature was 20-24 ℃ and optimum humidity was 85%-93%. The fig wasps stopped hovering if the temperature was over 29 ℃, humidity was less than 58% or the weather was windy and rainy. The visiting peak of fig wasps appeared at different times in four seasons, it appeared at 10∶00 in spring, 7∶40 in summer, 11∶00 in autumn and 13∶00 in winter. The pollination efficiency of Ceratosolen emarginatus was examined by introducing eight, ten and fifteen fig wasps to a female syconium. The pollination ratio was the highest when mean eight fig wasps enter into a syconium. The mean percentage of seed was 50.8%. Mean seed ratio reached 37.2% if only four foundresses pollinate a syconium and 44.4% with ten foundresses. The result showed no difference with natural syconium of the same foundress number.

    Structure and Quantitative Features of Aquatic Plant Communities in the Hanjiang River
    WU Zhong-Hua, YU Dan, WANG Dong, XIA Sheng-Lin
    Chin J Plan Ecolo. 2003, 27 (1):  118-124.  doi:10.17521/cjpe.2003.0018
    Abstract ( 2153 )   PDF (288KB) ( 1136 )   Save
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    The Hanjiang River is not only the largest tributary of the Yangtze River, but also the most important objective enforced by the project of transferring water from South-China to North-China. Research about aquatic plant communities has not yet been reported. During the period of 1998_2000, theories and methods about plant community researches were adopted and field studies on the structure and quantitative features of aquatic plant communities were carried out in six cities along the Hanjiang River. The results indicated that the horizontal structure of communities in the upper and lower reaches of the Hanjiang River showed a patchy distribution which differed from the apparent uniform or strip distribution in lake or pond systems. The vertical structure of the biomass of communities in the upper reach was mainly focused in the submerged layer, while the floating layer and emergent layer were often undeveloped or lacking. However, in the middle reach the communities usually showed a complete and developed vertical structure. In the lower reach there were only one or two layers, and the biomass of communities was mainly concentrated in the floating layer or emergent layer. The submerged layer was comparatively undeveloped and contributed little to the communities’ biomass. In addition, the quantitative features of communities were analyzed. The study showed that the composition, structural developments and quantitative features of the community were significantly different with each spots. Water level, water flow, the characteristics of substrates, and human interference were regarded as the main factors that resulted in the difference of distribution patterns and growth form of the communities.

    Relationship Between Species Richness and Productivity in an Alpine Meadow Plant Community
    DU Guo-Zhen, QIN Guang-Lian, LI Zi-Zhen, LIU Zheng-Heng, DONG Gao-Sheng
    Chin J Plan Ecolo. 2003, 27 (1):  125-132.  doi:10.17521/cjpe.2003.0019
    Abstract ( 2228 )   PDF (329KB) ( 1507 )   Save
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    There has been a rapidly increasing interest in the effects of species richness on ecosystem productivity. In order to search for a general species richness-productivity pattern and find the mechanisms underlying the pattern, ecologists have undertake

    Stomatal Densities and Distributions of Spring Wheat Leaves Under Different Planting Densities And Soil Moisture Levels
    ZHANG Xiao-Yan, YANG Hui-Min, HOU Zong-Dong, WANG Gen-Xuan
    Chin J Plan Ecolo. 2003, 27 (1):  133-136.  doi:10.17521/cjpe.2003.0020
    Abstract ( 2278 )   PDF (164KB) ( 1274 )   Save
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    Spring wheat (Triticum aestivum L.) was grown in five planting densities (1, 10, 100, 1 000 and 10 000 individuals·m-2) and in two soil moisture levels (80% and 40% soil water capacity ). Stomata were counted and measured. The planting densities affected stomatal densities and distributions. Stomatal densities increased as the planting densities changed from 1 to 1 000 individuals·m-2, and decreased significantly at higher planting densities (10 000 individuals· m-2). The maximum stomatal density was found n the leaf base, while the minimum in the leaf apex. Stomatal distribution became more symmetrical with the increase of planting densities. Similar but more pronounced changes in stomatal densities and distributions were found in the drought stressed plants. Therefore, it is concluded that the changes in stomatal densities and distributions were the result of different water conditions induced by the planting densities.

    Effects of Salt Stress on the Levels of Covalently and Noncovalently Conjugated Polyamines in Leaf Thylakoid Membrane Isolated From Barley Seedlings
    ZHAO Fu-Geng, SUN Cheng, ZHANG Wen-Hua, LIU You-Liang
    Chin J Plan Ecolo. 2003, 27 (1):  137-140.  doi:10.17521/cjpe.2003.0021
    Abstract ( 2389 )   PDF (161KB) ( 900 )   Save
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    When 6 days old barley (Hordeum vulgare L. cv. `Jian 4} seedlings were treated with different concentrations of NaCl for 3 days, the contents of noncovalently conjugated polyamines (PAs) in leaf thylakoid membrane were not changed under low NaCl concentration treatment, but decreased remarkably with NaCl concen tration increasing. Among three kinds of detected noncovalently conjugated PAs, Spd level was the most abundant, which accounted for 40% approximately. However, the contents of covalently conjugated PAs were gradually decreased with NaCl concentration increasing. Among three kinds of detected covalently conjugated PAs, Put level was predominant, which accounted for about 60%. The incorporation of 14C-Glu into thylakoid membrane protein was decreased strikingly by increasing salinity.

    Immerged Community:reconstruction of ecology I
    CHANG Jie, GE Ying
    Chin J Plan Ecolo. 2003, 27 (1):  141-142.  doi:10.17521/cjpe.2003.0022
    Abstract ( 1419 )   PDF (63KB) ( 765 )   Save
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