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Table of Content
    Volume 29 Issue 3
    30 May 2005
      
    Research Articles
    SURVIVAL ANALYSIS OF ABIES FAXONIANA POPULATIONS NEAR TIMBERLINE ON THE UPPER MINJIANG RIVER
    CHENG Wei, WU Ning, LUO Peng
    Chin J Plan Ecolo. 2005, 29 (3):  349-353.  doi:10.17521/cjpe.2005.0045
    Abstract ( 2189 )   PDF (570KB) ( 992 )   Save
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    Abies faxoniana forests are one of the major types of sub-alpine dark coniferous forests on the eastern Tibetan Plateau. In the mountainous areas of the upper Minjiang River, it is distributed between altitudes of 2 800-3 800 m a.s.l and usually forms the upper timberline on shaded slopes. To explore the survival status of A. faxoniana populations, ten plots (20 m×20 m) were investigated and analyzed in Gonggangling (33°02′39″ N, 103°43′11″ E). Individual ages were determined using WinDENDRO system or by counting tree branches. Time-specific life tables or vertical life table curves of survival-mortality based and hazard based age structures were drawn. The results showed that: 1) The survival curve of the population conformed to the type of Deevey-Ⅲ; 2) With an increase in the population mortality ratio and a decrease in the survival rate, the mortality ratio greatly increased in ages 0-40 years, reaching 89.7%; 3) There existed two peaks of mortality in the lifespan, one was from seedlings to young trees (0-40 years) and the other in the adult stage (180 years). It is suggested that the mortality rate of A. faxoniana seedlings is impacted most by temperature, wind, snowpack depth, water and other environmental factors.

    EFFECTS OF GAP AND UNDERSTORY EVIRONMENTS ON THE REGENERATION OF QUERCUS ALIENA VAR. ACUTESERRATA AND FAGUS ENGLERIANA
    CHEN Zhi-Gang, FAN Da-Yong, ZHANG Wang-Feng, XIE Zong-Qiang
    Chin J Plan Ecolo. 2005, 29 (3):  354-360.  doi:10.17521/cjpe.2005.0046
    Abstract ( 3222 )   PDF (632KB) ( 1046 )   Save
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    Quercus aliena var. acuteserrata and Fagus engleriana are important species in the temperate and subtropical middle-elevation mountainous areas of China. In this study, we investigated the regeneration dynamics, diameter size class distributions, and the light response curve of these two species to better understand the effects of light availability on the regeneration of Q. aliena var. acuteserrata and F. engleriana. The results showed that both species had a high abundance of seedlings in the field, but the survival rate from seedling to sapling stage was nearly zero for Q. aliena var. acuteserrata and only 6%-8% for F. engleriana. In the mixed-forest that contained both species, the population of F. engleriana showed a stable pyramidal age structure, but the size structure of Q. aliena var. acuteserrata was dominated by a few cohorts of trees that were able to establish within a short time period. From the light saturation response curve of the two-year old cohort, Q. aliena var. acuteserrata seedlings in gaps had a higher maximum photosynthetic rate (4.61 μmol·m-2·s-1) than F. engleriana (4.16 μmol·m-2·s-1) and, for the seedlings under canopy, F. engleriana had higher maximum photosynthetic rate (3.89 μmol·m-2·s-1) than Q. aliena var. acuteserrata (3.68 μmol·m-2·s-1). Moreover, seedlings of F. engleriana reached maximum photosynthetic rates with lower photosynthetic photon flux density than Q. aliena var. acuteserrata. The light induction curve indicated that both the response speed and the maximum photosynthetic rate of Q. aliena var. acuteserrata understorey seedlings were lower than that of F. engleriana, which demonstrated different competitive abilities and shade-tolerance characteristics of the two species. Resource allocation experiments showed that Q. aliena var. acuteserrata seedlings allocated more biomass to above-ground growth whereas F. engleriana seedlings allocated more biomass to under-ground growth. These results are consistent with the different light use strategies of the two species.

    THE RELATIONSHIP BETWEEN REPRODUCTIVE ALLOCATION, FRUIT SET AND INDIVIDUAL SIZE OF CAMELLIA ROSTHORNIANA IN DIFFERENT COMMUNITIES
    CAO Guo-Xing, ZHONG Zhang-Cheng, XIE De-Ti, LIU Yun
    Chin J Plan Ecolo. 2005, 29 (3):  361-366.  doi:10.17521/cjpe.2005.0047
    Abstract ( 2099 )   PDF (526KB) ( 930 )   Save
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    Camellia rosthorniana is a long-lived evergreen shrub, which is widely distributed in subtropical areas of China and occurs in many types of communities on Mt. Jinyun (29°50′ N, 106°26′ E). In the present study, reproductive allocation and fruit set (number of mature fruits/number of flower buds) of C. rosthorniana populations at three successional stages (Giant bamboo forest, mixed coniferous broadleaved forest and evergreen broadleaved forest) with different population structures and densities were compared. One 2 000 m2 plot was set up in each of the three C. rosthorniana populations. Field surveys showed that the basal diameters of the largest individuals of C. rosthorniana in the giant bamboo community, mixed coniferous broadleaved community and evergreen broadleaved community were 3.52, 5.37 and 6.44 cm, respectively. Population densities (Flowering plants) in the plots were 167, 222 and 621 for giant bamboo community, mixed coniferous broadleaved community and evergreen broadleaved community, respectively. It was also found that individuals of C. rosthorniana began to flower only after it reached a basal diameter of 1 cm. All individuals in the 1.0-1.5 cm (Basal diameter) size class in the giant bamboo community flowered, but only a proportion of individuals in the same size class flowered in the mixed coniferous broadleaved community and evergreen broadleaved community. Six reproductive individuals were randomly sampled from each size class (with 0.5cm as an interval) in each population. Reproductive allocation, based on annual production, was estimated for each size class and population. Fruit set was also estimated for each population from ten randomly selected reproductive individuals. Three hypotheses were evaluated with regard to the observed patterns of reproductive allocation. One hypothesis, that reproductive allocation patterns were a function of differences in resource availability, did not provide an explanation for our results. A second hypothesis, that reproductive allocation was negatively correlated with successional maturity of the habitat could explain the observed patterns of reproductive allocation but could not explain the differences in size structures of the three populations. The third, life history hypothesis which assumed the existence of a trade-off between current reproduction and vegetative growth and/or survival rate, could explain the differences in size structures among the three populations. Reproductive allocation increased monotonically within a range of basal area sizes only, and a parabolic, not linear, model could best delineate the relationship between reproductive allocation and plant size (indicated by basal diameter). No significant differences in fruit set among populations were detected.

    QUANTITATIVE CHARACTERS OF SEEDS AND CONES IN LARIX CHINENSIS
    WNAG Xiao-An, WANG Zhi-Gao, XIAO Ya-Ping
    Chin J Plan Ecolo. 2005, 29 (3):  367-372.  doi:10.17521/cjpe.2005.0048
    Abstract ( 2551 )   PDF (427KB) ( 705 )   Save
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    Larix chinensis is an endangered plant distributed only in the Qinling Mountains of Shaanxi Province, China. It forms pure forest stands that have important ecological functions of water and soil conservation at timberline at altitudes of 2 600 - 3 600 m. Studies on the quantitative characteristics of seeds and cones are necessary for understanding why this species is endangered. The variation among 7 quantitative characteristics of seeds and cones of Larix chinensis in different environments were examined, and the relationships between seed and cone characteristics and environmental factors were analyzed using one-way ANOVA and Pearson correlation coefficients. The results showed that characteristics of the seeds and cones in different environments were significantly different. Compared to the other populations, variance analysis indicated that there were greater numbers of seeds per cone (107.22±47.3), greater total weight of seeds per plant (25.47±6.55), greater total weight of cones per plant (217.80±157.26), greater annual weight of cones (2 021±0.44), a greater number of cones per plant (4 580±2 440.7), and a greater number of seeds per cone (72.8±5.83) in Guangtou Shan. Multiple comparison analysis demonstrated that the weight of seeds per plant, the average weight of a cone and the total weight of cones per tree were greater in small populations. The coefficient of variation of seed and cone characteristics in a population was high. The CV of the number of cones per plant was 63.47% and the weight of 1 000 seeds was 19.17%, indicating that the 7 measured characteristics of seeds and cones varied greatly within and among populations. The seed and cone characteristics showed a negative correlation with altitude, slope and slope direction and a positive correlation with age. The seed number per cone was positively correlated to annual average temperature (p<0.05) and negatively correlated to mean temperature in January (p<0.05). The size of seed was positively correlated with the total number of seeds. There was no trade-off between the size of seed and the total number of seeds.

    AGE STRUCTURE DYNAMICS OF EUPATORIUM ADENOPHORUM POPULATIONS AND ITS IMPLICATIONS FOR CONTROL
    SUN Xiao-Yu, LU Zhao-Hua, YU Xing-Jun, SANG Wei-Guo
    Chin J Plan Ecolo. 2005, 29 (3):  373-379.  doi:10.17521/cjpe.2005.0049
    Abstract ( 4843 )   PDF (590KB) ( 828 )   Save
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    The invasion of Eupatorium adenophorum has caused serious damage to natural ecosystems by suppressing native species populations in disturbed forests and pastures in southwest China. In this study, the age structure dynamics of E. adenophorum populations were examined in 20 plots (10 m × 10 m) using the Greig-Smith grid method, in Panzhihua Prefecture, Sichuan Province of China. There is no standard method for identifying the age of an E. adenophorum plants, but through careful observations of the growth characteristics of E. adenophorum over several years in Panzhihua, we found a reliable method for aging individual plants. During the coldest season of every year, the apical half of branches grown in the current year wither and die, and a pair of opposite branches expand out from the lignified half that is below the wilted top. Although it can turn out clone genet alone once the branch touches the ground. At the same time sexual propagation and vegetative reproduction of radicicolous branches carry through from year to year. That is to say, the most number of branching ranks of the same branch is likely to indicate the real age of the plant. We dug out the entire plant in each grid and counted the grade rank of each branch to determine the age of each individual plant. The results showed that the age structure of the 4 populations were similar with most individuals in the infancy (92.3%) and youth (6.4%) periods. The analysis of life tables and survival curves showed that chronological sequence of an E. adenophorum invasion was as follows: first, invasion occurred along roadside fields, followed by invasion into the margins of broad-leaved forest, then deep into broad-leaved forest, and finally into Pinus yunnanensis forest. Even under different environmental conditions, survival curves of all E. adenophorum populations belonged to the Deevey type Ⅲ pattern, and mortality of all populations showed a peak in 1-2 years old with mortality rates of 97.3%. The degree to which a population deviated from a typical curve related to the intensity of human disturbance. In general, mortality during infancy period and mature period were high (93.1% and 92.0%). The invasion time-sequence model predicts that young and mature individuals will dominate the populations at 3 and 5 years from the present. Therefore, in the Panzhihua Prefecture, we predict that E. adenophorum will become a serious problem in 3 to 5 years. Compared with populations of other invasive plants, the population of E. adenophorum has a similar break out pattern among populations. Traits promoting weediness included the ability to reproduce sexually and asexually, rapid growth from seedling to sexual maturity, and, most importantly, adaptation to environmental stress (phenotypic plasticity) and high tolerance to environmental heterogeneity.

    TREE-RING CHARACTERISTICS OF LARIX GMELINII AND PINUS SYLVESTRIS VAR. MONGOLICA AND
    WANG Li-Li, SHAO Xue-Mei, HUANG Lei, LIANG Er-Yuan
    Chin J Plan Ecolo. 2005, 29 (3):  380-385.  doi:10.17521/cjpe.2005.0050
    Abstract ( 2828 )   PDF (610KB) ( 967 )   Save
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    Dendroclimatology is one of the most important methods for monitoring and reconstructing global climate change. Variations of tree-ring growth in conifers reflect temperature fluctuations, especially in high latitude regions. Larix gmelinii and Pinus sylvestris var. mongolica are two major conifer species in boreal forests in the northernmost region of China. Densitometry was used to analyze tree-ring width and density in these two species in Mohe, Heilongjiang Province, China. Seven tree-ring variables (maximum density, minimum density, mean earlywood density, mean latewood density, earlywood width, latewood width and annual ring width) were investigated using Dendro2003 and compared with meteorological data from a weather station near the sampling site. The maximum density, mean latewood density, earlywood width, latewood width and annual ring-width in Larix gmelinii were higher than those in Pinus sylvestris var. mongolica. However, the variance among all the densitometric variables in Pinus sylvestris var. mongolica was significantly higher than that in the Larix gmelinii, but the variance of total ring width was different. Both residual chronologies of tree-ring density were significantly correlated but no significant correlations were found between the tree-ring width chronologies of the two species. The maximum temperature controlled the latewood density of both species in July and August. In addition, the latewood density of Pinus sylvestris var. mongolica was closely related to the length of the growing season. Correlation analysis also demonstrated that the annual ring widths of Larix gmelinii were sensitive to the temperature at the beginning of the growing season, but the ring widths of Pinus sylvestris var. mongolica did not have any significant climatic response. In summary, although Larix gmelinii and Pinus sylvestris var. mongolica had different tree-ring growth patterns, the tree-ring maximum density of these two species was highly responsive to temperature in the late growing season. The dendroclimatic growth characteristics of these two species have potential for reconstructing climate in this region.

    ADAPTIVE ECOLOGY OF LIANAS IN AN EVERGREEN BROAD-LEAVED FOREST OF TIANTONG NATIONAL FOREST PARK, ZHEJIANG II. CLIMBING CAPACITY AND CLIMBING EFFICIENCY
    CAI Yong-Li, SONG Yong-Chang
    Chin J Plan Ecolo. 2005, 29 (3):  386-393.  doi:10.17521/cjpe.2005.0051
    Abstract ( 2884 )   PDF (589KB) ( 867 )   Save
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    Climbing capacity and climbing efficiency of lianas were used to predict their adaptive capacity and performance in an evergreen broad-leaved forest of Tiantong National Forest Park, Zhejiang. We used internode length and number of internodes of the climbing branch and trellis size as indicators of climbing capacity. Climbing efficiency was estimated by the kind, size and quantity of trellises (tree) climbed and the horizontal areal extent of an individual liana plant. Climbing capacity was determined by twelve species of lianas that belonged to five different climbing groups, and the climbing efficiency was determined by two liana species. Climbing capacity of a liana depended on the combination of internode length and number of internodes of its climbing branch and the size of its trellis. There were large differences among lianas with different climbing mechanics in internode length and number of internodes of the climbing branch and size of trellis used. Two tendril-curled lianas (Ampelopsis cantoniensis and Smilax lanceifolia var. opaca) were characterized by having the longest internode, a moderate number of internodes and small trellis. One branch-curled liana (Dalbergia millettii) had much shorter internodes than the tendril-curled liana but a similar number of internodes and trellis size. Four adventitious root-climbing lianas (Euonymus fortunei, Hedera nepalensis var. sinensis, Trachlospermum jasminoides and Ficus pumila) and one adhesive disc-climbing liana (Parthnocissus heterophylla) had the shortest internode, the most number of internodes and the largest trellis. Four stem-twining lianas (Stauntonia leucantha, Morinda umbellata, Dioscorea cirrhosa, and Lonicera japonica) had long internodes and moderate trellis size but the least number of internodes. There were also differences in internode length, number of internodes and size of trellis among lianas with the same climbing mechanics most likely due to their different origins. Differences in internode length and number of internodes within the same plant were due to phenotypic plasticity. Phenotypic plasticity, which is controlled by both genetic and environmental factors, is a highly beneficial characteristic for adaptation to the high environmental heterogeneity of the forest. Individuals of A. cantoniensis climbed more trellis and occupied more extensive horizontal areas than individuals of D. millettii. This indicates that individuals of A. cantoniensis had greater climbing efficiency and played a more important role in the forest than individuals of D. millettii.

    EFFECTS OF WATER STRESS ON PHOTOSYNTHESIS AND CARBON ALLOCATION IN CUNNINGHAMIA LANCEOLATA SEEDLINGS
    WEI Li-Li, ZHANG Xiao-Quan, HOU Zhen-Hong, XU De-Ying, YU Xue-Biao
    Chin J Plan Ecolo. 2005, 29 (3):  394-402.  doi:10.17521/cjpe.2005.0052
    Abstract ( 3608 )   PDF (747KB) ( 986 )   Save
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    Changing the allocation of carbohydrates to various organs is a central mechanism by which plants cope with temporally or spatially varying environments. Hence, a primary objective of eco-physiological research is to understand when and how this process is affected by specific external conditions. Chinese fir (Cunninghamia lanceolata) is one of the most important timber species in Southern China due to its fast growth and good timber quality. Due to large-scale afforestation/reforestation activities, Chinese fir stands, most of which are plantations, have expanded rapidly since the 1950s, and, in particular, since the 1980s, with both the area and standing volume having more than doubled. Therefore, to understand the carbon allocation in Chinese fir in response to varying soil moisture conditions, we studied the photosynthetic response and changes in photosynthate allocation of 2-year-old Chinese fir seedlings under different water treatments. The experiment was conducted in the Subtropical Forestry Experimental Center of the Chinese Academy of Forestry located in Fengyi of Jiangxi Province. Eighty potted 2-year-old Chinese fir seedlings were grown for one growing season under two water treatments: a water stress treatment in which one third the normal water supply was applied and a control (normal water management). The net photosynthetic rate (Pn) in response to photosynthetic photo flux density (PPFD) were measured using a LI-6400 portable photosynthesis system from 8∶00 to 11∶00 on clear days in late June. Air temperature and relative humidity in the chamber were maintained at (25±1) ℃ and 70%±5%. Carbon allocation in seedlings under the two water treatments was measured in the morning of early July using a 13C pulse labeling technique. The initial CO2 concentration in the labeling chamber was about 1 000 μmol·mol-1 and each labeling lasted 40 minutes. The current-needles, 1-year old needles, branches, stems, fine roots and coarse roots were sampled on day 1, day 3, day 7 and day 21 following labeling. Samples were dried, grinded to a powder, combusted, and then analyzed on an isotope ratio mass spectrometer to measure the stable carbon isotope ratio. Our results showed that water stress did not alter the photosynthetic characteristics of Chinese fir seedlings. The δ13C values and net 13C ratio (N13CR), i.e., the ratio of the net increment of 13C to the natural total carbon, of the seedlings decreased in the water-stress treatment. The effect of water deficit on the δ13C values and N13CR in shoots was more significant than in roots. The shoot biomass under water stress was reduced remarkably, while little changes were found for root biomass. Water stress had a more significant effect on current-needles than other organs. The δ13 values, N13CR and dry weight of current-needles under water stress were lower than in the control. The more rapid decline of N13CR in current-needles of water-stressed seedlings 21 days following labeling indicated that there was an increase in the export of photosynthetic products. The growth decline of the current needles under water stress caused a decrease in leaf area resulting in a reduction in total photosynthesis. Under water stress, more photosynthetic products were transferred to belowground biomass, especially to the fine roots. As a result, carbon allocation patterns were altered and higher root:shoot ratios were found in seedlings experiencing water stress!in comparison to seedlings under conditions of normal water management.

    SEASONAL DYNAMICS OF FINE ROOT BIOMASS, ROOT LENGTH DENSITY, SPECIFIC ROOT LENGTH AND SOIL RESOURCE AVAILABILITY IN A LARIX GMELINI PLANTATION
    CHENG Yun-Huan, HAN You-Zhi, WANG Qing-Cheng, WANG Zheng-Quan
    Chin J Plan Ecolo. 2005, 29 (3):  403-410.  doi:10.17521/cjpe.2005.0053
    Abstract ( 3111 )   PDF (618KB) ( 970 )   Save
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    Fine root turnover is a major pathway for carbon and nutrient cycling in terrestrial ecosystems and most likely is sensitive to many global change factors. Despite its importance in plant C allocation, nutrient cycling dynamics and the tremendous research efforts that have been made in the past, our understanding of fine root turnover remains limited, because dynamic fine root processes associated with soil resource availability still remains poorly understood. Soil moisture, temperature and available nitrogen are the most important soil resources that impact fine root growth and mortality at both the individual root branch and ecosystem level. In temperate forest ecosystems, seasonal changes of soil resource availability will alter the pattern of carbon allocation to below ground; therefore, fine root biomass, root length density (RLD) and specific root length (SRL) vary during the growing season. Studying seasonal changes of fine root biomass, RLD and SRL associated with soil resource availability will help us understand the mechanistic controls of carbon to fine root longevity and turnover. The objective of this study was to understand whether seasonal variations of fine root biomass, RLD and SRL were associated with soil resource availability, such as moisture, temperature and nitrogen, and to understand how these soil components impacted fine root dynamics in a Larix gmelini plantation. We used a soil coring method to obtain fine root (≤2 mm in diameter) samples every month from May to October in 2002 from a 17 year old Larix gmelini plantation in Maoershan Experiment Station, Northeast Forestry University. Seventy-two soil cores (Inside diameter 60 mm; depth intervals: 0-10, 11-20, and 21-30 cm) were sampled randomly from three replicate 25 m×30 m plots to estimate fine root biomass (live and dead), and calculate root length density (RLD) and specific root length (SRL). Soil moisture, temperature, and nitrogen (ammonia and nitrate) at the three depth intervals also were analyzed in the plots. The results showed that the average standing fine root biomass (live and dead) was 189.1 g·m-2·a-1, and 95.4 g·m-2·a-1 (50%) was distributed in the surface soil layer (0-10 cm), 61.5 g·m-2·a-1 (33%) and 32.2 g·m-2·a-1 (17%) were in middle (11-20 cm) and deep layer (21-30 cm), respectively. Live and dead fine root biomass was the highest from May to July and in September, but lower in August and October. The live fine root biomass decreased and dead biomass increased during the growing season. Mean RLD (7 411.56 m·m-3·a-1) and SRL (10.83 m·g-1·a-1) in the surface layer were greater than the RLD (1 474.68 m·m-3·a-1) and SRL (8.56 m·g-1·a-1) in the deep soil layer. Root length density and SRL in May were the highest (10 621.45 m·m-3 and 14.83 m·g-1) as compared to other months, and RLD was the lowest in September (2 198.20 m·m-3) and SRL the lowest in October (3.77 m·g-1). Seasonal dynamics of fine root biomass, RLD and SRL had a close relationship with changes in soil moisture and nitrogen availability, and, to a lesser extent, temperature, as determined by regression analysis. Fine roots in the upper soil layer have a function of absorbing water and nutrients, while the main function of fine roots in the deeper soil may be water uptake rather than nutrient acquisition. Therefore, carbon allocation to roots in the upper soil layer and deeper soil layers was different. Multiple regression analysis showed that variation in soil resource availability can explain 71%-73% of the seasonal variation of RLD and SRL and 58% of the variation in fine root biomass. These results suggest a greater metabolic activity of fine roots living in soils with high resource availability, resulting in an increased allocation of carbohydrates to fine roots in resource rich soils but lower allocation to roots in soils with lower resource availability.

    SOIL RESPIRATION IN BROAD-LEAVED AND KOREAN PINE FOREST ECOSYSTEMS, CHANGBAI MOUNTAIN, CHINA
    JIANG Yan-Ling, ZHOU Guang-Sheng, ZHAO Min, WANG Xu, CAO Ming-Chang
    Chin J Plan Ecolo. 2005, 29 (3):  411-414.  doi:10.17521/cjpe.2005.0054
    Abstract ( 3127 )   PDF (491KB) ( 1000 )   Save
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    The emission of carbon from soils to the atmosphere occurs primarily in the form of CO2 as the result of soil respiration. Increased storage of carbon in soil could help offset further anthropogenic emissions of CO2, whereas a release from soil could significantly exacerbate the increase of atmospheric CO2 and reinforce the greenhouse-warming effect. Because of the enormous carbon storage in soils, even a small change in soil respiration will be equal to or even exceed the annual CO2 input into the atmosphere from land use changes or burning of mineral fuels. Thus, changes in soil respiration can have a significant positive or negative impact on atmospheric CO2 concentrations and therefore affect climate change. Controlling soil respiration potentially can abate increases in atmospheric CO2 concentrations. To understand the soil respiration dynamics of the broad-leaved and Korean pine forests at Changbai Mountain, and to provide a scientific basis for quantitatively assessing carbon source/sink relationships, soil respiration in broad-leaved and Korean pine forests at Changbai Mountain was measured using a static closed chamber method. The results indicated that the diurnal dynamics of soil respiration presented a single-peaked curve with the maximum occurring around 18∶00. The seasonal dynamics of soil respiration also showed a single-peaked curve with the maximum occurring in July during the growing season. The mean soil respiration rates during the growing season were 0.22 gC·m-2·h-1 in June, 0.32 gC·m-2·h-1 in July, 0.23 gC·m-2·h-1 in August, and 0.13 gC·m-2·h-1 in September. Increasing temperatures would accelerate the soil respiration rate. Compared to air temperatures, soil temperatures more precisely reflect the dynamics of soil respiration. More soil water in a certain range would improve soil respiration rates, but excessive water in soil would restrain soil respiration rates and decrease CO2 emission rates from the broad-leaved and Korean pine forests.

    WATER HOLDING CHARACTERISTICS OF LITTER IN PLANTATIONS IN SOUTH CHINA
    XUE Li, HE Yue-Jun, QU Ming, WU Min, XU Yan
    Chin J Plan Ecolo. 2005, 29 (3):  415-421.  doi:10.17521/cjpe.2005.0055
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    Litter characteristics, such as standing crop, water holding capacity, and proportional water holding capacity and absorption rates, were studied in plantations of Cunninghamia lanceolata, Pinus massoniana, Pinus elliottii, Acacia mangium and Eucalyptus urophylla. The dry litter standing crop of C. lanceolata plantation was the largest (6.5×103 kg·hm-2) among the five plantations, followed by the P. massoniana and A. mangium plantations (5.5×103 kg·hm-2), the P. elliottii plantation (4.1×103 kg·hm-2) and the E. urophylla plantation (4.0×103 kg·hm-2). The order of total water holding capacity of litter was C. lanceolata plantation (17.9×103 kg·hm-2) > A. mangium plantation (14.8×103 kg·hm-2) > E. urophylla plantation (14.0×103 kg·hm-2) > P. massoniana plantation (10.6×103 kg·hm-2) > P. elliottii plantation (9.8×103 kg·hm-2). The proportional water holding capacity as a percentage of the litter dry weight in E. urophylla, C. lanceolata, A. mangium, P. elliottii and P. massoniana plantations were 351%, 274%, 269%, 235% and 191%, respectively. The total water holding capacity and proportional water holding capacity of litter increased logarithmically with increasing time immersed in water. The water absorption rate of litter in E. urophylla plantation was the largest among the five plantations, medium in the C. lanceolata and A. mangium plantations, lower in the P. elliottii plantation, and lowest in the P. massoniana plantation. Water absorption rates of litter in all plantations decreased according to equation Y=a+b·t-1 with increasing time immersed in water.

    SAMPLING STRATEGY FOR PRESERVATION OF GERM PLASM FROM DAVIDIA INVOLUCRATASONG
    Cong-Wen, BAO Man-Zhu
    Chin J Plan Ecolo. 2005, 29 (3):  422-428.  doi:10.17521/cjpe.2005.0056
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    Davidia involucrata is a monotypic genus that is a relict from the tropical flora of the Tertiary Period. As a plant endemic to China, it is classified as a first-grade state protection plant. An analysis on genetic diversity and genetic variation within and among populations from five natural populations of D. involucrata was conducted using RAPD marker based on 11 polymorphic random primers. The results showed that populations of D. involucrata had rich genetic diversity, but those significant differences among populations accounted for 26% of the genetic variation. Two large provenance plots in the southeast and northwest were established for the study. Based on cluster analysis of genetic diversity of populations of D. involucrata and curve analysis of the genetic markers, we put forward a sampling strategy for the preservation of germplasm of D. involucrata. For on-site preservation, three populations should be selected for each of the following areas: Wenxian County in Gansu Province, Emeishan in Shichuan Province and Fanjingshan in Guizhou Province. Each population to be preserved should occupy a minimum 3 hm2. Off-site preservation should sample a minimum of 30 individuals from each of the following populations: Wenxian County, Emeishan and Shennongjia (in Hubei Province) and Fanjingshan for a total of 150 individuals. Individuals should be planted at a minimum space of 30 m. Also, we suggest that two off-site preservation areas should be established: one in the southeast and one in the northwest regions of China.

    SPECIES RESPONSES TO DIFFERENT TYPES OF HUMAN-CAUSEDHABITAT DEGRADATION
    LIU Hui-Yu, LIN Zhen-Shan, ZHANG Ming-Yang
    Chin J Plan Ecolo. 2005, 29 (3):  429-435.  doi:10.17521/cjpe.2005.0057
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    Habitat degradation is one of the leading causes of biodiversity losses, and there is an urgency to understand species responses to human-caused habitat degradation. Habitat degradation includes long-term sustained degradation and instantaneous destruction. Previous studies have focused primarily on the rapid or instantaneous destruction of habitats; therefore, in this paper, we compared species responses to the two different kinds of habitat degradation using an N-species competitive coexistence model. The results showed that both types of habitat degradation altered competitive relationships among strong and weak species. Our results showed that species extinctions were determined by the meta-population structure, which is in contrast to the common holding view that superior species are able to avoid extinction. In the case of instantaneous habitat destruction of a tropical forest, species pass through a phase of adaptation and then a phase of recovery; in contrast, sustained habitat degradation causes species to decay successively without recovery. Sustained habitat degradation is more propitious to species persistence over the long term as compared to instantaneous habitat destruction. Instantaneous habitat destruction of temperate forests cause species to pass through an adaptation phase, a phase of recovery, and then the population oscillates quasi-periodically at an equilibrium level through time; in contrast, sustained habitat degradation leads to species declines without recovery. Our results showed that species respond very differently to the two types of habitat degradation with species abundances declining more in gradual, sustained habitat degradation as compared to the instantaneous destruction of habitats.

    VEGETATION CLASSIFICATION OF EAST CHINA USING MULTI-TEMPORAL NOAA-AVHRR DATA
    LI Jun-Xiang, DA Liang-Jun, WANG Yu-Jie, SONG Yong-Chang
    Chin J Plan Ecolo. 2005, 29 (3):  436-443.  doi:10.17521/cjpe.2005.0058
    Abstract ( 2888 )   PDF (1115KB) ( 1129 )   Save
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    East China lies in the subtropical monsoon climatic zone and is dominated by subtropical evergreen broad-leaved forests, a unique vegetation type on earth mainly distributed in East Asia with the largest and most concentrated distribution in China. It is important to be able to monitor and estimate forest biomass and production, regional carbon storage, and global climate change impacts of these important vegetation types. In this paper, we used coarse resolution remote sensing data to identify the vegetation types in East China and develop a map of the spatial distribution of vegetation types in this region. Nineteen maximum normalized difference vegetation index (NDVI) composite images (Acquisition time span 7 months from February through August), which were derived from 10-days of National Oceanographic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) channel 1 and channel 2 observations, and an unsupervised classification method, the ISODATA algorithm, was employed to identify the vegetation types. The image was processed using principal component analysis (PCA) to reduce the dimensions of the dataset resulting in a total of 28 spectral clusters of land cover of which 2 clusters were urban/bare soil and water. The 26 remaining spectral clusters were merged into 6 vegetation types: evergreen broad-leaved forest, coniferous forest, bamboo forest, shrub-grass, aquatic vegetation and agricultural vegetation using the Chinese vegetation taxonomy system. The spatial distribution and areal extent calculated for the coniferous forests, shrub-grass, evergreen broad-leaved forests and agricultural vegetation compared well with the Vegetation Atlas of China at a 1∶1 000 000 scale. The spatial accuracy for coniferous forests, shrub-grass, evergreen broad-leaved forests and agricultural vegetation was 79.2%, 91.3%, 68.2% and 95.9%, respectively, and the area accuracy was 92.1%, 95.9%, 63.8% and 90.5%, respectively. The spatial and area accuracy of the bamboo forest was 28.7% and 96.5%, the spatial accuracy of aquatic vegetation was 69.6%, but there is great error in its area accuracy because image acquisition did not cover the full year. Our research demonstrated the feasibility of using NOAA-AVHRR to identify the different vegetation types in the subtropical evergreen broad-leaved forest zone in East China. The spatial location of the 6 identified vegetation types coincided with the actual geographical distribution of the actual vegetation types in East China.

    VEGETATION IN THE LUANHE RIVER BASIN AND SURROUNDING AREAS
    XU Qing-Hai, YANG Zhen-Jing, YANG Xiao-Lan, LI Yue-Cong, ZHENG Zhen-Hua, WANG Rui-Jun
    Chin J Plan Ecolo. 2005, 29 (3):  444-456.  doi:10.17521/cjpe.2005.0059
    Abstract ( 1991 )   PDF (1168KB) ( 689 )   Save
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    This study explored the relationship between pollen and vegetation in the Luanhe River Basin and surrounding areas (39°00′-42°00′ N and 115°40′-119°50′ E) at elevations that ranged from 0 m at the Bohai Sea to 2 082 m in the Yanshan Mountains. Airborne pollen samples were collected for two years by 2 permanent weather-vane-pollen-collectors in Caiyuan, Qian'an County. Pollen samples in the surface soil were collected from 53 locations at about 100 m elevational intervals in the Yanshan Mountains and at about 20 km intervals across the level plains between the Yanshan Mountains and the Bohai Sea. Vegetation surveys were conducted simultaneously where pollen samples were collected. Alluvial pollen samples were collected from fresh sediments in the riverbed, and, at the same time, water samples were collected from the river during the low, flood, and mean water periods. Airborne pollen assemblages generally reflected the local vegetation and corresponded with flowering patterns of the vegetation over the course of the year. Most trees flowered in the spring whereas most herbs flowered in the summer and autumn. Because no plants bloom during the winter in this region, the airborne pollen in winter was wind dispersed pollen from the soil surface and some foreign pollen. From the mountain peak to seashore, five successive palynoflora zones were identified: montane meadow, coniferous-broad-leaf mixed forest or coniferous-broad-leaf mixed forest mainly composed of coniferous trees, montane brush, alluvial plain meadow and seaside meadow or saline meadow. Correspondingly, five pollen assemblages were identified: Artemisia-Thalictrum-Pinus-Betula pollen assemblage, Pinus-Betula-Quercus-Artemisia pollen assemblage, Chenopodiaceae-Artemisia-Gramineae-Selaginella sinensis pollen assemblage, Chenopodiaceae-Artemisia-Compositae-Typha pollen assemblage and Chenopodiaceae- Artemisia -Cyperaceae- Gramineae pollen assemblage. Arboreal pollen grains were dominated by Pinus that were transported a long distance, and herbaceous pollen grains were dominated by Artemisia and Chenopodiaceae that were transported a short distance. Pollen assemblages from the river water and alluvial deposits reflected the vegetation of the river basin near where the samples were collected and the genera and proportion of pollen were related to the blooming period of the different plants. The pollen concentration in river water was positively correlated with the proportion of sand in the river water indicating that the pollen grains were carried as sedimentary particles in river. The pollen in alluvial deposits came from the vegetation in the river basin, and the pollen assemblages reflected the vegetation of the whole river basin instead of partial area. Because pollen was transported in the river water by sediment suspension, pollen sorting in the river was not apparent during low and mean water flow periods but was evident during flood periods. The alluvial pollen assemblages varied among different river flow periods.

    MONITORING LEAF CARBON AND NITROGEN STATUS IN WHEAT WITH LEAF COLOR CHARACTERISTICS
    TIAN Yong-Chao, ZHU Yan, CAO Wei-Xing
    Chin J Plan Ecolo. 2005, 29 (3):  457-460.  doi:10.17521/cjpe.2005.0060
    Abstract ( 2425 )   PDF (466KB) ( 843 )   Save
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    Non-destructive monitoring of crop carbon, nitrogen and carbon to nitrogen ratios (C/N) is important for precision fertilizer management. This research was conducted to determine the relationships of leaf carbon, leaf nitrogen, and leaf C/N ratios to post-heading leaf color (SPAD values) in wheat (Triticum aestivum) under different nitrogen and water supply levels. The results showed that leaf soluble sugar content were positively exponentially related to leaf color in the top three leaves, but there were no significant relationships between color differences or ratios among different leaf positions. Similar trends were found for leaf nitrogen status. The correlation sequence was: L1>L2>L3 (correlation coefficients were 0.92, 0.86 and 0.71 for leaf nitrogen content and 0.84, 0.77 and 0.49 for leaf soluble sugar content, respectively). The best leaf position for monitoring leaf nitrogen and carbon status was the first leaf from the top in wheat (LSSC=4.080 8e0.026 9SPADL1, R2=707 5; LNC=0.697 2e0.026 1SPADL1, R2=837 6), with a RMSE of 0.22 and 0.04, respectively, for model testing. In addition, leaf carbon to nitrogen ratios were not significantly related to leaf colors in different leaf positions but were linearly significantly related with color difference between L1 and L3 in wheat (C/N=0.071 3×(SPADL1-SPADL3)+4.459), with a RMSE of 0.07 for model testing. These results indicate that the leaf color of L1 and color differences between L1 and L3 are good indicators of leaf soluble sugar content, nitrogen content and C/N in wheat leaves.

    RESPONSE OF YIELD AND QUALITY OF WHEAT TO HEAT STRESS AT DIFFERENT GRAIN FILLING STAGES
    LI Yong-Geng, YU Zhen-Wen, ZHANG Xiu-Jie, GAO Lei-Ming
    Chin J Plan Ecolo. 2005, 29 (3):  461-466.  doi:10.17521/cjpe.2005.0061
    Abstract ( 2628 )   PDF (549KB) ( 978 )   Save
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    Changes in the yields and quality and the physiological response of winter wheat (Triticum aestivum cv. ‘Ji′nan17’ and ‘Lumai21’) grown under heat stress during different filling stages were studied. Winter wheat growing in flowerpots was transferred to temperature-controlled open top chambers (OTC) after anthesis. Heat stress treatments of 25 ℃/35 ℃ (night/day) were applied at early filling stage (1-10 days after anthesis), middle filling stage (11-20 days after anthesis), and late filling stage (21-30 days after anthesis). The controls were grown at temperatures of 20 ℃/30 ℃ (night/day). Protein accumulation rate, nitrogen accumulation and distribution, kernel weight and yield, test weight, protein composition, protein content, wet gluten content, glutenin macropolymer (GMP) content, and starch and protein quality traits were measured. The results showed that protein accumulation rate in wheat kernels grown in the 25 ℃/35 ℃ (night/day) chambers were higher than those in the control chambers (p<0.05); however, nitrogen accumulation was reduced and the nitrogen harvest index (NHI) declined under heat stress (p<0.05). There were differences in starch and protein quality responses to heat stress during the different filling stages. Protein and starch quality traits improved at the early filling stage but declined at the middle and late filling stages under heat stress; however, the protein content increased at late filling stage under heat stress. Protein content increased but kernel weight decreased under higher temperatures, which suggested that the starch accumulation rate decreased more sharply than protein accumulation rates under higher temperature. The two varieties, ‘Ji'nan17’ and ‘Lumai21’, showed similar responses to heat stress at the different filling stages.

    VARIATION IN WHEAT GRAIN QUALITY GROWN UNDER DIFFERENT CLIMATIC CONDITIONS WITH DIFFERENT SOWING DATES
    PAN Jie, JIANG Dong, DAI Ting-Bo, LAN Tao, CAO Wei-Xing
    Chin J Plan Ecolo. 2005, 29 (3):  467-473.  doi:10.17521/cjpe.2005.0062
    Abstract ( 2445 )   PDF (543KB) ( 1029 )   Save
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    Grain quality of wheat is influenced by variation in genotypes, environmental factors, management practices and their interactions. Six wheat genotypes differing in grain quality were planted at four different regional sites with different sowing dates to study the variation of yield and quality traits under different climatic conditions during grain filling. The results showed that ecological condition (E), variety (V) and their interactions (E×V) had significant impacts on grain yield, thousand kernel weight (TKW), grain protein content, wet gluten and starch content, sedimentation volume, and falling number. At the four experimental sites, sowing date (S) had a highly significant effect on yield and starch content in spite of environmental conditions. The interaction of V×S significantly affected TKW, falling number, starch content and sedimentation volume, and the interaction of E×V×S also was significant on yield, contents of wet gluten and starch and sedimentation volume. The lowest protein and wet gluten content and the highest starch content were found at the Nanjing site, the highest yield and TKW were at the Xuzhou site, the highest protein and wet gluten content and lowest sedimentation value were in Tai'an, and the lowest yield and TKW and highest sedimentation value were in Baoding. The protein, wet gluten and starch content, sedimentation value, and falling number under optimal and late sowing dates were all higher than those under early sowing dates, which produced the highest yield and TKW. For the six different genotypes, the CV of falling number was the largest and that of starch content was the smallest under different eco-sites and sowing dates. Starch content was negatively linearly correlated with mean temperature from anthesis to maturity, whereas grain yield, grain protein and wet gluten content and falling number showed a quadratic correlation. Yield and TKW showed a quadratic correlation, while protein and wet gluten content, falling number and sedimentation volume were linearly correlated to diurnal temperature differences. Grain yield and TKW showed upward quadratic equations, while grain protein content and falling number showed negative linear relationships with the total rainfall after anthesis. Also, the grain protein and wet gluten content and falling number were linearly correlated to the total number of sunshine from anthesis to maturity.

    PHYSIOLOGICAL CHARACTERISTICS OF HELIANTHUS TUBEROSUS IRRIGATED BY SEAWATER, LAIZHOU COAST, SHANDONG PROVINCE
    IU Zhao-Pu, DENG Li-Qun, LIU Ling, QI Chang-Hai, CHEN Ming-Da, XIA Tian-Xiang
    Chin J Plan Ecolo. 2005, 29 (3):  474-478.  doi:10.17521/cjpe.2005.0063
    Abstract ( 2169 )   PDF (500KB) ( 862 )   Save
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    Salt stress to plants results from both osmotic stress, due to low water potentials, and direct salt-ion injury. Salt-tolerant mechanisms of plants are mainly ion compartmentalization, osmoregulation and metabolic changes. In the past, Sigle-salt experiments were usually conducted to study salt-tolerance in plants; however, experimental results were often contradicted to field observations. To better simulate actual field conditions, we conducted a laboratory experiment to study the physiological characteristics of salt-tolerance in Helianthus tuberosus using natural seawater. Potted plants of H. tuberosus were irrigated with seawater taken from the Laizhou coast, Shandong Province, China in 2000, and diluted with freshwater at the following ratios: 0∶1 (Pure freshwater), 1∶9, 1∶4 and 1∶3. The results showed that at the end of the growing period, the yield of fresh tuber in all treatments was the same following one irrigation treatment period. However, following two irrigation treatment periods, the tuber yield in the 1∶3 treatment was much higher than in the other treatments whereas the other treatments were similar. When H. tuberosus was treated with two irrigation treatment periods, the tuber yield was greater in all saltwater treatments than in the single irrigation treatment. The photosynthetic rate of H. tuberosus was consistent with changes in the salt concentration of the surface soil. On the first or second day after irrigation, the photosynthetic rate of H. tuberosus in the controls was much higher than other treatments while there was nearly no difference in rates among treatments except for the 1∶3 treatment that had lower photosynthetic rate. After sixty days of irrigation, the greatest leaf area index (LAI) was achieved in plants irrigated with pure freshwater, LAI was the lowest in plants in the most saline treatment (1∶3 seawater:freshwater), and similar in the other two treatments.

    CONSIDERATION OF SOIL ECOLOGICAL PROCESSES IN RESTORATION AND SUCCESSION
    ZHU Wei-Xing
    Chin J Plan Ecolo. 2005, 29 (3):  479-486.  doi:10.17521/cjpe.2005.0064
    Abstract ( 2418 )   PDF (472KB) ( 618 )   Save
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    The dominance of human society on earth is putting tremendous pressure on the earth's ecosystems for resources and waste assimilation. Conserving remaining “unexploited” natural ecosystems and restoring degraded ecosystems is a necessity for the long-term sustainability of humankind. Structurally, soil is the foundation of all terrestrial ecosystems and affects every ecosystem function. Unfortunately, degradation of soil by human activities is common. Understanding changes in soil microbial and invertebrate communities, organic matter accumulation, and how key biogeochemical cycling of nutrients are changed during ecosystem restoration is essential. Ecosystem restoration shares many similarities with natural succession, and therefore can benefit from the rich ecological understanding of the functional and structural changes that take place during succession. However, unlike naturally occurring succession, ecosystem restoration is manipulated through human intervention. Management decisions in restoration, including plant selection, site selection with consideration of soil parent material, topography and local climate, as well as fertilization, irrigation and other human interventions, heavily influence soil formation and soil processes, and thus affect successional trajectories and restoration. To make restored systems self-sustainable, strategies addressing short-term nutrient supply for quick plant growth and long-term soil development, and those promoting positive plant-soil feedbacks are needed. Not only is successful restoration an “acid test” of our current ecological theories, but it also contributes to the future development of our scientific discipline; thus it is both a challenge and an opportunity for professional ecologists.

    BVOCs EMITTED FROM PLANTS OF TERRESTRIAL ECOSYSTEMSAND THEIR ECOLOGICAL FUNCTIONS
    WANG Yong-Feng, LI Qing-Jun
    Chin J Plan Ecolo. 2005, 29 (3):  487-496.  doi:10.17521/cjpe.2005.0065
    Abstract ( 2613 )   PDF (827KB) ( 1207 )   Save
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    The classification, biological functions and the ecological roles in the atmospheric chemical processes of biogenic volatile organic compounds (BVOCs) emitted from plants of terrestrial ecosystems are summarized in this paper. BVOCs are grouped according to their structure and atmospheric lifetime into four categories: isoprenes, monoterpenes, other reactive BVOCs and other less reactive BVOCs. BVOCs are emitted from a diverse array of plants, and these emissions are affected by environmental factors and the chemical traits and synthesis mechanisms of different BVOCs. From a plant energetic standpoint, BVOC emissions may substantially reduce the amount of carbon that is fixed by vegetation and consequently may strongly affect plant productivity. Why plants give off such a relevant amount of resources is still a matter of debate. The most accepted opinion is the Thermotolerance Hypothesis, which states that isoprenes protect photosynthesis from damage caused by high leaf temperatures. Thylakoid membranes become leaky at moderately high temperatures, and isoprene could reside in thylakoid membranes for a time and enhance hydrophobic interactions. The second common hypothesis is that BVOCs serve as an antioxidant in leaves due to the rapid reaction of isoprenes with ozone and hydroxyl radicals. BVOCs play an important role in some ecological processes, such as deterring herbivores and attracting pollinators. More recently, isoprenes emitted by plants are thought to be associated with the enhancement of nitrogen assimilation from the atmosphere. This idea is based on the fact that early successional forest communities emit large amounts of isoprenes as a means for converting nitric oxide (NO) emitted by soils to available forms of nitrogen, such as nitrogen dioxide (NO2), nitric acid (HNO3), and various organic nitrates in the canopy atmosphere, which are assimilated by plants. In spite of all these hypotheses, the biological function of BVOCs still is unclear due to the lack of direct evidence. BVOCs also play an important role in atmospheric chemical processes. In the presence of NOx, BVOCs react in the atmosphere to form tropospheric ozone, an important pollutant in the atmosphere. These reactions may also cause a decrease in the concentration of the hydroxyl radical (OH) which could lead to the accumulation of methane and other greenhouse gases. A further consequence of these reactions is the formation of secondary organic aerosol particles, which has an influence on the regional climate as well as on the atmospheric environment. Compared with other areas, research on BVOCs in China is in its beginning state, but some basic work has been conducted. The work includes the identification of BVOCs emitted from some important plants and factors influencing their emission, BVOC flux at different scales and in various ecosystems, and ozone concentrations in some areas, which are thought to be related to BVOC emissions. In the future, research on BVOCs should focus on the following aspects: 1) BVOC surveys from different plant groups and their chemical and physical properties in the atmosphere; 2) The biosynthesis and metabolic mechanisms of BVOCs in plants; 3) The roles of BVOCs in plant-environment interactions; 4) Enhancement of the study of BVOCs in some unstudied regions, such as tropical Asia; and 5) Modeling of BVOCs.

    HEAVY METAL TOLERANCE AND HYPERACCUMULATION OF HIGHER PLANTS AND THEIR MOLECULAR MECHANISMS: A REVIEW
    SUN Rui-Lian, ZHOU Qi-Xing
    Chin J Plan Ecolo. 2005, 29 (3):  497-504.  doi:10.17521/cjpe.2005.0066
    Abstract ( 2654 )   PDF (665KB) ( 1141 )   Save
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    Owing to serious heavy metal pollution, much attention has been paid to its effects on soil-plant systems. The research of heavy metal tolerance and hyperaccumulation of higher plants has become a hot topic in the field of pollution ecology. With the development of molecular ecology, research on the mechanisms of heavy metal tolerance, detoxification and accumulation in higher plants has made progress in recent years. There are significant differences in the tolerance to and accumulation of heavy metals among higher plant species and genotypes. Root systems are the first entrance of heavy metal pollutants from the soil into plant. Root exudates reduce the availability and toxicity of metal pollutants and play an important role in ability for plants to absorb heavy metals. Almost all heavy metal ions enter root cells with the help of a metal transporter protein that are subsequently transported to the vacuole. The synthesis of PC in response to the stress caused by heavy metals is one of the adaptive responses common in higher plants. Heavy metal tolerant genotypes have higher levels of PC than non-tolerant genotypes under heavy metal stress. GSH is the substrate that synthesizes PC, which chelates the heavy metals. Heavy metal-PC chelatins are subsequently transported from the cytosol to the vacuole and heavy metal detoxification is thus achieved. MTs play the same role and in the same way as PC under heavy metal stress. The article reviews recent advances in understanding the role of root exudates, metal transporter proteins (MTs, PC and GSH), molecular mechanisms of heavy metal tolerance and hyperaccumulation in higher plants at the molecular level. Existing problems and major topics of future research were discussed.

    EFFECTS OF UV-B RADIATION ON PROTEIN AND NUCLEIC ACID SYNTHESIS IN THREE SPECIES OF MARINE RED-TIDE MICROALGAE
    ZHANG Pei-Yu, TANG Xue-Xi, CAI Heng-Jiang, YU Juan, YANG Zhen
    Chin J Plan Ecolo. 2005, 29 (3):  505-509.  doi:10.17521/cjpe.2005.0067
    Abstract ( 2194 )   PDF (512KB) ( 820 )   Save
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    Because destruction of the ozone layer is becoming increasingly more serious, the amount of ultraviolet radiation reaching the earth's surface, esp. UV-B radiation that is harmful to the DNA of organisms, has increased. The increase in UV-B radiation has altered ecological systems on the earth and has emerged as one of the most noticeable forces of global change. Interest on the potential dangers and injuries from enhanced UV radiation on marine organisms (esp. marine plankton) has increased. A lot of work has been done on UV-B radiation effects on marine microalgae at the molecular, cellular, physiological and biochemical levels; however, there are few reports on red-tide microalgae. In this study, the effects of UV-B radiation on the protein and nucleic acid synthesis of three red-tide microalgae species, Heterosigma akashiwo, Alexandrium tamarense and Skeletonema costatum, were investigated to better understand the influence of UV-B radiation on marine ecological systems and the mechanism and occurrence of red tides. The microalgae were cultured in Erlenmeyer flasks with f/2 medium. Salinity of the seawater was (30.0±1.0)‰ and the initial pH of the culture was (8.0±0.1). Cultures were grown at (19±1) ℃ under a 12 h∶12 h dark-light cycle at an illumination intensity of 3 000 Lx. Ultraviolet B radiation was provided by two UV-B tubes (Philips TL 40 w/12 uv) covered by a film of cellulose acetate (0.12 mm) to remove all radiation below 280 nm. In order to minimize the change of the filter properties of the film, the cellulose acetate was pre-burned for 48 h at a distance of 1 m from two UV-B lamps. Algae were exposed to UV-B radiation treatments of 0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8, 2.1, 2.4, 2.7, and 3.0 J·m-2, respectively, for 4 days. All experiments were carried out in triplicate. The responses of protein and nucleic acid synthesis in H. akashiwo, A. tamarense and S. costatum to UV-B radiation were studied using isotope-tracing methods. The results showed that the order of sensitivity from high to low in three red-tide microalgae to UV-B radiation was H. akashiwo, A. tamarense and S. costatum. The growth and DNA synthesis of H. akashiwo were inhibited. Whereas lower doses of UV-B radiation stimulated the growth and DNA synthesis of A. tamarense and S. costatum, higher doses had an inhibitory effect. The RNA and protein synthesis in all three species decreased with increased levels of UV-B radiation, but decreases in H. akashiwo were greater than in A. tamarense and S. costatum. Therefore, the sensitivity of RNA and protein synthesis to UV-B radiation enhancement in H. akashiwo was higher than that in A. tamarense and S. costatum.

    EFFECTS OF PLC/PLD INHIBITOR ON EXPRESSION AND REGULATION OF A NOVEL 69.5 kD HEAT-STABLE PROTEIN IN MAIZE SEEDLING ROOTS UNDER SALT STRESS
    WU Xue-You, SUN Li-Ping, LIU Li-Xia, WU Tao, LI De-Quan
    Chin J Plan Ecolo. 2005, 29 (3):  510-515.  doi:10.17521/cjpe.2005.0068
    Abstract ( 2036 )   PDF (348KB) ( 966 )   Save
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    Stress proteins play important roles in plant stress resistance. Phospholipase C/D (PLC/PLD) commonly exists in plants as a kind of signal transfer substance that can induce the expression of some stress proteins. The purpose of our study was to investigate the difference of protein expression between stress treatments and non-stress treatments. Furthermore, the function of PLC/PLD was studied in order to have a deeper insight into the mechanism of PLC/PLD in expression and regulation of stress proteins. Our results showed that a novel heat-stable protein with 69.5 kD-MW in stressed maize (Zea mays) (`LuDan-9002') seedling roots was induced in the 270 mmol·L-1 NaCl treatment and was separated by SDS-PAGE (Sodium dodecyl sulfate-Polyacrylamide gel electrophoresis). The expression content of this protein increased gradually with prolonged treatment of NaCl and still was maintained after the stress treatment was removed. The above results indicate that the 69.5 kD protein may be a kind of stress-adaptable protein. At the same time, a 20 μmol·L-1 ABA treatment could also induce the expression of the 69.5 kD protein, but its expression content was distinctly less than that treated with 270 mmol·L-1 NaCl. In plants treated with NaCl+ABA, the expression content of the 69.5kD protein was less than that treated with NaCl but more than that treated with ABA alone. Neomycin Sulfate (NS)+n-Butyl Alcohol (BA) treatment markedly diminished the expression of the 69.5 kD protein induced by NaCl, ABA or NaCl+ABA, and the inhibition of the two latter treatments strengthened with increasing concentrations of PLC/PLD inhibitors or increased time of treatment, whereas the inhibition of NaCl treatment was more complicated. The results suggest that different treatments have different sensitivities on inducing the expression of the 69.5 kD protein, and the function of PLC/PLD in signal transduction induced by different treatments is somewhat different.

    FURTHER DISCUSSION ON THE SHANDONG AND LIAODONG PENISULA FLORAS
    LU Fa-Jun, DU Xiao-Yan, QU Chang-You, YANG Mei-Juan, LI Fa-Zeng
    Chin J Plan Ecolo. 2005, 29 (3):  516-518.  doi:10.17521/cjpe.2005.0069
    Abstract ( 2159 )   PDF (259KB) ( 756 )   Save
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    This paper compares the flora of the Shandong peninsula with the neighboring floras on the south-central low hills of Shandong, the Liaodong peninsula and the northern Taihang and Heng mountains as a means to determine the appropriate classification for the Shandong and Liaodong peninsula floras. Shandong peninsula flora and the low hills flora of south-central Shandong have high homologies and a close relationship determined by similarity coefficients of genera. An UPGMA analysis illustrated a strong clustering of spermatophyta genera among Shandong peninsula, Liaodong peninsula and the north Taihang-Heng mountain floras. Our results do not support the view of Wu Zhengyi and Wang Hesheng who suggested that the Shandong peninsula flora and Liaodong peninsula flora should be divided into different subregions. The authors suggested that the Liaodong peninsula flora should be divided into the North China mountain flora and the Shandong-Liaodong hill be renamed as the Shandong hill subregion flora. Previous China vegetation classifications were based on the view that the Liaodong peninsula flora belonged to the warm temperate northern deciduous Quercus subzone and Shandong peninsula flora belonged to the warm temperate southern deciduous Quercus subzone.

    MEETING REPORT: THE BEIJING INTERNATIONAL SYMPOSIUM ONBIOLOGICAL INVASIONS, 6-11 JUNE 2004
    ALPERT Peter, MIAO Shi-Li, DONG Ming, HAN Xin-Guo
    Chin J Plan Ecolo. 2005, 29 (3):  520-522. 
    Abstract ( 1576 )   PDF (140KB) ( 715 )   Save
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