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Table of Content
    Volume 32 Issue 4
    30 July 2008
      
    Research Articles
    EVOLUTIONARY ECOLOGY: AN INTEGRATION OF ECOLOGY AND EVOLUTION
    ZHANG Da-Yong
    Chin J Plan Ecolo. 2008, 32 (4):  741-742.  doi:10.3773/j.issn.1005-264x.2008.04.001
    Abstract ( 2544 )   PDF (139KB) ( 1773 )   Save
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    PRELIMINARY STUDIES ON THE FLORAL BIOLOGY, BREEDING SYSTEM AND REPRODUCTIVE SUCCESS OF SINOJACKIA HUANGMEIENSIS, AN ENDANGERED PLANT IN A FRAGMENTED HABITAT IN HUBEI PROVINCE, CHINA
    ZHANG Jin-Ju, YE Qi-Gang, YAO Xiao-Hong, ZHANG Sheng-Ju, HUANG Hong-Wen
    Chin J Plan Ecolo. 2008, 32 (4):  743-750.  doi:10.3773/j.issn.1005-264x.2008.04.002
    Abstract ( 2825 )   PDF (338KB) ( 1487 )   Save
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    Aims Our objective was to assess the floral biology, breeding system and reproductive success in the naturally
    isolated population of Sinojackia huangmeiensis, an endangered plant in a fragmented habitat, in order to develop successful
    conservation strategies for this species.
    Methods We conducted field observations and artificial pollination experiments on the floral biology, pollination process
    and breeding system of S. huangmeiensis in southern Hubei Province.
    Important findings The flowers of S. huangmeiensis were bisexual and protandrous, with two to six in a raceme on the top of
    lateral branches. The life span of a single flower was approximately 5-7 days. The viable pollen persistence of a single
    flower was prolonged because of asynchronous dehiscing of anthers. The styles were always longer than the anthers in the
    opening flowers. Self-pollination was partially avoided by temporal and spatial isolation of male and female organs within
    the same flower. However, autogamous and geitonogamous selfing is unavoidable because of the large number of flowers on a
    single tree and the action of pollinators or wind on pollen dispersal. Our experiments indicated that no apomixis occurred,
    the breeding system was outcrossing with partial self-compatibility and pollinators were needed. The most frequent floral
    visitors were flies (Epistrophe balteata) and bees (Apis cerana and Habropoda sinensis). Fruit set and seed set in natural
    condition were 10.33% and 0.387, respectively. Lack of pollination insects, low pollination efficiency, deposition of self
    pollen and partial self-compatibility may account for the low fruit set and seed set. However, the large number of flowers in
    a single plant ensured production of fruits and seeds, which contributed to the natural population regeneration. From the
    evolutionary perspective, the partial self-compatibility may provide reproductive assurance and evolutionary potential, which
    was important to adapt to the fragmented habitat. We recommend recovery of the natural ecological system of pollinators to
    conserve the remnant population of S. huangmeiensis.
    GENETIC AND CLONAL DIVERSITY OF GLOBBA RACEMOSA, A HERB WITH A MIXED REPRODUCTIVE MODE
    ZHOU Hui-Ping, CHEN Jin, ZHANG Shou-Zhou
    Chin J Plan Ecolo. 2008, 32 (4):  751-759.  doi:10.3773/j.issn.1005-264x.2008.04.003
    Abstract ( 2872 )   PDF (297KB) ( 1136 )   Save
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    Aims Our objective was to understand the relative effects of reproductive mode, geographic distance and other
    potential factors on within- and among-population genetic and clonal diversity in Globba racemosa, a species that can
    reproduce sexually (via seeds) and asexually (via bulbils).
    Methods We investigated reproduction variation in the seven natural G. racemosa populations in Yuannan Province, China by
    measuring the number of sexually produced fruits and asexually produced bulbils. Genetic data were collected using inter-
    simple sequence repeat (ISSR) markers. We evaluated the distribution of genetic variance and levels of population genetic
    diversity and assessed the relationship between genetic diversity and reproduction variation.
    Important findings Globba racemosa has a relatively high genetic diversity at the species level (PPB=71.19%), and most
    genetic variances resided among populations (GST = 0.590 7). A high clonal diversity was found in this species (G/N = 0.88).
    No significant difference was detected between reproductive mode and genetic diversity or clonal diversity, which suggested
    that the mode of reproduction was not necessarily a determinant of population genetic diversity. There was a significant
    correlation between genetic and geographical distances (r = 0.68, p < 0.05), which indicated that genetic differentiation
    between populations was likely attributed to the effect of isolation by distance. Other factors (e.g., small sexual
    recruitment, somatic mutation and founder effect, etc.) could also play important roles in maintaining genetic and clonal
    diversity in G. racemosa.
    FLOWERING PHENOLOGY AND REPRODUCTIVE FEATURES OF THE RARE PLANT EREMOSPARTON SONGORICUM IN DESERT ZONE, XINJIANG, CHINA
    MA Wen-Bao, SHI Xiang, ZHANG Dao-Yuan, YIN Lin-Ke
    Chin J Plan Ecolo. 2008, 32 (4):  760-767.  doi:10.3773/j.issn.1005-264x.2008.04.004
    Abstract ( 2629 )   PDF (436KB) ( 1575 )   Save
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    Aims Flowering phenology is considered as an important fitness factor because it plays a crucial role in reproductive success. Our aim is to investigate the flowering phenology of Eremosparton songoricum, the 3rd Class national protected dwarf shrub with a fragmented distribution in Gurrbantuggut Desert of Xinjiang, China, to better understand its reproductive features.
    Methods We marked and observed 30 E. songoricum individuals with similar heights and crown diameters in the wild population of Cainan Oil Station in Gurrbantuggut Desert from 2005 to 2006. We observed the flowering course of each individual and inflorescence including the first flowering date, duration, mean flowering amplitude (flowers plant–1·d–1) and last flowering date and then calculated relative flowering intensity and synchrony indices. We also analyzed relationships between first flowering date, median date, duration, last flowering date, flowering amplitude and flowering synchrony, the correlation matrix between first flowering date and duration, flower number and fruit set.
    Important findings The flowering span of the population, individual, inflorescence and single flowering was approximately 26-29, 8-10, 5-7 and 2-3 d, respectively. None of the phenology index levels between 2005 and 2006 were distinctive. The synchrony index was 0.829. The relative flowering intensity showed one major peak from 10% to 30% and the skewness was 1.24. According to flower morphology and dehiscence, the typical single flowering process for a flower can be divided into four periods: pre-dehiscence, initial dehiscence, full dehiscence and withering. The correlation analysis among the first flowering date, duration, flower number and fruit number shows that 1) there is negative correlation between first flowering date and duration and a positive correlation to flower number and fruit number, 2) duration has a significant positive correlation to flower number and fruit number and 3) there is significant positive correlation between flower number and fruit number. Individuals with more flowers show a longer duration and more fruit than these with fewer flowers. As a rare plant in China’s desert zone, E. songoricum exhibits a so-called “mass-flowering” pattern, which may be regarded as an adaptive strategy to ensure its reproductive success.
    COEVOLUTION BETWEEN TWO INTERNAL OVIPOSITING FIG WASPS AND HOST FICUS CURTIPES
    ZHANG Feng-Ping, PENG Yan-Qiong, YANG Da-Rong
    Chin J Plan Ecolo. 2008, 32 (4):  768-775.  doi:10.3773/j.issn.1005-264x.2008.04.005
    Abstract ( 2935 )   PDF (297KB) ( 1112 )   Save
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    Aims Fig trees (Ficus) and their pollinating wasps (Chalcidoidea, Agaonidae) form a highly obligated mutualism. In
    addition, Ficus species also host some non-pollinating fig wasps, most of which oviposit from the outside of figs, and only a
    few have evolved fig-entry behavior. Ficus curtipes hosts an internal ovipositing non-ollinating fig wasp, Diaziella yangi,
    in Xishuangbanna, and it is similar to the pollinating fig wasp (Eupristina sp.). Our objective was to investigate whether
    there was coevolution between D. yangi and host F. curtipes in aspects of morphology, behavior and ecology.
    Methods Head length and width of the fig wasps, along with length of the ovipositors and styles, were measured using
    dissecting microscopy. In the field, the behavior of wasp’s entry in female floral phase was observed, and the mating and
    emerging behavior in male floral phase were observed in the laboratory. Moreover, we recorded a number of foundress in the
    fig female floral phase, and counted the number of wasps and seeds in the male floral phase.
    Important findings The head shape (length:width) of female D. yangi was strongly correlated with that of the female
    pollinator Eupristina sp., while there was no corresponding correlation in male head shape. The style-length of figs was in
    the reach of Eupristina sp. and D. yangi. The emergence time for each Eupristina sp. from a gall was usually for 3–5 h, and
    the mating time lasted 17–19 min. The emergence time for each D. yangi was usually for 18–20 min, and the mating time
    lasted 20–30 s. In nature, almost 90% of figs at female floral phase averaged only one D. yangi and one Eupristina sp. In
    the natural community, D. yangi has a significant negative effect on the pollinator, but a positive effect on the number of
    viable seeds. Both internal ovipositing species entered fig in the same day of female floral phase and left the fig at the
    same time (figs’ male floral phase). Results suggested that D. yangi can pollinate the figs, similar to the pollinator
    Eupristina sp. It has high degree of co-adaptation with the host F. curtipes. This is possibly an example of evolving from
    parasitism to mutualism.
    CORRELATION BETWEEN FLORAL TRAITS OF CHRYSANTHEMUM (DENDRANTHEMA MORIFOLIUM) AND INSECT VISITORS
    WANG Wei, DAI Hua-Guo, CHEN Fa-Di, GUO Wei-Ming
    Chin J Plan Ecolo. 2008, 32 (4):  776-785.  doi:10.3773/j.issn.1005-264x.2008.04.006
    Abstract ( 2720 )   PDF (1013KB) ( 1409 )   Save
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    Aims Chrysanthemum (Dendranthema morifolium) is a self-incompatible allogamous plant. Its main pollination vectors are bees and butterflies. Our aim is to investigate and evaluate the effects of flower color, corolla density, corolla diameter, tubular flower diameter, plant height and essential oil components on attracting insect visitors.
    Methods We investigated the floral traits of 19 chrysanthemum cultivars. Five cultivars with different floral traits were selected for identification of essential oil components using a Thermo Finnigan TRACE GC/DSQ spectrometer, and data on essential oil components were analyzed by SPSS (Analysis of Variance, stepwise and correlation).
    Important findings Bees (Apis mellifera) preferred yellow color flower to others including orange yellow, red, mauve, orange and pink. The number of visiting bees was significantly correlated with corolla density (r=0.715, p<0.01), indicating that the effect of a colony was more significant than the size of a single flower head. For all tested traits of a single flower head, tubular flower diameter had the most significant influence on attracting bees (r=0.622, p<0.01), followed by corolla diameter (r = –0.502, p<0.05). Butterflies (Vanessa indica) preferred red color flowers, and tubular flower diameter significantly influenced the number of pollinating butterflies (r=0.635, p<0.01). Results suggested that rewards from the flowers were the dominating attractive factors to visitors. The effect of single flower head on number of visiting butterflies was more significant than corolla density (r=0.487, p<0.05). In all tested traits of a single flower head, flower color and tubular flower diameter were the main influencing factors on numbers of visiting butterflies. The main essential oil components, such as camphor (rbees= –0.191, p>0.05; rbutterflies=0.507, p>0.05) and borneol (rbees=0.354, p>0.05; rbutterflies= –0.387, p>0.05) had little correlation with number of visiting insects, whereas some specific essential oil components, such as camphene (r= –0.909, p<0.05), 2-pentadecanone,6,10,14-trimethyl- (r=0.882, p<0.05) showed significant correlations with number of visiting bees, and α-terpineol (r=0.979, p<0.01), cis-limonene oxide (r=0.979, p<0.01), E-farnesene epoxide (r=0.979, p<0.01), p-mentha-6,8-dien-2-ol, cis- (r=0.973, p<0.01), p-menth-1-en-8-ol (r=0.962, p<0.01) and p-menth-1-en-4-ol, [R]-[–]-(r=0.957, p<0.05) showed significant correlations with number of visiting butterflies. Therefore, some specific essential oil components were important in attracting visitors.
    DYNAMICS SIMULATION OF NET PRIMARY PRODUCTIVITY BY A SATELLITE DATA-DRIVEN CASA MODEL IN INNER MONGOLIAN TYPICAL STEPPE, CHINA
    ZHANG Feng, ZHOU Guang-Sheng, WANG Yu-Hui
    Chin J Plan Ecolo. 2008, 32 (4):  786-797.  doi:10.3773/j.issn.1005-264x.2008.04.007
    Abstract ( 3121 )   PDF (429KB) ( 2087 )   Save
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    Aims Vegetation net primary productivity (NPP) and its responses to global change have been focuses of global change research. Accurately estimating the spatial patterns and temporal dynamics of net primary productivity (NPP) of terrestrial ecosystems is of great interest to human society and is necessary for understanding the carbon cycle of the terrestrial biosphere. But only a few evidences in various biomes are available on the performance of global models of terrestrial net primary productivity (NPP) at ecosystem level.
    Methods Vegetation net primary productivity (NPP) derived from a carbon model (Carnegie-Ames- Stanford Approach, CASA) and its inter-annual change at ecosystem level in Inner Mongolian typical steppe, China, are investigated in this study using 1982~2002 time series data sets of normalized difference vegetation index (NDVI) at 8 km spatial resolution and paired ground-based information on vegetation, climate, soil, and solar radiation, after CASA model is validated by the aboveground biomass of 13 years’ continuous observation.
    Important Findings Results show that 21-year averaged annual NPP is 290.23 g C·m–2·a–1, ranging between 145.80 g C·m–2·a–1 and 502.84 g C·m–2·a–1. From 1982 to 2002, annual NPP shows a slightly increasing trend, while from 1982 to 1999 a significant increase (p<0.01) is observed, and the increased NPP is mainly due to the increases of the amplitude of the NPP annual cycle. Annual precipitation significantly affects the variation of NPP, and there is no significant positive correlation between NPP and annual mean temperature.
    SPATIAL-TEMPORAL VARIATIONS IN NET PRIMARY PRODUCTIVITY ALONG NORTHEAST CHINA TRANSECT (NECT) FROM 1982 TO 1999
    ZHANG Feng, ZHOU Guang-Sheng
    Chin J Plan Ecolo. 2008, 32 (4):  798-809.  doi:10.3773/j.issn.1005-264x.2008.04.008
    Abstract ( 2622 )   PDF (730KB) ( 1712 )   Save
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    Aims Net primary productivity (NPP) and its responses to global climate change have been important issues of
    global change research. Accurately estimating spatial patterns and temporal dynamics of NPP of terrestrial ecosystems is
    important to human society and is necessary for understanding the carbon cycle of the terrestrial biosphere. The Northeast
    China Transect (NECT), one of the International Geosphere-Biosphere Programme terrestrial transects, is an ideal region for
    identifying effects of climate change on spatial-temporal variations in NPP.
    Methods We investigated NPP derived from a carbon model (Carnegie-Ames-Stanford Approach, CASA) and its spatial-temporal
    variations along NECT 1982–1999 time series data sets of normalized difference vegetation index (NDVI) at 8 km spatial
    resolution and paired ground-based information on vegetation, climate, soil and solar radiation, after validating the CASA
    model using NPP data from 33 stations along NECT.
    Important findings The 18-year averaged annual NPP along NECT was 426 g C·m–2·a–1, ranging from 58 to 811 g C·m–2·a–1
    and decreased from east to west, which is consistent with the distribution of precipitation. Total annual NPP changed from
    0.218 to 0.325 Pg C over the 18 years, with an average of 0.270 Pg C. Two distinct periods (1982–1990 and 1991–1999) of NPP
    variations were observed, separated by a sharp reduction during 1990–1991. From 1982 to 1990, a significant increase of
    0.007 5 Pg C·a–1 was observed; from 1991 to 1999, annual NPP showed no marked trend. From 1982 to 1999, annual NPP showed a
    significant increase, accounting for 56.65% of the whole transect, and the largest annual NPP increase during 1982–1999
    appeared in cultivated land, typical steppe and meadow steppe, accounting for 62.6% of the increment of the whole region,
    while desert steppe and typical steppe showed higher sensitivity to climate change. Spatial distribution of NPP along NECT is
    determined by the pattern annual precipitation, and temporal variation of NPP is influenced by changes in annual
    precipitation and annual total solar radiation.
    SENSITIVITY ANALYSIS ON METHODS OF ESTIMATING CARBON SEQUESTRATION IN GRASSLAND ECOSYSTEM OF INNER MONGOLIA, CHINA
    CHANG Rui-Ying, TANG Hai-Ping
    Chin J Plan Ecolo. 2008, 32 (4):  810-814.  doi:10.3773/j.issn.1005-264x.2008.04.009
    Abstract ( 2712 )   PDF (293KB) ( 1085 )   Save
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    Aims Improved rangeland management activities, such as prohibiting grazing, contribute significantly to increased carbon storage in grassland at low cost. Estimating carbon sequestration is important to evaluating cost and potential of carbon sequestration in grassland. We described and compared two methods for estimating carbon sequestration, stock-difference and gain-loss, in order to assess their suitability and accuracy for estimating cost of carbon sequestration in grassland.
    Methods Using the grassland in Xilin River Basin of Inner Mongolia as a case study, we estimated the amount and cost of carbon sequestration by the stock-difference and gain-loss methods and compared results through sensitivity analysis.
    Important findings There are significant differences in the amount and cost of carbon sequestration between the two methods, because of different grazing intensities. The cost of carbon sequestration is a function of grazing intensity and size of study area, with a linear relationship between cost and grazing intensity and a nonlinear relationship between cost and size of study area. The gain-loss method is more sensitive to grazing intensity and size of study area. The stock-difference method is more accurate and suitable for estimating cost of grassland carbon sequestration. However, the main reason for the difference between the two methods is different conditions of study areas. The two methods are essentially the same with regard to grassland succession. With sufficient data, both methods to estimate the amount and cost of carbon sequestration in grassland will give similar results.
    STRUCTURE AND SPECIES COMPOSITION OF GROUND BRYOPHYTE COMMUNITY OF HIGH-ALTITUDE YOUNG SILVICULTURAL CUTOVERS IN RANGTANG COUNTY, CHINA: EVALUATION ON EFFECTS OF CLEAR- CUTTING AND SILVICULTURAL MANAGEMENT
    YAN Xiao-Li, BAO Wei-Kai
    Chin J Plan Ecolo. 2008, 32 (4):  815-824.  doi:10.3773/j.issn.1005-264x.2008.04.010
    Abstract ( 2756 )   PDF (381KB) ( 1072 )   Save
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    Aims Traditional forestry management influences biodiversity. Revealing effects of clear-cutting and silvicultural
    history on ground bryophyte communities is important for evaluating impacts of forest management on biodiversity.
    Methods We selected four sites with similar physical conditions but different development phases in Rangtang County. We
    investigated bryophyte and vascular plant vegetation, including species composition and structural characteristics, in 30
    plots in each site. ANOVA analysis was used to detect differences among bryophyte communities, and the relationship between
    vascular plant and bryophyte communities was examined by partial correlations.
    Important findings Bryophyte composition changed significantly during developmental processes of young forests. Photophilic
    or pleurocarpous mosses were dominant species, while some hygrophilous mosses expanded their populations and become dominant
    species locally and drought-tolerant species occurred because of disturbance. Richness index (22–37) and diversity index
    (0.37–1.08) increased during the process of development, and the four young forestlands had differences in structural
    characteristics. There was a positive relationship between cover of tree and shrub layers and development of bryophytes.
    Shrub layer significantly promoted bryophyte richness, while pioneer grass with strong development and litter restrained
    bryophyte development. Characteristics of development in tree, shrub, litter layer and their interaction changed dynamically
    during the developmental process. Promoting development of tree and shrub layers has an important role on enhancing
    bryophytes.
    QUANTITATIVE CHARACTERISTICS AND SPATIAL DISTRIBUTION PATTERNS OF EUPTELEA PLEIOSPERMUM POPULATIONS IN RIPARIAN ZONES OF THE SHENNONGJIA AREA, CENTRAL CHINA
    WEI Xin-Zeng, HUANG Han-Dong, JIANG Ming-Xi, YANG Jing-Yuan
    Chin J Plan Ecolo. 2008, 32 (4):  825-837.  doi:10.3773/j.issn.1005-264x.2008.04.011
    Abstract ( 3013 )   PDF (478KB) ( 1504 )   Save
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    Aims Euptelea pleiospermum, an endangered tree species confined to East Asia, grows mainly in the riparian zones of the Yandu, Xiangxi, Nan and Du rivers in the Shennongjia area. We studied the quantitative characteristics, spatial distribution patterns and dynamics of E. pleiospermum populations. Our objectives were to explore the cause and mechanism that confines the species to riparian zones and to provide a theoretical basis for conservation.
    Methods We placed 30 quadrats (20 m × 30 m) in the riparian zones of the four rivers. We recorded the diameter at breast height (DBH) and height (H) of each tree and divided them into seven size classes: Ⅰ, H < 0.33 m; Ⅱ, H≥0.33 m and DBH < 2.5 cm; Ⅲ, 2.5 cm≤DBH < 7.5 cm, etc. Using the sides of the quadrat, we recorded the coordinates (x, y) of every E. pleiospermum individual. To analyze spatial distribution pattern dynamics, we divided trees into three stages: young (Ⅰand Ⅱ); middle-aged (Ⅲ and Ⅳ); and old trees (Ⅴ–Ⅶ).
    Important findings The spindle-shaped size class structure suggests that the populations of E. pleiospermum are declining, but E. pleiospermum can maintain its populations over long periods by sprouting. The mortality of size classes Ⅰ and Ⅱ is negative, indicating a shortage of size class Ⅰ and Ⅱ individuals. The two peaks of mortality at size classes Ⅳ and Ⅶ are caused by self-thinning and approaching the species’ longevity, respectively. The survivorship curves of E. pleiospermum populations generally match Deevey Type Ⅰ, indicating that the habitat of the riparian zone is suitable for E. pleiospermum. The spatial distribution pattern tends to be clumped, but changes from clumped to random as a result of human disturbance and influence of the natural environment and graduallychanges from clumped to random with growth from young to middle-aged to old trees.

    WATER TABLE AND THE DESERT RIPARIAN FOREST COMMUNITY IN THE LOWER REACHES OF TARIM RIVER, CHINA
    HAO Xing-Ming, LI Wei-Hong, CHEN Ya-Ning
    Chin J Plan Ecolo. 2008, 32 (4):  838-847.  doi:10.3773/j.issn.1005-264x.2008.04.012
    Abstract ( 2569 )   PDF (690KB) ( 1013 )   Save
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    Aims Intensive utilization of water resources in the Tarim River watershed during the past five decades has
    reduced flows in a 320 km section in the lower reaches, drying lakes and lowering groundwater levels. This has degraded
    Populus euphratica forests over large areas, reducing biodiversity and impairing ecosystem structure and function. Our
    objectives are to study ecological responses of the natural vegetation to changes in the water table and determine the water
    table depth needed for the survival of desert riparian forest.
    Methods We divided water table depths into a gradient of six levels based on annual mean groundwater level and sampled
    vegetation plots for each of the six levels. We analyzed niche characteristics and species diversity of the primary
    populations for the six water table levels.
    Important findings With an increase of groundwater depth, the niche breadth of plant populations increases approximately
    monotonically, reaching a maximum at a groundwater depth of 4–6 m, after which the niche breadth decreases. Niche overlap is
    the smallest and plant species abundance highest at groundwater depth of 4–6 m. The Hill species diversity index showed
    highest species diversity with groundwater depth of 2–4 m, followed by 4–6 m and then 0–2 m. At groundwater depth > 6 m,
    diversity is low and the diversity curve becomes smooth. Therefore, to restore the degraded vegetation in the lower reaches
    of Tarim River, the groundwater depth should be at least 6 m, with 4–6 m in most areas and 2–4 m in some areas near the
    water course.
    CORRELATIONS BETWEEN METEOROLOGICAL FACTORS AND LEAF ELEMENT CONTENTS IN DESERT PLANT REAUMURIA SOONGORICA
    MA Jian-Ying, FANG Xiang-Wen, XIA Dun-Sheng, DUAN Zheng-Hu, CHEN Fa-Hu, WANG Gang
    Chin J Plan Ecolo. 2008, 32 (4):  848-857.  doi:10.3773/j.issn.1005-264x.2008.04.013
    Abstract ( 2675 )   PDF (531KB) ( 1404 )   Save
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    Aims Reaumuria soongorica is a major dominant of desert shrub vegetation in arid regions of China. Our objectives
    were to investigate correlations between foliar characteristics of this desert plant and meteorological factors and to
    identify the major factor influencing variations in dif-ferent environments.
    Methods We collected 407 individuals of R. soongorica from 21 natural populations in its major area of distribution in
    northwestern China and measured the nitrogen, phosphorus, potassium and leaf water content and stable carbon isotope
    composition in leaves. Meteorological data, including mean annual precipitation and temperature, evaporation, mean relative
    humidity and duration of sunshine, were collected from the Cold and Arid Environmental and Engineering Research Institute,
    Chinese Academy of Sciences. The relationships between foliar characteristics and meteorological factors were analyzed by
    simple linear regression and Pearson’s correlation.
    Important findings Variation of leaf nitrogen content in R. soongorica was due to the complex effect of meteorological
    factors. Mean relative humidity was the limiting factor that affected leaf potassium content and stable carbon isotope
    composition. Evaporation and duration of sunshine were the key factors influencing leaf phosphorus content and water content,
    respectively. The impacts of climate conditions on foliar characteristics of R. soongorica were notable, and the
    contributions of different meteorological factors to foliar characteristics differed significantly. This pattern of variation
    in foliar characteristics responded to different meteorological conditions, reflecting the environmental status and the
    stable extent of desert ecosystems dominated by R. soongorica.
    DYNAMICS OF NITROGEN CONTENT OF PHRAGMITES AUSTRALIS IN PANJIN WETLAND, CHINA
    JIA Qing-Yu, ZHOU Guang-Sheng, ZHOU Li, XIE Yan-Bin
    Chin J Plan Ecolo. 2008, 32 (4):  858-864.  doi:10.3773/j.issn.1005-264x.2008.04.014
    Abstract ( 2529 )   PDF (343KB) ( 1206 )   Save
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    Aims We analyzed nitrogen content of Phragmites australis in relation to leaf area index, biomass, etc., as well as seasonal dynamics in growth parameters and nitrogen content and their relationship to stability of P. australis in Panjin wetland, China.
    Methods We sampled plots to determine biomass (dry matter) and nitrogen content of different organs of P. australis during the growing season of 2005. Nitrogen content was measured by the methods of Bao (2000).
    Important findings The nitrogen contents in different organs of P. australis were remarkably different, with leaf > stem > fibre > rhizomes and with aboveground parts > belowground parts. Maximum values of all organs appeared in earlier stages of growth. Plant nitrogen content and leaf nitrogen content closely fit a negative linear relationship with accumulative leaf area index. Stem nitrogen content increased with increasing soil depth, and the fibre nitrogen content had a close negative linear relationship with its biomass. Total plant nitrogen storage by P. australis in Panjin wetland was crescent with its development during the growing season. Nitrogen reserves in aboveground and underground parts (0–30 cm soil depth) were 25.76 and 24.04 g·m–2, respectively.
    ECOPHYSIOLOGICAL RESPONSE OF EMMENOPTERYS HENRYI AT DIFFERENT ALTITUDES IN CHINA’S DAPAN MOUNTAIN NATURAL RESERVE
    KANG Hua-Jing, LIU Peng, XU Gen-Di, CHEN Zi-Lin, WEI Fu-Min
    Chin J Plan Ecolo. 2008, 32 (4):  865-872.  doi:10.3773/j.issn.1005-264x.2008.04.015
    Abstract ( 2606 )   PDF (446KB) ( 1050 )   Save
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    Aims Emmenopterys henryi, an endemic species in China, is one of the Chinese national second protective wild plants. We investigated the ecophysiological responses of E. henryi at different altitudes in Dapan Mountain, a National Natural Reserve in Eastern China, to determine ecophysiological adaptation mechanisms of the species antioxidative system.
    Methods We studied the content of Chla、Chlb and Chl(a+b), malondialdehyde (MDA), ascorbate (AsA) and praline (Pro), the membrane permeability (MP), specific leaf area (SLA), and the activities of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) in leaves of E. henryi from different altitudes (A1: 550-650 m, A2: 680-770 m, A3: 810-900 m and A4: 970-1 100 m) in Dapan Mountain.
    Important findings Chla, Chlb and Chl(a+b) reduced with increasing altitude. At A4, they decreased 21.32%, 31.53% and 24.96%, respectively, compared with that in A1. SLA decreased with increasing altitude. MP and content of MDA had a similar change: reaching minimum values in A3 and maximum in A4, indicating that E. henryi was least damaged in A3 and most in A4. Pro and AsA were at their maxima in A3, 139.33% and 10.60% respectively compared with A1. The activity of SOD, POD, CAT and APX were all the weakest in A1, however, they showed different changes. The activity of SOD progressively increased, while the activity of POD, CAT and APX initially increased and then decreased, with peak of activity of POD and APX in A3 and CAT in A2. More non-enzyme antioxidant and stronger activity of enzyme were favourable for eliminating intracellular active oxygen, keeping the cell membrane in a stable condition and ensuring normal growth of plants. In general, 810-900 m (middle altitude) is the best for the growth of E. henryi, while 970–1 100 m (high altitude) is the poorest. Therefore, altitude should be considered when biodiversity conservation of E. henryi is to be carried out, especially when transplanting E. henryi from degraded areas in the wild.
    COMPARATIVE STUDIES ON CRYSTAL IDIOBLASTS OF FIVE DESERT C4 PLANTS
    YAN Qiao-Di, SU Pei-Xi, CHEN Hong-Bin, ZHANG Ling-Mei
    Chin J Plan Ecolo. 2008, 32 (4):  873-882.  doi:10.3773/j.issn.1005-264x.2008.04.016
    Abstract ( 2780 )   PDF (2787KB) ( 1498 )   Save
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    Aims Tissue cells that are specialized to produce crystals are referred to as crystal idioblasts. Crystal
    composition is predominantly calcium oxalate. Calcium oxalate crystal formation in plants appears to play a central role in a
    variety of important functions. Our aims are to study the occurrence, structures and functions of crystal idioblasts in C4
    desert plants and assess the significance of crystal idioblasts in their drought resistance.
    Methods We selected five C4 desert plants whose photosynthetic organs are greatly deformed in appearance and structure. We
    investigated anatomical structures in desert plants Salsola collina and S. arbuscula and compared differences of assimilating
    shoots among Haloxylon ammodendron, H. persicum and Calligonum mongolicum using light microscopy. We identified crystals by
    using histochemical method and energy dispersive spectroscopy (EDS) and observed crystal microstructures under a scanning
    electron microscope.
    Important findings Crystal idioblasts exist in all five species, but there are differences in their distribution, position,
    amount, size and configuration. Haloxylon persicum and H. ammodendron have the most crystal idioblasts. Salsola arbuscula has
    fewer crystals existing between palisade tissues and epidermal cells. The fewest crystals exist in the water-storage tissue
    of S. collina. The crystals are in the water-storage tissue or near the palisade tissue in Calligonum mongolicum. The study
    of different parts of assimilating shoots among H. ammodendron, H. persicum and C. mongolicum shows that in H. ammodendron
    the base has the most crystals, fewer in middle, least in top; in H. persicum the top of assimilating shoots has the most
    crystals, fewer in middle and base; there are more mucilage cells in top and base of C. mongolicum and fewer in middle; the
    base has few palisade tissue cells but developed vascular tissues. Histochemical and EDS results indicated that crystal
    nature of H. ammodendron, H. persicum, C. mongolicum and S. arbuscula is calcium oxalate. Among the five plants, H. persicum
    and H. ammodendron have the most crystal idioblasts, but there are mucilage cells in assimilating shoots of C. mongolicum.
    SEED GERMINATION CHARACTERISTICS OF BETULA ALBO-SINENSIS AT MOUNTAIN TAIBAI, CHINA
    REN Jian-Yi, LIN Yue, YUE Ming
    Chin J Plan Ecolo. 2008, 32 (4):  883-890.  doi:10.3773/j.issn.1005-264x.2008.04.017
    Abstract ( 2619 )   PDF (414KB) ( 1147 )   Save
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    Aims Betula albo-sinensis occurs in the middle to high elevations of Taibai Mountain, China where its forests have
    regeneration barriers. We studied the germination and physiological characteristics of B. albo-sinensis seeds to investigate
    natural regeneration.
    Methods We observed 2 400 seeds of B. albo-sinensis without pericarp and recorded germination rates. We studied germination
    rates under different photosynthetically active radiation (PAR) and photoperiod (high light: PAR = 464.7 μmol photons·m-2·s-1, 12 h·d–1; middle light: PAR = 233.8 μmol photons·m-2·s-1, 12 h·d–1; low light: PAR = 233.8 μmol photons·m-2·s-1,
    0.5 h·d–1), different day/night temperatures (25/20 ℃, 20/15 ℃ and 15/10 ℃) and with and without pericarp. We also
    recorded germination rates without light, under different culture media (soil and sand) and mulch (broad leaf, needle leaf
    and mixed leaf) or covered with leaf (broad leaf and mixed leaf).
    Important findings We found that 54.29% of the seed is full in the fully maturated ones. The optimum germination temperature
    is 25/20 ℃, and few seeds germinated under 15/10 ℃. Germination rates under middle light were highest, and there was no
    seed germination under no light. Shelling the pericarp could improve germination rates. Germination rates declined in the
    groups covered with mulch, but there was no significant difference among culture media. We conclude that B. albo-sinensis
    seed germination depends on natural disturbances in its natural environment.
    CHANGES OF SOIL MICROBIAL PROPERTIES AFFECTED BY DIFFERENT LONG-TERM FERTILIZATION REGIMES
    LI Juan, ZHAO Bing-Qiang, LI Xiu-Ying, JIANG Rui-Bo, SO Hwat Bing
    Chin J Plan Ecolo. 2008, 32 (4):  891-899.  doi:10.3773/j.issn.1005-264x.2008.04.018
    Abstract ( 2740 )   PDF (355KB) ( 1607 )   Save
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    Aims Soil health is important for sustainable development of terrestrial ecosystems. We studied soil microbial properties such as microbial biomass, functional diversity of microbial communities and soil enzyme activities in order to illustrate the function of soil microbial properties as bio-indicators of soil health.
    Methods A 15-year fertilizer experiment on Fluvo-aquic soil in Changping County, Beijing, China, was established in a wheat-maize rotation in 1991 to explore long-term impact of four different fertilization regimes: no fertilizer (CK), mineral fertilizers (NPK), mineral fertilizers plus swine manure (NPKM) and mineral fertilizers with maize straw incorporated (NPKS). We used BIOLOG ECO micro-plate analysis to study the functional diversity of microbial communities.
    Important findings Long-term fertilization regimes had clear effects on soil microbial properties compared to CK. Soil microbial biomass C & N, urease activity, soil organic matter, soil total nitrogen, and soil total phosphorus increased more with NPKM and NPKS than with NPK and CK. The utilization ability of microbial communities for carbon and functional diversity of microbial communities increased to some extent with NPKM and NPKS, but had no significant differences with CK. NPKM and NPKS could significantly decrease soil pH and C/N. The utilization ability of microbial communities for carbon and the functional diversity of microbial communities under CK were much higher than those under NPK since the other soil microbial properties were higher under NPK treatment. Catalase activity had no obvious differences among the four treatments. Principal component analysis of carbon utilization for soil microbial communities indicated there were different carbon substrate utilization patterns among the fertilization treatments.
    COMPARATIVE STUDIES ON SEASONAL DYNAMICS OF SOIL ENZYMATIC ACTIVITIES AND SOIL NUTRIENT AVAILABILITY IN MONO- AND MIXED- CULTURE PLANT COMMUNITIES OF AGERATINA ADENOPHORA AND SETARIA SPHACLATA
    JIANG Zhi-Lin, LIU Wan-Xue, WAN Fang-Hao, LI Zheng-Yue
    Chin J Plan Ecolo. 2008, 32 (4):  900-907.  doi:10.3773/j.issn.1005-264x.2008.04.019
    Abstract ( 2620 )   PDF (423KB) ( 1455 )   Save
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    Aims Our objectives were to determine: 1) the effect of different plant communities on soil enzymatic activities
    and soil nutrient availability to the plants, 2) the correlation between soil enzymatic activities and soil nutrient
    availability to the plants, and 3) the potential competition for resources among target species and competitive strategy of
    each species.
    Methods We correlated four soil enzyme activities and availability of three major soil nutrients (N, P and K) in three plant
    communities: monoculture of Ageratina adenophora (A), monoculture of Setaria sphacelata (S), and mixed culture of A.
    adenophora and S. sphacelata (A+S).
    Important findings Concentrations of soil NH4+-N and NO3--N in community A were significantly lower than in S and A+S
    (p<0.01), but there was no significant difference between A and A+S (p>0.05). The available P and K in all communities
    decreased significantly in the order of A>S>A+S (p<0.01). Soil protease and urease activities in all communities decreased in
    the order of S>A+S>A and A+S>S>A (p<0.01), respectively. Soil phosphatase and invertase activities increased in the order of
    A+Sp<0.01), respectively. The soil NO3--N and available P and K in all communities decreased with
    increasing plant age. Soil NH4+-N contents showed a unimodal concentration curve peaking in September. Soil protease and
    urease activities increased in all communities with peak values in November. The activities of other soil enzymes peaked only
    once in July. Correlations between soil enzymatic activities and soil nutrient availability were consistent in all
    communities. S. sphacelata showed higher net ammonification and nitrification rates as compared to A. adenophora, but S.
    sphacelata showed higher reduction in available P and K. This may explain why S. sphacelata out-competed A. adenophora in
    community A+S. The differences in soil enzymatic activities of the different plant communities are due to a potential
    mechanism that resulted in variations in the nutrients availability.
    EFFECT OF RANGE FIRE ON NITROGEN FIXATION OF COLLEMA TENAX IN A SEMIARID GRASSLAND OF INNER MONGOLIA, CHINA
    WU Qing-Feng, LIU Hua-Jie
    Chin J Plan Ecolo. 2008, 32 (4):  908-913.  doi:10.3773/j.issn.1005-264x.2008.04.020
    Abstract ( 2676 )   PDF (265KB) ( 945 )   Save
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    Aims Collema tenax is a common N-fixing lichen in arid and semiarid grasslands, where range fire can be an
    important factor influencing ecosystem structure and function. The response of N-fixing activity of lichens to range fire has
    received little attention in ecological studies. Our purpose was to investigate the short-term effects of range fire on N
    fixation of C. tenax.
    Methods Three months after a controlled burn at the Inner Mongolian semiarid grassland, we measured plant cover, litter
    cover and N-fixing activity of C. tenax in both burned plots and control plots. N-fixing activity was measured using
    acetylene reduction assay. One-Way ANOVA was applied to compare N-fixing activity between treatments.
    Important findings At the individual scale, N-fixing activity of C. tenax decreased by 42.3% for individuals with a burned
    thallus, but increased by 28.4% for those with an intact one, as compared to that observed in unburned plots. These results
    show counteractive effects of burning on N fixation of C. tenax at individual scale, i.e., 1) negative effect through damage
    on lichen thallus and potential deterioration in surface water and temperature conditions and 2) positive effect as a result
    of increased light availability via removal of litter and plant biomass and, to a lesser extent, a fire-induced nutrient
    pulse on the soil surface. At the population scale, no significant effects of burning on N-fixing activity of this lichen
    were found, which may be attributable to the counteractive responses of N fixation of C. tenax at the individual scale.
    FFECTS OF MAIZE INTERCROPPING WITH DIFFERENT GENOTYPES ON LEAF SENESCENCE AND GRAIN YIELD AND QUALITY
    LIU Tian-Xue, LI Chao-Hai, MA Xin-Ming, ZHAO Xia, LIU Shi-Ying
    Chin J Plan Ecolo. 2008, 32 (4):  914-921.  doi:10.3773/j.issn.1005-264x.2008.04.021
    Abstract ( 2731 )   PDF (349KB) ( 1182 )   Save
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    Aims Although maize (Zea mays) intercropped with other species enhances utilization efficiency of natural
    resources such as light, heat, water and fertilizer, which increases yields, it has caused great difficulty in cultivation.
    Presently, there is substantial agronomic evidence for yield advantage among mixtures, maize intercropping with different
    genotypes included. Our objective was to investigate the effects of maize intercropping with different genotypes on the
    senescence of leaves, yield and quality.
    Methods We conducted a field experiment on the farm of Henan Agricultural University, Zhengzhou, China, using four maize
    varieties, three semi-compact plant types (YY19, ZD041 and LD981) and one compact plant type (ZD958). The experimental plots
    of 6 m×6 m were separated by 1 m. The experiments were planted by hand with rows oriented north-south and spacing of 0.70
    and 0.50 m. The ratio of two maize varieties intercropped was 1:1 per row. The planting density was 67 500 plants·hm–2
    .There were six treatments: each of the varieties alone, YY19 intercropped with ZD041 (YY19║ZD041), and ZD958 intercropped
    with LD981 (ZD958║LD981). There were four replicate plots for each treatment, arranged in a randomized complete block
    design.
    Important findings The activities of SOD and POD of leaves increased in the intercropping treatments 10 days after silking,
    which resulted in decreased MDA contents of leaves. The activities of CAT of leaves in ZD041 and ZD958 increased or increased
    markedly, while YY19 and LD981 decreased slightly. The changes of activities of SOD and POD and contents of MDA in leaves
    remained similar 40 days after silking. Meanwhile, the activities of CAT of leaves increased, among them YY19 increased
    significantly. Also, yields, land equivalent ratio (LER) and grain quality were enhanced in the intercopped colonies. Results
    suggested that suitable maize intercropping with different genotypes would increase the activities of SOD, POD and CAT of
    leaf, prolong leaf life, increase yield and improve quality.
    EFFECT OF ELEVATED ATMOSPHERIC CO2 CONCENTRATION AND LEVEL OF NITROGEN FERTILIZER ON ROOT RESPIRATION AND BIOMASS OF WINTER WHEAT
    KOU Tai-Ji, ZHU Jian-Guo, XIE Zu-Bin, LIU Gang, ZENG Qing
    Chin J Plan Ecolo. 2008, 32 (4):  922-931.  doi:10.3773/j.issn.1005-264x.2008.04.022
    Abstract ( 2679 )   PDF (423KB) ( 1270 )   Save
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    Aims Understanding belowground processes will help in determining the potential feedback of soil C storage on
    increased atmospheric CO2 concentration. Information on root respiration and biomass are important for understanding
    implications of environmental change on soil carbon cycling and sequestration. Because cropland is an important terrestrial
    ecosystem within the global climate change context, separately quantifying the response of crop root respiration and biomass
    to CO2 enrichment has important implications for agro-ecosystems, for predicting the magnitude and direction of soil C
    feedbacks. We observe them in a field experiment and evaluate the potential effect of elevated atmospheric CO2 concentration.
    Methods We used a free-air carbon dioxide enrichment (FACE) system and static chamber-GC (gas chromatography) method to
    study the effects of elevated atmospheric CO2 concentration and nitrogen fertilizer on root respiration and biomass of wheat
    (Triticum aestivum cv Yangmai 14) during two consecutive seasons, determined by a novel split root growth and gas collection
    system.
    Important finding Both elevated CO2 concentration and high nitrogen (HN, 148.1 mg N&#8226;kg-1 dry soil weight) application
    enhanced above- and belowground biomass in three different growth stages. The increase in belowground biomass under elevated
    CO2 concentration favors more residual roots to revert to field. Elevated CO2 concentration significantly stimulated root
    respiration at the booting-heading stages, which increased by 33.8% and 43.9% in 2004–2005, and by 23.8% and 28.9% in 2005–
    2006 in both high and low nitrogen (LN, 88.9 mg N&#8226;kg-1 dry soil weight) application, respectively, and significantly
    depressed root respiration at the late of filling stage by 31.4% and 23.3% in 2004–2005, and by 25.1% and 18.5% in 2005–
    2006 in both HN and LN treatments, respectively; however, no significant effect was found at the jointing stage. High
    nitrogen application promoted more root respiration than low nitrogen. While a significantly negative liner correlation
    between root respiration rate and belowground biomass was observed, the R2 of correlative coefficient under elevated CO2
    concentration was small, which showed elevated CO2 concentration reduced the correlation of both root respiration and
    accumulation of belowground biomass with wheat growing.

    MORPHOLOGY AND ACTIVITY OF ECTOMYCORRHIZAL FUNGI IN VITRO AND IN SYMBIONT WITH PINUS THUNBERGII
    ZHENG Ling, WU Xiao-Qin
    Chin J Plan Ecolo. 2008, 32 (4):  932-937.  doi:10.3773/j.issn.1005-264x.2008.04.023
    Abstract ( 3213 )   PDF (875KB) ( 1252 )   Save
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    Aims The fungal vacuole plays a key role in nutrient transportation and storage, especially in ectomycorrhizal symbionts. Our objective was to explore the effects of fungal activity and vacuole structure changes on host plant growth to further understand the mechanism of growth-promotion of mycorrhizal fungi and coevolution between host plant and mycorrhizal fungi.
    Methods Hyphae of ectomycorrhizal fungi Rhizopogen luteous (Rl), Pisolithus tinctorius (Pt2), and Boletus edulis (Be) cultured in vitro were stained with 6-CFDA, and the morphologies of fungal vacuoles and their activities were examined. Frozen sections of the ectomycorrhizal symbiont formed by the three fungi and Pinus thunbergii seedlings were stained and observed in the same way.
    Important findings Dispersive large vacuoles in hyphae of Pt2 and Rl and many small dense vacuoles in the hyphae of Be were observed in fungi cultured in vitro, and some vacuoles of Rl and Be linked into tubular vacuole systems. The activity of Be hyphae was higher than Pt2 and Rl, and Be grew faster than the other two. After ectomycorrhizal formation, P. thunbergii seedlings with Pt2 or Rl grew better than those with Be, and the fungal activities vacuole morphologies had changed greatly. Hyphae in mantles and Hartig nets of ectomycorrhiza formed by Pt2 and Rl showed higher activities than those formed by Be, which were hard to label, and tubular vacuole systems were observed sometimes in the hyphae of Hartig nets of Pt2 and Rl symbionts. It appears that fungal activity and tubular vacuole systems are related to the growth of P. thunbergii seedlings.
    EVALUATION OF GENETIC DIVERSITY BY SSR MARKERS FOR NATURAL POPULATIONS OF WILD SOYBEAN (GLYCINE SOJA) GROWING IN THE REGION OF BEIJING, CHINA
    YAN Mao-Fen, LI Xiang-Hua, WANG Ke-Jing
    Chin J Plan Ecolo. 2008, 32 (4):  938-950.  doi:10.3773/j.issn.1005-264x.2008.04.024
    Abstract ( 2838 )   PDF (572KB) ( 1572 )   Save
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    Aims Wild soybean (Glycine soja) is commonly accepted as the progenitor species of the cultivated soybean (Giycine max). It contains many characters potentially valuable for supplementing the soybean germplasm pool, yet little research has been done on genetic diversity in natural populations of wild soybean in China. Our objective was to evaluate genetic diversity in natural populations of wild soybean growing in the region of Beijing, China.
    Methods We sampled ten representative natural populations in 2005. Every sampled population consisted of 28-30 individuals and was over 10 m apart. Forty public SSR primer pairs over the 20 linkage groups were applied to evaluate genetic diversity.
    Important findings A total of 526 alleles (bands) were detected with an average number of 13.15 per locus. Mean expected heterozygosity per locus (He) was 0.369 for the populations, and the mean Shannon index (I) for the populations was 0.658. Mean observed heterozygosity per locus (Ho) for the populations was 1.29%. Between-population genetic diversity (Hs) averaged 0.446, and within-population genetic diversity (DST) averaged 0.362. Mean coefficient of gene differentiation for loci (GST) in the populations was estimated to be 0.544. This study showed that the center-western ecotype had higher genetic diversity than the northern and eastern ecotypes and that there appeared to be ecogeographically genetic divergence in the natural populations between the Taihang and the Yanshan mountains. A strongly drought-tolerant population had very low genetic diversity, and its tolerance gene(s) may be exploited for breeding.
    REVIEW ON THE MECHANISM MODELS OF ALLOMETRIC SCALING LAWS: 3/4 VS. 2/3 POWER
    HAN Wen-Xuan, FANG Jing-Yun
    Chin J Plan Ecolo. 2008, 32 (4):  951-960.  doi:10.3773/j.issn.1005-264x.2008.04.025
    Abstract ( 2840 )   PDF (407KB) ( 2625 )   Save
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    Allometric scaling relations are characteristic of all organisms. A challenging task is how the typical allometric scaling relationship—Kleiber’s Law, which depicts the proportionality between the metabolic rate of an animal and its body mass raised to the 3/4 power and is well established and supported by data—can be predicted from a purely theoretical standpoint. Scientists have proposed diverse models to do this, but almost all of the models are criticized for theoretical or methodological difficulties. However, ecologists and physicists recently proposed new models. Here we highlight the Fractal-Like Distribution Network Models and other models, such as Multi-Causes Model, Minimal Overall Entropy Production Model, Constructal Theory, Cell Model and Energy Consumption Model.
    RECENT ADVANCES IN H218O ENRICHMENT IN LEAF WATER
    WEN Xue-Fa, ZHANG Shi-Chun, SUN Xiao-Min, YU Gui-Rui
    Chin J Plan Ecolo. 2008, 32 (4):  961-966.  doi:10.3773/j.issn.1005-264x.2008.04.026
    Abstract ( 2587 )   PDF (371KB) ( 753 )   Save
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    There is considerable interest in the use of atmospheric C18O16O and 18O16O as a tracer for resolving the role of
    the terrestrial biosphere in the global carbon cycle. Leaf transpiration will result in the enrichment of the heavy H218O
    isotopes. The δ18O of leaf water at the evaporating site in the stomatal cavity directly influences the C18O16O and 18O16O
    exchanges, instead of that of the bulk leaf water. How to best quantify this enrichment effect remains an active area of
    research. In the past, a closed form of the Craig-Gordon model was obtained by invoking the steady-state assumption (δ18O of
    the transpired water is identical to δ18O of the xylem water). For the purpose of verification, the predictions of Craig-
    Gordon model are compared with δ18O of the bulk leaf water after appropriate corrections for the Péclet effect. On small
    time scales of minutes to hours, δ18O of the transpired water is variable in field conditions, implying that the steady
    state assumption is invalid. Recently, in-situ δ18O and δD measurement technology has been developed that has potential for
    improving our understanding of isotopic exchanges between the Earth’s surface and the atmosphere. The precision of hourly δ
    18O and δD is comparable to the precision of mass spectrometry. It has the potential to improve prediction of δ18O of leaf
    water at the evaporating site within the stomatal cavity for the temporal dynamics of atmospheric water vapor δ18O and the
    δ18O of the transpired water, especially if its measurement is made in a non-destructive manner and on a continuous basis.
    Because the isotopic flux of δ18O and δD is influenced by a similar set of biological and meteorological variables,
    simultaneous observations of δ18O and δD will provide additional constraints on the hydrological and ecological processes
    of the ecosystem. We review the theory and measurement techniques for the enrichment of H218O in leaves and focus on the
    recently developed in-situ measurement technology and its potential for improving our understanding of H218O enrichment in
    leaf water and C18O16O and 18O16O exchanges between the ecosystem and atmosphere.
    VEGETATION MONITORING AND TREND ANALYSIS: DISCUSSIONS ON QUANTITATIVE VEGETATION ECOLOGY
    BAI T. Jay, LIANG Ying-Quan
    Chin J Plan Ecolo. 2008, 32 (4):  967-976.  doi:10.3773/j.issn.1005-264x.2008.04.027
    Abstract ( 2472 )   PDF (350KB) ( 835 )   Save
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    Vegetation monitoring is important. This paper introduces a trend analysis method for vegetation sciences. A unit
    of homogeneous vegetation can be treated as a point, so it can have dynamic analysis. However, to carry enough information,
    this point has to be put into multi-variable space. Vegetation can be expressed as a position vector in multidimensional
    space. Vegetation is a resource competing system. All plant species compete for limited resources, and demands of all species
    can not exceed available resources. This can be expressed as the sum of the squares of all species equals one. Therefore, all
    the complementary plant species can be treated as mutually orthogonal. When using position vectors to represent vegetation,
    the magnitudes of the vectors carry information of the total biomass, while the directions of the vectors carry information
    of composition of vegetation; thus, the position vectors have to be standardized. Vegetation growth based on cell duplication
    is expressed as exponential growth. Changing trend is defined as present state over the past. The trend can be used to
    monitor the vegetation changes and to predict future states. Kalman filter is used to increase accuracy and lower monitoring
    cost.

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