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Table of Content
    Volume 39 Issue 6
    01 June 2015

    A Rhizophora stylosa population in the National Nature Reserve of Dongzhai Harbor of Hainan Province. Deng et al. studied the variations in the secondary wood anatomy in six R. stylosa populations with changing soil physicochemical properties and their implications to ecological adaptation (Pages 604–615 of this i ssue). (Photographed by DENG Chuan-Yuan)

      
    Orginal Article
    Mechanisms underlying the effects of fall dormancy on the cold acclimation and winter hard- iness of Medicago sativa
    LIU Zhi-Ying,LI Xi-Liang,LI Feng,WANG Zong-Li,SUN Qi-Zhong
    Chin J Plan Ecolo. 2015, 39 (6):  635-648.  doi:10.17521/cjpe.2015.0061
    Abstract ( 630 )   HTML ( 10 )   PDF (495KB) ( 1091 )   Save
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    As a global planting forage legume, alfalfa (Medicago sativa) is a valuable material to study the evolutionary and ecological mechanisms on plant adaptation to freezing due to their contrasting winter hardiness induced by fall dormancy (FD). This paper reveals that FD is an important growth characteristic that is adaptative to short-day and reducing temperature in late autumn, followed by a higher overwintering rate. Alfalfa cultivars are grouped into 11 FD ratings (numbered from 1 to 11), and this phenomenon is related to the extensive spread and cultivation for thousands of years in the globe. Alfalfa cultivars are under different climate habitats for a long time, leading to FD adaptive evolution, which provides rich genetic resources for human. In general, adaptative process associated with cold acclimation and winter hardiness in alfalfa is affected by FD, thus differences in winter hardiness exist among alfalfa cultivars. So far, regulation of FD by light and temperature and effects of FD on physiological and ecological processes involved in cold acclimation have been reported largely. However, signal transduction and the regulatory network associated with gene expression, especially the molecular mechanisms by which antifreeze proteins function in cold adaptation, are still poorly understood. Several scientific problems that need to be addressed in the future studies are highlighted in this review.

    Potential analysis of grass endophytes Neotyphodium as biocontrol agents
    LI Xiu-Zhang,YAO Xiang,LI Chun-Jie,NAN Zhi-Biao
    Chin J Plan Ecolo. 2015, 39 (6):  621-634.  doi:10.17521/cjpe.2015.0060
    Abstract ( 636 )   HTML ( 0 )   PDF (354KB) ( 971 )   Save
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    Many grasses in the subfamily Pooideae develop symbioses with Neotyphodium fungal endophytes, which exist widely in nature. The stably symbiotic relationship not only ensures accessible nutrients required by Neotyphodium fungal endophytes, but also significantly increases the resistance of host grasses to biological stresses through the production of secondary metabolites. Previous studies show that infected grasses with endophytic fungi have prominently enhanced resistance to pests, plant diseases, companion plants and other biological stresses. Grass endophytic fungi show remarkable resistant to at least 79 species of pests from three classes; arachnida, nematode and insecta, and to at least 22 species of pathogenic fungi. Although the biotechnological application of endophytic fungi in grass breeding for variety selection and quality improvement has progressed well, opportunities remain for further exploring the use of fungal endophytes among different host grasses coupled with the examination of genetic stability of Neotyphodium in novel host grasses. In the future application of endophytic fungi as a bio-control method, researchers should not only consider specificities of host grasses, but also need to have comprehensive analysis and knowledge about the mutual relationships among grasses, endophytic fungi and ecological environments, which will help use endophytic fungi to better serve humanity.

    Ecological wood anatomy of Rhizophora stylosa
    DENG Chuan-Yuan,ZHENG Jun-Ming,ZHANG Wan-Chao,GUO Su-Zhi,XUE Qiu-Hua,YE Lu-Ying,SUN Jian-Wen
    Chin J Plan Ecolo. 2015, 39 (6):  604-615.  doi:10.17521/cjpe.2015.0058
    Abstract ( 627 )   HTML ( 0 )   PDF (1724KB) ( 804 )   Save
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    <i>Aims</i>

    Mangrove forest is desirable for studying variations in wood structure along an ecological gradient because mangroves are subjected to considerable habitat changes apart from salt stress within a small area. To elucidate the adaptive capability of wood structures towards fluctuating environmental conditions, variations in wood structures were investigated in 18 individuals of Rhizophora stylosa representing 6 populations along a natural soil physicochemical gradient in the National Nature Reserve of Dongzhai Harbor, Hainan Province.

    <i>Methods</i>

    Soil physicochemical properties were determined at the sites of 18 sampling trees in six R. stylosa populations. The anatomical characteristics of the secondary xylem were studied in details in the 18 trees by means of light microscopy, laser scanning confocal microscopy, scanning electron microscopy and transmission electron microscopy. Variations in the quantitative wood anatomical features in R. stylosa were assessed in details. Relationships between soil physicochemical variables and the quantitative wood anatomical features were analyzed by means of statistical methods.

    <i>Important findings</i>

    Some common specialized wood structures were observed in R. stylosa growing in different habitats, suggesting that these features may function for safely conducting water under high negative pressure and are thus adaptive to intertidal habitats. These common features include the occurrence of: 1) some fibriform vessel elements and a few vasicentric tracheids; 2) vesturing in pits of vessels and helical structures on vessel walls; 3) growth rings; 4) starch grains in ray cells and septate fibers. The quantitative anatomical characteristics have great plasticity in response to heterogeneous habitats. Stepwise regression analyses revealed that the total salt, contents of Mn2+, Na+, Cl-, Ca2+, organic matters, and total phosphorus of soils, and soil pH all have significant effects on quantitative wood anatomical features. Variations in the quantitative wood anatomical features in R. stylosa growing at different sites are adaptive to fluctuating environmental conditions in the intertidal areas.

    Comparison of physiological and leaf morphological traits for photosynthesis of the 51 plant species in the Maqu alpine swamp meadow
    REN Qing-Ji,LI Hong-Lin,BU Hai-Yan
    Chin J Plan Ecolo. 2015, 39 (6):  593-603.  doi:10.17521/cjpe.2015.0057
    Abstract ( 699 )   HTML ( 1 )   PDF (436KB) ( 1143 )   Save
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    <i>Aims</i>

    Trait-based approaches are often widely used in ecological research to predict or explain the complex ecological processes at both individual and ecosystem levels. Leaf function with morphological and physiological traits can play important roles in plan growth, survival, reproduction in natural environments. The aim of this study is 1) to determine the differences of leaf traits between both the species and the functional groups in a swamp meadow; 2) to explore the relationship between different leaf morphological traits and physiological traits.

    <i>Methods</i>

    Gas exchanges of 51 species (in 14 families) were measured on six fully expand health leaves (from different individual plants) using a portable photosynthesis system in the field during the peak of growing season. The leaf morphological traits was measured based on 6 single leaves form different individuals, include the net photosynthesis rate (Pn), transpiration rate (Tr), specific leaf area (SLA), relative leaf water content (LWC), leaf area (LA) and the water use efficiency (WUE = Pn/Tr).

    <i>Important findings</i>

    Result showed that there were significant interspecific differences in the investigated traits as described in above methods. Among the traits, the LWC (coefficient of variation, CV = 0.11) was ranged from 58.12% to 81.83%, 0.0088-0.0278 m2·g-1 for the SLA (CV = 0.27), and 0.51 cm2 to 100.90 cm2 for the LA (CV = 1.73), while the range of 4.25-19.23 μmol CO2·m-2·s-1, 2.89-12.81 mmol H2O·m-2·s-1 and 0.56-3.76 μmol CO2·mmol-1 H2O for Pn (CV = 0.33), Tr (CV = 0.33), and WUE (CV = 0.36), respectively. There were also significant differences between the functional groups (sedge, grass and forbs) for these traits. Forbs have larger LA and higher LWC than sedge and grass; Grass have higher WUE and SLA than those of others; while Sedge have higher Pn. Our result also showed there were high correlation between Pn and SLA, WUE and LWC, indicated the strong impacts of leaf morphology on the gas exchange physiology. The SLA was also related to gas exchange traits both among species and functional groups, while the LWC was only among species and LA among functional groups. In conclusion, significant differences in these functional traits among species suggest that these species could vary in resource use and growth form in their community ecosystem. Also the difference among the functional groups in these traits indicates the resource use of the community would be largely influenced by its species composition, especially the differences of functional groups. The research finding will help to better understanding of the ecosystem function in alpine swamp meadow with related management implication.

    Trade-off between root forks and link length of Melica przewalskyi on different aspects of slopes
    SONG Qing-Hua,ZHAO Cheng-Zhang,SHI Yuan-Chun,DU Jing,WANG Ji-Wei,CHEN Jing
    Chin J Plan Ecolo. 2015, 39 (6):  577-585.  doi:10.17521/cjpe.2015.0055
    Abstract ( 539 )   HTML ( 0 )   PDF (373KB) ( 1034 )   Save
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    <i>Aims</i>

    The number of root forks and link length influence distribution patterns of plant roots. The trade-off between root forks and link length has an important meaning for comprehending ecological adaptation strategy of root architecture. Our objective was to study the relationship between root forks and link length of Melica przewalskyi population in response to slope aspects in the northwest of China.

    <i>Methods</i>

    The study site was located in a degraded alpine grassland on the northern slope of Qilian Mountains, Gansu Province, China. Survey and sampling were carried out in 80 plots that were set up along four aspect transects of a hill with 20 m distance between adjacent plots. A handheld GPS was used to record latitude, longitude and altitude of each plot. ArcGIS was used to set up digital elevation model (DEM) to extract the information of elevation, aspect, and slope for each plot. The traits of plant communities were investigated and three individual samplings of M. przewalskyi were collected randomly in each plot. The samples were cleaned and divided into different organs. The roots were scanned with the Win-RHIZO for measurements of root forks and link length in laboratory, and biomass of different organs was measured after being dried at 80 °C in an oven. The 240 plots were categorized into groups of north, east, west and south aspects of slopes, and the linear regression analysis was then used to examine the trade-off relationship between root forks and link length in different groups.

    <i>Important findings</i>

    With a change of the aspect from north to east, west and south, the density, aboveground biomass, height and soil moisture content of the plant community displayed a pattern of steadily declining, while the density, height, root link length of M. przewalskyi increased, and the root forks decreased. The number of root forks was negatively correlated with the link length in all aspects, but the relationship varied along the aspect gradient (p < 0.05). There was a highly significant negative correlation (p < 0.01) between the root forks and link length on north slope and south slope, whereas less significant (p < 0.05) on the east slope and west slope, all indicating a trade-off relationship between the root forks and link length. Consequently, the patterns of resource allocation between root forks and link length in different slope habitats reflected the response and adaption of plant root functional traits to their biotic and abiotic environments and the investment balance mechanism for root architecture construction.

    Microclimate of forests across East Asia biomes: 1. Radiation and energy balance
    TAN Zheng-Hong,YU Gui-Rui,ZHOU Guo-Yi,HAN Shi-Jie,HSIA Yue-Joe,MAEDA Takashi,KOSUGI Yoshiko,YAMANOI Katsumi,LI Sheng-Gong,OHTA Takeshi,HIRATA Ryuichi,YASUDA Yukio,NAKANO Takashi,KOMINAMI Yuji,KITAMURA Kenzo,MIZOGUCHI Yasuko,LIAO Zhi-Yong,ZHAO Jun-Fu,YANG Lian-Yan
    Chin J Plan Ecolo. 2015, 39 (6):  541-553.  doi:10.17521/cjpe.2015.0052
    Abstract ( 674 )   HTML ( 2 )   PDF (928KB) ( 1062 )   Save
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    <i>Aims</i>

    Forest microclimate is the local environment generated through the interaction between regional climate and forest structure. Studies on forest microclimate not only have theoretical significances in ecology but also practical meanings in forest management practices and wood production. Radiation budget and energy balance is the basis for microclimate. Few studies have performed the radiatoin budget and energy balance analysis at regional scale. Here, we focused at this for the East Asia.

    <i>Methods</i>

    A total of 17 forest sites in the East Asia across biomes were used in this study. Measurements on solar radiation, long-wave radiation, net radiation, sensible heat flux, latent heat flux, and soil heat flux were compiled in the context of radiation and energy conservation. The annual variations of radiation and energy components were analyzed by site. Mean annual radiation and energy were related to latitude. The radiation and energy conservation equations were established for each forest biome by the multi-site block averages.

    <i>Important findings</i>

    Forest radiation properties (i.e. solar radiation, net radiation, albedo) showed a linear trend with latitude among the sites. For example, the solar radiation and latitude relationship is: y = 6205 - 42.15x (p < 0.01), indicating that solar radiation decreases with latitude at a rate of 42 MJ per degree with a theoretical maximum of 6205 MJ. A more significant relationship was found between net radiation and latitude: y = 4340 - 45.60x (r = -0.89, p < 0.0001). The radiation and energy budgets of boreal, temperate, subtropical and tropical forest were established. Evapotranspiration fraction (EF) was highly correlated with precipitation (P) as: EF = 0.7098(1 - exp(-0.0026P)) (R2 = 0.7451, p < 0.0001). Subtropical forest showed a unique pattern in this cross-biome analysis but needs further studies in the future.

    Characteristics of carbon sequestration during natural restoration of Maolan karst forest ecosystems
    HUANG Zong-Sheng,YU Li-Fei,FU Yu-Hong,YANG Rui
    Chin J Plan Ecolo. 2015, 39 (6):  554-564.  doi:10.17521/cjpe.2015.0053
    Abstract ( 576 )   HTML ( 0 )   PDF (406KB) ( 714 )   Save
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    <i>Aims</i>

    The objective of this study was to characterize the ecosystem carbon sequestration during natural restoration process of karst forest vegetation.

    <i>Methods</i>

    We adopted the “space for time” approach to examine the pattern of carbon sequestration in karst forest ecosystems along the natural restoration process. Forest vegetation types representing six typical successional stages were selected and investigated, which include herb stage, herb to shrub stage, shrub stage, shrub to arbor stage, arbor stage, and climax stage. Twenty-four plots of 30 m × 30 m were established on sites of the six forest types, and samples of plants, litter and soil were collected in each plot.

    <i>Important findings</i>

    The total vegetation biomass increased from 7.97 to 166.83 t·hm-2 with advancement of restoration stages, corresponding to the trend of changes in biomass for the arbor layer (from 41.77 to 164.59 t·hm-2), but with declining biomass for the herb layer (from 8.45 t·hm-2 at the herb to shrub stage to 0.68 t·hm-2 at the climax stage) and the shrub layer (from 32.87 t·hm-2 at the shrub stage to 1.56 t·hm-2 at the climax stage). The ratio of above ground to belowground biomass in karst vegetation was relatively low (varying between 1.26 and 2.03), especially for the shrub layer (varying between 1.23 and 1.45). The weighted average carbon content increased from 36.76% to 48.74% with the process of restoration. In the process of the natural restoration, the carbon density in the arbor layer increased from 19.44 to 80.40 t·hm-2, but decreased from 3.19 t·hm-2 at the herb to shrub stage to 0.23 t·hm-2 at the climax stage in the herb layer and from 15.13 t·hm-2 at the shrub stage to 0.69 t·hm-2 at the climax stage in the shrub layer. The overall carbon density showed an increasing trend from the early stages (herb and herb to shrub stages), through the middle stages (shrub and shrub to arbor stages), to the late stages (arbor and climax stages) at levels of ecosystems (from 15.72 to 99.37 t·hm-2), vegetation (from 2.93 to 81.31 t·hm-2), and soil (from 8.26 to 18.80 t·hm-2), accompanied by a reduction in litter (from 4.97 to 1.53 t·hm-2). It can be concluded that vegetation, especially the component of woody plants, has the greatest influence on ecosystem carbon stocks during the recovery progress of karst forests, with little effects of soils. Therefore, it is important to facilitate the recovery of vegetation for enhancing karst ecosystem carbon sink.

    Effects of light and water depth on seed germination of Phragmites australis in the wetlands of Songnen Plain
    LIU Bo,LÜ Xian-Guo,JIANG Ming,ZHANG Wen-Guang,WU Hai-Tao
    Chin J Plan Ecolo. 2015, 39 (6):  616-620.  doi:10.17521/cjpe.2015.0059
    Abstract ( 632 )   HTML ( 1 )   PDF (345KB) ( 778 )   Save
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    <i>Aims</i>

    Excessive growth of undesired plants, including ruderal natives and tall wetland species, posts great threat to wetland restoration. In this study, we examined the seed germination of Phragmites australis, an undesired species, to evaluate its impact on the restoration of desired Scirpus planiculmis and to provide scientific basis for vegetation management in Momoge wetland.

    <i>Methods</i>

    The germination experiment was conducted in incubators to examine the effects of light intensity (full light, green shade and dark environment) and water depth (0, 5, 15 and 30 cm), based on field observation, on seed germination of P. australis.

    <i>Important findings</i>

    Percentage germination of P. australis was significantly higher under “green shade” or “dark” environment than under “full light”. The species had the highest germination rate (86.67% ± 2.36%) at 0 cm water depth under the three light conditions. The interaction between light intensity and water depth on seed germination was significant (p < 0.05) indicating that under different light conditions, increase of water depth decreased seed germination rates at different degrees. We recommend to remove the litter and P. australis to increase light penetration, and to maintain a stable water depth for effectively inhibiting the regeneration of Phragmites and enhance the restoration of S. planiculmis.

    Effects of enclosure and grazing on carbon and water fluxes of sandy grassland
    SUN Dian-Chao,LI Yu-Lin,ZHAO Xue-Yong,ZUO Xiao-An,MAO Wei
    Chin J Plan Ecolo. 2015, 39 (6):  565-576.  doi:10.17521/cjpe.2015.0054
    Abstract ( 549 )   HTML ( 0 )   PDF (616KB) ( 898 )   Save
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    <i>Aims</i>

    Carbon and water cycling are two key processes in circulation of materials and energy flow of sandy grassland ecosystem; recognition of changes in carbon and water cycling is important for understanding the responses of sandy grassland ecosystem structure and function to regional climate change and human activities. Our objectives were to determine the regulations of carbon sequestration and emission, and to examine the relationships of carbon and water fluxes with environmental factors.

    <i>Methods</i>

    Chamber method was used to measure carbon and water fluxes in grazed plots and fencing enclosures of different durations in a sandy grassland over a growing season in 2013.

    <i>Important findings</i>

    (1) Variance analysis revealed that, during the observational period, the gross ecosystem productivity (GEP), ecosystem respiration (ER), and evapotranspiration (ET) were all in an order of: 17-year enclosure > 22-year enclosure > grazing, with significant differences (p < 0.05) among the treatments; the maximum values were 2.23, 1.65, and 1.94 times of the minimum values, respectively. (2) There was a significant linear and positive correlation between GEP and ET (p < 0.01); ET explained 58% to 60% of the variations in GEP. Water use efficiency (WUE) decreased from 2.85 μmol·nmol-1 in the 22-year enclosure to 2.75 μmol·nmol-1 in the 17-year enclosure, and to 2.10 μmol·nmol-1 in grazed plots. (3) There were significant linear and positive correlations between GEP, ER and soil water content. Exponential model better fitted the responses of ecosystem respiration to soil temperature. The temperature sensibility coefficient Q10 values of ER ranked in the order of 17-year enclosure (1.878) > 22-year enclosure (1.733) > grazing (1.477). In conclusion, enclosure enhanced the carbon and water cycling in degraded sandy grassland ecosystem. However, a 22-year enclosure is not beneficial to this process than 17-year enclosure, suggesting that proper enclosure is conductive to the recovery of degraded sandy grassland and effective to the use of sandy grassland resources.

    A comparison of multivariate regression tree and two-way indicator species analysis in plant community classification
    ZHANG Wen-Jing,ZHANG Qin-Di,WANG Jing,FENG Fei,BI Run-Cheng
    Chin J Plan Ecolo. 2015, 39 (6):  586-592.  doi:10.17521/cjpe.2015.0056
    Abstract ( 781 )   HTML ( 2 )   PDF (345KB) ( 1109 )   Save
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    <i>Aims</i>

    Multivariate regression tree (MRT) is a new statistical technique for plant community classification. Studies on advantages of MRT were still insufficient. Our objective was to compare the results of MRT with two-way indicator species analysis (TWINSPAN), which is widely used in recent years, and to provide suggestions for choosing an appropriate classification method.

    <i>Methods</i>

    We used both MRT and TWINSPAN to classify the forest communities in the southern part of Lüliang Mountain. The MRT analysis gave a tree with the splits based on additional environmental factors. The degree of consistency between the two classifications are compared through the coherence coefficient.

    <i>Important findings</i>

    (1) MRT divided 41 forest quadrats into four formations: the Platycladus orientalis formation, Acer davidii formation, Quercus wutaishanica formation and Diospyros kaki formation. The types of the formations are consistent with the analysis results from TWINSPAN. (2) Based on the quadrats that compromise the formations, these two methodologies provided a relatively high consistency, with the coherence coefficient up to 80.5%. (3) Compared with the TWINSPAN, the MRT can be seen as a form of constrained classification analysis that can relate different aspects of species composition to environmental data, so the clusters defined by the MRT define community types of the ecotone in an objective manner not available in other techniques. Finally, the TWINSPAN is a very effective classification technique in plant ecology research. However, the MRT has advantage over the TWINSPAN in terms of classifying continuous or transitional quadrats.


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