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Table of Content
    Volume 37 Issue 1
    01 January 2013

    Hilly and gully region landscape of the Loess Plateau, with Caragana korshinskii and Hippophae rhamnoides plants in the slope surface, where Jian et al. investigated the water-holding capacity by canopy of C. korshinskii and H. rhamnoides (Pages 45–51 of this issue) (Photographed by FANG Shu-Min).

      
    Research Articles
    Relationship analysis between soil moisture in root zone and top-most layer in China
    LIU Su-Xia, XING Bo, YUAN Guo-Fu, MO Xing-Guo, and LIN Zhong-Hui
    Chin J Plan Ecolo. 2013, 37 (1):  1-17.  doi:10.3724/SP.J.1258.2013.00001
    Abstract ( 1391 )   PDF (1100KB) ( 1650 )   Save
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    Aims It is more difficult to determine soil moisture in root zones (RSM) than soil moisture in the top-most layer (TSM). The relationship between TSM and RSM based on point A is useful for acquiring RSM at point B from its TSM if the relationship between TSM and RSM is general. The general relationships established so far have been based on only one crop or one ecosystem. Our aims are to determine the general relationship between TSM and RSM in China over various crops and ecosystems and to explore the effects of ecosystem, soil property, precipitation, vegetation, soil thickness and the order of magnitude of soil moisture on the relationship.
    Methods We used 3 437 pairs of TSM and DSM data from 31 stations at 109 observation sites. The data represent all the terrestrial ecosystems, including forest, grass, agriculture, desert and mire, in 2006 from the China Ecosystem Research Network. We used linear regression in mathematics and effect analysis in physics to study the general relationship between TSM and RSM and to determine the influence of ecosystem, soil property, precipitation, vegetation, soil thickness, the order of magnitude of soil moisture on the relationship. The data are divided into calibration and verification groups for producing the relationship.
    Important findings There is generally a linear relationship between TSM and RSM. The coefficient of determination (R2) between RSM and TSM is high for forest and mire ecosystems (R2 > 0.79 for both calibration and verification), intermediate for agricultural (R2 > 0.80 for calibration and 0.70 for verification) and grass ecosystems (R2 > 0.80 for calibration and 0.50 for verification) and low for desert ecosystem (R2 = 0.62 for calibration and 0.49 for verification). The effect of soil properties on the relationship is similar to that of ecosystem, with mire ecosystem corresponding to meadow soil with white pulp, desert ecosystem corresponding to aeolian soil, grass ecosystem corresponding to sandy-loam and sandy soil, forest ecosystem corresponding to loam and agricultural ecosystem corresponding to various soil types. The spatial variability of the parameters for the relationship is very high for soil moisture within semi-humid, semi-arid and arid zones and low for humid zone. The relationship is similar among very-humid zone, loam and forest ecosystem. The effect of vegetation on the relationship can be divided into four categories: poor relationship due to the influence of vegetation itself, poor regional relationship due to the difference between the location sites of vegetation, good relationship at single point and good relationship over a region. It is not recommended to derive the RSM from TSM based on the relationship for the first two categories. It is suitable to use the relationship only at single point for the third category. And it is practicable to use the regional relationship to derive RSM from TSM for the fourth category. Correlation is higher between TSM and RSM where the soil layer is thicker. The R2 can remain as high as 0.79 when the soil
    layer is as thick as 100 cm. By scaling the original soil moisture data with maximum value, it is found there is no effect of the order of the magnitude of soil moisture on the relationship.

    Research on vegetation cover information extraction technologies under different terrain conditions
    WU Jian, LIU Min-Shi, and LI Wei-Tao
    Chin J Plan Ecolo. 2013, 37 (1):  18-25.  doi:10.3724/SP.J.1258.2013.00002
    Abstract ( 770 )   PDF (261KB) ( 1158 )   Save
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    Aims We compared a variety of vegetation cover extraction methods by hyperspectral remote sensing that are currently popular. Our aims were to systematically study vegetation information extraction technology and provide a reference for further study of vegetation cover.
    Methods The methods of vegetation index, dimidiate pixel model, principal component regression (PCR), partial least squares regression first order differential (PLSR) and linear spectral mixture decomposition model were used to extract vegetation information.
    Important findings The vegetation cover estimation ability of dimidiate pixel models established by different normalized differential vegetation index (NDVI) was higher than that of the regression models established by NDVI directly. The optimization model for shady slopes was PLSR model based on the first order differential (FD) with modeling R2 = 0.810, root mean square error (RMSE) = 6.29 and validation R2 = 0.773, RMSE = 8.85. The optimization model for sunny slopes was PLSR model based on the second order differential (SD), with modeling R2 = 0.823, RMSE = 6.04 and validation R2 = 0.801, RMSE = 7.35. The optimization model for plains was full confine linear spectral mixture model (FCLS), with validation R2 = 0.852, RMSE = 5.86.

    Environmental factors correlated with species diversity in different tropical rain forest types in Jianfengling, Hainan Island, China
    XU Han, LI Yi-De, LUO Tu-Shou, CHEN De-Xiang, and LIN Ming-Xian
    Chin J Plan Ecolo. 2013, 37 (1):  26-36.  doi:10.3724/SP.J.1258.2013.00003
    Abstract ( 763 )   PDF (462KB) ( 1503 )   Save
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    Aims Environmental factors are key factors impacting species distribution and determining species richness. An important question is whether the major environmental factor are the same in old-growth forests and secondary forests produced by logging. This question is very important for monitoring long-term changes in secondary tropical rain forests.
    Methods A unique, robust data set consisting of 164 625 m2 quadrats in a 160 km2 tropical rainforest was set up from August 2007 to June 2009 in the middle of the Jianfengling Natural Reserve, Hainan Island, China. Forest logging history was determined and 17 environmental factors were measured for each quadrat. First, we analyzed the relationship among these 17 factors. Then, these quadrats were classified into three forest types with different logging history: old-growth forests, diameter-limit logged forests and clear-cut forests. Canonical correspondence analysis (CCA) was used to analyze the environmental factors impacting species distributions. Step-forward multiple regression was used with and without considering spatial autocorrelation in the data set to disclose which environmental factors determined species richness.
    Important findings The environmental factors impacting species distribution and determining species richness changed because of differences of forests logging history. Elevation is the second most important factor influencing patterns of species diversity. CCA showed that species distribution in old-growth forests is closely related to elevation, soil exchangeable calcium content, soil exchangeable magnesium content and four soil physical factors (soil density, maximum water holding content, capillary water-holding content and capillary porosity). Importance of soil total phosphorous content and available phosphorous content was greater in logged forests, but the importance of soil exchangeable calcium content and exchangeable magnesium content was lower in clear-cut forests. Multiple regression analysis also showed that species richness was significantly correlated with elevation and soil exchangeable calcium in the old-growth forests. While species richness was correlated with elevation, soil total phosphorous content and soil available potassium content in the diameter-limit logged forests and was only correlated with elevation in the clear-cut forests. Furthermore, it is suggested it is better to compare the spatial autocorrelation models with other models to describe the relationship between environmental factors and species richness, even it does not always exist in the ecological data set with spatial characteristics.

    Effects of greenbelt width on air temperature and humidity in urban river corridors
    JI Peng, ZHU Chun-Yang, and LI Shu-Hua
    Chin J Plan Ecolo. 2013, 37 (1):  37-44.  doi:10.3724/SP.J.1258.2013.00004
    Abstract ( 670 )   PDF (503KB) ( 1041 )   Save
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    Aims Our purpose is to provide a scientific basis for the construction of urban river corridors. We analyzed the effects of different widths of urban river greenbelts on air temperature and humidity.
    Methods We studied eight greenbelts with different widths along the fifth ring in Beijing, China during one year. We measured air temperature and relative humidity of the greenbelts near the river and at a control location every two hours from 8:00 to 18:00 for seven continuous days in each season.
    Important findings The greenbelt width affected the decrease of temperature and increase of humidity in spring, summer and autumn, and the effect increased with greater width. The effect was strongest on temperature and humidity in summer, and there was little difference between spring and autumn. The greenbelt affects the increase of temperature and decrease of humidity in summer. The temperature effect increased and the humidity effect decreased with greater width. The effects of different greenbelt widths on temperature and humidity were related to ambient temperature. It is greatest during the time that temperature was highest (14:00–16:00). The effect of greenbelt width on the decrease of temperature and increase of humidity was strongest in spring, summer and autumn, while the effect on the increase of temperature was weakest and decrease of humidity was strongest in winter.

    Water storage capacity of the canopy dominated by Caragana korshinskii and Hippophae rhamnoides in hilly and gully region on the Loess Plateau of Northwest China
    JIAN Sheng-Qi, ZHAO Chuan-Yan, FANG Shu-Min, YU Kai, and MA Wen-Ying
    Chin J Plan Ecolo. 2013, 37 (1):  45-51.  doi:10.3724/SP.J.1258.2013.00005
    Abstract ( 655 )   PDF (388KB) ( 1453 )   Save
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    Aims Our objective is to study the canopy water storage capacity of shrubs, a key factor controlling rainfall interception, which affects a variety of hydrological processes in water-limited arid and semi-arid ecosystems. Vast areas of revegetated desert ecosystems in northwestern China are occupied by shrub and dwarf shrub communities. Yet, data are scarce regarding their rainwater storage capacity.
    Methods From May to October 2011, the methods of Pereira regression and direct measurement were used to research water storage capacity by the interception data and water storage capacity of each component of Caragana korshinskii and Hippophae rhamnoides, the main artificial afforestation tree species in the Loess Plateau.
    Important findings There were some differences among the two methods due to effects of different factors. The regression analysis was mainly impacted by the measurement approaches of throughfall and leaf area index (LAI), with the maximum water storage capacity of 0.68 mm and 0.72 mm for C. korshinskii and H. rhamnoides, respectively. The direct measurement was mainly impacted by the canopy structure; the maximum water storage capacity was estimated to be 0.73 mm and 0.76 mm for C. korshinskii and H. rhamnoides, respectively. The direct measurement showed that the maximum water storage capacity per unit area of the canopy components was in the order of branches (0.31 mm) > leaves (0.27 mm) > trunks (0.15 mm) for C. korshinskii, and trunks (0.33 mm) > branches (0.29 mm) > leaves (0.14 mm) for H. rhamnoides.

    Genetic diversity of central and peripheral populations of Toona ciliata var. pubescens, an endangered tree species endemic to China
    LIU Jun, JIANG Jing-Min, ZOU Jun, XU Jin-Liang, SHEN Han, and DIAO Song-Feng
    Chin J Plan Ecolo. 2013, 37 (1):  52-60.  doi:10.3724/SP.J.1258.2013.00006
    Abstract ( 781 )   PDF (294KB) ( 1255 )   Save
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    Aims Our objective was to elucidate the genetic diversity of central and peripheral populations of Toona ciliata var. pubescens and whether there existed “central-peripheral hypothesis” in these populations.
    Methods We analyzed 384 individuals from nine natural populations using eight pairs of polymorphic SSR primers.
    Important findings The mean number of observed and expected number of alleles in peripheral populations were not lower, but higher than those in central populations. Common widespread and rare local alleles were distributed in all populations, but common local and rare widespread alleles were found in five and three populations, respectively. Both the observed and expected heterozygosities were higher compared to the central populations. The coefficient of gene differentiation of the peripheral populations was 0.304 5, which was significantly higher than that of the central populations (FST = 0.152). The gene flow between central populations was greater than one, but less than one between peripheral populations. These indicated that frequent gene flow existed between central populations, while terrain and fragmentation prevented gene flow among peripheral populations. Mantel test indicated no relationship was found between genetic and geographical distance of T. ciliata var. pubescens.

    Phenotypic diversity of pods and seeds in natural populations of Gleditsia sinensis in southern China
    LI Wei, LIN Fu-Rong, ZHENG Yong-Qi, and LI Bin
    Chin J Plan Ecolo. 2013, 37 (1):  61-69.  doi:10.3724/SP.J.1258.2013.00007
    Abstract ( 737 )   PDF (256KB) ( 1466 )   Save
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    Aims Gleditsia sinensis is an endangered plant endemic to China. Our objectives were to determine 1) the phenotypic variation of pods and seeds in natural populations and 2) the relationship between phenotypic variation of natural population and different distribution areas in G. sinensis.
    Methods Field investigation and analysis of the natural distribution of G. sinensis in southern China led to our selection of six pod characters and five seed traits from 10 populations. We examined morphological diversity among and within populations based on analysis of eleven phenotypic traits. Variance analysis, multi-comparison and correlation analysis were used to analyze experimental results.
    Important findings Analysis of variance for all traits showed significant differences among and within populations. There was significant positive correlation between the pod, the seed and seed weight. The variation of pod traits within and among the populations was larger than those of seed traits. The mean phenotypic differentiation coefficient for the eleven traits was 20.42%, and the variation within populations (32.28%) was higher than that among populations (7.19%), which indicated that the variance within population was the main part of the phenotypic variation of the species. The range of variation of coefficient of variance (CV) among 11 traits was 4.55%–18.38%, and the average was 11.20%. The CV of pod within populations (14.75%) was higher than seed (6.95%), which means that the seed has higher stability. Most of the pod and seed traits were positively correlated. Both the seed and the pod were shown to have west-east variation at constant latitude. These findings offer basic data for further study of genetic breeding and conservation biology of this species.

    Inoculation two azotobacter enhancing osmotic stress resistance and growth in wheat seedling
    LIU Hua-Wei, LIN Xiao-Jun, SUN Chao, LI Qiang, YANG Hu, GUO Ai-Guang
    Chin J Plan Ecolo. 2013, 37 (1):  70-79.  doi:10.3724/SP.J.1258.2013.00008
    Abstract ( 833 )   PDF (396KB) ( 1473 )   Save
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    Aims The seedling stage is the key stage of matter and energy accumulation in the wheat life cycle. Therefore, drought during the seedling stage affects population formation in late stages. In this study, wheat seedlings were inoculated with azotobacters Azorhizobium caulinodans ‘ORS571’ and Azospirillum brasilense ‘Yu62’.
    Methods Wheat seedlings germination was screened in normal conditions and with PEG 6000 osmotic stress using seedlings inoculated with azotobacters. Root volume, relative water content (RWC), proline content and soluble protein content of seedling laminas were determined under PEG drought stress using seedlings inoculated with azotobacters on laminas.
    Important findings The germination rate of wheat seedlings was significantly increased under drought stress when inoculated with azotobacters. Moreover, wheat seedlings inoculated with mixed azotobacters have more obvious growth promotion than when inoculated with a single azotobacter. The former laminas proline content, relative water content, proline content and soluble protein content had increased. The results showed that drought resistance of wheat seedlings was improved when inoculated with mixed azotobacters, which provided the foundation for further study of azotobacter-wheat interaction under drought stress.

    Review
    Review of advances in carbon sequestration potential of agroforestry
    PING Xiao-Yan, WANG Tie-Mei, and LU Xin-Shi
    Chin J Plan Ecolo. 2013, 37 (1):  80-92.  doi:10.3724/SP.J.1258.2013.00009
    Abstract ( 837 )   PDF (289KB) ( 1702 )   Save
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    Agroforestry is regarded as a sustainable land-use management due to its potential for solving the problem of resource deficiency, improving the livelihood of rural areas and reducing environmental degradation. Agroforestry has attracted considerable scientific attention since the Kyoto Protocol because it has relatively high potential for carbon sequestration. Comprehensively understanding the process of carbon sequestration in agroforestry and its response to climate change, environmental variation and management practices is essential for predicting the carbon sequestration potential of agroforestry under varying climate and land-use patterns. This paper first reviews the concept and classification of agroforestry and then proposes the mechanism of higher carbon sequestration in agroforestry systems compared with monocropping or monoculture pasture systems. Furthermore, the methods used for quantifying the carbon sequestration potential of agroforestry and the present challenges are discussed. Based on the systematic review of previous studies, the effects of climatic factors, environmental conditions and management practices on carbon sequestration potential of agroforestry are illustrated. The carbon sequestration potential of agroforestry is relatively low in China compared with other regions around the world. In order to improve the carbon sequestration potential of agroforestry, future studies should focus on enlarging the area of agroforestry, developing appropriate designs and management of agroforestry, selecting appropriate species composition and optimizing the multi-layer structure of agroforestry.


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