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Table of Content
    Volume 37 Issue 3
    01 March 2013

    A typical landscape of karst cluster-peak depression in Mulun National Nature Reserve, Guangxi Zhuang Autonomous Region, China, where Du et al. studied plant community characteristics and their couplings relationship with soil (Pages 197–208 of this issue) (Photographed by PENG Wan-Xia).

      
    Research Articles
    Adaptation of biomass allocation patterns of wild Fritillaria unibracteata to alpine environment in the eastern Qinghai-Xizang Plateau
    XU Bo, WANG Jin-Niu, SHI Fu-Sun, GAO Jing, and WU Ning
    Chin J Plan Ecolo. 2013, 37 (3):  187-196.  doi:10.3724/SP.J.1258.2013.00019
    Abstract ( 853 )   PDF (743KB) ( 1754 )   Save
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    Aims Under different selection stresses, alpine plants tend to adjust their biomass investments to different functions and/or organs, and this biomass allocation strategy presents different patterns during different life history stages of plants. Our objective is to address three hypotheses regarding Fritillaria unibracteata: 1) elevation gradients impact individual bulb biomass and individual total biomass; 2) biomass allocation adapts to the elevational change of environmental factors; and 3) biomass allocation at different life history stages show different patterns.
    Methods We collected wild F. unibracteata at different elevations in the alpine belt of Songpan County in the eastern Tibetan Plateau. The samples were cleaned and divided into different organs, the biomasses of which were then weighed after being dried in the oven.
    Important finding Elevation significantly affected individual bulb biomass (IBB) and individual total biomass (ITB), both of which decreased gradually with increased elevation. Elevation representing the heat factor was the pivotal factor limiting the growth of alpine plants such as F. unibracteata. For plants with different life history
    stages, their biomass allocation presented diverse patterns. First, the bulb biomass allocation (BBA) of 2-year-old F. unibracteata significantly decreased with increased elevation, but its leaf biomass allocation (LBA) increased. Second, both BBA and LBA of 3- and 4-year-old F. unibracteata were relatively stable at different elevations, but their stem biomass allocation (SBA) significantly decreased with increased elevation. In contrast, the sexual reproductive (flower) allocation (SRA) significantly increased with increased elevation. Third, at different life history stages, the root biomass allocation (RBA) of F. unibracteata was relatively stable at different elevations. Both RBA and SBA showed an increasing trend with the growth of plants, but BBA and LBA showed a decreasing trend. Three- year-old individuals normally had the maximum IBB.

    Plant community characteristics and its coupling relationships with soil in depressions between karst hills, North Guangxi, China
    DU Hu, PENG Wan-Xia, SONG Tong-Qing, WANG Ke-Lin, ZENG Fu-Ping, LU Shi-Yang, SHI Wei-Wei, TANG Cheng, and TAN Qiu-Jin
    Chin J Plan Ecolo. 2013, 37 (3):  197-208.  doi:10.3724/SP.J.1258.2013.00020
    Abstract ( 850 )   PDF (311KB) ( 1715 )   Save
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    Aims Our objective was to study plant community characteristics and coupling relationships between plant and soil properties in different ecosystems in depressions between karst hills.
    Methods We established 24 sample plots of 20 m × 20 m dimensions in four ecosystems (grassland, scrub, secondary forest and primary forest) in depressions between karst hills. We investigated the species composition and diversity characteristics of these ecosystems. We chose 35 indexes covering plant community and soil properties to study the relationships between plant factors and soil nutrients, soil mineral chemical components and soil microbes using analysis by principal component analysis (PCA) and canonical correlation analysis (CCA).
    Important findings Along succession from grassland to scrub to secondary forest to primary forest, the maximum number of species, genera and families with importance values (IV) >10.00 and maximum species diversity were in secondary forest, and the optimal community structure was in primary forest. The depressions between karst hills had high landscape heterogeneity, and different ecosystems were influenced by different factors. Soil microbes were the dominant influence in karst fragile ecosystems, followed by scrub. CCA elucidated a close relationship between species diversity and soil nitrogen, Al2O3, Fe2O3, microbial biomass carbon (Cmic), fungi and bacteria. Vegetation improvement and management practices should focus on such characteristics of different ecosystems when undertaking restoration and reconstruction of karst fragile ecosystems.

    Allocation patterns of above- and belowground biomass in desert grassland in the middle reaches of Heihe River, Gansu Province, China
    WANG Min, SU Yong-Zhong, YANG Rong, and YANG Xiao
    Chin J Plan Ecolo. 2013, 37 (3):  209-219.  doi:10.3724/SP.J.1258.2013.00021
    Abstract ( 740 )   PDF (407KB) ( 1817 )   Save
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    Aims The allocation of above- and belowground biomass is highly meaningful in research of carbon storage and cycling in ecosystems. Our objective is to characterize biomass allocation patterns of desert grassland in the middle reaches of Heihe River, Gansu Province, China by providing a detailed study of allocation of above- and belowground biomass.
    Methods We used the quadrat survey method to study above- and belowground biomass of desert grassland in July–August, 2011. The allometric relationship between above- and belowground biomass was fitted by the method of reduced major axis (RMA) regression. The vertical distribution pattern of belowground biomass was simulated by the root vertical distribution model developed by Gale and Grigal in 1987.
    Important findings Above- and belowground biomass at the community level ranged from 3.2 to 559.2 g·m–2 and 3.3 to 188.2 g·m–2, respectively. Above- and belowground biomass of individuals varied from 6.1 to 489.0 g and 2.4 to 244.2 g, respectively. The ratios of root to shoot (R/S) at community and individual levels were 0.10 to 2.49 and 0.07 to 1.55, respectively. Therefore, the aboveground biomass was greater than belowground biomass at both levels, and the R/S ratio was higher at the community level. The slopes of the fitted equations at the community and individual levels were 1.100 1 and 0.991 3, respectively. Neither was significantly different from 1, which means the allocation patterns between above- and belowground biomass were similar at both levels and indicates an isometric allocation relationship between above- and belowground biomass. Belowground biomass was concentrated mainly in the 0–20 and 0–30 cm soil layers. Root biomass in the 0–20 cm soil depth accounted for 89.81% and 81.42% of the total root biomass at the community and individual levels, respectively. Parallel values for the 0–30 cm soil depth were 96.95% and 93.62%.

    First and second sets of shoots in five evergreen woody species from Tiantong National Forest Park of Zhejiang, China
    XIA Yang-Jie, TANG Jian-Qiang, ZHANG Guang-Fu, HUANG Chao, MENG Feng-Qun, and SUN Shu-Cun
    Chin J Plan Ecolo. 2013, 37 (3):  220-229.  doi:10.3724/SP.J.1258.2013.00022
    Abstract ( 633 )   PDF (298KB) ( 1128 )   Save
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    Aims Some woody species of subtropical evergreen broad-leaved forests in Eastern China form a second set of shoots in late summer or autumn after a first set in spring. Our objective is to elucidate features of this second set of shoots, including their adaptive significance.
    Methods We investigated differences between the first and second sets of shoots for five evergreen woody species (Symplocos lancifolia, Loropetalum chinense, Eurya rubiginosa var. attenuata, Myrica rubra, and Castanopsis fargesii) from an evergreen broad-leaved forest in Tiantong National Forest Park of Zhejiang, China. Herbivore damage of leaves was estimated, leaf emergence rate, leaf expansion rate and duration were calculated, and twig investment (leaf number and individual leaf area within twigs, twig stem length and diameter) was measured for both sets of shoots.
    Important findings Leaves of M. rubra and C. fargesii suffered greater herbivore damage to the second shoots compared with the first, and no significant difference was found in damage between the two sets of shoots for S. lancifolia, L. chinense and E. rubiginosa var. attenuata. The first and second sets of shoots shared the same leaf emergence pattern. Symplocos lancifolia, L. chinense, E. rubiginosa var. attenuata, and M. rubra showed a succeeding type of leaf emergence, and C. fargesii showed a flushing type of leaf emergence. However, duration of leaf emergence was much shorter in the second set of shoots for S. lancifolia, E. rubiginosa var. attenuata and M. rubra than in the first but not for the other two species. Leaf expansion rate was significantly higher for the second set of shoots for S. lancifolia, L. chinense and E. rubiginosa var. attenuata and was indistinguishable for M. rubra, C. fargesii leafed out late in the first set of shoots. Moreover, leaf number (except for L. chinense), individual leaf area, twig stem length (except for L. chinense) and diameter were significantly smaller in the second than in the first set of shoots for four species, indicating lower twig investment in the second shoots for all the sampled species. In general, leaf herbivory damage, rates of leaf emergence and expansion were not smaller (sometimes significantly greater), but the total investment on twigs was significantly lower in the second shoots compared to the first. We speculate that these differences might result from the selective force of heavy herbivory pressure and adverse climate conditions of coming winter for the leaves produced during the second set of shoots.

    Strategy of fine root expansion of Phyllostachys pubescens population into evergreen broadleaved forest
    LIU Jun, YANG Qing-Pei, SONG Qing-Ni, YU Ding-Kun, YANG Guang-Yao, QI Hong-Yan, and SHI Jian-Min
    Chin J Plan Ecolo. 2013, 37 (3):  230-238.  doi:10.3724/SP.J.1258.2013.00023
    Abstract ( 748 )   PDF (348KB) ( 1725 )   Save
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    Aims Roots, particularly fine roots, play an important role in interspecies competition. Our objective was to study the spatial distribution, morphological characteristics and growth rates of fine roots in both bamboo (Phyllostachys pubescens) and broad-leaved trees to better understand the mechanisms of expansion of bamboo into evergreen broad-leaved forest.
    Methods We continuously sampled P. pubescens forest (PPF), bamboo-broad-leaved mixed forest (BMF) and evergreen broad-leaved forest (EBF) perpendicular to a bamboo-broad-leaved forest interface on Dagang Mountain, Jiangxi Province, China. The live fine root biomass, specific root length (SRL), root length density (RLD), fine root growth and turnover rates were comparatively analyzed by soil core and ingrowth methods.
    Important findings Fine root biomass of PPF (1 201.60 g·m–2) was much larger than that of BMF (601.18 g·m–2) and EBF (204.88 g·m–2). Vertical stratification of bamboo fine roots in BMF was found to shift from lower to upper soil layers, SRL of bamboo significantly increased by 123.42% and average RLD of bamboo was 210.0% greater than that of broad-leaved trees. In addition, both growth and turnover rates of bamboo fine roots were faster than those of trees. Findings indicated that P. pubescens, with wide, precise, flexible and fast nutrient access and space-occupation abilities, would outcompete trees belowground, resulting in expansion of its population into evergreen broad-leaved forest.

    Seasonal dynamics of night-time stem water recharge of Schima superba and its relation to tree architecture and leaf biomass
    ZHAO Xiao-Wei, ZHAO Ping, ZHU Li-Wei, NI Guang-Yan, ZENG Xiao-Ping, and NIU Jun-Feng
    Chin J Plan Ecolo. 2013, 37 (3):  239-247.  doi:10.3724/SP.J.1258.2013.00024
    Abstract ( 927 )   PDF (648KB) ( 1246 )   Save
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    Aims Our objectives are to study the effects of tree architecture and leaf biomass of Schima superba on seasonal variations of nocturnal stem water recharge and to elucidate the compensation mechanism for hydraulic limitation and response to the hydraulic limitation hypothesis proposed by Roan and Yoder.
    Methods Night-time sap flow of 15 trees in a S. superba plantation was measured with Granier-type sensors installed in the sapwood at a height of 1.3 m for calculating night-time stem water recharge. Single and multiple linear regressions were performed in data analysis.
    Important findings The ending time of nocturnal sap flow was not followed by photosynthetically active radiation (PAR) but was the active time, which was unrelated to diameter at breast height (DBH). Night-time stem water recharge (W) was strongly linearly related with DBH, canopy size, sapwood area and leaf biomass (r = 0.596 to 0.895), except in winter. The linear relationship between W and tree height was found only in spring. W was positively affected by canopy in spring and summer, but by DBH in autumn and by tree height in winter. The results show that tree architecture and leaf biomass had significant effects on W and the degree changed with seasons.

    Effects of soil thickness on dry-season water relations and growth in Robinia pseudoacacia
    WANG Lin, FENG Jin-Xia, and WAN Xian-Chong
    Chin J Plan Ecolo. 2013, 37 (3):  248-255.  doi:10.3724/SP.J.1258.2013.00025
    Abstract ( 820 )   PDF (396KB) ( 1743 )   Save
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    Aims Our main purposes were to explore effects of soil thickness on the soil water carrying capacity of black locust (Robinia pseudoacacia) forests and to investigate the role of soil moisture in causing decline of black locust forests in regions of northern China in recent years.
    Methods We measured soil moisture, pre-dawn twig water potential and gas exchange of black locust in the dry season and wet season. We also measured stable carbon isotope ratio (δ13C) of leaf, leaf morphology and growth of black locust. Combined with the differential response in the dry season and wet season, we analyzed the relationship between water status of black locust and the soil thickness.
    Important findings In the dry season, the twig pre-dawn water potential and soil moisture significantly declined with decreased soil thickness, and the net photosynthetic rate and stomatal conductance of black locust also decreased. But there were no significant differences in these indexes in the wet season. Average soil moisture in the dry season was only 60% that in the wet season. With decrease in soil thickness, δ13C increased, area of leaf decreased and leaf mass per area increased. As a result, tree height and diameter at breast height significantly decreased with decrease in soil thickness. Results revealed that the water status of black locust in the different seasons strongly reflected water supply capacity of the soil, and that thin soil thickness was the main cause for the decline of black locust forests due to low carrying capacity of vegetation caused by inadequate water storage in the dry season.

    Effects of water and nitrogen supply on parameters of root and leaf senescence in cotton plants grown under root restriction and with under-mulch drip irrigation
    TAO Xian-Ping, LUO Hong-Hai, YANG Hai, DING Quan-Sheng, ZHANG Ya-Li, and ZHANG Wang-Feng
    Chin J Plan Ecolo. 2013, 37 (3):  256-267.  doi:10.3724/SP.J.1258.2013.00026
    Abstract ( 520 )   PDF (704KB) ( 1060 )   Save
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    Aim Our objective was to evaluate the influence of the water and nitrogen treatments on parameters of root and leaf senescence in cotton plants grown under root restriction and with under-mulch drip irrigation.
    Methods Our experimental materials were upland cotton cultivars ‘Xinluzao 13’ and ‘Xinluzao 33’, which are the main cultivars grown in the study region of northern Xinjiang, northwestern China. Treatments consisted of root restriction (RR), unrestricted root system (CK, control) and four levels of water and nitrogen supply: water
    and nitrogen deficiency (W0N0), water deficiency (W0N1), nitrogen deficiency (W1N0) and moderate supply of water and nitrogen (W1N1). The treatments were applied in a split-split plot design. Cotton plants were cultivated in soil columns to control the vertical depth of root growth and to regulate application of water and nitrogen. We measured the activity of antioxidant enzymes in the root and leaf and the accumulation and distribution of biomass at the yield-determining stages (from flowering to the full boll opening stage).
    Important findings The root biomass, activity of antioxidant enzymes (superoxide dismutase, guaiacol peroxidase and catalase) in the root and leaf, total plant biomass and the root/shoot ratio under root restriction decreased compared with the control. In contrast, aboveground biomass and cotton yield under root restriction were considerably higher than with the control. The supply of water and nitrogen effectively regulated root and leaf growth. With regard to their effects on antioxidant enzyme activity in the root and leaf, SPAD chlorophyll content, aboveground biomass and cotton yield, the water and nitrogen treatments were ranked as W1N1 > W0N1 > W1N0 > W0N0. In contrast and with regard to the shoot/root ratio and root biomass, the treatments were ranked as W0N0 > W1N0 > W0N1 > W1N1. Consequently, interaction between root restriction and the applied water and nitrogen regime had a marked effect on cotton growth and yield. Root restriction in conjunction with a moderate supply of water and nitrogen was the optimal treatment for aboveground biomass and cotton yield, whereas the root/shoot ratio was lowest in this treatment.

    Review
    Review of recent advances on the production and eco-physiological roles of green leaf volatiles
    SUN Hai-Feng, LI Zhen-Yu, WU Bin, and QIN Xue-Mei
    Chin J Plan Ecolo. 2013, 37 (3):  268-275.  doi:10.3724/SP.J.1258.2013.00027
    Abstract ( 922 )   PDF (292KB) ( 1929 )   Save
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    We review advances in understanding the production, eco-physiological roles, and related regulatory mechanism of green leaf volatiles (GLVs). GLVs are six-carbon aldehydes, alcohols and esters derived from the hydroperoxide lyase branch of the octadecanoic acid pathway in plants. Besides leaves, other tissues such as root, stem, fruit, and seed are also reported to be capable of producing the GLVs regulated at the levels of transcription and post-transcription in plants. GLVs composition and amounts are influenced by the developmental stage and growth environment such as seasonal change in a given plant. In addition, the formation of GLVs can be induced by biotic stress such as insect attack, inoculation of pathogenic bacteria and inhabitation of beneficial fungi, as well as abiotic ones such as nitrogen deficiency. Although GLVs are primarily recognized as important contributors to unique flavors, they also play important roles in direct and indirect defense responses. They not only inhibit the reproduction of bacteria, fungi and insects, but also induce the synthesis of various defensive compounds. They can also prime different signal induction pathways. The potential roles that GLVs played in the quality formation of Chinese herbs, especially genuine ones, are discussed based on their wide distribution and multi-layered defensive roles in plants. It is necessary and urgent to carry out related research on GLVs in Chinese herbs for their sustainable and green development.


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