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Table of Content
    Volume 37 Issue 11
    01 November 2013

    The landscape of Pinus kesiya var. langbianensis primary forest in Jinggu County, Yunnan Province, China. The primary forests are widespread in west of the west slope of Ailao Mountain of the province. The specie has rapid growth, shooting two times per year, and strong ecological adaptability, being of importance in afforestation and resin tapping in the province. Li et al. investigated the phenotypic variation of cones and seeds in natural populations of the specie

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    Research Articles
    Relationships between species diversity and C, N and P ecological stoichiometry in plant communities of sub-alpine meadow
    CHEN Jun-Qiang, ZHANG Rui, HOU Yao-Chen, MA Li-Na, DING Lu-Ming, LONG Rui-Jun, and SHANG Zhan-Huan
    Chin J Plan Ecolo. 2013, 37 (11):  979-987.  doi:10.3724/SP.J.1258.2013.00101
    Abstract ( 851 )   PDF (489KB) ( 1844 )   Save
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    Aims Our objective was to investigate relationships between species diversity of pasture and C, N and P stoichiometry characteristics of plants at the community level.
    Methods This field survey focused on plant nutrient stoichiometry of two-level yields in alpine meadow in Eastern Qilian Mountain, China was conducted in early August 2012. Two survey sites were identified as high-yield grassland and low-yield grassland. At each survey site, two 8 m × 8 m plots were selected and divided into 64 1 m × 1 m subplots. For each subplot, the number of species was counted, and newly matured leaves were randomly selected after collecting the aboveground parts by clipping the plant at the soil surface. The collected leaves were sun-dried in the field and oven-dried at 80 °C to constant weight. All samples were finely ground and passed through a 40-mesh screen. Plant C concentration was analyzed by ash determination, plant N concentration was tested by Kjeldahl acid-digestion method and plant P concentration was analyzed by phosphorus vanadium molybdate yellow colorimetric method. Pearson’s bivariate correlation was used to test the relationship between plant C, N, and P stoichiometric traits and number of species. Two-tailed Student’s t-tests were used to compare plant stoichiometric variables.
    Important findings Mean values of plant C, N and P concentrations in high-yield grassland were 53.05%, 1.99%, and 0.22%, respectively, and those in low-yield grassland were 52.51%, 2.28% and 0.19%, respectively. In high-yield grassland, the number of species was significantly positively correlated with plant N concentration and N:P ratio, while significantly negatively correlated with plant C:N ratio. In low-yield grassland, the number of species was significantly negatively correlated with N and P concentrations, but significantly positively correlated with C:N and C:P. Results indicated that the species of high-yield grassland were primarily limited by N concentration and positively correlated with N concentration. However, the species of low-yield grassland was co-limited by N and P concentrations and negatively correlated with N and P concentrations, thus indicating heterogeneity in C, N and P stoichiometry characteristics between high- and low-yield grasslands.

    Soil C mineralization and temperature sensitivity in alpine grasslands of the Qinghai-Xizang Plateau
    XU Li, YU Shu-Xia, HE Nian-Peng, WEN Xue-Fa, SHI Pei-Li, ZHANG Yang-Jian, DAI Jing-Zhong, WANG Ruo-Meng
    Chin J Plan Ecolo. 2013, 37 (11):  988-997.  doi:10.3724/SP.J.1258.2013.00102
    Abstract ( 488 )   PDF (925KB) ( 1400 )   Save
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    Aims Currently, the temperature sensitivity of soil carbon (C) mineralization and the factors that control it are the focus of studies on soil C cycle and global climate change. The main objectives of this study were to: (1) investigate the effects of temperature and land-use (fenced grassland vs. grazing grassland) on soil C mineralization and its temperature sensitivity (Q10) in the grasslands of Qinghai-Xizang Plateau and (2) determine the relationships of the rate of soil C mineralization with soil properties (e.g. soil organic carbon content (SOC), soil total nitrogen content (STN)).
    Methods Eleven pairs of plots (fenced sites vs. grazing sites) were selected along an east–west transect in northwest of Qinghai-Xizang Plateau. Soil samples were collected at a depth of 0–20 cm, to measure soil C mineralization rates under a temperature gradient (i.e. 5, 10, 15, 20, and 25 °C) in laboratory. Data for soil C mineralization rate on the 7th day and 56th day, respectively, were used to assess the short- and long-term effects.
    Important findings Soil C mineralization rates declined from east to west on fenced sites, but varied slightly on the grazing sites. Soil C mineralization rates increased significantly with increasing incubation temperature, and were strongly related to SOC and STN; higher the SOC and STN, greater the accumulative soil C mineralization. Q10 showed no apparent spatial pattern along the east–west transect, and was not susceptible to land-use with average Q10 values of 1.83 and 1.86 on the fenced sites and the grazing sites, respectively. Moreover, Q10 was not correlated with either SOC or STN. Findings in this study provide new insights on the responses of soil C mineralization and its temperature sensitivity to land-use change on the Qinghai-Xizang Plateau, contributing important information for evaluating soil C sequestration and its response to warming scenarios in this region.

    Phenotypic variations in cones and seeds of natural Pinus kesiya var. langbianensis populations in Yunnan Province, China
    LI Shuai-Feng, SU Jian-Rong, LIU Wan-De, LANG Xue-Dong, ZHANG Zhi-Jun, SU Lei, JIA Cheng-Xin-Zhuo, and YANG Hua-Jing
    Chin J Plan Ecolo. 2013, 37 (11):  998-1009.  doi:10.3724/SP.J.1258.2013.00103
    Abstract ( 698 )   PDF (574KB) ( 1285 )   Save
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    Aims Our objectives were to determine phenotypic variations in 11 natural Pinus kesiya var. langbianensis populations and their relationship with distributions.
    Methods We investigated 16 phenotypic traits for 330 individuals in 11 natural populations of P. kesiya var. langbianensis in Yunnan Province, and used nested analysis, variation coefficient, correlation analysis, and un-weighted pair-group method using arithmetic averages (UPGMA) cluster analysis to analyze results.
    Important findings There are significant differences in phenotypic variation among and within populations. Variation is greater within populations (54.76%) than among populations (10.44%). Mean phenotypic differentiation coefficient is 11.95% among populations. Differentiations among populations are relatively small. The average variation coefficient of seed weight is highest (35.51%), followed by cone weight (35.1%); the average variation coefficient of seed size is smallest (8.86%). The seed size is the most stable phenotypic traits. Phenotypic diversity is greatest in Jinggu County and smallest in Jinghong City. There are significant or highly significant correlations among most phenotypic traits in cones and seed, indicating that greater the cone length and cone weight, larger the seed scales, seed size, seed wing, 1 000 seeds weight, and the number of seed scales and seeds per cone. The mean annual temperature appears to be the most prominent ecological factor influencing phenotypic traits, followed by the January mean temperature and growing degree days at >5 °C. According to UPGMA cluster analysis, the 11 populations can be divided into two groups and four subgroups due to difference in geographic distance, which is significantly related to annual precipitation and growing degree days at >5 °C.

    Effects of maize-peanut intercropping and phosphate fertilizer on photosynthetic characteristics and yield of intercropped peanut plants
    JIAO Nian-Yuan, YANG Meng-Ke, NING Tang-Yuan, YIN Fei, XU Guo-Wei, FU Guo-Zhan, and LI You-Jun
    Chin J Plan Ecolo. 2013, 37 (11):  1010-1017.  doi:10.3724/SP.J.1258.2013.00104
    Abstract ( 704 )   PDF (426KB) ( 1533 )   Save
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    Aims Our objective was to determine the enhanced utilization of weak light in intercropped peanut plants (Arachis hypogaea) and the regulatory effects of phosphate (P) fertilizer in maize-peanut intercropping system, which is of great significance to elucidate photosynthetic adaptation mechanism of intercropped peanut plants and to increase the yield.
    Methods Chlorophyll (Chl) content and composition, photosynthetic light response curves, photosynthetic CO2 response curves, and fluorescence parameters in the functional leaves of intercropped peanut plants were studied at the experimental farm of Henan University of Science and Technology in 2011 and 2012.
    Important findings The Chl b content was higher, and the Chl a/b ratio was lower, in the functional leaves of intercropped peanut plants than in those of single cropped peanut plants with or without P fertilizer application. There were higher values of maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSII), photochemical quenching coefficient (qP) of photosystem II, apparent quantum yield (AQY), and photosynthetic rate, but lower values of stomatal conductance, RuBP carboxylation rate (Vcmax), electron transport rate (Jmax), and triose-phosphate utilization rate (TPU) in the functional leaves of intercropped peanut plants than in those of single cropped peanut plants. Application of P fertilizer was beneficial to improving chlorophyll content, ΦPSII and qP of photosystem II, Vcmax, Jmax, and TPU in the functional leaves of intercropped peanut plants. It suggested that intercropped peanut plants could make more efficient use of weak light because of the higher Fv/Fm, ΦPSII and qP of photosystem II resulting from higher Chl b content and changes chlorophyll composition of functional leaves, which strengthened the capacity of light absorption and transformation, but not because of the higher CO2 rate of fixation and improved carboxylation efficiency. Application of P fertilizer was beneficial to improving the utilization of weak light and to increasing the yield of intercropped peanut, resulting in an increase in the land equivalent ratio of the maize-peanut intercropping system by 6.2%–9.3%.

    Genotypic differences in salt tolerance from germination to seedling stage in peanut
    CI Dun-Wei, DAI Liang-Xiang, SONG Wen-Wu, and ZHANG Zhi-Meng
    Chin J Plan Ecolo. 2013, 37 (11):  1018-1027.  doi:10.3724/SP.J.1258.2013.00105
    Abstract ( 675 )   PDF (289KB) ( 1031 )   Save
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    Aims In the present study, the degree of salt tolerance in different peanut varieties/lines was investigated from emergence to seedling stage.
    Methods The seeds of peanut varieties/lines were planted in pots with salt levels of 0, 0.15%, 0.30%, and 0.45% NaCl in soils. The degree of salinity tolerance was systematically evaluated according to ten indices reflecting emergence, morphology, and biomass accumulation, etc.
    Important findings Statistic analysis for the 10 indices, including the relative emergence time, relative plant height, relative stem height, relative taproot length, relative shoot fresh mass, relative root fresh mass, relative shoot dry mass, relative root dry mass, and relative plant dry mass, showed large variations among the 107 varieties/lines; each index displayed a normal distribution under different salt stresses. Using the principal component analysis, the ten indices could be categorized into several independent factors. According to the total score, the 107 varieties/lines were divided into four groups, i.e., highly salt tolerant, salt tolerant, salt susceptible, and highly salt susceptible, by cluster analysis at salt level of 0.15%, 0.30%, and 0.45%, respectively. The 107 varieties/lines accounted for 29.0%, 39.0%, 27.5%, and 4.5%, respectively under salt level of 0.15%, and 5.5%, 34.5%, 23.5%, and 29.0%, respectively under salt level of 0.30%, in the highly salt tolerant, salt tolerant, salt susceptible, and highly salt susceptible groups. The salt tolerance in some varieties/lines varied with the level of salt stresses; some varieties/lines showed tolerance under low salt stress but susceptible under high salt stress. The number of varieties/lines showed the same tolerance or susceptibility under different salt stresses was 1 (‘Fuhua 11’), 7 (‘Huayu 28’, ‘Z11’, ‘Huayu 39’, ‘Huayu 32’, ‘HLN2’, ‘Yueyou 26’, and ‘XE019’), 0 and 1 (‘D1035’), respectively, in the highly salt tolerant, salt tolerant, salt susceptible, and highly salt susceptible groups. The 10 indices reflecting emergence, morphology, and biomass accumulation, etc., differed significantly or highly significantly among he varieties/lines in the four groups. Compared to the salt tolerant groups, the salt susceptible groups had prolonged emergence time and increased inhibition in plant morphological development and biomass accumulation under high level of salt stress.

    Effects of arbuscular mycorrhizal fungi on calorific value and contents of carbon and ash in Robinia pseudoacacia
    ZHU Xiao-Qin, WANG Chun-Yan, SHENG Min, CHEN Hui, and TANG Ming
    Chin J Plan Ecolo. 2013, 37 (11):  1028-1034.  doi:10.3724/SP.J.1258.2013.00106
    Abstract ( 492 )   PDF (264KB) ( 1226 )   Save
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    Aims It is still unknown whether arbuscular mycorrhizal (AM) fungi could increase calorific value and carbon content in plants. Our objectives in this study were to (1) determine the effects of two AM fungi, Glomus intraradices and G. versiforme, on biomass, calorific value, carbon content, and ash content in black locust (Robinia pseudoacacia) seedlings; and (2) assess the effectiveness of G. intraradices and G. versiforme in affecting biomass and energy accumulation in black locust.
    Methods Three treatments were performed: black locust seedlings, including inoculations of seedlings with G. intraradices, G. versiforme, respectively, and no inoculum as control. Seedlings were grown in a greenhouse for 14 months following treatments, and then their biomass, gross calorific value, carbon content, and ash content of the roots, stems, and leaves were measured. Ash-free calorific value, energy accumulation, and carbon accumulation were calculated.
    Important findings We found that inoculations with the two AM fungi increased the biomass, calorific value, and carbon content in black locust seedlings. The accumulations of biomass, energy, and carbon were 89.61%, 102.20%, and 93.30% greater in black locust seedlings inoculated with G. intraradices, and 91.34%, 94.19% and 77.21% greater in those inoculated with G. versiforme, respectively, than the controls. Both calorific value and carbon content were the highest in seedlings inoculated with G. intraradices; and the gross calorific value of roots, stems and leaves were 7.72%, 8.94%, 8.41% higher, respectively, in seedlings inoculated with G. intraradices than the controls. Glomus intraradices was found to be more effective than G. versiforme in enhancing calorific value and accumulation of energy and carbon.

    Review
    Relationship between mycorrhizal fungi and functional traits in absorption roots: research progress and synthesis
    MIAO Yuan, WU Hui-Fang, MA Cheng-En, and KONG De-Liang
    Chin J Plan Ecolo. 2013, 37 (11):  1035-1042.  doi:10.3724/SP.J.1258.2013.00107
    Abstract ( 780 )   PDF (329KB) ( 1833 )   Save
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    Absorption roots usually refer to several terminal branch orders in a root branch that are comprised of primary tissues and are responsible for resource uptake. Functional traits of absorption roots have been widely used to assess and predict a range of functions and processes from individual to ecosystem scale. Mycorrhizal fungi colonization is one of the key traits exerting significant influence on root morphology, structure, and the inter-relationships among root traits. In this paper, we first review the relationships of mycorrhizal fungi with two traits closely related to resource uptake: root hair and root diameter; a hypothesis is proposed to describe relationships among mycorrhizal fungi, root hair and chemical defense. Then, we review how functional traits in different absorption roots are altered by mycorrhizal fungi adapting to environments differing in precipitation, temperature, soil fertility, and energy consumption. Finally, we identify several topics and research outlooks for guiding future studies to facilitate studies on the relationship between mycorrhizal fungi and root functional traits.

    Advances in the carbon use efficiency of forest
    ZHU Wan-Ze
    Chin J Plan Ecolo. 2013, 37 (11):  1043-1058.  doi:10.3724/SP.J.1258.2013.00108
    Abstract ( 686 )   PDF (427KB) ( 1582 )   Save
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    Carbon use efficiency (CUE), which is defined as the ratio of net carbon gain to gross carbon assimilation, can be used to assess not only the capacity of forests to transfer carbon from the atmosphere to the terrestrial biomass but also to determine the impact of respiration on productivity in forests. CUE is an important parameter for comparing carbon cycle variability among ecosystems. Understanding such controls on CUE can be helpful in determining whether the terrestrial ecosystem is a carbon source or sink. Forest CUE under different environmental regimes and global change scenarios has recently received increasing attention. This paper introduces the calculation methods of plant CUE and the corresponding measurement techniques, and reviews the research progress in the effects of important factors on forest CUE. The main findings are as follows: (1) Some studies proposed that CUE is constant among forests with a possible appropriate universal value of 0.50. However, it is doubtful whether this conservative CUE assumption regardless of ecosystem types is globally applicable. CUE can vary with ecosystems, forest types, species, and ontogeny of plant development. Forest ecosystems have a lower CUE than shrub and herbaceous ecosystems. CUE is significantly higher in deciduous than in mixed and evergreen forests. Tropical forests often have lower CUE than temperate forests. CUE is known to depend on successional stage and stand age. (2) Forest CUE is related to temperature, precipitation, and geographical factors. A parabolic relationship between CUE and annual mean temperature is founded at a global scale. Acclimation of the respiration to temperature contributes to high carbon-use efficiency in seasonally dry vegetation. The CUE decreases with enhanced precipitation and remains unchanged in areas where water availability is in surplus. CUE of plants grown at low light level is low. (3) The elevated CO2 may increase whole- plant respiration, causing CUE to decline. The potential for elevated CO2 to affect CUE may depend on tree age or genotype. (4) Plants grown on the barren soil, and under low temperature and drought conditions, may have larger changes in CUE than plants grown under near-optimal conditions. Forest managements such as irrigation, fertilization, and selective logging can affect ecosystem CUE. (5) CUE varies widely with the changing seasons within a year. The maximum of CUE in temperate forests usually occurs in spring. The future research should be focused on: (1) exploring the spatial variations in forest CUE and their driving mechanism from tissues, individual plant, community, to ecosystem scales; (2) analyzing the processes and mechanism in CUE of different vegetation types at temporal scales by combining the plant eco-physiology and biology with eddy covariance technique and modeling approaches; and (3) evaluating the response and adaption of forest CUE to climate change by synergistic experiments of multi-factors.

    Review on detection of critical transition in ecosystems
    SUN Yun, YU De-Yong, LIU Yu-Peng, and HAO Rui-Fang
    Chin J Plan Ecolo. 2013, 37 (11):  1059-1070.  doi:10.3724/SP.J.1258.2013.00109
    Abstract ( 780 )   PDF (441KB) ( 1812 )   Save
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    Ecosystem with alternative stable states would respond abruptly to minor changes in the external conditions and switch into an alternative stable state with different ecosystem structures and functions when the system approaches the transition threshold. This phenomenon is called critical transition. It is often the case that such transition can result in marked changes in ecosystem services, which are much likely to impact the sustainable development of human being. It is difficult to predict the critical transitions in ecosystems, but the large amount of research in this field show that by monitoring some generic properties (i.e. early-warning signals) relating to ecosystem status, we are able to discern if the system approaches the transition threshold; this can be used to predict the critical transitions in ecosystems. This paper summarizes the major findings and achievements in the field of detecting critical transitions in ecosystems. It first discusses the mechanism and consequence of critical transitions, and then introduces the basic theory behind the early-warning signals. We sum up the methods used to extract early-warning signals both from temporal and spatial dimensions. Finally, challenges confronting the contemporary research are summarized. In future, the application of early-warning signals should make full use of both temporal and spatial data and combine different indicators to improve our ability to forecast unfavorable environmental events. Also, special attention needs to be paid to the relationship between critical transitions and ecosystem structures so that we can strengthen the ability to predict critical transitions in ecosystems.


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