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Table of Content
    Volume 38 Issue 11
    01 November 2014

    The natural landscape of wetland in the Napahai Plateau of Shangri-La, Yunnan, China. Cao et al. investigated the diversity and distributional patterns of soil fungi and correlations with soil factors under different levels of disturbance (Pages 1166–1173 of this issue) (Photographed by CHEN Guang-Lei).

      
    Research Articles
    Changes in soil respiration and its temperature sensitivity at different successional stages of evergreen broadleaved forests in mid-subtropical China
    FAN Yue-Xin, YANG Yu-Sheng, GUO Jian-Fen*, YANG Zhi-Jie, CHEN Guang-Shui, XIE Jin-Sheng, ZHONG Xiao-Jian, and XU Ling-Lin
    Chin J Plan Ecolo. 2014, 38 (11):  1155-1165.  doi:10.3724/SP.J.1258.2014.00111
    Abstract ( 599 )   PDF (1029KB) ( 1008 )   Save
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    Aims Studies on the influences of forest succession on soil respiration (Rs) and its temperature sensitivity (Q10) are controversial, leading to uncertainties in the accuracy of global carbon budget. Our objectives were to determine: (1) changes of Rs and Q10 in a succession series of mid-subtropical forests, (2) seasonal variations of Rs and its relationships with temperature and water content, and (3) the underlying mechanism of changes in Rs with succession.
    Methods We selected stands of an evergreen broadleaved forest at the early successional stage (15 years), middle successional stage (47 years), and late successional stage (110 years) under similar site conditions in Jian’ou, Fujian. Monthly Rs was measured by using an infrared gas exchange system from September 2009 through August 2010. Soil temperature and moisture were measured concurrently. The relationships of Rs with annual litterfall, fine root biomass, contents of soil organic carbon (SOC) and total nitrogen (TN) in the 0–20 cm soil layer were tested by linear regression analysis
    Important findings The average values of Rs were 2.38, 3.32 and 3.91 μmol·m–2·s–1, and the average values of Q10 were 2.64, 1.97 and 1.79, respectively, in the early, middle, and late successional stages. Compared to in the early successional stage, Rs was increased significantly by 64.29% while Q10 was decreased by 32.30% in the late successional stage. The seasonal patterns of Rs were similar among the three successional stages; soil temperature and water content explained 69.5%, 81.9% and 61.3% of the seasonal variations. According to regression analysis, soil respiration was positively correlated with annual litterfall, fine root biomass, and contents of SOC and TN in the 0–20 cm soil layer. Succession promoted carbon emission and reduced soil respiration sensitivity in our study, which might be related to the increases in fine root biomass, carbon input and soil nutrient with forest succession.

    Soil fungi distribution patterns under different levels of disturbance in the wetland of Napahai Plateau
    CAO Ping-Lin, LU Mei, TIAN Kun, Lü Si-Tong, YANG Hong-Sheng, YAO Xi, LI Li-Ping, and YUE Hai-Tao
    Chin J Plan Ecolo. 2014, 38 (11):  1166-1173.  doi:10.3724/SP.J.1258.2014.00112
    Abstract ( 510 )   PDF (559KB) ( 1066 )   Save
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    Aims The study was undertaken to reveal the effects of disturbance on carbon, nitrogen and soil fungi distribution patterns in Napahai wetland.
    Methods Changes in soil carbon and nitrogen and ecological characteristics of soil fungi were studied across wetlands of varying levels of disturbance, including primitive marsh (non-disturbance), swampy meadow (low disturbance), meadow (moderate disturbance), and cultivated wetland (high disturbance).
    Important findings (1) In both upper and lower soil layers, soil organic matter (SOM), total nitrogen (TN), C:N and pH significantly differed (p < 0.01) among the four wetland types; SOM and TN decreased with increasing level of disturbance. (2) Following the culture on PDA medium, the abundance of soil fungi was greater in the upper layer than in the lower layer within the same type of wetland soil; with increasing level of disturbance, the abundance of fungi gradually increased, and the abundance of fungi was negatively correlated with pH value, SOM and TN, and positively correlated with C:N (2-tail test, p < 0.05). (3) Phylogenetic analysis shows that the soil fungi in Napahai wetland occur as Ascomycota, Basidiomycota, and Zygomycota, with Ascomycota being the dominant type and playing a key role in decomposition of soil carbon and nitrogen in plateau wetland.

    Effects of vegetation restoration on content and spectroscopic characteristics of dissolved organic matter in eroded red soil
    LIU Zhu, YANG Yu-Sheng, SI You-Tao, KANG Gen-Li, and ZHENG Huai-Zhou
    Chin J Plan Ecolo. 2014, 38 (11):  1174-1183.  doi:10.3724/SP.J.1258.2014.00113
    Abstract ( 659 )   PDF (875KB) ( 1121 )   Save
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    Aims Dissolved organic matter (DOM) plays an important role in soil nutrient cycling. The chemical stability, capability of absorption on mineral soil surface and availability to microbes of DOM could be influenced by its composition and chemical structure. The objective of this study was to investigate the effects of vegetation restoration on content and spectroscopic characteristics of DOM in eroded red soil.
    Methods The study site is located in Changting, Fujian Province, in subtropical China. Soil samples in the depth of 0–60 cm from eroded red soil (ERS) and vegetation restoration (VR) sites were collected in July, 2013. Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) contents were determined and the spectroscopic characteristics of soil DOM were measured by means of ultraviolet (UV) absorbance, fluorescence (in emission and synchronous modes) and fourier-transform infrared (FTIR) spectroscopic techniques.
    Important findings The content of soil DOC in VR was significantly higher than in ERS. For soil layers from 0 to 60 cm at a 10 cm interval, content of DOC in VR was 5.6, 4.7, 4.6, 3.1, 2.4 and 2.2 times of that in ERS, respectively. The difference in DON content between VR and ERS varied inconsistently across soil layers. In all soil layers, the Special Ultraviolet-Visible Absorption (SUVA) of DOM from VR was significantly higher than that from ERS; HIXem (Humification Index, emission mode) of DOM from VR was slightly higher than that from ERS; while there was no apparent difference in HIXsyn (Humification Index, synchronous mode) of DOM between the two sites. In the synchronous fluorescence spectra of DOM, the main emission peaks arose from protein-like and aromatic-aliphatic fluorophores. FTIR spectra showed that there were more functional groups in DOM from VR, with higher absorption proportion of aromatic rings and carboxylates. The aromaticity and humification index of soil DOM decreased with increasing soil depth at both sites, which were positively related to total soil organic carbon and nitrogen. In conclusion, vegetation restoration significantly increased the content of soil DOC and the aromaticity index of DOM, and slightly increased the humification index of soil DOM, rendering soil DOM to be more complex and less susceptible to degradation in favor of soil fertility recovery.

    Spatial heterogeneity of vegetation under different grazing intensities in a Stipa breviflora desert steppe
    HUANG Chen, ZHANG Yu, WANG Jing, LI Yuan-Heng, WU Shi-Liu, TA Na, ZHAO Meng-Li, HAN Guo-Dong, LANG Bada-Lahu, and ZHAO Yan-Fang
    Chin J Plan Ecolo. 2014, 38 (11):  1184-1193.  doi:10.3724/SP.J.1258.2014.00114
    Abstract ( 484 )   PDF (938KB) ( 1079 )   Save
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    Aims Our objectives were to determine whether exponential function law is suitable to fit different levels of plant spatial heterogeneity in Stipa breviflora desert steppe, and to elucidate the patterns of species and community spatial heterogeneity under different grazing intensities, for better understanding the influence of grazing on plant community diversity, productivity and stability.
    Methods An experiment with randomized complete block design was conducted at the study site with four treatments and three replications for each treatment. The treatments consisted of light grazing, moderate grazing, heavy grazing and no grazing, respectively. Samples were taken from 50 cm × 50 cm quadrates (L quadrate) at every 0.5 m along three 50 m line transects, and totally 100 quadrates were measured. Each L quadrate was equally separated into four 25 cm × 25 cm smaller quadrates (S quadrate). All species appeared in the S quadrates were recorded at the peak growth period. The exponential function law was used to fit the data in different grazing treatments.
    Important findings Results showed that the species studied had good concordance with exponential function law under different grazing intensities. With increases in grazing intensity, based on the species occurrence frequency, plant community gradually shifted from a mixture of Stipa breviflora, Cleistogenes songorica, Artemisia frigida, Salsola collina to mixed Stipa breviflora and Cleistogenes songorica. The spatial heterogeneity was species-specific in different grazing treatments. With increasing grazing intensity, the plant species with increased spatial heterogeneity gradually reduced from Cleistogenes songorica, Arternisia frigida, Stipa breviflora, Convolvulus ammannii, Salsola collina, Allium mongolicum, Leymus chinesis, Chenopodium aristatum, and Haplophyllum dauricum to only Cleistogenes songorica and Stipa breviflora. The number of species with greater spatial heterogeneity than community spatial heterogeneity deceased from the control to the heavy grazing treatment.

    How a winter wildfire affect plant community in subalpine grassland of western Sichuan, China?
    WANG Xie, XIANG Cheng-Hua, LI Xian-Wei, and WEN Dong-Ju
    Chin J Plan Ecolo. 2014, 38 (11):  1194-1204.  doi:10.3724/SP.J.1258.2014.00115
    Abstract ( 585 )   PDF (619KB) ( 946 )   Save
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    Aims It had been reported that there are relationships among soil physiochemical properties, soil microbial characteristics, and plant community structures. However, there is still a dispute about the best path of shaping plant community structure by fire. To assist with sustainably managing grassland ecosystem, a hypothesis was put forward on shaping of the plant community structure by winter wildfire in a subalpine grassland of western Sichuan, in which the effects of fire on soil environment (soil physiochemical properties and soil microbial characteristics) could explain the changes of post-fire plant community structure and diversity.
    Methods To test the abovementioned hypothesis, variables of soil physiochemical properties, soil microbial properties, and plant community structure in naturally burned and unburned areas at different locations were studied. For determination of the direct and indirect effects of fire on plant community structure and diversity, we simulated five paths that fire shapes the plant community structure and diversity by using structural equation modelling according to the result of non-metric multidimensional scaling analysis.
    Important findings The winter fire had little direct effects on plant community. The best-fit value was given by the path model in which winter fire changed soil microbial properties, which in turn affected plant community structure directly or indirectly by modifying soil physiochemical properties. The results suggested that the effects of the low-intensity fire on soil physiochemical properties and plant community structure may be achieved through mortality and reproduction of soil microbes. However, as the soil is a whole environment, it needs to be studied further to explore the roles of microbial activities in regulating soil biochemical cycle after fire, especially the nitrogen cycle.

    Microclimate characteristics in shelterbelt of tea garden in coastal hilly region of eastern Shandong, China
    YANG Fei, YANG Ji-Hua, AI Zhao, ZHANG Guo-Qing, and HU Jian-Peng
    Chin J Plan Ecolo. 2014, 38 (11):  1205-1213.  doi:10.3724/SP.J.1258.2014.00116
    Abstract ( 483 )   PDF (587KB) ( 798 )   Save
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    Aims Over a year, Rushan tea is booming gradually, but due to the low temperature in winter and early spring, the areas for tea plantation has been decreasing year by year. Therefore, how to achieve a higher yield at lower cost has become a major issue in the test plantation area. The paper examined the characteristics of microclimate in four shelterbelt systems of tea garden in order to identify a suitable forest-tea system in the study area.
    Methods The tea plantation studied was established in the spring of 2007 with terrace soil preparations, involving four forest shelterbelt grid systems (i.e. 8 m × 80 m, 12 m × 80 m, 20 m × 80 m and 40 m × 80 m). The wind speed, air temperature, soil temperature, relative air humidity and relative soil moisture were measured in the four shelterbelt systems in April, August and December of 2013, with the tea plantation without shelterbelt as control.
    Important findings Firstly, the four shelterbelt systems all reduced wind speed effectively, increased air relative humidity, regulated air temperature, soil temperature and soil relative moisture, and improved ecological environment in favor of tea production. Secondly, due to the seasonal variations of regional water flux and solar radiation, the regulation effects of the four shelterbelt systems differed. Thirdly, the results of principal component analysis showed that, the main factors inducing different microclimate characteristics were the air temperature and soil temperature, with factor loads of –0.978 and 0.986, respectively. The wind speed and air temperature showed a highly significant correlation, but there was no significant linear relationship between wind speed and soil temperature, indicating that wind speed could affect the microclimate indirectly. Overall, the shelterbelt system of 8 m × 80 m is better than the other three systems in the effects of regulating microclimate.

    Dynamics of water usage in Haloxylon ammodendron in the southern edge of the Gurbantünggüt Desert
    DAI Yue, ZHENG Xin-Jun, TANG Li-Song, and LI Yan
    Chin J Plan Ecolo. 2014, 38 (11):  1214-1225.  doi:10.3724/SP.J.1258.2014.00117
    Abstract ( 455 )   PDF (982KB) ( 1249 )   Save
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    Aims Plant water use is an important aspect of plant-water relations in desert regions, and is vital in understanding the adaptation of desert species to arid environment. Haloxylon ammodendron is a dominant plant species in the Gurbantünggüt Desert, China. Its water use pattern has an important effect on water balance of the local ecosystem and plant community composition. This study aims to investigate the dynamics of water usage in H. ammodendron and its response to soil water fluctuations resulting from precipitation pulses.
    Methods Oxygen stable isotope ratios (δ18O) were measured for xylem water, soil water in different soil layers (0–300 cm depth), precipitation and groundwater. Four potential water sources were classified: shallow (0–40 cm), middle (40–100 cm) and deep soil water (100–300 cm), and groundwater. The possible ranges of potential water sources used by H. ammodendron were calculated using the IsoSource model.
    Important findings Main water sources for H. ammodendron shifted from the shallow soil water in April to the groundwater during May to September. In April, the contributions of shallow soil water were in the range of 62%–95%, and the possible ranges of middle and deep soil water and groundwater were 0–8%, 0–15% and 0–38%, respectively. However, during May to September, the contribution of shallow soil water decreased drastically while that of groundwater increased rapidly. Contributions of groundwater were in the range of 68%–100%. Haloxylon ammodendron responded differently to two similar precipitation pulses occurred in different months. After the 6.7 mm precipitation pulse on May 22, the usage of soil water increased from 9.8% prior to the event to maximum at 40.4% one day after rainfall (May 23), while the usage of groundwater decreased from 83%–98% to 42%–81%. After 7 mm precipitation pulse on August 31, the usage of soil water was almost unchanged and the usage of groundwater was still up to 71%–98%, implying that roots of H. ammodendron in the upper soil layer are inactive due to the long-lasting low soil water content. Hence, H. ammodendron seemed to be insensitive to the August precipitation pulse. The shallow soil water recharged by snowmelt and precipitation in spring and groundwater are two important water sources for H. ammodendron. Dynamics of water usage in H. ammodendron reflects its adaptation to this water-limiting desert environment.

    Water sources of Medicago sativa grown in different slope positions in Yanchi County of Ningxia
    ZHU Lin, QI Ya-Shu, and XU Xing
    Chin J Plan Ecolo. 2014, 38 (11):  1226-1240.  doi:10.3724/SP.J.1258.2014.00118
    Abstract ( 508 )   PDF (1056KB) ( 1120 )   Save
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    Aims Alfalfa (Medicago sativa) is considered as an elite forage with high economic and ecological values. In semi-arid areas of Northwest China, the low rainfall is far from satisfying water demand of alfalfa. The northern part of Yanchi County is adjacent to Mu Us desert and has a shallow groundwater table. In this area, groundwater could be the potential water sources for growing alfalfa. Our objective was to investigate the growth performance and potential water sources of alfalfa grown in four slope positions with different altitudes in the bottomland of northern Yanchi County.
    Method Stable 18O and D isotope compositions (δ18O and δD) of different water sources and xylem water were analyzed in April, June, July and August 2013. IsoSource was used to calculate the probable contribution of different water sources to the total plant water uptake. Stomatal conductance, carbon isotope discrimination (Δ13C) of whole plant, soil volumetric water content in the 0–300 cm soil profile were also determined.
    Important findings Slope position had a significant effect on water content in the 0–300 cm soil profile. Highest soil water content was found in the slope position of lowest altitude. The δ18O-δD coordinates of soil water and plant stem xylem water were distributed on the right of Northwest China local meteoric water line (LMWL), indicating that oxygen and hydrogen isotopic compositions in the water sources of alfalfa were subjected to enrichment due to evaporation. The δ18O values of soil water in the 0–450 cm profile increased with altitude. Soil water δ18O values decreased with the depth of soil profile for a given slope position. Soil water δ18O values in deep profile were similar to those in groundwater, implying that groundwater would move to the upper soil layer via soil capillary. Seasonal fluctuation was observed in soil water δ18O in the 0–40 cm profile, while soil water δ18O in profile below 270 cm was stable seasonally. Plant stem xylem water δ18O value was significantly lower (p < 0.001) in the slope position 1 than in other three slope positions in April, July and August. Highest water utilization rate from deep soil profile (below 270 cm) was recorded for alfalfa grown in the slope position 1 in April, June and July. In August, alfalfa grown in the slope positions 1, 3 and 4 mainly used soil water in the 150–270 cm and 270–450 cm profiles and groundwater; highest dependence on soil water in the shallow profile (0–20 cm) was found in alfalfa grown in the slope position 2. Higher yield, whole plant Δ13C value and stomatal conductance were observed in alfalfa grown in the slope position 1 than in other three slope positions. These results suggest that bottomland with lower altitude and shallow groundwater table should be adopted when planting alfalfa without irrigation in the semi-arid areas of Northwest China where average annual rainfall is around 280 mm. Thus, groundwater could contribute to better growth performance of alfalfa, leading to higher ecological and economic returns.

    A mechanistic model of light-response of photosynthetic electron flow and its application
    YE Zi-Piao, HU Wen-Hai, XIAO Yi-An, FAN Da-Yong, YIN Jian-Hua, DUAN Shi-Hua, YAN Xiao-Hong, HE Li, and ZHANG Si-Si
    Chin J Plan Ecolo. 2014, 38 (11):  1241-1249.  doi:10.3724/SP.J.1258.2014.00119
    Abstract ( 455 )   PDF (603KB) ( 951 )   Save
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    Aims Our objectives were to introduce a mechanistic model of light-response of photosynthetic electron flow and to understand how the photosynthetic electron flow respond to light intensity and the characteristics of light-harvesting pigment molecules.
    Methods Light-responses of photosynthetic electron flow were measured in Lagedium sibiricum, Erigeron annuus and Aster tataricus by using a LI-6400-40B, and the curves were fitted by a mechanistic model of light-response of photosynthetic electron flow.
    Important findings (1) The mechanistic model of light-response of photosynthetic electron flow not only well described the light-response curves of photosynthetic electron flow in L. sibiricum, E. annuus and A. tataricus, but also obtained some key photosynthetic parameters, e.g. maximum photosynthetic electron flow, saturation irradiance and initial slope of the light-response curve; the fitted photosynthetic parameters were similar to the measured values. (2) The effective light absorption cross-section of light-harvesting pigment molecules quickly decreased with increasing irradiance in L. sibiricum, and showed slowest rate of decrease in E. annuus. (3) The light-harvesting pigment molecules in the lowest excited state increased most rapidly with increasing irradiance in L. sibiricum, and most slowly in E. annuus. In conclusion, compelling evidence indicates that decrease in effective absorption cross-section and increase in the number of light-harvesting pigments in the lowest excited state would reduce light energy absorption.

    Review
    Application and progress of split-compartment facility in studies of arbuscular mycorrhizal fungi
    WANG Qiang, WANG Qian, DONG Mei, WANG Xiao-Juan, ZHANG Liang, and JIN Liang
    Chin J Plan Ecolo. 2014, 38 (11):  1250-1260.  doi:10.3724/SP.J.1258.2014.00120
    Abstract ( 511 )   PDF (728KB) ( 1068 )   Save
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    Arbuscular mycorrhizae (AM) are an important symbiosis between vascular plants and AM fungi in terrestrial ecosystems. Many studies have focused on their species diversity, distribution, and functions in natural habitats. However, AM fungi cannot be propagated in isolation; they need to be cultured with host plants. Thus, development of the culture method has been a hotspot in the AM research. In order to facilitate the advancement of research on AM fungi, we reviewed all the culture methods for AM fungi and their applications. Seven split-compartment cultivation systems were systematically discussed, including glass bead split-compartment culture system, two-compartment H-bridge cultivation system, root exclusion compartment culture system, in vitro mycorrhizal donor plants (MDP) culture system, dual axenic culture system, dual monoaxenic culture system of AM fungi with Ri T-DNA transformed root, and the improved split-compartment monoaxenic culture system of AM fungi with Ri T-DNA transformed root. Glass bead split-compartment culture system plays an irreplaceable role in easily separating AM fungi from the medium, hence obtaining a large quantity of axenic AM fungal propagules, which can be used for studying the absorption of mineral nutrients and trace elements. The H-shaped compartment cultivation system and root exclusion compartment culture system (RECs) can be used for obtaining continuous common mycorrhizal networks (CMNs), making it possible for the study of secondary metabolites information exchange, such as the plant-plant and plant-insect allelopathy. In vitro mycorrhizal donor plants (MDP) culture system has the advantage to study the biological effects of AM fungi on monoculture of host plants or mixed cultivation with different plant species. The dual axenic culture system facilitates the study of the infection process of AM fungi and their physiological and biochemical properties, and assists with gaining theoretical understanding on pure culture of AM fungi. Dual monoaxenic culture system of AM fungi with Ri T-DNA transformed root could be used to obtain axenic mycelium of AM fungi, and for further study of its genetic, physiological and biochemical properties. Based on dual monoaxenic culture system of AM fungi with Ri T-DNA transformed root, the medium can be replaced in the hyphal compartment and carbon source could be supplemented in the mycorrhizal compartment, and thus AM fungal propagules could be harvested continuously. The improved split-compartment monoaxenic culture system of AM fungi with Ri T-DNA transformed root is an effective method to improve the production of the inoculants with AM fungi. In a word, the different split-compartment instruments have provided effective methods for mycorrhizal research in autecology, population ecology and community ecology.


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