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Table of Content
    Volume 35 Issue 7
    01 July 2011

    Abies faxoniana forest at a treeline site in Wolong National Natural Reserve, western Sichuan of China. Li et al. investigated the relationships between tree-ring chronologies of A. faxoniana and climate conditions using different detrending methods (Pages 707–721 of this issue). (Photographed by LIU Guo-Hua)

      
    Research Articles
    Within-leaf allometric relationships of mature forests in different bioclimatic zones vary with plant functional types
    ZHU Jie-Dong, MENG Ting-Ting, NI Jian, SU Hong-Xin, XIE Zong-Qiang, ZHANG Shou-Ren, ZHENG Yuan-Run and XIAO Chun-Wang
    Chin J Plan Ecolo. 2011, 35 (7):  687-698.  doi:10.3724/SP.J.1258.2011.00687
    Abstract ( 2268 )   PDF (1027KB) ( 1767 )   Save
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    Aims Our objectives are to determine allometric relationships between petiole mass and lamina mass, area, and volume in different bioclimatic zones and to detect the effect of plant functional types on the relationships.
    Methods Typical and zonal mature forests were selected from boreal Huzhong, temperate Changbai Mountain, warm-temperate Dongling Mountain, subtropical Gutian Mountain, Shennongjia and Dujiangyan in China, and one 1 hm2 plot was investigated at each site. Traits of lamina and petiole of the dominant woody species were measured in August 2009. The relationship between lamina and lamina support was analyzed by the Standardized Major Axis estimation (model type II regression) with software (S)MATR Version 2.0.
    Important findings Statistically significant allometric scaling relationships were found between petiole mass and lamina mass, area, and volume in all functional types and climate zones, with common slopes of 0.82, 0.70 and 0.80, respectively, all of which significantly departed from 1.0. Shrubs had greater lamina volume at a given petiole mass than trees, but the lamina mass and area they support were not significantly different. Evergreen species were observed to have greater lamina mass and lamina volume than deciduous ones, whereas deciduous species had a greater lamina area at a given petiole mass than evergreen ones. With the exception of Shennongjia, the species in subtropical sites were found to have greater lamina mass, lamina area, and lamina volume than temperate sites at a given petiole mass. However, the petiolar support efficiency in the subtropical climate of Shennongjia was close to sites in temperate climate. Our results indicate that the petiole constrains the maximization of lamina size (including mass, area and volume) and that the allometric relationship between lamina and lamina support varies with plant functional type, climate and habitat.

    Effect of incubation starting time on litter decomposition rate in a subtropical forest in China
    LI Rong-Hua, DENG Qi, ZHOU Guo-Yi, and ZHANG De-Qiang
    Chin J Plan Ecolo. 2011, 35 (7):  699-706.  doi:10.3724/SP.J.1258.2011.00699
    Abstract ( 1838 )   PDF (491KB) ( 1556 )   Save
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    Aims Estimation of ecosystem carbon balance may be affected by timing of sampling. Our objective was to determine the effect of different incubation starting times on litter decomposition rate (k) in a tropical and subtropical forest.
    Methods We used litter bags and incubated them in the field at the same site beginning on eight different starting times over a year, beginning January 13 and at 45-day intervals. Each of the eight sets of litter bags was sampled four times over a period of 12 months, remaining litter mass was determined and k values were estimated. Temperature, precipitation, photosynthetically available radiation, soil water content and relative humidity were measured throughout the experiment.
    Important findings The remaining litter mass and k values were significantly different (p < 0.05) among the eight starting times. Rate of litter decomposition was significantly (p < 0.05) correlated to temperature and precipitation during the early phase rather than the later phase of the experiment. The k values ranged from 0.78 to 1.30, and were significantly higher (p < 0.001) for litter whose incubation started in the wet seasons as compared to the dry seasons. Therefore, time for the start of incubation may significantly influence estimation of k values, which in turn may influence estimation of ecosystem carbon balance.

    Influence of different detrending methods on climate signal in tree-ring chronologies in Wolong National Natural Reserve, western Sichuan, China
    LI Zong-Shan, LIU Guo-Hua, FU Bo-Jie, ZHANG Qi-Bing, HU Chan-Juan, and LUO Shu-Zheng
    Chin J Plan Ecolo. 2011, 35 (7):  707-721.  doi:10.3724/SP.J.1258.2011.00707
    Abstract ( 1955 )   PDF (1030KB) ( 1918 )   Save
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    Aims Tree rings are valuable for paleoenvironmental studies; however, the methods by which tree-ring series are processed are controversial. Our objective is to assess the impacts of different tree-ring detrending methods on climate-growth response patterns in Wolong National Natural Reserve, western Sichuan, China.
    Methods Fifty-four increment cores were taken from living trees of Abies faxoniana at a treeline site (3 450 m). We standardized tree-ring data with systematic growth forcing by five methods: conservative curve fits, 67% of series length and fixed 30 years, 60 years and 90 years cubic smoothing splines, and the resulted chronologies are abbreviated as CCF, CSS67%, CSS30, CSS60 and CSS90, respectively. We also composed the original tree-ring-width chronology (ORW) without standardization. Tree ring chronologies were correlated against (a) monthly climate data (mean, minimum and maximum temperatures, precipitation and relative humidity) from the nearby meteorological station and (b) monthly climate data (mean, minimum and maximum temperatures, precipitation and frequency of frost) from a high resolution gridded climate dataset.
    Important findings In spite of differences in the strength of growth-climate correlations among the chronologies, a similar linear response was the dominant mode. Radial growth was positively correlated with temperature in September of the prior year and March and July of the current year, as well as precipitation in October-December of the prior year and April and July in the current year. In contrast, radial growth was negatively correlated with relative humidity in November of the prior year and March of the current year, as well as frequency of frost in February-March and July-August of the current year. Of the climatic response patterns for different chronologies considered, CCF, CSS67%, CSS60 and CSS90 chronologies had average higher intercorrelations and the strongest climate signals. In contrast, CSS30 chronology exhibited weaker correlations with other chronologies, and showed a similar, albeit much lower sensitivity to climate. ORW chronology had the highest statistical values among the chronologies and could provide valuable climate information for tree-ring
    studies.

    Components of soil respiration and its temperature sensitivity in four types of forests along an elevational gradient in Shennongjia, China
    LUO Lu, SHEN Guo-Zhen, XIE Zong-Qiang, and ZHOU Li-Guang
    Chin J Plan Ecolo. 2011, 35 (7):  722-730.  doi:10.3724/SP.J.1258.2011.00722
    Abstract ( 1927 )   PDF (472KB) ( 1894 )   Save
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    Aims Quantifying forest soil respiration (Rs), its components of heterotrophic respiration (RH) and autotrophic respiration (RA), and their responses to temperature are vital to accurately evaluate response of the terrestrial carbon balance to future climate change. Our specific objectives were to (1) compare patterns of soil respiration of four types of forests, (2) evaluate relationships among soil respiration and temperature and water content and (3) find the regulation of Q10 value in relation to elevation.
    Methods Four types of forests along an elevational gradient at Shennongjia were investigated. The trenching plot approach was used to partition soil respiration into autotrophic respiration and heterotrophic respiration. Rates of soil respiration were measured twice a month from July 2009 to June 2010. Soil temperature and soil water content were measured at the same time.
    Important findings Annual soil respiration of the four types of forests was 1.63, 1.79, 1.74 and 1.35 μmol CO2·m–2·s–1, and annual heterotrophic respiration was 1.13, 1.12, 1.12, 0.80 μmol CO2·m–2·s–1. Soil respiration and its components displayed obvious seasonal dynamics, with maximum values in summer and minimum values in winter. The soil respiration flux of broad-leaved forest was significantly higher than that of coniferous forests, but there was no obvious differentiation between broad-leaved forests. Soil temperature was the main factor that affected soil respiration and its components, and there were significant exponential relationships between them. There was no significant relationship between soil water content and soil respiration flux, except in broad-leaved forest with a mild inhibition phenomenon. Q10 values of four types of forests were 2.38, 2.68, 2.99 and 4.24. Soil respiration was more sensitive to temperature along the elevation gradient, while Q10 value increased with elevation increase.

    Temporal and spatial patterns of soil respiration in subtropical forests of eastern China
    ZHOU Wen-Jia, SHI Zhao-Yong, and WANG Wei
    Chin J Plan Ecolo. 2011, 35 (7):  731-740.  doi:10.3724/SP.J.1258.2011.00731
    Abstract ( 2049 )   PDF (464KB) ( 1626 )   Save
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    Aims Soil respiration shows spatio-temporal differences at all scales because it is affected by diverse abiotic and biotic factors. Our objectives were to understand the seasonal dynamics and regional patterns of soil respiration in subtropical forests of eastern China and explore the possible underlying reasons.
    Methods We examined seasonal variations of soil respiration using a LI-8100 Soil Respiration System in 8 subtropical forests, belonging to three regions of eastern China, from August 2009 to October 2010. Soil temperatures at 5 cm depth were measured at the same time. We evaluated apparent Q10 values and annual CO2 efflux from soil to atmosphere at each site using the exponential relationship between soil respiration and soil temperature.
    Important findings Seasonal differences in soil respiration appeared at all sites, ranging from 2.64 to 6.24 μmol CO2·m–2·s–1. Soil respiration was higher in summer and lower in winter, following the seasonal dynamic of soil temperature. Soil temperature can explain 58.3%–90.2% of the variance of soil respiration for the year. Annual Q10 values from different sites ranged from 1.56 to 3.27. Annual soil CO2 efflux ranged from 1 077 to 2 058 g C·m–2·a–1 among all research sites in 2010, a high level of ecosystem CO2 efflux at the global scale.

    Effects of solar UV-B radiation on the efficiency of PSII photochemistry in the alpine plant Saussurea superba under different weather conditions in the Qinghai-Tibet Plateau of China
    SHI Sheng-Bo, SHANG Yan-Xia, ZHU Peng-Jin, YANG Li, and ZHANG Bo
    Chin J Plan Ecolo. 2011, 35 (7):  741-750.  doi:10.3724/SP.J.1258.2011.00741
    Abstract ( 1882 )   PDF (523KB) ( 1191 )   Save
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    Aims Strong solar UV-B radiation accompanied with strong solar visible radiation is a characteristic of the environment of China’s Qinghai-Tibet Plateau. Previous study confirmed that current ambient UV-B intensity has a small negative influence on the physiological response of the photosynthetic apparatus of the alpine plant Saussurea superba. Our objectives were to further analysis the influence of ambient UV-B intensity on PSII photochemistry efficiency under different weather conditions.
    Methods Short-term field experiments of UV-B were conducted during the luxuriant growing season in Kobresia humilis meadow in the Haibei Alpine Meadow Ecosystem Research Station. We used the pulse-modulated in vivo chlorophyll fluorescence technique to obtain rapid information on the effects of UV-B intensities on photosynthetic performances in the native alpine plant S. superba. The maximum quantum efficiency of PSII photochemistry (F(v)/F(m)) was measured after 3 minutes of dark radiation. The PSII photochemistry efficiency and non-photochemical quenching parameters were also measured. All chlorophyll fluorescence parameters were statistically analyzed with SPSS 11.0 software according to sunny, cloudy and shady weather states. Two-way ANOVA and least significant difference method (LSD) were used to compare differences among UV-B treatments and weather states.
    Important findings There were significant increases of F(v)/F(m) in both ambient UV-B and low UV-B treatments when the weather changed from clear days to overcast days. Although there were no significant differences, F(v)/F(m) showed an increased trend in low UV-B when compared with ambient UV-B in all three weather states. This suggests that ambient UV-B intensity can delay the recovery of optimal photochemistry efficiency in S. superba. There were (a) increased tendency in actual photochemical efficiency of PSII (ΦPSII) and photochemical quenching (qP) and (b) small decreased tendency in non-photochemical quenching (NPQ) in low UV-B treatment in comparison with ambient UV-B; however, all those fluorescence parameters were significantly changed among the three weather states. The variation of these PSII photochemistry efficiency parameters demonstrated that natural UV-B component can limit the photosynthetic performance. Further analysis confirmed that significant difference (p < 0.05 on sunny days and p < 0.01 on shady days) existed in relative limitation of quantum efficiency (L(PFD)) and fraction of opened PSII centers (qL). Although its effects were not always significant when compared with the influence of photosynthetically active radiation (PAR), UV-B radiation can influence primary quinine electron acceptor of PSII (QA) and there were negative effects on photosynthetic organization in S. superba.

    Effect of accumulated temperature on seed germination—a case study of 12 Compositae species on the eastern Qinghai-Tibet Plateau of China
    LIU Wen, LIU Kun, ZHANG Chun-Hui, and DU Guo-Zhen
    Chin J Plan Ecolo. 2011, 35 (7):  751-758.  doi:10.3724/SP.J.1258.2011.00751
    Abstract ( 2009 )   PDF (532KB) ( 1394 )   Save
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    Aim Temperature is an important environmental factor influencing seed germination. Our objective was to research the seed germination response of 12 Compositae species from the eastern Qinghai-Tibet Plateau of China to different temperatures using the accumulated temperature model.
    Methods All 12 species belong to four genera of Compositae. Seeds of each species were germinated at five constant temperatures (5, 10, 15, 20 and 25 °C), and germination was recorded once per day. We combined the logistic function and the accumulated temperature equation and used non-linear regression to estimate the base temperature and accumulated temperature for seed germination of each species.
    Important findings The average base temperature and accumulated temperature of the 12 species were 0 °C and 94.5 °C·d, respectively. The base temperature was lower and the accumulated temperature was higher than reported by previous researchers. These are the result of long-term adaptation to the temperature environment of the Qinghai-Tibet Plateau. There was a significant negative correlation between base temperature and accumulated temperature (p = 0.04). Therefore, species with lower base temperature would avoid the risk of seeds germinating earlier in an environment with changeable temperature. A significant positive correlation existed between seed mass and accumulated temperature (p = 0.01). Under relatively constant base temperature, small-seeded species germinated faster than large-seeded ones, giving them priority of germination in early succession.

    Responses of the spatial-temporal distribution of winter wheat (Triticum aestivum) roots and yield to different ratios of nitrogen sources
    XIONG Shu-Ping, WANG Xiao-Chun, LI Chun-Ming, MA Xin-Ming, DU Shao-Yong, ZHANG Ying-Wu, and LIN Shi-Zhao
    Chin J Plan Ecolo. 2011, 35 (7):  759-768.  doi:10.3724/SP.J.1258.2011.00759
    Abstract ( 1910 )   PDF (557KB) ( 1597 )   Save
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    Aims The study was conducted to reveal the effects of organic manure and urea on root spatial-temporal distributions, root turnover and yield in winter wheat (Triticum aestivum).
    Methods Using a minirhizotron root monitoring system, we studied root parameters (diameter, length density, increment, mortality and turnover) and yield of winter wheat ‘Yumai34’ under different fertilizer treatments (chicken manure and urea in ratios of 75 : 25, 50 : 50 and 25 : 75).
    Important findings Chicken manure and urea can increase root diameter, length density, increment, mortality and turnover in different growing stages. The 50 : 50 ratio of organic manure to urea had the greatest effect, significantly enhancing the above values. In contrast to no fertilizer treatment and urea treatment, the treatments of different ratios of organic manure to urea can significantly increase the number of effective tillers, grains per spike, grain weight per spike, economic yield and harvest index. Furthermore, both the economic yield and harvest index reached their highest values under the 50 : 50 treatment, and the differences with other treatments were statistically significant. Considering the general factors such as wheat grain yield and harvest index, the equivalent ratio of organic manure to urea had the largest effects and resulted in the highest wheat grain yield.

    Effect of high temperature on leaf senescence and related enzymes of grain starch synthesis in stay-green wheat after anthesis
    SHI Hui-Qing, GONG Yue-Hua, and ZHANG Dong-Wu
    Chin J Plan Ecolo. 2011, 35 (7):  769-778.  doi:10.3724/SP.J.1258.2011.00769
    Abstract ( 2127 )   PDF (613KB) ( 1738 )   Save
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    Aims Our objectives were to explore the influence of high temperature on enzymes of grain starch synthesis in stay-green wheat (Triticum aestivum) and reveal heat tolerance in stay-green wheat.
    Methods We used the stay-green wheat ‘Wm8’ and ‘Ym66’ and the control varieties ‘XY6’ and ‘XY22’ as experimental materials. A warming cover of plastic film was used to carry out the high-temperature treatment. After anthesis, we measured green leaf number, chlorophyll content, malonaldehyde (MDA) and membrane permeability, as well as the activities of the enzymes of grain starch synthesis were measured.
    Important findings High temperature after anthesis promotes rapid leaf senescence. For all four varieties, the green leaf number and chlorophyll content significantly decreased, but the MDA content and the relative electric conductivity increased markedly. The stay-green wheat varieties had higher green leaf number and chlorophyll content and lower MDA content and relative electric conductivity than the control cultivars after high temperature treatment. In grains, the activities of the enzymes of grain starch synthesis (sucrose synthase, SS; adenosine diphosphate glucose pyrophosphorylase, AGPP; and soluble starch synthase, SSS) in all four varieties decreased after high temperature treatment. But activities of these enzymes in the stay-green wheat were also higher than those in the control wheat, suggesting that it was beneficial for the starch accumulation in grain of stay-green wheat under high temperature. Among the three enzymes, a significant difference existed in SSS activity between the high temperature treatment and the control, and activities of the above three enzymes were positively and significantly correlated with grain-filling rate (r = 0.905, 0.419 and 0.801, respectively), so they play a key role in starch synthesis in the grain of wheat. Above all, the stay-green wheats have better resistance to high temperature than other varieties, and they have strong photosynthesis capacity and higher grain weight. Hence, breeding new cultivars with the stay-green characteristic would reduce the influence of high temperature stress during grain filling in wheat production.

    Effects of microenvironmental factors on rooting of Juniperus scopulorum cuttings
    MENG Peng, LI Yu-Ling, YOU Guo-Chun, and ZHANG Shuo
    Chin J Plan Ecolo. 2011, 35 (7):  779-788.  doi:10.3724/SP.J.1258.2011.00779
    Abstract ( 1758 )   PDF (612KB) ( 1602 )   Save
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    Aims Microenvironmental factors such as relative humidity, temperature and light intensity have significant effects on rooting. Our objective was to study the impact of microenvironmental factors on rooting of cuttings of Juniperus scopulorum (Rocky Mountain juniper), a native of western North America.
    Methods We used the softwood of eight-year-old J. scopulorum in a split plot experiment with five plots in river sand and peat substrates and two subplots in each plot with different cutting densities of 400 cuttings·m–2 (thin) and 1 666 cuttings·m–2 (dense). Data were analyzed using SPSS software.
    Important findings The rooting site, rate of callus-formation, rooting percentage, survival rate after training, root effect index (REI), rooting dispersion index (RDI) and fractal feature of J. scopulorum cuttings in the two densities were significantly different. Analysis of rooting percentage, survival rate after training, REI and RDI indicated that the integrated effect in dense cuttings was better than thin cuttings. The rooting ability of thin density cuttings was worse, but degree of rooting dispersion was higher. The average rooting fractal dimension of dense cuttings was significantly 1.24 times higher than of thin cuttings, and dense cuttings had changed rooting position and mechanism. Cuttings often produced induced roots in dense cuttings and primordial roots in thin cuttings. Different cutting densities resulted in significant different microenvironments of cuttings, whereas the regulating effect of different media in same density on microenvironment was limited. The microenvironmental humidity of dense cuttings was higher (up to 83.5%), while temperature and photosynthetically active radiation (PAR) were lower, leading to higher net photosynthetic rate (Pn) and lower transpiration rate (Tr). Within 60 days after insertion, Pn of cuttings in both dense and thin cuttings were rising, and the difference between them increased quickly with time. After 60 days, both were declining, and the difference between them remained relatively constant. Transpiration rate of dense cuttings remained relatively unchanged from 0 to 30 days, while Tr in thin cuttings displayed a rapid increase during the same periods. Transpiration rate of dense cuttings rose sharply in 30–60 days and peaked on the 60th day, but it was still lower than in thin cuttings. These results implied that the effect of microenvironmental factors on rooting of J. scopulorum cuttings was achieved by influencing physiological indexes and that disparity of nutriment status in the two cutting densities was a major cause of differences in the rooting mechanism.

    Erratum of Author
    Chin J Plan Ecolo. 2011, 35 (7):  788-788. 
    Abstract ( 1092 )   PDF (264KB) ( 1264 )   Save
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