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Table of Content
    Volume 35 Issue 4
    01 April 2011

    The tropical monsoon forest (TMF) landscape during the dry season in Yuanjiang of Yunnan, China, with which ZHU compared TMF with tropical rain forest in Yunnan in terms of distribution, physiognomy, floristic composition and geographical elements (Pages 463–470 of this issue). (Photographed by ZHU Hua)

      
    Research Articles
    Leaf nutrient stoichiometry of plants in the phosphorus-enriched soils of the Lake Dianchi watershed, southwestern China
    YAN Kai, FU Deng-Gao, HE Feng, DUAN Chang-Qun
    Chin J Plan Ecolo. 2011, 35 (4):  353-361.  doi:10.3724/SP.J.1258.2011.00353
    Abstract ( 2154 )   PDF (307KB) ( 2221 )   Save
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    Aims Understanding the stoichiometry of nutrient elements of plants growing in phosphorus-enriched areas can help characterize plant differentiation and guide ecological restoration in different biogeochemical environments. The Lake Dianchi watershed of southwestern China has P-enriched soils, and its main plant species may illustrate the relationship between plant ecological traits and the environment. Our aim was to test whether different plant life forms living at different P levels in this area have different patterns of leaf nutrient stoichiometry. Methods We collected leaf samples from 75 adult plants and soil samples from their root-zones in P-enriched areas and reference sites within the watershed. We determined N, P and K contents of leaves and total P contents of soil samples and calculated element ratios. Important findings The arithmetic means of leaf C, N and K were 441.42, 16.17 and 13.57 mg·g–1, respectively, and the geometric mean of leaf P was 1.92 mg·g–1. Significant correlations among leaf C, N, P and K were observed in all plant species. Higher P and K contents were observed in plants growing in higher P areas, but higher N/P and K/P were observed in lower P sites. Leaf nutrient concentration was significantly higher in herbaceous plants than in woody plants, but there was no difference in leaf nutrient concentrations between trees and shrubs. Leaf N/P and K/P were correlated negatively with soil P content. Results suggested that plant growth and vegetation development in the Lake Dianchi watershed were limited by low soil N contents and plant growth enhanced by N addition should be important for vegetation resilience and prevention of non-point source pollution in the process of ecosystem restoration.

    Effects of area, temperature and geometric constraints on elevational patterns of species richness: a case study in the Mountain Taibai, Qinling Mountains, China
    CHI Xiu-Lian, TANG Zhi-Yao
    Chin J Plan Ecolo. 2011, 35 (4):  362-370.  doi:10.3724/SP.J.1258.2011.00362
    Abstract ( 2930 )   PDF (357KB) ( 2389 )   Save
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    Aims Recent studies have illustrated that area, climate and geometric constraints were the main determinants of elevational patterns of species richness; however, the relative importance of these factors is unknown because these factors co-vary with elevation. Based on these factors, the power law species-area relationship (SAR), the metabolic theory of ecology (MTE) and the mid-domain effect hypothesis (MDE) have been proposed to explain elevational patterns of species richness. Our objective is to compare the relative performance of SAR, MTE and MDE in shaping elevational patterns of species richness, using vegetation and climatic data from Mt. Taibai, Qinling Mountains as a case study. Methods We used a database, “Distribution of Plants in Mt. Taibai”, composed of 2 132 plant species, to derive species richness values for different plant groups. A digital elevation model was used to calculate the area of each elevational band. Eighteen data loggers were set along south and north slopes and at different elevations to record air temperature. RangeModel software was applied to predict species richness of each elevational band, based on the MDE hypothesis. We then compared the explanatory strengths of SAR, MTE and MDE models and used variation partition and stepwise regression to assess their relative importance in shaping elevational patterns of species richness. Important findings Plant species richness followed a unimodal pattern; however, species richness of each plant group peaked at a different elevational band. As single predictors, SAR, MTE, and MDE explained 66.4%, 19.8% and 37.9% of the variation in species richness, respectively. Together they explained 84.6% of the variation. When the confounding effects of all other factors were eliminated, SAR and MTE explained most (25.5% and 17.7%), whereas MDE played a minor role. Furthermore, we found differences among taxonomic groups: the elevational pattern of lichen richness was primarily explained by MDE, that of ferns was jointly controlled by all three mechanisms and that of seed plants was mainly controlled by SAR and MTE.

    Temporal and spatial analysis of forest biomass in Changbai Mountains, Heilongjiang, China
    MAO Xue-Gang, FAN Wen-Yi, LI Ming-Ze, YU Ying, YANG Jin-Ming
    Chin J Plan Ecolo. 2011, 35 (4):  371-379.  doi:10.3724/SP.J.1258.2011.00371
    Abstract ( 1852 )   PDF (546KB) ( 1319 )   Save
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    Aims The objective is to obtain information on the spatial distribution and changes of forest biomass and carbon reserves to reveal patterns, discuss factors that drive change and analyze the environment of the forest. Methods Remote sensing information models were used to estimate forest biomass in Changbai Mountain of Heilongjiang based on remote sensing data and forest resource inventory data for four periods: the 1970s, 1980s, 1990s and early 21st century. Then temporal and spatial changes of forest biomass with elevation, slope and slope aspect were analyzed. Important findings Forest biomass in the four periods listed above averaged 81.56, 44.27, 48.27 and 54.82 t·hm–2, respectively. The total forest biomass in these periods was 5.37 × 108, 2.83 × 108, 3.06 × 108 and 3.46 × 108 t, respectively. Both variables initially decreased and then increased from the 1970s to the early 21st century. This pattern of change was consistent for forest biomass changes with elevation, slope and slope aspect in the four periods. The proportion of forest biomass in elevations of 200–400 m is about 35% and in slopes of 5°–15° is close to 50%. The proportion of forest biomass was about 7%–19% at southern and southwestern aspects and about 28% in plains.

    Effects of biological soil crusts on seedling growth and element uptake in five desert plants in Junggar Basin, western China
    ZHANG Yuan-Ming, NIE Hua-Li
    Chin J Plan Ecolo. 2011, 35 (4):  380-388.  doi:10.3724/SP.J.1258.2011.00380
    Abstract ( 2154 )   PDF (366KB) ( 1663 )   Save
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    Aims Biological soil crusts improve soil formation, increase landscape stability and fertility, prevent soil erosion by water or wind, and affect surface hydrological and nutrient cycles. Furthermore, biological soil crusts affect the germination, growth and establishment of vascular plants. The interaction between crusts and vascular plants is controversial, and the importance of biological crusts has not been well analyzed in the Gurbantunggut Desert of western China. Our objective was to examine effects of biological crusts on growth and nutrient uptake in vascular plants of the Gurbantunggut Desert. Methods We conducted manipulation experiments to examine the effects of biological crusts on growth and nutrient uptake in five typical, widely distributed species (Haloxylon persicum, Ephedra distachya, Ceratocarpus arenaarius, Malcolmia africana and Lappula semiglabra). We used shoot growth rate and above- and belowground biomass accumulation as indicators of seedling growth and the content of ten elements (N, P, K, Na, Mg, Fe, Mn, Cu, Zn and Na) as indicators of the influence of biological crusts on element uptake in the plants. Important findings Biological soil crusts significantly accelerated the growth rate of seedlings in all five species, but increased biomass accumulation only in herbaceous species, not in shrub species. Crusts also promoted early flowering and fruiting in herbaceous species, which could be beneficial to rapid establishment of herb communities before environmental resources become more available in other seasons. Crusts also influenced nutrient uptake by plants, especially N; the influence on uptake of other nutrients was species-specific. Therefore, biological soil crusts may be important in maintaining desert plant diversity.

    Seasonal dynamics of soil microorganisms and soil nutrients in fast-growing Populus plantation forests of different ages in Yili, Xinjiang, China
    AN Ran, GONG Ji-Rui, YOU Xin, GE Zhi-Wei, DUAN Qing-Wei, YAN Xin
    Chin J Plan Ecolo. 2011, 35 (4):  389-401.  doi:10.3724/SP.J.1258.2011.00389
    Abstract ( 1987 )   PDF (374KB) ( 1706 )   Save
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    Aims Our objective was to better understand the distribution and seasonal dynamics of soil microorganisms and soil nutrients of fast-growing Populus (Populus × euramericana) plantations of different ages (5, 10 and 15 years) in Yili Xinjiang, China. Methods We investigated the number and species composition of soil microorganisms and organic carbon/ nitrogen by means of plate count and conventional chemical methods, respectively. Important findings The three plantation forests were significantly different in microbial numbers and species compositions as affected by soil depth and season. The soil microbes were mainly distributed at 10–40 cm, and bacteria accounted the largest proportion. The total number of microorganisms and bacteria decreased with age, but the 15-year forest had the highest number of fungi and actinomycetes. The ratio of three kinds of microbial communities was relatively stable in soil and did not change with season. The content of soil organic carbon and nitrogen was mainly concentrated at 0–20 cm, decreased with increasing soil depth and responded differently to change of seasons and soil depth. Soil organic carbon increased with stand age, while nitrogen decreased and then increased. The correlation between soil microbes and soil organic carbon was negative, and the correlation between number of fungi and soil organic nitrogen was positive. The ratio of soil organic C/N was consistent with the ratio of bacteria number/ actinomycetes number, illustrating poplar plantation forests fix carbon and improve soil fertility.

    Comparison of three models of forest biomass estimation
    FAN Wen-Yi, ZHANG Hai-Yu, YU Ying, MAO Xue-Gang, YANG Jin-Ming
    Chin J Plan Ecolo. 2011, 35 (4):  402-410.  doi:10.3724/SP.J.1258.2011.00402
    Abstract ( 2028 )   PDF (384KB) ( 2327 )   Save
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    Aims Quantitative estimation of forest biomass is significant to studies of global carbon storage and carbon cycle. Our objective is to develop models to estimate forest biomass accurately. Methods Multi-stepwise regression model, traditional back propagation (BP) neutral network model and BP neutral network model based on Gaussian error function (Erf-BP) were developed to estimate forest biomass in Changbai Mountain of Heilongjiang, China according to TM imagery and 133 plots of forest inventory data. There were 71 dependent variables of geoscience and remote sensing. Important findings The precisions and root mean square errors of multi-stepwise regression model, traditional BP neutral network model and Erf-BP were 75%, 26.87 t·m–2; 80.92%, 21.44 t·m–2 and 82.22%, 20.83 t·m–2, respectively. Therefore, the relations between forest biomass and various factors can be better modeled and described by the improved Erf-BP.

    Use of storage water in Larix principis-ruprechtii and its response to soil water content and potential evapotranspiration: a modeling analysis
    SUN Lin, XIONG Wei, GUAN Wei, WANG Yan-Hui, and XU Li-Hong
    Chin J Plan Ecolo. 2011, 35 (4):  411-421.  doi:10.3724/SP.J.1258.2011.00411
    Abstract ( 2004 )   PDF (543KB) ( 1820 )   Save
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    Aims Water stored in the secondary xylem of the sapwood of large trees is not only a source for transpiration, but also may help avoid xylem cavitation and subsequent failure of water transfer in xylem. Our objective was to study the dynamics of tree water storage and use in order to understand the response mechanism of trees to water stress. Methods A model simulating the diurnal pattern of water transfer within stems was designed. It combines a non-steady-state hydraulic model with a transpiration model that was based upon the Penman-Monteith equation and a Jarvis-type representation of the stomatal resistance including xylem conduct water potential (ψhx), vapor pressure deficit (Ds) and photosynthetically active radiation (IP). The combined model simulates the diurnal variation of water uptake, storage flow and transpiration rate directly from environmental variables. We simulated the sap flow of Larix principis-ruprechtii, which is planted in Diediegou catchments on the north sides of the Liupan Mountains, and analyzed the relationship between storage water use and environmental factors. Important findings The hydraulic model accurately simulated diurnal patterns of measured sap flow under microclimatic conditions; the coefficient of determination (R2) between observed and simulated sap flow velocity in calibration sets was 0.91 (n = 2 532). On a typical sunny day, the highest rate of storage water use started at about 9:00 AM, decreased to zero at noon and turned to recharge throughout the afternoon until midnight. The daily storage water use varied between 0.04 and 0.58 mm?d–1 and was positively related to transpiration. Storage water provided 25.5% of transpiration water. When potential evapotranspiration (ETp) was < 4.9 mm?d–1, daily storage water use (DJz) was positively related to ETp. DJz linearly increased with ETp as ETp increased, but decreased correspondingly when ETp was >4.9 mmd–1. There was no significant relationship between DJz and soil water potential (p > 0.05), but the maximum DJz was positively related to soil water potential (R2 = 0.79). Therefore, ETp is the primary driving factor of water storage use, and soil water potential is the limiting factor.

    A functional-structural model for adults of Pinus tabulaeformis based on GreenLab
    Hong GUO Xiang-Dong LEI Veronique LETORT Yuan-Chang LU
    Chin J Plan Ecolo. 2011, 35 (4):  422-430.  doi:10.3724/SP.J.1258.2011.00422
    Abstract ( 1805 )   PDF (436KB) ( 1472 )   Save
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    Aims In functional-structural plant modeling, trees are composed of elements at the organ level and combined physiological processes and morphological structures. When it is applied to adult trees, we must deal with complexity of topology and consider ring growth. Our objective was to apply the functional structural model GreenLab to adult Pinus tabulaeformis trees and parameterize and validate the model. Methods Destructive sampling was done to collect detailed data including structure and biomass measurements from one 18-year and one 41-year P. tabulaeformis. To extend its application in adult tree growth analysis, we used substructure model to simplify tree topology and introduce ring biomass allocation parameter λ to mix Pressler model and common pool model to analyze tree ring growth in different ages and different environments. Direct parameters were attained from the measurement data, and hidden parameters of the model were calibrated using the generalized least squares method. The model was validated by comparing simulation data with observed data and comparing simulation data to data calculated by empirical model. Important findings Simulations of P. tabulaeformis growth based on the fitted parameters were reasonable. The coefficients of determination of linear regression equations between observations and predictions ranged from 0.84 to 0.98. The coefficient of determination of linear regression equations between GreenLab simulation data and empirical simulation data was 0.95. The results showed that the GreenLab model can be a new tool to simulate tree biomass at different growth cycles.

    Modeling rice grain starch accumulation based on plant carbon flow
    CHEN Jie, TANG Liang, LIU Xiao-Jun, CAO Wei-Xing, ZHU Yan
    Chin J Plan Ecolo. 2011, 35 (4):  431-440.  doi:10.3724/SP.J.1258.2011.00431
    Abstract ( 2274 )   PDF (496KB) ( 1337 )   Save
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    Aims Our objective was to develop a simulation model of grain starch formation in rice plants by analyzing the dynamic patterns of carbon assimilation and translocation under varied environmental factors and genetic types. Methods We used field experiments involving different eco-sites, growing seasons, cultivar types and nitrogen rates in developing a model of grain starch accumulation. Important findings The model proposed that the rate of grain starch accumulation was determined by (a) carbon availability restricted by source and (b) carbon accumulation rate restricted by sink. Carbon accumulation rate restricted by sink was dependent on the potential starch accumulation rate and the interaction of influencing factors: temperature, water, nitrogen conditions within plants and the ability of carbon translation into starch. Carbon availability in grains restricted by source was the sum of carbon assimilation from the photosynthetic organs and remobilization from the vegetative organs after anthesis. Photosynthetic product transported to grain directly after anthesis exhibited a logarithmic relationship to post-anthesis growing degree days. Post-anthesis carbon remobilization from the vegetative organs included remobilization from leaves and stems. Testing of the model with independent datasets involving different years, eco-sites, varieties and nitrogen rates indicated values of RMSE of 3.61% and 4.51% and R2 of 0.994 and 0.959 for starch accumulation and content, respectively. Results showed that the model could predict accumulation and content of grain starch in rice under different cultivated conditions, which provides a quantitative tool for quality prediction and regulation.

    Effects of short time heat stress on photosystem II, Rubisco activities and oxidative radicals in Alhagi sparsifolia
    XUE Wei, LI Xiang-Yi, LIN Li-Sha, WANG Ying-Ju, LI Lei
    Chin J Plan Ecolo. 2011, 35 (4):  441-451.  doi:10.3724/SP.J.1258.2011.00441
    Abstract ( 2119 )   PDF (622KB) ( 1726 )   Save
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    Aims Our general objective was to determine the effects of short time heat stress on photosystem II (PSII) activity and Rubisco activity in Alhagi sparsifolia. Specifically, we wanted to determine that temperature range within which the plant can photosynthesize, the critical temperature that damaged leaves and characters of reactive oxidative accumulation under high temperature. Methods Samples of A. sparsifolia were collected on a sunny morning with low winds in early August 2010. We selected healthy growing shoots randomly, washed them lightly to remove leaf dust, cut and quickly inserted them into damp soil and covered them with a plastic cover. Samples were immediately put into black plastic bags, which contained damp filter papers. The bags were placed into a heat-resistant case for transport to the laboratory and then immersed in water baths for 15 min at temperatures of 30, 38, 43, 48, 53, 58 and 63 ℃. Twenty intact and mature leaves were used to measure leaf fluorescence and CO2 response curves at each temperature. Important findings At leaf temperatures up to 43 ℃, the maximum photochemical efficiency of PSII, number of active reaction centers and leaf vitality index all decreased markedly. At moderately high temperatures, the electron donors of PSII were more heat-vulnerable than the electron acceptors of PSII, and the appearance of fluorescence K point (300 μs) in the fluorescence curve at 58 ℃ indicated that the structure of oxygen-evolving complexes was damaged, resulting in loss of oxygen-evolving function. At higher leaf temperatures, the activity of Rubisco first increased and then decreased, with a maximum at 34 ℃. Under high temperature stress, considerable oxidative radicals, e.g., ammoniacal nitrogen, H2O2 and O2–· were produced and continually accumulated in cells. We conclude that heat stress has strong impacts on both light reaction and dark reaction phases of photosynthesis, especially their two heat sensitive components comprised of PSII and Rubisco.

    A feasible method for measuring photosynthesis in vitro for major tree species in northeastern China
    TANG Yan, WANG Chuan-Kuan
    Chin J Plan Ecolo. 2011, 35 (4):  452-462.  doi:10.3724/SP.J.1258.2011.00452
    Abstract ( 1896 )   PDF (421KB) ( 2125 )   Save
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    Aims Tree leaf photosynthesis is often difficult to measure in situ because of the physical inaccessibility of the tree canopy. One simple, inexpensive solution is to measure photosynthesis in vitro, but its validity and reliability for specific tree species need verification. Our goals were to determine (a) which in vitro measurement methods would result in detached leaves maintaining as high photosynthetic activity as in situ, (b) how long the photosynthetic activity of detached leaves can be sustained and (c) the reliability and feasibility of in vitro measurements. Methods We selected seven major tree species with divergent ecophysiological characteristics in the temperate forest of northeastern China: coniferous (Pinus koraiensis and Larix olgensis), diffuse-porous (Betula platyphylla and Juglans mandshurica) and ring-porous (Fraxinus mandshurica, Ulmus macrocarpa and Quercus mongolica) species. We used the time for the photosynthetic rate to recover 90% of its pre-photoinducement value (T90) and leaf transpiration rate (E) to assess the water supply and photosynthetic activity of detached leaves. Based on this, we determined an optimal in vitro protocol for measuring photosynthesis of detached leaves. We simultaneously monitored the duration of relatively stable photosynthetic rates after leaves had been detached. We then compared the differences in gas exchange parameters between in situ and in vitro measurements with the chosen protocol to determine the reliability of the protocol for each tree species. Important findings The detached leaves of all measured tree species except for Q. mongolica had the potential to maintain relatively high, stable water supply and photosynthetic activity. The optimal protocol of in vitro photosynthesis measurements for the other six tree species was to insert the twigs or compound leaves into water immediately following detaching, girdle phloem about 3 cm from the cut and remove all leaves except the target ones. T90 differed significantly among the six tree species (p < 0.05), and the ring-porous tree species had significantly greater T90 than the other species. The leaf water supply and photosynthetic activity for the six species was effectively maintained for one hour following detachment, during which most of the gas exchange parameters measured did not differ significantly between in situ and in vitro measurements. Therefore, this study provided a feasible protocol of in vitro measurement of leaf photosynthesis for the six temperate tree species.

    Review
    Tropical monsoon forest in Yunnan with comparison to the tropical rain forest
    Zhu Hua
    Chin J Plan Ecolo. 2011, 35 (4):  463-470.  doi:10.3724/SP.J.1258.2011.00463
    Abstract ( 2737 )   PDF (333KB) ( 1716 )   Save
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    In Chinese botanical literature, the term “tropical monsoon forest” is explained and used inconsistently and is often confused with tropical rain forest. My objective is to clarify differences between the two forests. Schimper defined tropical monsoon forest as being more or less leafless during the dry season and considered it a transitional vegetation type between tropical rain forest and savanna in terms of physiognomy and distribution. I compared tropical monsoon forest and rain forest in physiognomy, floristic composition and geographical elements to describe and characterize the monsoon forest in Yunnan, China. The tropical monsoon forest in Yunnan occurs mainly on river banks and in basins of several large rivers below 1 000 m altitude. The forest has one or two tree layers, and trees of at least the top layer are deciduous in the dry season. In life forms, the forest is rich in hemicryptophytes and relatively rich in geophytes and therophytes, but less rich in woody lianas and almost lacks megaphanerophytes and chamaephytes compared to tropical rain forest. In leaf size and form, the forest has more microphyllous leaves and compound leaves (24% and 44% of tree species, respectively) than tropical rain forest. In terms of floristic elements, the forest has a greater percentage of species of pantropic distribution (30% of the genera) and tropical Asia and tropical Africa disjunct distribution than tropical rain forest. Thus, the tropical monsoon forest in Yunnan has more diverse geographical elements in its flora and a complicated evolution history.


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