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Table of Content
    Volume 34 Issue 3
    01 March 2010

    A typical landscape of karst cluster-peak depression in Mulun National Nature Reserve, Guangxi Zhuang Autonomous Region, where Song et al. investigated spatial pattern of forest communities in relation to the environmental factors (pages 298

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    Research Articles
    Spatial patterns of Castanopsis eyrei and Schima superba in mid-subtropical broad- leaved evergreen forest in Gutianshan National Reserve, China
    LI Li, CHEN Jian-Hua, REN Hai-Bao, MI Xiang-Cheng, YU Ming-Jian, YANG Bo
    Chin J Plant Ecol. 2010, 34 (3):  241-252.  doi:10.3773/j.issn.1005-264x.2010.03.001
    Abstract ( 3124 )   Full Text ( 15 )   PDF (892KB) ( 2144 )   Save
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    Aims Many mechanisms of forest patterns have been examined in tropical rain forest; however, there are only a handful of similar studies on subtropical broad-leaved evergreen forest. Our objective is to analyze the main mechanisms of distribution pattern of Castanopsis eyrei and Schima superba in GTS (Gutianshan) forest plot.

    Methods Based on a stem map of a 24 hm2 permanent plot in the middle subtropical broad-leaved evergreen forest at Gutianshan National Reserve, we analyzed the distribution pattern of the dominant species C. eyrei and S. superba in saplings, juvenile trees, adult trees, large trees and old trees using spatial point pattern analysis. We also examined spatial associations among different growth stages.

    Important findings Castanopsis eyrei and S. superba had a clustered distribution across a range of scales (0-100 m). Saplings, juvenile trees and adult trees tended to be more clumped than big trees. Old trees tended to be somewhat more clumped than big trees. Our results suggested that the two species have obvious habitat preferences at larger scales. For C. eyrei, saplings were significantly positively associated with juvenile trees at scales ≤ 100 m, as were saplings and adult trees, juvenile trees and adult trees, adult trees and big trees. Generally there was no correlation between big trees and old trees at scales ≤ 10 m, whereas their association tended to be positive at larger scales (10-100 m). Generally there were negative or no correlations between other size classes. For S. superba, the saplings were significantly positively associated with juvenile trees at scales ≤ 100 m, as were saplings and adult trees, juvenile trees and adult trees. Generally there were negative or no correlations between juvenile trees and old trees, adult trees and old trees, big trees and old trees, saplings and big trees, juvenile trees and big trees, adult trees and big trees. Generally there was negative correlation between saplings and old trees at scales ≤ 20 m, whereas their association tended to be positively at larger scales (25-100 m). These results suggested that dominant species facilitated coexistence of other species through emptying space for colonization of other species, which is probably attributed to density dependence or the Janzen-Connell effect. Both processes depended on species in intensity and acting time.

    Adaptive regulation in reproductive strategy of two bunchgrasses under mowing disturbance in Inner Mongolia grassland
    ZHANG Xiao-Na, HADA ChaoLu, PAN Qing-Min
    Chin J Plant Ecol. 2010, 34 (3):  253-262.  doi:10.3773/j.issn.1005-264x.2010.03.002
    Abstract ( 2846 )   Full Text ( 2 )   PDF (443KB) ( 3190 )   Save
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    Aims Stipa grandis and Cleistogenes squarrosa are two important bunchgrass species in Inner Mongolia typical steppe. Stipa grandis is a dominant species in undisturbed communities, while C. squarrosa becomes the dominant species in degraded communities. It is important to understand the regulation mechanisms of the two populations under mowing disturbance, especially those regulating sexual and asexual reproduction. We addressed four questions: 1) Do the two populations exhibit density-dependent regulation under mowing disturbance? 2) If so, how do they regulate sexual and asexual reproduction? 3) Do the species modify their biomass allocation patterns under mowing disturbance, and, if so, how do they change their allocation patterns? 4) Does mowing disturbance affect plant basal area and tiller number?

    Methods This study was conducted in a long-term fenced site and a long-term mowed site at the Inner Mongolia Grassland Ecosystem Research Station of Chinese Academy of Sciences in 2007. We examined the density regulation and resource allocation regulation of S. grandis and C. squarrosa under different management regimes.

    Important findings Under mowing disturbance, S. grandis exhibited no significant change in population biomass, while C. squarrosa significantly increased. Because mean plant biomass of S. grandis decreased significantly and that of C. squarrosa did not change, density increase plays an important role for the two species in population biomass production. The two species exhibited different strategies in density-dependent regulation of asexual and sexual reproductive processes. For S. grandis, density increased in non-reproductive plants, but was unchanged in reproductive plants under mowing disturbance, which led to relative density increasing in non-reproductive plants and decreasing in reproductive plants. For C. squarrosa, the densities of both reproductive and non-reproductive plants increased significantly at the mowed site. The relative density increased in reproductive plants, but decreased in non-reproductive plants. The two species showed opposite reproductive allocation manipulation strategies under mowing disturbance. Stipa grandis significantly decreased reproductive biomass allocation by decreasing the biomass fraction of spikes in reproductive tillers. In contrast, C. squarrosa significantly increased reproductive biomass allocation by increasing the fraction of reproductive tiller biomass in plant biomass. No significant changes were found in S. grandis basal area and tiller number under mowing disturbance. Likewise, no significant change was found in C. squarrosa tiller number, but its basal area significantly decreased.

    Short-term gas exchange responses of Betula utilis to simulated global warming in a timberline ecotone, eastern Tibetan Plateau, China
    XU Zhen-Feng, HU Ting-Xing, ZHANG Li, ZHANG Yuan-Bin, XIAN Jun-Ren, WANG Kai-Yun
    Chin J Plant Ecol. 2010, 34 (3):  263-270.  doi:10.3773/j.issn.1005-264x.2010.03.003
    Abstract ( 2806 )   Full Text ( 5 )   PDF (392KB) ( 1629 )   Save
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    Aims Betula utilis is an important plant in the timberline ecotone of subalpine regions, Western Sichuan China. Our objective is to determine how this species changes its photosynthetic parameters under warming conditions.

    Methods We studied the responses of gas exchange to simulated global warming using the open-top chamber (OTC) method. During the 2007 growing season, microclimate data between the OTC and the control (CK) were taken at 15-min intervals with an automatic recording system. In mid-August, the gas exchange of B. utilis seedlings in the OTC and the CK was measured with the LI-6400 Portable Photosynthesis System and a 6-cm2 leaf chamber. Comparisons between the OTCs and the control plots were analyzed by the Wilcoxon’s signed ranks test.

    Important findings Warming significantly increased instantaneous leaf net photosynthetic rate (Pn), conductance (Gs) and transpiration (Tr) by 17.4%, 21.4% and 33.9%, respectively, and reduced leaf N concentration by 12.4%. Warming also enhanced the maximum net photosynthetic rate (Pnmax) (+19.6%), dark respiration rate (Rd) (+14.3%) and apparent quantum yield (AQY) (+7.9%), but did not influence the light compensation point (LCP) or the light saturation point (LSP) of B. utilis seedlings. Moreover, warming markedly increased the maximum rate of RuBP carboxylation (Vcmax) and rate of photosynthetic election transport (J), but there were no clear differences between treatments for triose phosphate use (TPU) and compensation CO2 (CCP). Our results indicated that in situ experimental warming had positive effects on the gas exchange of B. utilis seedlings. These responses could be helpful for the timberline species to adapt to future global warming.

    Effects of post-anthesis irrigation on degree of polymerization of storage protein and rheological properties in wheat
    YAO Feng-Juan, HE Ming-Rong, JIA Dian-Yong, DAI Xing-Long, CAO Qian
    Chin J Plant Ecol. 2010, 34 (3):  271-278.  doi:10.3773/j.issn.1005-264x.2010.03.004
    Abstract ( 2409 )   Full Text ( 1 )   PDF (364KB) ( 1135 )   Save
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    Aims Our objective was to verify the relationship between worsening dough rheological properties caused by pre-harvest irrigation and degree of polymerization of storage protein in wheat.

    Methods We applied three irrigation regimes (none, 14 days after anthesis and both 14 and 28 days after anthesis) to the Jimai 20 cultivar of wheat and examined effects on grain yield, parameters representing polymerization of storage protein and dough rheological properties.

    Important findings Grain yield was highest and both dough development time and dough stability time were longest with the single post-anthesis irrigation, while the second irrigation led to shortened dough development time and dough stability time and weakened gluten strength, as well as decreased glutenin polymerization index and average size of glutenin macopolymer (GMP). Stepwise correlation analysis suggested that the poorer dough rheological properties and weakened gluten strength with two post-anthesis irrigations resulted mainly from reduced GMP particle size.

    Effects of elevated temperature and [CO2] under different nitrogen regimes on biomass and its allocation in Quercus mongolica seedlings
    MA Li-Xiang, ZHAO Meng, MAO Zi-Jun, LIU Lin-Xin, ZHAO Xi-Zhu
    Chin J Plant Ecol. 2010, 34 (3):  279-288.  doi:10.3773/j.issn.1005-264x.2010.03.005
    Abstract ( 2704 )   Full Text ( 4 )   PDF (702KB) ( 2776 )   Save
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    Aims The cold temperate zone is very sensitive to climate change. Forests in this region provide a natural laboratory for studying effects of climate warming on terrestrial ecosystems. Our objective was to study the biomass responses of seedlings of a main secondary forest species, Quercus mongolica, to experimental warming and the interaction of elevated CO2 and different nitrogen regimes to provide insights into community development under a future warmer climate.

    Methods We used large growth chambers to determine short-term effects of elevated temperature (+ 4 °C) (ET) only and the combination of elevated CO2 concentration (700 μmol CO2·mol-1) and elevated temperature (+ 4 °C) (ECET) under three different nitrogen regimes (15 mmol·L-1 N (N1), 7.5 mmol·L-1 N (N2) and no added N in soil substrate (N3)) on growth, biomass and its allocation in Q. mongolica seedlings.

    Important findings The ET and N1 combination generally increased growth in height and diameter, as well as biomass accumulation of the seedlings. The allocation of underground biomass of seedlings increased with the increasing of N concentration. The ETEC and N1 combination increased growth in height and underground biomass allocation of the seedlings, but there was no significant effect on diameter growth and total biomass of the seedlings. The C/N ratio of leaves increased with decreasing nitrogen supply, but the increases of C/N ratio under ECET was due to decreasing nitrogen concentration in the leaves and under ET was due to increasing carbon concentration in the leaves. No promotion of biomass accumulation was found under ECET and ET with lower nitrogen supply. So nitrogen supply will be an important factor with future climate change. Sufficient nitrogen supply may promote the growth of Q. mongolica seedlings, lead to changes in regeneration dynamics and increase their carbon stock under the future climate.

    Responses and regulation of canopy microclimate on formation spike from tillers of two types of wheat
    LI Na-Na, TIAN Qi-Zhuo, WANG Shu-Liang, XIE Lian-Jie, PEI Yan-Ting, LI Hui
    Chin J Plant Ecol. 2010, 34 (3):  289-297.  doi:10.3773/j.issn.1005-264x.2010.03.006
    Abstract ( 2574 )   Full Text ( 2 )   PDF (357KB) ( 1650 )   Save
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    Aims Wheat (Triticum aestivum) tillering characteristics provide an important basis for controlling population dynamic structure. However, studies on maximum tillering potential and different sowing methods and row spacings are lacking for different varieties. Our objective was to examine the maximum tillering potential and explore proper sowing methods and row allocation to increase the yield of different tillering types.

    Methods The experiment was conducted on the farm of Shandong Agricultural University, Tai’an, China, using large-spike (Shannong 8355 and Lankao Aizao 8) and multiple-spike (Jimai 20 and Lumai 14) cultivars. Broadcast and seed drilling (row spacing of 30, 25, 20 and 15 cm) treatments were used in a randomized complete block design with three replications. Every treatment added dibble seeding with 30 cm plant spacing. Plot area is 8 m2.

    Important findings The two types have higher tillering ability with dibble seeding, but there are significant differences in spike number and spike rate. Canopy microclimate has greater influence on the two types than do genetic factors. The large-spike cultivar has a higher degree of response on the colony environment than the multiple-spike cultivar. Canopy structure can be effectively controlled by seeding mode. Drilling makes significantly higher economic yield than broadcast seeding. The degree of response to row spacing differs among the varieties. It is suggested that a suitable combination of cultivar and row spacing could effectively increase grain yield, with the row spacing 23.4-23.9 cm for multiple-spike cultivars and 16.5-16.9 cm for large-spike cultivars. Broadcast seeding and narrow spacing drill seeding increase tillering and the canopy light interception (LI) of the upper and central portion in the booting and filling stage, but reduce the number of grains and kernel weight. After the booting stage, seeding mode affects CO2 concentration of every layer, although not significantly.

    Spatial pattern of forest communities and environmental interpretation in Mulun National Nature Reserve, karst cluster-peak depression region
    SONG Tong-Qing, PENG Wan-Xia, ZENG Fu-Ping, WANG Ke-Lin, QIN Wen-Geng, TAN Wei-Ning, LIU Lu, DU Hu, LU Shi-Yang
    Chin J Plant Ecol. 2010, 34 (3):  298-308.  doi:10.3773/j.issn.1005-264x.2010.03.007
    Abstract ( 2683 )   Full Text ( 4 )   PDF (531KB) ( 2018 )   Save
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    Aims Mulun National Nature Reserve is rich in typical natural evergreen and deciduous broad-leaved forest communities. However, little is known about the spatial pattern of vegetation and its relation with environment. Our objective was to investigate the spatial pattern of woody vegetation (DBH ≥ 1 cm) communities and its environmental interpretation.

    Methods Fifty sample plots of 20 m × 20 m dimensions were established based on microhabitats and vegetation community types in Mulun National Nature Reserve, typical karst cluster-peak depression region. We analyzed data collected on woody plants (DBH ≥ 1 cm) in the plots, spatial pattern of woody vegetation communities and relationships with environmental factors (10 soil factors and 5 topographical factors) using two-way indicator species analysis (TWINSPAN) and detrended canonical correspondence analysis (DCCA).

    Important findings The forest communities were divided into 11 vegetation groups and were classified into 4 eco-types at the third level by TWINSPAN. The first DCCA axis accounted for the largest fraction of the variation of the ordination and showed gradients of slope direction and major soil nutrients. Along the first axis, the pattern of communities ranged from primary forest with shade-tolerant plants towards secondary and manmade forests with shade-intolerant and pioneer plants, accompanying a shift from shady to sunny slopes, an increase in the ratio of bare rocks in the ground cover and a steady decline in major soil nutrients. The effects of soil environmental factors, spatial factors and their interaction on the total variation of forest communities’ pattern were quantitatively partitioned following Borcard et al. and showed that the contribution rates were 21.02% for soil environmental factors separately, 18.15% for soil environmental factors coupled with spatial factors, 13.16% for spatial factors separately and 47.66% for other undetermined factors. This indicated species coexistence was controlled by both niche differentiation and unified neutral theory of biodiversity.

    Influence of environmental factors on phylogenetic structure at multiple spatial scales in an evergreen broad-leaved forest of China
    HUANG Jian-Xiong, ZHENG Feng-Ying, MI Xiang-Cheng
    Chin J Plant Ecol. 2010, 34 (3):  309-315.  doi:10.3773/j.issn.1005-264x.2010.03.008
    Abstract ( 2623 )   Full Text ( 8 )   PDF (471KB) ( 1654 )   Save
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    Aims Phylogenetic structure of a community is a synthetical indicator reflecting underlying ecological processes. Understanding of the phylogenetic structure of a community will provide insights into the relative importance of different processes structuring the community. Our objectives are 1) examine the effects of environmental factors on phylogenetic structure; 2) test the prediction of neutral theory that the community is randomly assembled and the prediction of niche theory that the community is mainly determined by niche differentiation; and 3) determine the relative importance of neutral theory and niche theory in biodiversity maintenance in subtropical evergreen broadleaved forest.

    Methods Gutianshan forest dynamic plot is located in the Gutianshan National Nature Reserve at Kaihua County, Zhejian Province of China. We randomly chose 1 000 subplots at five spatial scales of radii 5, 25, 50, 75 and 100 m in the Gutianshan forest dynamic plot and analyzed phylogenetic structure of subplots at these scales with net relatedness index (NRI). We analyzed the effect of environmental factors, including topographical factors, such as altitude, slope, aspect and convexity, and edaphic factors such as soil moisture, pH and 16 soil nutrients, on the community phylogenetic structure with multivariate regression.

    Important findings Communities were phylogenetically clustered at all spatial scales, indicating that trees were more closely related to their neighbors than expected by chance. With increasing scale, the strength of clustering increased and then deceased. Multiple linear regression showed that environmental factors had almost no effect on phylogenetic structure at smaller scales, but strongly affected the community structure at larger scales (radius of 100 m). At the radius of 100 m, two types of different phylogenetic structure emerged: some of subplots kept clustering, yet others became overdispersed. The difference of phylogenetic community structures at scale of 100 m was mainly determined by altitude. Our results support the prediction of niche theory that the community phylogenetic structure is structured by niche differentiation, and do not support the prediction that the community phylogenetic structure is randomly assembled by ecological drift and dispersal limitation.

    Phenological change of main vegetation types along a North-South Transect of Eastern China
    YU Zhen, SUN Peng-Sen, LIU Shi-Rong
    Chin J Plant Ecol. 2010, 34 (3):  316-329.  doi:10.3773/j.issn.1005-264x.2010.03.009
    Abstract ( 2810 )   Full Text ( 6 )   PDF (681KB) ( 1832 )   Save
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    Aims Vegetation phenology is a sensitive indicator of ecological response to climate change that is usually used as an important component of dynamic vegetation models and reflects dynamic of carbon and water exchange between the land surface and the atmosphere.

    Methods Based on the biweekly dataset of NOAA/AVHRR NDVI (Normalized Difference Vegetation Index) for 1982-2006, the phenological curves of main vegetation types along the North-South Transect of Eastern China (NSTEC) were extracted using remote sensing software ENVI (ver4.3, RSI). A smooth-splin method was used to simulate and develop smooth phonological curves, which were used to determine timing of main phenological events by the first derivative method.

    Important findings Earlier onsets of green-up were found in Temperate Coniferous Forest (TCF, 0.56 d·a-1), Temperate Grassland (TG, 0.66 d·a-1), Subtropical and Tropical Coniferous Forest (STCF, 0.46 d·a-1), Subtropical Deciduous Broadleaf Forest (SDBF, 0.58 d·a-1), Subtropical and Tropical Grassland (STG, 0.89 d·a-1). Delays of dormancy were found in Temperate and Cold Temperate Coniferous Forest (TCTCF, 0.32 d·a-1), Subtropical Deciduous Broadleaf Forest (SDBF, 0.80 d·a-1) and Temperate Deciduous Forest (TDF, 0.18 d·a-1). Prolonged growing season lengths (GSL) were also found in most vegetation types in the transect; however, these differed in their onsets dates of green-up or dormancy. Prolonged GSL in TCF (0.77 d·a-1) was caused by earlier onset of green-up, prolonged GSL in TCTCF (0.38 d·a-1) and TDBF (0.36 d·a-1) were caused by delays of dormancy and prolonged of GSL in TG (0.76 d·a-1), STCF (0.83 d·a-1), SDBF (1.4 d·a-1) and STG (1.3 d·a-1) were due to both advances of green-up and delays of dormancy. Correlations among precipitation, temperature and NDVI were analyzed to further explore the causes of phenological variation. The result showed that temperature has greater influence on variations of phonological events than precipitation. Heat gradient along NSTEC caused a phonological events gradient, i.e., a time sequence of cold temperate zone > temperate zone > subtropical zone in the onset dates of green-up and subtropical zone > temperate zone > cold temperate zone in the onset dates of dormancy and growing season lengths.

    Simulation of biomass and soil desiccation of Robinia pseudoacacia forestlands on semi-arid and semi-humid regions of China’s Loess Plateau
    LI Jun, WANG Xue-Chun, SHAO Ming-An, ZHAO Yu-Juan, LI Xiao-Fang
    Chin J Plant Ecol. 2010, 34 (3):  330-339.  doi:10.3773/j.issn.1005-264x.2010.03.010
    Abstract ( 2635 )   Full Text ( 6 )   PDF (596KB) ( 1407 )   Save
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    Aims Deep soil desiccation so commonly occurs in black locust (Robinia pseudoacacia) forestlands of China’s Loess Plateau that it increasingly counteracts artificial vegetation construction. We analyzed and compared black locust forestlands under different rainfall regions in the Loess Plateau in terms of biomass and incidence and regional distribution of deep soil desiccation in order to provide scientific foundations for constructing black locust forestlands according to local conditions of the Loess Plateau.

    Methods Based on datasets of weather, soil and crop parameters and simulation precision verification, we researched biomass and deep soil desiccation in the 1- to 45-year-old block of black locust forestlands of Luochuan and Changwu in the semi-humid region and Yan’an and Guyuan in the semi-arid region of the Loess Plateau from 1957 to 2001 using the WinEPIC model.

    Important findings In Luochuan, Changwu, Yan’an and Guyuan, simulated annual net productivities of the 1- to 45-year-old black locust forestlands averaged 5.33 × 103, 4.56 × 103, 4.03 × 103 and 3.35 × 103 kg·hm-2·a-1, respectively. Productivity peaked when forestlands were 5- to 8-year-old and then tended to decrease in a pattern that followed the fluctuation of annual rainfall. In 1- to 7-year-old forestlands, annual water consumptions were higher than annual rainfalls, which resulted in soil drying at 0-10 m depth; soil desiccation rates in Luochuan, Changwu, Yan’an and Guyuan were 164.3, 165.7, 187.1 and 190.0 mm per year, respectively. In 8- to 45-year-old forestlands, the available water fluctuated at a low level within 0-250 mm as annual rainfalls varied. In 1- to 9-year-old forestlands, the 0-10 m soil humidity profiles sharply varied, with annual declines and thickening of dry soil layers. In 7- to 9-year-old forestlands dry soil layers exceeded 10 m thick, and in 8- to 45-year-old forestlands the dry soil layers had relatively stable water humidity. In forestlands of Luochuan and Changwu, the annual net productivities were high and relatively stable, and the growth periods of black locust could exceed 45 years. In forestlands of Yan’an and Guyuan, the annual net productivities were low and instable, and stable growth periods did not exceed 40 years.

    Effect of simulated ortet density on growth and clonal propagation of Iris japonica
    WANG Yong-Jian, ZHONG Zhang-Cheng
    Chin J Plant Ecol. 2010, 34 (3):  340-347.  doi:10.3773/j.issn.1005-264x.2010.03.011
    Abstract ( 2197 )   Full Text ( 1 )   PDF (495KB) ( 2296 )   Save
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    Aims Intra-species ortet competition has significant effects on growth, sexual reproduction and clonal propagation of clonal plants. Iris japonica is widely distributed along open area of forest edges and under sparse forest canopies with higher light and water conditions in southern China. It affects other herbs by its dominance through clonal propagation. Our objective was to determine the effect of different initial ortets of I. japonica on clonal propagation and growth. Findings could provide a theoretical foundation for the management of understory vegetation with I. japonica.

    Methods From September 2007 to June 2008, we conducted a simulation experiment of I. japonica in which we replaced a ortet by an independent one-year ramet. We set up three treatments: one initial separate ortet (O), two initial separate ortets (T) and four initial separate ortets (F) in 0.7 m × 0.7 m, which represented the effect of intra-species ortet competition. Each treatment had 10 repeats, and we quantitatively measured characters of clonal propagation, leaves and biomass and allocation of clonal propagation in different treatments. Data were analyzed using SPSS software.

    Important findings The number of new ramets per ortet of I. japonica was higher, and number of dead ramets per ortet was lower in O treatment than in T and F treatments. Number of primary and secondary daughter ramet (per ortet) and length, surface, volume and length per density of fine rhizomes and roots of I. japonica decreased with the increase of initial ortet (ortet competition). The number of highly withered and total withered leaves of mother ramet, and number of moderately withered, highly withered and total withered leaves of daughter ramet of I. japonica increased with the increase of initial ortet (ortet competition). Leaf area and number of leaves per ortet and number of leaves for daughter ramet per ortet of I. japonica significantly decreased, and leaf area ratio (LAR) per ortet significantly increased with the increase of initial ortet (ortet competition). Biomass of fine rhizomes, coarse rhizomes, clonal propagation, aboveground, belowground and total plant and allocation to fine rhizome and belowground of I. japonica significantly decreased, and allocation to coarse rhizome of mother ramet and aboveground significantly increased with the increase of initial ortet (ortet competition). In sum, with the increase of ortet competition, growth of I. japonica and status of its leaves were inhibited, and clonal propagation became weaker. Thus, it could increase LAR and allocation of coarse rhizome of mother for resources reserve to growth and sexual reproduction in coming year.

    Compensatory growth of Carex scabrirostris in different habitats in alpine meadow
    ZHU Zhi-Hong, XI Bo, LI Ying-Nian, ZANG Yue-Ming, WANG Wen-Juan, LIU Jian-Xiu, GUO Hua
    Chin J Plant Ecol. 2010, 34 (3):  348-358.  doi:10.3773/j.issn.1005-264x.2010.03.012
    Abstract ( 2475 )   Full Text ( 4 )   PDF (462KB) ( 1766 )   Save
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    Aims Compensatory growth is affected by defoliation ratio, water and soil nutrient availability, but it is unclear which factor is most important in the overcompensatory response to herbivores in a particular area. Our objectives were to examine how compensatory growth of Carex scabrirostris varies with different habitats in an alpine Kobresia humilis meadow and determine relative effects of these factors on compensatory growth.

    Methods Our field experiment at the Haibei Research Station of the Chinese Academy of Sciences from April to September 2007 included three habitats (habitat I: pen pasture, grazed × high nutrient availability; habitat II: pass pasture, grazed × low nutrient availability and habitat III: ungrazed pasture, null defoliation ratio × low nutrient availability) with three plots per habitat. In each plot, 12 quadrats (0.5 m × 0.5 m) were divided into two groups: 6 caged and 6 uncaged. For each of these sets of 6 quadrats, 3 quadrats were sampled in mid-June and 3 in mid-August. We used canonical correspondence analysis (CCA) with potential impact factors selected by the forward selection procedure for the compensatory growth of C. scabrirostris ramets to determine the relative effects of defoliation ratio, water and soil nutrient variables on compensatory growth.

    Important findings The compensatory increase in dry weight, cover, density and height of ramets were higher for the habitat I than for habitats II and III. Overcompensation of aboveground biomass per ramet occurred in habitat I and II, whereas undercompensation was found in habitat III. The biomass allocation to growth function per ramet in habitat I was equal to that of III but higher than that of II. Storage allocation was greatest in habitat II, moderate in III, and least in I. Storage allocation was negatively correlated with growth and clonal propagation allocations, and growth allocation was negatively correlated with sexual reproductive allocation. The most important factors that induced compensatory growth were relative growth rate and soil organic matter content in June, followed by nitrogen content in August and defoliation ratio. These results suggest that the ramets in nutrient-rich habitat or in nutrient-poor habitat but having a high storage allocation tend to have overcompensation growth. The nutrient-rich habitat can compensate for the negative effects of herbivores and improve the ability to tolerate herbivores.

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