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Table of Content
    Volume 33 Issue 6
    30 November 2009
      
    Research Articles
    EMISSIONS OF SOIL GREENHOUSE GASES IN RESPONSE TO UNDERSTORY REMOVAL AND CASSIA ALATA ADDITION IN AN EUCALYPTUS UROPHYLLA PLANTATION IN GUANGDONG PROVINCE, CHINA
    LI Hai-Fang, XIA Han-Ping, FU Sheng-Lei, ZHANG Xing-Feng
    Chin J Plan Ecolo. 2009, 33 (6):  1015-1022.  doi:10.3773/j.issn.1005-264x.2009.06.001
    Abstract ( 2036 )   PDF (1386KB) ( 1129 )   Save
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    Aims CO2, CH4 and N2O are important greenhouse gases, and they mainly come from soils in forest ecosystems. Our objective was to analyze the effects of removal of the understory and addition of Cassia alata on soil CO2, CH4 and N2O emissions in Heshan Hilly Land Interdisciplinary Experimental Station, Chinese Academy of Sciences, Guangdong Province, China.
    Methods CO2, CH4 and N2O fluxes in a Eucalyptus urophylla plantation were measured in situ using the static chamber technique from June 2007 to May 2008.
    Important findings CO2 fluxes stayed at a relatively high level during the rainy season and a lower level in the dry season, while CH4 and N2O fluxes varied widely in the rainy season and were stable in the dry season. Peak values of CO2 and CH4 appeared in the rainy season, while the peak value of N2O flux was in the dry season (December). The E. urophylla plantation soil was a sink or source for CH4 while consistently a source for CO2 and N2O. Understory removal and C. alata addition significantly enhanced CO2 (p<0.01) and N2O fluxes (p<0.01), while decreasing or increasing CH4 fluxes under the same treatments. Results indicated that soil temperature, soil moisture, NO3-N and microbial biomass carbon (MBC) might be important variables for soil CO2, CH4 and N2O fluxes.
    EFFECTS OF CO2 ENRICHMENT, HIGH NITROGEN DEPOSITION AND HIGH PRECIPITATION ON A MODEL FOREST ECOSYSTEM IN SOUTHERN CHINA
    DENG Qi, ZHOU Guo-Yi, LIU Ju-Xiu, LIU Shi-Zhong, DUAN Hong-Lang, CHEN Xiao-Mei, ZHANG De-Qiang
    Chin J Plan Ecolo. 2009, 33 (6):  1023-1033.  doi:10.3773/j.issn.1005-264x.2009.06.002
    Abstract ( 2075 )   PDF (953KB) ( 1224 )   Save
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    Aims Responses of soil respiration to global change play an important role in global carbon cycling, but the effects of increasing atmospheric carbon dioxide concentration ([CO2]), nitrogen (N) deposition and precipitation on soil respiration in subtropical China are unclear. Our objective was to test the effects of increased [CO2], N deposition and precipitation on soil respiration and to determine how they influence soil respiration in subtropical China.
    Methods A model forest ecosystem was constructed of six tree species native to South China. The species were exposed to four experimental treatments in open-top chambers beginning March 2005. Three chambers were used for elevated [CO2] (CC), two for high N treatment (NN) and the control (CO) and one for elevated precipitation (HR). The CC treatment was achieved by supplying additional CO2 from a tank until the chambers had a concentration of (700 ± 20) μmol CO2·mol–1. The NN treatment was achieved by spraying seedlings once a week for a total amount of NH4NO3 of 100 kg N·hm–2·a–1. The HR treatment was achieved by weekly irrigation with 100 L water.
    Important findings For two years, soil respiration displayed strong seasonal patterns with higher val-ues observed in the wet season (April to September) and lower values in the dry season (October to March) in the control chambers (CO) and the CC and NN treatments (p<0.001). There was no seasonal difference in the HR treatment (p>0.05). The CC enrichment affected soil respiration significantly (p<0.05), and there were no significant differences in annual CO2 effluxes between CO and the other two treatments. The annual CO2 effluxes reached 4 241.7, 3 400.8, 3 432.0 and 3 308.4 g CO2·m–2·a–1 in the CC, NN, HR and CO treatments, respectively. Soil respiration showed diverse responses between dry and wet seasons under different treatments. Higher soil respiration in the CC and NN treatments occurred in the wet season (p<0.05). In the dry season, soil respiration increased in the HR treatment (p<0.05) and decreased in the NN treatment (p<0.05). We found significant exponential relationships between soil respiration rates and soil temperature and significant linear relationships between soil respiration rates and soil moisture (below 15%).
    LANDSCAPE PATTERN AND DYNAMICS IN A NATURAL TROPICAL FOREST OF BAWANGLING, HAINAN ISLAND, CHINA
    ZHANG Zhi-Dong, ZANG Run-Guo
    Chin J Plan Ecolo. 2009, 33 (6):  1034-1043.  doi:10.3773/j.issn.1005-264x.2009.06.003
    Abstract ( 1952 )   PDF (866KB) ( 1136 )   Save
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    Aims Effective protection of tropical forest requires understanding changes in landscape pattern during the forest recovery process. Our aims were to 1) examine forest recovery dynamics and landscape pattern change and 2) explore the impact of proximity of mature forest fragments on secon-dary succession.
    Methods We investigated 135 sample plots in a natural tropical forest landscape of Bawangling, Hainan Island, China. Three Landsat Thematic Mapper (TM) imageries from 1986, 1998 and 2002 were used along with a grid-based approach and statistical methods to analyze forest recovery dynamics and landscape pattern change. The spatial relationship between mature forest fragments and different suc-cessional stage forests was analyzed by buffer analysis and Chi-square analysis.
    Important findings There were four forest patch types based on stage of recovery. Between 1986 and 1998, the proportion of all patch types except late-successional forest changed significantly; however, between 1998 and 2002 most of the patch types were little changed, indicating that deforestation de-creased. From 1998 to 2002, the number of patches and edge density increased and mean patch size and core area decreased in most patch types, indicating that fragmentation of the study region increased. The distribution of secondary forest was significantly correlated with proximity to late-successional forest, because the proportion of young secondary forest gradually increased with greater distance from late-successional forest. This suggests that proximity of late-successional forest facilitates forest re-covery following human disturbance.
    CARBON CYCLE MODELING OF A BROAD-LEAVED KOREAN PINE FOREST IN CHANGBAI MOUNTAIN OF CHINA USING THE MODEL-DATA FUSION APPROACH
    ZHANG Li, YU Gui-Rui, LUO Yiqi, HE Hong-Lin, ZHANG Lei-Ming
    Chin J Plan Ecolo. 2009, 33 (6):  1044-1055.  doi:10.3773/j.issn.1005-264x.2009.06.004
    Abstract ( 1906 )   PDF (882KB) ( 1536 )   Save
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    Aims Our objective was to use multiple terrestrial carbon observations to improve existing terrestrial ecosystem models.
    Methods We conducted a Bayesian probabilistic inversion to estimate the key parameter (i.e., carbon residence time) of a terrestrial ecosystem model (TECO) by using biometric and eddy covariance flux data measured at a temperate broad-leaved Korean pine forest in Changbai Mountain (CBS) of China from 2003 to 2005. We then estimated carbon stocks, carbon fluxes and uncertainties with posterior estimates of parameters. Biometric measurements consisted of foliage biomass, fine root biomass, woody biomass, litterfall, soil organic matter (SOM) and soil respiration.
    Important findings Residence times of carbon for most pools can be constrained by eddy covariance flux and biometric measurements, except for the passive soil organic matter pool. Estimated residence times of C ranged from 2 to 6 months for litter and microbial biomass pools, 1 to 2 years for foliage and fine root biomass, 8 to 16 years for slow SOM pool and 77–109 and 409–1 879 years for woody biomass and passive SOM pools, respectively. Model results showed that the prediction uncertainties of carbon stocks and accumulated carbon fluxes increased with time. When air temperature increased 10% and 20%, annual gross primary productivity (GPP) increased 6.5% and 9.9%, but annual net ecosystem productivity (NEP) changed with soil temperature. If soil temperature is constant, annual NEP increased 11.4%–21.9% and 17.6%–33.1%, while if soil temperature increased 10% and 20%, annual NEP decreased to a level that was lower than that under ambient temperature. Given the same climate condition and seasonal variation for leaf area index during 2003–2005, annual NEP and soil respiration in 2020 would be 163±12 and 721±14 g C·m–2·a–1. Markov Chain Monte Carlo method is an effective way to estimate model parameters and to evaluate model prediction uncertainties. However, more studies are needed on a) estimation of residence time of C for passive soil organic matter, b) uncertainty analysis of input data and model structure and c) model-data fusion methods so as to improve the prediction accu-racy of terrestrial ecosystem models.
    DEM-BASED MODELING OF THE IMPACT OF VEGETATION RESTORATION ON ANNUAL STREAMFLOW IN THE LOESS PLATEAU OF CHINA
    ZHANG Xiao-Ping, ZHANG Lu, LI Rui, YANG Qin-Ke
    Chin J Plan Ecolo. 2009, 33 (6):  1056-1064.  doi:10.3773/j.issn.1005-264x.2009.06.005
    Abstract ( 1955 )   PDF (834KB) ( 1256 )   Save
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    Aims Vegetation is the fundamental measure to control erosion in the Loess Plateau. It is believed that forests use more water than grasslands and hence reduce average annual streamflow; however, the spatial distribution of vegetation restoration and its impacts on annual streamflow, especially on the regional scale, are poorly known. Our objectives were to map the vegetation suitability in the Hekou-Longmen (Short with He-Long) region of the middle reaches of Yellow River and assess the impact of afforestation on streamflow based on two plantation scenarios.
    Methods We assumed 1) the combined effects of bio-climatic zones on regional scale and local land-form determined vegetation suitability, 2) higher precipitation is more suitable for plantations and 3) the extent of soil moisture availability defined by three local factors (slope, aspect and slope profile) depends on precipitation. We defined high, moderate and low vegetation suitability classes and developed a vegetation suitability map for the region using 100 m Digital Elevation Model (DEM) and the above assumptions. Plantation scenario 1 was developed using only the highly suitable area, and scenario 2 comprised both the highly and moderately suitable areas. The locally calibrated average annual water balance model of Zhang et al. (2001) was used to assess the impacts of afforestation on annual stream-flow in the study area.
    Important findings The highly suitable area for plantation covers 6.6×103 km2, and the moderately suitable area covers 4.8×103 km2, representing 5.8% and 4.3% of the total area, respectively. The planta-tion area made up 0–45% of individual catchments. The area suitable for plantation became increasingly patchy and sparse from south to north. Under current land cover status, average annual streamflow in the region was estimated to be 38.07×108 m3or 33.8 mm. Under scenario 1, average annual streamflow would be reduced by 2.12×108 m3or 1.9 mm (5.5%). Under scenario 2, the modeled streamflow reduc-tion is 3.49×108 m3or 3.1 mm (9.2%). Corresponding to the spatial distribution of plantation, the reduc-tion in streamflow is spatially variable. The rate of streamflow reduction varies from 0 to 36%. Minimum reduction occurred in the northwestern part of the region, where there is little area suitable for plantation development. Maximum reduction of 36% occurred in the southeastern part of the region where precipitation is highest.
    EFFECTS OF GRAZING ON FOLIAGE BIOMASS ALLOCATION OF GRASS-LAND COMMUNITIES IN XILIN RIVER BASIN, INNER MONGOLIA
    REN Hai-Yan, ZHENG Shu-Xia, BAI Yong-Fei
    Chin J Plan Ecolo. 2009, 33 (6):  1065-1074.  doi:10.3773/j.issn.1005-264x.2009.06.006
    Abstract ( 2295 )   PDF (592KB) ( 1503 )   Save
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    Aims Our objective is to determine whether 1) characteristics of gazing-induced individual miniaturization differ among plant species and across grassland communities, 2) miniaturized plants have detectable changes in resource allocation, and 3) grazing-induced changes in plant resource alloca-tion affect ecosystem functioning at the plant community level.
    Methods Resource allocation of 144 common species from grassland communities, i.e. Carex appendiculata meadow, Stipa baicalensis meadow steppe, Leymus chinensis typical steppe, Stipa grandis typical steppe, Caragana microphylla typical steppe, and Artemisia frigida typical steppe, were investi-gated along a soil moisture gradient in the Xilin River Basin, Inner Mongolia. We measured morpho-logical traits, including reproductive height, vegetative height, canopy coverage, leaf biomass, stem biomass, stem:leaf ratio, and total biomass of common species at the individual and community levels from paired ungrazed and grazed plots.
    Important findings Long-term grazing across the six grassland communities significantly decreased average plant morphological traits such as reproductive height, vegetative height, canopy coverage, leaf biomass, stem biomass, stem:leaf ratio, and total individual biomass in 55%–94% of the common plant species, indicating that individuals tend to miniaturize in response to overgrazing. At the community level, grazing also decreased stem, leaf, and total aboveground biomass. Plant species increased their biomass allocation to leaves, but decreased biomass allocation to stems in grazed plots as compared to the ungrazed plots. This suggests that the increase in resource allocation to photosynthetic organs (e.g., leaves) is likely an important strategy of plants adapting to long-term grazing. In contrast, light grazing increased plant biomass production at both individual and community levels at the meadow steppe. In addition, soil moisture may have important effects on plant resource allocation, with high biomass allo-cation to stems in wet habitats.
    COMPARISON OF STORAGE OF COARSE WOODY DEBRIS BETWEEN HUZHONG FOREST BUREAU AND HUZHONG NATURAL RESERVE IN DA HINGGAN MOUNTAINS, CHINA
    LIU Zhi-Hua, CHANG Yu, HU Yuan-Man, LI Yue-Hui, WANG Jin-Hai, JING Guo-Zhi, ZHANG Hong-Xin, ZHANG Chang-Meng
    Chin J Plan Ecolo. 2009, 33 (6):  1075-1083.  doi:10.3773/j.issn.1005-264x.2009.06.007
    Abstract ( 1848 )   PDF (1521KB) ( 1121 )   Save
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    Aims Coarse woody debris (CWD) plays an important role in maintaining biodiversity, providing critical habitat for organisms and cycling of carbon and nitrogen in forest systems. Our objective was to understand the effects of anthropogenic disturbance on CWD in Da Hinggan Mountains as the key to forest health and sustainable forest management.
    Methods We compared CWD storage using a line-intercept method in Huzhong Forest Bureau, which represented forest affected by anthropogenic disturbance, with Huzhong Natural Reserve, which repre-sented primary forest unaffected by anthropogenic disturbance, of Da Hinggan Mountains.
    Important findings Storage of CWD varied between 5.92~43.53 m3·hm–2 in Huzhong Natural Reserve and 12.70~47.59 m3·hm–2 in Huzhong Forest Bureau. Anthropogenic disturbance had greater effects on mixed and coniferous forest than broadleaf forest. More CWD occurred in mixed forest and less CWD in coniferous forest, and the proportion of the advanced decay class CWD increased and snags de-creased with anthropogenic disturbance. The storage of CWD in managed forest (8.20–25.60m3·hm–2) is less than that in virgin forest (18.70–36.99 m3·hm–2). Residue from harvesting should be maintained to retain the natural forest characteristics of CWD.
    DETECTING EFFECT OF PHYLOGENETIC DIVERSITY ON SEEDLING MORTALITY IN AN EVERGREEN BROAD-LEAVED FOREST IN CHINA
    CHEN Ying
    Chin J Plan Ecolo. 2009, 33 (6):  1084-1089.  doi:10.3773/j.issn.1005-264x.2009.06.008
    Abstract ( 1906 )   PDF (499KB) ( 1714 )   Save
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    Aims Negative density dependence plays an important role in maintaining forest biodiversity. Ecologists found this mechanism operates not only between conspecifics but also between closely related heterospecifics. Our objective was to determine whether phylogenetic diversity affects seedling mortality at different scales.
    Methods We used net relatedness index (NRI) and nearest taxon index (NTI) to represent phyloge-netic diversity and employed logistic regression modeling. We analyzed the relationship between seed-ling mortality and phylogenetic diversity using the seedling dynamic data from six seedling censuses of 507 seedling plots at Gutianshan Nature Reserve during May 2006 and November 2007.
    Important findings We found that higher density of conspecifics resulted in higher seedling mortality, and phylogenetic diversity was responsible for seedling mortality when seedling density was high (>3.46 individuals·m–2).
    COMMUNITY STRUCTURE IN DIFFERENT SUCCESSIONAL STAGES IN NORTH TEMPERATE FORESTS OF CHANGBAI MOUNTAINS, CHINA
    ZHANG Chun-Yu, ZHAO Xiu-Hai, ZHAO Ya-Zhou
    Chin J Plan Ecolo. 2009, 33 (6):  1090-1100.  doi:10.3773/j.issn.1005-264x.2009.06.009
    Abstract ( 2059 )   PDF (639KB) ( 1889 )   Save
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    Aims The Changbai Mountains had a large area of undisturbed temperate old-growth forest that was partly destroyed by large-scale industrial logging at the turn of the 20th century and replaced by secondary forests and plantations. Our objective was to further understand ecosystem development, community composition and structure, and spatial distribution of major tree populations.
    Methods Three long-term 5.2 hm2 forest plots were established in secondary Populus davidiana-Betula platyphylla forest (PBF), secondary conifer and broadleaved mixed forest (SCBMF) and Tilia amurensis-Pinus koraiensis mixed forest (TPMF) in the Changbai Mountains following the protocols of the Center for Tropical Forest Science forest dynamic plot. We tagged and recorded the species, diameter at breast height (DBH), height and crown diameter of all live and dead trees with DBH >1 cm. We determined the spatial distribution of five dominant canopy tree species by pair-correlation g(r) function and performed variation partitioning analysis to estimate the environmental effect on spatial distribution.
    Important findings We recorded 20 949, 14 725 and 12 062 live individuals and basal areas of 24.74, 32.07 and 56.64 m2·hm–2 in PBF, SCBMF and TPMF, respectively. Tilia amurensis, with the overall highest importance value and basal area, was the major dominant tree species in SCBMF, P. davidiana and B. platyphylla dominated PBF and P. koraiensis dominated TPMF. In the secondary forests BPF and SCBMF, the size-class distribution of Pinus koraiensis, Acer mono, Abies nephrolepis, Picea jezoensis and Tilia amurensis showed the reverse J-shape form, whereas P. koraiensis and T. amurensis showed normal distributions in TPMF. Paired-correlation g(r) function showed that the main tree species had aggregated distributions, and the aggregation intensity decreased with the increasing distances. Environment variables had a strong effect on tree distribution, but the interpretation power of environment variables was very low in TPMF.
    VEGETATION CARRYING CAPACITY BASED ON SOIL WATER ON TYPICAL SLOPES IN THE DIEDIEGOU SMALL WATERSHED OF LIUPAN MOUN-TAINS, NORTHWESTERN CHINA
    LIU Jian-Li, WANG Yan-Hui, YU Peng-Tao, CHENG Li-Li, XIONG Wei, XU Li-Hong, Du A-Peng
    Chin J Plan Ecolo. 2009, 33 (6):  1101-1111.  doi:10.3773/j.issn.1005-264x.2009.06.010
    Abstract ( 1883 )   PDF (1425KB) ( 1137 )   Save
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    Aims Soil water is the main limiting factor for vegetation, and it mainly comes from precipitation in the Diediegou small watershed in the Liupan Mountains, northwestern China, where the structure of slope vegetation is usually closely related with the amount of precipitation. Our objectives were to develop a method for estimating vegetation carrying capacity (VCC) on sites based on water balance and to evaluate variation of VCC along typical slopes, for guiding the restoration and management of vegetation on similar slopes.
    Methods We established nine plots along two typical slopes of natural grassland and larch (Larix principis-rupprechti) plantation, measured leaf area index (LAI) every 15 days and continuously monitored all water fluxes and soil water dynamics. After analyzing plot water balance, we determined the relationships among evapotranspiration (ET), LAI and precipitation to estimate VCC based on growing season precipitation and calculated the variation of VCC along slopes.
    Important findings Our mathematical models for determining VCC (expressed as the maximal LAI) based on precipitation amount (P, mm) in growing season (April–October) were LAItree=exp ((0.773 1×P–186.12)/146.46) for the larch stand on the shady slope and LAIgrass=exp ((0.511 2× P–345.93)/227.89) for the grassland on the sunny slope. The VCC of larch stands on the shady slope increased from upper slope (1.45) to middle slope (4.83) and then stabilized between 3.0 and 3.3. For grassland on the sunny slope, VCC increased from upper slope (0.37) to middle slope (0.46) and then stabilized between 0.41 and 0.47. Measured values of LAI were close to those of simulated VCC, sup-porting the rationality of our method and the result. Using LAI as an index expressing VCC, which is mainly determined by soil water in dryland regions, is a new method for calculating VCC for slopes where precipitation water is redistributed in the forms of runoff and interflow.
    PHOTOSYNTHETIC PHYSIOLOGICAL RESPONSES OF GLYCYRRHIZA URALENSIS UNDER DIFFERENT WATER AND NUTRIENT SUPPLIES IN KUBUQI DESERT, CHINA
    LI Yang, HUANG Jian-Hui
    Chin J Plan Ecolo. 2009, 33 (6):  1112-1124.  doi:10.3773/j.issn.1005-264x.2009.06.011
    Abstract ( 1786 )   PDF (1314KB) ( 1111 )   Save
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    Aims Changes in precipitation pattern and increases in nitrogen deposition have been predicted in previous studies of global change, and these may significantly affect plant growth in terrestrial ecosystems and the availability of resources such as water and nutrients for plant use. Our objective was to determine photo-physiological responses and adaptation of licorice (Glycyrrhiza uralensis), a domi-nant legume species in the Kubuqi Desert, to different water and nutrient (N, P) supplies.
    Methods Using a completely randomized design, we subjected second-year licorice seedlings to water treatment at four supplement levels (3/8, 1/2, 1, and 2 times mean annual precipitation of the study area) and four nutrient treatments (CK, N: 83 mg N·kg–1 soil, P: 92 mg P·kg–1 soil, and NP: 83 mg N·kg–1+92 mg P·kg–1 soil) in 2005. We also determined diurnal changes of photo-physiological characteristics and light response curves.
    Important findings Water supply and nutrient addition significantly affected licorice physiological characteristics. Water stress decreased gas exchange characteristics, such as net photosynthesis rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr), and down-regulated several A-PAR relationship curve parameters, such as maximum net photosynthetic rate (Pmax) and apparent quantum efficiency (AQE). The major control of photosynthesis under severe water shortage (W1) varied between stomatal and non-stomatal limitation. Therefore, the second-year licorice seedlings performed a quick physio-logical response and corresponding regulation to water supply. Nutrient addition could increase Pn, es-pecially under high-water supply, and phosphorus addition could also stimulate Pmax and light saturation point (LSP) and diminish light compensation point (LCP) under extremely low water supply. Shortage of water supply or nutrient addition combined with high water supply (W4) would decrease photosyn-thetic water use efficiency (PWUE). Our results suggest that water supply is the primary limiting factor and nutrient addition is secondary for licorice photosynthesis in this desert area.
    EVIDENCE AND ECOLOGICAL EFFECTS OF HYDRAULIC LIFT IN POPULUS EUPHRATICA
    HAO Xing-Ming, CHEN Ya-Ning, LI Wei-Hong, Guo Bin, ZHAO Rui-Feng
    Chin J Plan Ecolo. 2009, 33 (6):  1125-1131.  doi:10.3773/j.issn.1005-264x.2009.06.012
    Abstract ( 1878 )   PDF (1070KB) ( 1584 )   Save
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    Aims In the Tarim River Basin of China, desert riparian forest vegetation grows despite the stresses of high temperature and aridity. The species have deep roots that absorb soil water, but a more important reason may be the hydraulic lift (HL) of species. Our aims are to explore whether HL exists in desert riparian vegetation and to determine its ecological impacts.
    Methods We studied the HL of Populus euphratica, an important species of desert riparian forest, in September 2008. We used heat ration method (HRM) sap-flow monitoring sensors to measure sap ve-locity in roots of three trees during four days. Meteorological factors, including wind speed, air relative humidity, leaf temperature and surface temperature, were monitored by a recording weather station. We concurrently sampled and analyzed soil water content by the drying method at six soil depths.
    Important findings The sap velocity of tap roots was positive day and night. In contrast, sap flows of lateral roots reversed at night. Soil water content in the subsoil was higher than topsoil in 0–120 cm soil depth and increased with reversed sap flow of lateral roots at night, especially in the 60–120 cm soil depth (soil water content was 28%–38% greater at 4:00 than that at 16:00. Leaf surface vapor pressure deficit can critically affect sap velocity in lateral roots. Hydraulic redistribution has commonly been as-sociated with arid or strongly seasonal environments; our findings prove it also occurs in an extremely arid region of middle Asia.
    GROWTH AND BIOMASS ALLOCATION DYNAMICS OF ARTEMISIA ORDOSICA IN SAND-FIXING VEGETATION OF THE TENGGER DESERT OF CHINA
    FENG Li, ZHANG Jing-Guang, ZHANG Zhi-Shan, GUO Qun, LI Xin-Rong
    Chin J Plan Ecolo. 2009, 33 (6):  1132-1139.  doi:10.3773/j.issn.1005-264x.2009.06.013
    Abstract ( 1789 )   PDF (593KB) ( 1276 )   Save
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    Aims Resource allocation pattern is an important trait of plant ecological adaptive strategy. The composite sub-shrub Artemisia ordosica is widely distributed in the sandy land of northern China and is an important sand-stabilizing plant. However, its growth dynamics and resource allocation patterns are poorly known. Our objectives were to determine: 1) the growth dynamics of vegetative and reproductive organs and the biomass allocation pattern in different growth periods; 2) the relationship between reproductive and vegetative growth and 3) variations of biomass allocation pattern with age of sand-fixing vegetation.
    Methods A field experiment was conducted on re-vegetated areas in Shapotou, located at southeastern fringe of Tengger Desert, from April to November 2007. Twenty-five A. ordosica were sampled monthly in sand-fixing vegetation planted in 1956, 1964, 1981, 1987 and 1991 to measure the number, size and biomass of vegetative organs and reproductive organs such as leaves, vegetative shoots, flow-ering shoots, capitula and seeds.
    Important findings In different growth periods, there were different growth rates and proportion of photosynthate allocation to organs. So the energy accumulation center and growth center vary with growth period. The vegetative growth, reproductive output and size of panicle in 2007 were significantly greater than those in the year when precipitation was less than half that in 2007, while no significant differences were found in reproductive allocation and size of capitula between these years. The in-dividuals with greater vegetative biomass were also characterized by higher reproductive output, but the vegetative and reproductive growth were unsynchronized with different increment speed, which indi-cated that there was a trade-off between reproduction and vegetative growth. Annual biomass, reproductive output and reproductive allocation showed a trend of decrease with time extension of the sand-fixing project, but no statistically significant differences of the three indices were found among these five vegetation areas with different ages.
    EFFECTS OF NITROGEN AND PHOSPHOROUS LEVELS ON GROWTH AND PHOTOSYNTHETIC TRAITS OF GRACILARIA LEMANEIFORMIS (RHODOPHYTA)
    LI Feng, ZOU Ding-Hui, LIU Zhao-Pu, ZHAO Geng-Mao, CHENG Li-Wei, ZHU Xi-Feng, CHEN Wei-Zhou
    Chin J Plan Ecolo. 2009, 33 (6):  1140-1147.  doi:10.3773/j.issn.1005-264x.2009.06.014
    Abstract ( 1939 )   PDF (907KB) ( 1424 )   Save
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    Aim Our objective was to investigate the impacts of different nutrient levels on the physiology of Gracilaria lemaneiformis to evaluate the relationship between this mariculture species and costal envi-ronment.
    Methods Thalli of Gracilaria lemaneiformis were cultured for 15 days under four different nutrient conditions (low N and low P, low N and high P, high N and low P, and high N and high P) to examine the possible effects of the availability of different nutrients on growth and photosynthesis in this alga.
    Important findings Growth of G. lemaneiformis was enhanced with the low N and high P treatment, high N and low P treatment, and high N and high P treatment, compared to low N and low P treatment. The highest relative growth rate (RGR) and biomass were observed under high N and high P treatment. Gracilaria lemaneiformis was capable of using HCO3 as a source of exogenous inorganic carbon (Ci) for its photosynthesis, and the ability was increased at the above three nutrient conditions. Both carbon-saturated photosynthetic rate and apparent half saturation constant under high N and high P treat-ment were significant higher than those under low N and low P treatment by 118% and 48.71%, respectively. Photochemical efficiency of G. lemaneiformis was stimulated with low N and high P treatment, but was inhibited at the two high N treatments. Thus, the rates of growth and photosynthesis were the highest, but the photochemical efficiency was the lowest in G. lemaneiformis grown under high N and high P treatment.
    LIGHT ENERGY UTILIZATION AND CHLOROPHYLL FLUORESCENCE IN TWO CROSSBREED POPLARS
    YOU Xin, GONG Ji-Rui, GE Zhi-Wei, DUAN Qing-Wei, AN Ran, CHEN Dong-Hua, ZHANG Xin-Shi
    Chin J Plan Ecolo. 2009, 33 (6):  1148-1155.  doi:10.3773/j.issn.1005-264x.2009.06.015
    Abstract ( 1876 )   PDF (517KB) ( 1223 )   Save
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    Aims Our objective was to study two widely planted hybrid poplars, Populus deltaids ‘cv-64’ (P64) and P. simonii canaden × P. russkii-9 (Jia), to explore their growth mechanisms and the solar energy utilization by photosystem II (PSII) antennae to thermal energy dissipation and photosynthetic electron transport characteristics during long-term adaptation to the ambient environment.
    Methods We studied energy utilization by computing chlorophyll fluorescence parameters and photo-synthesis. Plants were grown at the Plain Forest Farm Nursery of the State Forestry Bureau of Ili Autonomous Prefecture in China’s Xinjiang region.
    Important findings The diurnal changes of net photosynthesis (Pn) were bimodal and had a 20.1% gap under high photon flux density (PFD). The actual efficiency of open PSII centers (ΦPSII) were all of the “U” type, and their average values were equal. The ΦPSII of P64 and Jia reached the minimum value at 16:30 and 14:30, respectively. The closure value had one wave hollow at 14:30, and there was no significant difference (p>0.05) in whole-day average values. The non-photochemical quenching co-efficients (NPQ) all achieved the maximum value at 16:30. Jia’s NPQ maximum was less than that of P64, and the whole-day NPQ difference reached 31.7%. The estimated rates of photochemistry (E.P) and non-photochemistry (E.D) showed that under the lower PFD the poplars used more than 50% of the absorbed solar energy for the photochemical quenching, and under high PFD the absorbed solar energy for P64 for the photochemical quenching is greater than the proportion for Jia, while the absorbed solar energy for P64 for heat dissipation is less than the proportion for Jia. The E.P had no difference and reached the maximum estimated value when its E.D reached the maximum. P64 tended to use more absorbed solar energy for photochemical quenching, but Jia tended to use more solar energy for non-photochemical quenching. The cumulative values and average values of the Pn for Jia were much larger than values for P64, but the absorbed solar energy of P64 is greater than the proportion of Jia for the photochemical quenching. These results prove that it is inadequate to calculate the absorbed energy only by the chloroplast fluorescent characteristics of light received.
    POLLINATION ECOLOGY OF GENTIANA LAWRENCEI VAR. FARRERI, A LATE-FLOWERING QINGHAI-TIBET PLATEAU SPECIES
    HOU Qin-Zheng, DUAN Yuan-Wen, SI Qing-Wen, YANG Hui-Ling
    Chin J Plan Ecolo. 2009, 33 (6):  1156-1164.  doi:10.3773/j.issn.1005-264x.2009.06.016
    Abstract ( 1830 )   PDF (818KB) ( 1019 )   Save
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    Aims Gentiana lawrencei var. farreri (Gentianaceae), a late-autumn or early-winter flowering alpine perennial, is distributed mainly in the northeastern Qinghai-Tibetan Plateau (QTP). The environment of the QTP is harsh because temperature is low and insects are scarce. Our aim is to examine the pollination ecology of G. lawrencei and its adaptive relationship with the environment.
    Methods The pollination ecology of G. lawrencei was documented for three consecutive years in northeastern QTP. The breeding system was tested and floral visitors were observed during the flower life span. Flower longevity was recorded and stigma receptivity was tested by the seed-set ratio of dif-ferent days in which the stigma was presented.
    Important findings The seed-set of G. lawrencei under natural conditions was extremely low because of pollen-limitation. Combined characters of herkogamy and incomplete dichogamy indicate that polli-nators are needed for complete pollination. Some individuals of G. lawrencei could produce seeds under bagging without emasculation, and it may be from selfing caused by thrips and ants. Bombus kashmirensis and B. sushikini are effective pollinators of G. lawrencei, but the frequencies of visits are extremely low (0.006 and 0.005 time·flower–1·h–1, respectively). Floral longevity and stigma receptivity are relatively long compared with other Gentianaceae species, and these increase the probability of pol-lination chances under low temperature and low pollinator conditions. The combination of self- and cross-pollination, as well as the prolonged floral longevity and stigma receptivity, may be the main reason for the survivorship of G. lawrencei.

    NODULE CHARACTERISTICS OF THREE-YEAR-OLD CARAGANA MICROPHYLLA AND THEIR RESPONSES TO ENVIRONMENTAL CHANGES IN AN INNER MONGOLIA GRASSLAND
    ZHANG Can-Juan, WU Dong-Xiu, ZHANG Lin, ZHAN Xiao-Yun, ZHOU Shuang-Xi, YANG Yun-Xia
    Chin J Plan Ecolo. 2009, 33 (6):  1165-1176.  doi:10.3773/j.issn.1005-264x.2009.06.017
    Abstract ( 2189 )   PDF (493KB) ( 1055 )   Save
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    Aims Caragana microphylla widely spreads in Inner Mongolia grasslands as a dominant shrubby legume. Its nodule growth has been poorly addressed. Our objective is to examine nodule characteristics and their responses to different environmental factors to provide insights into their nitrogen fixing and nitrogen cycling processes under future changing environments.
    Methods We conducted a field experiment in 2008 using open-top chambers at the Inner Mongolia Grassland Ecosystem Research Station of Chinese Academy of Sciences. We examined the number, weight and length of nodules of three-year-old C. microphylla individuals and their responses to nitrogen addition, drought, water addition and elevated atmospheric CO2 concentration.
    Important findings Nodules were mainly distributed in lateral roots, and most had buff or brown color. Nodule shapes were diverse, being pyriform, globular, claviform, fusiform, and Y shaped. Root growth and nodule growth were significantly inhibited under the nitrogen addition treatment, resulting in roots being whitened and most nodules dead and black-brown. Drought depressed root nodulation, with mean length of nodules decreased significantly by 50.4% compared with that under normal water supply. Water addition stimulated root growth and nodule growth. Roots nodulated best under the combined treatment of water addition, elevated CO2 and non-nitrogen addition, with maximum mean length and weight of individual nodules and the maximum nodule weight per plant. Nodules in fibers relatively increased with increasing water supply. Nodule growth did not significantly respond to elevated CO2. Nodule number is more sensitive to environmental changes than nodule size, there are significant nitro-gen × water interactions on nodule number and weight per plant and the effects of three environmental factors on nodule growth are different. The negative effect of nitrogen is larger than the positive effects of water and elevated CO2. It is inferred that water is the major factor affecting the infection of rhizobia and the generation of nodules in this semiarid grassland ecosystem.
    RESPONSE OF RADIAL GROWTH TO NEIGHBORING COMPETITION AND CLIMATE FACTORS IN TAXUS CUSPIDATA
    ZHANG Chun-Yu, GAO Lu-Shuang, ZHAO Ya-Zhou, JIA Yu-Zhen, LI Jin-Xin, ZHAO Xiu-Hai
    Chin J Plan Ecolo. 2009, 33 (6):  1177-1183.  doi:10.3773/j.issn.1005-264x.2009.06.018
    Abstract ( 1893 )   PDF (1227KB) ( 1252 )   Save
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    Aims Our objective was to address the impacts of sex, tree size, neighboring competition and climate factors on radial growth in Taxus cuspidata.
    Methods An integrative dendroclimatic approach was used to quantify radial growth and relate its response to climate factors.
    Important findings Sex and tree size exhibited significant effects on radial growth in Taxus cuspidata. Radial growth rate was significantly larger in males than in females (p=0.023) and was negatively related to neighboring competition in both sexes. Female trees were affected more negatively by neighboring competition than males (p<0.05). Dendroclimatic analysis indicated different responses to climate factors for males and females. Radial growth in females was negatively related to mean temperature in August and October of the previous year, but no significant associations to mean temperature were found in males. Radial growth in females was associated negatively with precipitation in the current January, and that of males was associated negatively with precipitation in the current August.
    DIURNAL CO2 EXCHANGE RATES OF THE AQUATIC CRASSULACEAN ACID METABOLISM PLANT ISOETES SINENSIS PALMER AT DIFFERENT ALKA-LINITIES
    GU Shu-Ping, YIN Li-Yan, LI Jie-Lin, LI Wei
    Chin J Plan Ecolo. 2009, 33 (6):  1184-1190.  doi:10.3773/j.issn.1005-264x.2009.06.019
    Abstract ( 1945 )   PDF (484KB) ( 1039 )   Save
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    Aims Isoetes sinensis Palmer, an endangered aquatic plant in China, possesses a CAM (Crassulacean acid metabolism) photosynthetic pathway in its submerged leaves. Our objectives were to investigate diurnal CO2 exchange characteristics of submerged leaves and to examine if I. sinensis was capable of net CO2 uptake in the dark, which was considered evidence of the CAM pathway in aquatic plants by Keeley (1998), and determine if diurnal CO2 exchange rates were influenced by alkalinity. Results may contribute to conservation of this endangered plant by determining if high alkalinity of water sources limited population sizes.
    Methods We used the pH-drift technique to analyze CT (total carbon) and CO2 uptake at two alkalin-ities in light and dark conditions. Photosynthetic CT/CO2 response curves were measured at 25 °C and 210 μmol·m–2·s–1 and in a solution designed by Smart and Barko (1985) in which concentrations of NaHCO3 and KHCO3 were varied to supply different alkalinities. Leaves were placed in a small glass chamber, each containing a known volume of the solution which was stirred by a magnetic stirrer at the bottom. The pH/unit time was recorded by a pH electrode that had been calibrated at the beginning and the end of each experiment, the alkalinities of the solution was measured by Gran titration (Talling, 1973) to determine if alkalinity was constant during each experiment. Plant material was weighed after drying overnight at 80 °C. We calculated the concentration of free CO2 and total carbon based on alka-linity, pH, conductivity and temperature according to Mackereth et al. (1978). With the calculated con-centration of CT (or CO2), unit time, chamber volume and amount of plant material present, a photosynthesis or net CO2 exchange rate was obtained. For each alkalinity, the CO2 exchange rate was then plot-ted against the mean concentration of CO2. A covariance approach was used to check if the CO2 exchange significantly differed at two alkalinities.
    Important findings Submerged leaves were capable of net CO2 uptake in both light and dark condi-tions. The CO2 uptake rate was a function of the concentration of CO2 in the medium. The CO2 uptake in dark was significantly influenced by alkalinity of the medium. Alkalinity does not seem to be a sig-nificant factor in reducing the distribution and success of this aquatic species.
    ISOLATION AND IDENTIFICATION OF ALLELOCHEMICALS FROM REHMANNIA GLUTINOSA THAT AFFECT SESAMUM INDICUM
    WANG Ming-Dao, CHEN Hong-Ge, LIU Xin-Yu, GAO Yu-Qian, WU Kun, JIA Xin-Cheng
    Chin J Plan Ecolo. 2009, 33 (6):  1191-1198.  doi:10.3773/j.issn.1005-264x.2009.06.020
    Abstract ( 2133 )   PDF (734KB) ( 1435 )   Save
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    Aims Our objective was to explore why Sesamum indicum yield declined severely when planted after Rehmannia glutinosa in crop rotation.
    Methods We used extraction, silica gel column chromatography, gas chromatography mass spec-trometry and bioassay to isolate and identify allelochemicals from R. glutinosa that affect S. indicum. Bioassays were conducted with extractions from different parts of R. glutinosa.
    Important findings Leaf parts had high allelochemical content. Ethyl acetate phase extraction con-tained most allelochemicals. Active elution Fr7 was obtained by silica gel column chromatography. Allelochemicals lauric acid and 2,6-Ditertbutyl phenol were isolated and identified by use of gas chromatography mass spectrometry. R. glutinosa and S. indicum both have serious continuous cropping obstacles. Allelochemicals affecting S. indicum are different from toxic materials of R. glutinosa. Additional research is needed to further explore interactions of allelochemicals with soil and effects on S. indicum and on the possibility of reducing the effect of R. glutinosa on S. indicum.
    EFFECTS OF POTASSIUM ADDITION AND WATER SUPPLY ON XYLEM EMBOLISM IN ACER TRUNCATUM AND LIGUSTRUM LUCIDUM
    HUANG Ju-Ying, YU Hai-Long, ZHANG Shuo-Xin
    Chin J Plan Ecolo. 2009, 33 (6):  1199-1207.  doi:10.3773/j.issn.1005-264x.2009.06.021
    Abstract ( 1963 )   PDF (748KB) ( 809 )   Save
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    Aims Xylem embolism is a physiological response of tree species to adverse environmental factors, such as water deficit. Potassium plays an important role in plant ability to resist drought. Our objective was to clarify how xylem embolism respond to potassium addition.
    Methods Tree species, Acer truncatum and Ligustrum lucidum were chosen to study the response of xylem embolism, which was measured as the percentage loss of hydraulic conductivity (PLC), to potas-sium addition under drought-stressed and well-watered treatments (soil water content of 30%–40% and 70%–80% of field moisture capacity, respectively).
    Important findings For both species, PLC was higher at 12:30 than at 6:30 and 18:30, while leaf water potential (WP) showed the opposite trend. Potassium addition raised PLC significantly for both species, and the plants with the highest potassium supply generally had the highest PLC. Potassium addition greatly decreased WP of the plants subjected to water deficit. Between the two species, A. truncatum had higher PLC and lower WP. This study suggests that increase in PLC by potassium-addition may result from potassium’s effect on water potential and from its controls on stomata movement, cell osmosis, etc.
    Review
    A REVIEW OF RESPONSES OF LITTER DECOMPOSITION IN TERRESTRIAL ECOSYSTEMS TO GLOBAL WARMING
    XU Zhen-Feng, YIN Hua-Jun, ZHAO Chun-Zhang, CAO Gang, WAN Ming-Li, LIU Qing
    Chin J Plan Ecolo. 2009, 33 (6):  1208-1219.  doi:10.3773/j.issn.1005-264x.2009.06.022
    Abstract ( 2492 )   PDF (409KB) ( 1949 )   Save
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    Litter decomposition in terrestrial ecosystems, an important process in the global carbon budget, is mainly controlled by climate, litter quality and soil organisms. Scientists generally think that global warming could have profound and complicated effects on litter decomposition in terrestrial ecosystems. In this review, we summarized results from microcosm studies, in situ artificial warming experiments and natural gradient research to evaluate direct effects (temperature increment on litter decomposition rates) and indirect effects (temperature increment on litter quality, soil organisms and vegetation) of global warming on litter decomposition in terrestrial ecosystems. Each method of study indicated that temperature elevation can often increase litter decomposition rates when litter moisture is maintained. Experimental warming studies implied that litter decomposition rates vary among species, methods and geographical sites. Global warming is likely to alter litter quality and decomposability, but these changes will not influence short-term litter decomposition rates. Interspecific differences in litter quality and decomposability are dramatically stronger than warming-induced differences. Thus, warm-ing-induced changes in species composition and community structure may have stronger impacts on lit-ter decomposition processes in terrestrial ecosystems. Effects of warming-induced changes in soil or-ganisms on litter decomposition are highly uncertain.
    REVIEW OF PROGRESS OF STUDIES ON SALT-TOLERANCE MECHANISMS OF ANNUAL HALOPHYTES
    ZHANG Ke, TIAN Chang-Yan, LI Chun-Jian
    Chin J Plan Ecolo. 2009, 33 (6):  1220-1231.  doi:10.3773/j.issn.1005-264x.2009.06.023
    Abstract ( 2003 )   PDF (456KB) ( 1949 )   Save
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    Halophytes, i.e., plants that can growth and reproduce in saline soil, have a series of evolutionary strategies to adapt to saline environments. Annual halophytes have been the main subject of salt-tolerance research, because their short life cycle facilitates culture and observation, enabling ease of experimentation, genetic transformation and plant regeneration. Bearing greater survival risk, annual halophytes have a set of mechanisms safer than those of perennial halophytes, including seed dormancy when subjected to high salt, fast germination after rehydration, polymorphism in morphology and germination, persistent seed bank and plastic resource allocation. After successful germination, the life stages of vegetation growth, development and reproduction can endure severe salinity stress; the so-called mechanism of salt tolerance is to mediate salt in vivo during plant life. According to differences among plant species, the mechanisms of salt tolerance can be divided into salt-dilution, salt-secretion and salt-exclusion. Based on analyzing domestic and foreign literature, we review and summarize the common types of annual halophytes and their salt-tolerant mechanisms, including seed characteristics, plant morphology and structure, biochemistry and ecological behaviors.

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