2014 Vol. 31, No. 5
To reveal structural characteristics, a study on spatial continuity for DBH of dominant plant populations in an evergreen broadleaved forest was conducted. A typical plot, 100 m×100 m, in National Nature Reserve of Mount Tianmu, Zhejiang was surveyed for tree diameter at breast height (DBH) above 5 cm with Total Station (Leica TCR702Xrange) that is used to measure tree coordinates. Also, dominant plant populations were first determined using the Dominance Index and then completed using a spatial statistical analysis with GS+ software. Results showed that DBH of the dominant plant populations of evergreen broadleaved trees in the reserve had a spatial dependence of 0.7 and a range of spatial continuity of 5.7 m.Thus, the structural complexity for this evergreen broadleaved forest showed a high spatial dependence and a small range of spatial continuity.
Spatial position is close to the function of forest, in order to get the rule of spatial distribution and make forest management activities, fifteen mixed conifer-broadleaf forest plots with 30 m×30 m surveyed at Mount Tianmu, Zhejiang. Electronic Total Station was used to measure the plots border and the accurate location of trees which DBH was above 5 cm, at the same time, species identifing, listing, and every tree detection were prepared. Three parameters-mingling index, neighborhood comparison, and uniform angle index-were used to describe spatial structure. Results showed that the mingling index was between 0.700 and 0.900 with a 0.712 average. For stand spacing distribution patterns, the zero and weak mixtures of tree species had the lowest proportion, the strong and extremely strong mixtures of many different tree species had the largest proportion. The average neighborhood comparison was 0.477 with relatively less heterogeneity within the spatial structure units and most of the individual differences at a medium level. Approximately half of the trees within the forest stand belonged to dominant tree species with overall dominance having the potential to increase. Tree species size varied. The growing space of Pinus massoniana was less than other species; no obvious differences in growing space were found for Cunninghamia lanceolata, Liquidambar formosana, and Quercus glandulifera var. brevipetiolata, but other species occupied a dominant position. These mixed coniferous-broadleaved forests were relatively stable with an average uniform angle index of 0.533 most of which was close to 0.500. No obvious uniform or uneven forest structure was noted with overall cluster distribution. Future succession of the forest stand was predicted to have a random distribution. In summary, the mixed coniferous-broadleaved forest at Tianmu Mountain had diverse species with a suitable, relatively stable forest structure.
To explain the relevance of stand density and understory vegetation diversity in cold, temperate coniferous forests, the Picea (spruce) forests in the Pangquangou Nature Reserve of Guandi Mountain, Shanxi Province were selected as a representative study. In the experiment, twenty seven sample plots were set in stands with nine stand densities (475, 500, 525, 675, 700, 800, 900, 925 and 1 000 trees·hm-2) and three replicates. The sample plot area is 400 m2 (20 m×20 m). Species composition of understory herbaceous plants was determined in all replicates and the relevance between stand density and diversity index was analyzed using Simpson, Shannon-Wiener Diversity, Pielou Evenness Indexes and Richness. Results showed (1) 37 species of herbs belonging to 35 genera in 18 families.(2) The diversity indexes of herbaceous plants decreased with an increase in stand density:with a stand density of 475 trees·hm-2 the Simpson Index was 0.82, the Shannon-Wiener Index was 1.97, and the Pielou Index was 0.71; whereas, at 1 000 trees·hm-2 the Simpson Index was 0.54, the Shannon-Wiener Index was 1.18, and the Pielou Index was 0.39.(3) With different stand densities, the Richness of herbaceous plants ranged from 14 to 23. Thus, in cold, temperate coniferous forests with Picea as the main species, the diversity index of understory herbs decreased with a stand density increase.
Infiltration in forest which is not well understand till now may be quite different from that on the bare land. In order to study water conservation mechanisms and soil water infiltration law for a forest, an ECH2O soil moisture content detection system was used to measure the volumetric soil water content (VSWC) at six soil depths:5, 15, 30, 40, 60, and 100 cm, for a Quercus acutissima forest in the suburbs of Nanjing, China. VSWC with light, moderate, and heavy rainfall conditions was analyzed along with the VSWC curves of different soil depths. Also, the response of the VSWC increasing rate and its peak value as well as the peak value time to rainfall were analyzed. The response curve of lateral flow to precipitation intensity at each soil depth level between 0-100 cm was studied and the affect for the law of lateral flow on variation of VSWC at each soil depth was determined. Results showed that the VSWC at 5 cm and 15 cm levels changed synchronously with rainfall, at rainfall of 6.8 mm, 11.8 mm, 36.8 mm whose variation of VSWC are 1.48% and 2.10%, 5.21% and 5.72%, 7.55% and 7.85% respectively. And as the soil level deepened, the changing synchronicity between the VSWC and rainfall declined gradually because peak VSWC was 1-2 h lateral at middle rainfall to storm while showing no change at small rainfall. At a rainfall intensity of 0-4.0 mm·hm-1 the varying amplitude for VSWC increased from the surface to 30 cm soil depth, with the variation of VSWC at 5 cm, 10 cm, 30 cm soil depth being 1.48%, 2.10%, 2.90% respectively; at 12.0-30.0 mm·hm-1 varying amplitude for VSWC decreased from the surface to 60 cm soil depth, whose variation of VSWC are 8.01%, 7.85%, 6.39%, 5.96%, 2.63% respectively, but greatly increased at 100 cm soil depth, that is 8.97%. For selected 3 precipitation events of 6.8 mm, 16.2 mm, 36.0 mm, from 2011 to 2012, when rainfall intensity was less than 60 mm·hm-1, the precipitation needed to increase soil water content during precipitation was much higher than actual rainfall without any happening of surface runoff, of which the biggest lateral water flow was 2.1 mm·hm-1, 2.4 mm·hm-1 and 28.7 mm·hm-1 respectively. Thus, a phenomena of non-saturated water infiltration in forest soil occurred.
To explain the water utilization mechanism of a Cyclobalanopsis glaucoides virgin forest on the Central Yunnan Karst Plateau in southwest China, and its adaptive strategies in an arid karst habitat, a stable isotope technique was featured to determine soil-water levels utilized by plants. Several dominant plant species (C. glaucoides, Olea yuennanensis, and Pistacia weinmannifolia) were selected and tested with oxygen isotopes of water on stems and soils from the virgin forest. Using IsoSource model calculations the contribution of different water samples was determined. Results revealed that water utilization positions and proportions for C. glaucoides in the primeval forest and its accompanying trees varied in time and space, and were competitors for water. During dry seasons, C. glaucoides, mature O. yuennanensis, and young P. weinmannifolia used soil water from depths of 55-115 cm with more groundwater used for mature C. glaucoides and mature P. weinmannifolia. In rainy seasons, because of the precipitation, 100% of the mature C. glaucoides, 33.3% of the O. yuennanensis, 66.0% of the P. weinmannifolia, and 37.4% of the young P. weinmannifolia used the 20-55 cm soil-water level.
Fertilization is an important intensive operation for improving economic benefits of a Phyllostachys edulis stand. To determine the amount of N fertilizer needed from practical and theoretical aspects, the effects of N fertilization (at 100, 250, and 400 kg·hm-2) on the production of winter shoots, spring shoots, bamboo stems, and diameter at breast height (DBH) of a Ph. edulis stand from 2006-2011 were measured using complete randomized design (CRD). The Ph. edulis stand without addition of N fertilizer was the control. Each treatment and the control had 3 replicates, and Duncan test was used to analyze the difference. The photosynthetic pigment content and photosynthesis of bamboo leaves were also calculated. Results showed that 250 kg·hm-2 N fertilization significantly increased (P < 0.01) new bamboo production of winter shoots, 6.8 fold; spring shoots, 2.0 fold; bamboo stems, 1.1 fold; and DBH 33.3%. However, no significant differences were found for the 100 and 400 kg·hm-2 treatments. After fertilization, the photosynthetic pigment content, light saturation point, and net photosynthetic rate increased; whereas, the light compensation point and intercellular CO2 concentrations (Ci) decreased, indicating that N fertilization raised photosynthetic ability. Among the three fertilization level, 250 kg·hm-2 had the best effect on promoting Ph. edulis photosynthesis. Therefore, 250 kg·hm-2 was the best fertilization rate for Ph. edulis stands.
To provide a theoretical basis with Eucommia ulmoides for ecological adaptability and on breeding of new varieties, leaves of two ornamental E. ulmoides clone seedlings ('Hongye' and 'Xiaoye') were selected and compared. For each clone, three leaves (i.e. three replicates) were selected and measured alternatively. Light response curves for both clones were measured using a Li-6400 and a rapid light curve found with a PAM2500. Light response curves under different temperatures for 'Hongye' were measured too. Photosynthetic parameters were computed by rectangular hyperbola model. Equations of linear regression between photosynthetic parameters and the temperatures were fitted. Results for 'Hongye' leaves (in μmol·m-2·s-1) showed a light compensation point of 23.96, a light saturation point of 495.94, a maximum net photosynthetic rate of 16.907, and a respiration rate of 1.666; the initial slope was 0.078.'Xiaoye'leaves(in μmol·m-2·s-1) revealed a light compensation point of 26.487, a light saturation point of 521.920, a maximum net photosynthetic rate of 18.502, and a respiration rate of 1.674; the initial slope was 0.070. There were significant regression relationship between temperatures and photosynthetic parameters of 'Hongye'(R2=0.479-0.959). These results suggest that that E. ulmoides is a strong heliphilous species and temperature has significant effects on E. ulmoides photosynthetic parameters.
To understand the chemical relationships of Prunus cerasifera with others turfgrass plants, the allelopathic effects of an aqueous extract from different organs and rhizosphere soil of P. cerasifera on seed germination and seedling growth of four turfgrass plants:Trifolium repens, Medicago sativa, Agrostis tenuis, and Lolium perenne, were studied. Seed germination was tested indoors using a biological monitoring method, and seedling growth was tested in a pot experiment. Results indicated that the root, stem, and leaf aqueous extracts of P. cerasifera at 0.05 g·mL-1 concentration significantly inhibited (P < 0.01) seed germination of T. repens with leaf> root> stem. Leaf litter and rhizosphere soil extracts of P. cerasifera also had a strong inhibition on seed germination of T. Repens. Leaf extracts inhibited seed germination of T. repens and M. Sativa with A. tenuis and L. perenne being promoted at lower concentration and being inhibited at higher concentration. For seedling growth, leaf extracts promoted T. repens and M. sativa, and inhibited A. tenuis and L. perenne. Overall the allelopathic sensitivity was in the order of A. tenuis> L. perenne> T. repens> M. sativa. Additionally, the overall allelopathic sensitivity of M. sativa was positive, but the others were negative. These results provide a basis for allelopathic application of P. cerasifera.
Ethylene responsive factors (ERFs), one kind of APETALA2(AP2)/ERF transcriptional factor that responds to environmental stimuli, especially to pathogen attacks, play an important role in plant-pathogen interactions. Recently, we noticed that one ERF-18 gene involved in the pathogenesis processes of the poplar stem canker disease of some poplar hybrid clones. However, the expression patterns of this gene response to other environmental stimuli are unclear. In this study, the phylogenesis, structure, and expression patterns of one Populus deltoides ERF gene (PdERF-18) were reported. Treatments including salicylic acid and jasmonic acid (JA) induction, Botryosphaeria dothidea and Agrobacterium tumefaciens (Rhizobium radiobacter) inoculation, mechanical stress, high temperature, salt stress, and dehydration stress were tested with real-time reverse transcription polymerase chain reaction (RT-qPCR). Results revealed a PdERF-18 coding for a B-6 member in the ERF family B. The 14th alanine and 19th aspartate residues in the AP2/ERF domain, typically characteristic of plant ERFs, were altered with an aspartate site substituted by a glutamate (an amino acid residue with stronger electronegativity than aspartate) in the coding product for the PdERF-18 gene implying that PdERF-18 might have some additional functions besides its resistance to a pathogen. RT-qPCR data of the diverse stresses revealed up-regulated expressed patterns in P. deltoides. Also, similar expression pattern responses for both B. dothidea and JA as well as responses to A. tumefaciens and salicylic acid were found. Thus, it was inferred that the JA/ethylene (ET) transduction pathway regulated gene expression in poplar canker pathogen attacks, but the SA pathway was involved in the responsiveness to poplar crown gall disease; therefore, it was deduced that PdERF-18 was a multi-functional transcriptional factor involved in many biotic and abiotic stresses.
To explore the relationship between leaf and seed nutrients of Torreya grandis ‘Merrillii', eight mineral elements (N, P, K, Ca, Mn, Cu, Mg, and Zn) were quantified. Then, analysis of their dynamic changes during fast growth and seed filling was conducted using a correlation analysis. Results at the early stage when seeds enlarged showed 1) decreases in the leaves for N (26.5%), P (23.1%), and K (36.2%); decreases in the seeds for N (15.4%) and P (8.3%); and an increase in the seeds for K. 2) In leaves, Ca, Mn, and Cu increased, but Mg decreased; whereas in the seeds at first they decreased but later increased. 3) In fruits, Ca, Zn, and Mn were significantly and positively correlated (r=0.906, 0.924, 0.924, P < 0.05) to P in leaves; whereas, P in seeds was significantly and negatively correlated (r=-0.960, P < 0.01) to Ca in leaves. Therefore, to have a positive impact on yield and quality of T. grandis ‘Merrillii', before the fast growth of seeds, more N, P, and Ca fertilizer should be applied; in mid-July, K fertilizer should be added; post-harvest, Mg fertilizer should be applied; and a combined application of microelements and P fertilizer should be added during seed development.
To explore the effect and the degradation pathway of each acid catalyst degradation of microcrystalline cellulose. Microcrystalline cellulose (MCC) was utilized as the raw material with a hydrothermal synthesis reaction being used for degradation. The MCC degradation products were treated with sulfuric acid, sodium periodate, and phosphotungstic acid and then analyzed by gas chromatography-mass spectrometry (GC-MS) for structure and mechanisms of the degradation products. Results showed that when different acids acted on microcrystalline cellulose, they gained organic acids, ketones, aldehydes, alcohols, or esters. However, different acids received specific degradation products with varying structure and content. Analyzing the reaction mechanism showed that degradation mechanisms differed.
To produce wood based particleboard panels with favorable fire retardant properties, the influence of three different fire retardant agents and resins (phenol formaldehyde (PF); 4, 4-diphenyl-methane diisocyanate (MDI); and urea formaldehyde (UF) on the physical, mechanical, and flammability properties of particleboard panels was studied. Results showed that after fire retardants were added to the particleboard panels, most of the mechanical and physical properties of the panels decreased, but the modulus of elasticity (MOE) of the panels with MDI significantly improved (P=0.002). The PF resin reduced smoke density, but did not improve the flame-retardant property; whereas, the MDI resin increased the flame-retardant property, but also increased smoke density. For panels with flame-retardant agents, smoke density and OI of panels with UF were 77.86%-103.64% but without flame-retardant agents were 124.68%-153.21%. For panels with flame-retardant agents, smoke density and OI of panels with PF resin were 27.80%-87.53%, but without flame-retardant agents were 123.95%-142.60%. The smoke density and OI of panels with MDI and flame-retardant agents were 108.75%-203.04%, but without flame-retardant agents were 137.50%-163.24%. Since a favorable combination of reduced smoke density and improved flame-retardant properties was not obtained more research should be conducted in this area.
Eucalyptus pellita wood was radiation heated under different temperatures in vacuum condition. Effect of different temperatures and testing positions, contains different wood board depths, lengths, and widths, to heat absorption per unit mass (Qm) and average temperature increasing rate (VTmean) were studied. Influence degree to Qm and VTmean of the parameters were judged by analysis of covariance, and the degree of influence were weighed by LSD multiple comparisons. The results showed that:main factors which effecting VTmean and Qm during vacuum heat treatment were heat treatment temperature and testing board thickness, influence of distance from test point to board top and side was quite limited; VTmean and Qm went up as heat treatment temperature increasing and thickness enhancing, effect of depth increased significantly different at 0.05 levels when the depth difference reached up to 20 mm. The phenomenon of uneven heat transfer should to be taken into account when the thickness of the treating board was more than 40 mm.
To analyze the relationship between anti-typhoon performance and wood properties, eight wood property factors (oven-dried density, fiber width, fiber length, ratio of fiber length to width, modulus of elasticity, shearing strength, modulus of rupture, and impact toughness) of six tree species (Calophyllum inophyllum, Casuarina equisetifolia, Melia azedarach, Acacia mangium, Eucalyptus grandis×Eucalyptus urophylla, and Acacia crassicarpa)and their anti-typhoon performance were tested. A correlation analysis between anti-typhoon performance and wood properties was conducted. Also, a regression analysis was conducted to determine forecasting and evaluating values for wind-resistance performance. Results for the six tree species showed that each wood property factor presenting a significant difference (P < 0.01) from another. Typhoon-resistance of the trees was in the order:Calophyllum inophyllum> Casuarina equisetifolia> M. azedarach> A. mangium> Eu. grandis×Eu. urophylla> A. crassicarpa. The direct linear correlation between anti-typhoon performance (total wind damage) and fiber width (r=0.958 0, P < 0.05), and that between total wind damage and ratio of fiber length to width (r=-0.868 0, P < 0.05) were found. Regression analysis showed that fiber width (r2=0.917 8, P=0.002 6) and modulus of elasticity (r2=0.972 5, P=0.009 2) got into the regression equation and had the greatest impact on total wind damage. The fiber width (r2=0.890 5, P=0.004 7) got into the regression equation and had the greatest impact on wind-resistance value. Also, ratio of fiber length to width (r2=0.825 9, P=0.012 1), shearing strength (r2=0.974 0, P=0.176 9), and modulus of elasticity (r2=0.919 5, P=0.158 6) got into the regression equation and had the greatest impact on 1st level damage (broken trunk and trunk lodging); whereas, fiber width (r2=0.818 8, P=0.106 4) and impact toughness(r2=0.882 4, P=0.055 6) got into the regression equation and had greatest impact on 2nd level damage (trunk heavily skewed). The forecasting value fitted well with the actual value. Thus, the regression equation could be used for forecasting and evaluating wind-resistance performance of other tree species.
To find the optimize scheme of bamboo piece quality for specific product, making 32 mm bamboo curtain plywood by using different quality of bamboo pieces. Comparisons and analyses of their longitudinal modulus of rupture (MOR) and modulus of elasticity (MOE) were conducted. Results for the range of comparisons showed:1) A smaller thickness error and higher surface quality of bamboo pieces significantly increased the strength of bamboo curtain plywood; 2) The smaller the thickness error, defect, and degree of irregular bending, and the better the surface quality; the higher the numerical value of the longitudinal MOR and MOE; 3) With thickness error < 0.2 mm, longitudinal MOR and MOE were greatest:MOR=124.5 MPa and MOE=7 468.3 MPa. It means that high-precision bamboo split machine is necessary to make high quality of bamboo pieces in order to improve the performance of the bamboo curtain plywood.
The ancient native and evergreen landscaping tree, Cinnamomum camphora is found seriously damaged by a newly occurred boring weevil pest in gardens of Shanghai. The pest, which identified to be Pagiophloeus tsushimanus Morimoto, 1982, belongs to the tribe Hylobiini in the subfamily Molytinae of Curculionidae. It is a new record to China and currently discovered in Shanghai and Fujian. The species is characterized by its four rough granules on elytra, with two on intervals Ⅲ and the other two on intervals Ⅴ. Difference between male and female could be found on the ventrites Ⅰ-Ⅱ, which are convex in female and concave in male. The study provided the damage, diagnosis, habitus photos, and detailed terminalia illustrations of the pest.
Reticulitermes chinensis is a major pest to damage old standing trees. Mirex bait is the main chemical to control R. chinensis over the last several decades. However, mirex has been banned because of its negative effects on the environment. In order to find suitable bait to control R. chinensis, the control effects of 5.0 g·kg-1 hexaflumuron bait, 1.0 g·kg-1 chlorfluazuron bait, 1.0 g·kg-1 triflumuron bait, and 0.8 g·kg-1 sulfluramid bait against the R. chinensis colonies have been studied in the suburban woodlands Nanjing City of Jiangsu Province and Hefei City of Anhui Province. Results indicated that the foraging distance of R. chinensis was between 0.15-2.10 m far from their nest in woodland. The number of R. chinensis in a colony was between 17 422-15 8731. The 5.0 g·kg-1 hexaflumuron bait, 1.0 g·kg-1 chlorfluazuron bait and 1.0 g·kg-1 triflumuron bait could completely eliminate the colony of R. chinensis. The average weight of bait to eliminate a colony was 93.6 g for 5.0 g·kg-1 hexaflumuron bait, 107.9 g for 1.0 g·kg-1 chlorfluazuron bait and 82.5 g for 1.0 g·kg-1 triflumuron bait. The time to eliminate an entire colony was 152-305 d for 5.0 g·kg-1 hexaflumuron bait, 152-365 d for 1.0 g·kg-1 chlorfluazuron bait and 244-305 d for 1.0 g·kg-1 triflumuron bait. The 0.8 g·kg-1 sulfluramid bait could eliminate only parts of R. chinensis colonies, and would be banned in the coming years.
This paper used Costanza and Chee's value substitution method to calculate the value of Catharsius molossus' ecosystem services including dung decomposition, pasture pollution treatment and nitrogen cycle in Henan Province. The economic value of the three services added up to 5.1 billion RMB which indicated that the insects provided substantial value of ecological services. The proposed method to calculate the value of insects' ecosystem services would promote the research on the valuation of insects' services. The paper also discussed the tradeoff between ecosystem services and decision-making of government.
The purpose of this study was to evaluate the health of ancient Platycladus orientalis trees with nondestructive methods and to establish and adjust in a timely manner the relative protection and rejuvenation measures. Based on an open space survey and opinions of experts, health of the 19 ancient P. orientalis trees in the mausoleum of the Yellow Emperor was assessed. Thirteen evaluation indicators in terms of trunk, crown, and root, including stem gradient, bark integrity, trunk injury, and trunk pest were chosen using the Delphi-analytic hierarchy process (AHP) to determine relative indicator weights. Finally, a model for assessing ancient P. orientalis health was established and its health was divided into 4 grades. Results indicated 2 trees being healthy, 9 trees being sub-healthy, and 8 trees being unhealthy. The final scores symbolizing the health of the ancient trees were matched to the results of the open space survey with the main influences on tree health determined as dieback, pests and diseases, trunk injury, poor soil conditions, and interference, which can help to make the protection plan.
The success of the cause of global carbon emission reductions depends largely on China's reduction effects. As an important subject of China's carbon emissions, the enterprises' emission reductions are the fundamental guarantee of the realization of reduction target. According with the current situation of China, voluntary emission reduction should be the ideal transition mode for enterprises to adopt, and voluntary agreement has been proved to be an effective mechanism to reduce emissions. This paper studies the enterprises' emission reduction choices based on voluntary agreement with the evolutionary game theory method, and then gets the results that increasing government supports, reducing the enterprises' reduction costs, enhancing the publicity and other aspects can improve enterprises' vested interests, and as a result enterprises are more inclined to choose voluntary agreement mode. Finally this paper raises some countermeasures:(1)further increasing government funds and policy incentives to promote enterprises' voluntary reduction; (2)building a variety of reduction ways to lower enterprises' abatement costs effectively; (3) paying more attention to publicity of low-carbon idea to raise social identity of the low-carbon enterprises.
During cold winters, application of methane gas production has had problems, such as a low use-rate, a short use-time, and poor comprehensive benefits. To introduce the specific and assessed economic, ecological, and social benefits of biogas projects, solar energy was used for heating to solve the cold winter biogas production problems at the Zhuji City Silverlit Ecological Farms Biogas Project. Results from the project showed a maximum pool temperature for the anaerobic fermentation tank of 22.8℃, a minimum temperature of 12.7℃, a gas production rate that remained 75 m3·d-1 or more, and an annual income of 230 000 Yuan. Thus, it would be worthwhile to large-scale application of a solar collector system.
Bombax malabaricum, a native species in the south and southwest of China, has drawn wide attention because of its high ornamental and medicinal values. From the perspectives of characteristics, forest plantation, and landscape application of Bombax malabaricum, the paper reviewed its distribution, morphology, seed propagation, clone, transplanting, growth characters, ornamental value and landscape application. The paper also proposed some suggestions for the further plantation cultivation, development and utilization of Bombax malabaricum resource, including germplasm resource collection, improved varieties breeding, afforestation technology, utilization of tourism and landscape resources.
Soil salinization, one of the severest environmental problems, results in accumulation of salt ions in cells that poisons plants. With NaCl stress, Na+ enters into the cell via non-selective cation channels leading to plasma membrane depolarization. This activates the outward K+ channel draining K+. In salt-tolerant plants, K+ efflux is inhibited, so cells maintain a higher K+/Na+ to reduce salt stress damage. In plasma membranes, H+-ATPase transports H+ out the cell, so that the H+ can form a proton inducing force to drive the Na+ efflux via an Na+/H+ antiporter. With salt stress, Ca2+ flows into the cell playing an important role in the regulation of Na+ and K+ flux. At the same time, Cl- outflow from the cell with salt stress may couple with Na+ efflux. To aid in helping the further study of ion flux, the flux of these ions and their regulation mechanism with salt stress are summarized in this paper.
Cycas debaoensis, an endemic species in China, is classified as a first grade national, key protected wild plant and was introduced to the Botanical Garden from Debao, Guangxi in 2002. This paper reports the ex situ conservation of C. debaoensis in Guilin. In the study area, leaf sprouting of mature plants happened from May to July, flowering occurred from May to June, and fruit maturity was from the middle 10 days to the last 10 days of November. Stem growth was slow with plant height averaging an increase of 1.90 cm a year, and ground-level diameter averaging an increased of 2.14 cm a year. Since C. debaoensis seed needed dormancy and could germinate after ripening, wet sand was the preferred storage method, having a seed germination rate of about 80%. Through several year's observation, C. debaoensis from calcareous soils in the southern subtropical zone could grow well, bloom, bear fruit, and have strong cold resistance in acidic soils. Ex situ conservation was successfully carried out in Guilin Botanical Garden.
To establish a tissue culture system for commercial propagation, buds induced by mature embryos were used as explants to study the effect of different hormone combinations on bud multiplication and root induction of Gigantochloa tekserah. Results showed that for bud multiplication, since the highest proliferation coefficient was 2.11 and cluster buds grew well, Murashige and Skoog's (MS) medium supplemented with 3 mg·L-1 6-benzylaminopurine (BA), 0.01 mg·L-1 thidiazuron (TDZ), and 0.3 mg·L-1 1-naphthylacetic acid (NAA) was the optimal medium. The best rooting medium was 1/2 MS supplemented with 3 mg·L-1 indole-3-butyric acid (IBA) because of the rooting rate was up to 70% with long, thick roots. After transferring to an equal ratio mixture of peat, vermiculite, and perlite, the survival rate of hardening plantlets was 100%.
Three naturalized plant species newly discovered in Ningbo City, Zhejiang Province were reported: Euphorbia prostrate(Euphorbiaceae), Senecio vulgaris(Compositae) and Erigeron strigosus(Compositae).