Research On Biological Characteristics, Salt-resistance, Flooding-resistance And Afforest Experiment Of Several Species Of Semi-mangroves

Semi-mangrove is one kind of amphibious woody plants growing in non-saline soil as well as growing in inter-tidal then be dominant species sometimes. Semi-mangrove has unique environment adaptability and important ecological functions, and most of them have special medcinal value and economic value. But as the reason of the constriction of gulf cities, the existing semi-mangrove is few and few, so conservation of them is increasing urgency. But domestic study of semi-mangrove is even not perfect, especially in reforestation operation. In this study, several common semi-mangroves incluing Thespesia populnea, Cerbera manghas, Heritiera littoralis, Pongamia pinnata have been studied. The biological characteristics of the above semi-mangroves have been mastered by observing the periodic biological phenomena and investgating the cold tolerance of the semi-mangroves in Qi'ao island; The salt tolerance and water resistant strength have been evaluated by simulation testing of the salt gradient of the seedlings and flooded in different depth in the greenhouse; The reforestation technology of semi-mangrove have been grasped by reforestation testing of Cerbera manghas in eight different sites. All of this study is based on the understanding of the biological characteristics and salt tolerance and water resistant strength of the semi-mangrove, in which site and species selecting of their reforestation were solved by combining part of the reforestation test, and theories and technology were offered for introduction, promotion, reforestation and scientific research work of semi-mangrove. The main results are as follow:1. The periodic biological phenomena of the four kinds of semi-mangroves:By the phenology observation of germination, leaf growth, bloom and fruiting of Thespesia populnea, Cerbera manghas, Heritiera littoralis, Pongamia pinnata from March 2007 to March 2008, the phenology law of them were preliminary mastered. The result showed that Thespesia populnea, Cerbera manghas, Heritiera littoralis were evergreen species, and Pongamia pinnata was deciduous species of which non-leaf stage was short that about from late of January to early of March. The flowering of Thespesia populnea was about from early of June to mid-August and fruit period was from mid-July to early of March of next year. The flowering of Cerbera manghas was from early of March to early of August and fruit period was from early of June to mid-November. Heritiera littoralis bloomed twice a year, the first was from early of March to late of May, the second was from early of July to late of August, and fruit period was from late of May to late November. The flowing of Pongamia pinnata was from early of March to early of June and fruit period was late of June to early of December.2. The cold resistance of the four kinds of semi-mangroves:Mastering the cold resistance of four kinds of semi-mangroves by inverstigating the freeze injury degree after the extreme low temperature winter-killing weather in 2008. It can provide theory basis for introduction, afforestation and promotion of the semi-mangrove in the future.3. The salinity test of the four kinds of semi-mangroves:Educing the range of salt tolerance of the four kinds of semi-mangroves by observation of growth, biomass, photosynthetic rate and physiological and biochemical indexes under different salt gradients, and combining with principal component analysis and fitness analysis. Thespesia populnea, Cerbera manghas and Pongamia pinnata could grow normally under the salinity which no more than 8 g.kg-1, while it was reverse under the salinity more than 11 g.kg-1. Heritiera littoralis could grow normally under the salinity which no more than 11 g.kg-1, while it was reverse under the salinity more than 14 g.kg-1. Salt tolerance of Heritiera littoralis was the strongest in the four kinds of semi-mangroves, which could tolerate the salinity about 11 g.kg-1.4. The flooding test of the four kinds of semi-mangroves:Educing the water resistant ability of the four kinds of semi-mangroves by observation of growth, biomass, photosynthetic rate and physiological and biochemical indexes under different water depth, and combining with principal component analysis and fitness analysis. It also can provide theory basis and technology support for introduction, afforestation and promotion of the semi-mangrove in the future. The seedling of Thespesia populnea, Cerbera manghas and Heritiera littoralis still growed normally under the water depth in 60d of stem, while reversed under the water depth to branch and all in the depth in 60d. The seedling of Pongamia pinnata was not adapted to growth under water depth to stem, to branch and all in the depth in 60d.5. The different sites reforestation test of Cerbera manghas:The survival rate of the eight different plot reforestations all were more than 80 percent. By regression analysis of the hight growth, the reforestation years and the physical and chemical properties of site soil of Cerbera manghas with multiple linear regression method, we can elicit the regression equation of its reforestation hight growth and reforestation years and the physical and chemical indexes of site soil (y1=1.3230x1+0.0090x2+ 0.6310x3-0.1480x4+3.1510x5+0.0001x6-6.7570x7+0.0004x8-4.3520) and the regression equation of its reforestation stem growth and reforestation years and the physical and chemical indexes of site soil(y2=3.9540x1+0.0090x2+1.9800x3-0.4340x4+9.5320x5+0.0001x6-20.0580x7+0.0030x8-15.6590). It offered theories for site select of Cerbera manghas and predicted growth condition of sea mango reforestation in different soil.