| Coastal shelter forest had played an important role in the coastal economic sustainabledevelopment, and it could improve the soil, reduce the wind speed and improve the regionecological environment. Study on the forest structure, soil improvement, resistance typhoonability of coastal shelter forest system at home and abroad had been done and greatachievements had been made. But now most of the coast shelter belt species was single,resistance insect ability and forest stability was poor, and few tree species could be used forafforestation. This paper studied the coast of shelter belt by the Yangtze river delta region ofShanghai and Nantong, separately from the coastal vegetation type distribution, reaction of treespecies under water and salt stress, comprehensive evaluation of experimental forest treespecies, soil fertility status under different types of shelter forest, in order to choose moreappropriate afforestation tree species and better configuration mode.. The results showed that:(1)The main kinds of vegetation communities on coast beaches in ShangHai area wereScirpus mariqueter, Spartina alterniflora Loisel., Phragmites australis, inside were Setairaviridis(L.)Beauv, Imperata cylindrica (Linn.) Beauv. And Solidago canadensis L.. Soil PHvalue and soil moisture content were the important soil factors which effected vegetationspecies diversity and plant distribution. Soil PH value had a significant negative correlationwith three communities diversity indexes, and the correlation coefficient was respectively-0.912,-0.933,-0.905; Soil moisture content had significant negative correlation with speciesrichness, and the correlation coefficient was-0.904.it also had a high negative correlation withthe other two diversity indexes, and the correlation coefficient was respectively-0.722,-0.865.With soil moisture descended and PH value reduced, the species diversity index of communitieson coast beach increased gradually.(2)Researches about various physiological indexes and the growth of four shelter foresttree species under water and salt stress showed that in the early stages, lower water and saltconcentration might stimulate the growth of root seedlings, but with the test time passed and thelevels of salt and water stress increased, it had a significant inhibitory effect on the stem, leaf,root growth and biomass accumulation of different species.(3)In the physiological indexes, plasma membrane permeability, chlorophyll, solubleprotein content,etc were relevant to trees water and salt resistant ability. But the change trendof each index had many different, which was effected by the concentration and time of stress.The reason might be the tree species had a certain physiological range of stress, and theresponse time of various tree species also had a big difference. So using a single physiologicalindex to analysis the trees resistance ability to water and salt stress was uncertain and difficult. (4)The principal component analysis about the four species resistance ability to salt andwater stress showed that: Sapium sebiferum>Taxodium mucronatum> Camptotheca acuminata> Koelreuteria paniculata, which was in agreement with observation results. By principalcomponent analysis, seedling height, ground diameter, biomass had a positive correlation withtwo factors, and the factor loadings were big; Plasma membrane permeability had a negativecorrelation with two factors; Factor1loading of free proline content was big, but factor2loading was very small; Other indexes association with two factors was different. In short, ifchoose physiological indexes to analysis trees water and salt resistance ability, it must choosesuitable for pressure and intimidation of stress, and should combine with various physiologicalindexes. In practical application, the choice can be directly observable form indicators such asseedling height, ground diameter, and biomass, morphological index, which were moreconvenient and reliable for operation.(5)AHP was used to construct the coastal shelter forest tree species selection evaluationindex system, totally covering19ranking points, including the major aspects such as the growthadaptability, ecological function, landscape effect and economic value. With the qualitative andquantitative method, test tree species were comprehensive evaluated. According to theevaluation results, Melia azedarach Linn., Firmiana simplex(L.)W.F.Wight, Koelreuteriapaniculata,etc were recommended as suitable planting species to muddy coastal shelter forest.(6)Soil nutrient indexes except catalase under six typical coast forest of shelter belt had asimilar distribution, and generally reduced with the increasing of soil depth and had asignificant difference, while they were higher than the beach. Soil bulk density and salt contentof Metasequoia glyptostroboides and Cunninghamialanceolata(Lamb.)Hook. were higher thanthe locust and Poplars, while the capillary porosity were lower than the latter. Soil nutrientcontent and enzyme activity of two mixed forest were better than pure forest.(7)The growth condition of the trees showed that: the trees in two mixed forest werebetter than trees in pure forest, the average tree height, diameter at breast height and crowndensity were significantly higher than the pure forest. The diameter to height ratio of locust andpoplars in mixed forests was respectively1:72.22,1:83.17, while in pure forests wasrespectively1:70.90,1:80.86; Cunninghamialanceolata(Lamb.)Hook. in mixed forest was1:89.97, while in pure forest was1:85.99. So trees in mixed forests the Taper was smaller,while fullness and stand Outturn Tables ratio were bigger than in pure forests.(8)The results of stepwise regression about soil fertility properties affecting speciesdiversity in herb layer showed that the main factor affecting species diversity was soil PH, andit had an obvious negative correlation. For species richness of herb layer,Simpson index andShannon index its explanation ability respectively achieved84.6%,56.1%and59.1%. Thenwas the soil total phosphorus. and it was positively related with herb layer species, itsexplanation ability for the three species diversity index respectively achieved11.3%,32.1%and31.9%. In addition, the soil moisture content, soil phosphorus content, effective soil bulk density, porosity and total nitrogen content had a certain effect on the herb layer of speciesdiversity.
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