| This study investigated the distribution of the invasive plant Spartina alterniflora along the Zhangjiang River in Fujian.Choosed the representational indigenous mangrove species Kandelia obovata,photosynthetic characteristics,chlorophyll content,osmotic potential,membrane permeability,free water and bound water content and other physiological characteristics of mature leaves of K.obovata and S. alterniflora were measured,and their adaptability to the intertidal habitats were analyzed.According to the distribution of plant community,this study set up four sample plots along the Zhangjiang River from the upstream to the downstream, growth characteristics of S.alterniflora in differeant growth phases were measured within one year,and the relationship between environmental factors and the growth of S.alterniflora were analyzed.At the same time,in the corresponding plots,we survey the number of K.obovata hypocotyl and the growth of K.obovata seedings through artificial implantation of K.obovata hypocotyl,the influence of the S.alterniflora community to the growth of K.obovata seedings were discuss.And the research results are as follows:1.S.alterniflora can grow and propagate along the river under different salinity gradients in Zhangjiang Estuary,compared to mangrove species,it has a wider ecological amplitude,as for the wider scope to adapt the salinity(2‰-30‰),and a different distributional state to different salinity.Show that S.alterniflora can adapt themselves to the different level of environment by phenotypic plasticity.2.In the same environmental conditions,the chlorophyll content and net photosynthetic rate in S.alterniflora are higher than K.obovata,and the difference is significant(p＜0.01);the transpiration rate and stomatal conductance of K.obovata leaf decline more quickly as the salinity decreasing,and lower than the S.alterniflora; S.alterniflora has lower osmotic potential and can accumulate a lot of material that can regulate the osmotic potential in the environment that has higher salt level.At the same time,its electrolyte extravasation rate is higer than those of K.obovata,and it can reduce the harm to the cytoplasm throgh its self-regulatory ability,so that which can adjust the extream environment.The water content between S.alterniflora and K. obovata are quite different(p＜0.01).The S.alterniflora has higer bond water content than that of K.obovata,which indicate that S.alterniflora has better ability of stranding the water.3.S.alterniflora proliferates by asexual reproduction.The seeding stage spreads rapidly.The appropriate salinity(about 15‰) stimulated the proliferation of the S. alterniflora while higer salinity(above 25‰) inhibited its proliferation.As the salinity increasing along the the river,the height,basal diameter and leaf area of the S. alterniflora are decreasing significantly.In the salintiy level of 25‰,the growth of the S.alterniflora start to be inhibited.Above-ground biomass of the individual decreased with the increase of the salinity.Howerer,the S.alterniflora has higher above-ground biomass per area which indicate that the 15‰salinity is the most appropriate salinity of the growth of the groups of the S.alterniflora.4.Hypocotyl of K.obovata can germinate within one month.Boitic and abiotic factors such as inter-tidal animal predation,tidal fluctuation,light and salinity could affect the fixation of the hypocotyl of the K.obovata.During the growth of the seedlings,light is an important factor.Being sheltered by the S.alterniflora,the seedlings of K.obovata grow slowly which has thinner stems and yellow leaves.Most of all,mature S.alterniflora plants were lodged in autumn,the seedlings of K. obovata were sheltered completely and died for starving of light.
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