Study On Physiological And Ecological Effects Of Mangrove Plant Kandelia Obovata By Sonneratia Apetala

Mangrove is a woody plant grow in tropical and subtropical coastal intertidal area,it has great benefits for economic,society and ecological.In recent years,the exotic mangrove species Sonneratia apetala has became an important species for the mangrove wetlands restoration project in Chinese southeast coastal.Because it has strong adaptability,strong resistance and fast diffusion characteristics.However,there is a larger controversy in the academic community that whether the S.apetala is an invasion species.Because S.apetala is an alien species with introduction in China.It is pending further assessment that the alien species on safety for the native species.In order to assess that whether the S.apetala is an invasion species.In this paper,we set ‘the Spartina alterniflora prevention and ecological restoration demonstration bases in Dongshan Bay Wetland' as the sample plot.In the forest of the native mangrove species Kandelia obovata.We planted with different planting spacing of exotic species S.apetala.We had investigated and analysised the population characteristics of K.obovata,the physicochemical properties of C content,N content,P content,catalase enzyme(CAT)activity,superoxide dismutase enzyme(SOD)activity,peroxidase enzyme(POD)activity in K.obovata leaves,and the soil physical and chemical properties.The purpose was to provide a theoretical basis for the determination whether the alien species S.apetala is an invasion species.The results show as follows.1.The impact on the population characteristics of K.obovata.We had comprehensive comparated and analysised the data in 6 quarters,from April in2014 to July in 2015.S.apetala mixed planted with K.obovata,it did not lead to the surviving number of K.obovata appear significantly reduced.However,it significantly inhibited the tree height,basal diameter,leaf area,biomass and other indicators of K.obovata.With the S.apetala planting spacing decreasing,S.apetala did not lead to the surviving number of K.obovata appear significantly reduced.However,the inhibition level to tree height,basal diameter,leaf area,biomass,absolute growth rate(AGR),root to shoot ratio(R/S)of K.obovata were gradually significantly enhanced.The result instructed that,S.apetala had significant inhibitory effected on population characteristics of K.obovata.2.The impact on physiological and biochemical indexes of K.obovata leaves.After two years and three years later about S.apetala mixed planting with K.obovata,S.apetala made change the C,N,P content of K.obovata leaves.Specific performance as follow,S.apetala significantly suppressed the content of C,the content of N,the value of C:P and N:P and other stoichiometric indicators increasing on leaves of K.obovata leaves.It significantly promoted the content of P and the value of C:N and other indicators increasing on leaves of K.obovata.With the S.apetala planting spacing decreasing,it would be significantly enhanced the inhibition of the indicators increasing,such as content of C,content of N,value of C:P and N:P.At the same time enhanced the promoting of the indicators increasing,such as content of P and value of C: N.S.apetala mixed planting with K.obovata about two years and three years.S.apetala had changed the physiological of K.obovata leaves.S.apetala significantly inhibited the indicators increasing,such as content of chlorophyll a,value of chlorophyll a/b.But it promoted the increasing of the chlorophyll b contention.With the S.apetala planting spacing decreasing,S.apetala would be significantly enhanced the inhibition of the indicators increasing,such as content of chlorophyll a and value of chlorophyll a/b.at the same time it enhanced the promoting of the the chlorophyll b contention increasing.We finded that the effect of S.apetala on the CAT and POD enzyme activity on leaves of K.obovata were similar.They mixed planted about two years later,the effect began to appear significantly enhanced.With the S.apetala planting spacing decreasing,the increasing of the CAT and POD activity would be larger.However with the S.apetala planting spacing decreasing.There was a trend of K.obovata SOD activity is that it firstly significantly increased and then significantly diminished later.The result description that S.apetala mixed planting with K.obovata,it would have a significant impacted on physiological and biochemical indexes of K.obovata Leaves.3.The results of physical and chemical properties of the soil show that:(1)S.apetala had a certain extent to improve soil total carbon,total nitrogen,total phosphorus contention.And there were increasing with S.apetala planting spacing decreasing.(2)S.apetala could increase soil salinity and reduce p H value of the soil in some extent,but the phenomenon had little correlation with S.apetala planting spacing.(3)The vertical analysis showed that,S.apetala mixed planting with K.obovata.Firstly,it majorly increased the content of total carbon,total nitrogen,total phosphorus,salinity of 0-20 cm soil layer.Secondly,at the same time,it increased the reserves of total carbon and total phosphorus of 20-40 cm soil layer.Finally,it increased content of total carbon and total phosphorus of 40-60 cm soil layer,and at the same time,it improved the salinity and total nitrogen content of 20-40 cm soil layer.The soil p H value in mixed forest was bigger with the soil depth increasing,but the increasing trend were gradually declining.Above results show that,the population characteristics of K.obovata,the physiological andecological indicators on leaves of K.obovata and soil physical and chemical properties were impacted by the S.apetala in a certain way.What was more,some indicators were significant effected even extremely significant.We could Judged that there was a certain tendency to invade about the introduction of mangrove plants S.apetala.Therefore,we recommended that S.apetala introduction should be prudent.