Research On The Effects Of Growth And Physiological Characteristics Of The 4 Common Species Of Trees In Shanghai Under Seawater Stress

Shanghai is China's economic center, and international metropolis, which has a very high social economic status. Shanghai is in the east of China, Vulnerable to the typhoon. Because of the typhoon, there is very big loss in Shanghai for years. Building coastal shelter forest system is the most effective measure to prevent the typhoon from influencing the city. One of the weaknesses of the coastal shelter forest system in Shanghai is that there are not enough tree species. This trial has selected 4 kinds of common greening tree species in Shanghai, whch are Taxodium distichum, Sapium sebiferum (L.) Roxb, Koelreuteria paniculata, and Camptotheca acuminate In need of the construction coastal protection forest for muddy coast, the author had carried out the analyses on the seawater stress. Test set four processing level:Soil moisture for 75% of the field capacity, which was also called normal maintenance management for comparison (ck); The water below the soil surface 10cm, which was simulated high ground water level (t1); Complete saturated soil moisture was used for simulation natural state the stain hazards (t2); Soil moisture super saturation which the water above soil surface 2 cm or so,, was used for the simulation of water logging (t3).The results are as follows:(1) Both the roots'impact of Koelreuteria paniculata and Camptotheca acuminate was bigger than Taxodium distichum and Sapium sebiferum (L.) Roxb in the waters of the stress environment.The sensitive degree of Koelreuteria paniculata and Camptotheca acuminate were higher for the root surface area, length, volume, average diameter, which were all appeared rising at the beginning, dropping in middle. Both Taxodium distichu and Sapium sebiferum (L.) Roxb)'s root to environmental performance were not so obviously.(2)Between the different species of various physiological indexes had a significantly different tree species for seawater stress have obvious difference reaction. In addition, there were some differences on the different treatments on the chlorophyll content, relative conductivity and MDA content, diameter. However, there was no significant difference with test time for each index.(3)Plant growth index such as tree height, ground diameter, and biomass, was affected obviously under salt and water stress. Therefore, seedling height, ground diameter, and biomass, can be used to evaluate the ability of the tree species'stress resistance.(4)According to the principal component analysis results, the strongest resistance to the water stress was Sapium sebiferum (L.) Roxb, secondly was Taxodium distichum, the worst was Camptotheca acuminata and Koelreuteria paniculata.