Evaluation On Substitute Species Of Artificial Coastal Windbreaks Based On Stress Wave Techniques In Hainan Island

The protective coastal forest system in Hainan Island has the function of preventing typhoon hazard and protecting the ecological security and economic security of Hainan.At present,the research on wind-resistance ability of Hainan protective coastal forest is rare.This project is mainly based on the method of investigation and experiment,first of all,to investigate the extent of the destruction of typhoon in protective coastal forest,to evaluate the ability of the protective coastal forest to resist typhoon.In many coastal areas of Hainan,stress wave technique was used to detect the stress wave of Casuarina species and some native tree species in protective coastal forest,to evaluat the relationship between each factor and stress wave about the wind-resistance of each tree species,provide technical support for protective coastal forest construction.It is helpful to enrich the species diversity of protective coastal forest,it can be used as a reference material for the selection of native tree species in Hainan.The main results were as following: Analysis of influence factors of stress wave propagation time It is found that there is no significant difference between the stress wave propagation time and the measured position in the four directions of the same tree,the same tree can be considered in all directions of wind-resistance.The higher the DBH,the shorter the time of stress wave propagation;there were significant differences in the diameter and stress wave propagation time of Casuarina equisetifolia.The Casuarina equisetifolia grow in different areas and the wind-resistance is different,there is no significant difference in stress wave propagation time.The wind-resistance of Casuarina equisetifolia in Changjiang is the strongest,but in Qionghai is the weakest.The wind-resistance ability of Casuarina equisetifolia at different ages was also different,the stress wave propagation time of middle age forest of Casuarina equisetifolia was significantly less than that of mature forest,but it's opposite in Sanya.Evaluation on wind resistance of main tree species and coastal native species on Stress Wave techniques in Hainan.The stress wave propagation time between the 7 species was also different,the stress wave propagation time of Casuarina equisetifolia is the shortest,the wind-resistance is the best,Acacia confuse and eucalyptus in the back.In artificial coastal forest,according to the elastic modulus,the wind resistance is from high to low: Casuarina equisetifolia?Eucalyptus? Acacia confuse?Cocosnucifera.In the coastal native tree species,according to the elastic modulus,the wind resistance is from high to low: Terminalia catappa? Cerbera manghas?Ficus hispida LinnL.The wind resistance of 7 species was evaluated by elastic modulus,from high to low:Cerbera manghas?Eucalyptus?Acacia confuse ?Terminalia catappa?Cocosnucifera?Casuarina equisetifolia L.? Ficus hispida Linn.So we can consider alternative screening species with Cerbera manghas and Ficus hispida Linn in the two coastal native tree species as the artificial coastal forest.Typhoon Rammasun impact on the protective coastal forest survey The Casuarina equisetifolia damage degree by wind lighter than the Acacia confuse after typhoon.Both Casuarina equisetifolia and Acacia confuse the damage is related to the distance from the coast,the closer distance from the coast,the higher the degree by the wind.The bigger the diameter susceptible to wind damage both in Casuarina equisetifolia and Acacia confuse,it may be affected by the age of the forest and the strength of the trunk.Planting density had no effect on wind-resistance,probably because the number of samples is not enough.Casuarina equisetifolia mature forest by wind damage rate as high as 82.61%,much higher than middle-aged and young forest,because the investigation of the protective coastal forest planting ages ago,growth status decreased and serious diseases and insect pests,performance the wind-resistance.In conclusion,the evaluation of wind resistance of trees needs to consider many factors,such as mechanical properties,growth state,age,environment and so on.The results of this study can provide a theoretical reference for the selection of new species of protective coastal forest regeneration,but the scope of the investigation is not broad enough and analysis is not deep enough,it is necessary to make a further study on the evaluation of the wind-resistance in Hainan Island.