Anti-typhoon Shelter Forest And The Protection Effects In Urban Area Of Sanya

Sanya is a tropical coastal tourism city, which located in South Hainan, China. Itstransportation, economy, society and life were frequently impacted by typhoon. Coastalanti-typhoon shelter forest can reduce wind speed and the losses caused by typhoon. It also canpurify the air and make the city beautiful. However, anti-typhoon shelter forest is scant and it isonly a small part of total green areas in Sanya. Few researchers have studied the anti-typhoonshelter forests in Sanya, especially on how to choose anti-typhoon tree species. To built abeautiful landscape and to improve biodiversity and ecological function of urban forestecosystem in Sanya, we select several tree species to observe their responses to typhoon.GIS techonology was used to investigate the green area status and green plant resources inSanya urban areas.Anti-typhoon shelter forests were built to to observe the the growthcharacteristics of the main tree species impacted by typhoon.(1) By analyzing the satellite image data in2010from Sanya, the number of green areamosaics is6764and the total green area is about3964.49hm2. There are five categories ofgreen areas, including park, nursery green area, green buffer area, supplemental green area andother green area. The area of supplemental green area is the largest, about2953.91hm2and upto74.50%of all green areas in Sanya. The area of green buffer is the smallest, about77.13hm2and up to1.95%of all green areas in Sanya. The areas of public park, nursery green area andother green area is297.46hm2(7.50%),303.15hm2(7.65%) and332.84hm2(8.40%) of allgreen area in Sanya, respectively.(2)184species were planted in Sanya urban areas. Areca triandra, Roystonea regia,Chrysalidocarpus lutescens, Caryota ochlandra, Cocos nucifera, Delonix regia, Bougainvilleaglabra, Ficus altissima, Ficus microcarpa var. pusillifolia, Pterocarpus indicus, Tamarindusindica, Plumeria rubra, Casuarina equisetifolia and Araucaria cunninghamii were frequentlyplanted. The public park and supplemental green area have the most abundant species, while the green buffer area has fewer number of species. The vertical community structure in greenarea are mainly single layer or double layers. The horizontal community structure is mainlymosaic distribution.(3) Seventeen tropical tree species were planted in the anti-typhoon shelet forests and theirgrowth conditions were observed for three years, to learn their early growth properties. ResultsshowedathatanineaspeciesaincludingaKigeliaaafricana,aKhayaasenegalensis,aAclenantherapaeonina,aErythrophloeumafordii,aTabebulaarosea,aGrevilleaarobusta,aPterocarpusaindicus,Terminalia mantaly and Bischoffia polycarpa grew faster and could be used as upper-layertrees or pioneer species in the anti-typhoon shelter forests. Nine species including Khayasenegalensis,aTabebulaarosea,aElaeocarpusahainanensis,aPterocarpusaindicus,aMadhucalongifolia,aDracontomelon duperreanum,aTerminalia mantaly,aSamanea saman and Bischoffiapolycarpa could defend the strong typhoon and be used as ormental trees, which have beautifultree shapes, flowers and fruits. These trees can be used to build the anti-typhoon shelter forestsin Sanya urban area by tree species layout.(4) The wind defence performance was also measued in the anti-typhoon shelter forest.Results showed that wind speed reduced significantly after typhoon pass through theanti-typhoon forest belt. After that,wind speed increased in the open area but it is still smallerthan the wind speed before passing through the forest belts. The older the forest belt built, thestronger the wind defence performance is. Therefore, in order to increase the complexity anddiversity of the anti-typhoon shelter forests, these wind defence tree species could be used asmain tree species in the anti-typhoon shelter forest and planted with native species together.It isan effective method to increase the wind defence ability and enlarge the green areas together inSanya.