Arbor Species And Their Environmental Services Of Urban Forest In Haikou

The objectives of the present research were to find out the arbor species components and their environmental services of Urban forest in Haikou. The findings indicated that:(1) The arbor species of Urban forest in Haikou had 229 species, 169 gengeras, 57 families. And among them, there were 110 common arbor species, 119 rare arbor species? 170 evergreen arbor species, 59 deciduous arbor species; 139 native arbor species, 90 exotic arbor species. These trees distributed in each green place situation, according to the type statistics, the unit affiliated green space accounts for 31.21%, the street green area accounts for 45.76%, the public green space accounts for 23.03%; according to the number statistics, the unit affiliated green space accounts for 55.46%, the street green area accounts for 18.78 %, the public green space accounts for 89.96 %.(2) The diversity of the urban street arbor species was low, in that Cocos nucifera Linn., Pterocarpus indicus, Ficusvirens Ait var sublanceolata, Ficus microcarpa L and Khaya senegalensis dominated 72.55% of all the arbor tree population.(3) Net photosynthetic rate and their diurnal variation of the tree species of Urban forest shown two kinds of growth tendency which followed the change of photosynthetically available radiation, one was a single peak curve, the other was a double peak curve.(4)The light use efficiency and the water use efficiency between the arbor species of Urban forest were difference. The arbor species with stronger light use efficiency were Lagerstroemia speciosa, Samalanga syzygium, Terminalia catappa and Pterocarpus indicus. The arbor species with stronger water use efficiency were Terminalia catappa,Syzygium cumini,Chorisia speciosa and Pterocarpus indicus.(5) The effect of carbon fixation,oxygen release,temperature reduction and humidification between the arbor species of Urban forest was difference, which was decided for the tree species 'photosynthetic and transpiration characteristics. In the test tree species, the arbor specie with stronger carbon fixation and oxygen release effect was Terminalia catappa, but Magnolia denudate was the worse. The arbor specie with stronger temperature reduction and humidification effect was Chorisia speciosa, but Pterocarpus indicus was the worse.(6) The gross quantity of carbon fixation,oxygen release,transpiration,heat energy absorption about the arbor species of Urban forest was considerable. In daytime, they can fixed CO₂ average for 7.28 g/m²/d, release O₂ average for 5.29 g/m²/d, release H₂O average for 1765.95 g/m²/d, absorb the city heat energy average for 4254721.35 J/m²/d.(7) Dust catching effect between the arbor species of Urban forest was difference extremely obvious. The mechanism to dust catching effect was complex, and its affecting factors were background environmental condition and tree species structure just likes leaf area and crown green capacity. Generally, dust catching effect to the arbor species with fluff,gland,extrude air cavity,coarse surface in the leaf blade was stronger than the others with smooth,non- wool surface. The arbor species with stronger dust catching effect were Hibiscus tiliaceus,Ficus hispida,Terminalia catappa and Chukrasia tabularis.(8 ) The traffic noise reduced to certain extent after passing through the green space and green belts. The street corner green space to reduce the noise effect was greater than the street green belts. In the street green belts, the best noise abatement effect was observed at the four green belts.In brief, this research quite systematically investigated the arbor species structure and their environmental services of Urban forest in Haikou, the findings might provide some scientificbases on matching the Urban forest in Haikou as more reasonable as necessary.