Single Tree Characteristics Of Dominant Tree Species In Fuzhou Green Space And Their Response To Urban Lighting

Urban green space plays a vital role in improving the quality of urban ecological environment.The study of canopy structure,single wood characteristics,and relationships between urban lighting and dominant trees,which are the main component of urban green space,can provide a theoretical basis for designing tree planting models,quantifying collocation density and designing management.This type of research is of great significance for improving the urban environment and the effects of green space.In order to quantify the single tree characteristic of urban green space further,10 dominant trees in the urban green space were selected as research objects by plot investigation combined with some former studies.The tree height,diameter at breast height(DBH),and crown width of 10dominant tree species in Fuzhou were selected as the research indicators.The main research contents included:1)Characteristics of canopy structure of different dominant tree species;2)Dominant canopy width and growth space requirements of the dominant trees;3)Differences between dominant wood leaf characteristics and their influencing factors;and 4)Impact of urban lighting on urban street trees.The results indicated that:(1)There were linear relationships between the DBH and crown width,DBH and height of urban dominant tree species.The scale regression models of DBH and crown width of of Mangifera indica,Cinnamomum camphora,Ceiba speciosa,Bauhinia purpurea,Terminalia catappa,Dimocarpus longan,Ficus benjamina and Alstonia scholaris,had a large value of R2.And the correlation were also high.The correlation coefficients were all above 0.5 that there was a linear relationship between DBH and crown width with 95%probability.Except for Cinnamomum camphora,R2of the regression models of DBH and height of the other nine dominant trees were all less than 0.5.Cinnamomum camphoral,Ceiba speciosa,Dimocarpus longan,Terminalia catappaand Elaeocarpus decipienswere more than 95%likely to have a linear relationship between their DBH and height.(2)The requirement growth space of trees was pre-estimated by growth models that when DBH was 20 cm,the expectation value of requirement growth space of trees in Fuzhou urban space was 347.93 m3.Grow space increased with the increasing of tree crown when DBH were the same showing that their relationship was positive correlation while there was no significant relationship between them with the increasing of tree height.(3)The average values of Leaf length(LL),leaf width(LW),leaf area(LA),leaf thickness(VT),leaf thickness(LT)and chlorophyll contents(CHLC)of 10 tree species were 33.27 cm2,33.27 cm~2,4.30 cm,0.67 mm,11.35 cm,0.24 mm and 49.31 spad.The variation range of the leaf traits in similar habitats was large,and the variation coefficient was83.72%(LA)>56.68%(LW)>42.44%(VT)>37.40%(LL)>22.94%(LT)>18.74%(CHLC).The azimuth effect of leaf traits is obvious.Except for Elaeocarpus decipiensand Cinnamomum camphora,the leaf traits of different tree species were significantly different in different directions.There was a significant correlation between leaf traits that LL,LW and LA were extremely significantly positively correlated,VT and LT were extremely significantly negatively correlated,CHLC was extremely significantly positively correlated with LA,and extremely significantly negatively correlated with LT.The cluster analysis of leaf trait index showed that the 10 dominant trees could be divided into 3categories.(4)The light of street lamp affected the leaf area,leaf thickness and chlorophyll content of the trees differently.Also,different light intensities had different effects on the growth indexes of the same plant.And the same light intensity would affect different trees of a different degree,sometimes inhibiting the tree growth but sometimes promoted it.The results provided some theorical basis for further understanding the tree crown structure,the relationship between DBH and tree height and crown,and estimation of single urban tree growth space as well as some references for the choice,collocation,and management of dominant trees,and for the construction of city lighting facilities,all of which could make urban green space work better in the area of ecological effects and environment protections.