Characteristics And Effect Factors Of Leaf Area Index Of Main Tree Species In Urban Parks Of Fuzhou

The urban park green space is of great significance to improving the urban environment.The leaf area index(LAI)is one of the most basic and important ecological parameters of urban green space ecology,which is of great reference value to measure the ecological efficiency and greening effect of urban parks.In this study,we study LAI of 75 kinds of common shrubs and trees in Fuzhou urban parks by typical tree species survey methods in typical plots and using LAI-2200C canopy analyzer with the height,diameter at breast height,crown width,and LAI as index.The major context includes:1)The effects of tree species and vegetation characteristics on the LAI index of urban park green space.2)The influence of major environmental factors on LAI index of park vegetation.3)Monitoring the change of index of typical vegetation LAI in different seasons.The results show that:1)The LAI index of urban green space is closely related to tree species.Under the same ground conditions,,leaf area indexes of different tree of species are different.The average LAI of shrub vegetation(4.19)is higher than that of tree vegetation(3.06),and the average LAI of evergreen vegetation(3.82)is higher than that of deciduous vegetation(3.43).There is also a significant difference in the leaf area index of tree species in different urban parks.LAI of the same species is relatively consistent.The average leaf area index of local tree species(4.04)is also significantly higher than that of exotic species(3.31).There are also significant differences in leaf area index distribution among different tree species.LAI of shrub distribute between 1.81?7.90,while the one of tree distributes between 1.06?6.85.Shrub vegetation distributed more widely than tree vegetation.The evergreen vegetation distributed more widely in the range of 1.0?8.0 compared to 1.3?5.4 of deciduous vegetation.2)The LAI index of urban green space was significantly affected by tree characteristics.The effects of tree height,diameter at breast height and crown width on leaf area index will be different with the change of types.The leaf area index of trees increased with tree height,diameter at breast height and crown width,and the leaf area index of shrubs has a negative correlation with plant height and crown width.The leaf area index of evergreen and deciduous vegetation is basically consistent with the characteristics of vegetation itself,and increases with tree height,diameter at breast height and crown width.There are also significant differences in the relationship between the leaf area index and its own characteristics.The change of leaf area index shows different trends in different tree types.3)The LAI index of urban green space is significant because of the change of light direction.Since the change in light direction mainly produces different illumination intensity,which causes differences in the growth conditions of the vegetation,so as influences the size of the leaf area index.The leaf area index of the tree and shrub vegetation in the south are the maximum,3.11 and 4.28 respectively,while the tree vegetation index in the east leaf area index is the smallest 2.97,and the shrub vegetation in the north is the minimum 4.07.The evergreen vegetation has the largest leaf area index(3.89)in the west and the smallest(3.7)in the east,while the deciduous vegetation has the largest leaf area index in the south(3.52)and the smallest in the north(3.29).4)The LAI index of urban green space varies with the seasons.The changes of temperature factors in the same vegetation in different seasons also showed different trends in leaf area index.Both of the tree and shrub have the minimum leaf area index of 3.29 and 2.63 respectively in spring,followed by winter;the tree vegetation reached up to the maximum(4.43)in summer,and the shrub vegetation reached up to the maximum in autumn(4.40).In addition,the difference between the autumn leaf area index and the spring and winter seasons of tree vegetation is significantly smaller than that of shrub vegetation.The evergreen and deciduous vegetation also have the smallest leaf area index of 2.73 and 3.20 in the spring,respectively.The deciduous vegetation has the same minimum leaf area index in winter and spring;The evergreen vegetation has the largest leaf area index of 4.51 in autumn,while the deciduous vegetation has the largest leaf area index of 4.54 in summer;The difference between the autumn leaf area index of evergreen vegetation and spring and winter is significantly higher than that of deciduous vegetation.By investigating the leaf area index of city parks,we can accurately understand the overall application characteristics of vegetation trees in city parks and establish the correlation between leaf area index and its own characteristics.In addition,through the change of the effects of environmental factors such as light and temperature on the leaf area index,the law of the influence of environmental factors on the landscape vegetation is further explored,and the selection of tree species and the configuration of plant communities in the overall urban green space planning and construction will be better developed.The ecological benefits and greening effects of green land are of important guiding significance.