Abstract: Functional traits are important foundation for the ecological functions of plants. Functional diversity based on functional traits is an important indicator for assessing biodiversity and plant functions. With the investigation data of 587 treeshrub plots and 1779 herb plots in the builtup area of Shenzhen, we analyzed plant community types and their functional traits, compared functional diversity of plants from the perspective of four ecological functions, including dust retention, noise attenuation, temperature reduction and humidity increase, and biodiversity conservation. The results of TWINSPAN classification showed that among the 41 tree-shrub community types and 54 herb community types, there were nine tree-shrub community types with ≥10 plots and 15 herb community types with ≥30 plots. The analyses on indicator species and dominant species in communities by plots showed that functional traits of trees and shrubs were commonly broadleaf (100%), evergreen (79.47%), small crowns (93.04%), nonNfixing plants (90.54%), leaf glabrous or hairless (76.95%), and herb plants were mostly small fruit (97.07%), dried fruit (91.33%), and nonNfixing plants (93.9%). The orders of functional diversities for different types of green space were roughly opposite for treeshrub and herb. The highest functional diversities of dust retention, noise attenuation, temperature reduction andhumidity increase and biodiversity conservation for trees all presented in park green space. For shrubs, the highest values were found in residential zone, park, road and park green space. For herbs, the highest values of the first three functions were found in wasteland, and that of the last one was in residential green space. Community structures of wasteland were different with other green space. Our results suggest that the construction of green space in the builtup area of Shenzhen should pay more attention to functional diversity of residential and institutional green space. This study provides reference for the evaluation of urban vegetation function, planning and design of green space, selection of plant species, urban biodiversity conservation, and ecosystem service improvement.

Key words: seasonal variation., altitudinal gradient, tree seedlings