Abstract: The spatial features and attribute data of urban forests in Shenyang arboretum were acquired by using aerial photographs and field investigation．After systemic and quantitative analysis of the species composition an d spatial
distribution pattern of urban forest community based on geographic information system (GIS)，the foHowing results were achieved：1)the vegetation in the arbo retum was rich and in a good condition．Phellodendron amuren se, Robinia pseudoacacia，and Ulmus pumila were the main species according to their abundant individuals and relative dominan ce．The spatial distribution pattern of this vegetation indicated that it was in a growing level and in the best state for ecological benefits；2)the tree species relative dominance based on veg etation quantity had no distinct relationship with the species abundance．and the species having abundant individuals might have a low relative dominance；and 3)the curve displayed in the relationship diagram between tree individuals and tree height showed ascending and protruding．W ith the increment of tree height class，the individuals were unchanged neady at the beginning，but when the height was more than 12 m，the individuals red uced distinctly，an d the curve displayed a quickly declined trend．The relationship between tree individuals and tree diameter at the breast height(DBH)showed the same result.

Key words: photoperiod, dormancy induction, peach, photosystem, chlorophyll fluorescence transient kinetics.