Among them, there was an extremely significant negative correlation between specific leaf area and chlorophyll content, leaf dry matter content, leaf tissue density, stomatal density ( P < 0.01), but showed an extremely significant positive correlation with stomatal size ( P < 0.01).
On the whole, the correlation among traits showed an increasing trend when the temperature was moderate(T1), but a decreasing trend when the temperature was too high (T2).
This indicated that the leaf functional traits showed a certain trade-off strategy in order to adapt to the urban environment, which verified the existence of the leaf economics spectrum in the urban forest ecosystem. Effect of warming on the relationship between plant leaf functional traits As shown in Table 1 , the correlation between functional traits of plant leaves showed a trend of increasing first and then decreasing under different warming treatments.
This indicated that the warming effect of the warming group was highly significant (Fig. 6 ).