The rapidity of stomatal response to dynamic irradiance is one of important factors affecting leaf water use efficiency. In order to explore the physiological mechanism of water use efficiency variation in trees from different succession stages, we studied the lightinduced stomatal conductance (g_s) dynamics and their relation with stomatal traits and leaf longterm water use efficiency in seedplanted seedlings of three species (early succession stage species: Populus davidiana and Betula platyphylla, and late succession species Quercus liaotungensis) native to Huanglong Mountain forest region using a pot experiment. Results showed that, (1) time constant during stomatal opening (K_i) in P. davidiana and B. platyphylla was shorter than that in Q. liaotungensis, but time constant during stomatal closing (K_d) in P. davidiana and B. platyphylla was longer than that in Q. liaotungensis, reflecting that stomata open faster in P. davidiana and B. platyphylla, and close faster in Q. liaotungensis. P. davidiana and B. platyphylla had larger g_s response amplitude than Q. liaotungensis during stomatal opening, and P. davidiana had larger g_s response amplitude than Q. liaotungensis during stomatal closing. (2) Q. liaotungensis had the largest stomatal density, smallest stomatal size and biggest stomatal index among three species, stomatal traits in Q. liaotungensis could not explain its slower stomatal opening response. (3) P. davidiana and B. platyphylla had higher photosynthetic rate, maximum carboxylation velocity, maximum electron transport rate, longterm water use efficiency indicated by leaf δ¹³C exhibited as P. davidiana > B. platyphylla > Q. liaotungensis. The results show that higher water use efficiency in P. davidiana and B. platyphylla was partly attributed to their rapid stomatal opening, while rapid stomatal closing in the late succession species Q. liaotungensis did not enhance its water use efficiency, and the longterm water use efficiency is lower than that of P. davidiana and B. platyphylla, which may be related to the slow stomatal opening of Q. liaotungensis limiting its photosynthetic rate.