Abstract: The effects of drought stress and rehydration on photosynthetic characteristics and antioxidant enzyme activities of needles and bark chlorenchyma of Korean pine were studied. The results showed that the total chlorophyll content and chlorophyll a/b of needles and bark chlorenchyma decreased significantly under drought stress, reducing the PSII antenna to capture light energy and thus the risk of photoinhibition. The main reason for restricting net photosynthetic rate (P_n) of needles was nonstomatal limitation and the main reason for restricting P_n of bark chlorenchyma was stomatal limitation. Nonphotochemical quenching (NPQ) of needles and bark chlorenchyma were significantly increased under drought stress, indicating that thermal dissipation is an important photoprotection mechanism. Malondialdehyde (MDA) contents in needles and bark chlorenchyma were significantly increased under drought stress, resulting in oxidative stress. Increased SOD activity played an active role in drought stress defense of pine. After rehydration, P_n of needles and bark chlorenchyma recovered to the level of the control. Chlorophyll fluorescence parameters and antioxidant enzyme activities also recovered to varying degrees. These results suggest that needles and bark chlorenchyma of Korean pine can stabilize the photosynthetic apparatus function by enhancement of thermal dissipation and antioxidant enzyme activity, and that Korean pine has a good recovery after rehydration and strong adaptability to drought stress.

Key words: Key words: buffering zone, Ecopath with Ecosim (EWE) model, system features, trophic level, wetland ecosystem