Physiological response of Betula platyphylla leaves to fire and the restoration after fire

In this study,the changes of leaf physiological metabolism and the recovery of fire treatments were studied. Using 6-year-old saplings of Betula platyphylla as the test materials,different parts(all the trunk and under branches of trunk) were fired under same fire intensity and fire time. The results showed that the leaves produced by lipid peroxidation and the relative water content (RWC),chlorophyll content and chlorophyll fluorescence parameters(Fv / Fo,F'v / F'm,qP,ETR)significantly decreased in 0-10 days after fire treatment. The antioxidant enzyme SOD activity,POD activity,proline content and soluble sugar content significantly increased,which showed the fire resistance of B. platyphylla. After 10 days of fire treatment,the damage began to recover and the content of MDA began to decline,the RWC, chlorophyll content and chlorophyll fluorescence parameter(Fv / Fo,F'v / F'm,qP,ETR) began to rise and reached control levels after 30 days of fire treatment. These showed equal compensation effects,and the content of MDA decreased to control level. The chlorophyll content and chlorophyll fluorescence parameters(Fv / Fo,F'v / F'm,qP,ETR)were significantly higher than control after 40 days of fire treatment,which showed super compensation effects. Increased leaf photosynthetic capacity repaired the damage by fire of B. platyphylla. The proline content and SOD activity were significantly higher than control,which was a delayed reaction and was beneficial for the growth of trees under stress.