Effects Of Post-Fire On Seedlings Growth Of Pinus Yunnanensis

As an ancient and recurring interfering factor,forest fire had brought huge losses to human property safety and natural resources each year.The plateau in central Yunnan is a high-incidence fire area.Forest fires occured frequently in coniferous forest areas,and fires occured mainly in Pinus yunnanensis and its variant mixed forests.Therefore,it is particularly important to study the fire adaptation of P.yunnanensis.However,too little research had been done on the impact of post-fire on the growth of P.yunnanensis seedlings.In this study,we selected the seeds of P.yunnanensis var.pygmaea which lives in Qinfeng town,Lufeng county,Chuxiong prefecture where had frequently forest fire occured as our experimental materials.Differences of seeds germination,growth index,biochemical index,chlorophyll fluorescence parameter index of leaves in the 100 d and one-year seedlings,which the seeds were baked in different temperature before geimination were compared.Differences of growth of seedlings among different high temperature treatment groups were analyzed.The effect of high temperature experienced before germination on growth of seedlings of P.yunnanensis var.pygmae was discussed.Differences of growth index,leaf chlorophyll fluorescence parameters in the 100 d and one-year seedlings among ash or no ash groups and different amounts of nutrient soil groups were compared.Differences of growth in the seedlings among different cultivation substrate groups were compared.The effect of ash produced during post-fire on growth of seedlings of P.yunnanensis var.pygmae was discussed.The density,height and stem of P.yunnanensis at three growth stages in canopy,surface fire and no fire habitats were measured.The effect of forest fire of P.yunnanensis was discussed.The results were fliilwed:(1)The seeds of P.yunnanensis var.pygmaea had thermal shock effect after a short period of 90? high temperature treatment before germination.(2)After the seeds of P.yunnanensis var.pygmaea had experienced a short period of high temperature growth,stress resistance and photosynthetic capacity of seedlings were promoted.However,the promotion of germination and growth,growth indicators and stress resistance and photosynthetic capacity indicators of seedlings was not correlation.Further studies were needed to verify whether the seeds experience an appropriate high temperature would promote the growth of seedlings.Excessive temperatures would cause some of the seeds in the cone to die and the seeds germination rate to decline.However,it would not damage the growth of seedlings that seeds can germinate.(3)Our study did not find significant promotion of ash on the growth of P.yunnanensis var.pygmaea seedlings.However,nutritious soil had a significant role in promoting.This may be because the seedlings growth time in this study was too short to show the effect of ash on seedling growth.(4)The growth potential of P.yunnanensis seedlings regenerated after canopy fire was not significantly different from that of the unfired one in the first year of growth.The growth potential in the second year was significantly higher than that in unfired ones.The results of previous research and ours showed the thermal shock on seeds of P.yunnanensis var.pygmaea.This study did not find that high temperature and ash could promote the growth of seedlings of P.yunnanensis var.pygmaea significantly.However,it was found that even if the temperature was too high,the germination rate of P.yunnanensis var.pygmaea seeds was reduced,but it did not affect the seedlings growth after seeds germination.P.yunnanensis could regenerate after the post-fire.