A Study On Post-fire Natural Regeneration Of Pinus Vunnanensis

We studied the pre-and post-fire clump density,branch density,height and basal diameter of original and regenerative plants of Pinus yunnanensis var.pygmeae in three sample plots of different slope at Tuanjie and Qinfeng burned blank.We analyzed the main factors influencing the damage of P.var.pygmeae,compared the difference of post-fire resprouting and seeding,discussed the effect factors of different regeneration patterns.We also studied the pre-fire stem density,height,DBH of P.yunnanensis and the post-fire seeding density,bum height,coverage of other plants in three sample plot of different fire severity of Luxichong burned blank.We analyzed the main factors influencing the damage of P.yunnanensis and discussed the effect factors of seeding density.The results showed:(1)Crown fire occurred all of plots at Tuanjie and Qinfeng.There were two types of damages:the whole plant died and the aboveground died.The whole plant mortality was significant positive correlation with clump density and branches density.And there was no significant correlation between pre-fire height and basal diameter of plants.The damaged of plants was determined by the fuel loadings.There was a significant positive correlation between the whole plant mortality and the fuel loadings.(2)There were two regeneration patterns at Tuanjie and Qinfeng plots:resprouting and seeding.And there was a significant difference in regeneration efficiency of resprouting and seeding.The difference of resprouting and seeding density in plots of the same slope in Tuanjie was not significant,but the height growth and basal diameter of resprouting were significantly greater than seeding.The seeding density were significantly greater than resprouting density in plots of the same slope in Qinfeng,but the difference of height growth and basal diameter was not significant.(3)The resprouting strategy was excepted in Tuanjie plots and seeding strategy is excepted in Qinfeng plots.The selection of seeding and resprouting was affected by the whole plant mortality P.yunnanensis var.Pygmeae.There was a significant positive correlation between the seeding density and the whole plant mortality in Tuanjie and Qinfeng plots.And There was a significant negative correlation between the resprouting density and the whole plant mortality.(4)P.yunnanensis was different from P.yunnanensis var.Pygmeae.Some occurred crown fire and the others occurred surface fire in the plots.There were two kinds of situations in the plots of surface fire:one was the canopy needles retained and continue to grow,another was the canopy needles died.The whole plant mortality of P.yunnanensis was determined by the burn height.And had no significant correlation with pre-fire stem density,height and DBH of plants.(5)There was a significant difference in seeding density of P.yunnanensis in the Luxichong plots of three different fire severity.The seeding density was affected by the fire intensity.The seeding density is low in the plots with high fire intensity,oppositely the seeding density is high in the plots with low fire intensity.The seeding density was also negatively correlated with the coverage of other plants in the plots.