The Characteristics Of Seedling Regeneration And Its Response To Soil Nutrients In The Burned Area Of Larix Gmelinii Forest

Forest fire is one of the disturbance factors of forest ecosystem degradation in Daxing’an forest area.It is of great theoretical and practical significance to study the characteristics of soil and vegetation restoration in burned area.In this paper,the renewal,spatial distribution pattern and soil nutrient variation characteristics of fire-disrupting seedlings with different intensity were studied by the fire-fire burning sites in 2010 of Alongshan Forestry Bureau in Daxing’an Inner Mongolia.In addition,the relationship between seedling renewal and soil nutrients was analyzed.The main results are as follows:(1)The regeneration density of seedlings in burn sites with different intensities was different.M>H>C>L,and the spatial distribution pattern of seedlings was generally clustered according to four aggregation indexes including C0,GI,m*and I0.The aggregation intensity of seedlings with moderate fire interference was the largest,followed by severe fire interference,and the smallest was mild.The spatial distribution pattern of larch seedlings in xing’an was aggregation distribution,with the most moderate aggregation intensity and the least severe aggregation intensity.(2)The regeneration effect of vegetation seedlings in different intensity burning sites was different,the moderate fire disturbance seedling regeneration effect was the best,the maximum regeneration index was 0.73,the mild vegetation seedling regeneration effect was the worst,and the minimum regeneration index was 0.43.As far as the regeneration seedlings of Larix gmelinii are concerned,the mild fire disturbance renewal effect is the best,the maximum renewal index is 0.74,the moderate is the second,the severe renewal effect is the worst,and the renewal index is 0.49.It can be seen that mild fire interference is beneficial to the renewal of larch seedlings in Xingan.(3)The contents of organic matter,whole N and whole K in the litter layer of burning ground decreased significantly,and the contents of organic matter and whole P increased with the increase of intensity of fire disturbance.The soil layer also changed obviously after fire disturbance.When the soil depth was 0-20cm,the pH value and effective P content were lower than those of the opposite soil.The pH value of soil depth in 20-40cm had no obvious change,but the content of organic matter,whole N and whole K increased obviously,and the content of each index was 0-20cm higher than 20-40cm.(4)There was significant correlation between seedling regeneration and soil nutrients.principal component analysis(PCA)was used to further show that the seedling renewal index was positively correlated with the organic matter,total nitrogen and total potassium index in litter layer and the available phosphorus,pH value and available nitrogen index in soil depth of 0-20cm.The main nutrient factors affecting seedling regeneration after fire disturbance were available phosphorus and pH in soil depth of 0-20cm.The main nutrient factors affecting seedling regeneration of Larix gmelinii were total nitrogen and organic matter in litter layer.