Influence Factors of Natural Regeneration Seedlings for Pinus sylvestris var.mongolica on Hulunbuir Sandyland

Traits of natural regeneration seedlings of natural forest of Pinus sylvestris var.mongolica on Hulunbuir sandyland were studied.Result shows that:number and age structure of natural regeneration seedlings significantly different with different densities of seed trees;age structure of natural regeneration seedlings for Pinus sylvestris var.mongolica has obvious discontinuity in time;densities of natural regeneration seedlings are obviously different due to differences in forest types.Open woodland(30-year-old tree),the density of average regeneration seedlings are 13 trees per 2 500 m2;density of the average regeneration seedlings in the burned area are 28.5 trees per 600 m2;average density of regeneration seedlings for individual Pinus sylvestris var.mongolica in the sample plots are 118.8 trees per 600 m2.Reserved density mean annual precipitation of natural regeneration seedlings with different ages have significant or very significant relationship;density of natural regeneration seedlings in the study area decrease with the increase of canopy density.