Spatial pattern of post-fire regeneration of Pinus sylvestris var.mongolica forest in Hulun Buir Sandland,northeastern China

Fire is one of the main driving factors of regeneration of natural Pinus sylvestris var.mongolica forests.This research conducted in 1 hm~2 P.sylvestris var.mongolica forest with 12 years of post-fire,emphasized on the spatial pattern and interactions of P.sylvestris var.mongolica adults and saplings(seedlings) and the invaded broadleaved trees.The results showed that after surface fire disturbance,the spatial pattern of the existing P.sylvestris var.mongolica adults was regular at smaller scale(0-625 cm)and larger scale(1 150(-)5 000 cm),and random at intermediate scale(750-1 125 cm).Many relatively even forest gaps formed,which provided suitable habitats for conspecific seed germination and other broadleaved tree species colonization.These saplings(seedlings) and broadleaved trees had significantly aggregating trend within forest gaps.Following the restoration of post-fire stand,negative associations between P.sylvestris var.mongolica adults and conspecific saplings(seedlings),as well as broadleaved trees were reflected with bivariate K function analysis,implying that intraspecific(interspecific) competition appeared in the post-fire stand,and the colonized broadleaved trees may die and natural thinning occurred for clustering P.sylvestris var.mongolica saplings(seedlings),the final pattern for saplings(seedlings) may,similar to conspecific adults,be more regular.These results will be helpful to better understand post-fire spatial pattern and regeneration process of natural P.sylvestris var.mongolica forest,and to make sound decisions for the sustainable natural forest management.