Characteristics Of Seed Bank And Natural Regeneration Of Pinus Sylvestris Var.Mongolica Plantation In Southern Horqin Sandy Land

Pinus sylvestris var.mongolica originally distributes in Daxinganling area and Hulunbuir sandy land.It is a geographic variation of Scots pine?Pinus sylvestris L.?in our country,which has excellent features such as cold resistance,drought resistance and relatively fast growth.It is the main tree specie for windbreak and sand fixation,soil and water conservation farmland and meadows protection and timber forest in northern semi-arid sand area of our country.In 1955,Pinus sylvestris var.mongolica was successfully introduced to Zhanggutai,Zhangwu county of the southern margin in Horqinsandy land,the artificial afforestation technology rapidly popularized in three north areas,making it a pioneer species of sand in our country.At present,the first generation of Pinus sylvestris var.mongolica in Zhanggutai and other parts of the earliest construction artificial projects most has entered a stage of update,and give priority to artificial regeneration,but there is less exploration and practice artificial of natural regeneration of Pinus sylvestris var.mongolica plantation.In Hulunbeir and Daxinganling,origin of Pinus sylvestris var.mongolica is a tree species with very strong natural regeneration ability,but in the introduction,its natural regeneration is very difficult.Therefore,in order to seek effective measures to ensure and promote the natural regeneration of mongolica plantation,proved and analyzed the main factors influencing the sand mongolica plantation natural regeneration,safeguard the Pinus sylvestris var.mongolica plantation to gain benefit,long-term stability,reduce the cost of the artificial afforestation and play a bigger role in ecological,it is a universal concern of the masses of forestry scientific research personnel.In this study,on the basis of population ecology,forest manager,statistics and multidisciplinary theory,on point of view the characteristics of Pinus sylvestris var.mongolica plantation soil seed bank composition and distribution of natural regeneration,through a variety of means of observation,analytical the characteristics of soil seed banks and the natural regeneration of Pinus sylvestris var.mongolica plantation,puts forward some factors that influence the natural regeneration of Pinus sylvestris var.mongolica plantation.To provide theoretical basis and technological support for vegetation restoration,fragile ecosystem protection and prevention and control of desertification on sandy land.The natural regeneration of Pinus sylvestris var.mongolica plantation was influenced by the morphological structure of the single plant,environmental factors,interaction and interference between biology.There were many factors influence the natural regeneration such as the age class,viability,crown diameter,tree height of the seed tree,stand condition and activity of seeds.Ecology method was used to investigate and analysis the characteristics of natural regeneration of Pinus sylvestris var.mongolica plantation,the main research results include the following aspects:?1?By research of the cone regeneration of Pinus sylvestris var.mongolica plantation in southern Horqin sandy land showed that young trees begin seed in 13¹5a and 17a in common,bumper seed harvest year comes every 3 to 5 years.The same forest canopy density,through the analysis of variance,the difference of cone is remarkable?P<0.05?,characterized by:cone length,significant difference was found in young forest and half-mature forest,no significant difference of half-mature forest and mature forest;Cone width,significant difference was found in young forest and half-mature forest,no significant difference of half-mature forest and mature forest;Mature seed,significant difference was found in young forest and mature forest,no significant differences in young forest and mature forest;Empty seed,significant difference was found in young forest and mature forest,no significant differences in young forest and mature forest;1000-grain weight,no significant difference was found.The results showed that in young forest the cone was larger,but mature cone was less.In half-mature forest,mature cone was in largest proportion,seed quality was good.In mature forest,empty seed was in largest proportion,1000-grain weight was light,seed quality was poor.Cone size and quality of Pinus sylvestris var.mongolica were effected by climate factors,individual growth characteristics,crown density and many other factors.?2?The space distribution of seed bank Pinus sylvestris var.mongolica plantation in southern Horqin sandy land was mainly presented mother tree trunk as the center aggregation distribution,and gradually spread from the forests to the gap of forests,along with the increase of the distance,the parent soil seed banks in complete seed grain number was gradually reduced.Most of seeds disbute in the litter layer and 0⁵ cm soil layer.Through the surver,in young forest,half-mature forest and mature forest,the amount of intact seeds occupy 20.54%,18.01%,30.65%of surveyed seeds,respectively,average density is 98·m^-2,98·m^-2,84·m^-2,respectively.Half-mature forest has the largest intact seeds amount and density.?3?The natural regeneration of Pinus sylvestris var.mongolica plantation in southern Horqinsandy land was mainly in forest gaps,density of 428⁶167·hm^-2,followed by regeneration of single plant and regeneration on edges of a forest.The regeneration of single plant region was a fan-shaped area,which had a certain distance from the seed tree in the north by east.The region was also the crown canopy projection trajectory of the seed tree after 12:00,roughly the range of 50¹20°.The main condition for the regeneration on edges of a forest is the edge extension zone,density of regeneration on edges of a forest was400⁷67·hm^-2.The regeneration of single plant,regeneration in forest gaps and regeneration on edges of a forest have close correlation with the crown canopy projection trajectory.The seed tree canopy projection provided refuge for natural regeneration seedlings.The natural regeneration did not have continuity,there has more seedlings in the years which had more rainfall.When the forest canopy density was greater than 0.6,there would be no natural regeneration seedlings.So forest thinning was necessory for natural regeneration,adjust forest canopy density below to 0.6,providing necessary conditions for natural regeneration.?4?East slope,northwest slope,northeast slope had the best regeneration for slope aspect and slope position regeneration.There were more regeneration seedlings in the middle and upper abdomen of the slope as the influence of environmental factors such as emperature,humidity,illumination and sand bed thickness,along with the change of environmental gradient causing the corresponding distribution pattern generation.?5?The experiment of fertigation and watering for mother tree of Pinus sylvestris var.mongolica plantation in southern Horqinsandy land,the result showed that fertigation and watering increase the coning bearing;Site preparation helped natural regeneration,improved the density of the natural regeneration and seedling drought resistance ability;Different measures of protective cover test to seedling,best winter survival rate was the white sand covering,and easy to operate,it was the best cover measure;Site preparation increased the capability of seedling drought resistance,helped to improve natural regeneration density;Large winter snow thickness helped Pinus sylvestris var.mongolica seedlings wintering safely,it is conducive to natural regeneration.?6?The natural regeneration of Pinus sylvestris var.mongolica plantation in southern Horqinsandy land was effected by the plant morphological structure,environmental factors,the influence of the interaction between biological and interference,age level,life force,crown breadth,tree height and stand condition,activity of seeds of mother tree were all effective factors.Environmental factors such as temperature,humidity,illumination and microbial environment,thickness of the sand bed,along with the change of environmental gradient causing the corresponding distribution pattern generation.It was worth mentioning that natural regeneration of Pinus sylvestris var.mongolica plantation was greatly influenced by light intensity,regeneration seedlings can survive under shade environment,mother tree shade function determines its germination,survival and distribution.