Study On Density Control Of Pinus Tabulaeformis Building Timber Plantation During The Whole Life Cycle

There is a suitable area for Pinus tabulaeformis plantation in Huangtuliangzi Town,Pingquan,Hebei,where the forest structure is unreasonable,the cultivation purpose is single,the management is extensive,and some forest areas fail to update the density control measures in a timely manner,resulting in low production.Therefore,this paper focuses on the construction of density control measures system of Pinus tabulaeformis building timber plantation during the whole life cycle,adopting the space-time intergenerational method,specifically taking Pinus tabulaeformis plantation in Pingquan Hebei as the research object,focusing on study on dynamic regulation techniques of whole-life cycle density of Pinus tabulaeformis stands on three sites and at different growth stages.Analyzed the tree shape,productivity and trunk biomass allocation of Pinus tabulaeformis plantations at different sites,different forest ages,and different densities,at the same time,intend to reveal the density regularity of Pinus tabulaeformis plantations;carried out reasonable density experiments and formulated canopy areas and density index table of different diameters;formulated a density management map which suitable for Pinus tabulaeformis building timber plantation in North China,and determined the optimal cutting age for the site most suitable for cultivating Pinus tabulaeformis building timber,combined with the output of building material species.The aim is to achieve refined cultivation and sustainable forest management of Pinus tabulaeformis building timber plantation during the whole life cycle,and to provide refined references for the formulation of forest management measures in forest farms and other related departments.The innovation is that the specifications of Pinus tabulaeformis building timber plantation in Hebei are compiled for the first time,and density adjustment measures in the main site type of Pinus tabulaeformis building timber forest during the whole life-cycle are proposed,the gap in the research at this stage is filled.The main conclusions are as follows:(1)Compared with the middle soil on sunny slope,stands in the middle and thick soil on shady slope have a lower overall branching rate,a longer living crown height,a larger height-to-diameter ratio,and the tree shape of the Pinus tabulaeformis forest in thick soil on shady slope is the best.(2)At the same age,the theoretical density of pine forest is the highest in middle soil on sunny slope,followed by the middle soil on shady slope,and the smallest the thick soil on shady slope.For the same diameter scale,the reasonable management density of forest stands showed that the middle soil on sunny slope <the middle soil on shady slope <the thick soil on shady slope.When the diameter step is less than 18 cm,as the diameter step increases,the reasonable management density of Pinus tabulaeformis stands in middle soil on sunny slope soil,middle soil on shady slope and thick soil on shady slope gradually decreases.Under site conditions,the reasonable management density of Pinus tabulaeformis plantation is basically the same,about 500 plants per hectare.(3)The initial planting density of Pinus tabulaeformis stands in middle soil on sunny slope is 3000 to 3300 plants per hectare.Quantitative lower thinning according to the number of plants,specifically,thinning starts at 10 years and the thinning intensity is 12%,The second and third thinnings are carried out at 20% and 25% intensities at 15 and 25 years respectively,a total of 3 times thinnings,with intervals of 5 and 10 years.The plant density is 1650 plants per hectare at the mature age to allow the trees to grow naturally and maintain good tree shape.The shape is high,and the biomass is transferred to the trunk more.The cutting height is 9 to 11 meters,the average single plant volume is 0.0697 cubic meters,and the volume of each hectare is 115 cubic meters.It is used to cultivate small-diameter building timber,the specification is 16 cm.(4)The initial planting density of Pinus tabulaeformis stands in middle soil on shady slope is 2700 to 3000 plants per hectare.Quantitative lower thinning according to the number of plants,20% and 30% intensity as first and second thinning at 9 years and 19 years,a total of 2 times thinnings,with an interval of 10 years.Retain 1500 plants per hectare at mature age to obtain a better tree shape.The tree height is 9 to 11 meters,and the average single plant volume is 0.0920 cubic meters,and the volume of each hectare is 138 cubic meters.It is used to cultivate medium-diameter building timber with the size of 16 to 22 cm.The initial planting density was 2200 to 2500 plants per hectare,thinning started at 9 years,the first thinning intensity was 20%,and the second and third thinning are carried out at 25% and 30% intensities in 17 and 27 years respectively,a total of 3 times thinnings The interval is 8 years and 10 years respectively,the retention density is 1000 plants per hectare,the cutting height is 11 to 13 meters,the average single plant volume is 0.1450 cubic meters,and accumulation is 145 cubic meters per hactare,used to cultivate large-diameter timber,the specification is greater than 22 cm.(5)The initial planting density of Pinus tabulaeformis stands in thick soil on shady slope is 2000 to 2300 plants per hectare.Quantitative lower thinning according to the number of plants,specifically,the intensity is 20% and 30% at 7 and 15 years as the first thinning and the second thinning,a total of 2 times thinnings,the interval is 8 years,the optimal cutting age is 47 years,the density of the number of retained plants is 1200 plants per hectare,the height of the trees in the felling period is 11 to 13 meters,and the average of the retained trees.The volume of each plant is 0.1375 cubic meters,and the accumulation of each hectare is 165 cubic meters.It is used to cultivate medium-diameter building timber.The specification is 16 to 22 cm.The initial planting density was 1000 to 1200 plants per hectare,thinning started at 7 years,the first thinning intensity is 20%,and the second and third thinnings are carried out at 20% and 25% intensities in 13 and 23 years respectively.The interval is 6 years and 10 years respectively,the retention density is 530 plants per hectare to obtain a better tree shape,at this time the trunk biomass proportion is the best,the optimal cutting age is 53 to 55 years,and the cutting height is 13 to 15 meters,with an average tree volume of 0.2245 cubic meters per tree,and accumulation with 119 cubic meters per hectare.It is used to cultivate large-diameter timber with a size of more than 22 cm.