Performance Evaluation Of Thinning Of Poplar Plantation In Eastern Henan Plain

Forest is the most valuable resource in the world,tending thinning on the forest stand growth,stand structure,the total harvest,biodiversity,which have an indispensable role.There are many hot-pots on tending thinning,and it has been proved that tending thinning has a positive effect on improving the survival rate of trees,improving the quality of stands and increasing the growth of trees.Based on a large number of relevant foreign and domestic literature,this paper selected the poplar plantation of civil rights forest in Shangqiu civil area of Eastern Henan Province as the research object,and investigated three different thinning intensities(Level I,Level II,Level III)of different age(5 to 8 years old poplar)based on the standard data.The effects of different thinning intensities on the height,DBH,crown and volume growth of poplar trees in different age groups from 2011 to 2016 were analyzed in detail.Meanwhile,the effects of different thinning intensities on soil organic matter,total nitrogen,and the content of available potassium and available phosphorus were measured.Finally,according to the results of the study,this paper provided suggestions for the actual management and production of forest.The main results of this paper are as follows:(1)The greater the thinning intensity,the greater the DBH growth;the greater the thinning intensity,the greater the volume growth;the greater thinning intensity,the denser of the stands,the tree height growth did not directly be affected by thinning intensities;the greater thinning intensities,the greater the crown growth.(2)Based on the observed results,the results of different thinning intensities were based on volume,tree height,crown width and DBH growth rate are as follows: Level III thinning intensity> Level II thinning intensity> I level thinning intensity.(3)7-year-old poplar was the best target for the first thinning,the first thinning intensity for the III level when the volume,tree height,crown width,DBH growth reached the maximum,followed by Level III thinning intensity.And the growth rate of the6-year-old poplar was the highest in the second-order volume,the height of the tree height,the crown width and the DBH growth rate were the maximum,and then the third-The yield of 5-year-old poplar was the highest,and the height of crown height,crown width and DBH was the highest,and then the second-order crop yield was maximized for two consecutive years.The first thinning intensity is the volume of III,the height of tree height,crown width and DBH growth rate are the maximum,and then the growth rate is maximized when the intensity is Level III or three years.(4)The number of species of undergrowth plants in poplar plantation increased as the increased of density,however,decreased with the increment of density when the density reached 396 plants / hm2.(5)The organic matter,total nitrogen,hydrolyzed nitrogen,total phosphorus and available phosphorus of poplar plantation showed a tendency that the difference was significant(P <0.05)as the decline of soil depth..(6)In the 9 different density models,264 plants / hm~2(spacing of 3 × 10m)had the lowest soil nutrient content;398 plants / hm~2(spacing of 3 × 8m)had the highest soil nutrient content,and there was no significant difference between soil nutrient contents under other densities.