Effects Of Thinning On Seeding Regeneration And Soil Factors Of Quercus Acutissima In Qiaoshan Forest Area

In order to investigate the effects of thinning on seedling regeneration and soil physical and chemical properties of secondary forests of Q.acutissima,the secondary forests of Q.acutissima in Shuanglong Forest Farm of Qiaoshan Forests under different thinning intensity(un-cutting-control,thinning 15%-light thinning,thinning 25%-medium thinning,thinning 35%-heavy thinning)were selected as the research object.The number and growth dynamics of seedlings,soil physical and chemical properties and litter characteristics were investigated,and the correlation between seedling regeneration index and soil physical and chemical properties was analyzed.The effects of thinning on the seedling regeneration and soil physical and chemical properties of the secondary forest of Q.acutissima in the Qiaoshan forest area were provided,which provided a theoretical basis for improving regeneration ability and the population recovery of the secondary forest of Q.acutissima in the Qiaoshan forest area.1.Tending thinning increased the number of Q.acutissima seedlings and promoted the growth of Q.acutissima seedlings: the number of Q.acutissima seedlings varied significantly under the four thinning intensity,and the number of Q.acutissima seedlings increased with the increase of thinning intensity;the number and leaves of Q.acutissima seedlings area,number of branches,length of branches,total root length,number of root tips,total root volume,root surface area and root length increased with increasing thinning intensity,and were the largest under heavy thinning intensity.The specific performance is:heavy thinning > medium thinning > light thinning > control;the average diameter of roots decreases with the increase of thinning intensity,and the average diameter of roots is the smallest under severe thinning intensity.2.Thinning has significant effects on biomass allocation of Q.acutissima seedlings:thinning can significantly increase the roots,branches,leaf biomass,and the effect of heavy thinning intensity is the largest;The proportion of leaf biomass and branch biomass showed a trend of decreasing with the increase of thinning intensity,and the smallest under heavy thinning intensity,and the proportion of root biomass increases with the increase of thinning intensity.3.Thinning can significantly affect soil physical and chemical properties and litter characteristics: thinning can significantly increase soil water content,porosity,organic matter,total nitrogen,available nitrogen,available phosphorus and available potassium,while reducing soil bulk density and p H,and improve soil nutrient and water contents,and the effect of heavy thinning intensity is the largest;With the decomposition time going by,the weight loss of litter changes in an "M" shape;Thinning can accelerate the decomposition of litter,and the weight loss rate of litter is the highest under heavy thinning intensity.During the decomposition of litter,the content of total nitrogen and total phosphorus was “enriched-released”,and the total potassium content was in accordance with the “direct release” mode.With the increase of thinning intensity,the annual return of nitrogen,phosphorus and potassium in litter both increased,and the annual return of litter nutrients under heavy thinning intensity was the largest.4.Tending thinning had significant effects on seedling regeneration index: with the increase of thinning intensity,the regeneration index of Q.acutissima seedlings increased gradually,and the severe thinning was the largest.The index of light thinning,medium thinning and heavy thinning increased by 8.7%,24.2% and 33.7% respectively compared with the control.5.The correlation between soil physical and chemical properties and seedling regeneration index was strong: the seedling regeneration index was negatively correlated with soil bulk density and p H,and positively correlated with soil water content,organic matter,alkali nitrogen,available phosphorus and litter reserves.The correlation between seedling renewal index and soil physical and chemical properties in 0-20 cm soil layer was generally stronger than that in 20-40 cm soil layer;soil alkaline nitrogen,organic matter were the main indicators affecting the regeneration of Q.acutissima seedlings.