Effectsof Tending Thinningon Growthand Carbon Fixationofquercusalienavar.acuteserrata Forestonthe South Slopeof Qinling Mountains

Forest tending is an important measure to promote the growth and qualityof stand,and the study about the effect of different thinning intensity on the growth of stand and the ability of carbon sequestration,which can clarify the relationship between tending thinning and the growth of stand and the ability of carbon sequestration and provide theoretical basis to scientific management of the forest.In this study,the research site was located in the sand ditch forest of Ningdong Forestry Bureau in Shaanxi Province and the Quercus aliena var.acuteserrata forest was the object of study.The sample-plots were set according to 0%,5%,10%,15%,20% and 25 % thinning intensity.The results of study showed that:(1)The growth of basal area,tree height,stored volume,biomass and the carbon stock was the highest with the thinning intensity at 5%,which were(7.22 ± 0.01)m2,(0.77 ±0.03)m,(48.49±0.01)m3,(48.28±0.00)t·hm-2 and(23.47±0.01)t·hm-2,respectively.The growth of basal area was the smallest with the thinning intensity at15%(5.44± 0.97)m2.The growth of tree height was the smallest with the thinning intensity at25%(0.45±0.07)m2,and the stored volume of CK,the biomass and the carbon stock were the smallest of(39.28 ± 0.96)m3,(39.12±0.95)t·hm-2 and(19.01±0.47)t·hm-2,respectively;(2)The growth rate of basal area,stored volume,biomass and carbon stock with the thinning intensity at 5% were higher than other thinning intensities within the five years after thinning,respectively,(32.38±1.61)%,(39.16±2.13)%,(25.57±1.45)% and(25.57±1.45)%;(3)The trends of the basal area,stored volume,biomassand the carbon stock were increased with time,and the growth trend was the most obvious with the thinning intensity at 5%.The annual growth rate of tree height was decreasing with time;(4)It could promote the increase of the basal area and stored volume of small diameter and medium diameter Quercus with thinning intensity;(5)Small diameter trees contributed significantly to the growth of Quercus aliena var.acuteserrata forest after tending thinning,and the contribution was decreased with the increase of the diameter;(6)It was the most significant effect on the growth and the ability of carbon sequestration of Quercus aliena var.acuteserrata forest with the thinning intensity at 5%.