Effect Of Forest Tending On Stand Structure And Carbon And Nitrogen Distribution In A Secondary Oak Forest

Secondary oak forest is the main forest type in Henan mountain area.The study on the management and development of secondary oak forest has important theoretical and practical value for the sustainable forest management and ecological construction in Henan mountain area.Forest tending is an important means to optimize the stand structure,adjust the competitive relationship between forest and promote the development of forest stands,which is an important way to achieve sustainable forest management in China at present.The oak natural secondary forest in the south,west and north of Henan mountainous area as the research object,based on near theory natural management of the goal tree was applied to the forest tending of secondary oak forest with similar growth and environmental conditions,and according to the density of the stands before and after the establishment of weak degree(21%),moderate(35%),severe(54%)and control(not tending)the treatment of the intensity.In different tending intensity set up a number of sample plots carried out tree survey,ecology survey and soil science survey.To study the effects of different tending intensity on Henan mountain oak natural secondary forest diameter and tree height distribution,fine root surface layer structure characteristics,different forest layer biomass and carbon nitrogen distribution characteristics,and soil carbon nitrogen distribution,provide theoretical supportas for oak natural secondary forest sustainable management in mountainous areas of Henan province.The main conclusions are as follows:1、 From the secondary oak forest diameter and height distribution variation before and after forest tending can be seen,forest tending promoted the formation of reasonable stand diameter and height distribution,stand diameter and tree height structure were optimized.K-S and A-D analysis of the different thinning intensity of secondary oak forest stand diameter distribution and height distribution were showed,the diameter of the stand was fitted by beta distribution and lognormal distribution and the height of forest trees is best fitted by beta distribution and Weibull distribution.2、 Weak,mid and severe forest tending were beneficial to the natural regeneration of secondary oak forest,and promoted the rapid increase of regeneration density,regeneration densities of weak,mid and severe forest tending were 6187n·hm-2,4512n·hm-2,4925n·hm-2,and the density of weak tending seedlings was the largest.Forest tending promoted the uniformity of seedling distribution and species diversity,the frequency of weak,moderate and severe tending were 77%,100%,111% and 128%,the number of seedlings species increased from 3 in the control to 7in the severe tending.The diversity of Shannon calculated from the effective diversity method proposed by Lou Jost was increased from 1.95 of the control to 5.64 of the severe tending.3、 The PCo A coordinate analysis of the secondary oak forest fine roots in different tending intensity were showed,there was a certain degree of difference in root structure among different tending intensity,fine root dynamics was strongly expressed in 0~10cm,and the variation was small in the 10~20cm layer,the effect of forest tending on fine root morphological structure has obvious vertical distribution characteristics in soil layers,and there were significant differences in the morphological parameters of fine roots in 0~20cm soil layers(P < 0.05).With increasing thinning intensity,was conducive to the surface layer of fine root growth,promote the fine root biomass and root length increased,the rate of root length increased faster than the rate biomass accumulation.4、 According to the survey sample analysis of wood and biomass data to establish the estimation model of the biomass of trees,in different thinning intensity of secondary oak forest tree layer components(stem,bark,branches,Ye Hegen)analysis of the biomass of tree layer showed that the same component biomass among different tending intensity the order were: severe >mid> weak > control.5、 The analysis of biomass,carbon and nitrogen storage of the secondary oak forest tree layer,the understory vegetation and litter layer were showed,weak,mid and severe tending of the biomass,carbon and nitrogen storage in the different vegetation layers of the order were: tree layer > litter layer > understory vegetation layer,and the sereve tending was most beneficial to improve the carbon and nitrogen storage in different organs of the secondary oak forest.Mid and severe tending was beneficial to improve the secondary oak forest understory vegetation layer carbon,nitrogen storage and soil carbon storage,while the carbon and nitrogen storage in litter layer decreased with the increase of tending intensity.