The Adjustment Technique And Target Structure Of Pine-oak Mixed Forest In Qinling Mountains

24plots of pine-oak mixed forest were taken in Qinling mountains, the speciescomposition, diameter class structure, height class structure, regeneration characteristics ofthe constructive species, species diversity and spatial structure was studied. Target structuresystem which conforms to the pine-oak mixed forest community was put forward referencingto previous research results, furthermore, the health management technology system based ontarget structure adjustment was presented combine the unreasonable structure of existingstands and the measures of close to nature management and multi-function forestmanagement, in order to improve the health level of forest ecosystem in Qinling mountainsand provide scientific foundation and theoretical basis of health management and sustainabledevelopment of forest ecosystem. The main results showed that:(1) The diameter class distribution of the community presents the inverted J, which isclose to the ideal structure. The constructive species Pinus Tabuliformis and Pinus armandiihave fewer plants in smaller diameter class, which is declining population. Diameter classdistribution of Quercus aliena var.accuteserrata closes to the inverted J, the construction isrelatively stable. The tree is more in middle class and less in small class and large class.(2) The regeneration of Pinus armandii and Quercus aliena var.accuteserrata arerelatively preferable, but Pinus. Tabuliformis is relatively poor. Regeneration of Quercusaliena var.accuteserrata (876No·/hm2) is better than Pinus. Tabuliformis (167No·/hm2) andPinus armandii (209No·/hm2) in Huo Ditang, but in Foping, the regeneration of Quercusaliena var.accuteserrata (110No·/hm2) is poor, but the regeneration of Pinus. Tabuliformis(618No·/hm2) and Pinus armandii (1754No·/hm2) are relatively preferable. Forest gap ispossibly beneficial for their regeneration.(3) Patrick index shows that: species in shrub layer are most (8.867), tree layer second(7.933), herb layer least (7.133). Simpson index, Shannon-Wiener index and Pielou indexshow that species diversity in shrub layer is higher than tree layer and herb layer, speciesdiversity in tree layer is lowest. Species diversity combines richness and evenness.(4) The mean value of uniform angle index is0.527, which tend to light aggregateddistribution. The mean value of diameter neighborhood comparison is0.494, dominant treesare rich. Average mingling degree is0.611, which is the moderate intensity mixed. The uniform angle index is nearly symmetrical on both sides of0.5, which is close to normaldistribution, and ratio of value0and1is low. The distribution frequency of the five values ofthe neighborhood comparison has small differences. The distribution frequency of minglingdegree gradually increasing from0to1, which indicates that the ratio of strength mixed andhigh-strength mixed is higher than weak mixed and extremely weak mixed.The ratio of the neighborhood comparison0and0.25of Pinus. Tabuliformis is higherthan0.75and1, therefore, the dominance of Pinus. Tabuliformis is obvious. The dominanceof Pinus armandii is poor, and Quercus aliena var.accuteserrata is the most dominant. Thedistribution of mingling degree of Pinus. Tabuliformis is uniform, but the mixed degree ofPinus armandii and Quercus aliena var.accuteserrata are higher.(5) Target structure system of pine-oak mixed forest was put forward on the basis of theexisting problems of forest structure and referenced healthy management and multifunctionforest management theory:①Species composition：4pine3oak3associated species or5pine3oak2associated species.②Viability: canopy density is0.6to0.8, and the coverage ofshrub and herb is greater than60%.③Spatial distribution: random distribution, intensitivelymixed and dominant species are prominent.④Distribution of diameter class and age:inverted J; small DBH(5-20cm): middle DBH(20-35cm): large DBH(≥35cm)=2:3:5; q valueis1.2-1.7.⑤Regeneration: regeneration species are mainly pine and oak, and the of Pinus.Tabuliformis.Management technique:①Adjust species compositon: cut the oppressed trees, keep thegood trunk, control the species proption.②Adjust stand structure: select cutting trees by thediameter class, cut down the overlord trees, using individual selective cut, make the diameterclass structure is inverted J type. Adjusting the aggregated distribution and even-distributedunit to make the distribution of uniform angle index more uniform. Cut down the species ofzero mixed and weak mixed.③Promote the regeneration: create forest gap and decrease thethickness of the litter to promote the regeneration of Pinus Tabuliformis.