Effects Of Thinning On Structure Of Quercus Wutaishanica Populations And Forest Quality In Huanglong Mountains,Northwest China

In order to study how to optimize the structure of Quercus wutaishanica populations and forest quality,this research focuses on thinning on the natural secondary forest of Q.wutaishanica on Huang Long Mountains and analyzes effect of thinning after 10 years,mainly including the influence of Q.wutaishanica forest trees form quality,population structure,forest stand quality,to provide the basis of optimizing the thinning technology,Q.wutaishanica forest management technology measures and continuous operations.The main results were as follows:1.Oderate tending thinning can improve forest trees form quality.Constructing the Q.wutaishanica form quality evaluation system by using the analytic hierarchy process(AHP),with growth situation(height mean annual increment,DBH mean annual increment,crown diameter ratio,health condition),stem form situation(round degree,tree tapering,stem straightness,bifurcation situation),lateral branch situation(natural ability of self thinning,lateral branch numbe,index of branch coarse,average base diameter of branches)as Q.wutaishanica form quality evaluation index,calculate Q.wutaishanica trees form quality scores of comprehensive evaluation with the heavy thinning(keeping crown density of 0.6),medium thinning(keeping canopy density of 0.7),light thinning(keeping crown density of 0.8)and control plots(crown density of 0.9).The evaluation results show that DBH mean annual increment and tree tapering were with the thinning intensity increases,but increase of tree tapering was not conducive to prove Q.wutaishanica form quality and thinning intensity had no significant influence on them.Thinning intensity had significant influence on other ten indexes,height mean annual increment,health condition and natural ability of self thinning were with the thinning intensity increases,and round degree decreased with the thinning intensity,but it is conducive to prove Q.wutaishanica form quality.Trees form quality score firstly increases and then decreases with the increase of thinning intensity so that medium thinning has the highest score and Q.wutaishanica form quality of medium thinning is thebest.2.Age class,static life table,survivorship curve,height class and crown width class,researching age class,static life table,survivorship curve,height class and crown width class were drew to survey the change rule in different crown density(crown density is 0.6?0.7?0.8and 0.9)under different slope(shady slope and sunny slope).The results showed that Q.wutaishanica saplings respectively made the total individual number 57%?64%?36%?47%in different crown densities(crown density is 0.6?0.7?0.8 and 0.9),age class,static life table and survivorship curve indicate the Q.wutaishanica seedlings in four different crown densities,the Q.wutaishanica seedlings made the maximum proportion,and then the adult trees,saplings made the least proportion.In both the sunny slope and shady slope,crown density of 0.7 is more suitable for Q.wutaishanica to update and grow,which can be used as ideal conditions of tending thinning in Northwest of China.3.Using the analytic hierarchy process to evaluate Q.wutaishanica forest stand quality forest in different thinning intensity(crown density is 0.6?0.7?0.8 and 0.9)under different slope(shady slope and sunny slope).The results showed that comparing with the controls,DBH mean annual increment was with the thinning intensity increases,but thinning intensity had no significant influence on it and thinning intensity had significant influence on other eleven indexes in both the sunny slope and shady slope.In the sunny slope,seedlings and saplings density,number of seedlings and saplings of constructive species/ number of constructive species,frequency situation,shrub coverage and herb coverage were with the thinning intensity increases,but stock volume and litter depth were decreased with the thinning intensity.In the shady slope,Species richness,Height mean annual increment,Shrub coverage and Herb coverage were with the thinning intensity increases,but stock volume was decreased with the thinning intensity.In both the sunny slope and shady slope,with the increase of thinning intensity,Q.wutaishanica forest quality was firstly increases and then decreases,so medium thinning(crown density of 0.7)is the best optimum thinning intensity for it.