Research On Natural Quercus Mongolica Forest In Changbai Mountains Classification Of Different Site Types Of Stand Growth Differences

In this paper,490 natural Quercus mongolica forest sample plots in Changbai Mountains were statistically analyzed.After site type division,site model selection and growth model fitting,the average growth,annual growth and extreme growth 3indexes of different site types were calculated,so as to obtain the growth differences of different site types of Quercus mongolica forest stands and draw the distribution map of natural Quercus mongolica forest types in Changbai Mountains.The distribution map can accurately grasp whether the site conditions of natural Quercus mongolica forests in counties and cities of Changbai Mountains are suitable for the growth of natural Quercus mongolica forests,and provide scientific basis for the production and management of natural Quercus mongolica forests.The main results are as follows:(1)The natural Quercus mongolica forest sample plots were finally divided into four site types by principal component analysis and cluster analysis.The comprehensive scores of principal components of site Types I,II,III and IV were0.1352～0.2696,0.2696～0.4035,0.4035～0.5386 and 0.5386～0.686 respectively.Among them,Type I is mostly distributed in shady slope,middle slope,steep slope and thin soil,Type II is mostly distributed in semi-shady slope,uphill,slope and thin soil,Type III is mostly distributed in sunny slope and semi-sunny slope,uphill,slope and middle soil,and Type IV is mostly distributed in sunny slope,uphill,gentle slope and middle soil.The investigated sample plots are mostly distributed in the site conditions of low mountains and thin soil humus.(2)By comparing 9 common site models,it is concluded that the 3 test values of mean relative error(EE),mean relative error absolute value(RMA)and mean square of variance(MSE)of Logistic model are the smallest,which are the closest to 0,and the stand growth curve is the closest to S-type,which is the most suitable for fitting the stand growth model of natural Quercus mongolica forest.(3)After simplifying the full model of 3 heterogeneous parameters of natural Quercus mongolica stands with different site types,a 2 heterogeneous parameter model is finally obtained.There are significant differences in parameter A and parameter C among different site types,but there is no significant difference in parameter B.By comparing the parameters A and C of the growth model of different site types,it can be known that the parameters A of Type I and Type III,Type I and Type IV,Type II and Type III are significantly different,which indicates that the maximum growth of stand per hectare of these three site types is quite different.Comparing the site types of Type I and Type III,Type I and Type IV,the parameter C is significantly different,indicating that the maximum growth rate of the two site types is quite different.(4)By comparing the average growth volume,annual growth volume and extreme growth volume of natural Quercus mongolica stands with different site types,it can be known that the age when site types I,II,III and IV reach quantitative maturity is 59 years,58 years,67 years and 63 years respectively,and the average growth volume is 2.2118 m~3/hm~2,2.3562 m~3/hm~2 and 2.4638 m~3/hm~2respectively.The annual growth of site types I,II,III and IV reached the maximum in 44 years,43years,50 years and 46 years respectively,and the cumulative annual growth was2.8070 m~3/hm~2,2.9905 m~3/hm~2,3.1265 m~3/hm~2 and 2.9972 m~3/hm~2 respectively.The accumulation growth extremes of site types I,II,III and IV are 179.10 m~3/hm~2,188.70 m~3/hm~2,226.20 m~3/hm~2 and 202.90 m~3/hm~2 respectively.When the average accumulation growth,annual accumulation growth and accumulation growth extremes of site Type III reach the maximum,the hectare accumulation is the largest,which is most suitable for the growth of natural Quercus mongolica forest in Changbai Mountains.(5)According to the data of‘one map’of forest resources management in Changbai Mountains in 2019,the site types of natural Quercus mongolica forest subcompartments in Changbai Mountains were typeified.The proportions of subcompartments with site types of Type I,Type II,Type III and Type IV were19.29%,33.92%,39.74%and 7.04%respectively.