Difference Analysis Of Stand Characteristics Of Larix Principis Rupprechtii Plantation Under Different Site Conditions

In order to explore the differences in the basic characteristics of Larix principis-rupprechtii plantation under different site conditions in Weichang County of Chengde,the Larix principis-rupprechtii plantation in Beigou Forest Farm was studied by using the second-class survey data,combined with standard survey,trunk analysis and other methods.The difference of stand structure,tree growth law and understory biodiversity under different site conditions(altitude,slope direction,slope position)were analyzed using statistical analysis software.The main findings were as follows:(1)The best distribution among the four fitting distributions of normal distribution,Weibull distribution,lognormal distribution,and logistic for the DBH structure of Larix principis-rupprechtii stands under different site conditions was normal distribution,but its skewness,steepness and peak value were different.The skewness values of the normal distribution curve of diameter at breast height of forest stands at high altitude,middle altitude and low altitude were:-0.19,-0.03,-0.06;their kurtosis values were:-0.70,-0.66,-0.75;its peaks appeared in 20 cm,22 cm,and 22 cm diameter steps respectively.The skewness values of the normal distribution curves of diameter at breast height of the shade and sunny slope forests were:-0.12,-0.10;the kurtosis values were:-0.57,-0.78;the peak values appeared at 22 cm and 20 cm diameter respectively Order.The skewness values of the normal distribution curve of diameter at breast height of the uphill,middle and downhill stands were:-0.05,-0.09,-0.15;the kurtosis values were:-0.81,-0.78,-0.60,respectively;Its peaks appeared in 18 cm,1 8 cm,and 20 cm diameter steps respectively.(2)Among the four fitting distributions of normal distribution,Weibull distribution,lognormal distribution,and logistic distribution,the best distribution of tree height structure of Larix principis-rupprechtii stands under different site conditions was normal distribution,but its skewness,Kurtosis and peak were different.The skewness values of the normal distribution curve of tree height for high-altitude,middle-altitude,and low-altitude forest stands were:0.26,-0.15,-0.11;the kurtosis values were:-0.40,-0.36,-0.11;its peaks appeared at 16 m,18 m,and 16 m tree levels respectively.The skewness values of the normal distribution curves of tree heights for shade and sunny slope forests were respectively:-0.66,-0.52;their kurtosis values were:-0.45,-0.09,respectively;their peaks appeared at 16 m tree height respectively.The skewness values of the normal distribution curve of tree height for the uphill,middle and downhill stands were:0.02,-0.12,0.02;the kurtosis values were:-0.88,-0.80,-0.59;The peaks appeared at 14 m,16 m,and 18 m tree level respectively.(3)Site conditions had varying degrees of influence on the growth of Larix principis-rupprechtii.The effect of altitude on the DBH,tree height and volume of Larch plantations in North China was as follows:the growth of DBH in low-altitude forest stands is higher than that in middle-and high-altitude stands,although the difference was small.The growth was significantly higher than that of low-altitude and high-altitude forests,and the low-altitude volume growth was relatively higher than that of middle-altitude and high-altitude forests;the slope aspect had an effect on the tree height,DBH and volume of the Larch forest Forests on shady slopes were better than those on sunny slopes;the effect of slope position on DBH,tree height and volume of Larch plantation forests was that the DBH,tree height and volume growth of forest stands on the downhill slope were significantly higher than those on the middle slope and uphill.Slope stands,but the difference between mid-slope and upslope stands was small.(4)The plant richness and diversity of Larix principis-rupprechtii stands under different site conditions were significantly different.The stands of different altitudes,slope directions and slope positions all show that herbaceous plants were more abundant than shrubs and were more evenly distributed.In addition,the Margalef richness index,Simpson diversity index,Shannon-Wiener diversity index,and Pielou evenness index in the shrub layer and herb layer of forest stands with different site conditions follows:low-elevation forest>mid-elevation forest Points>High-altitude forests;Shady slope forests>Sun slope forests;Downslope forests>Middle slope forests>Upslope forests.