The Growth Characteristics Of Larix Principis-rupprechtii Plantaion In The Southern Part Of Liupan Mountains And The Impact Factors

This study was performed for Larix principis-rupprechtii artifical plantations in the the southern side of Liupan Mountain in Ningxia.The author used a lot of study methods,for example,stem analysis of sample trees,comparing annual increment and average increment of individual growth factors and giving appropriate growth curves,and then analyzed the growth process of Larix principis-rupprechtii artifical plantations.The optimal stand density of Larixprincipis-rupprechtii in this area and the meteorological factors that affect trees growth were discussed on the basis of the research result to provide the theory basis for managing.And Based on the data of 12 standard sample plots of Larix principis-rupprechtii plantations,find the regularities of distribution by analysis of diameter distribution.And Using distribution function to fit the transformation regularities to set up parameter regression model to predict the future diameter distribution and discuss the stand structure regularities of Larix principis-rupprechtii artifical plantations.The results are followed:The current annual increment maximum of the tree height and the breastdiameter arrived at the stand age of 21 years;But the current annual increment of tree height was intersected with the mean annual increment in about 20a,the current annual increment and mean annual increment of the breastdiameter intersected in 17a;The current annual increment and the mean annual increment of the timber volume was not able to intersect in 21a,that means that the Larix principis-rupprechtii' growth process could not reach its quantitative.There was no significant growth difference among different densities(1 200,1 500 and 2 000 stems·hm^-2) when the stand age was less than 10 years.But there was significant growth difference in timber volume of individual trees and of stand volume when the stand age was more than 10 years.The tree growth in the low-density stand(1 200 stems·hm^-2) was apparently better than that in the medium(1 500 stems·hm^-2) and high-density stands(2 000 stems·hm^-2).However,there was no significant height growth difference among the three densities.The reasonable remaining density of Larix principis-rupprechtii plantations was suggested to be 1 200 stems·hm^-2 at the stand age of 21 years.Using the meteorological weather data from Weather Bureau of Jingyuan,the effection between eight meteorological factors and growth of Larix principis-rupprechtii was discussed by the partial correlation analysis.Combining with the principle component analysis,the results indicated that precipitation is the most important one among all of factors that affect trees growth.The diameter of plantations is presented single apex curve either left or right.In the stands of same age,the density is more higher,the diameter distribution is more prone to left.And most of the kurtosis are positive value.The regression faction b = b₀ + b₁×(?)+ b₂×Nå’Œc = c₀+c₁×(?) + c₂×N which used Weibull parameters to get and tree survey factors could be calculated the parameters,thereby to predict the future diameter class distribution.The diameter class distribution models developed in the study reflected the rules of diameter distribution for Larix principis-rupprechtii plantation impersonally,also could be helpful to stand structure and growth rules research,therefore this research has the theoretic foundation and practical value.