Study On Growth Law And Optimal Management Model Of Larix Kaempferi Plantations In Western Of Qinling Mountains

Based on the collected data, the growing process of Larix kaempferi plantation inwestern of Qinling was investigated by using the method of stem analysis. And throughgrowth model we can determine a reasonable harvesting Age. According to differentcultivation objectives we can determine the different thinning intensities. The best managingmode was obtained in order to provide scientific basis for sustainable operation andmanagement of Larix kaempferi plantation in Qinling Mountains. The results showed that(1) Selected five kinds of common growth models to fit the DBH, tree height, volumegrowth of Larix kaempferi plantation in western section of Qinling, from fitting result can beseen Richards curve as growth forecast model of DBH, tree height, volume growth processfitting results are the best for Larix kaempferi plantation in western of Qinling. So we chooseRichards curve as the DBH, tree height, volume growth model of Larix kaempferi plantationin western of Qinling.(2)Both current annual DBH increment and annual height increment reached the maximumvalues in8years, the current annual volume increment reached the maximum values at theage of20years, and the peak value of current annual volume increment appeared at age of28years. Hence, the quantitative maturity of Larix kaempferi plantations is28years. Comparedthe growing process of Larix kaempferi plantations in five siteclass, both current annual DBHincrement and annual height increment of each siteclass reached the maximum values in8years, so both of them should be firstly fostered by thinning at the age of8years. With theincreasing of siteclass, the age of current annual DBH, height and volume increment reachedthe maximum would be put off. Therefore, the quantitative maturity of Larix kaempferiplantations in each siteclass at the ages of26-30years..(3) Analyzed the volume growth process of Larix kaempferi plantations in each siteclass,itshows that the mature ages of Larix kaempferi plantations in each siteclass were26,28,28,29,30years; Technology maturity age was based on the age of DBH reached which is timberspecies required. The technology maturity age of siteclass Ⅳand siteclassⅤat9a and10a forsmall-diametertimbe. The technology maturity age of siteclass Ⅰ,siteclassⅡand siteclassⅢ at 9a,10a and11a for middle-diametertimbe, and The technology maturity age of large-diametertimber is more than40years; The economies mature ages calculated by NPV were18,19,20,22,24years. The economies mature ages calculated by IRR were9,11,11,13,17years.(4)Choosing normal distribution function to describe the diameter distribution of Larixkaempferi and test with chi-square test method. It can be seen from the fitting results that thediameter distribution curve skewed to the right in every siteclass. The peak values are allnegative. It indicated that the diameter distribution curve is relatively flat and the degree ofdispersion of diameter class distribution is large. Most of them concentrated in the middlediameter class of trees. There are also large diameter distribution and few small diameterdistribution.(5)The optimum density table of Larix kaempferi plantation in different siteclasswas draw up. Then we need determine different cutting intensity of different siteclass, andinitial thinning time, Intermediate cutting interval is eight years. According to differentcultivation objectives we can determine the harvesting age. optimizing the managementmodel.