Analysis of the factors affecting trunk density and wood density of three native tree species in Guangdong Province of southern China

Objective The effects of different factors on trunk density and wood density were analyzed to provide data support for tree breeding and carbon sequestration measurement.

Method Based on the measured data of trunk density and wood density of Cinnamomum camphora, Schima superba and Liquidambar formosana, which are three native tree species in Guangdong Province of southern China, using multifactor analysis of variance with covariate and no interaction to screen out factors affecting trunk density and wood density from 30 factors (11 qualitative factors and 19 quantitative factors) of five categories, and then the boosted regression trees(BRT) was used to analyze the influence of different factors on trunk density and wood density of three species.

Result (1) Vegetation type, height under branch, DBH, vegetation coverage and the crown width from east to west are the main factors affecting trunk density of Cinnamomum camphora. City and vegetation type are the main factors affecting trunk density of Schima superba. Slope aspect, altitude and average height are the main factors affecting trunk density of Liquidambar formosana. The main factors affecting trunk density of three tree species are different and there was no common main factors in them. (2) The main factors affecting wood density of Cinnamomum camphora are height under branch, vegetation type, altitude, vegetation coverage, average height, shrub coverage, age, DBH, forest category and soil thickness. The main factors affecting wood density of Schima superba are age, herb coverage, height under branch, average DBH, soil thickness and vegetation type. The main factors affecting wood density of Liquidambar formosana are slope aspect, altitude, average height, height under branch. The height under the branch is the common main influencing factor, affecting wood density of the three tree species, and the relative influence upon three tree species was similar, all of which was about 10%. (3) Stand factor and single tree factor are the dominant factors affecting trunk density and wood density of Cinnamomum camphora, and their total relative influence rates were 87.04% and 76.92%, respectively. Stand factor, single tree factor and regional factor are the dominant factors affecting trunk density of Schima superba, and the total relative influence rate was 79.96%. The dominant factors affecting wood density of Schima superba are stand factor, single tree factor and soil factor, and the total relative influence rate was 83.04%. Terrain factor, stand factors and single tree factor are the main factors affecting trunk density and wood density of Liquidambar formosana, and their total relative influence rates were 83.98% and 92.70%, respectively.

Conclusion This paper analyzes different factors by multifactor analysis of variance and BRT, and it is concluded that stand factor and single tree factor are the dominant factors affecting trunk density and wood density of Cinnamomum camphora, Schima superba and Liquidambar formosana.