The Relationship between Crown and Trunk Traits of Trees in the Nanling Mountains

Abstract

There is a close quantitative relationship between crown traits and trunk traits and the relationship can be used to invert each other, calculate forest biomass and stock volume, and guide afforestation practice. The correlation between tree crown and trunk traits is quite different in different regions, and relevant research on the Nanling mountains is lacking. To find out the correlation between canopy and trunk traits and its relationship with altitude in the Nanling mountains, as well as to explore the feasibility of retrieving trunk traits and calculate forest biomass and stock in these mountains, forests with broad-leaf trees distributed at different altitudes (600, 800, 1000, 1400, and 1600 m) in these Mountains were selected as the research objects for this study. Unmanned aerial vehicle remote sensing was used to obtain canopy traits such as crown width, crown circumference, and crown area (CA) of canopy tree species. The correlation between basal diameter (BD) and tree trunk traits-Diameter at breast height (DBH), diameter at 2 m height (D2), and diameter at 4 m height (D4)-were investigated and regression equations were established. A high correlation was observed between crown traits and trunk traits in the Nanling mountains, and the correlation was statistically significant to invert trunk traits from crown traits. The correlation between tree crown traits and trunk traits significantly differed with elevation in these mountains, revealing an "M" shaped change with elevation. Among the crown traits selected in this study, the correlation between crown area and trunk traits was the highest, implying that it could be used solely for inversion of trunk traits. The specific equations were as follows:

Keywords

• unmanned aerial vehicle remote sensing
• crown circumference
• vertical projection area
• biomass inversion
• altitude, nanling mountains