基于无人机遥感的南岭山地树冠与树干性状关联研究

以南岭山地不同海拔高度的冠层树种为研究对象，通过无人机遥感手段获取冠幅、冠周长和冠面积（CA）等树冠性状，探讨其与基径（BD）、胸径（DBH）、2米径（D2）和4米径（D4）等树干性状间的关联性，并构建了冠面积与树干性状间的回归方程。结果表明：南岭山地树冠性状与树干性状的典型变量显著相关（R=0.89，P<0.01），并且这种相关性随海拔的升高（600 m到1 600 m）总体呈“M”型变化。其中，冠面积与树干性状间的相关性最高，可作为单一自变量反演树干性状，具体方程为：DBH=0.35CA+14.88（R²=0.67），BD=0.41CA+17.89（R²=0.82），D2=0.33CA+14.14（R²=0.84），D4=0.35CA+11.3（R²=0.86）。文章构建的冠面积与树干性状间的回归方程，可作为南岭山地森林生物量遥感反演的基础，也可用于指导南岭森林生态系统的长期监测。

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

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: