Estimating Needle and Shoot Inclination Angle Distributions and Projection Functions in Five <i>Larix principis-rupprechtii</i> Plots via Leveled Digital Camera Photography

• Main Authors: Jie Zou, Peihong Zhong, Wei Hou, Yong Zuo, Peng Leng
• Format: Article
• Language: English
• Published: MDPI AG 2021-12-01
• Series: Forests
• Subjects: needle inclination angle distribution; shoot inclination angle distribution; leveled digital photography; G function; coniferous forest; Larix
• Online Access: https://www.mdpi.com/1999-4907/12/1/30

The leaf inclination distribution function is a key determinant that influences radiation penetration through forest canopies. In this study, the needle and shoot inclination angle distributions of five contrasting <i>Larix principis-rupprechtii</i> plots were obtained via the frequently used leveled digital camera photography method. We also developed a quasi-automatic method to derive the needle inclination angle measurements based on photographs obtained using the leveled digital camera photography method and further verified these using manual measurements. Then, the variations of shoot and needle inclination angle distribution measurements due to height levels, plots, and observation years were investigated. The results showed that the developed quasi-automatic method is effective in deriving needle inclination angle distribution measurements. The shoot and needle inclination angle distributions at the whole-canopy scale tended to be planophile and exhibited minor variations with plots and observation years. The small variations in the needle inclination angle distributions with height level in the five plots might be caused by contrasting light conditions at different height levels. The whole-canopy and height level needle projection functions also tended to be planophile, and minor needle projection function variations with plots and observation years were observed. We attempted to derive the shoot projection functions of the five plots by using a simple and applicable method and further evaluated the performance of the new method.