Leaf traits and canopy structure together explain canopy functional diversity: an airborne remote sensing approach

Area of Science:

• Ecology
• Remote Sensing
• Forest Science

Background:

• Plant functional traits significantly influence ecosystem carbon assimilation.
• Forest canopies exhibit complex 3D heterogeneity in traits like foliar nitrogen.
• Traditional hyperspectral and lidar data often lack simultaneous collection, limiting 3D structure-function analysis.

Purpose of the Study:

• To investigate the impact of forest structure on the 3D spatial patterns of plant functional traits.
• To assess how abiotic gradients and management influence canopy nitrogen distribution.
• To fuse hyperspectral and lidar data for a comprehensive understanding of forest ecosystems.

Main Methods:

• Utilized National Ecological Observatory Network's Airborne Observation Platform (NEON AOP) data, combining hyperspectral and lidar measurements.
• Integrated field-collected foliar trait data with remote sensing data.
• Analyzed spatial patterns of top-of-canopy and total canopy nitrogen (N) in a mixed forest landscape.

Main Results:

• Total canopy nitrogen showed dampened variation, presenting relatively homogeneous spatial patterns across the landscape.
• Top-of-canopy nitrogen exhibited significant spatial heterogeneity influenced by abiotic factors and management.
• Leaf functional diversity and canopy structural diversity displayed distinct patterns correlated with plant functional type distribution.

Conclusions:

• Forest structure plays a crucial role in modulating the spatial distribution of plant functional traits, particularly nitrogen.
• Simultaneous hyperspectral and lidar data acquisition is vital for understanding 3D forest structure-function relationships.
• Findings highlight the complex interplay between forest structure, plant traits, and ecosystem function.