Sensing at Individual Tree Scale
Leaf reflectance was measured in the field for pairwise comparison to stem water potential, and chlorophyll content (Fig. 2). The spectrometer optical cable was held level for pairwise reflectance above and below canopy for these transmittance measurements.
The Backpack ASD Field Pro spectrometer (Fig. 3) was used to make 25 measurements to cover the square between four trees at each sample point. The same protocol was followed for infrared thermometer measurements taken above the canopy (Fig. 4).
Fig. 3. Backpack ASD field pro spectrometer below canopy
Fig. 4. Backpack ASD field pro spectometer
An example of two tree crown shapes measured with LiDAR imagery is provided in Fig. 5. Almond varieties are 'Monterey' on left and 'Non-pareil' on right. This hyperspectral and LiDAR imagery, calibrated with ground data, shows promise in estimating leaf chlorophyll, leaf area, and tree crown shape and size (Fig. 5.) These data will be used in the radiative transfer modeling (PROSPECT-SAIL).