The slope effect and correction methods for estimation of canopy gap fraction, leaf area index (LAI), mean leaf angle and clumping index using hemispherical photography, were investigated.
Further, subcanopy model calibration requires significant field effort and knowledge of characteristics (species composition, leaf area index & mean leaf angle for each species), and upscaling to watersheds is a significant source of uncertainty.
Curiously, during autumn the angle of the leaves was progressively reduced (mean leaf angle decreased from 41° in summer to 14° in winter) in parallel with the progressive accumulation of anthocyanins in the lower epidermal layer of cells (Fig. 2B and C).
In these stands crown characteristics varied in terms of LAD (0.27 to 2.62 monthly, monthly k H (0.04 to 1.60), live-crown lengths (2 to 18 m), L A (10 to 390 m2), crown diameters (2.7 to 8.0 m), L A /S A (0.16 to 2.05), mean leaf angles (20° to 70° from horizontal), crown shapes (cones, ellipses, and half-ellipses), and densities ranged from 10 to 5300 trees per ha.
The sensitivity studies were conducted in the visible/near-infrared on the following parameters: the leaf structure (N), the chlorophyll-a and -b content (Cab), the leaf area index (LAI), the mean leaf inclination angle (θl), the hot spot (sl), and the soil brightness (αsoil).
The tiller angle (the angle between the tiller and the horizontal plane) was reduced from 77.5° to 62.8°, 83.8° to 75.0° and 83.4° to 77.2° at the three growth stages, respectively, and the mean leaf inclination angle decreased from 66.2° to 44.3°, 74.9° to 64.2° and 76.0° to 68.3° contrasting Teqing with YIL18.
smg11 influences leaf angle.
Fig. 5 The effect of GNS4 on leaf angle.
Measurements of tree leaf area, leaf angle distributions, leaf area density, and leaf and soil optical properties were performed to parameterize this model.
Leaf characteristics (leaf angle, leaf length, and leaf number), growth form (tiller height and tiller clusters), bud proliferation, and plant fitness differed significantly in situ along the gradient.
Our results are relatively insensitive to canopy architecture, i.e. crown structure, leaf-clumping and the leaf angle distribution.
