Is the spherical leaf inclination angle distribution a valid assumption for temperate and boreal tree and shrub species?
Abstract
Directional distribution of leaves is one primary parameter for determining the radiation transmission through the canopy. When inverting canopy transmittance measurements for estimating the leaf area index or foliage clumping, incorrect assumptions on leaf angles may lead to considerable errors. Often spherical distribution of leaf normals is assumed, i.e. leaf normals are assumed to have no preferred direction in situations where no measurement data are available. The goal of this study is to examine if a spherical leaf angle distribution and the resulting isotropic G-function (G≡0.5) is indeed a valid assumption for temperate and boreal tree and shrub species. Leaf angle distributions were measured for over 80 deciduous broadleaf species commonly found in temperate and boreal ecoclimatic regions. The leaf inclination angles were obtained by sampling the complete vertical extent of trees and shrubs using a recently introduced technique based on digital photography. It is found a spherical leaf angle distribution is not a valid assumption for both tree and shrub species in temperate and boreal ecoclimatic regions. Given the influence of leaf angle distribution on inverting clumping and LAI estimates from canopy transmittance measurements, it is recommended to use planophile or plagiophile leaf angle distribution as more appropriate for modeling radiation transmission in temperate and boreal ecoclimatic regions when no actual leaf inclination angle measurements are available.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.B41E0368P
- Keywords:
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- 0434 BIOGEOSCIENCES / Data sets;
- 0439 BIOGEOSCIENCES / Ecosystems;
- structure and dynamics;
- 0452 BIOGEOSCIENCES / Instruments and techniques;
- 0476 BIOGEOSCIENCES / Plant ecology