Scattering and absorption of radiation energy in natural
and cultivated vegetation canopies
Abstract
Visible and near and middle infrared (400-2500 nm) solar radiation
reflected from vegetation canopies is the source of information on the
structure and conditions of vegetation. Absorbed photosynthetically
active radiation drives photosynthesis. Present models of radiative
transfer in vegetation canopies cannot explain the variability of
radiation fields (transmitted and reflected) in Estonian forests. As a
result, monitoring of forest production and forest conditions using
satellite information is still not very successful. Resent theoretical
studies revealed the role of crown shape in forming reflected
intensities. In order to find reasons why stands of similar site and
of similar mensuration parameters have different reflectance, detail
measurements of canopy structure and of optical and biochemical
characteristics of phytoelements are planned. Biochemical components
determine optical properties of phytoelements in the spectral region
1-2.5 µm, obviously in the region 2.5-8 µm as well. Spectral
measurements in this region (1-8 µm) will be performed in order to
relate optical properties of phytoelements to their composition. The
plantation of energy forest at Tõravere is well studied and special
equipment is installed which allows to validate radiative transfer
models. Additional measurements are planned to study productivity of
the alder plantation during the second growth cycle, and to compare
radiative transfer and productivity of natural stands to those in
cultivated stands.
5 August 2004