| description: |
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. Photosynthesis is driven by absorbed photosynthetically active radiation. Present models of radiative transfer in vegetation canopies cannot quantitatively adequately explain the variability of radiation fields (transmitted and reflected) in Estonian forests. As a result, monitoring of forest production and forest conditions by using satellite information has not been very successful. Recent 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 forest mensuration parameters have different reflectance, detailed measurements of canopy structure and of optical and biochemical characteristics of phytoelements are planned. Biochemical components determine the 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 suited for basic radiative transfer measurements. The special equipment installed so far will be complemented by new spectral instrumentation which allows to validate different aspects of radiative transfer models. Additional measurements are planned to study productivity of the alder plantation during the second growth cycle, and to compare the radiative transfer and productivity of natural stands to those in cultivated stands.
|