Instruments and methods of measurement laser method for vegetation monitoring

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INSTRUMENTS AND METHODS
OF MEASUREMENT
LASER METHOD FOR VEGETATION MONITORING
М.L. Belov, O.A. Bullo , Yu.V. Fedotov , V.А. Gorodnichev
Bauman Moscow State Technical University, Moscow, Russian Federation
e-mail: ;
The paper considers a laser fluorescence method for vegetation monitoring. It
presents the results of an experimental study of plants’ laser-induced fluorescence
spectra under various stress conditions caused by the presence of soil pollutants,
excess water or mechanical damages. At the fluorescence excitation wavelength
of 532 nm, the impact of different stress factors proves to manifest itself in both
increasing the laser-induced fluorescence intensity and changing the form of the
fluorescence spectrum, according to stress types and various vegetation types.
Fluorescence intensities ratio at two wavelengths of 680 and 740 nm can be
regarded as an identifying factor characterizing the form change of the laser-induced
fluorescence spectrum. Measurement of both the intensity and spectrum form of
plants’ laser-induced fluorescence can be the basis of the laser method for detecting
plants’ stress conditions.
Keywords: laser method, fluorescence, vegetation, detection of stress conditions.
Methods based on the analysis of the laser-induced fluorescence spectra
are widely used in science and technology. The development of high-power
pulsed lasers has made it possible to use the methods of fluorescence
analysis in remote sensing. The vegetation monitoring can be considered
as one of the promising field of laser fluorescence analysis application
[1–16].
Stress conditions in plants can be caused by many reasons such as
lack or excess of soil dampness; mechanical damages; diseases; low or
high temperatures; lack of nutrients; lack of light; soil salinization; soil
contamination by heavy metals or petroleum products; excessive soil
acidity; the use of pesticides, herbicides, insecticides, etc.
Such stress conditions are difficult to identify at the early stages judging
by the appearance of plants. However, the fluorescence analysis can detect
plants’ potentially stress conditions based on the spectrum distortion of
laser-induced fluorescence.
The operating principle of the laser fluorometer used for plants’
condition monitoring is based on vegetation laser irradiation in the forms
of either ultraviolet or visible light (for fluorescence excitation), as well as
on the registration and analysis of fluorescent radiation.
The most important informative fluorescence indicator is a form of
vegetation fluorescence spectra.
ISSN 0236-3933. HERALD of the BMSTU. Series “Instrument Engineering”. 2015. No. 2 71