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Open Access item Natural and stress-induced effects on leaf spectral reflectance in Ontario species
|Authors:||Mohammed, G. H.|
Noland, T. L.
Irving, P. H.
Sampson, P. H.
Zarco-Tejada, Pablo J.
Miller, J. R.
|Keywords:||Effect of stress, Spectral reflectance, Measurement|
|Publisher:||Ontario Ministry of Natural Resources|
|Citation:||Forest research report, no. 156|
|Abstract:||This study explores some of the biological factors influencing leaf-based spectral reflectance,
and endeavours to answer the questions: (1) Can Ontario plant species be satisfactorily
distinguished by their leaf spectra? (2) Can spectral properties be used to identify physiological
strain in plants before visual symptoms appear? and (3) How strongly do factors other than
species and stress affect spectral properties? Forty-four species were examined for species
effects. Some general patterns were revealed, including: low reflectance in the near infrared
region for conifers compared to broadleaved species; higher reflectance in the blue wavebands
for species with blue hues in their foliage; and more rapid decay of the green spectral peak in
deciduous tree and shrub species. However, the influence of species was easily superceded by
other factors, such as leaf age, leaf side, and stress status. The effects of stresses such as
senescence and herbicide on leaf reflectance were evident prior to the appearance of visual
symptoms such as chlorosis, browning, and reduced growth. The application of spectral indices
was a useful means to quantify previsual changes in spectral reflectance. The red edge inflection
point was well correlated with chlorophyll content, confirming previous studies. Pooling a
range of coniferous species and stock types, the Photochemical Reflectance Index (PRI) was a
promising early indicator of strain which may have broad application; within species, additional
indices were useful. Normalized difference vegetation indices (NDVI) had limited correlation to
pigments and other physiological indicators of stress status. Altogether, 11 indices reported in
the literature were tested. These findings suggest that leaf reflectance may be an effective early
indicator of physiological strain, and underpin our efforts to develop monitoring tools at
remote scales to aid sustainable forest management.|
|Appears in Collections:||(IAS) Libros y partes de libros|
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