Temporal dynamics of spectral bioindicators evidence biological and ecological differences among functional types in a cork oak open woodland

The application of spectral vegetation indices for the purpose of vegetation monitoring and modeling increased largely in recent years. Nonetheless, the interpretation of biophysical properties of vegetation through their spectral signature is still a challenging task. This is particularly true in M...

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Bibliographic Details
Published in:International journal of biometeorology 2016-06, Vol.60 (6), p.813-825
Main Authors: Cerasoli, Sofia, Costa e Silva, Filipe, Silva, João M. N.
Format: Article
Language:English
Subjects:
Animal Physiology
Biological and Medical Physics
Biophysics
Chlorophyll - metabolism
Cistus
Earth and Environmental Science
Ecology
Ecosystem
Environment
Environmental Health
Fluorescence
Forests
Measurement
Meteorology
Original Paper
Photosynthesis
Plant Leaves - metabolism
Plant Physiology
Portugal
Quercus - metabolism
Radiometry
Rain
Sunlight
Temperature
Ulex
Vegetation
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Summary:The application of spectral vegetation indices for the purpose of vegetation monitoring and modeling increased largely in recent years. Nonetheless, the interpretation of biophysical properties of vegetation through their spectral signature is still a challenging task. This is particularly true in Mediterranean oak forest characterized by a high spatial and temporal heterogeneity. In this study, the temporal dynamics of vegetation indices expected to be related with green biomass and photosynthetic efficiency were compared for the canopy of trees, the herbaceous layer, and two shrub species: cistus (Cistus salviifolius) and ulex (Ulex airensis). coexisting in a cork oak woodland. All indices were calculated from in situ measurements with a FieldSpec3 spectroradiometer (ASD Inc., Boulder, USA). Large differences emerged in the temporal trends and in the correlation between climate and vegetation indices. The relationship between spectral indices and temperature, radiation, and vapor pressure deficit for cork oak was opposite to that observed for the herbaceous layer and cistus. No correlation was observed between rainfall and vegetation indices in cork oak and ulex, but in the herbaceous layer and in the cistus, significant correlations were found. The analysis of spectral vegetation indices with fraction of absorbed PAR (fPAR) and quantum yield of chlorophyll fluorescence (ΔF/Fm′) evidenced strongest relationships with the indices Normalized Difference Water Index (NDWI) and Photochemical Reflectance Index (PRI)₅₁₂, respectively. Our results, while confirms the ability of spectral vegetation indices to represent temporal dynamics of biophysical properties of vegetation, evidence the importance to consider ecosystem composition for a correct ecological interpretation of results when the spatial resolution of observations includes different plant functional types.
ISSN:0020-7128
1432-1254
DOI:10.1007/s00484-015-1075-x