Effects of background variations on vegetation indices for mangrove forest in Taklong Island, Guimaras Province

摘要

This study investigated the effects of various background conditions typically found in mangrove communities on the relationships on various spectral vegetation indices and leaf area index. ASTER image was used to identify/classify mangrove areas within the study area. Mangrove canopy spectral reflectance and leaf area index (LAI) were measured in the field using a spectrometer and Photosynthetically Active Radiation (PAR) sensor. These data were then used to calculate Spectral Vegetation Indices such as NDVI, SAVI_2, and OSAVI. The relationships between several spectral vegetation indices measured from the field and derived from ASTER image and field LAI have been assessed particularly the effects of background variation typically found beneath mangrove canopies. As expected, soil influences are prevailing in partially vegetated canopies, they are more significant in LAI below 1.5. Based on the correlation coefficient, the vegetation indices which consider soil parameter normalized the soil-background effects such as SAVI2, OSAVI, with corresponding regression coefficient of 0.81, 0.74, respectively. Based on the result of 3D plot of SMA over various types of vegetation indices, SAVI_2 turned out to be sensitive to background or substrate variations in almost all types of substrates.