Actas de congresos
Modeling forest canopy closure using vegetation index
Date
2013-04-13Registration in:
Anais Online, Foz do Iguaçu : INPE, 2013
Author
Carvalho, Francisco D'Albertas Gomes de
Barbosa, Jomar Magalhães
Bitencourt, Marisa Dantas
Institutions
Abstract
The use of remote sensing to estimate forest structure has been largely tested but few
researches have related such information about canopy closure in tropical forests in steep
slope. This work aims to analyze the potential employ of vegetation index and sunlight
radiation to generate a predictive model of canopy closure in the Ribeira Valley, south of the
São Paulo State – Brazil. The canopy closure data were obtained from Spherical Densiometer
in 52 sample points. The sun radiation (AIF) was obtained using TOPODATA image and
literature equations. Thus, canopy closure and AIF information were related to NDVI, EVI
and LAI, obtained from LANDSAT-TM and ALOS-AVNIR images. The results showed: a)
field canopy closure facing to the North, East and West presented a tendency to have higher
canopy closure then points facing to the south; b) the field canopy closure ranged from 0.58 to
0.97 c) and the annual illumination factor (AIF) ranging from 0.28 to 0.66 ; d) all three
indexes showed lower determination coefficients when compared with image bands alone; e)
two spatial resolution images were tested using 30 m (TM) and 10 m (ALOS); the lower pixel
size did not result in better canopy closure estimation; f) the use of topographic correction on
the TM images did not resulted in better model explanation of canopy closure, comparing it
with models that use AIF; g) the blue ALOS band and TM7 Landsat band models explained,
about 27% and 30% of the variation in observed canopy closure, respectively.