@Article{MouraGHWSANLWPOMA:2017:SpAnAm,
author = "Moura, Yhasmin Mendes de and Galv{\~a}o, L{\^e}nio Soares and
Hilker, T. and Wu, J. and Saleska, S. and Amaral, C. H. do and
Nelson, B. W. and Lopes, Aline Pontes and Wiedeman, K. K. and
Prohaska, N. and Oliveira, R. C. and Machado, Carolyne Bueno and
Arag{\~a}o, Luiz Eduardo Oliveira e Cruz de",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {University of
Southampton} and {University of Arizona} and {University of
Arizona} and {Universidade Federal de Vi{\c{c}}osa (UFV)} and
{Instituto Nacional de Pesquisa da Amaz{\^o}nia (INPA)} and
{Instituto Nacional de Pesquisas Espaciais (INPE)} and {University
of Arizona} and {University of Arizona} and {Empresa Brasileira de
Pesquisa Agropecu{\'a}ria (EMBRAPA)} and {Instituto Nacional de
Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas
Espaciais (INPE)}",
title = "Spectral analysis of amazon canopy phenology during the dry season
using a tower hyperspectral camera and modis observations",
journal = "ISPRS Journal of Photogrammetry and Remote Sensing",
year = "2017",
volume = "131",
pages = "52--64",
month = "Sept.",
keywords = "Amazon, Dry season, Hyperspectral remote sensing, Leaf flush,
Phenology, Seasonality, Tropical species.",
abstract = "The association between spectral reflectance and canopy processes
remains challenging for quantifying large-scale canopy
phenological cycles in tropical forests. In this study, we used a
tower-mounted hyperspectral camera in an eastern Amazon forest to
assess how canopy spectral signals of three species are linked
with phenological processes in the 2012 dry season. We explored
different approaches to disentangle the spectral components of
canopy phenology processes and analyze their variations over time
using 17 images acquired by the camera. The methods included
linear spectral mixture analysis (SMA); principal component
analysis (PCA); continuum removal (CR); and first-order derivative
analysis. In addition, three vegetation indices potentially
sensitive to leaf flushing, leaf loss and leaf area index (LAI)
were calculated: the Enhanced Vegetation Index (EVI), Normalized
Difference Vegetation Index (NDVI) and the entitled Green-Red
Normalized Difference (GRND) index. We inspected also the
consistency of the camera observations using Moderate Resolution
Imaging Spectroradiometer (MODIS) and available phenological data
on new leaf production and LAI of young, mature and old leaves
simulated by a leaf demography-ontogeny model. The results showed
a diversity of phenological responses during the 2012 dry season
with related changes in canopy structure and greenness values.
Because of the differences in timing and intensity of leaf
flushing and leaf shedding, Erisma uncinatum, Manilkara huberi and
Chamaecrista xinguensis presented different green vegetation (GV)
and non-photosynthetic vegetation (NPV) SMA fractions; distinct
PCA scores; changes in depth, width and area of the 681-nm
chlorophyll absorption band; and variations over time in the EVI,
GRND and NDVI. At the end of dry season, GV increased for Erisma
uncinatum, while NPV increased for Chamaecrista xinguensis. For
Manilkara huberi, the NPV first increased in the beginning of
August and then decreased toward September with new foliage.
Variations in red-edge position were not statistically significant
between the species and across dates at the 95% confidence level.
The camera data were affected by view-illumination effects, which
reduced the SMA shade fraction over time. When MODIS data were
corrected for these effects using the Multi-Angle Implementation
of Atmospheric Correction Algorithm (MAIAC), we observed an EVI
increase toward September that closely tracked the modeled LAI of
mature leaves (35 months). Compared to the EVI, the GRND was a
better indicator of leaf flushing because the modeled production
of new leaves peaked in August and then declined in September
following the GRND closely. While the EVI was more related to
changes in mature leaf area, the GRND was more associated with new
leaf flushing.",
doi = "10.1016/j.isprsjprs.2017.07.006",
url = "http://dx.doi.org/10.1016/j.isprsjprs.2017.07.006",
issn = "0924-2716",
language = "en",
urlaccessdate = "04 maio 2024"
}