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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
CHANGE ANALYSIS OF THE SPECTRAL CHARACTERISTICS OF RUBBER TREES
AT CANOPY AND LEAF SCALES DURING THE BRAZILIAN AUTUMN
C. H. Amaral * *, T. I. R. Almeida*, G. C. M. Quitério, M. N. Alves ©, C. R. Souza Filho"
"Institute of Geosciences, University of Sáo Paulo, Rua do Lago 562, 05508-080, Sáo Paulo, SP, Brazil - (chamaral,
talmeida) @usp.br
Institute of Geosciences, University of Campinas, Rua Jodo Pandi Calôgeras 51, 13083-870, Campinas, SP, Brazil -
(giuliana, beto) @ige.unicamp.br
‘Multidisciplinary Center of Chemical, Biological and Agricultural Research, University of Campinas, P.O. BOX 6171,
13081-970, Campinas, SP, Brazil - mnopper@cpgba.unicamp.br
Commission VIII, WG VIII/7
KEY WORDS: Forestry, spectral, weather, comparison, hyperspectral, high resolution.
ABSTRACT:
The objective of this work is to investigate the hyperspectral remote sensing potential to detect spectral changes undergone by clones
of two rubber trees within Brazilian Autumn, with decrease of rain, temperature and photoperiod between May and June. Indirectly,
we also analyze the ability of the data to help discriminating the clones at two dates in autumn. The average canopy spectra of the
stands were obtained with two overpasses of the ProSpecTIR-VS airborne hyperspectral sensor (357 bands between 400-2,500 nm:
spatial resolution of 1m) by 14" May and 17" June, in 2010 year. Additionally measurements of leaf spectra were taken in the same
dates, but in the 2011 year. Considering the analysis of the spectra measured from the three stands, this indicates that spectral
differences in the VIS (400-700 nm) region are of genetic origin and occur regardless of environmental conditions and period of data
collection. In the NIR (700-1,300 nm) range, the environmental factors predominate in the two periods of data collection. The SWIR
(1,300-2,500 nm) displayed the largest differences between the months of data collection. In May, the relationship between stands
indicated the prevalence of environmental aspects. However, in June, the stands and clones spectral behaviour indicates that as the
temperature, the rainfall and the photoperiod are lower closer to winter, the SWIR can be effectively used to discriminate and map
these clones separately.
1. INTRODUCTION
Belonging to Euphorbiaceae family, the genus Hevea, native
from Amazon region presents 11 species, and its main
historical-commercial representative is the Hevea brasiliensis
(Wild ex Adr. de Juss) Muell-Arg. Its domestication started
about 130 years ago (Gongalves et al, 2006), although the
interest in studying its cultivation within the state of Säo Paulo
- southeast region of Brazil — aroused only in 1951 when the
country started to export rubber (latex) again. Its cultivation
success in the State of Sáo Paulo — where the edaphoclimatic
conditions are very different from the Amazon region (its
original site), required the application of genetically improved
plants as well as the test of several cultivars, such as the ones
Which are being studied here.
There are not many works within the literature which approach
the studies of rubber trees by using remote sensing techniques.
Nandris et al. (1985), when utilizing near infra-red, aimed to
verify the damages caused by the parasites of rubber trees’ roots
in Ivory Coast. Suratman et al. (2002 and 2004), by using
TM/Landsat images, aimed the attributes modeling — such as the
volume, area and age — of rubber tree plantations in Malaysia.
There are even other works which studied the spectral
behaviour of genetic and environmental variations with species
of the same genus as well as with different phenotypes of the
Same specie, as observed at Castro & Sanchez-Azofeifa (2008)
and at Martin & Asner (2007) respectively. Using the
ProSpecTIR-VS sensor, the same one that is used in this
=... ©:
s Corresponding author. This is useful to know for communication with the appropriate person in cases with more than one author.
research, Ustin (2008) held a pioneer work on the senescence
recognition of Pine's different species.
The application of field spectrometer — in order to compare and
validate the spectral data obtained by imaging, and considering
that there is, in these cases, influence of canopy structure, leaf
angle, ligneous material and soils — is a recent accomplishment
by Clark et al. (2005) and Asner & Martin (2008), done with
species of tropical rainforest. However, nothing with this
approach was found in the literature for the genus Hevea.
Using hyperspectral images from the ProSpecTIR-VS airborne
sensor as well as leaf measures taken from the ultraspectral
ASD FiedSpec-3 Hi-Res spectrometer, the aim of this research
was to verify the remote detection potential of the changes
suffered by the clones late in the autumn with the drop of all:
average rainfall, average temperature and photoperiod.
Indirectly, we also analyze the ability of the data to help
discriminating the clones at two dates in autumn.
2. MATERIAL AND METHODS
2.1 Study area and object
The study area is located at the coordinates (central) 22? 47'
52.31" S e 47? 6' 26.95" W, at 590m above the sea, at the
University of Campinas experimental farm in Paulínia city, in
the State of Sáo Paulo, southeast region of Brazil. It presents
1,972.0m?, occupied by two stands of the PB235 clone, as well
as, one stand from the GTI clone (Figure 1). The climate for
