@Article{CarreirasJoneLucaShim:2017:MaMaLa,
author = "Carreiras, Jo{\~a}o M. B. and Jones, Joshua and Lucas, Richard M.
and Shimabukuro, Yosio Edemir",
affiliation = "{University of Sheffield} and {Aberystwyth University} and
{University of New South Wales} and {Instituto Nacional de
Pesquisas Espaciais (INPE)}",
title = "Mapping major land cover types and retrieving the age of secondary
forests in the Brazilian Amazon by combining single-date optical
and radar remote sensing data",
journal = "Remote Sensing of Environment",
year = "2017",
volume = "194",
pages = "16--32",
month = "June",
keywords = "Age of secondary forests, ALOS PALSAR, Amazon, Landsat TM, Random
forests, Tropical secondary forests.",
abstract = "Secondary forests play an important role in restoring carbon and
biodiversity lost previously through deforestation and degradation
and yet there is little information available on the extent of
different successional stages. Such knowledge is particularly
needed in tropical regions where past and current disturbance
rates have been high but regeneration is rapid. Focusing on three
areas in the Brazilian Amazon (Manaus, Santar{\'e}m, Machadinho
d'Oeste), this study aimed to evaluate the use of single-date
Landsat Thematic Mapper (TM) and Advanced Land Observing Satellite
(ALOS) Phased Arrayed L-band Synthetic Aperture Radar (PALSAR)
data in the 20072010 period for i) discriminating mature forest,
non-forest and secondary forest, and ii) retrieving the age of
secondary forests (ASF), with 100 m × 100 m training areas
obtained by the analysis of an extensive time-series of Landsat
sensor data over the three sites. A machine learning algorithm
(random forests) was used in combination with ALOS PALSAR
backscatter intensity at HH and HV polarizations and Landsat 5 TM
surface reflectance in the visible, near-infrared and shortwave
infrared spectral regions. Overall accuracy when discriminating
mature forest, non-forest and secondary forest is high (9596%),
with the highest errors in the secondary forest class (omission
and commission errors in the range 46% and 1220% respectively)
because of misclassification as mature forest. Root mean square
error (RMSE) and bias when retrieving ASF ranged between 4.34.7
years (relative RMSE = 25.532.0%) and 0.040.08 years respectively.
On average, unbiased ASF estimates can be obtained using the
method proposed here (Wilcoxon test, p-value > 0.05). However, the
bias decomposition by 5-year interval ASF classes showed that most
age estimates are biased, with consistent overestimation in
secondary forests up to 1015 years of age and underestimation in
secondary forests of at least 20 years of age. Comparison with the
classification results obtained from the analysis of extensive
time-series of Landsat sensor data showed a good agreement, with
Pearson's coefficient of correlation (R) of the proportion of
mature forest, non-forest and secondary forest at 1-km grid cells
ranging between 0.970.98, 0.960.98 and 0.840.90 in the 20072010
period, respectively. The agreement was lower (R = 0.820.85) when
using the same dataset to compare the ability of ALOS PALSAR and
Landsat 5 TM data to retrieve ASF. This was also dependent on the
study area, especially when considering mapping secondary forest
and retrieving ASF, with Manaus displaying better agreement when
compared to the results at Santar{\'e}m and Machadinho d'Oeste.",
doi = "10.1016/j.rse.2017.03.016",
url = "http://dx.doi.org/10.1016/j.rse.2017.03.016",
issn = "0034-4257",
language = "en",
targetfile = "carreiras_mapping.pdf",
urlaccessdate = "27 abr. 2024"
}