Crynodeb
In quantifying the carbon budget of the Amazon
region, temporal estimates of the extent and age
of regenerating tropical forests are fundamental.
However, retrieving such information from re
mote-sensing data is difficult, largely because of
spectral similarities between different successional
stages and variations in the reflectance of forests
following different pathways of regeneration. In
this study, secondary-forest dynamics in Brazilian
Amazonia were modeled for the 1978-2002 period
to determine area and age on a grid basis. We
modeled the area, age, and age class distribution
of secondary forests using empirical relationships
with the percentage of remaining primary forest,
as determined from large-area remote-sensing
campaigns (the Pathfinder and Prodes projects).
The statistical models were calibrated using de
tailed maps of secondary-forest age generated for
seven sites in the Brazilian Legal Amazon. The
area-age distribution was then specified from
mean age by a distribution assumption. Over the
period 1978-2002, secondary-forest area was
shown to have increased from 29,000 to 161,000
km2 (that is, by a factor of 5). The mean age in
creased from 4.4 to 4.8 years. We generated a time
series of secondary-forest area fractions and suc
cessional stages that provides wall-to-wall cover
age of the Brazilian Amazon at a spatial resolution
of 0.1 decimal degrees (approximately 11 km).
Validation against reference data yielded root
mean squared errors of 8% of the total area for
estimate of secondary-forest area and 2.4 years for
mean secondary-forest age. Using this approach,
we provide the first published update on the state
of secondary forests in Amazonia since the early
1990s and a time series of secondary-forest area
over the 2 5-year period.
Iaith wreiddiol | Saesneg |
---|---|
Tudalennau (o-i) | 609-623 |
Nifer y tudalennau | 15 |
Cyfnodolyn | Ecosystems |
Cyfrol | 9 |
Rhif cyhoeddi | 4 |
Dyddiad ar-lein cynnar | 31 Mai 2006 |
Dynodwyr Gwrthrych Digidol (DOIs) | |
Statws | Cyhoeddwyd - 01 Meh 2006 |