@InProceedings{CardosoOlivNobr:2010:CoDeFi,
author = "Cardoso, Manoel Ferreira and Oliveira, Gilvan Sampaio de and
Nobre, Carlos Afonso",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de
Pesquisas Espaciais (INPE)}",
title = "Combined deforestation and fire occurrence in long-term models of
forests and savannas in the Brazilian Amazonia",
booktitle = "Proceedings...",
year = "2010",
organization = "The Meeting of the Americas.",
publisher = "AGU",
keywords = "biosphere, atmosphere interactions, modeling, eco-hydrology,
land.",
abstract = "According to climate and hydrological conditions, large tropical
areas would potentially be covered by forests. Remote sensing and
field surveys, however, show how these regions may differ from
their potential original states because land use, such as logging,
agriculture and pastures. Related processes also contribute to the
replacement of forests by secondary and degraded vegetation, and
to the establishment of savannas. Fires are such a process
normally associated to the current land-use practices in the
tropics. Because savannas are adapted to fires and benefit from
their occurrence, forest-to-savanna transitions are potentially
very stable near deforestation areas. Here we present a method to
account for deforestation and fires on the distribution of
tropical and seasonal forests and savannas in the Brazilian
Amazonia, and underline some strategies for implementing it in
long-term vegetation models. We analyzed soil-hydrology and fires
occurrence data together with the results from the potential
vegetation model CPTEC-PVM2, and explored two factors used to
determine the potential distribution of major biomes in that
model. One is a soil-moisture seasonality index (D) which is lower
(higher) for places where the soil presents longer (shorter) dry
periods. Other is an above-ground wetness index (H) which is lower
(higher) for longer (shorter) periods of dry atmospheric
conditions. The analysis indicated the most common values for both
indexes in areas potentially covered by tropical forests in the
Brazilian Amazonia that had low, medium and high fire activity in
the years 1998-2005 according to active-fire detections with the
Tropical Rainfall Measuring Mission - Visible and Infrared Scanner
(TRMM-VIRS). For each fire-activity class, we determined the
distribution of values for both indexes and found the values below
which deforestation/fire degradation were relatively more
frequent. We now plan to use these relations when accounting for
deforestation/fires in projections of the spatial distribution of
the major biomes in the region. For that, we selected and discuss
the following strategy that we consider appropriated. First, we
assume that land-use dynamics and policy currently observed in the
Brazilian Amazon will remain in the future. Second, we consider
that deforestation/fires will affect forests only in grid cells of
tropical and seasonal forests that are located adjacent (<150km)
to savannas, because the access to the forests is facilitated by
the savannas where fires are also a natural feature. In summary,
if a place projected to be covered by tropical or seasonal forest
presents both indexes H and D below certain thresholds, and the
area is adjacent to a savanna, then tropical forest will be
adjusted to seasonal forest. In case of a seasonal forest it will
be adjusted to savanna. Although our method may represent an
underestimation of fire effects by not considering direct
transitions from tropical forests to savannas, it allows for
quantifying changes in vegetation cover including human factors,
and based on simple general relations derived using data from the
region.",
conference-location = "Foz do Igua{\c{c}}u",
conference-year = "8-12 Aug. 2010",
language = "en",
targetfile = "Cardoso_Combined.pdf",
urlaccessdate = "15 jun. 2024"
}