The LBA Project: Nutrient Cycles and Trace
Exchange in the Cerrado of Central Brazil

Richard Zenr>1
Mercedes

Burke1, Marirosa Molina1, Dan Markewitz2
", Alessandra Kozovits3, Alexandre Pinto3

iORD/NERL/ERD, Athens GA
2University of Georgia, Athens GA
3Departamento de Ecologia, Universidade de Brasilia, Brasilia, Brazil
Co-sponsored by USEPA and fne National Aeronautics and Space Administration



A team of U.S. Environmental Protection
Agency (U.S. EPA) and Universidade de
Brasilia (UnB) ecologists is part of the Large
Scale Biosphere-Atmosphere Experiment in
Amazonia (LBA). The LBA project was
created through an international cooperative
agreement and includes participants from
Brazil, other Amazonian countries, the U.S.,
and European nations. The LBA participants
have conducted research at the atmospheric
and soil levels at locations distributed
throughout the Amazonian rain forest and the
Cerrado (Figure 1). The Cerrado of central
Brazil (Figure 2) is one of the largest
savannah regions on earth. The "stressors"
affecting ecosystems in this region, including
deforestation, fire, soil degradation, unwise
agricultural practices, climate change, and
urbanization, are also experienced in many
U.S. ecosystems (Figure 3). Intense
agricultural activities, such as land clearing for
soybean cultivation and cattle farming, are
rapidly changing the Cerrado. U.S. EPA and
UnB scientists have been collaborating in
central Brazil (Figure 1) to determine how
several of these stressors are affecting soil
nutrient cycling, decomposition, and the soil-
atmosphere exchange of carbon- and
nitrogen-containing trace gases. The research
is contributing data and scientific
understanding for the development of models
that describe these stressor-ecosystem
interactions.

Figure 5. Wetting produces intense, short-
lived pulses of nitric oxide emissions from
dry Cerrado soils.

Figure 6, Effect of different fertilization
treatments on lipids that indicate the microbial
community structure in Cerrado soils.

U.S. EPA/UnB researchers have focused on
the effects of fire and land use change on (1)
soil-atmosphere fluxes of gases that have
greenhouse warming potential (carbon
dioxide, nitrous oxide) and that affect air
quality (carbon monoxide, nitric oxide), (2)
stream water quality (Figure 4) and (3)
changes in soil microbial community structure.
Some of the major results to date indicate that
(1) wetting produces intense, short-lived
pulses of nitric oxide emissions from dry
Cerrado soils, (Figure 5) (2) soil carbon
dioxide emissions correlate with soil moisture
levels, (3) decomposition of nonliving plant
matter at the soil surface is a significant
carbon monoxide source, and (4) soil microbial
community structure and size are significantly
affected by fertilization practices, seasonality,
burning regime, and land use (Figure 6). The
research has led to development of effective
interactions between Brazilian and U.S. EPA
scientists providing a springboard for the
initiation of actions that protect and remediate
the environment in both countries.

Figure 1, Sites included in the Large Scale
Biosphere-Atmosphere Experiment in
Amazonia (LBA). The EPA-UnB project is
located near Brasilia, the capital of Brazil.

Figure 3. The Cerrado is a region of rapid
land conversion, where fire is one of the most
common tools utilized to clear land for both
pasture and crop establishment.

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DISCLAIMER: Although this work was reviewed by EPA and approved for presentation, it may not necessarily reflect official Agency policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

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