f(TEMP)f(WFPS) f(Lit q)

(a) Soil Moisture Balance and Plant Functional Types

(b) Ecosystem Production Nutrient Mineralization

Leaf Litter

Root Litter

Microbes

Soil OrganicMatter

CO2

SoilProfile Layers

Heat &WaterFlux

PREC

Grass/Crop Shrub Tree

PET

FPAR

NPP

M 0

M 1

M 2

M 3

M 0

M 1

M 2

M 3

M 0

M 1

M 2

M 3

Soil Surface

Biomass

CO2 NEP

Rh

f(TEMP)f(WFPS)f(SOLAR)

References• Ferreira, L.G. and Huete, A.R., 2004, Assessing the seasonal dynamics of the Brazilian Cerrado vegetation through the use of spectral vegetation indices, Int. J. Remote Sensing, 25(10):1837-1860.• Pinto AD, Bustamante MMC, Kisselle K, Burke R, Zepp R, Viana LT, Varella RF, Molina M. 2002, Soil emissions of N2O, NO, and CO2 in Brazilian savannas: Effects of vegetation type, seasonality, and prescribed fires.  J. Geophys. Res.-Atmos., 107. • Potter, C. S., S. Klooster, C. R. de Carvalho, V. Brooks-Genovese, A. Torregrosa, J. Dungan, M. Bobo, and J. Coughlan., 2001, Modeling seasonal and interannual variability in ecosystem carbon cycling for the Brazilian Amazon region. J. Geophys. Res.-Atmos., 106, 10,423-10,446.• Potter, C. S., S. Klooster, M. Steinbach, P. Tan, V. Kumar, S. Shekhar, C. J. R. Carvalho, 2004, Understanding global teleconnections of climate to regional model estimates of Amazon ecosystem carbon fluxes, Global Change Biology, 10, 693–703.• Varella RF, Bustamante MMC, Pinto AS, Kisselle KW, Santos RV, Burke RA, Zepp RG, Viana LT. 2004, Soil fluxes of CO2, CO, NO, And N2O from an old pasture and from native savanna in Brazil.  Ecological Applications, 14, S221.

ABSTRACTThe expansion of intensive agricultural practices into former Cerrado and

seasonal forests of the eastern Amazon has increased markedly over the past several years. Over the last 30 years an estimated 37 percent of Cerrado natural vegetation has been transformed, with more than 12 million hectares planted to crops consisting mostly of soybeans, maize, and rice. We are synthesizing measurement data and MODIS remote sensing observations at locations that represent conversion of Cerrado types and Amazon forests to intensive agricultural land use. A principal objective is to improve calibration of the NASA-CASA model and subsequently evaluate and refine a series of regional model simulation runs for these transformed ecosystems.

SYNTHESIS STRATEGYOur synthesis approach is based on the following steps:• Validate ecosystem model predictions (NASA-CASA) and their land cover inputs by comparison to tower-based and small plot measurements of net ecosystem production (NEP), trace gas fluxes, and other field-based measurement data sets from intensive field study sites.• Recommend/prioritize improvements to ecosystem models, which will incorporate intensive agricultural development and secondary forest regrowth, to better constrain source/sink estimates for atmospheric CO2 and other trace gases (N2O, NO, CO, CH4) of importance in LBA.• Use satellite observations (MODIS) EVI and FPAR to make regional modeling assessments of trace gas exchange over the past five years.

Acknowledgments

NASA-CASA MODEL(Potter et al., 2001 and 2004)

This work was supported by NASA Grants in Terrestrial Ecology LBA-ECO and Earth Observing System Interdisciplinary Science (EOS/IDS).

CERRADO TO SOYBEAN TRANSITION SCENARIOSThe Cerrado 2 site was simulated for a 80-year initialization period using the NASA-CASA (Carnegie-Ames-Stanford) model (Potter et al.,

2001 and 2004). Model inputs were MODIS 250-meter Enhanced Vegetation Index (EVI) monthly values for 2004 and NCEP reanalysis climate drivers. Following initialization of Cerrado soil C and N pools, the simulated site was cleared of standing live and litter biomass and converted to soybean (soja) cultivation (with new EVI inputs) for three years. To couple seasonal patterns of NPP to soil heterotropic respiration (Rh) of CO2 and other trace gas emissions from soil, first-order decay equations simulate exchanges of decomposing organic residue fractions remaining on site.

NEP

Rh

CO2

CHRISTOPHER POTTER, NASA Ames Research Center; MERCEDES BUSTAMANTE and ALESSANDRA KOZOVITS,

Universidade de Brasília; RICHARD ZEPP, US EPA; LAERTE FERREIRA, Universidade Federal de Goias: ALFREDO HUETE, Univ. Arizona; STEVEN KLOOSTER and MARC KRAMER, California State University Monterey Bay

LBA-ECO III Team: TG-30

MODIS 250-m EVI Inputs Representative monthly EVI values for study sites are show in the figure below. Compared to the Soybean site, the Cerrado 2 site has lower greenness values in Jan-Mar, and higher greenness values in Apr-Sep.

TG-30 SYNTHESISACTIVITIES

INITIAL MODELING RESULTSThe NASA-CASA model was driven by EVI and NCEP climate inputs to generate daily predictions of net primary production (NPP), net

ecosystem exchange of CO2, and other soil trace gas emission rates. Following conversion of Cerrado vegetation, three years of soybean cultivation were simulated (below), without the addition of fertilizer. Simulated conversion removed all standing live and dead biomass at the soil surface.

Ecosystem Carbon Balance

Synthesis Studies of Intensive Agriculture Impacts in the Amazon: Field Data, Remote Sensing, and Modeling Approaches

• Planaltina (Fazenda Rio de Janeiro) where pasture reformation was installed: 15o13’S, 47o42’W

• Cottonfield in Cristalina: 16o11’S, 47o37’W• IBGE Ecological Reserve Cerrado: 15o56’S, 47o51’ W• Cristalina farm (Fazenda Dom Bosco)

Farmer house (Sede): 16o13'14.4”S, 47o28'2.1”WSoja (Soybean): 16o13'14.4”S, 47o27'59.8”WSanta Fé (bean , sorgo, Brachiaria): 16o16'36.5”S, 47o 27'47.5”W

• Cerrado 1 (Cerrado strictu sensu, 20-50% canopy cover, with cattle): 16o16'36.5”S, 47o2747.5”W

• Cerrado 2 (without cattle): 16o17'21.2”S, 47o27'36.7”W• Pivô 3 (corn, bean, Brachiaria): 16o16'43.3”S,

47o27'05”W

FIELD SITE DATA SOURCES

INTERPRETATIONS The initial CASA model results presented here can be used to formulate several hypotheses to test in subsequent data synthesis activities for LBA-ECO III:

• Due to rapid mineralization of soil organic residues left by native vegetation, soil CO2 fluxes are elevated 2-3 fold for several years following conversion of Cerrado to soybean cultivation, making the agricultural land use in this region of Brazil a substantial source of greenhouse gas emissions.

• Soil N mineralization fluxes are elevated more than 10 fold for several years following conversion of Cerrado to soybean cultivation.

• Not accounting for fertilizer amendments, soil NO fluxes are elevated at least 3 fold for several years following conversion of Cerrado to soybean cultivation, making the agricultural land use in this region of Brazil a substantial source of reactive trace gas emissions.

CASA Model Modifications

• Planting and harvest times: The primary growing season in Mato Grosso/Goias is September-March. Soja are planted during October-December for harvest during February-May.• Intercropping: Corn is frequently planted as a second crop on soja that harvested before early March. Second-crop corn is planted by early March for harvest during August-September.• Tillage: No-till is the common management practice in Soja. • Fertilizer application: Soja requires large amounts of lime and phosphorus compared to other crops such as corn or wheat. Typical application rates are: 7 kg N/ha and 76 kg P2O5/ha (Source: FAO, 2004, Fertilizer Use by Crop in Brazil).

Nitrogen Trace Gas Emission from Soils

Cerrado | Soybean --------------------> Cerrado | Soybean ------------------>

Several data analysis activities are underway to better understand the impact of intensive agricultural expansion on former Cerrado and seasonal forest areas of the eastern Amazon:

• Survey of common crop rotation and fertilizer application practices.

• Evaluation of changes in soil properties, nutrient pathways, and moisture dynamics in transition systems.

• Characterization of EVI seasonal profiles for transition systems.