Chicago, Illinois/US, 12-13 Jun 2012
Water and carbon fluxes in forested
and crop areas in Brazil
Humberto Rocha
1. Description of climate and croplands
2. Measurements of ET, GEP and
albedo
3. Deforestation feedback in rainfall
4. Peak flows and load discharge in
cropland streams
1. Climate
3
Critical
patterns of
water
availability
Fonte: ANA –
Conjuntura
Recursos Hídricos
do Brasil
2. Main crops – area, productivity
Sugar cane
Soybean
Corn
Rice
The forest protection code legislation (1965) statements:
Legal reserve (RL)
Permanent Protected Areas (APP)
Law enforcement (2005)
3. Flux tower sites in forested areas
Flux tower over sugar cane, cerrado and eucaliptus plantation
(MogiGuaçu watershed – state of São Paulo)
ET and GEP across a forest-cerrado
biome transition
Pc Pc -1
max
1
0.8
0.6
0.4
0.2
(fraction of max) with days since
start of dry season
Equatorial forests
Equatorial forests
Tropical
seasonal
forests
Savanna &
Pasture
GEP GEP-1
max
Evapotranspiration
(fraction of max)
0Gross Ecosystem Productivity
30 60 90 120 150 180 210 240 270 300 330 360
1
0.8
0.6
0.4
Tropical
seasonal forests
0.2
0
Savanna & Pasture
30 60 90 120 150 180 210 240 270 300 330 360
No. days since dry season starts
CO2 flux – tropical forest Santarem (k83 site)
CO2 fluxes: annual sum is
prone to uncertainties
Miller 2004, Ecol Appl; Goulden 2004 Ecol Appl, 2006 JGR
Saleska 2003, Science; Hutyra 2007 JGR
Reco ~ nighttime flux
GPP ~ daytime flux – Reco
•
•
High numbers are observed in the
tropics
Miller 2004, Ecol Appl
Reco u*filtered
Reco
Dry season
Wet season
sink
loss
... but leads to a reasonable interpretation of
seasonality
GPP
The ability of forest vegetation to reach soil
moisture and depend on its variability is a key step
to understand the ecosystem resilience
Soil moisture pumped from trees at
different depths (% of daily totals)
Soil moisture
measurement
with Time
Domain
Reflectometry
Dry season 84%
at 7m
Rainfall
inhibition
Previous modelling sudies
suggested that large scale
deforestation in Amazonia may
lead to a reduction in rainfall and
impact the ecosystem, but the
investigation over small areas is
still a less known matter.
This numerical experiment used:
BRAMS atmospheric model w/
3 nested grids (64,32,08 km of
horizontal resolution)
Deforestation strip
Rainfall
enhancement
Changes
varied from
 10 to 30 %
Global Solar Albedo over sugar cane plantation – measurements in 3
different harvest types (Cabral et al 2011, and unpublished data)
Harvest
(bars)
1997-1999 – harvest in Apr/May,
dry leaves burning, manual
harvest (unpublished)
2001-2002 harvest in Sep/Out,
green harvest w/ mulching
(unpublished)
2005-2007 harvest in Apr/May,
burning dry leaves, mechanical
harvest (Cabral et al 2011)
Média no período chuvoso
Measured mean ET and above
canopy temperature
(Source: Tatsch, J. (2012) PhD
thesis USP and unpublished data)
Temperatura do ar acima da copa (oC)
cana-de-açúcar
Cerrado
eucalipto
30
28
26
24
22
20
18
0
3
6
9
12 15 18 21 24
hora do dia
ET simulatied w/ modified-SiB2 model)
Rainfall runoff modelling (DBHM/SiB2) at MogiGuaçu
watershed. Source: Tatsch, J. (2012) PhD thesis USP
Current Land Cover
APP_reforest (Permanent Protected areas)
Cerrado
lower
sugar cane
higher
Eucaliptus
intermediate
Final statements
Brazil ranks 8th in global economy
- Agrobusiness ~ 1/3 GDP and ½ jobs
Very competitive ethanol (10 units of energy/1 unit of
fossil fuel used)
Large potential crop expansion with strong concern on
environmental sustainability
University of São Paulo seeks for partnerships which helps to quantify the
ecosystem services and identify ways for their economical internalization
with regional and global benefits
Thanks – contact HUMBERTO@MODEL.IAG.USP.BR