de Oliveira, M.F. and Marenco, R.A. 2019.
"Gas exchange, biomass allocation
and water-use efficiency in response to
elevated CO2 and drought in andiroba
(Carapa surinamensis, Meliaceae)"
iForest 12: 61-68.
SUMMARY:
Some climate models
project the Amazon region
could experience periods
of prolonged drought
in the future.
Models are consistently wrong
for global projections -- regional
projections are even worse.
But they led to de Oliveira
and Marenco (2019) trying to:
"assess the effect
of elevated CO2 (eCO2)
and drought on
photosynthetic rates,
water-use efficiency,
and biomass allocation
in andiroba
(Carapa surinamensis)."
Andiroba tree growth benefits
from rising CO2 concentrations,
which also improves their use of water,
especially during times of drought.
Andiroba was selected
because it is frequently used
in reforestation projects due to
its production of high quality wood
and oil ( carapa oil ), which is
extracted from its seeds.
DETAILS:
Drought negatively impacted
andiroba growth, elevated CO2
improved growth.
An elevated CO2 environment
increased growth rates
+39% higher
under well-watered conditions
and +60% higher
under drought conditions.
Total dry matter increased +43%
under well-watered conditions
and increased +98% under
drought conditions.
Total water use was reduced
under elevated CO2 conditions
compared with ambient CO2.
Trees used less water
and produced more mass
with elevated CO2 treatment.
Their water use efficiencies
were greatly enhanced
by elevated CO2.
Water use enhancement
was +188% under
well-watered conditions
and +262% under
drought conditions.
The two Brazilian researchers
exposed six-month-old
andiroba saplings
to ambient CO2 ( 400 ppm ),
and elevated CO2 ( 700 ppm ),
under either well-watered
( soil water content
kept at 100% of field capacity )
or drought conditions
( soil water content
kept at 50% of field capacity )
for 163 days.
The experiment was conducted
at the National Institute for Research
in the Amazon, Manaus, Brazil
in controlled-environment chambers.
