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the study area, among which 32.04 % is converted into the pasture and 67.96 % is
transitioned into the woodland. The secondary forest decreases by 4.33 % in the
study area, among which 19.40 % is transitioned from forest into pasture and
80.60 % into the woodland. Furthermore, the proportions of each cell in which
primary forest is converted to pasture and woodland range from 0 to 56.51 % and
from 0 to 20.70 % separately from 2005 to 2100, in comparison to those of the
secondary forest range from 0 to 37.70 % and from 0 to 15.31 %, respectively.
Figure 7.12 provides the geographical distribution of changed forest land. The
degraded and transitioned grid cells primarily distribute in the periphery of the
entire Amazon, or along the rivers. Particularly, most grid cells in which forests
are converted into pasture are mainly located in the northwest part of the study
area, where contains a great deal of water resource supplied by the dense water
network. By contrast, the cells in which forest is converted into cropland are
principally distributed in the most disturbed and populated area, especially the
transition zones between forests and other land cover types.
7.3.2.2 Heat Fluxes
The yearly averaged sum of sensible and latent heat flux serves as an indicator
for estimating the energy exchange between land surface and atmosphere during
2090-2100. Generally, based on the model analysis, deforestation will cause a
reduction in surface heat flux with approximate 5 W/m 2 per month (Fig. 7.13 ).
In the control simulation, the surface heat flux in the east is greater than that in
the west, but the eastern area will see a decline in the deforestation simulation.
This progressive decrease in the total heat flux illustrates the importance of
increase in surface albedo and radiation caused by deforestation. Specifically, the
annual average sensible heat flux will increase to some extent, especially in the
west region covering most deforested areas during the period of 2090-2100,
while the latent heat flux shows a significant downward trend in the same period.
Such spatial gradient of heat flux will increase the convection by generating a
thermally driven circulation, leading to rising of the sensible heat flux over the
west part and falling over the east part, which will redistribute the temperatures.
7.3.2.3 Precipitation and Temperature
On the whole, the annual domain-averaged precipitation will decrease, while the
temperature will increase during the simulation period. Deforestation in Brazilian
Amazon will induce a monthly reduction in precipitation (1.05 mm) and a monthly
increase in surface temperature (0.12 C). The Fig. 7.13 also shows that the
deforestation will cause a significant precipitation reduction in rainy season, but a
slight decrease in dry season. Correspondingly, the surface temperature nearly
increases to a large extent in rainy season and moderately goes up to a higher level
in dry season.
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