Geography Reference
In-Depth Information
mainly due to the increase of surface albedo caused by boreal deforestation, which
offset the warming effect due to evapotranspiration reduction.
The results of this study basically reveals the impacts of boreal deforestation on
regional climate changes, but there are still some uncertainties about the influence of
the future land cover change since only biogeophysical effects were taken into
consideration, without considering the biochemical effects through some other key
influencing factors, such as carbon emission. Since the impacts of land cover change
are very complex, it is still necessary to carry out more in-depth researches on a series
of issues, such as combination of biochemical and biophysical models, which take
both the biogeophysical and biogeochemical processes into account. In addition,
there are still some aspects that should be improved to better detect the impacts of
deforestation on climate changes. First, it is still necessary to further explore the data
assimilation methods to harmonize the data from different sources. Second, there are
many factors that may influence the climate change, and it is necessary to do some
sensitivity experiments to detect the main factors and minimize the uncertainties.
7.3 Potential Impacts of Future land Surface Changes
on Regional Climate over the Brazilian Amazon
Forests, covering more than 30 % of terrestrial land (Deng et al.
2010
), mainly
comprise tropical, temperate, and boreal types from which provide invaluable
ecological, socioeconomic, and mental public goods and services for humanity.
Among these forest types, tropical forest occupies nearly 20 % of total forest land
area, appropriates more than 30 % of net primary production (NPP) in the ter-
restrial ecosystem. This outstanding biomass can sequester a great deal of CO
2
,
maintaining above 25 % on land surface (Bonan
1997
), which doubles or triples
that of temperate and boreal forests (Malhi et al.
2008
). Well-functioned tropical
forests could effectively accelerate the evapotranspiration rate, cool the atmo-
spheric temperature, and increase the rainfall. Some earlier experimental simula-
tions in which the tropical forest was entirely replaced with less vegetated lands
(Bonan
1997
; Negri et al.
2004
) suggested that these changes would induce
slightly unstable in surface temperature, in comparison to the decrease of pre-
cipitation, evapotranspiration, and soil moisture. The tropical deforestation will
also reduce the cloud cover caused by the increase of surface albedo and decrease
of surface roughness. Though tropical forest could mitigate surface warming
through considerable evaporative cooling effect, the temperature would increase if
the surface albedo rose to a large extent induced by deforestation, which would
offset the water and energy exchange feedback effects, compared with the
reduction of convection and precipitation (Phillips et al.
2009
). Therefore, no
debate of this issue would be complete without taking the tropical forest as a
significant component into account in climate change researches.
