Undisturbed tropical forest 10 years after deforestation
Carbon sink Carbon source
Total C absorption
25.1 Total C emission
30.4
Total C emission
(by photosynthesis)
24.5
(by respiration)
Burning, decay of slash
Respiration and soil erosion
6.8
18.3
Total C absorption
C stored in
(by photosynthesis)
12.3
180
above-ground
biomass
C stored in
Carbon fluxes and stocks
43
above-ground
(Tonnes of C per ha
per
biomass
year for fluxes, tonnes of
C per ha for stocks)
C stored in
C stored in
12
below-ground biomass
below-ground biomass
64
C stored
C stored
below-ground Note: flux values are reported
below-ground
(soil and biomass)
150 as a 10 year average.
(soil and biomass) 226
Source: Malhi and Grace, 2000.
Source: Achard et al., 2004.
Globally, tropical forests are considered to be currently carbon tween 6.5 and 14.8 million ha per year and these deforestation
sinks, with recent research indicating an annual global uptake activities alone release an estimated 0.8–2.2 Gt carbon per year
of around 1.3 Gt of carbon. Of this forests in Central and South into the atmosphere (Houghton 2005a). Deforestation not only
America are estimated to take up around 0.6 Gt C, African for- reduces vegetation carbon storage but can also significantly re-
ests somewhat over 0.4 Gt and Asian forests around 0.25 Gt duce soil carbon stocks.
(Lewis et al. 2009). To put this figure into context, the carbon
uptake of tropical forests is equivalent to approximately 15% In addition to deforestation, tropical forests are also being used
of the total global anthropogenic carbon emissions. Tropical for the extraction of timber and other forest products. This
forests therefore make a significant contribution to climate leads to degradation of the forest and is estimated to contribute
change mitigation. globally to a further emission of around 0.5 Gt carbon per year
into the atmosphere (Achard et al. 2004).
HUMAN USE AND CONVERSION OF
TROPICAL FORESTS In logging of tropical moist forests, typically only one to twenty
Tropical forests are being converted to industrial and agricul- trees per ha are harvested. Conventional logging techniques
tural (food and biofuel production) land uses at high rate. The damage or kill a substantial part of the remaining vegetation
causes for tropical deforestation are complex and range from during harvesting, resulting in large carbon losses. Reduced-
underlying issues of international pressure and poor gover- impact logging techniques can reduce carbon losses by around
nance to local resource needs (Geist and Lambin 2001). Global 30% during forestry activities compared with conventional
tropical deforestation rates are currently estimated to be be- techniques (Pinard and Cropper 2000).
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