Environmental Engineering Reference
In-Depth Information
reserved forests, and other wooded areas) was at least 25 Gt, and their annual NPP
was about 4.5 Gt (Joyce et al. 1995). This means that the removal of all woody
phytomass was equal to only about 1% of the existing woody phytomass and on
the order of 6% of the annual forest NPP.
Analogical calculations have been relatively easy to make for Canada, Germany,
France, or Japan, but only the latest monitoring advances have resulted in fairly
reliable stocktaking for the tropical countries. When Gibbs et al. (2007) surveyed
the totals of national carbon stock estimates in tropical forests based on compila-
tions of harvest data as well as on forest inventories published between 2002 and
2007, they found that the differences between the lowest and highest estimates
were commonly two- or even threefold. These estimates included 1.9-5.1 Gt C
for Mozambique, 3.6-11.8 Gt C for Angola, 2.5-9.2 Gt C for Bolivia, and 2.5-
11.5 Gt C for Colombia. For the three countries with the largest areas of tropical
forests, Brazil, Congo, and Indonesia, the differences were respectively 1.5-, 1.8-,
and 2.5-fold, and in absolute terms the aggregate difference amounted to more
than 60 Gt C.
These uncertainties have been greatly reduced by a new mapping of phytomass
stored in 2.5 Gha of tropical forests (Saatchi et al. 2011). The study combined data
from nearly 4,100 inventory plots with satellite Lidar (light detection and ranging)
samples of forest structure and with high-resolution (1 km) optical and microwave
imagery to estimate the global tropical forest carbon stock of 247 Gt C, with nearly
80% (193 Gt C) aboveground and the rest in roots. Latin American forests store
49% of the total, sub-Saharan Africa accounts for 25%, and Southeast Asia accounts
for 26%. Phytomass density for growth with 30% canopy cover (with the global
area of 1.67 Gha) averaged 124 t C/ha, ranging from just 80 t C/ha in Angola to
180 t C/ha in Malaysia.
