Biology Reference
In-Depth Information
Figure 2.47
“Popcorn” clouds over the land of Amazonia during the dry season (June-August)
caused by release of moisture higher into the atmosphere above tall trees than from over the riv-
ers. From the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua Satel-
lite; image available on the NASA Earth Observatory site, http://earthobservatory.nasa.gov/.
Eocene of the Mississippi Embayment region, were notoriously unreliable
(Dilcher 1973), and it can only be guessed what the fi gure is in the older
literature for fossil fl oras in the tropics.
The exact number of species in the neotropical rain forest is not known,
but for tree species that reach a size of more than 10 cm dbh, the num-
ber is estimated at 11,120 (Hubbell et al. 2008). Of these, about 3248 spe-
cies have more than 1 million individuals, and 5308 species have less than
10,000 individuals. Among the latter, the extinction rate is estimated at
37-50 percent, and over the next several decades the mean total extinc-
tion rate of tree species in the Brazilian Amazon is estimated at between
20 percent (optimistic scenario) and 33 percent (nonoptimistic scenario).
Humid forest clearing between 2000 and 2005 was about 1.39 percent,
making for a 2.36 percent reduction in the area of humid tropical forest.
About 55 percent of total biome clearing occurs within only 6 percent of
the rain forest area (Latin America), with Brazil accounting for 47.8 per-
cent, or four times that of Indonesia, the next most-cleared country at
12.8 percent (Hansen et al. 2008). As Richard Black put it in a 2008 BBC
News report, “The global economy is losing more money from the disap-
