fiber, shelter, and numerous other purposes. The advent of agriculture supplanted
trees with crops. Other human deforestations include creating a defensive “field of
fire” around habitations and fortifications. Historically, many more trees have been
cut than replanted so forests have become depleted over time. Deforestation implies
that the change is for long time periods in which forest has been converted to
another land use (e.g., urban or agriculture).
Anthropogenic deforestation has been a significant imprint on landscapes for a
very long time. Here, four cases may be considered: First, the cedars of Lebanon
(Cedrus libani) are referenced in the Bible. Found in mountainous areas near the
Mediterranean, these 40 m tall trees were renowned in ancient times for ship
masts, building timbers, and resin formummification. Wealthy, but tree-poor
Phoenician, Egyptian, and Mesopotamian civilizations cut and transported the
wood hundreds of kilometers and this led to depletion. By modern times the wood
was used for railroad ties and the species is now all but extinct except in protected
reserves. Second, Easter Island (Rapa Nui) in the southeastern Pacific Ocean has
undergone extensive deforestation in the last three-and-a-half centuries. This has
been variously attributed to cooling during the Little Ice Age, the cutting of trees
by its residents, and the deleterious effects of introduced animals on the native tree
species. Third, Great Britain once had an extensive forest cover. The British domi-
nance of the seas and dependence on trade led to deforestation; much timber was
used in the construction of thousands of ships. There was such concern about the
depletion of the forests thatprotectionlawswerepassedinthe1600s.Rapidly
increasing population of the Industrial Revolution in the 18th and 19th centuries
exacerbated matters creating additional needed fuel and railroad ties. The result
is that less than 1 percent of Great Britain has been continuously forested for more
than four centuries. Much of the bushy landscape now known as “heath” and
“moor” represents the result of human-induced deforestation. Fourth, the United
States was created land wealthy and the forest resource seen as virtually unlimited.
The widespread destruction of the unbroken forests east of the Mississippi River
for agricultural purposes changed both the forest mass and species composition.
The deforestation of landsurface for human needs has had a number of unin-
tended consequences. For instance, wholesale tree removal has rendered large
drainage basins vulnerable to erosion; the deposition of silt at downstream locations
has rendered useless many ports on all the inhabited continents. The biodiversity of
plant and animal life invariably decreases with forest removal as many ecological
niches caused by the presence of the trees no longer exist. The spatial arrangement
of remaining forest patches can be crucial as there are many forest plant and animal
species that do not survive unless there are suitably large expanses of forest canopy.
Just as climate impacts forest cover, forest changes have been shown to drive
some climate changes. Forests provide significant sequestration of the greenhouse92 Deforestation