Savannah and Grassland

Harry Erwin (
Thu, 12 Oct 1995 21:37:31 -0400

Professor Lee Talbot spoke today in ecology class about succession
processes. As an aside, he noted that H. sapiens is a keystone species for
tropical savannah and temperate grassland. Grass species turn out to be an
early successional group in those environments, with the later groups
being woody bush and tree species. The maintenance of temperate grassland
and tropical savannah depends on the presence of fire to keep the woody
species from taking over. Homo is the keystone because the alternative
source of fire (lightning- caused) is rare in temperate grassland and
unknown in tropical savannah.

Reference: LM Talbot (1989) "Man's Role in Managing the Global
Environment," in Changing the Global Environment, Academic Press, 18-20.

This blew me away. Talbot is a well-known expert on the Serengeti
ecosystem. He quite simply believes that H. erectus used fire from the
beginning to create the savannah he lived in. He believes this has been
going on for at least 2 MYr and perhaps 3 MYr. The implications if he is
correct are far-ranging. For example, the ancestor of whatever hominid
species first ventured out on the open savannah had to have fire and was
using it habitually to keep his environment cleared.

When does the pollen data show the emergence of widespread tropical and
temperate grasslands?

Other comments?

Harry Erwin
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PhD student in comp neurosci: "Glitches happen" & "Meaning is emotional"