Travel Reference
In-Depth Information
When we examine data from a forest it is hard to decide among these and
various other allied hypotheses, the most likely of which also turn out to have
the property of frequency-dependence. My contribution was to fi nd a way to
detect frequency-dependent selection in the data from tropical forests, and
to show that Janzen-Connell, N-C, or some combination of such frequency-
dependent processes really are af ecting many species simultaneously.
Barro Colorado Island and the dynamics of diversity
My work depended on an immense and ongoing project in tropical ecology. In
1979 ecologist Stephen Hubbell, now at UCLA, reported the results of a com-
plete tree census of a 13-hectare dry tropical forest plot in Costa Rica. He found
a complex pattern of scattered and clustered tree species, a pattern that cried
out for more detailed analysis. But the dry forest was cleared for agriculture
soon after he fi nished the study. Frustrated, he resolved never to study a plot
that was in danger of being destroyed. Together with Robin Foster of Chicago's
Field Museum, he proposed a daring idea to the Smithsonian Institution.
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Hubbell and Foster wanted to carry out a complete census of a piece of
tropical rainforest, by determining the species and location of every tree
above a certain size. Then they wanted to come back fi ve years later and see
what has happened to them all. Would they still be there? Would they have
grown, and if so by how much? If they disappeared, which trees replaced
them? Then they wanted to come back in another fi ve years and do the same
thing. The idea was to produce a body of data spanning decades that would
be unprecedented in its scope and detail.
Hubbell and Foster got the OK for this immense project. They picked an
almost completely untouched piece of tropical forest, half a square kilometer
in size, on Barro Colorado Island in Panama's Gatun Lake. There was already
a Smithsonian tropical research center on the island, where students from
all over the world study tropical ecology. And the island, surrounded by the
artifi cial lake that had been fl ooded between 1907 and 1913 to form a major
part of the Panama Canal, was protected from development. They would not
