Predicting species diversity in tropical forests.
A fundamental question in ecology is how many species occur within a given area. Despite the complexity and diversity of different ecosystems, there exists a surprisingly simple, approximate answer: the number of species is proportional to the size of the area raised to some exponent. The exponent often turns out to be roughly 1/4. This power law can be derived from assumptions about the relative abundances of species or from notions of self-similarity. Here we analyze the largest existing data set of location-mapped species: over one million, individually identified trees from five tropical forests on three continents. Although the power law is a reasonable, zeroth-order approximation of our data, we find consistent deviations from it on all spatial scales. Furthermore, tropical forests are not self-similar at areas </=50 hectares. We develop an extended model of the species-area relationship, which enables us to predict large-scale species diversity from small-scale data samples more accurately than any other available method.
Plotkin
J B
JB
Institute for Advanced Study and Princeton University, Princeton, NJ 08540, USA.
Potts
M D
MD
Yu
D W
DW
Bunyavejchewin
S
S
Condit
R
R
Foster
R
R
Hubbell
S
S
LaFrankie
J
J
Manokaran
N
N
Seng
L H
LH
Sukumar
R
R
Nowak
M A
MA
Ashton
P S
PS