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Predicting species diversity in tropical forests

  • Joshua B. Plotkin
  • Matthew D. Potts
  • Douglas W. Yu
  • Sarayudh Bunyavejchewin
  • Richard Condit
  • Robin Foster
  • Stephen Hubbell
  • James LaFrankie
  • N. Manokaran
  • Lee Hua Seng
  • Raman Sukumar
  • Martin A. Nowak
  • Peter S. Ashton
The National Academy of Sciences
Publication Date
Sep 26, 2000
  • Biology
  • Ecology


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.

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