Tree diversity, tree height and environmental harshness in eastern and western North America

Christian O. Marks, Helene C. Muller-Landau, David Tilman, Richard Bardgett

Research output: Contribution to journalLetterpeer-review

46 Scopus citations


Does variation in environmental harshness explain local and regional species diversity gradients? We hypothesise that for a given life form like trees, greater harshness leads to a smaller range of traits that are viable and thereby also to lower species diversity. On the basis of a strong dependence of maximum tree height on site productivity and other measures of site quality, we propose maximum tree height as an inverse measure of environmental harshness for trees. Our results show that tree species richness is strongly positively correlated with maximum tree height across multiple spatial scales in forests of both eastern and western North America. Maximum tree height co-varied with species richness along gradients from benign to harsh environmental conditions, which supports the hypothesis that harshness may be a general mechanism limiting local diversity and explaining diversity gradients within a biogeographic region.

Original languageEnglish (US)
Pages (from-to)743-751
Number of pages9
JournalEcology Letters
Issue number7
StatePublished - Jul 1 2016

Bibliographical note

Publisher Copyright:
© 2016 John Wiley & Sons Ltd/CNRS.


  • Alpha diversity
  • diversity gradients
  • environmental favourability
  • gamma diversity
  • harshness hypothesis
  • maximum tree height
  • site index
  • tree species richness

PubMed: MeSH publication types

  • Journal Article


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