The tropical forests of Borneo and Amazonia may each contain more tree species diversity in half a square kilometre than do all the temperate forests of Europe, North America, and Asia combined1. Biologists have long been fascinated by this disparity, using it to investigate potential drivers of biodiversity2. Latitudinal variation in many of these drivers is expected to create geographic differences in ecological2,3,4 and evolutionary processes4,5, and evidence increasingly shows that tropical ecosystems have higher rates of diversification, clade origination, and clade dispersal5,6. However, there is currently no evidence to link gradients in ecological processes within communities at a local scale directly to the geographic gradient in biodiversity. Here, we show geographic variation in the storage effect, an ecological mechanism that reduces the potential for competitive exclusion more strongly in the tropics than it does in temperate and boreal zones, decreasing the ratio of interspecific-to-intraspecific competition by 0.25% for each degree of latitude that an ecosystem is located closer to the Equator. Additionally, we find evidence that latitudinal variation in climate underpins these differences; longer growing seasons in the tropics reduce constraints on the seasonal timing of reproduction, permitting lower recruitment synchrony between species and thereby enhancing niche partitioning through the storage effect. Our results demonstrate that the strength of the storage effect, and therefore its impact on diversity within communities, varies latitudinally in association with climate. This finding highlights the importance of biotic interactions in shaping geographic diversity patterns, and emphasizes the need to understand the mechanisms underpinning ecological processes in greater detail than has previously been appreciated.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1.

    Plant diversity in tropical forests: a review of mechanisms of species coexistence. Oecologia 130, 1–14 (2002)

  2. 2.

    Geographical Ecology: Patterns in the Distribution of Species (Princeton Univ. Press, 1984)

  3. 3.

    On the causes of gradients in tropical tree diversity. J. Ecol. 87, 193–210 (1999)

  4. 4.

    Latitudinal gradients in species diversity: a review of concepts. Am. Nat. 100, 33–46 (1966)

  5. 5.

    , , , & Is there a latitudinal gradient in the importance of biotic interactions? Annu. Rev. Ecol. Evol. Syst. 40, 245–269 (2009)

  6. 6.

    , & Out of the tropics: evolutionary dynamics of the latitudinal diversity gradient. Science 314, 102–106 (2006)

  7. 7.

    et al. Evolution and the latitudinal diversity gradient: speciation, extinction and biogeography. Ecol. Lett. 10, 315–331 (2007)

  8. 8.

    , , & Asymmetric density dependence shapes species abundances in a tropical tree community. Science 329, 330–332 (2010)

  9. 9.

    Herbivores and the number of tree species in tropical forests. Am. Nat. 104, 501–528 (1970)

  10. 10.

    Diversity in tropical rain forests and coral reefs. Science 199, 1302–1310 (1978)

  11. 11.

    et al. Negative plant–soil feedback predicts tree-species relative abundance in a tropical forest. Nature 466, 752–755 (2010)

  12. 12.

    & Effects of above- and belowground competition on growth and survival of rain forest tree seedlings. Ecology 81, 2525–2538 (2000)

  13. 13.

    Competition and biodiversity in spatially structured habitats. Ecology 75, 2–16 (1994)

  14. 14.

    , & Spatial dynamics in model plant communities: what do we really know? Am. Nat. 162, 135–148 (2003)

  15. 15.

    The tolerance-fecundity trade-off and the maintenance of diversity in seed size. Proc. Natl Acad. Sci. USA 107, 4242–4247 (2010)

  16. 16.

    & Life history diversity of canopy and emergent trees in a neotropical rain forest. Ecol. Monogr. 62, 315–344 (1992)

  17. 17.

    , & Comparative analysis of microhabitat utilization by saplings of nine tree species in neotropical rain forest. Biotropica 25, 397–407 (1993)

  18. 18.

    Mechanisms of maintenance of species diversity. Annu. Rev. Ecol. Syst. 31, 343–366 (2000)

  19. 19.

    , & Density-dependent mortality and the latitudinal gradient in species diversity. Nature 417, 732–735 (2002)

  20. 20.

    , , , & Assessing the evidence for latitudinal gradients in plant defence and herbivory. Funct. Ecol. 25, 380–388 (2011)

  21. 21.

    et al. Testing predictions of the Janzen–Connell hypothesis: a meta-analysis of experimental evidence for distance- and density-dependent seed and seedling survival. J. Ecol. 102, 845–856 (2014)

  22. 22.

    , & Coexistence in tropical forests through asynchronous variation in annual seed production. Ecology 93, 2073–2084 (2012)

  23. 23.

    , & The phenology of tropical forests: adaptive significance and consequences for primary consumers. Annu. Rev. Ecol. Syst. 24, 353–377 (1993)

  24. 24.

    & Seasonal, El Niño and longer term changes in flower and seed production in a moist tropical forest. Ecol. Lett. 9, 35–44 (2006)

  25. 25.

    , , & in Biodiversity and Ecosystem Function (eds & ) 433–451 (Springer, 1994)

  26. 26.

    Synchrony of regeneration, gaps, and latitudinal differences in tree species diversity. Ecology 70, 546–547 (1989)

  27. 27.

    et al. Predictions and tests of climate-based hypotheses of broad-scale variation in taxonomic richness. Ecol. Lett. 7, 1121–1134 (2004)

  28. 28.

    , & A niche for neutrality. Ecol. Lett. 10, 95–104 (2007)

  29. 29.

    General flowering in lowland mixed dipterocarp forests of South-east Asia. Biol. J. Linn. Soc. 75, 233–247 (2002)

  30. 30.

    . & . (eds) Tropical Forest Diversity and Dynamism: Findings from a Large-Scale Plot Network (Univ. Chicago Press, 2004)

  31. 31.

    et al. Community structure of a species-rich temperate forest, Ogawa Forest Reserve, central Japan. Vegetatio 98, 97–111 (1992)

  32. 32.

    , , & Annual and spatial variation in seedfall and seedling recruitment in a neotropical forest. Ecology 86, 848–860 (2008)

  33. 33.

    ., . & A Systems Analysis of the Global Boreal Forest (Cambridge Univ. Press, 1992)

  34. 34.

    & Environmental variability promotes coexistence in lottery competitive systems. Am. Nat. 117, 923–943 (1981)

  35. 35.

    Tropical Nature, and Other Essays (Macmillan and Company, 1878)

  36. 36.

    Tree species richness of upper Amazonian forests. Proc. Natl Acad. Sci. USA 85, 156–159 (1988)

Download references


We thank J. M. Levine, M. G. Turner, D. M. Waller, D. J. Mladenoff and J. Zhu for comments on the manuscript, and S.-H. Wu of the Taiwan Forestry Research Institute for plant identification. We acknowledge the following funding sources, which have been essential in the ongoing collection of long-term forest data (in alphabetical order): Andrew M. Mellon Foundation, Center for Tropical Forest Science, Environment Research and Technology Development Fund of the Japan Ministry of the Environment, JSPS KAKENHI, National Key Research and Development Program of China, National Natural Science Foundation of China, National Science Foundation of the United States (DDIG, IGERT, LTER, LTREB), Natural Environment Research Council of the UK, Natural History Museum of London, Smithsonian Tropical Research Institute, Taiwan Forestry Bureau, Taiwan Forestry Research Institute, Taiwan Ministry of Science and Technology, USDA Forest Service.

Author information


  1. Department of Integrative Biology, University of Wisconsin, Madison, Wisconsin, USA

    • Jacob Usinowicz
    •  & Anthony R. Ives
  2. Department of Natural Resources and Environmental Studies, National Dong Hwa University, Hualien, Taiwan

    • Chia-Hao Chang-Yang
    • , Yu-Yun Chen
    •  & I-Fang Sun
  3. Nicholas School of the Environment, Duke University, Durham, North Carolina, USA

    • James S. Clark
  4. Forest Research Institute Malaysia, Kuala Lumpur, Malaysia

    • Christine Fletcher
  5. Department of Plant Biology, Southern Illinois University, Carbondale, Illinois, USA

    • Nancy C. Garwood
  6. Institute of CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China

    • Zhanqing Hao
    •  & Yunyun Wang
  7. Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska, USA

    • Jill Johnstone
  8. Department of Life Science, Tunghai University, Taichung, Taiwan

    • Yiching Lin
  9. Biology Department, Lewis & Clark College, Portland, Oregon, USA

    • Margaret R. Metz
  10. Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan

    • Takashi Masaki
  11. Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan

    • Tohru Nakashizuka
  12. Research Institute for Humanity and Nature, Kyoto, Japan

    • Tohru Nakashizuka
  13. Laboratorio de Ecología de Plantas, Herbario QCA, Pontificia Universidad Católica del Ecuador, Quito, Ecuador

    • Renato Valencia
  14. Department of Environmental Science, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico

    • Jess K. Zimmerman
    •  & S. Joseph Wright
  15. Smithsonian Tropical Research Institute, Apartado 0843–03092, Balboa, Panama

    • S. Joseph Wright


  1. Search for Jacob Usinowicz in:

  2. Search for Chia-Hao Chang-Yang in:

  3. Search for Yu-Yun Chen in:

  4. Search for James S. Clark in:

  5. Search for Christine Fletcher in:

  6. Search for Nancy C. Garwood in:

  7. Search for Zhanqing Hao in:

  8. Search for Jill Johnstone in:

  9. Search for Yiching Lin in:

  10. Search for Margaret R. Metz in:

  11. Search for Takashi Masaki in:

  12. Search for Tohru Nakashizuka in:

  13. Search for I-Fang Sun in:

  14. Search for Renato Valencia in:

  15. Search for Yunyun Wang in:

  16. Search for Jess K. Zimmerman in:

  17. Search for Anthony R. Ives in:

  18. Search for S. Joseph Wright in:


J.U. analysed data and wrote the paper. C.-H.C.–Y., Y.-Y.C., J.S.C., C.F., N.C.G., Z.H., J.J., Y.L., M.R.M., T.M., T.N., I.S., R.V., Y.W., J.K.Z., and S.J.W. have established, maintained, and collected data from long-term demography plots. S.J.W. and A.R.I. contributed equally to paper conception and development. All authors discussed results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Jacob Usinowicz.

Reviewer Information Nature thanks R. Bagchi, S. McMahon, G. Mittelbach and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Supplementary information

About this article

Publication history






Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.