Letter | Published:

Positive interactions among alpine plants increase with stress

Abstract

Plants can have positive effects on each other1. For example, the accumulation of nutrients, provision of shade, amelioration of disturbance, or protection from herbivores by some species can enhance the performance of neighbouring species. Thus the notion that the distributions and abundances of plant species are independent of other species may be inadequate as a theoretical underpinning for understanding species coexistence and diversity2. But there have been no large-scale experiments designed to examine the generality of positive interactions in plant communities and their importance relative to competition. Here we show that the biomass, growth and reproduction of alpine plant species are higher when other plants are nearby. In an experiment conducted in subalpine and alpine plant communities with 115 species in 11 different mountain ranges, we find that competition generally, but not exclusively, dominates interactions at lower elevations where conditions are less physically stressful. In contrast, at high elevations where abiotic stress is high the interactions among plants are predominantly positive. Furthermore, across all high and low sites positive interactions are more important at sites with low temperatures in the early summer, but competition prevails at warmer sites.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1

    Callaway, R. M. Positive interactions among plants. Bot. Rev. 61, 306–349 (1995)

  2. 2

    Callaway, R. M. Positive interactions in plant communities and the individualistic-continuum concept. Oecologia 112, 143–149 (1997)

  3. 3

    Berlow, E. L. Strong effects of weak interactions in ecological communities. Nature 398, 330–334 (1999)

  4. 4

    Miller, T. E. Direct and indirect species interactions in an early old-field plant community. Am. Nat. 143, 1007–1025 (1994)

  5. 5

    Grime, J. P. Evidence for the existence of three primary strategies in plants and its relevance to ecological and evolutionary theory. Am. Nat. 111, 1169–1194 (1977)

  6. 6

    Connell, J. H. On the prevalence and relative importance of interspecific competition: evidence from field experiments. Am. Nat. 122, 661–696 (1983)

  7. 7

    Pugnaire, F. I. & Luque, M. T. Changes in plant interactions along a gradient of environmental stress. Oikos 93, 42–49 (2000)

  8. 8

    Brooker, R. W. & Callaghan, T. V. The balance between positive and negative plant interactions and its relationship to environmental gradients: a model. Oikos 81, 196–207 (1998)

  9. 9

    Bertness, M. D. & Callaway, R. M. Positive interactions in communities. Trends Ecol. Evol. 9, 191–193 (1995)

  10. 10

    Markham, J. H. & Chanway, C. P. Measuring plant neighbor effects. Funct. Ecol. 10, 548–549 (1996)

  11. 11

    Grime, J. P. Plant Strategies and Vegetation Processes (Wiley, Chichester, 1979)

  12. 12

    Dodds, W. K. Interspecific interactions: constructing a general neutral model for interaction type. Oikos 78, 377–383 (1997)

  13. 13

    Woodward, F. I., Smith, T. M. & Emanuel, W. R. A global primary productivity and phytogeography model. Glob. Biogeochem. Cycles 9, 471–490 (1995)

  14. 14

    Shaver, G. R. & Jonasson, S. Response of arctic ecosystems to climate change: result of long-term field experiments in Sweden and Alaska. Polar Res. 18, 245–256 (1999)

  15. 15

    Prentice, C. I. et al. A global biome model based on plant physiology and dominance, soil properties, and climate. J. Biogeogr. 19, 117–134 (1992)

  16. 16

    Gleason, H. A. The individualist concept of the plant association. Bull. Torrey Bot. Club 53, 7–27 (1926)

  17. 17

    Whittaker, R. H. Communities and Ecosystems (Macmillan, New York, 1975)

  18. 18

    Begon, M., Harper, J. L. & Townsend, C. R. Ecology 2nd edn 626–628 (Blackwell, London, 1990)

  19. 19

    Johnson, H. B. & Mayeux, H. S. Viewpoint: a view on species additions and deletions and the balance of nature. J. Range Manag. 45, 322–333 (1992)

  20. 20

    Curtis, J. T. The Vegetation of Wisconsin (Univ. Wisconsin Press, Madison, 1959)

  21. 21

    Whittaker, R. H. A consideration of climax theory: the climax as population and pattern. Ecol. Monogr. 23, 41–78 (1953)

  22. 22

    Austin, M. P. Continuum concept, ordination methods, and niche theory. Annu. Rev. Ecol. Syst. 16, 39–61 (1985)

  23. 23

    Callaway, R. M. Are positive interactions species-specific? Oikos 82, 202–209 (1998)

  24. 24

    Choler, P., Michalet, R. & Callaway, R. M. Facilitation and competition on gradients in alpine plant communities. Ecology 82, 3295–3308 (2001)

  25. 25

    Archibold, O. W. Ecology of World Vegetation 280–318 (Chapman and Hall, London, 1995)

  26. 26

    JMPin 4.0.2 (SAS Institute Inc., Duxbury Press, Cary, North Carolina, 2000)

Download references

Acknowledgements

We thank the National Center for Ecological Synthesis and Analysis, The National Geographic Society, the Civilian Research and Development Foundation, and the Andrew W. Mellon Foundation for financial support.

Author information

Competing interests

The authors declare that they have no competing financial interests.

Correspondence to Ragan M. Callaway.

Supplementary information

  1. Appendix 1 (DOC 328 kb)

  2. Supplementary information and references (DOC 19 kb)

Rights and permissions

Reprints and Permissions

About this article

Further reading

Figure 1: Relative neighbour effect (RNE) at the 11 experimental sites.
Figure 2: Proportion of surviving target species in controls and neighbour removal treatments at high and low elevation experimental sites for all 11 locations combined.
Figure 3: Proportion of flowering or fruiting target species in controls and neighbour removal treatments at high and low elevation experimental sites for all 11 locations combined.
Figure 4: The relationship between relative neighbour effect (RNE) and the estimated maximum temperature in early summer (June in the Northern Hemisphere and December in the Southern Hemisphere) at each of the 22 experimental sites.

Comments

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.