Skip to content
NatureHQ

Study

Positive interactions among alpine plants increase with stress

Callaway, Ragan M.; Brooker, Rob W.; Choler, Philippe; Kikvidze, Zaal; Lortie, Christopher J.; Michalet, Richard

Nature, 2002

Peer-reviewedfield experimentwild

What they did

At mountain sites across several continents, target plants had their neighbours removed while paired targets kept theirs, at both high and low elevation on the same mountains. Survival and growth of the targets were compared, using the same protocol at every site.

Studied in
Plantae
Sample size
paired neighbour-removal plots across mountain sites on several continents

What they found

At high elevation, removing neighbours reduced target plant survival and growth. At lower elevation on the same mountains, removing neighbours improved them. The sign of the interaction reversed with stress.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

Interactions between neighbouring plants shift from competitive to facilitative as physical stress increases.

How NatureHQ reads it

A rare thing: a prediction stated in advance, tested by the same manipulation at many places, and confirmed with the sign of the effect actually reversing. It also demonstrates something the corpus keeps returning to — that whether an interaction helps or harms is not a property of the two species but of the conditions they are in.

Limitations

  • Alpine plants over one or two growing seasons; longer-term outcomes may differ.
  • Elevation bundles several stresses together — cold, wind, exposure — which the design does not separate.

The experiment, explained

  • Pulling out the neighbours, high and low

    Are neighbouring plants competitors or shelter? And does the answer change with how harsh the conditions are?

What this study is used for on NatureHQ

One study can inform several subjects. Here is everywhere this one is cited.

Finding the paper

Published by: Nature PortfolioPublished in a Nature Portfolio journal.

doi.org/10.1038/nature00812

Checked against Crossref on 2026-09-28, and they agree on the title, the authors and the year.

NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-09-04.