Is the humped relationship between species richness and biomass an artefact due to plot size?

The original article with this name was published in Journal of Ecology 84, 293-295 (1996). Since this article seems to have caused some confusion, I explain here briefly its main points, and comment on some criticism. In this article I suggested that humped species richness against biomass will be produced as an artefact of fixed quadrat size even without any ecological interactions. Hence the name 'no-interactions' model.

First I will briefly explain the assumptions of no-interaction model and how they produce the hump. Then I comment on some misconceptions about the no-interaction model, and tell why I call it an artefact. The key point here is that 'no-interaction' model does not mean that you should not study interactions: On the contrary, instead of circular species richness - biomass observations, you should focus on interactions and on ecologically meaningful parameters. A more technical chapter deals with fitting no-interaction and alternative models. In addition, there is a special analysis of one case that Grime (Journal of Ecoogy. 85, 97-98; 1997) interprets to support his views, and I interpret to support the no-interaction model.

After publishing the article, I have written a simple simulation program for generating vegetation stands. This is a bit more realistic than the original heuristic reasoning in deriving the no-interaction model. The same hump artefact is found even with these more complex and realistic models, but the results give hope to find better ways of describing richness.


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29/4/97