One of the challenges and beauty of ecology is the fact that the work is done within relatively complex environment, where a lot of factors are working together to create the observation we are interested in. therefore, ecologists find themselves in a constant demand for generalizations and theory, which will help them simplified nature.
As part of this effort, many indices were proposed whose goal is to measure biotic interactions and translate them into scales and units which can be compared among studies. One of the relevant distinction is that the strength of biotic interactions (positive or negative) can be measured in two different ways: we can talk about interactions’ intensity, in which case we compare the performance of our target organisms with and without neighbors within a certain environment, or we can talk about importance of the interactions, in which case we take into account not only the performance of the organism within a certain environment, but also its contribution relative to other environmental factors in the system.  The distinction is particularly relevant when studying organism performance along environmental factors.
Check out what we proposed to do:
  • Seifan M., Seifan T., Ariza C., K. Tielbörger. 2010. Facilitating an importance index. Journal of Ecology 98: 356-361. (

And the discussion:

  • Seifan T., and M. Seifan. 2015. Symmetry and range limits in importance indices. Ecology & Evolution doi: 10.1002/ece3.1649.
  • Brooker R., Kikvidze Z., Kunstler G., Liancourt P., M. Seifan. 2013. The concept and measurement of importance: a comment on Rees et al. 2012. Journal of Ecology 101: 1369-1378. (, M., Childs, D.A., R.P.