Summary

In this module, we have looked at species richness. We have examined some of the difficulties involved in measuring and characterizing it, and we have spent considerable time looking at some of the explanations for the incredible richness of species found in tropical forests. There is no single explanation for the numbers of species encountered, and the reasons remain hotly contested amongst ecologists.

Understanding how to characterize species diversity at a site is critically important. it may be beended for conservation assessments, but from a management perspective, it is most often needed to assess the impacts of a management intervention on the species present at a site. This where all the subtleties that we have talked about start coming into play. For example the number of species may remain similar, but the composition may change. Rare species may be replaced by common species, yet the overall number of species remains the same. The relative abundance of individuals within species may change, and it is quite common to find that a species is still present in a managed area, but in greatly reduced numbers.

There are many, many questions remaining over the numbers of species found within tropical forests, and why some are rare whereas others are common. We will come back to this question in future modules, and it is likely to remain a topic of major scientific inquiry for the foreseeable future.