Finally, people are talking on my simplistic level, and I hope I can respond in a meaningful way. I say these things with the definite understanding that they may mark me as just an old, irrelevant fart in today's exciting world.
It seems to me that ecosystems do two things, and that both are outlined in Ecology 101 and the texts used for that course. First, they collect and process energy (one ecosystem function is energy flow). Second, they move materials through ecosystem compartments (a second ecosystem function is biogeochemical cycling). Each of these two functions drives and modulates the other. That does not mean that the other things that people are interested in, and sometimes speak of as ecosystem functions are not important, and should not be considered. Those things can also contribute to understanding ecosystems in greater depth and more accurately. The things mentioned by others on here are certainly important. But the function of an entity is, to me, simply what it does. What ecosystems do is process energy and matter, in the general ways I have described above. Certainly many of the things we are interested in, things like carbon balance and heat accumulation, natural resource use and protection, agriculture are dependent on what ecosystems do -- process energy and matter. To speak of the other things that have been discussed as the functions of ecosystems would be akin to saying that the function of the pancreas is to prevent diabetes. The function of the pancreas is to secrete hormones and digestive enzymes. The part about diabetes relates more to its integration with the body of which it is a part. I hope this is of some use. Just thought a reminder of fundamentals might be appropriate. David McNeely ---- Martin Meiss <[email protected]> wrote: > Nicolas, > Why would you restrict your interest to the flow of energy, and not > include the flow of material, such as a nutrient like fixed nitrogen, or > potassium? > > Martin M. Meiss > > 2012/9/27 Katharine Miller <[email protected]> > > > Hi, > > > > I wanted to thank everyone for their responses and recommendations. Some > > of > > them were quite helpful and have got me thinking in new ways. > > > > With respect to the use of the Rao index, I didn't express my question very > > well. What I was really trying to discern was whether it was appropriate to > > use the Rao index values as a distance matrix of functional dissimilarity > > between estuaries that could then be evaluated using standard multivariate > > methods (i.e. clustering). I have not seen Shannon entropy used this way > > either, but it is understood that pairwise beta diversity calculated by > > either of these approaches is a measure of dissimilarity between sites. So, > > on that basis, it doesn't seem too much of a stretch. Also, the index > > values > > are used as dissimilarities in Mantel tests or other matrix calculations. > > > > I am not sure whether the reason these indices have not been used this way > > is because it would be inappropriate statistically or mathematically, or > > whether there is some ecological reason for not doing it. > > > > Thanks again. > > > > - Katharine > > > > > > -- David McNeely
