Hello all, I am gathering data this summer on species abundances beneath 1) plots covered by Ailanthus altissima and 2) plots not covered by Ailanthus. I will have replicate plot data from 4 different sites. I would like to explore the possibility that different species or species types (e.g. vines) may be more abundant under Ailanthus or more likely to be found under Ailanthus. I will have little information about differences between plots and sites aside from Ailanthus presence / absence and light levels. Even then, light levels will probably vary little between plots.
I've been sifting through a variety of information on ordination as it may relate to plant community data. If I understand correctly, some ordination process may be able to tell me if Ailanthus plots cluster together on an ordination axis. Michael Palmer, on his ordination for ecology website, presents a dataset organized by species in rows and "sites" in the columns. This would be one way I might organize my data. My difficulty is in understanding the differences between the many different ordination techniques and how to choose which technique is appropriate for our current task. I look forward to any suggestions from the list. Alan Griffith Department of Biological Sciences University of Mary Washington
