Here are the data that have been recorded from the 1 m x 1m plots to follow the changes over time.  Each line in the spreadsheet refers to data collected in a particular year, plot (plots 1-18), and subplot (the four 1 m x 1 m sampling plots).  The numbers in all the columns refer to the percent cover of a particular plant species in each subplot.  If you scroll to the right, you can see that there are many different plant species that have been found at some location in the experiment.  There are many zeroes in the data because in any one 1 m x 1 m plot, only a subset of all these species are found.  Some plant species are very common though.  For example, the numbers in column M (big bluestem) show that this species is found in nearly all plots (this grass has 3% cover in plot 1B, but 41% cover in plot 1C, for example).