Trees were mostly found in riparian corridors and along the
foothills and included 14 native species. To understand the role of
the landscape nursery industry in influencing diversity of the tree
canopy cover, we developed three main areas of inquiry. First, we
examined whether there has been a significant change in the number of tree genera and species offered by tree nurseries over time.
Second, we asked whether there have been significant changes in
the functional classifications of trees (natives, non-natives, evergreen, deciduous, angiosperms, gymnosperms, palms) offered over
time. Finally, due to the size of the data set we were curious to know
whether some species had been offered consistently from the early
1900s to 2011