It's really great to see people working on regionally appropriate landscapes, and some of these pictures are really beautiful.
Just a couple of thoughts:
* The appearance of a specific species of tree can change dramatically depending on where the tree is. Isolated trees will spread out to take advantage of their open view of the sky, while trees in a stand will tend to grow upwards to compete with other trees. A tree on a windswept crag may be twisted and stunted compared to another tree of the same species in a different environment.
* As best as I can recall, naturally-growing palms are quite rare in Europe and North Africa. They will usually occur in places where they have been deliberately planted -- ie, in orchards or groves.
* Stone bridges, as beautiful as they may be, were also quite rare -- at least over major rivers. The building of an arched stone bridge was a major event which required massive expenditures, but which could transform the trade routes in a particular region. A bridge of lashed-together boats, or more likely a ferry or a ford, would be much more common in isolated areas for really significant river. You might find stone bridges over smaller rivers along former Roman roads or other major axes of transportation, although again I suspect that a ford would be much more common.
* Even in the 13th century, a lot of Europe was still wetland: coastal salt marshes, inland bogs, fens, etc.