English Names & other comments
You need to tweak your english names. Silver Maple not Maple Silver for Acer saccharinum, and so-on (River Birch etc), more or less throughout the list. I know your Russian Olive as Oleaster. Tilia cordata is usually known in Europe as Small-leaved Lime. Broadly I would recommend sticking to any national listing for both scientific & vernacular names: these may differ from those on wikipedia, but are likely to be those in other databases & identification literature.
Watch out for cultivars: Corkscrew Willow is Salix matsudana 'Tortosa'. You can use taxon=* or taxon:cultivar=* for either the whole name or just the cultivar name. I'm sure there are others in the list (look for Pendulous, Scarlet, Fastigiate etc in the names): the Choke Cherry is another example, as is Lombardy Poplar (Populus nigra 'Italica'), and the Betula utilis entry.
I'm sceptical that the Weeping Willow is actually Salix babylonica, they are usually Salix × sepulcralis 'Chrysocoma'.
I suspect your Black Walnuts are actually Juglans nigra Black Walnut. As a native tree of the area it seems more likely than an Australian one.
I would recommend using American Plane not American Sycamore for Platanus occidentalis, Pedunculate Oak not English Oak, and Glaucous Willow not Pussy Willow. First avoids the Sycamore/Plane confusion, second avoids a cultural-centric name for a tree which ranges across Europe, last avoids using a name which is widely synonymous.
Change survey:date tag to survey_date_ottawa or similar. survey:date implies not the date of the survey, but what source was used for the (non-existent date tag). I'd stick a suffix in to indicate that this was the date on the open data: OSMers may provide additional information later which I suspect needs a different tag. For instance if a tree is removed and updated on OSM one might want to keep the node to enable reconciliation with newer data releases.
Data collection with handheld GPS devices suggests that, unless they use a secondary reference point dGPS or RTK these will not be massively better than data collected by OSMers
The address data is very useful for cross-checking in OSM. I presume from the write up that you are not planning to import it. Perhaps an explict NOT IMPORTED value in the OSM column would make this clearer. SK53 (talk) 14:54, 30 June 2017 (UTC)