Somehow I came across this resource - what a find: Glebe Trees. It helps identify the trees along each street and also provides a spring log that was created in 2009 documenting the changes in the trees from March until the end of April. You can peruse a nice long list of all the species of trees found in the Glebe and it even has an identification key using size, flowers, leaves, bark, form and season. Brilliant!
It also provides a link to the Environment Committee of the Glebe Community Association which was running a project to document the health of Glebe trees with the help of volunteers called "Re-TREE Our Glebe":
The project to inventory trees on City rights-of-way led by Carol MacLeod was stymied by technical data entry problems in 2010, but is hoping to continue the project in 2011. Volunteers are always needed.
Not sure if the project is still ongoing.
What about planting more native trees as per Diana Beresford-Kroeger?