There is an interesting story about Elm tree replacement in Harvard Yard. It discusses choice of trees, diseases, spacing, etc.
Visalia CA Beautification Committee has provided references on planting trees, not topping them, and their oak tree ordinance.
Santa Margarita Community Forestry is a member of an alliance of community-based tree groups promoting citizen action and environmental stewardship through planting and caring for trees.
Longwood Gardens PA. A premier horticultural display garden of 1,050 acres was created by industrialist Pierre S. du Pont.
American Forests is a great site full of information about trees. It has a climate calculator to determine carbon levels from various pollution sources, which you enter in a form, it then calculates how many trees are needed to mitigate those sources.
National Tree Trust programs designed for volunteer participation in order to reach the goals of the "America the Beautiful Act of 1990." Includes Growing Together: for pre-kindergarten through 6th-grade school children, Trail of Trees which focuses on the value of trees in our neighborhoods and our economy, Community Tree Planting which revitalizes rural and urban communities tree-planting efforts on public lands and on roadsides, and their Partnership Enhancement Program which provides monetary grants to local tree-planting organizations that support volunteer tree-planting and education efforts.
A family's Backyard Forest in FAIRFIELD, OHIO They started with wildflowers, but soon graduated to prairie grasses and then to trees and shrubs.
Society of Municipal promotes and improves the practice of professional municipal arboriculture and stimulates greater interest in the planting and presentation of shade trees and landscape plants.
Urban Tree Book describes the trees of city and town neighborhoods, the trees that people live with every day. It identifies some 200 species to be discovered and enjoyed in urban walks and explorations. Includes new information on the Asian Long-horned Beetle
The USDA Forest Service St. Paul Field Office provides a guide on how to prune trees and other help on on forest health and tree care, natural resources management, and other forestry related topics.
Here is a database to help select proper trees for different conditions. It is intended for California but most of their information applies here as well. The site has over 4000 photos and will convert common names into scientific ones and also the reverse.
This Lexington Kentucky site deals with the natural history of trees. It is in database format and includes information about the identification, ecology, life history, distribution and use of trees. Not quite finished, it has about 150 complete descriptions and they plan to do about 1000.