Dr. Ed Gilman of the University of Florida has created several cue cards to help you out in the field including Selection and grading (pdf), Planting (pdf), Pruning at planting (pdf), Pruning young trees (pdf), Pruning methods (pdf), Restoration pruning (pdf), Root management (pdf)
The Alliance for Community Trees, (ACT) and USFS Conservation Planning for Growth and Open Space Conservation have excellent webcast archives; both have explored great topics in the recent past.
Looking to learn? Check out Len Phillips’ “Online Seminars for Municipal Arborists”
It’s difficult, if not impossible, to know what goes on inside a tree, but Tree Decay, An Expanded Concept, published by the US Forest Service, gives us a great virtual tour.
When you think about biodiversity, don’t forget about the Hidden World Under Our Feet