Trees- update

Alex Johnson, who is the Urban Forestry Manager for the City of Durham, has taken the time to respond to some of the issues Josh raised in his email to the Ellerbe Creek Watershed Association, excerpted below. I'm reprinting Alex's response below. I think the dialog being established in this case is good for the city, its residents, and the future streetscape of our urban neighborhoods. There's a lot of expertise aroudn here. Making sure it's all utilized is in everyone's best interests.

You may have read the article in the N&O about Durham’s dying trees. You may have also seen Josh Rose’s plea to plant natives under powerlines and forego the exotics.

Please let me share my perspective as Urban Forestry Manager for Durham.

First; Replacement trees for ‘07/08 (Natives outnumber exotics):

Overcup oak (native) Ginkgo (exotic)
Live oak (native) Lacebark elm (exotic)
Willow oak (native) Trident maple (exotic)
American elm (native) Chinese pistache (exotic)
Red maple (native) crepe myrtle (exotic)
Sugar maple (native) Japanese dogwood (exotic)
American elm (native) Japanese snowbell (exotic)
Yellowwood (native) Chinese redbud (exotic)
Oklahoma redbud (native)
Snowdrop tree (native)


Second; Many native species are not available locally in the quantity, size, or quality required.

Third; No causal link’s been established between the introduction of Japanese dogwood and the appearance of dogwood anthracnose.

Finally; Although I prefer natives, they do best in undisturbed conditions. Most are very sensitive to soil chemistry, hydrology, compaction, pollution, heat, and other urban stressors, more so than particular exotics. This is particularly true with the understory trees suitable for planting under powerlines.

If your planting space consists of a 3’ gap between the curb and the sidewalk filled with the typical clay backfill of urban sites, Crepe myrtle is simply your best choice.

Even the tougher natives like smoketree and fringetree don’t lend themselves to being planted in narrow strips because they don’t grow into perfect lollypops with clear trunks under green canopies; this is what we are required to have in that streetside strip to allow motorists and police officers a clear view around and through the trees.

With the restrictions on what I can plant due to the challenging nature of urban planting sites, the scarcity of natives in the nursery trade, and the need to accommodate internal restrictions, I need to have a broad a pallet of trees to draw upon. This pallet is going to inevitably contain exotic species. To expect or demand anything else is understandable, but doesn’t take into account the complexity of the issue.

I've pointed out to Alex a particular planting in my neighborhood where several willow oaks were taken down and replaced with crepe myrtle, where narrow right of way, sidewalks, etc. were not an issue. It may be that the neighbors asked for these trees, or it may simply be a case where that was what was on hand. Hopefully, out of this conversation will emerge a policy where the right tree is matched to the right location, rather than the easiest or most convenient planting.