Summertime

Yeah, it's hot and humid already.

But the linden trees are blooming. There's a pair on Main St., between Bull McCabe's and Five Points. Walk beneath and take a deep breath.

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Trees

Last year, there was a big brouhaha over the poor pruning practices of our city's large urban trees, mostly raised in Watts Hospital-Hillandale and Trinity Park neighborhoods. Kevin wrote about it here. (I also touched on the issue here and here.)

The solution, or compromise, that was reached called for Duke Energy to meet with neighborhood associations before pruning, and also to enlist city arborists to hep determine which trees needed pruning, and how much pruning to do.

This morning an alarmed email appeared on my neighborhood list serve indicating that Duke Energy folks had been speaking individually to neighbors letting them know their tree trimming crews would be at work on their blocks in the very near future. I know for certain that no meeting with our association has taken place. And i strongly suspect that Duke Energy is not consulting with the city on this project. Maybe they thought the whole matter had blown over?

Regardless, there's lots of discussion going on right now. Here's the latest from the city's department of urban forestry.

I read your posting to the Duke Park list-serve this morning and I thought it deserved a reply. Let me first say that your observations are correct and your anger and indignation is justified. It is not my place to explain or defend the practices of Townsend Tree Care in their pursuit of fulfilling their contract with Duke Energy, but I feel it is my job to inform the public on why the situation has gotten to where it is and what can be done about it.

The major component of Durham’s streetscape consists of willow and water oak trees planted in the period roughly between the mid 1930’s through the 1950’s. For a long time the trees and powerlines have coexisted due to constant pruning work done at Duke Power’s expense. The early pruning practices called for “rounding over” the trees, like you would do to a boxwood, to create trees that look like mushrooms.

This practice was phased out in the 1980’s when the science of Arboriculture took a giant leap in its applied understanding of tree physiology under the lead of Dr. Alex Shigo. It was shown that “rounding over” is not sustainable and leads to trees that are dangerous to the public when the decay resulting from numerous treatments finally undermines the trees’ structure.

The shift to “directional pruning” that took place in the 1980’s created the Y-shaped trees that we now have. It was instituted by a crew of tree workers who were “dedicated” to Durham. They worked year-round and constantly pruned trees from one side of town to the next. The “pruning cycle” that was thus established meant that trees received maintenance roughly every 2-4 years.

Somewhere in the late 1990’s Duke Power became Duke Energy and expanded it’s share of the market. It absorbed competitors and moved its operations base to Charlotte. In the process it stopped its
dedicated Durham crew and went away from a pruning cycle and adopted an “on demand” policy. In other words, trees no longer obtained systematic pruning to keep the power on, they waited until the "reliability” of the circuit became compromised (power was interrupted by contact with tree limbs) to act. When they acted, they did so in such a way as to remove all of the growth that had accrued since the last pruning cycle (~8-10 years) and to further prune in an attempt to guarantee that the tree wouldn’t interfere with the line for 8-10 years. This is what their contract with Townsend stipulates – 15’ of learance from the wires with no overhanging branches.

What I am confronted with today are trees that are in overall pretty poor shape due to their age (these trees can be expected to live another 5-20 years depending on the site and when they were planted), their history of pruning, incidents of drought and vehicle impacts (both the pollution and being physically hit). This is the backdrop into which we now introduce the contractors who have been given an impossible task; to make powerlines “tree-proof” for a period of 8-10 years after up to a decade of deferred maintenance (and still perform their function as street trees). In many cases, it couldn’t be done. The work required by Duke Energy would leave trees that look more like goalposts or totem poles; “trees” in name only whose liability for potential failure would outweigh any potential benefit they could deliver. Rather than have the power company leave me with more dangerous tree for my already overextended crew to deal with, I’ve directed a lot of removals.

I approach this problem knowing that the power company has the right to maintain its lines, and the way in which it does so needs to translate across all of its jurisdictions (not all towns and citys in D.E.’s customer base are as full of oaks planted under powerlines as Durham). My “solution” is to push for a compromise, to go back to a pruning cycle (4-5 years instead of 8-10) and to replace large trees under the lines with small-medium ones. The cycle issue is being addressed through a “master permit” process as well as internal dialogue with D.E. representatives. The tree replacement part will need to be addressed through the Street Tree Replacement Partnership program, which requires neighborhoods to take a proactive role in replacing the trees in the right of way next to their homes and businesses. This link goes to the city’s website that explains the program and I’d encourage you and your neighbors to participate:
http://www.durhamnc.gov/departments/general/forestry.cfm I am available to speak to groups of people who are interested in coordinating their efforts to get trees replaced and would be happy to set something up for Duke Park.

Feel free to post this on the list-serve and/or contact me personally.

Alex Johnson RF, CA
Urban Forestry Manager
City of Durham General Services Department
Office: 560-4197 Extension 275

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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.

Continue reading Trees- update

Trees

There was a lot of talk in the local blogosphere a month or two back about the piss-poor job being done pruning Durham's beautiful willow oaks by a contractor hired by Duke Energy. (See here, and here, for example, as well as this news story.)

Turns out that's not the only problem with the willow oaks. Seems they were all planted at around the same time in the 1930s, and they're all reaching the end of their lifespans around the same time. (Gary indicates that they're only middle aged, but i think that even without the pruning, the stress of being planted in streetside right-of-ways has got to cut quite a bit off the useful life of a tree.) As i recall, the entire block across the street from Club Blvd. Elementary had its willow oaks removed in the late 90s as they were deemed to unhealthy and dangerous to leave standing.

Josh Rose, a biologist and former Old North Durham resident who lives now in Texas but still stays in touch, doesn't dispute that a lot of these trees are going to need replacing. But he sees some problems with the approach which Durham officials are quoted as presenting.

About the Willow Oak replacement discussed in the article, it
is disturbing to see that nearly all of the proposed smaller replacement trees, the ones for areas with powerlines (which covers a lot of Durham streets), are non-native. Trident Maple, Hedge Maple, Paperbark Maple, and Crepe Myrtle are all native to Asia. You might think that we would have learned to quit planting non-native trees in the US after we introduced Dutch Elm Disease and Chestnut Blight and wiped out what had been two dominant trees from eastern US forests and neighborhoods, but apparently not, so now we have Dogwood Anthracnose, Hemlock Wooly Adelgid, Oak Wasting Disease, Emerald Ash Borer...

The other issue with non-native trees is insect diversity. Native trees, including the Willow Oaks, have leaves edible to numerous caterpillars, beetles, and other insects. Native flowering trees, like redbuds and dogwoods, attract all sorts of pollinators like butterflies, bees, flies, and more. Not only do the butterflies themselves lend color to the neighborhood, but the other, less visible insects are food for songbirds like warblers, vireos, flycatchers, chickadees, nuthatches, and many others. You will very rarely see birds like these in a Crepe Myrtle or other non-native, because there is virtually nothing for them to eat. You might see the occasional mockingbird or cardinal there, not much else.

Seems like it shouldn't be that much harder to make smart decisions regarding our next generation of tree plantings, rather than short-sighted ones. Josh continues:

Anyone in Old North Durham, Watts-Hillandale, or other neighborhoods (and this includes virtually all of Durham's urban neighborhoods, including Trinity Park, Old West Durham, Northgate Park, Duke Park, Cleveland-Holloway, et al) with aging trees needing replacement, if you would like to see as many or more birds and butterflies around your yards, convince your city to plant only tree species native to the US. Note that even some commonly used dogwoods and redbuds are Asian (hence the Dogwood Anthracnose, a fungus carried by Asian dogwoods that threatens our native species), so make sure to specifically ask for Cornus florida and Cercis canadensis. Some other natives, probably not carried by
the city arborists, but available from some local nurseries, and which tend to stay small enough to not threaten powerlines, include Fringe-tree (Chionanthus virginicus), Parsley Hawthorn (Crataegus marshallii), Persimmon (Diospyros virginiana), Sourwood (Oxydendrum arboreum), Fevertree (Pinckeya bracteata), and various species of Buckeye (Aesculus spp.). I'm sure there are others. Of course, in areas without powerlines, the possibilities are nearly endless, including Beech, Tulip Poplar, Sycamore, Red Cedar, various Birches, and many more...

(Neighborhoods listed in italics added to Josh's letter.)

All of my experiences with Durham's Department of Urban forestry have been overwhelmingly positive, and i can't imagine that the smart and dedicated people there haven't thought this through. But still, it wouldn't hurt to drop them a line and ask them to consider a program of replacing these willow oaks with native trees for the reasons Josh mentions. We'd like Durham to be even more livable for those who will be here long after we're gone.

Continue reading Trees