A rare opportunity

This weekend I was lucky enough to be included in a project to prune the Treaty Oak, organized by the Texas Chapter of the ISA and Austin PARD. Our team in the tree was myself, Nevic Donnelly, Guy LeBlanc, and Keith Brown. There was a fifth climber who works for the City, but I'm sorry to say I did not get his name. We had ground support from two more City PARD employees, PARD Forestry Director Walter Passmore, and Don Gardner. It was a cold, blustery day, but I dressed for it and didn't suffer much. Walter set some high bars to climbers who wanted to take part: several years of ISA Certification and climbing experience, and/or experience climbing the tree in the past (I don't remember all the details, but there weren't all that many arborists in town who qualified).

I qualified on both counts, since this was the second time I climbed this tree. I was working for another company who pruned it several years ago, maybe 1996. I'm pleased to say the tree seems to have improved in health since then. A funny thing about Live Oaks (Q. fusiformis) is that they tend to get very brittle when stressed. The worst cases I can remember were mostly ball moss jobs. Ball Moss is a funny little plant, related to pineapples (bromeliads), and not actually a moss. It clings to trees mostly, but sometimes it appears on power lines or most anything that will give it access to moist air. We generally leave it alone unless a client insists on removing it for appearance's sake. But when it gets so prolific that it covers entire branches, the tree loses the ability to start new shoots (stimulated by sunlight) and as a result can sometimes suffer. When we pick these trees, often just when the branch is almost clean, it breaks--mostly I'm talking about the small twigs, maybe 1/4"-1/2" in diameter, though larger limbs seem more brittle, as well.

That was the Treaty Oak a decade ago. There was little or no ball moss, but the stress of the poisoning and the subsequent loss of a large portion of its canopy had the same effect. Brushing past interior growth, which I do routinely, had to be done very carefully so as not to snap out excessive amounts of leaves and twigs. It was a long, challenging day.

Today, I think the tree is much stronger. I noticed a lot of bark tearing out around the base of cuts in the northwest section of the tree, but not much twig snapping. In the eastern section, I did not really encounter either of these problems. The biggest issue faced by the tree today seems to be squirrels. I used to think of squirrels as cute little fuzzy wildland critters. After 15 years of caring for trees, I have learned to view them as a scourge. We arborists often refer to them as tree rats. They chew bark off of branches, mainly at the point of attachment, until they either completely girdle and kill them, or until they are so weak that they have to be removed even if they are alive. Then the tree sends up clusters of new sprouts to replace them, which make nice baskets to hold the rats' nests. The nests trap moisture against the bark, which can lead to more problems. I knock them out whenever I can.

I left several squirrel-damaged limbs on the Treaty Oak that I would have cut on another tree, for several reasons. First, the tree might be stronger than it was, but we still treat it with kid gloves to avoid additional stress. Second, there was so much of this kind of problem that we would not be able to take it all in one pass even if the tree were stronger (generally, the recommendation is to take no more than one-third of a tree's live canopy at one time, but I try to avoid crossing the 25 percent mark except in rare cases, such as overmature Arizona Ash--Fraxinus velutina). Third, there were cameras and City staff and passersby everywhere, and I didn't want to set the example that it's okay to just rip out tons of green tissue--this is a common practice among poorly trained climbers, sometimes called lion tailing, which is very hard on trees.

So we removed the clearly dead branches and a few of the worst cases of live-but-squirrel-damaged limbs. We also took out a few live limbs that were rubbing on another branch. Like with the squirrel problems, there were too many rubbing limbs to take anywhere near all of them. But we did take the worst examples, since they can lead to open vascular wounds that could contract oak wilt or another disease. Finally, we removed part of a low branch that was growing over the top of the adjacent Treaty Oak clone, planted a few years ago. This smaller tree was meant to replace the sections of the large tree that were lost in the poisoning. By cutting back some select branches, we gave the smaller tree some breathing room and helped reduce the extent that it becomes misshapen over time.

All this, and we were out of the tree in time for lunch (the non-volunteer City crew had to stay and clean up). As a tree that has been maintained consistently for years, the Treaty Oak has a nice, open interior canopy that is fun to climb around in. I really enjoyed the day and hope I can get into the tree again before another decade passes.