Girdling: What's It All About?

Fully vaccinated but still careful to mask up, I am trying to get back in a rhythm of assailing invasive trees in my vicinity. If that sounds like something you would like to do, a good start would be to watch the instructional video on girdling glossy privet a good friend of mine, Dave Dauber, produced for the Austin Water Department's Wildlands Conservation Division.

This video shows how to girdle trees by the method I developed for volunteers in Austin's Walnut Creek Metropolitan Park. Using no herbicides and no power tools, we have killed all the mature ligustrums on more than 20  of the park's forested acres.

What's so special about this method?

Following techniques taught elsewhere, I and other volunteers like me found that girdled trees almost always recovered fully. (Actually, I can't recall a single tree that didn't fully recover.)

Others gave up on the technique, but after the third variation failed, I returned to the job site daily to monitor the recovery of the girdled trees. Right away I learned that the tissue that bridged the girdle wasn't growing in from the ends of the girdle. Instead, it was growing from tissue left behind on the surface of the sapwood in the girdled gap.

In other words, we didn't need a tool that was sharper or larger or more powerful. Instead, we needed to make sure we removed every cell of tissue from the trunk in a band at least 3/4 of an inch wide:

  • It turns out that it's easier to remove a wider strip of bark, so we remove about a hand's width.
  • If the tree has forks, you can girdle each trunk at a convenient height, so long as every leaf remaining on the tree is separated from the ground by a girdle.

Need more details?

For the details on why girdling works, what tools to use, where to get them, and other techniques for eradicating invasives, check out my presentation to the 2019 annual meeting of the Texas Master Naturalists. This PDF of the slide deck includes not just the slides my audience saw but also what I said while they were displayed and information added to answer questions raised by the audience. It is pretty thorough. The PDF is weird; somehow in creating it they wound up with the images at the lower right corner of each screen, but the information is complete.

Got massive trunks?

Girdling works no matter how large the tree is. I've stripped individual trunks up to 26 inches in diameter (a chinaberry), and I've girdled trees with a combined diameter at breast height of 42 inches. When the bark gets really thick, you might need a bigger tool. Watch how backyard birder Jeff Hansen of South Dakota can remove thick bark with a pry bar.

Even with trees as big as Jeff's, I suggest you add my final step of scrubbing the residual phloem and cambium from the surface of the sapwood. You can get by with scrubbing a band just a couple of inches wide, so long as it goes all the way around the trunk. As with peeling the bark, wider is usually easier, but if the pry bar removes a whole foot-wide strip of bark, you don't have to scrub the whole width.

Now get out there and kill some privets!

Publicado por baldeagle baldeagle, 23 de noviembre de 2021

Comentarios

Thanks for sharing, Cliff! Very informative!

Publicado por wetlandfan hace 7 meses (Marca)

Hope we can get back to work here asap. Surveying what we've already accomplished is mind boggling and our enthusiasm and pride in achievement is only tempered by how much more we have to do before we can truly say we've accomplished our goals! Thanks for your great help and support. Hope we can meet up again soon.

Publicado por billarbon hace 7 meses (Marca)

That would be great, Bill! By the way, I have found one large L. lucidum that was killed by February's deep freeze. I, too, am amazed at how much we have accomplished. Several places that seemed like we would never get under control have only a handful of fruiting privets. Small teams, or even people working solo, can knock out the stragglers. We will have to periodically sweep for regrowth, but because it takes several years—and maybe more than five; I'm not yet certain—for a new sprout to get mature enough to bear fruit, we have more than a fighting chance to keep these areas clear as we move on to others.

Publicado por baldeagle hace 7 meses (Marca)

In our case we've really made headway against the Chinese Tallows and the Ligustrum. Even the trees damaged by the cold, but survived will not be able to reseed the area as easily as before. The impact we've had on the Chinese Tallow can be seen in photos on both Flickr and my messages soon. In the meantime the city is discussing passing the tree ordiance. In the meantime, I am trying to round up younger volunteers to take over for me. I can't keep this up forever. I'm old.

Publicado por billarbon hace 7 meses (Marca)

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Vida Silvestre es una entidad asociada a la Organización Mundial de Conservación