At 37:30, Darrell says that Chinese tallow is not a problem in Central Texas. I will concede that it is not as widespread a problem here as elsewhere, but I suggest he take a hike along the lakeshore at Commons Ford Metropolitan Park and then reconsider the question of whether it is "a problem" in Central Texas. That monoculture thicket should leave no doubt.
At about 30:30, the girdling technique shown is excessive. It will be prone to failure. Because the worker has cut deeply into the sapwood, the flow of water to the treetop will be restricted at the girdle. Any water that cannot get through the girdle will be available to support photosynthesis in the sprouts that will form below the girdle. Girdling kills a tree by keeping the root system overworked and underfed. "Overworked" means the root system will still have to support every leaf and bud that it was supporting before the tree was girdled. "Underfed" means that it is getting none of the sugar the tree produces. After a while, the root system will die of starvation. When it does, the treetop will soon die. People who try to girdle trees undermine this process in a couple of ways. Cutting the canopy back is one. It's tempting to prune branches or weaker trunks out of the way to make it easy to work on the bigger trunks. But if you do that, the root system won't be overworked. It will be able to produce enough water to support the canopy you left plus the canopy you removed. The water that would have been used up by the canopy you removed will be able to support new growth below the girdle. The leaves on that new growth will feed the root system. Because we didn't keep the tree overworked, it was able to fix the problem of being underfed. The tree will survive. The other way people frequently undermine this process is to remove not just the phloem from the girdled area but also the sapwood below it. In this video, the worker cut into the sapwood at the top of the girdle-and cut way too deeply into the sapwood at the lower end of the girdle. The tissues they removed are needed to carry the water produced by the root system up to the canopy. Now that they have been cut away, the root system will not be overworked. Instead, the top will be underwatered. It will wilt quickly. As it wilts, the root system will supply the water the top needs to buds and sprouts between the base of the tree and the bottom of the girdle. The leaves on that new growth will feed the root system all the sugar they can spare. Before long, the root system will be neither underworked nor underfed. The tree will survive. Fortunately that is not how Austin Water Wildlands Conservation teaches its volunteers to girdle trees. The girdling method they use leaves the sapwood intact. The roots stay overworked until they starve. Then the top does.
Hi Cliff, thanks for your keen eye and for weighing in. If anyone here is looking to learn how to girdle invasive trees, check out this video that we made with Cliff to show proper girdling technique: th-cam.com/video/R-L1RJn095w/w-d-xo.html
Although the two species both have the same traits that make them invasive, the small-leafed privet shown in this video and found widely throughout the BCP is not Chinese privet (Ligustrum sinense). It's Quihou's privet (Ligustrum quihoui). Wherever the soil is alkaline clay, Quihou's privet is dominant. It does not seem to tolerate sandy or acidic soils, so in Bastrop County you will find little if any Quihou's privet among the thickets of Chinese privet. Chinese privet can be found but is not widespread in the general area of the BCP.
At 37:30, Darrell says that Chinese tallow is not a problem in Central Texas. I will concede that it is not as widespread a problem here as elsewhere, but I suggest he take a hike along the lakeshore at Commons Ford Metropolitan Park and then reconsider the question of whether it is "a problem" in Central Texas. That monoculture thicket should leave no doubt.
At about 30:30, the girdling technique shown is excessive. It will be prone to failure. Because the worker has cut deeply into the sapwood, the flow of water to the treetop will be restricted at the girdle. Any water that cannot get through the girdle will be available to support photosynthesis in the sprouts that will form below the girdle.
Girdling kills a tree by keeping the root system overworked and underfed. "Overworked" means the root system will still have to support every leaf and bud that it was supporting before the tree was girdled. "Underfed" means that it is getting none of the sugar the tree produces. After a while, the root system will die of starvation. When it does, the treetop will soon die.
People who try to girdle trees undermine this process in a couple of ways. Cutting the canopy back is one. It's tempting to prune branches or weaker trunks out of the way to make it easy to work on the bigger trunks. But if you do that, the root system won't be overworked. It will be able to produce enough water to support the canopy you left plus the canopy you removed. The water that would have been used up by the canopy you removed will be able to support new growth below the girdle. The leaves on that new growth will feed the root system. Because we didn't keep the tree overworked, it was able to fix the problem of being underfed. The tree will survive.
The other way people frequently undermine this process is to remove not just the phloem from the girdled area but also the sapwood below it. In this video, the worker cut into the sapwood at the top of the girdle-and cut way too deeply into the sapwood at the lower end of the girdle. The tissues they removed are needed to carry the water produced by the root system up to the canopy. Now that they have been cut away, the root system will not be overworked. Instead, the top will be underwatered. It will wilt quickly. As it wilts, the root system will supply the water the top needs to buds and sprouts between the base of the tree and the bottom of the girdle. The leaves on that new growth will feed the root system all the sugar they can spare. Before long, the root system will be neither underworked nor underfed. The tree will survive.
Fortunately that is not how Austin Water Wildlands Conservation teaches its volunteers to girdle trees. The girdling method they use leaves the sapwood intact. The roots stay overworked until they starve. Then the top does.
Hi Cliff, thanks for your keen eye and for weighing in. If anyone here is looking to learn how to girdle invasive trees, check out this video that we made with Cliff to show proper girdling technique: th-cam.com/video/R-L1RJn095w/w-d-xo.html
Although the two species both have the same traits that make them invasive, the small-leafed privet shown in this video and found widely throughout the BCP is not Chinese privet (Ligustrum sinense). It's Quihou's privet (Ligustrum quihoui). Wherever the soil is alkaline clay, Quihou's privet is dominant. It does not seem to tolerate sandy or acidic soils, so in Bastrop County you will find little if any Quihou's privet among the thickets of Chinese privet. Chinese privet can be found but is not widespread in the general area of the BCP.