Glossy Privet: Slayer of Native Shade Trees

Every weekend I walk through the woods of Walnut Creek Metropolitan Park to see how things are turning out for the trees we have girdled and the plants we need to grow in their place. The first weekend of July 2019 I came across a large live oak, shown in the second picture below, that is suffering the damage glossy privets do to larger shade trees:

  • They fill every bit of open space. Everywhere you look up under this oak, you see the leaves of glossy privet.
  • They grow year-round, piercing the oak's canopy.
  • As they grow into the canopy, they shade out—and kill—all the branches they pass by. In this oak, one large branch has died and is hanging in the canopy. Another large branch above it is dying, if not already dead. Both are in the shade of the same four glossy privets.
  • In Central Texas, glossy privets grow to be at least 40 feet tall. That's taller than our treasured live oaks. In fact, glossy privet competes with or towers above every species of tree found in Walnut Creek Metropolitan Park other than our pecans. And it can compete with pecans enough to do serious harm. For example, the pecan shown in the first picture below lost all of its leaves below 30 feet to a dense stand of glossy privet that grew in its shadow. (I'll have more later about the grove where this tree grew.) And for this live oak, it means that the glossy privets are already just as tall and are about to break above it, taking the first bite at the available sunshine.

    Whenever I see a native shade tree in this condition, it becomes an immediate priority. Instead of continuing our march through the woods on the other side of the trail, this weekend we focused on saving this tree.

    In three hours, three of us managed to uproot 27 Nandina domestica and girdle each of the 46 trunks of the 13 glossy privets (Ligustrum lucidum)—that's right; in the same area taken up by the canopy of this one live oak, there are 13 glossy privets—and to reach half of them we had to uproot the Nandina first.

    So today, July 13, 2019, this live oak's chance to recover begins. Over the coming year, I will report on the response of the glossy privets to their girdling and the response of this tree to its increasing access to all the available sunlight.

    Posted by baldeagle baldeagle, July 19, 2019 23:10

    Observations

    Photos / Sounds

    What

    Pecan (Carya illinoinensis)

    Observer

    baldeagle

    Date

    May 12, 2018 04:28 PM CDT

    Description

    This large tree rose above the glossy privets—but has lost every leaf and lateral branch below the top of their canopy. Hopefully now that much of the privet has been removed it will add at least some new growth at these lower levels.

    Photos / Sounds

    What

    Live Oaks (Section Virentes)

    Observer

    baldeagle

    Date

    June 16, 2019 03:10 PM -05

    Description

    This live oak is being shaded out by 13 glossy privets that sprouted beneath its canopy over the years. A large limb is dead, broken away, and hanging in a juniper. Above it, another large limb remains attached, but seems to also be dead. On July 13, 2019, we girdled each of these privets. Over the coming year, we will see if they die away and, if so, how the live oak responds.

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