Habitat Snatchers

Invasion of the Habitat Snatchers

by Margaret Canavan,
GITC Board Member, Galveston Co. Master Gardener

Courtesy: Galveston Daily News, Published October 30, 2013
Here’s a question: What would you think of a plant that is illegal to sell, distribute or import into Texas, spreads rampantly while crowding out native vegetation, and is difficult to eliminate? No, it’s not Audrey from the “Rocky Horror Picture Show.”

This tree, Triadica sebifera, is the Chinese Tallow, also known as the “Terrible Tallow”. While legend credits its US introduction to Benjamin Franklin, it’s no friend to us on the Gulf Coast because it adores our mild climate far too much. Recent Texas Forest Service statistics show that in Galveston County since 1970, woodlands containing monocultures of the invasive tallow have increased in area from 5 to 30,000 acres. Over a fifth of all trees in the Houston area are Tallows, more than any other tree species. Click here for a U.S. Geologic Survey Fact Sheet.

The tree does have its fans. Tallows offer colorful fall foliage. They are fast and easy to grow and are decent small shade trees (although its limbs and branches break easily). Local beekeepers consider them an excellent nectar source for honey production. Also on the positive side, they have been grown for centuries in China for seed oil, used for making candles, soap, cloth dressing, and fuel. Oil from Chinese tallow trees was used successfully as an emergency source of fuel for diesel equipment operated by Allied forces during World War II.

So why do poor Tallows have so many detractors? They are aggressive and tenacious land-grabbers. They spread by root fragments and cuttings, so are quick to invade after a hurricane. Tallow trees begin producing viable seed after only three years, and just one tree can produce 100,000 seeds annually. Trees can remain productive for 100 years. Even one tallow tree presents a danger of explosive expansion that can harm local ecosystems by crowding out native vegetation.

Tallows are extremely difficult to eradicate. Freezes can damage the trees but roots are rarely killed. Bulldozing is ineffective because it results in sprouting from roots. Fire can successfully eliminate small trees, but larger trees tend to resprout. To be effective, herbicides must be applied repeatedly and it is estimated that it costs about $250 per acre to control such exotic plant species.

The Texas Department of Agriculture lists Chinese Tallow as one of our 24 most invasive plants and includes it on the agency’s list of Noxious and Invasive Plants. The Tallow invasion has contributed significantly to the degradation of wetlands along the Gulf Coast. Chinese Tallow may even alter soil chemistry, allowing the species to self-perpetuate once established. Insects, diseases, and other natural enemies have little if any impact on our pesky friend. In the agricultural realm, it is toxic to cattle while crowding out their preferred grazing foods.

So are the benefits of Tallow worth the high environmental cost? It may have a useful place in the US, but it's not on the Gulf Coast. Surely there are better choices for shade trees. Galveston residents can pick up two free trees at the Galveston Island Tree Conservancy tree giveaway on November 16. And none of them will be Tallows.

Hurricane Ike caused the loss of 40,000 trees on Galveston Island. The Galveston Island Tree Conservancy was formed to address that loss and to date has replaced almost 11,000 through grant-funded plantings and giveaways, with more planned.

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“Tree Stories” is an ongoing series of articles about island trees, tree care and tree issues. If you have or know of a special tree on Galveston Island that should be highlighted, email treesforgalveston@gmail.com. Margaret Canavan is a Galveston resident, a Galveston County Master Gardener, and a member of the Galveston Island Tree Conservancy Board.