Why can’t we just (sniff) wipe out Austin’s (achoo!) cedar trees?


Highlights

The mountain cedar throws off awful pollen — but it probably can’t be killed off, and maybe shouldn’t be.

Mountain cedar is not an invasive species, despite widespread belief to the contrary.

Admit it: You wish someone would wipe out the mountain cedar.

The Hill Country tree throws off a thick, pernicious pollen that triggers a widespread allergy, cedar fever, that feels even worse than it sounds. The trees are adapted to suck away water that would otherwise feed other plants. It’s also a particularly worrisome fire hazard during the droughts that afflict Central Texas from time to time.

Thursday’s cedar pollen count in Austin was high: 1,501 grains per cubic meter. But it was off the charts intense in Round Rock, where levels reached 23,559 grains per cubic meter, according to local allergists.

So why do we allow mountain cedar, aka Ashe juniper, to persist? Two experts explain:

Why doesn’t Central Texas just wipe out the mountain cedar?

Basically, we can’t, said Jim Rooni, the chief regional forester and head of Central Texas operations for the Texas A&M Forest Service.

He said he gets asked about killing off cedar all the time. Lawmakers have asked on behalf of constituents about eliminating the trees. He can empathize with those suffering from cedar fever — Rooni suffers from cedar fever himself (imagine having that allergy when your job is to be out among the trees). But mountain cedar is so well adapted to Central Texas that about 10 million acres are home to it across the Edwards Plateau, Rooni said.

Some people — ranchers, for instance — do make an effort to thin the cedar, he said. But a 12-foot cedar is a hardy plant. Removing more than a few of them requires “expensive, mechanical means,” such as a bulldozer, Rooni said.

“Eliminating the cedars is a noble goal,” he said, “but impractical.”

Isn’t stopping an invasive species worth the effort?

Actually, mountain cedar isn’t an invasive species, despite widespread belief to the contrary. Botanists scouting the Hill Country in the 1800s found stands of cedar in canyons and along waterways, Rooni said.

It was man’s influence that set this pestilence loose. (Breath in the irony, all ye sufferers.)

Settlers brought cattle with them. The cattle ate too much of the blanket of grasses that once covered much of the Hill Country and held its topsoil in place. With the region overgrazed, hard rains washed away much of the soil, in turn hampering the ability of the grass to return.

That opportunity allowed the cedars to spread. They are naturally adapted to survive on rocky surfaces with little soil, a habitat that expanded dramatically over the course of a few generations. A cedar canopy is also particularly effective at catching rain before it hits the ground, stealing it away from other plants, Rooni said.

Isn’t cedar also a fire hazard?

Yes. But again, that is partly man’s influence.

“The savannas of Central Texas (used to burn) frequently as part of their natural cycles, and this kept juniper in check,” said Michelle Bertelsen, an ecologist with the Lady Bird Johnson Wildflower Center. Mountain cedar “is very susceptible to fire while it’s small.”

But as people moved into the region, they have tried to limit wildfires, for the sake of saving lives and property.

Most of the time, mountain cedar absorbs so much water that “it’s so green you can’t get it to burn,” Rooni said. When drought hits, however, the tree not only dries out, but the relatively high amount of resin the trees contain “make them very flammable,” he said. In developed portions of the Hill Country — where sparks can ride high winds, igniting fires that race up steep slopes — this is a dangerous combination.

Public safety agencies do occasional controlled burns and have made the case for doing more of them. But such steps will only limit the risk, Rooni said.

Shouldn’t we at least try to kill off cedar?

Mountain cedar, as out of control as it is, does have ecological benefits.

Old growth cedar, in particular, helps hold what’s left of the Hill Country soil together, Bertelsen said. It can be particularly important for minimizing erosion along the little, picturesque Hill Country waterways that would otherwise eat away at their banks. An endangered bird, the golden-cheek warbler, also needs cedar as a habitat, Bertelsen said.

“Careful thinning of cedar can be part of good land management,” she said, “but it must be done in a careful and thoughtful way. Complete elimination is usually not the goal.”

Rooni advises those dealing with cedar fever to seek medical help and then look to the wisdom of Maya Angelou: “‘If you don’t like something, change it. If you can’t change it, change your attitude’ about it. It’s one of the things Central Texans must endure … and (cedar fever season) ends eventually.”



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