Nasty Little Buggers

The damn bark beetles killed my tree! Argh! If you've driven up to Santa Fe recently, I'm sure you've noticed that my tree wasn't the only casualty of this pestilence. Over the last couple years, New Mexico has been transformed into a piñon graveyard, and we have those nasty beetles to thank for it.

Mark Rix holds degrees in microbiology, biochemistry and technology management. He's done a lot of research on the Southwest's recent bark beetle plague, and he recently published a handy little guide on the subject called Beating the Bark Beetles. The Alibi recently had an opportunity to chat with Rix about this horrible scourge.

“When I moved to Santa Fe back in 1999,” Rix says, “I was only in my house for six months when I started losing trees. I owned a one-acre lot, and I was also overseeing a 3.5-acre property for a friend of mine. I started asking around, and nobody could say what was causing it or how to eliminate further losses.”

Rix paid landscapers to replace trees and was told that at least 50 percent of those replaced trees would also probably have to be replaced. Rix eventually found out that this was because they were getting new trees from areas that were already infested with the beetles. For this reason, it was almost a certainty that the new trees would be lost.

“What's really disturbing,” Rix says, “is that even before beetles got to the area, they were being brought in by landscapers. I lost older established trees, too, because of this. By the fall of 2001, I'd lost over 350 trees on my friend's property. I had to take out 63 trees on my acreage. Some of them were absolutely huge trees.”

According to Rix, piñon trees can live a very long time. Some have been tree-ring dated at over 900 years old.

“I had to take out some trees with trunks over 32 inches in diameter,” Rix says. “And I fared better than some of my neighbors. Many lost over 90 percent of their trees because they had south- or west-facing lots that received a lot more heat during the summer.”

No one seemed able to give Rix answers. “I got a lot of cryptic and strange responses,” he says. “In retrospect, it seems that everyone had a piece of the puzzle, but no one put it all together. A lot of people believe it's the bark beetle that kills the tree, but this isn't true. The beetle just initiates a sequence of events that eventually kills the tree.”

The adult male beetle carries the spore of the Blue-Stain Fungus. When the beetle successfully invades a new host tree by boring through the bark into the inner layers of the tree, these spores rub off its shell, then they germinate and begin to grow.

“As the beetle bores in,” says Rix, “the tree starts clogging its own capillaries with sap to push the beetle out of the tree. If there isn't enough sap pressure because of drought, then the beetle can dig deeper bringing the spores along with it.

In this way, the infestation is massively exacerbated by drought, because a drought-traumatized tree is incapable of producing enough sap to push out the beetle. Yet, according to Rix, drought isn't the primary cause of the infestation.

“Within the last 1,000 years, we've had four devastatingly severe droughts in this area,” says Rix. “The last severe drought was in 1773. But we're taking out trees that are 600 to 800 years old in some cases. These trees survived droughts far worse than the one we're going through now.”

Rix also points out that both bark beetles and the Blue-Stain Fungus are native species. In other words, they aren't a new problem. So that begs the questions: If these older trees have survived severe droughts before, why are we suddenly looking at a potential 85-percent loss of piñons in New Mexico?

“If you look at the chain of events that most likely caused what we have now,” Rix said, “you have to start with the way land use in the Southwest changed 150 years ago. Grazing practices changed. Natural grasslands, which are now bare, used to be rolling prairies. When we came along, the ecosystem changed dramatically. We concentrated domestic livestock in these areas. This led to overgrazing. Even today, if you drive between Santa Fe and Albuquerque, the fenced-off areas enclose land where virtually no grass exists anymore.”

Rix says that cattle won't eat piñon and cedar. The destruction of grass lands has allowed these trees to invade these over-grazed areas en masse. Rix believes that we simply have too many piñon and cedars for our arid land to support, and that this has amplified the infestation.

According to Rix, the second major cause of the infestation is rooted in the way we began controlling wildfires about 100 years ago. “We have Smokey the Bear syndrome in this country,” Rix says. “We want land that's densely forested, but we don't want forest fires. For forests to be healthy, though, fires are a good thing. For one thing, they thin out fuel. Massive fires like the Cerro Grande Fire were caused because there were 200 to 300 trees per acre where ordinarily there would be just 20 to 30. That concentration leads to overcrowded, weaker trees. Then, when a fire becomes massive, it gets into the crowns of the trees. It burns hot and fast. Even trees that aren't burned by the fire are severely damaged. This, in turn, allows bark beetles to infest even more easily.”

Beetles can fly far, so the infestation spreads fast. “If we don't have a strong hard winter,” Rix says, “the beetles don't get killed off, and hot, dry summers lead to a much higher beetle population.”

So how do we protect our trees? “If the tree has already been infected by the Blue-Stain Fungus, it's as good as dead,” Rix says. “There's no way to kill the fungus without killing the tree.” In his book, he gives advice to readers eager to protect trees that haven't yet been infected.

“Every time we try to control things or make it better,” Rix says, “we don't see how our actions will come back to haunt us. I've learned that every time we try to make something better in terms of land management, we can't. Nature's just trying to recover and get back to equilibrium.”