Pining for piñons in the beetle battle
You can see a forest fire coming, but you can’t see what might wipe out the trees in my backyard canyon country. It’s a bug, a tiny beetle that flies with the wind. It’s an invisible force that lays waste entire forests.Ips, the “engraver beetle,” is a puny little reddish-brown to black insect 1/8- to 1/4-inch long. They have a pronounced cavity on the rear end that is lined with three to six pairs of toothlike spines. The larvae they lay are small and lethal to piñon pines.I cheered when the Beatles came in 1963, but not for these beetles. Their life instinct is girdling piñon pines, with which my greater back yard is abundant. So is most of the midvalley, and much of the West.The Ips beetles know not what they do, but entomologists sure do. Adults lay eggs along galleries, and once the larvae hatch, they feed just inside the bark and mine away the pupal chamber, killing the tree.Growing from egg to adult takes 21 to 40 days in summer and several months in winter. The beetles are dormant from November to March, but they make up for it by producing two to five generations per year.The beetles also introduce a “blue-stain” fungus that spreads and clogs the water and nutrient-conducting tissues of the tree. Once the insects mature, they leave the infested tree and travel to a new host. Their range is a kilometer or more.I noticed this epidemic a few years ago while hiking through the Colorado National Monument near Grand Junction. First I noticed a few scattered piñons with brown needles, then a few dozen. When I stood on a ridge and looked over an expanse of forest, hundreds were dead or dying.The forest in my back yard at Seven Castles is piñon-juniper, or “PJ.” Some of the piñon are ancient, their thick, gnarled trunks showing hundreds of years in age. Slow growers in this dry, red dirt, it will take centuries to replace them.Much of New Mexico and Arizona are currently experiencing a large upswing in piñon mortality due to low tree vigor caused by several years of drought. In the 1950s, there was a huge piñon die off in New Mexico related to a drought that altered the composition and age structure of piñon-juniper woodlands.According to Delia Malone, a biologist in the Roaring Fork Valley, the die off of piñon forests is already reducing populations of piñon jays, which depend on pine nuts for food. Other populations will also diminish as their habitat is altered.Piñon-juniper woodlands provide shelter and forage for piñon mice, woodrats, mule deer, bighorn sheep, elk, mountain lions, bears, gray foxes, bobcats, coyotes, weasels, skunks, badgers, and ringtails.Piñon jays, Stellar’s jays, and Clark’s nutcrackers all have a symbiotic relationship with the trees by eating their fruit and disseminating seeds in their winter caches. When bird populations plummet, so does the likelihood of tree regeneration, which slows to a crawl.The Ips infestation is a tragic, natural cycle. Droughts happen; so do infestations, die offs, blights, famines and plagues. It’s part of a deeper pulse, and it’s likely to happen in my back yard, where up to 90 percent of the piñons could die.So what can I do? Watch it happen. Observe the changes. Mourn the loss. Ultimately, I must accept the insect phase, knowing that cycles play out and life goes on far beyond my lifetime.”Trees will drop those red needles, creating a natural mulch that will begin to build up the soil,” writes permaculturalist Bill Mollison. “Dead standing snags will offer shelter from weather and perhaps shade for a young replacement sapling. “Insectivore birds, like downy woodpeckers and red-shafted flickers, will busy themselves hunting wood borers and grubs or perhaps drilling cavity nests to inhabit. Other smaller birds will benefit from the woodpeckers’ work. Dead wood is critical to whole system forests, a primary element. Dead trees provide for the entire forest.”Paul Andersen will try to see the forest for the trees, even when they’re gone. His column runs on Mondays.
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