There had been this aspen tree leaning over the driveway at WC’s house in Fairbanks for some months. It wasn’t an alarming lean; just a bit of an angle. But there were dead branches in top of the tree, that slight lean was towards the house and Mrs. WC had been after WC to do something about it before winter set in. So, on a Saturday morning in late autumn, after the leaves were down, WC got the chainsaw out of the shed and attended to the tree.
Aspens – the late Joe Vogler called them “arboreal weeds” – are a transition species. The mature forest on the south-facing hills around Fairbanks is mixed White Spruce and Alaska Birch, but the mature forests were most cut down for firewood to heat and light Fairbanks before the Alaska Railroad brought Healy coal to town. Will Putnam joked to WC one time that there were only half a dozen individual trees on the hills north of town; with hundreds of clones. Maybe so, but some of the aspens have gotten pretty large across the decades. The leaner on WC’s driveway was about seven inches in diameter.
WC wants to emphasize he’s had a fair amount of experience with a chain saw. A tree will generally drop pretty much where WC wants. So WC approached this with moderate confidence,
But at the first cut, maybe half an inch in to the seven inch trunk, the tree started to fall. Right towards the corner of the roof of the garage. As the tree went over, the trunk just above the small chain saw cut shattered. It was honeycombed with carpenter ants. The trunk of the tree struck the garage roof about three feet in, and the tree just exploded. Fragments of rotten wood, dust, carpenter ants, larvae and aspen tree descended in a cloud at least fifteen feet in diameter, along with the top of the tree.
WC, once the adrenaline ran down, attempted to be methodical. First, WC sprayed the carpenter ants with soapy water mixed with boric acid. There were a lot of them. The 2.5 inch long queen was exposed. The nest extended from just above ground level to about 25 feet up the tree. Most of that length, the tree was a thin shell of sound wood, half an inch or so, around honeycombed heartwood. It’s astonishing the tree did not collapse. The tree got bucked up in to manageable lengths and loaded into the pickup – there was no question of using it as firewood. – and hauled it to the transfer station. WC raked up rotten wood fragments, carpenter ant corpses and shrapnel that seemed to cover most of the driveway. And WC replaced six roof shingles, the only thing damaged when the tree struck the corner of the roof. The tree missed the rain gutter by less than an inch.
It could have been a lot worse.
There was nothing in the exterior of the tree to indicate it was an ant-ridden zombie tree corpse infested with several thousand ants. But it makes you wonder how many other mature aspens on the hillside are similarly infested. And it makes you wonder whether the warming climate will aggravate the problem. Warmer winters may increase survival of carpenter ant colonies or weaken trees adapted for the colder temperatures. Alaska’s carpenter ants, Camponotus herculeans, don’t eat wood; they aren’t termites. They bore trees to make their nests. Sometimes they leave little piles of sawdust. But – and trust WC on this – not always.
A couple of years later six aspens were removed to allow construction of a new drain field for the house. Two of those six trees had carpenter ant infestations, although none as large as the one WC found.