A ponderosa pine approximately 200 years old in north Durango could be irreparably damaged from construction of the Animas River Trail northern extension, but it’s better than the alternative, city officials said.
City contractors have pruned the roots of one of the oldest trees in Durango to make way for a 4,600-foot extension of the Animas River Trail from Memorial Park near 32nd Street to Oxbow Park and Preserve. Ponderosa pines grow slowly, especially when they’re as large as this one, and the damage caused by cutting roots might not manifest for years, said Jim Lyman, president of Animas Valley Arborists.
“It’s hard to say what the long-term effects might be,” Lyman said after visiting the construction site to assess the tree. “It’s not a certain death; it’s not certain that the tree will live.”
Durango Parks and Recreation landscape architect Scott Chism said the potential damage to the tree was a risk the city was willing to take – it’s better than removing the tree altogether. The corridor for the Animas River Trail extension north is narrow and sloped, and Chism said city staff tried to align the trail as far away from the tree as possible – a difficult task with such a large tree.
Construction of the trail is occurring within the tree’s “dripline” – the area under the outer circumference of the tree’s canopy – something Lyman warned against. The dripline is also called the critical root zone, and if too much of that is damaged, it could compromise the tree.
In this case, the city had no choice but to work within the pine’s dripline, Chism said. City arborists determined that because there were no structural roots where the crews proposed to dig, the tree has a chance to live.
To improve that chance, city crews installed a concrete retaining wall to hold up the soil the tree is anchored in, Chism said. That shoring isn’t cheap, he said.
“The city is spending a lot of money to allow the tree and trail,” Chism said.
But the city could be doing more, Lyman said. Putting mulch around as much of the tree roots as possible ensures that the tree gets additional nutrients, that the soil doesn’t dry out and that weeds don’t grow and take water from the tree. Digging around a tree’s roots also stresses the plant, making it more susceptible to pests like the bark beetle, so a pesticide could help the tree.
The city arborist takes care of all trees in Durango, and the trees along the Animas River Trail north extension are no different, Chism said. If trees along the trail start to die, it’ll be up to the city arborist to decide what to do.
Until then, construction continues.