TWIN FALLS – City Park is home to about 113 trees. Most of them are full, towering giants with massive trunks, creating a lush green canopy that casts cool shadows on hot summer days.
Photos of City Park from a century earlier show a different scene. In the photograph, skinny, spindly, freshly planted trees can be seen, standing in rows along the open field.
Maintaining health and planning the future of this “urban forest” is part of the job description for Chance Munns.
As the new Parks and Recreation superintendent for Twin Falls, Munns oversees the maintenance and upkeep of all the city’s parks and facilities and common areas. A big chunk of the job involves thinking about trees.
A certified arborist and landscape architect, Munns knows that trees face a number of threats from the time they are saplings until they are fully mature – a process that often takes several decades. Young trees need to survive damage from vandalism or abuse, and resist pests and extreme weather, among other things.
Current city ordinance requires that if a public tree is removed, it needs to be replaced. Although there are some fast-growing trees, the desirable trees are usually ones that take a long time to mature. Replacing a mature tree doesn’t happen overnight.
It takes about 30 years for maturity in most tree species, Munns said. Some take longer, and others less. But, usually, the fastest growing trees use a lot of water and don’t live all that long. Trees like poplars and willows are restricted and are not permitted to be planted in the city rights of way.
“However oaks and bristlecone pines take a long time to mature, and they are slow growers, and those are the ones we want,” Munns said. “So we’re planning for the long-term future of our urban forest, something that will last a long time and resists pest and disease problems.”
The tree commission developed a Tree Selection Guide in 2000 to offer suggestions to the public for trees that do well in our region. It also serves as a list of acceptable or encouraged trees for public spaces.
Munns said he would like to see the guide updated to help form a long-term plan for improving tree diversity. He has been developing a list of trees he would like to see incorporated into the urban canopy: “Trees that we don’t see as often around here but that should do really well, and that would increase our diversity and population.”
The Tree Selection Guide was last updated in 2006 and Munns thinks it’s time for a revision.
“If we’ve been planting those same trees for 16 years we ought to update it and change it so we start planting other things,” Munns said. “New, heartier cultivars have been introduced that better tolerate our alkaline soils and cold climates and so we can start to use those, and I think some were just kind of missed out on.”
A few examples Munns gave for trees he’d like to add to the future Tree Selection Guide would be trees from the Ginko family, which are resilient to environmental upheaval, and don’t have pest or disease problems.
Another tree Munns said he’d like to see more of is the Dawn Redwood. With a fun-to-say Latin name of metasequoia glyptostroboides, it is the shortest redwood tree.
It does OK in our climate, and also has no pest or disease issues, but it is a deciduous conifer, so it looks evergreen with needles, but the needle turns yellow and falls off every year, so people think their dying, but that’s just what they do, ”Munns said. “In my mind, they are desirable to have around.”
For Munns, increasing the diversity of the urban forest is key to building resistance to pests and diseases.
“If we can increase our diversity and have multiple species in our urban forest, that slows down any kind of pest or disease spread,” Munns said.
Pests such as the emerald ash borer, an invasive destructive beetle that rapidly reproduces in the bark of ash trees, is responsible for nearly 100% fatality for the trees it infects. The emerald ash borer was found in Colorado in 2013, and by 2020 had a solid foothold. The “most destructive pest” is expected to be found in Idaho as soon as this year.
According to an inventory of public trees in Twin Falls, green ash is the most prevalent tree in our parks, with 173 trees counted. Most of them are large, mature trees that have been alive for many decades. Once the emerald ash borer arrives, there is very little that can be done to save the city’s ash. Treating the trees for pests can slow down the spread and help trees stricken with the borer to survive a few more years once the emerald ash borer hits. Ultimately, experts say – and experience has shown – those trees are going to die.
But until that happens, the biggest threat to tree health in Twin Falls is people. According to Munns, the biggest cause of tree deaths in public areas is an incidental misuse by the public.
Usually, the younger trees fall victim to being climbed on before they are strong enough or suffer greater damage when slashed. Those trees aren’t just quite ready for that kind of abuse yet.
“I’m a person who loves to climb trees, so I would never get after anyone for wanting to climb a tree,” Munns said. “But on young ones, they can’t quite tolerate it yet. The limbs will break under that weight. ”
Vandalism has been an issue and Munns said it will keep being an issue.
Last fall there were a number of incidents of people striking trees with bladed tools, like hatchets – or knives or even swords – and that is an activity the city wants to discourage.
“That kind of damage we continue to see quite a bit,” Munns said.