Arbor days: Tree experts weigh in on tree care following devastating storm

March 2021 Posted in Uncategorized

By Melissa Wagoner

Within hours of the ice storm horticulturist Eric Hammond began walking, covering as many miles of Silverton’s streets as he could, cataloging the trees – the ones that were damaged, the ones that were toppled and the ones that made it through relatively unscathed.

“I’m up to 3,300 different survey points and 130 different species,” Hammond said. “Fully 50 percent of what I see has got moderate to severe damage. And I’m only surveying the planted trees. The wild trees are their own thing to talk about. They were here before us and it’s sort of on us if we built a house there.”

But planted trees, largely chosen by homeowners, landscape architects or developers, are an entirely different matter, one Hammond feels some responsibility around, having worked in the nursery industry for many years.

“Planting a tree is a really complex thing and it does a huge disservice to everyone to avoid the nuance there,” Hammond stated, likening the choosing of an urban tree to that of footwear – in that there is no one-size fits all option.

“Say what you will, but that tree isn’t responsible for our choices,” Hammond wrote in a series of Facebook posts which chronicle his studies. “[W]e choose what trees to plant in our gardens and on our streets. Growing trees with a proven record of resilience, trees that do not damage the sidewalk or endanger the power lines is our collective need.”

Fortunately, there is a vast amount of research depicting which trees grow best in which environments. And most cities – Silverton included – provide lists of trees approved for urban planting.

“The city specifically has a list of trees and the street codes,” Glenn Ahrens, an Extension Service Forester with Oregon State University for the past 20 years, confirmed. “They usually have a list of ‘do not plant these’ as well because they have experience of which cause problems with infrastructure.”

Another good rule of thumb, when deciding upon which variety of tree, or other plants, to plant is to first consider native varieties.

“I wouldn’t say don’t plant non-natives, but natives are a good way to go,” Ahrens said.

But even amongst natives all trees are not created equal and research may be necessary to determine what varieties grow best in a specific region.

“Even amongst our native trees it’s pretty easy to transplant a tree from southern Oregon to northern Oregon for example and those are not a good match,” he said. “They’re not adapted to the climate.”

That climate is steadily changing, much faster than the trees themselves, making choosing a tree that can withstand a relatively rare event – like the recent ice storm – a difficult proposition.

“Trees evolve over many millennia,” Ahrens said of the current situation in which tree evolution is often being outrun by changes in temperature. “A lot of our trees are overwhelmed whether they’re native or exotic.”

It’s a tricky situation, one that could leave many home and business owners feeling like tree replacement is a bad idea. Which is a dangerous mindset, according to Ahrens.

“The recovery of the urban forest is really important. You just really want to match the stature of a tree and be careful, especially with proximity to buildings, sidewalks, it’s a real trade-off. There’s always a trade-off of the benefit of that big beautiful tree and the potential for damage and mess.”

It’s a trade-off that can be managed, however, with
care, maintenance and, in many cases, the help of professional arborists.

“All of the service providers are overwhelmed and people

are in a hurry to clean up and fix things up,” Ahrens said of the current situation, which he fears could turn dangerous due to home pruning by novices.

“You want to take the time and do it right and get the right help and be careful not to try to do it yourself,” he said. “We’re all tempted to do those things. But the word to the wise is – don’t go there. Get the help you need.”

And for those with trees completely uprooted by the storm? Unfortunately, even a professional will not be able to save a completely downed tree – especially ones larger than three feet.

“[W]hen your tree falls over, you absolutely cannot save it,” Hammond wrote in a recent post, acknowledging that, although it is tempting, even the most creative fixes will most likely be to little avail.

“The reason your tree fell over was a bad root system with too much top weight,” he pointed out. “A bad root system, on an established tree, cannot be fixed. You cannot right and re-stabilize the tree. That includes using ratchet straps (seen it), ropes (seen it), stakes (seen it), bricks (this too), or any other unique device (car, umm, yes, even this) to stabilize your tree.”

Why were so many of these uprooted trees oaks? For that, Hammond has another theory, one that has little to do with nature and more to do with care.

“Oregon oak requires summer drought, winter wet,” he wrote. “The toppled trees have root rot. We killed them with irrigation… Irrigation is deadly to these big old Oregon oaks. You cannot have an ancient oak and irrigated space. Not possible… Do not irrigate near an old oak. If you do, in time it will die.”

But that does not mean these oaks – an important species, native to the Willamette Valley – should not be replanted. Quite the opposite. Instead, Hammond suggests embracing the white oak savannah, planting oaks in spaces with natural irrigation and the room they need to thrive.

And for those oaks still standing – Ahrens said that as long as the tree is healthy, with the majority of its crown still intact, it may live for many more years.

“If they have a lush crown, they have a better ability to overcome damage and can mobilize defensive chemicals in their wood,” he explained. “So, the vigorous tree will overcome rot. But these trees that are broken, that don’t have much of a crown, if they don’t have as many leaves the rot can advance. It’s kind of a long-term process and it’s part of what people look at if they decide if the tree can recover. It differs by species.”

Once again, it’s best to look to an arborist for advice and also for help doing the pruning necessary to ensure the tree will grow back in a healthy way.

“[If] ice collected on and broke the upper reaches of most trees, not the lower branches, this creates a difficult pruning fix,” Hammond noted. “Undamaged outer and lower branches can’t remain unpruned if the middle and top are now gone. If they remain the tree becomes donut shaped – not good. So, the whole tree needs to be pruned into balance.”

Which brings up yet another issue, seen all over the north valley – debris. It’s piling up everywhere. Big branches, small branches, whole trees – there’s seemingly no end in sight to the problem which, if dealt with unsustainably can cause huge amounts of carbon to enter the atmosphere. Fortunately, there is an alternative, especially for those with a penchant for gardening. It’s called hügelkultur.

Hügelkultur is an ancient wisdom, a method to compost whole logs and limbs, in long narrow piles, or beds, that can nourish plants in and near them for decades,”
Kris Mitchell, owner of Eastview Garden in Silverton, explained. “It is what happens naturally in the forest, but works faster with human intervention.
“I actually started doing hügelkultur before I knew that’s what it was, over 15 years ago.”

As a farmer, Mitchell understands the value of composting natural materials into her fields and beds.

“Composting is essential for so many reasons,” she said “Even in times when I didn’t have much of a garden, I have always had a kitchen compost, because it is one way to reduce waste in a way that is good for the planet, while returning valuable organic matter, nutrients, and beneficial microbes to the soil…because I build the soil using the organic material produced right here by the plants, animals, and our kitchen, I don’t have to buy additional fertilizers to grow healthy plants.”

Looking at the piles of trees and branches, instead of a problem, Mitchell sees opportunity, hope for the future and a way to build a nourishing foundation for the new trees to come.

“It takes a change of mindset, from thinking of the debris from the ice storm as an ugly mess that we need to be rid of, to seeing it as the valuable resource that it also is,” she acknowledged.

“Use them as a base for a raised bed, adding chips and soil, and grow beautiful flowers and delicious, nourishing vegetables and fruits. Over the course of our lifetimes, the twigs, sticks, limbs, and even whole trees that suddenly came down on our properties in such an alarming and destructive way, can be used by this method to heal and nourish the planet and ourselves.”

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