Understanding what happened to trees in last month’s ice storm

Last month, trees throughout Western Oregon fell as strong winds and snow battered the region. In Portland alone, there are more than a million trees in its parks and nearly 3 million trees on private property. January’s storm affected branches, dead and dying trees, but also healthy trees. What can the city learn about its urban forest following the storm? How should we think about the conifers around us moving forward? We check in on trees with Brian French, arborist and owner of Arboriculture International.

This transcript was created by a computer and edited by a volunteer.

Dave Miller: This is Think Out Loud on OPB. I’m Dave Miller. Last month, trees throughout Western Oregon toppled with snow and ice and battering wind. They fell on homes and cars and roads. A reminder for anybody who needed a reminder that these seemingly stable giants are living breathing vulnerable things. Brian French is a certified arborist and the owner of Arboriculture International. He joins us to talk about the storm, the urban canopy and how we should think about our relationship to our trees. Welcome to Think Out Loud.

Brian French: Thanks, Dave.

Miller: What was the ice storm like for you as an arborist?

French: Well, we have frequent storms coming through the Portland area, but this one in particular, for me personally, it kind of threw me off guard. I wasn’t prepared for it. I knew we were going to have some winds but we started getting calls at about 8:30 in the morning that trees were falling over, and I immediately packed my equipment up and headed into Southwest Portland to see what was going on. And, it was a frightful sight, actually.

Miller: Had you ever seen anything like that in your professional life?

French: Not in my professional life. So, I’ve been an arborist for about 24 years, and we’ve had storms, like very, very notable storms in the past - Columbus Day storm, the storm of 1995, wind storms that particularly hit the Southwest Portland area. But those were before my time.

Miller: One before you were born and the other before you were working.

French: That’s right. I was 16, filling sandbags in Monmouth at that time. But yeah, when we got to Southwest Portland, we were there during the storm both Saturday and Sunday, cutting trees and opening up roadways for people to get to hotels and get out of the neighborhood.

Miller: Were most of the people who were calling you new folks who just looked online and saw that you’re an arborist and desperately needed your help, or existing customers who were in some kind of emergency need?

French: Both. There were a lot of trees down. So we had resources. Portland in general, the community, had resources coming in from all over the country to help with the storm. But I did have some clients who I had already had a working relationship with, but we had a lot of new calls as well.

Miller: If you’d gone around and looked at 100 random trees before the storm - this is a weird hypothetical, but there’s a point to it - and I told you that 50 of the trees were going to come down, do you think that you would have been able to tell, in advance, the ones that would fall and the ones that would remain?

French: On a normal day, I would say yes. In this situation, no. In fact, some feedback that we had from many folks is that arborists had told them that the tree had been assessed before and came out looking OK. And those same trees are trees that had fallen in the storm, so there’s a lot of confusion about that. When we’re offering tree risk assessments, we’re looking at characteristics with a systematic approach that would lead us to recommendations for pruning or care or removal of trees in some cases for normal seasonal storms and a normal year. This is more kind of like a generational storm. And this storm also appeared to the arborist, and I’m talking about from an arborists view, [that it] had almost discriminated which types of trees it was going to take down. In this case healthy conifers.

Miller: So healthy conifers were more likely to come down here than unhealthy hardwoods?

French: Right. So the storm in 2021, where we had an ice storm, which was vast throughout the Portland region and throughout the Willamette Valley, most of the trees that were affected by that storm or Oregon white oak and what we refer to as angiosperms. In this case, gymnosperms, conifers, with healthy, vigorous crowns were actually the trees that [fell]. We saw more of those types of trees failing in this particular storm.

Miller: Do you have an idea for why that was?

French: This storm brought heavy wind winds from 50 MPH and gusts exceeding 70 MPH. I looked this up, I couldn’t actually find a report to offer right now about how that all worked out. I’m sure we’ll have that soon. Areas impacted mostly were in the Southwest, so the Bridlemile Neighborhood, Wilcox HOA, Capitol Hill, Mountain Park area and then up along Skyline. Mount Tabor also was an area that got hit pretty hard by this particular as well.

Miller: Tigard was pummeled.

French: As well, yes.

Miller: So what do you think people who have sizable trees on their properties should do with what you’ve just put forward? In a sense, there was very little that might have prepared folks. Even if they had gotten the services of an arborist, it’s possible an arborist would have said, yeah, this tree is most likely going to be fine in most scenarios. But then we’ve just had this scenario where they weren’t fine. You called it a generational storm and the time period you were mentioning earlier for those other really big storms, it’s about 30 years.

French: 30 years, yeah.

Miller: Does climate change change this in your mind? Do you fear that it’ll upend that period?

French: No. I don’t think I’d really want to talk about my personal fears here, but we do have a frequency of storms. I think that folks who live here in the Pacific Northwest are used to having winter storms. And I think that these 30-year storms, what have you, there’s storms in between that reach some of these winds as well, but maybe the impacts weren’t so severe. That’s part of living in the Pacific Northwest. And that’s something that we need to cope with as a community. And when we’re looking at managing our urban forests, we’re communicating and caring for our trees that way.

Miller: What are some of the most common mistakes that you think people make in terms of the way they approach, manage their own trees? Trees on their properties?

French: Some mistakes would be raising the crown of trees. A lot of folks look at the lower branches of trees when they’re wanting their trees pruned. And this is a really great example of where we wouldn’t want to do that. We are wanting to offer a crown reduction often to reduce the likelihood of whole tree failure.

I think one of the things that maybe isn’t a mistake, but if there was something I could communicate to the community, it would be trees that have codominant stems and included bark–and you can look that up online, included bark. That’s kind of our textbook failure that we see most often in any storm situation where we’re getting calls is due to codominant stems, these leaders in trees that are connected by a weak attachment. And so, if we could just have a better understanding of that and clients or the community calling arborists and identifying and working on those, we would be able to reduce a lot of these tree failures that occur.

Miller: What does that look like, what you’ve just described?

French: It looks like a seam that develops between two stems. And we call this, the aspect ratio is the diameter of both of those stems being nearly equal and the crown above being nearly equal. Over time, the likelihood of those parts can increase the likelihood of failure. And so what we want to do is go in and prune. Sometimes we’ll add supporting cables or bracing systems to reduce the likelihood of those parts failing, but it’s a pretty easy thing for an arborist to address. And so that’s one of the things I’d like to point out is like if we’re going to talk about what we could be doing, that would be like a really easy one. Whereas these 30-year storms are kind of shocking, this is not where I want to be having like our average day conversation at this very elevated point about how to care for trees. If we were pruning our trees and caring for our trees for 70-mile-per-hour violent wind to hurricane wind scenarios, we’d be removing a lot more trees than we would need to and we would have other human health risks and other risks associated with that. And then the only answer to that would be to plant more trees.

Miller: How fearful are you of that some version of that is going to happen, not massive cutting of trees in response to the storm last month, but the lesson that people would take from last month’s storm is, you know what, maybe trees are a problem, maybe tall trees are a problem. Have you heard that from folks?

French: Oh, yes. And that is, I think in general, going on from what we’re hearing from the community of arborists. We’re definitely chatting about our fears of folks removing trees unnecessarily and the impacts that those can have on both the property itself and the other trees on the property, but also as a greater community.

Miller: One thing that I heard right around those storms is that Doug fir, a kind of iconic species here, in the wild, they’re used to growing in communities and they’re buffered from heavy winds because they’re all together which is not the same for a relatively narrow rooted tree, if it’s just a single tree in someone’s yard. Is that true?

French: That’s a really big question. I’ll try to narrow that down for you. We can just talk about any tree rather than focusing on Douglas firs, but trees that are planted in large groups kind of depend on each other the way that they develop. And if we remove some of those trees, the susceptibility of the trees that are still standing is elevated to wind throw. Whereas trees that are open grown with big low branches and a robust trunk and a lot of times a squat, kind of shorter tree, those are the trees that are going to withstand these types of weather systems a lot better. So it has a little bit more to do about the way that they adapt as they’re growing than about the specific species itself.

Miller: I couldn’t have you on the show without asking you about climbing enormous trees because that has been a part of your life as well. What’s it like to be hundreds of feet up in just a massive majestic, hundreds year old tree?

French: Well, I can tell you what it feels like when we come out of a tree like that. We feel like we just stepped off of a ship. So those trees are moving quite a bit all day long up there at 300 feet. Oftentimes, it’s moving back and forth and just the slightest breeze, but there’s almost like a deep murmur or the sound that you can feel as this tree that’s swinging back and forth like a mast on a ship. And yeah, it’s incredible. We would describe it as a place you would think is wet and that’s actually often arid and open, and it looks completely different the way that it looks up there than it does from the ground looking up.

Miller: Well, next time you’re on, we can talk more about this because now I just want to hear more, but the week is done. Brian French, thanks so much for coming in.

French: Hey, you’re very welcome. Thank you.

Miller: Brian French is a certified arborist and the owner of Arboriculture International.

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