What happens when the big one hits?

It had rained off and on for weeks, and the winds hit about midnight. Norm Hol had been awake most of the night and began getting calls by 3 am. By 4:30, he was on the road, though the roads were clogged by downed trees and power lines.

“It was chaos,” says Hol, an arborist and consultant and the owner of Arbortech Consulting Ltd., in Richmond, British Columbia. The big storm of last December was horrific for a tree man, with some 30,000 trees blown down and many thousands more damaged in the Vancouver area. There were several lives lost and many structures damaged or destroyed, and much of that was because of trees.

However, as with most disasters, the storm that hit the Pacific Northwest on December 15, 2006, turned out to be a learning experience with some positive benefits. It was one of the worst tree disasters in the history of North America, and it’s been a featured topic in tree circles ever since.

Hol is a former land surveyor and tree service contractor who began doing some part-time tree consultant work in the 1990s and finally set up Arbortech solely as a consulting firm. Based in Richmond, he has two employees now and works primarily with municipalities and land developers. He does a lot of “tree risk assessments,” as hazard analysis is called in his area.

Super-saturated soils and hurricane-force winds caused thousands of trees to topple, leaving sights like this 12-foot root mat throughout the Vancouver area.

He’s had a lifelong fascination with trees, and “the big storm” was an emotional thing for him, as well as a lot of other professional green industry people and environmentalists. He says, however, that the Vancouver area was set up for a tree-related disaster, especially in old natural woodlands where not much tree management had ever been done.

“The trees really are comprised of Douglas fir, western red cedar and western hemlock,” Hol says of the local native species. This fast-growing metropolis is being superimposed on a region originally colonized for the exploitation of its timber, and the 50 to 100-year-old trees in numerous stands interfacing with developments are areas that were once clear-cut and are now thick with second-growth timber. Those stands haven’t been assessed for hazards, and in some areas, there were 160-foot trees interfacing with houses.

“There is limited management in those interfaces, so there’s a lot of risk as a result,” Hol says. Few communities had done any stand thinning or pruning to mitigate it. The storm exploited that vulnerability. There was millions of dollars of damage to street trees and private trees, too, but much of the most severe damage came from where natural woodlands interfaced with development.

This is an environmentally conscious region, he says, and there has been a lot of resistance to tree removal or manipulation in those woodlands. In addition, some communities are reactive in tree issues, only acting after a problem arises. The same applies to many private tree owners.

In mid-November of 2006, the string of storms began with an early snowfall. A series of heavy rainstorms followed, and by December, the ground was so saturated that water was standing in large areas and events on athletic fields were being suspended. The December 15 storm brought its own rain as well, and when the wind hit that night, the conditions were perfect for toppling trees.

“By about 3 in the morning, the city of Vancouver and nearby cities were hit by the highest winds, so many people were asleep,” Hol recalls. The winds reached 87 miles per hour on the coast, but funneling through mountains increased that to 93 miles per hour in some areas.

“Hemlocks are relatively shallow-rooted, so they topple,” Hol says. “The same with western red cedars.” Douglas fir are deep-rooted, but they protect themselves in windstorms by shedding limbs, so there was a lot of damage from fallen limbs and split trunks in addition to toppling.

“Turmoil ensued immediately after the storm,” he says, and winds were still blowing hard. The first thing the city asked him and a forester to do on the spot was to assess whether they should order a mass evacuation because of the number of trees leaning or otherwise threatening homes. Fortunately, winds died down before he finished making his assessment, and evacuation was avoided.

However, it was difficult to get tree service companies in, because many of them were inundated with calls from their other clients. Eventually, two companies with three crews were put to work. Port Moody is a community on a ridge top, and it sustained some of the worst damage. About 50 homes were hit by trees. The crews worked two days just to cut out downed trees and remove or stabilize leaning trees, then spent another four months working on interface trees with less obvious hazards.

It was difficult work because of uncertain and dangerous conditions. Hol would inventory and mark the most hazardous trees, and crews would follow along behind and cut or trim them. Some 800 trees were removed in those interface areas, and numerous trees trimmed, in Port Moody alone.

Norm Hol, owner of Arbortech Consulting, has spent most of 2007 helping the town of Port Moody recover from the storm and prepare for any new ones.

Hol, who worked from dawn to dusk during that period, says it was “a real shame” that so many trees were ruined. However, it actually benefited the interface woodlands by thinning susceptible trees and leaving “wind-firm” trees.

“Maybe it’s better to have trees that are less dense and have better structure,” he says.

The city determined that harsh measures were necessary in the process of managing those woodlands. The first assessment was that those linear interface trees along developments would not be safe unless tunnels were cut through them to allow wind outlets. That meant that many beautiful park and riparian trees had to go.

It was also deemed necessary to do significant pruning to reduce overall foliage and wind resistance. This often took the form of crown thinning and required months of work. Finally, a long-term hazardous tree assessment was initiated to determine where stand thinning would give the woodlands a better chance of surviving a storm of this magnitude in the future.

“That work is still ongoing,” Hol says. Hazard assessment and thinning are important elements in improving the health and wind resistance of remaining trees. The principles will be applied to new developments in Port Moody, so that the strongest trees will be left in those interfaces.

Trunk failures along woodland interfaces resulted from almost 100 mph winds.

In many cities in southwest B.C., Hol says, the storm had one beneficial effect. It woke up planners to the needs of trees. Many communities are doing the same kinds of tree assessments and thinning that Port Moody is doing. Additionally, a lot of new planting is going on, with attention paid to the health and structure of the young trees that will ensure that they grow into wind-resistant trees as they mature.

“A lot of the defects of young trees can be mitigated by pruning,” he points out. The awareness brought on by the big storm is now widespread. Even this summer and fall, municipalities and private property owners were taking care of their trees with the awareness that the annual fall storm season could bring another monster.

In Stanley Park, some 10,000 trees were lost, and the resulting public outcry and debate over different management methods impacts the Vancouver area to this day. The storm has raised tree management and assessment awareness into a major public issue.

That has happened to Norm Hol personally, too. He has changed his tree management views because of what transpired last December. At first, he says, he was obsessed with public safety and being overly cautious. He marked any tree that seemed susceptible as a hazard to be removed. However, because of the number of trees involved and the inability to invariably predict which trees would fall or drop limbs, he has adopted a more tolerant approach. After all, many perfectly healthy trees simply succumbed to extraordinary weather conditions.

Much of the damage to trees occurred where woodlands of hemlock, fir and red cedar interfaced with housing developments in a December 2006 storm. Some 800 trees had to be removed from one small community alone, and an estimated 30,000 trees went down in southwest British Columbia.

“We have to accept that in our region, we live next to large trees,” Hol says. He now advocates that communities be aware of risk and be proactive to avoid as much danger as possible, but not obsess over it. If another storm like this one comes up, it will take down healthy trees, as well as vulnerable ones.

That seems to be the attitude up and down the coast. Communities are eagerly planting new trees to replace many of the ones that fell. They plant them because they value the many benefits that trees provide, but they are also committing more resources and budget to their care and shaping.

Hol learned that much of the damage that will be done in such a storm will be unpredictable. In fact, it was well known that trees along the windward face of such high winds would blow down, but this time there were a lot of trees on the leeward side of stands that blew down. He attributes this to turbulence that not only puts lateral pressure on trees, but also can provide lift that will help uproot a leeward tree.

“A lot of these failures are soil failures rather than tree failures,” he adds. Some massive tree root mats came up as trees toppled, and that particularly happened where soils were shallow or had an impervious soil layer beneath that didn’t allow roots or water to penetrate well. There will be a lot of tree research on subjects such as this because of the big storm, he predicts.

Hol’s business has also benefited from this boom in awareness. He has always gotten tree calls, but he says that has increased by 200 percent since the storm and continues months later. His advice to those worried about future events is the same: Have your trees assessed for hazard and risk, but don’t panic just because you have a tall hemlock next to your house.

Don Dale is a freelance writer and a frequent contributor. He resides in Altadena, Calif.