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8 hours ago
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The city of Asheville and its surrounding areas have been left vulnerable to floods, fires and extreme heat after Hurricane Helene uprooted thousands of trees that provided shade and protection from storms.
Helene was catastrophic for the region’s trees – in part due to the heavy precursor rainstorm that pounded southern Appalachia for two days straight, drenching the soil before Helene hit, bringing yet more heavy rain and 60-100mph winds.
The category 4 storm caused severe damage to more than 400,000 acres of forest in rural areas of western North Carolina alone, stripping entire mountainsides bare, according to the latest assessment by the US Forest Service. Almost half the forest in Mitchell county was severely damaged, as was about 30% in Ashe and Watauga and 17% in Buncombe county.
The extent of the tree damage is “extraordinary and humbling”, according to Steve Norman, a research ecologist who conducted the assessment using remote sensing satellites at the Forest Service’s Southern Research Centre.
The damage count does not, however, include urban areas like Asheville, a city in Buncombe county which suffered unprecedented large-scale tree failures leaving some streets and neighborhoods completely bare.
Asheville is among the fastest-growing small US cities, with many drawn to the city’s art scene and claims that it was a climate haven.
Yet tree cover was already declining even before Helene – the city lost 6.8% of its tree canopy between 2008 and 2018, according to one study, while the population grew by 10%.
Then Helene, the most powerful storm to hit southern Appalachia in decades, submerged Asheville’s River Arts District along the French Broad River, and Marshall, another artsy town, both in flood water. The river is now a silty eroded mess, with little vegetation to protect the land from future storms, flanked by piles of tree debris.
Yet not all trees fared the same, according to new analysis shared exclusively with the Guardian. Hard woods such as red oaks, hickories and eastern white pines accounted for 70% of the trees upended by hurricane-force winds in Asheville, while softwoods including tulip trees and maples were far less prone to failure.
Trees provide essential ecosystem services in urban areas including cooling, carbon sequestration, storm water management, wildlife habitat, air pollution capture and mental, physical and spiritual wellbeing. The new research led by April Wilson, a certified master arborist, is an attempt to understand which species may suffer worst in supercharged storms fueled by human-made global heating.
In the immediate weeks after Helene, Wilson conducted a survey of 300 fallen trees in 11 suburban and urban neighborhoods in the Asheville area. Eighty-three per cent had no obvious defect: these were healthy-looking trees with no root rot, hollow trunks or other major structural problems.
In January, Wilson surveyed 800 randomly selected standing trees, a control group of survivors from the same neighborhoods. The analysis, conducted with Jenna Rindy, a local environmental scientist with research experience in forest biology, found that size and species had significant associations with failure.
Medium to large trees – those between 16 and 36 inches in diameter - were 83% more likely to fail than smaller ones. Previous studies in other locations have shown that larger trees are more prone to failure in extreme storms than those with smaller diameters. In Asheville, smaller and extra-large trees fared best.
Red oaks and eastern white pines accounted for 43% of the failures. It’s unclear why but oaks hold on to their leaves more than other trees, which increases drag – or heaviness of the canopy. Other possible explanations include root size and the impact of previous climate crisis-fueled disasters, particularly drought.
Medium- to large-sized northern red oaks were the most prone to failure, the analysis found.
“While we want to avoid making sweeping tree management decisions based on this singular storm, we can conclude large oak trees should be further assessed in the urban landscape – even those without detectable defects. Species with a lower likelihood of failure, including many minimal-risk native species to our area, should be considered for planting near high-value targets,” said Wilson.
While catastrophic floods have hit the Asheville region in the past, the large-scale tree failures caused by Helene appear to be unprecedented.
“Climate change may have made some trees more vulnerable … and now so much forest around us was destroyed or damaged. That’s a lot of lost CO2 and in the city, runoff, erosion and heat issues are real,” Wilson said. The research is being submitted to a peer-reviewed journal.
In one northern suburb, homeowner Sari Bellmer lost multiple trees including two large hickories and a 70-year-old red oak, which fell on top of the house, leaving the garden bare, the property exposed.
Across the street, power lines and an entire row of cypress trees fell like dominoes. Four months after Helene, a small urban forest behind Bellmer’s house was being bulldozed to make way for new housing.
“We live on a ridge facing a road and felt protected by the trees, but are now totally exposed to the wind and heat,” said Bellmer, whose business in Marshall also flooded. “We need fast-growth trees to protect the soil and house, but I also want diversity and shade to compensate for the trees lost to Helene – and the new development.”
At least 220 people were killed by Hurricane Helene, including 104 deaths in North Carolina – mostly caused by floods and falling trees. Many trees were severely damaged or hanging dangerously and needed to be removed. But arborists interviewed by the Guardian also reported an uptick in traumatized residents removing healthy trees that could have been saved – compounding vulnerability to future rain and wind, and removing precious carbon from the soil.
In all, more than 800,000 acres of forestland were damaged, and in some cases flattened entirely, throughout 17 counties in western North Carolina. This includes about 20% of the state’s national forest, leaving lots of kindling-like vegetation on the ground that could fuel fires – and fewer trees to slow winds down, according to Norman, who was speaking at a public event in January before Elon Musk fired 10% – 3,400 – of US Forest Service staff.
“The fire risk is a huge concern,” warned Norman,
Last week the North Carolina forest service listed 176 fires spanning more than 3,300 acres – the largest in Polk county in the western part of the state.
“Asheville is absolutely less climate resilient than it was before Helene but this was a wake-up call. Maybe now we will update floodplain maps, implement the 2018 climate resilience assessment and construct more green infrastructure to absorb stormwater on the land left exposed by Helene – and the development boom that’s been happening,” said Alison Ormsby, forest specialist with the non-profit Adventure Scientists and volunteer co-chair of the city’s tree protection taskforce.
“We thought this was a climate refuge so this was a huge irony that shattered our sense of security,” Ormsby said.
In 2018, Asheville had 44.5% city-wide tree canopy, comparable with other similar cities but this varied hugely with some neighborhoods experiencing higher temperatures due to few trees and the urban heat island effect. Since then urban development has continued apace, yet the city has not updated its tree protection ordinance in 15 years.
Amid growing concern about tree loss and unsustainable development, the city last year hired Asheville’s first urban forester – and commissioned a new canopy study and public tree inventory. These important climate resilience initiatives were temporarily suspended when Helene struck.
There is no tree baseline for Asheville, making it difficult to know how many had been cut down before the storm.
“We used to be a green city but we had already lost so many trees to development, that Asheville was not as resilient as it could have been when Helene hit. The hurricane absolutely compounded the issue, and we are 100% more vulnerable to climate disasters – to floods, heat and all the other things that trees do for us,” said Chardin Detrich, a master arborist and member of the Urban Forestry Commission which advises the city on tree planting and preservation.
“We need to increase diversity of tree cover, plant better, stop cutting down trees …rethink development completely in order to increase resilience of this area moving forward. So far there’s little evidence of the city changing course.”
“Asheville has a long track record of recognizing the role sustainability plays in maintaining and improving our community,” said a city spokesperson, Kim Miller. “Public engagement has clearly demonstrated residents’ deep commitment to sustainable rebuilding. Staff is actively pursuing federal and state funds to integrate mitigation strategies into recovery efforts to ensure a more resilient recovery from the disaster.”
