27 September, 2018
Forestry managers fight fire with flora
|Firefighters try to extinguish a wildfire near Athens in July © AFP
On July 23, a wildfire broke out near the Greek coastal village of Mati, east of Athens. The fire spread rapidly, fanned by 70mph winds and fuelled by the parched vegetation and pine trees. At least 88 people lost their lives.
Residents have described how pine trees "burnt like blowtorches, the pine cones exploding like grenades". The aftermath revealed great expanses of incinerated pines. Without a fuller understanding of how the landscape and its flora contributed to the spread of the fire, any replanting could be creating conditions for a repeat catastrophe.
Mati is a semi-rural suburbia, with the sea to the east and the Marathonas highway to the west. My family have holidayed there with friends who live nearby. In 2013, they introduced me to Norman Gilbertson and Diane Katsiaficas, whose wonderful garden in Kokkino Limanaki is just south of Mati.
Gilbertson and Katsiaficas spent 25 years creating the garden, working with, rather than against, the tough conditions - the average annual rainfall is a meagre 30cm (12in), of which almost none falls between Easter and October. They planted native species along with drought-tolerant edibles, including loquat, citrus and olives. Aleppo pine (Pinus halepensis) and stone pine (Pinus pinea) framed the views out to sea. Gilbertson died in 2015 but Katsificas still lives in the cliffside house. In July, the house and garden were directly in the path of the flames.
Since 2015 there have been large wildfires in Alaska, Indonesia, Canada, Chile, Portugal and Australia. In June a moorland wildfire broke out on Winter Hill near Bolton, England, which burnt for 41 days and reduced seven square miles of moorland to ash. The wildfires across California this year have killed at least 14 people and destroyed more than 1,000 homes. Research by the Sierra Nevada Research Institute supports the impression that wildfires are becoming more common in the US.
The Big Read
Scorched earth: the world battles extreme weather
Dr Andrew Hirons lectures in arboriculture at Myerscough College in Lancashire. "A lot of thought has gone into flood plain management," he says, "but when it comes to wildfires we are domesticating landscapes that we probably shouldn't." He has co-written, with Dr Henrik Sjoman of Gothenburg Botanic Garden, a tree species selection guide. "There's a tension around wanting to live with greater contact with nature and the reality of wildfires. We need better understanding, especially from planners and legislators." This latter point is especially important when planning replanting after fires, he argues. Many of the tree species chosen for their drought resistance are highly flammable and capable of turning a ground fire into a fast-moving crown fire. "Some trees are incentivising a crown fire. It's their strategy," he says. This intention to burn is an example of serotiny, an ecological adaptation by seed-bearing plants where the release of seed is in response to an environmental trigger.
Fire is the most common trigger.
"Trees like Pinus halepensis naturally retain their dead lower branches," says Hirons. It's all part of the serotinous strategy; the dead branches create a ladder for a ground fire to climb. "Resins help pine trees to heal but, along with the oils that occur in the tree, are highly flammable." Eucalyptus, another commonly planted genus in drought-prone areas, also relies on fire for regeneration, using another adaptation - lignotubers. A lignotuber is an at-ground or below-ground swelling, a mass of buds and food that enable the tree to re-sprout after fire. While good for rapid regeneration, the oils in eucalypts are volatile, adding fuel to a wildfire.
Given the threat of wildfires, is adequate investment going into forest management? "In the US, not enough," says Ernesto Alvarado, professor at the School of Environmental and Forest Sciences, University of Washington. "Science that was applied in managing natural ecosystems for most of last century was developed in Europe. The unintended consequences are being experienced now, such as forest health problems and wildfires. Our ‘native' science developed to understand and manage the extensive natural ecosystems in the western US is relatively new."
Tony Kirkham, head of the arboretum at the Royal Botanic Gardens Kew, says: "Good husbandry is key to helping to slow wildfires: crown-lifting trees to remove their lower branches, and then taking those branches away rather than leaving combustible material lying around." Kirkham is an adviser to Quarry Hill Botanical Garden in Sonoma, California. During the October 2017 California firestorm that burnt almost 250,000 acres, leaving 44 people dead and causing more than $9bn of damage, the wildfires came up to the gates of the garden. "What stopped the fires was the good husbandry of the garden and the fact that it is irrigated. Prolonged drought means there is little moisture in the soil or the plants, increasing the risk of combustion."
Hirons and Kirkham agree that mixing tree species is key to reducing the speed of wildfires. And "not just for fire but for resistance to climate change, disease and pests, including alien pests like the Asian longhorn and citrus longhorn beetles", adds Hirons.
As for future planting, Alvarado, Kirkham and Hirons all warn against replanting combustible pines in fire-prone areas. "They hold on to their cones and produce a lot of retained dead wood," says Kirkham. Trees with thick bark, such as cork oak (Quercus suber) and coast redwood (Sequoia sempervirens) have good fire resistance. "Any trees that maintain a level of moisture will work," says Alvarado. "Resistance to local droughts is something most native trees would be adapted to. However, this is true if natural densities and structures are maintained. For the type of droughts predicted under climate change, this may not work because trees will be exposed to droughts that are beyond their resistance."
In Greece, Katsiaficas' garden was badly damaged. In the bay below the garden 33 people died.
Thanks to the efforts of Katsiaficas, along with Evangeli and Sisi who help her, there is "a semblance of a garden left". They had been assiduous in not leaving piles of dead wood around. Pine trees had been pruned and crown-lifted, and hundreds of bags of pine needles swept up and disposed of every year.
"The surrounding plots are tragic scenarios," says Katsiaficas. "The firestorm was ruthless." Yet there are small signs of recovery. "My plum tree was burnt, but it has thrown out new leaves and flowers, as has my lilac," she says. Cactus and succulents have survived, thanks to moisture retained in their thick leaves.
There is concern that the forestry laws that have enshrined the repeated planting of combustible pines will remain unchallenged. But, says Katsiaficas, "in my garden there is hope - in Greek, elpida".
If that hope is to be realised it will need governments to invest in expertise and education, and ensure woodland planting and management strategies offer the best possible chance of reducing the impact of future wildfires.
Source: Financial Times