Fire-resilient landscape

What is a fire-resilient landscape?

A fire-resilient landscape is shaped so that a fire finds no unbroken carpet of dry fuel. Groves, pastures, fields, tended shrubland, paths and water alternate. A fire that enters such a landscape slows down, stays closer to the ground and can be stopped more easily. Resilience also covers what comes after: plants resprout or germinate, the soil stays in place and the land recovers.

The goal is not a landscape without fire. In a climate with a long, hot, dry summer that would be an illusion. The Portuguese fire scientist Paulo Fernandes describes the alternative as fire-smart management: instead of relying only on fighting fires, it works on the vegetation itself, on how much fuel there is, how it is arranged and which plants grow where.

Fire belongs to the Mediterranean

Fire is older than any farm. Juli Pausas and Jon Keeley show in their review of fire in the history of life that wildfire appeared together with the first land plants and shaped plant adaptations long before there were people; later, humans used it to reshape whole landscapes. The five Mediterranean-climate regions of the world, the Mediterranean Basin, California, central Chile, the Cape region and south-western Australia, share wet winters and dry summers, as Philip Rundel and colleagues describe in their review of Mediterranean biomes. The wet season grows plant mass, the summer dries it out. Fire is part of this rhythm.

That is why many Mediterranean plants carry answers to it. A review by Pausas and colleagues asked whether wildfires are a disaster for the Mediterranean Basin. Their answer was differentiated: many shrublands and oak forests recover well, pine woodlands are more vulnerable, and the worst damage occurs where people had already weakened the land, for instance in pine plantations on former fields.

Why fires are getting bigger

What has changed is not that fire exists, but its scale. A review of landscape and wildfire in southern Europe led by Francisco Moreira concludes that socio-economic change has pushed land cover towards higher fire hazard and that large fires have become more frequent. Fields and pastures were abandoned, shrubs and young forest grew over them, and fuel that used to be broken up by crops, grazing and wood cutting became continuous. Repeated fires in turn favour uniform shrubland, which burns again.

The climate adds to this. A study by Marco Turco and colleagues in Nature Communications projects that summer burned area in Mediterranean Europe increases by roughly 40 to 100 percent between 1.5 and 3 degrees of global warming, and more strongly the warmer it gets. The authors expect significant benefits if warming stays well below 2 degrees.

Fernandes notes that fire policy has long favoured suppression and neglected land management. Both reviews also name a limit: in extreme fire weather even a well-managed landscape can burn.

The mosaic principle

The central idea is the mosaic. A fire runs along continuous fuel. Where olive groves, grazed pasture, fields, vineyards, open woodland and tended macchia alternate, the fuel is interrupted again and again. Fernandes lists three ways of working on vegetation: isolating fuel with breaks, changing its structure, for example by thinning and pruning, and converting it to less flammable types.

The reviews of land abandonment describe the reverse: where crops, grazing and wood cutting stopped, the mosaic closed. A mosaic does not mean clearing everything. Macchia that protects steep slopes from erosion keeps its place; it is broken up by paths, pasture and groves of cork oak or holm oak rather than removed.

Grazing and agroforestry as fire protection

Animals are among the cheapest tools for keeping fuel low. In Andalusia the regional government has paid shepherds since 2005 to keep firebreaks in public forests grazed. A study by Elsa Varela and colleagues in 2018 counted about 220 shepherds maintaining almost 6,000 hectares of fuel breaks and judged the scheme more efficient than clearing by machine. In Sardinia, a modelling study from the University of Sassari found that forest grazing markedly reduced the simulated extent of fire, by different amounts in wet, average and dry years. More on this under managed grazing.

Agroforestry points the same way. A European study by Damianidis and colleagues compared fires from 2008 to 2017 with land use: agroforestry land covered 12 percent of the area but was linked to only 6 percent of fires, while shrubland covered 16 percent and accounted for 41 percent. The authors name grazing as the main reason, because animals remove part of the dry vegetation near the ground. These are correlations, not proof of cause, but grazed woodland, the silvopastoral system, combines shade, fodder and a broken fuel layer. David Holmgren also counts silvopasture and grazing among the elements of bushfire-resilient land.

Around buildings: zones and distances

Near houses the general advice of fire services and university extension services is consistent. The examples here come from California and Oregon and are recommendations, not rules for any particular country; local fire services know the regional requirements.

The UC Marin Master Gardeners of the University of California describe three zones. In the first 1.5 metres around a house, the goal is to stop embers from igniting it: no combustible mulch, preferably no plants, gravel, stone or paving instead. Oregon State University Extension adds that a plant kept there should be healthy, watered, spaced from other vegetation and surrounded by gravel, and not stand under windows or eaves. From about 1.5 to 9 metres the area is kept "lean and clean": low, well-watered plants close to the house, larger shrubs and trees further out, mulched areas broken up by gravel or stone paths, firewood stored beyond this zone. From about 9 to 30 metres the aim is to break up continuous, dense vegetation.

Spacing matters more than species. The UC Marin guidance states that all plants burn. Plants that collect dead twigs, needles and dry leaves are more dangerous, while healthy, well-kept ones resist longer. Lower branches of tall trees are removed to about 2 to 3 metres or a third of the tree's height, so that a ground fire cannot climb into the crown. Rows and continuous hedges act as fuses. On slopes spacing is wider, because fire runs uphill fastest. In permaculture these ideas belong to the zones and the fire sector.

Water, mulch and cuttings in the dry season

Moisture slows fire. Irrigated gardens, green plantings near the house and moist hollows burn less readily than dry grass. Holmgren speaks of rehydrating landscapes: water that soaks in and is held in the soil keeps vegetation green longer into the summer.

Mulch protects the soil, but dry organic material is fuel. In the Mediterranean garden year, cutting therefore happens in the wet season, as with chop and drop: cuttings laid flat on moist soil decay, while loose heaps of dry branches in summer feed a fire. No dry mulch or cuttings are piled against buildings, along paths or in firebreaks; there gravel, stone or green, living plants cover the soil better.

Fire in Sardinia

Sardinia knows fire well. The official landscape survey of the Ogliastra records that fire, overgrazing and unsuitable tillage removed much of the district's original cork oak and holm oak cover. In late July 2021 a fire in the Montiferru area in the west of the island burned about 13,000 hectares of fields, trees and pasture. The European Space Agency described it, on the basis of Copernicus Sentinel-2 images, as Sardinia's most destructive fire in thirty years.

After the fire: resprouters and seeders

Mediterranean plants follow two main strategies after fire. Resprouters survive and grow again from protected buds. The cork oak is the best-known example: its bark insulates the trunk. In a study by Filipe Catry and colleagues of 22 wildfires with 4,585 cork oaks in Portugal, Spain and France, vulnerability fell as bark grew thicker, up to a cork thickness of about 3 to 4 centimetres, and trees whose cork had been harvested were more likely to lose their crown. About 16 percent of the trees died; 56 percent resprouted from the crown alone. The holm oak and many shrubs of the macchia sprout again from the root crown, as the review by Pausas and colleagues describes.

Seeders take the other route. Rockroses (Cistus) die in the fire, but their seeds wait in the soil. In a laboratory study by Aguayo-Villalba and colleagues, untreated seeds of Cistus ladanifer and Cistus salviifolius barely germinated, while a short pulse of heat of about 100 to 125 degrees Celsius raised germination sharply. After a fire, such pioneer plants cover the open ground quickly and start a new ecological succession.

Limits

A fire-resilient landscape costs work every year: grazing, cutting, pruning, keeping paths open. It works at the scale of a whole landscape; a single garden surrounded by dry shrubland remains exposed. And clearing steep slopes down to bare soil reduces fuel but opens the way to erosion.

How Terra Humana understands fire-resilient landscapes

For Terra Humana fire is part of the Mediterranean, not an enemy that can be defeated. Renaturation in this climate means shaping landscapes that live with fire: varied, grazed and used, with water held in the soil and with plants that can come back. The research on resprouters and seeders shows that much of what such landscapes need is already present in the macchia and the oaks. What a particular place needs has to be read from the place itself, from its slopes, winds and history of fire.