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Tree-clearing to reduce fire risks may be completely unnecessary

Research project finds “no scientific evidence” in favour 

A research project in Coimbra has concluded that there is no significant difference in fire behaviour between managed and unmanaged areas next to infrastructure.

In other words, the agony landowners have been put through in recent years in which they were forced to cut back much-loved trees may have been completely unnecessary.

According to Lusa, the research revealed “a lack of scientific support for the current fuel management policy.

“We were unable to prove, in statistical terms, that there is a statistically significant difference between managed and unmanaged areas (next to infrastructure), Joaquim Sande Silva, who co-ordinated the InduForestFire research project with João Paulo Rodrigues, told the State news agency.

For the researcher and lecturer at the Coimbra School of Agriculture, the revision of legislation on fuel management strips that came out in 2018, after the major fires that occurred the previous year, “was not produced on any scientific basis, nor were experts in the field consulted to produce this legislation”.

InduForestFire, which is centred on supporting policy decisions to mitigate urban-forest interface fires, is led by Itecons – the Institute for Research and Technological Development for Construction, Energy, Environment and Sustainability at the University of Coimbra (responsible for the structural component) and the Higher Agricultural School of the Polytechnic of Coimbra (forestry component).

The results and technical recommendations of this scientific project will be presented on Monday at the Coimbra School of Agriculture between 09:00 and 17:30,  writes Lusa.

In the forestry component, the team looked at fuel management and forest composition around infrastructures “against the backdrop of legislation currently in force and in the process of being reviewed and amended”.

According to the researcher, the legislation currently in force has forced “highly debatable work”, with trees of high heritage value being “cut down” without any scientific support that could demonstrate that these same trees would be a threat to the safety of people and infrastructure.

“We wanted to compare fire behaviour within managed strips and in an adjacent unmanaged zone. We did this in ten different locations in the Central region and, in statistical terms, we found no difference in fire behaviour between the managed and unmanaged zones,” he said.

The researcher emphasised that in the managed areas, the vegetation is reduced, but as they are more open areas, the wind speed tends to increase in these places, and the material is “drier, and the temperature on the ground is higher”.

For Joaquim Sande Silva, if you reduce the amount of fuel, you end up increasing “the conditions for propagation”.

In the lecturer’s view, there was some haste in the legislation that came out in 2018 in reaction to the large fires that had occurred in 2017 (killing over 100 people and injuring many more).

In addition to analysing fire behaviour in fuel management strips, the project team also analysed fire behaviour in a hardwood area.

Using fire simulations but with input data that was “very close to reality” – with fuel characteristics and micro-meteorological data collected in the field – it was possible to conclude “that it is more advantageous to have a hardwood cover than just an open field“, he said (in other words, there is an advantage to keeping trees…).

In addition, the researcher stressed that Portugal currently has “a big problem with invasive species”, such as acacias, which tend to propagate “in these areas of fuel management strips.

“The maintenance of these strips is very unsustainable, from a financial point of view, and, on the other hand, with hardwoods, there is a maintenance of shade that ensures that very little or nothing grows underneath,” he explained, giving the example of Arganil’s Margaraça Forest, where the fire of October 2017 (one of the season’s killer blazes) passed, but where the behaviour was very different – a low fire that ended up being extinguished as soon as it reached the wettest areas of the forest.

These findings will be very hard to take (they will exasperate people who were forced to cut down mature trees under threat of stiff fines if they didn’t), which is perhaps why this research has been ‘released’ on a Sunday.

Source material: Lusa