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Controlled burn for increasing biodiversity

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A controlled or prescribed burn is a wildfire set intentionally for purposes of forest
protection management. It may be used for farming, prairie restoration and
wildfire’s prevention. The latest has been considered by EFI - European Forest
Institute - one of the best preventing solution and has been implemented by the
EU civil protection mechanism in the most affected European member states. In
Portugal, the ICNF - Instituto da Conservação da Natureza e das Florestas - is
responsible for managing and planning prescribed burns.
Summer wildfires represent a serious threat for National native forests’ ecological
equilibrium all over Portugal [see EFFIS data - The European Forest Fire
Information System A/N]. In burnt areas few trees are able to grow from the
impoverished soil - except for some pyriscence genera which have adapted to
wildfire such us Pinus, Cupressus and Picea. Thereafter other plants and shrubs
can easily spread in new open areas without finding much competition for both
nutrients and sunlight. For this reason a different type of prescribed burn is often
used in order to diminish the impact of low shrubs, in particular broom Genisteae.
The organisations part of the European Nature 2000 network - such us Montis
and Plantar Uma Árvore - are actively using controlled burns to manage broom
Genisteae’s spread and let new planted trees have more probabilities of survival
by increasing growth’s speed. The best solution would be to manually remove
undesired shrubs and vegetation but this operation has much higher costs in
terms of personnel, time and effort.
These controlled burns - for the purpose of forest conservation - are usually
performed during winter or spring to prevent the soil from being impoverished.
The weather conditions are very important to decrease the energy released by
combustion, with mild or low temperature and with light to moderate winds. What
is achieved is a decrease in thinner fuels (leaves, twigs, bark, dead cover)
without the present vegetation burning deeply and without the seeds and buds of
the plants being particularly affected. In these areas new trees are planted closer
to one another to prevent shrubs and bushes from excessively regrowing and
creating shade.
For broom Genisteae is highly resilient it is necessary to repeat the operations in
few years’ time (usually four years after a previous controlled burn). This practice
has been successfully carried out, together with forest conservation activities and
represent a valid solution to increase the recovery speed of the ecosystems
It is important to understand the differences between controlled burn for wildfire
prevention on one side and the one applied for the purpose described above on
the other, which aims to create a favourable habitat for native trees to grow,
consequently increasing biodiversity as a main ideal outcome.
Additionally these actions enhance lands’ fire resilience and are perfectly in
accordance with the general wildfire prevention objectives set by national and
European institutions, which benefit from the advices of among the best experts
around the globe.