THE cypresses They adopt a particularly fascinating and effective strategy in defense against fires, exploiting unique chemical and morphological mechanisms. In fact, they have a much higher resistance than many other Mediterranean species. Try to “Protect yourself” actively from fire through a combination of physical and biochemical characteristics.
But how do they do? In practice, the Cypringe’s serotini cones remain closed for decades and open only under the effect of intense heat. But, unlike plants such as the Pino d’Aleppo, these cones they open by releasing seeds already in placewithout promoting the dispersion of fiery lapilli that feed the front of the fire.
In addition, rapid growth in height and the natural “self -employment” ability raise the hair above the fuel planinterrupting the continuity between foliage and low branches, hindering the propagation of the flames. Finally the needles and the litter underlying they retain humidity longer And the Chiara hair slows down the convective motorcycle of the fire.
Chemical Defense: the release of volatile terpenes
But it is the biochemical component which amazes more. Cypresses summarize and accumulate terpenids – highly flammable volatile organic substances – in wood, in the cortex and in the needles. In stress conditions, such as approaching the heat of a fire or fungal attack, the production of these compounds increases drastically.
A study on resistant clones and susceptible to fungal diseases has shown that, after infections, the bark of resistant cypresses showed an increase up to 7 times greater of the content of terpenoids. Paradoxically, these same compounds, despite being flammable, play a protective role: local heating induces the evaporation of birds, reducing the amount of flammable residual material in the vegetable tissue, thus decreasing the probability that secondary needles take fire directly.
Chemical communication between trees
Even more extraordinary is the “alarm” effect: the volatile molecules released are transported by the wind and perceived by neighboring cypresses, activating in them a preventive response. In practice, the plant “feels” the danger and promptly triggers the production of its protective compounds, creating a sort of olfactory defensive network.
This integrated system – protective morphology, release of terpenes and communication between individuals – makes cypresses excellent candidates for natural fire barriers in risk areas. They are species that light up more slowly (up to seven times more slow than pine trees and other Mediterranean species), ideal for mitigating medium intensity fires. Experimental tests conducted in Italy and Spain therefore suggest their strategic use to slow down and circumscribe fire.
