The combined effect of climate change and forest fires can transform forests into bushes
According to a study carried out by the University of Alicante and the University of Utrecht, in collaboration with other Dutch and Spanish research centres
Experimental fire in Mediterranean scrub. Photo: M. Jaime Baeza
Alicante. Thursday, 5 December 2019
A study carried out by researchers from the University of Alicante and the University of Utrecht, in collaboration with other Dutch and Spanish research centres, shows how the increase in aridity expected over the coming decades will make Mediterranean forests more vulnerable to forest fires. This fact, as a consequence of climate change, and the forecast of increasing droughts may lead to the permanent replacement of pine and holm oak forests with scrubland and grassland.
As detailed in this paper, recently published in the journal 'New Phytologist', climate change may particularly severely affect the Mediterranean basin, and holm oaks and hardwoods will be impacted by drier and warmer conditions.
The most common leafy species in the Mediterranean area, the holm oak, is perfectly adapted to withstand fires. The reason is that this tree is slightly flammable, and comes along a wet undergrowth that hinders the spread of fire. It is also very resilient to fire, as it can quickly resprout from the root after a fire, but even this particularly adapted species has its Achilles' heel, as stated by Susana Bautista, a researcher at the University of Alicante Multidisciplinary Institute for Environmental ResearchRamón Margalef. In this sense, the expert insisted that climate change is expected to affect the Mediterranean basin in a particularly severe way and, thus, holm oaks and other hardwoods will be exposed to extreme conditions that will weaken their growth and response to fire.
Reforestation with hardwoods
This weakening of the response to fire may lead to the disappearance of these forests in the future, Susana Bautista confirmed. The results of this research model suggest that reforestation with hardwoods can prevent the spread of forest fires, accelerating the relatively low capacity of these species to colonise new areas. However, even relatively non-flammable species may be at risk in the face of expected changes in climate over the coming decades, as explained by the University of Alicante's expert on land degradation and desertification.
The researchers of this work have used field data from decades to parameterise a model that includes the fire response of the most common species of trees, shrubs and herbaceous plants of the Mediterranean mountains. According to Utrecht University expert Mara Baudena, predicting the future of forest fires and vegetation in a changing environmental context requires specific responses of large groups of vegetation in the models, whether specific to the Mediterranean region or global models such as those used by the IPCC, the Intergovernmental Panel on Climate Change.
In the image, holm oak regrowing after a forest fire. Photo: Fundación CEAM.
“Increased aridity drives post-fire recovery of Mediterranean forests towards open shrublands”. New Phytologist (2019). doi:10.1111/nph.16252
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