The new fires caused by global warming

Due to global climate change, many ecosystems are experiencing a disturbance in their fire regime, with an increase in fire frequency and severity. This can substantially alter plant communities, as well as the structure and functioning of ecosystems. A new study has explored the extent of this disruption.

The study has been led by the Desertification Research Center (CIDE), a joint center of the Higher Council for Scientific Research (CSIC), the University of Valencia (UV) and the Generalitat Valenciana, in Spain.

After examining data from a large number of fires around the planet, the study authors found that the intensification of fire regimes caused by climate change and other human activities significantly reduces abundance, diversity and fitness of plants, as feared, and that this also affects woody plants more, so vegetation areas such as coniferous forests are especially affected.

“This research provides, for the first time, a global, systematic and quantitative vision of the effect of fire intensification,” says Juli G. Pausas, CSIC researcher at CIDE and co-author of the study.

To carry out this work, the authors applied a systematic review and meta-analysis methodology that allows analyzing many data from very diverse sources. Thus, they managed to systematize 2,363 cases collected in 394 studies spread throughout the planet, although with greater representation from the northern hemisphere.

When considering the components of the fire regime such as its frequency, intensity or type, the study shows that the greatest risk for plants comes from the severity of the fires. In other words, the negative effects are stronger with increasing fire severity than with increasing fire frequency.

The problem, as it was proven, does not affect all types of vegetation equally. “Coniferous and mixed forests are more susceptible to fire intensification than open ecosystems such as grasslands and shrublands, something related to the possible change from low-intensity surface fires to high-intensity crown fires,” says Roger Grau. Andrés, researcher at the Center for Ecological Research and Forest Applications (CREAF), in Cerdanyola del Vallès, Barcelona, ​​and first author of the work.

According to Pausas, “Mediterranean-climate shrublands are dominated by crown fire regimes that have historically burned with high intensity, and these ecosystems are remarkably resilient to such conditions. But, in this case, an increase in the frequency of disturbances can also lead to a decrease in diversity.”

Forest fire. (Photo: NPS)

Another example of the threat from changes in the fire regime is offered by the black pine or Pinus nigra, abundant in the Iberian Peninsula. “This tree is prepared to survive low intensity fires thanks to its thick bark, which insulates it from flames, and its few branches in the lower part, which prevent the transmission of fire to the crown. However, in the event of more intense fires or fires that affect the entire tree, these protections are not enough and the plant does not survive,” explains Moreira.

The researchers highlight that this study “provides a scientific basis to help make decisions on ecosystem conservation and fire management policies,” since it manages to identify the general patterns of plant response to the intensification of fire regimes. fires and understand the factors that determine them. By understanding changes in fire regimes, strategies adapted to these new fires can be created.

Thus, “more than a single unified policy, it is about understanding which ecosystems may be most susceptible and establishing priorities for action,” says Pausas. Therefore, unlike more resilient ecosystems, in which “the best conservation strategy may be to do nothing”, coniferous forests would require adequate management. For example, in Pinus nigra forests, which are resilient to low-intensity fires and are able to survive frequent surface fires, prescribed fires can help maintain a low-intensity fire regime that gives trees greater opportunities to avoid suffering from high intensity fires.

The study is titled “Global plant responses to intensified fire regimes.” And it has been published in the academic journal Global Ecology and Biogeography. (Source: Isidoro García / CSIC)