The Soil Microbiome of the Laurel Forest in Garajonay National Park (La Gomera, Canary Islands): Comparing Unburned and Burned Habitats after a Wildfire

Abstract

The evergreen laurel forest is a relic of ancient subtropical/tropical forests, of which the best remnant in the Canary Islands is in Garajonay National Park, on La Gomera island. The soil microbiome associated with a mature undisturbed (unburned) laurel forest was characterized at two locations at different topographical positions on the mountain: The slope and the ridge crest. Given the unusual circumstance of an intense wildfire that severely affected part of this forest, the burned soils were also studied. The soil in undisturbed areas was relatively uniform. The bacterial community composition was dominated by bacteria from phyla Proteobacteria, Acidobacteria, and Actinobacteria. The wildfire changed the composition of the bacterial communities. The Acidobacteria, Actinobacteria, and Alphaproteobacteria (dominant class in unburned forests) significantly decreased in burned soils along with a parallel high increase in Betaproteobacteria, Bacteroidetes, and Firmicutes. We further showed the dramatic effect of a wildfire on the soil microbiome of the laurel forest, appearing as a loss of species richness and diversity, species dominance, and changes in the composition of the bacterial communities.

Linking Bacterial Rhizosphere Communities of Two Pioneer Species, Brachystegia boehmii and B. spiciformis, to the Ecological Processes of Miombo Woodlands

“…In line with the results reported in other forest ecosystems (e.g., [52,53]), Actinobacteria, Proteobacteria, and Acidobacteria were the most abundant phyla (Figure 1). Bacteria belonging to these phyla usually participate in C, N, and S cycles and are also responsible for the production of secondary metabolites associated with plant resistance to pathogens [54].…”

The Nexus between Fire and Soil Bacterial Diversity in the African Miombo Woodlands of Niassa Special Reserve, Mozambique

“…700–800 to ca. 300 OTUs) [ 68 ]. Thus, soil dynamics depend on a complex nexus of several factors, including anthropogenic and environmental parameters [ 27 , 69 , 70 ] that are probably site-specific.…”

“…These phyla are frequently reported in the soils of other forest ecosystems [ 9 , 68 , 76 , 77 ] comprising ubiquitous bacteria with a multiplicity of ecological functions such as soil fertilization, bioremediation and plant nutrition, growth, and protection [ 1 , 78 , 79 ]. In general, the bacterial variation patterns imposed by HFF followed the same trend in S and R soils, contrasting with O soils.…”

“…This was unexpected, as from a physical and chemical point of view, R and O soils are more similar, although all Miombo soils are generally nutrient-poor, acidic, and have a low cation exchange capacity [ 14 ]. Plausible explanations for this discrepancy may be the severity of the burnings as well as the phytosociological status at the sampling sites [ 15 , 68 ].…”

Wildfires disturb the natural skin microbiota of terrestrial salamanders

“…While our study did not directly measure soil microbiota, our observations correlate with those performed by microbiota surveys of burnt soils. In Villadas et al (2019), Dove et al (2022), and Pulido‐Chavez et al (2023), a swift reduction in diversity is typically observed immediately after a fire followed by a boost in taxonomic diversity that results from the release of pyrogenic nutrients. In our observations, salamander skin microbiota possessed a greater taxonomic diversity of bacterial phyla in burnt areas immediately after a wildfire (those sampled from burnt areas in 2021) compared to those sampled a few years after the last wildfire (those sampled from burnt areas in 2018).…”